js/xpconnect/src/XPCJSRuntime.cpp
author Andrew McCreight <continuation@gmail.com>
Tue, 29 Jul 2014 15:38:14 -0700
changeset 208231 84bf8e0aaecb
parent 206099 7792ac87eb27
permissions -rw-r--r--
Bug 1037510 - Part 1: Add nursery size as a parameter of CycleCollectedJSRuntime. r=khuey, a=sledru

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set ts=8 sts=4 et sw=4 tw=99: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Per JSRuntime object */

#include "mozilla/MemoryReporting.h"

#include "xpcprivate.h"
#include "xpcpublic.h"
#include "XPCWrapper.h"
#include "XPCJSMemoryReporter.h"
#include "WrapperFactory.h"
#include "dom_quickstubs.h"
#include "mozJSComponentLoader.h"

#include "nsIMemoryInfoDumper.h"
#include "nsIMemoryReporter.h"
#include "nsIObserverService.h"
#include "nsIDebug2.h"
#include "amIAddonManager.h"
#include "nsPIDOMWindow.h"
#include "nsPrintfCString.h"
#include "mozilla/Preferences.h"
#include "mozilla/Telemetry.h"
#include "mozilla/Services.h"

#include "nsContentUtils.h"
#include "nsCxPusher.h"
#include "nsCCUncollectableMarker.h"
#include "nsCycleCollectionNoteRootCallback.h"
#include "nsScriptLoader.h"
#include "jsfriendapi.h"
#include "jsprf.h"
#include "js/MemoryMetrics.h"
#include "js/OldDebugAPI.h"
#include "mozilla/dom/GeneratedAtomList.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/WindowBinding.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "AccessCheck.h"
#include "nsGlobalWindow.h"
#include "nsAboutProtocolUtils.h"

#include "GeckoProfiler.h"
#include "nsIXULRuntime.h"
#include "nsJSPrincipals.h"

#ifdef MOZ_CRASHREPORTER
#include "nsExceptionHandler.h"
#endif

using namespace mozilla;
using namespace xpc;
using namespace JS;
using mozilla::dom::PerThreadAtomCache;

/***************************************************************************/

const char* const XPCJSRuntime::mStrings[] = {
    "constructor",          // IDX_CONSTRUCTOR
    "toString",             // IDX_TO_STRING
    "toSource",             // IDX_TO_SOURCE
    "lastResult",           // IDX_LAST_RESULT
    "returnCode",           // IDX_RETURN_CODE
    "value",                // IDX_VALUE
    "QueryInterface",       // IDX_QUERY_INTERFACE
    "Components",           // IDX_COMPONENTS
    "wrappedJSObject",      // IDX_WRAPPED_JSOBJECT
    "Object",               // IDX_OBJECT
    "Function",             // IDX_FUNCTION
    "prototype",            // IDX_PROTOTYPE
    "createInstance",       // IDX_CREATE_INSTANCE
    "item",                 // IDX_ITEM
    "__proto__",            // IDX_PROTO
    "__iterator__",         // IDX_ITERATOR
    "__exposedProps__",     // IDX_EXPOSEDPROPS
    "eval",                 // IDX_EVAL
    "controllers",           // IDX_CONTROLLERS
    "realFrameElement",     // IDX_REALFRAMEELEMENT
};

/***************************************************************************/

static mozilla::Atomic<bool> sDiscardSystemSource(false);

bool
xpc::ShouldDiscardSystemSource() { return sDiscardSystemSource; }

static void * const UNMARK_ONLY = nullptr;
static void * const UNMARK_AND_SWEEP = (void *)1;

static PLDHashOperator
NativeInterfaceSweeper(PLDHashTable *table, PLDHashEntryHdr *hdr,
                       uint32_t number, void *arg)
{
    XPCNativeInterface* iface = ((IID2NativeInterfaceMap::Entry*)hdr)->value;
    if (iface->IsMarked()) {
        iface->Unmark();
        return PL_DHASH_NEXT;
    }

    if (arg == UNMARK_ONLY)
        return PL_DHASH_NEXT;

    XPCNativeInterface::DestroyInstance(iface);
    return PL_DHASH_REMOVE;
}

// *Some* NativeSets are referenced from mClassInfo2NativeSetMap.
// *All* NativeSets are referenced from mNativeSetMap.
// So, in mClassInfo2NativeSetMap we just clear references to the unmarked.
// In mNativeSetMap we clear the references to the unmarked *and* delete them.

static PLDHashOperator
NativeUnMarkedSetRemover(PLDHashTable *table, PLDHashEntryHdr *hdr,
                         uint32_t number, void *arg)
{
    XPCNativeSet* set = ((ClassInfo2NativeSetMap::Entry*)hdr)->value;
    if (set->IsMarked())
        return PL_DHASH_NEXT;
    return PL_DHASH_REMOVE;
}

static PLDHashOperator
NativeSetSweeper(PLDHashTable *table, PLDHashEntryHdr *hdr,
                 uint32_t number, void *arg)
{
    XPCNativeSet* set = ((NativeSetMap::Entry*)hdr)->key_value;
    if (set->IsMarked()) {
        set->Unmark();
        return PL_DHASH_NEXT;
    }

    if (arg == UNMARK_ONLY)
        return PL_DHASH_NEXT;

    XPCNativeSet::DestroyInstance(set);
    return PL_DHASH_REMOVE;
}

static PLDHashOperator
JSClassSweeper(PLDHashTable *table, PLDHashEntryHdr *hdr,
               uint32_t number, void *arg)
{
    XPCNativeScriptableShared* shared =
        ((XPCNativeScriptableSharedMap::Entry*) hdr)->key;
    if (shared->IsMarked()) {
        shared->Unmark();
        return PL_DHASH_NEXT;
    }

    if (arg == UNMARK_ONLY)
        return PL_DHASH_NEXT;

    delete shared;
    return PL_DHASH_REMOVE;
}

static PLDHashOperator
DyingProtoKiller(PLDHashTable *table, PLDHashEntryHdr *hdr,
                 uint32_t number, void *arg)
{
    XPCWrappedNativeProto* proto =
        (XPCWrappedNativeProto*)((PLDHashEntryStub*)hdr)->key;
    delete proto;
    return PL_DHASH_REMOVE;
}

static PLDHashOperator
DetachedWrappedNativeProtoMarker(PLDHashTable *table, PLDHashEntryHdr *hdr,
                                 uint32_t number, void *arg)
{
    XPCWrappedNativeProto* proto =
        (XPCWrappedNativeProto*)((PLDHashEntryStub*)hdr)->key;

    proto->Mark();
    return PL_DHASH_NEXT;
}

bool
XPCJSRuntime::CustomContextCallback(JSContext *cx, unsigned operation)
{
    if (operation == JSCONTEXT_NEW) {
        if (!OnJSContextNew(cx)) {
            return false;
        }
    } else if (operation == JSCONTEXT_DESTROY) {
        delete XPCContext::GetXPCContext(cx);
    }

    nsTArray<xpcContextCallback> callbacks(extraContextCallbacks);
    for (uint32_t i = 0; i < callbacks.Length(); ++i) {
        if (!callbacks[i](cx, operation)) {
            return false;
        }
    }

    return true;
}

class AsyncFreeSnowWhite : public nsRunnable
{
public:
  NS_IMETHOD Run()
  {
      TimeStamp start = TimeStamp::Now();
      bool hadSnowWhiteObjects = nsCycleCollector_doDeferredDeletion();
      Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_ASYNC_SNOW_WHITE_FREEING,
                            uint32_t((TimeStamp::Now() - start).ToMilliseconds()));
      if (hadSnowWhiteObjects && !mContinuation) {
          mContinuation = true;
          if (NS_FAILED(NS_DispatchToCurrentThread(this))) {
              mActive = false;
          }
      } else {
          mActive = false;
      }
      return NS_OK;
  }

  void Dispatch(bool aContinuation = false)
  {
      if (mContinuation) {
          mContinuation = aContinuation;
      }
      if (!mActive && NS_SUCCEEDED(NS_DispatchToCurrentThread(this))) {
          mActive = true;
      }
  }

  AsyncFreeSnowWhite() : mContinuation(false), mActive(false) {}

public:
  bool mContinuation;
  bool mActive;
};

namespace xpc {

static uint32_t kLivingAdopters = 0;

void
RecordAdoptedNode(JSCompartment *c)
{
    CompartmentPrivate *priv = EnsureCompartmentPrivate(c);
    if (!priv->adoptedNode) {
        priv->adoptedNode = true;
        ++kLivingAdopters;
    }
}

void
RecordDonatedNode(JSCompartment *c)
{
    EnsureCompartmentPrivate(c)->donatedNode = true;
}

CompartmentPrivate::~CompartmentPrivate()
{
    MOZ_COUNT_DTOR(xpc::CompartmentPrivate);

    Telemetry::Accumulate(Telemetry::COMPARTMENT_ADOPTED_NODE, adoptedNode);
    Telemetry::Accumulate(Telemetry::COMPARTMENT_DONATED_NODE, donatedNode);
    if (adoptedNode)
        --kLivingAdopters;
}

static bool
TryParseLocationURICandidate(const nsACString& uristr,
                             CompartmentPrivate::LocationHint aLocationHint,
                             nsIURI** aURI)
{
    static NS_NAMED_LITERAL_CSTRING(kGRE, "resource://gre/");
    static NS_NAMED_LITERAL_CSTRING(kToolkit, "chrome://global/");
    static NS_NAMED_LITERAL_CSTRING(kBrowser, "chrome://browser/");

    if (aLocationHint == CompartmentPrivate::LocationHintAddon) {
        // Blacklist some known locations which are clearly not add-on related.
        if (StringBeginsWith(uristr, kGRE) ||
            StringBeginsWith(uristr, kToolkit) ||
            StringBeginsWith(uristr, kBrowser))
            return false;
    }

    nsCOMPtr<nsIURI> uri;
    if (NS_FAILED(NS_NewURI(getter_AddRefs(uri), uristr)))
        return false;

    nsAutoCString scheme;
    if (NS_FAILED(uri->GetScheme(scheme)))
        return false;

    // Cannot really map data: and blob:.
    // Also, data: URIs are pretty memory hungry, which is kinda bad
    // for memory reporter use.
    if (scheme.EqualsLiteral("data") || scheme.EqualsLiteral("blob"))
        return false;

    uri.forget(aURI);
    return true;
}

bool CompartmentPrivate::TryParseLocationURI(CompartmentPrivate::LocationHint aLocationHint,
                                             nsIURI **aURI)
{
    if (!aURI)
        return false;

    // Need to parse the URI.
    if (location.IsEmpty())
        return false;

    // Handle Sandbox location strings.
    // A sandbox string looks like this:
    // <sandboxName> (from: <js-stack-frame-filename>:<lineno>)
    // where <sandboxName> is user-provided via Cu.Sandbox()
    // and <js-stack-frame-filename> and <lineno> is the stack frame location
    // from where Cu.Sandbox was called.
    // <js-stack-frame-filename> furthermore is "free form", often using a
    // "uri -> uri -> ..." chain. The following code will and must handle this
    // common case.
    // It should be noted that other parts of the code may already rely on the
    // "format" of these strings, such as the add-on SDK.

    static const nsDependentCString from("(from: ");
    static const nsDependentCString arrow(" -> ");
    static const size_t fromLength = from.Length();
    static const size_t arrowLength = arrow.Length();

    // See: XPCComponents.cpp#AssembleSandboxMemoryReporterName
    int32_t idx = location.Find(from);
    if (idx < 0)
        return TryParseLocationURICandidate(location, aLocationHint, aURI);


    // When parsing we're looking for the right-most URI. This URI may be in
    // <sandboxName>, so we try this first.
    if (TryParseLocationURICandidate(Substring(location, 0, idx), aLocationHint,
                                     aURI))
        return true;

    // Not in <sandboxName> so we need to inspect <js-stack-frame-filename> and
    // the chain that is potentially contained within and grab the rightmost
    // item that is actually a URI.

    // First, hack off the :<lineno>) part as well
    int32_t ridx = location.RFind(NS_LITERAL_CSTRING(":"));
    nsAutoCString chain(Substring(location, idx + fromLength,
                                  ridx - idx - fromLength));

    // Loop over the "->" chain. This loop also works for non-chains, or more
    // correctly chains with only one item.
    for (;;) {
        idx = chain.RFind(arrow);
        if (idx < 0) {
            // This is the last chain item. Try to parse what is left.
            return TryParseLocationURICandidate(chain, aLocationHint, aURI);
        }

        // Try to parse current chain item
        if (TryParseLocationURICandidate(Substring(chain, idx + arrowLength),
                                         aLocationHint, aURI))
            return true;

        // Current chain item couldn't be parsed.
        // Strip current item and continue.
        chain = Substring(chain, 0, idx);
    }
    MOZ_ASSUME_UNREACHABLE("Chain parser loop does not terminate");
}

CompartmentPrivate*
EnsureCompartmentPrivate(JSObject *obj)
{
    return EnsureCompartmentPrivate(js::GetObjectCompartment(obj));
}

CompartmentPrivate*
EnsureCompartmentPrivate(JSCompartment *c)
{
    CompartmentPrivate *priv = GetCompartmentPrivate(c);
    if (priv)
        return priv;
    priv = new CompartmentPrivate(c);
    JS_SetCompartmentPrivate(c, priv);
    return priv;
}

XPCWrappedNativeScope*
MaybeGetObjectScope(JSObject *obj)
{
    MOZ_ASSERT(obj);
    JSCompartment *compartment = js::GetObjectCompartment(obj);

    MOZ_ASSERT(compartment);
    CompartmentPrivate *priv = GetCompartmentPrivate(compartment);
    if (!priv)
        return nullptr;

    return priv->scope;
}

static bool
PrincipalImmuneToScriptPolicy(nsIPrincipal* aPrincipal)
{
    // System principal gets a free pass.
    if (nsXPConnect::SecurityManager()->IsSystemPrincipal(aPrincipal))
        return true;

    // nsExpandedPrincipal gets a free pass.
    nsCOMPtr<nsIExpandedPrincipal> ep = do_QueryInterface(aPrincipal);
    if (ep)
        return true;

    // Check whether our URI is an "about:" URI that allows scripts.  If it is,
    // we need to allow JS to run.
    nsCOMPtr<nsIURI> principalURI;
    aPrincipal->GetURI(getter_AddRefs(principalURI));
    MOZ_ASSERT(principalURI);
    bool isAbout;
    nsresult rv = principalURI->SchemeIs("about", &isAbout);
    if (NS_SUCCEEDED(rv) && isAbout) {
        nsCOMPtr<nsIAboutModule> module;
        rv = NS_GetAboutModule(principalURI, getter_AddRefs(module));
        if (NS_SUCCEEDED(rv)) {
            uint32_t flags;
            rv = module->GetURIFlags(principalURI, &flags);
            if (NS_SUCCEEDED(rv) &&
                (flags & nsIAboutModule::ALLOW_SCRIPT)) {
                return true;
            }
        }
    }

    return false;
}

Scriptability::Scriptability(JSCompartment *c) : mScriptBlocks(0)
                                               , mDocShellAllowsScript(true)
                                               , mScriptBlockedByPolicy(false)
{
    nsIPrincipal *prin = nsJSPrincipals::get(JS_GetCompartmentPrincipals(c));
    mImmuneToScriptPolicy = PrincipalImmuneToScriptPolicy(prin);

    // If we're not immune, we should have a real principal with a codebase URI.
    // Check the URI against the new-style domain policy.
    if (!mImmuneToScriptPolicy) {
        nsCOMPtr<nsIURI> codebase;
        nsresult rv = prin->GetURI(getter_AddRefs(codebase));
        bool policyAllows;
        if (NS_SUCCEEDED(rv) && codebase &&
            NS_SUCCEEDED(nsXPConnect::SecurityManager()->PolicyAllowsScript(codebase, &policyAllows)))
        {
            mScriptBlockedByPolicy = !policyAllows;
        } else {
            // Something went wrong - be safe and block script.
            mScriptBlockedByPolicy = true;
        }
    }
}

bool
Scriptability::Allowed()
{
    return mDocShellAllowsScript && !mScriptBlockedByPolicy &&
           mScriptBlocks == 0;
}

bool
Scriptability::IsImmuneToScriptPolicy()
{
    return mImmuneToScriptPolicy;
}

void
Scriptability::Block()
{
    ++mScriptBlocks;
}

void
Scriptability::Unblock()
{
    MOZ_ASSERT(mScriptBlocks > 0);
    --mScriptBlocks;
}

void
Scriptability::SetDocShellAllowsScript(bool aAllowed)
{
    mDocShellAllowsScript = aAllowed || mImmuneToScriptPolicy;
}

/* static */
Scriptability&
Scriptability::Get(JSObject *aScope)
{
    return EnsureCompartmentPrivate(aScope)->scriptability;
}

bool
IsContentXBLScope(JSCompartment *compartment)
{
    // We always eagerly create compartment privates for XBL scopes.
    CompartmentPrivate *priv = GetCompartmentPrivate(compartment);
    if (!priv || !priv->scope)
        return false;
    return priv->scope->IsContentXBLScope();
}

bool
IsInContentXBLScope(JSObject *obj)
{
    return IsContentXBLScope(js::GetObjectCompartment(obj));
}

bool
IsUniversalXPConnectEnabled(JSCompartment *compartment)
{
    CompartmentPrivate *priv = GetCompartmentPrivate(compartment);
    if (!priv)
        return false;
    return priv->universalXPConnectEnabled;
}

bool
IsUniversalXPConnectEnabled(JSContext *cx)
{
    JSCompartment *compartment = js::GetContextCompartment(cx);
    if (!compartment)
        return false;
    return IsUniversalXPConnectEnabled(compartment);
}

bool
EnableUniversalXPConnect(JSContext *cx)
{
    JSCompartment *compartment = js::GetContextCompartment(cx);
    if (!compartment)
        return true;
    // Never set universalXPConnectEnabled on a chrome compartment - it confuses
    // the security wrapping code.
    if (AccessCheck::isChrome(compartment))
        return true;
    CompartmentPrivate *priv = GetCompartmentPrivate(compartment);
    if (!priv)
        return true;
    priv->universalXPConnectEnabled = true;

    // Recompute all the cross-compartment wrappers leaving the newly-privileged
    // compartment.
    bool ok = js::RecomputeWrappers(cx, js::SingleCompartment(compartment),
                                    js::AllCompartments());
    NS_ENSURE_TRUE(ok, false);

    // The Components object normally isn't defined for unprivileged web content,
    // but we define it when UniversalXPConnect is enabled to support legacy
    // tests.
    XPCWrappedNativeScope *scope = priv->scope;
    if (!scope)
        return true;
    scope->ForcePrivilegedComponents();
    return scope->AttachComponentsObject(cx);
}

JSObject *
GetJunkScope()
{
    XPCJSRuntime *self = nsXPConnect::GetRuntimeInstance();
    NS_ENSURE_TRUE(self, nullptr);
    return self->GetJunkScope();
}

nsIGlobalObject *
GetJunkScopeGlobal()
{
    JSObject *junkScope = GetJunkScope();
    // GetJunkScope would ideally never fail, currently it is not yet the case
    // unfortunately...(see Bug 874158)
    if (!junkScope)
        return nullptr;
    return GetNativeForGlobal(junkScope);
}

JSObject *
GetCompilationScope()
{
    XPCJSRuntime *self = nsXPConnect::GetRuntimeInstance();
    NS_ENSURE_TRUE(self, nullptr);
    return self->GetCompilationScope();
}

JSObject *
GetSafeJSContextGlobal()
{
    return XPCJSRuntime::Get()->GetJSContextStack()->GetSafeJSContextGlobal();
}

nsGlobalWindow*
WindowOrNull(JSObject *aObj)
{
    MOZ_ASSERT(aObj);
    MOZ_ASSERT(!js::IsWrapper(aObj));

    // This will always return null until we have Window on WebIDL bindings,
    // at which point it will do the right thing.
    if (!IS_WN_CLASS(js::GetObjectClass(aObj))) {
        nsGlobalWindow* win = nullptr;
        UNWRAP_OBJECT(Window, aObj, win);
        return win;
    }

    nsISupports* supports = XPCWrappedNative::Get(aObj)->GetIdentityObject();
    nsCOMPtr<nsPIDOMWindow> piWin = do_QueryInterface(supports);
    if (!piWin)
        return nullptr;
    return static_cast<nsGlobalWindow*>(piWin.get());
}

nsGlobalWindow*
WindowGlobalOrNull(JSObject *aObj)
{
    MOZ_ASSERT(aObj);
    JSObject *glob = js::GetGlobalForObjectCrossCompartment(aObj);

    return WindowOrNull(glob);
}

}

static void
CompartmentDestroyedCallback(JSFreeOp *fop, JSCompartment *compartment)
{
    // NB - This callback may be called in JS_DestroyRuntime, which happens
    // after the XPCJSRuntime has been torn down.

    // Get the current compartment private into an AutoPtr (which will do the
    // cleanup for us), and null out the private (which may already be null).
    nsAutoPtr<CompartmentPrivate> priv(GetCompartmentPrivate(compartment));
    JS_SetCompartmentPrivate(compartment, nullptr);
}

void XPCJSRuntime::TraceNativeBlackRoots(JSTracer* trc)
{
    // Skip this part if XPConnect is shutting down. We get into
    // bad locking problems with the thread iteration otherwise.
    if (!nsXPConnect::XPConnect()->IsShuttingDown()) {
        // Trace those AutoMarkingPtr lists!
        if (AutoMarkingPtr *roots = Get()->mAutoRoots)
            roots->TraceJSAll(trc);
    }

    // XPCJSObjectHolders don't participate in cycle collection, so always
    // trace them here.
    XPCRootSetElem *e;
    for (e = mObjectHolderRoots; e; e = e->GetNextRoot())
        static_cast<XPCJSObjectHolder*>(e)->TraceJS(trc);

    dom::TraceBlackJS(trc, JS_GetGCParameter(Runtime(), JSGC_NUMBER),
                      nsXPConnect::XPConnect()->IsShuttingDown());
}

void XPCJSRuntime::TraceAdditionalNativeGrayRoots(JSTracer *trc)
{
    XPCWrappedNativeScope::TraceWrappedNativesInAllScopes(trc, this);

    for (XPCRootSetElem *e = mVariantRoots; e ; e = e->GetNextRoot())
        static_cast<XPCTraceableVariant*>(e)->TraceJS(trc);

    for (XPCRootSetElem *e = mWrappedJSRoots; e ; e = e->GetNextRoot())
        static_cast<nsXPCWrappedJS*>(e)->TraceJS(trc);
}

// static
void
XPCJSRuntime::SuspectWrappedNative(XPCWrappedNative *wrapper,
                                   nsCycleCollectionNoteRootCallback &cb)
{
    if (!wrapper->IsValid() || wrapper->IsWrapperExpired())
        return;

    MOZ_ASSERT(NS_IsMainThread(),
               "Suspecting wrapped natives from non-main thread");

    // Only record objects that might be part of a cycle as roots, unless
    // the callback wants all traces (a debug feature).
    JSObject* obj = wrapper->GetFlatJSObjectPreserveColor();
    if (xpc_IsGrayGCThing(obj) || cb.WantAllTraces())
        cb.NoteJSRoot(obj);
}

void
XPCJSRuntime::TraverseAdditionalNativeRoots(nsCycleCollectionNoteRootCallback &cb)
{
    XPCWrappedNativeScope::SuspectAllWrappers(this, cb);

    for (XPCRootSetElem *e = mVariantRoots; e ; e = e->GetNextRoot()) {
        XPCTraceableVariant* v = static_cast<XPCTraceableVariant*>(e);
        if (nsCCUncollectableMarker::InGeneration(cb,
                                                  v->CCGeneration())) {
           jsval val = v->GetJSValPreserveColor();
           if (val.isObject() && !xpc_IsGrayGCThing(&val.toObject()))
               continue;
        }
        cb.NoteXPCOMRoot(v);
    }

    for (XPCRootSetElem *e = mWrappedJSRoots; e ; e = e->GetNextRoot()) {
        cb.NoteXPCOMRoot(ToSupports(static_cast<nsXPCWrappedJS*>(e)));
    }
}

void
XPCJSRuntime::UnmarkSkippableJSHolders()
{
    CycleCollectedJSRuntime::UnmarkSkippableJSHolders();
}

void
XPCJSRuntime::PrepareForForgetSkippable()
{
    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
    if (obs) {
        obs->NotifyObservers(nullptr, "cycle-collector-forget-skippable", nullptr);
    }
}

void
XPCJSRuntime::BeginCycleCollectionCallback()
{
    nsJSContext::BeginCycleCollectionCallback();

    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
    if (obs) {
        obs->NotifyObservers(nullptr, "cycle-collector-begin", nullptr);
    }
}

void
XPCJSRuntime::EndCycleCollectionCallback(CycleCollectorResults &aResults)
{
    nsJSContext::EndCycleCollectionCallback(aResults);

    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
    if (obs) {
        obs->NotifyObservers(nullptr, "cycle-collector-end", nullptr);
    }
}

void
XPCJSRuntime::DispatchDeferredDeletion(bool aContinuation)
{
    mAsyncSnowWhiteFreer->Dispatch(aContinuation);
}

void
xpc_UnmarkSkippableJSHolders()
{
    if (nsXPConnect::XPConnect()->GetRuntime()) {
        nsXPConnect::XPConnect()->GetRuntime()->UnmarkSkippableJSHolders();
    }
}

template<class T> static void
DoDeferredRelease(nsTArray<T> &array)
{
    while (1) {
        uint32_t count = array.Length();
        if (!count) {
            array.Compact();
            break;
        }
        T wrapper = array[count-1];
        array.RemoveElementAt(count-1);
        NS_RELEASE(wrapper);
    }
}

/* static */ void
XPCJSRuntime::GCSliceCallback(JSRuntime *rt,
                              JS::GCProgress progress,
                              const JS::GCDescription &desc)
{
    XPCJSRuntime *self = nsXPConnect::GetRuntimeInstance();
    if (!self)
        return;

#ifdef MOZ_CRASHREPORTER
    CrashReporter::SetGarbageCollecting(progress == JS::GC_CYCLE_BEGIN ||
                                        progress == JS::GC_SLICE_BEGIN);
#endif

    if (self->mPrevGCSliceCallback)
        (*self->mPrevGCSliceCallback)(rt, progress, desc);
}

void
XPCJSRuntime::CustomGCCallback(JSGCStatus status)
{
    // Record kLivingAdopters once per GC to approximate time sampling during
    // periods of activity.
    if (status == JSGC_BEGIN) {
        Telemetry::Accumulate(Telemetry::COMPARTMENT_LIVING_ADOPTERS,
                              kLivingAdopters);
    }

    nsTArray<xpcGCCallback> callbacks(extraGCCallbacks);
    for (uint32_t i = 0; i < callbacks.Length(); ++i)
        callbacks[i](status);
}

/* static */ void
XPCJSRuntime::FinalizeCallback(JSFreeOp *fop,
                               JSFinalizeStatus status,
                               bool isCompartmentGC,
                               void *data)
{
    XPCJSRuntime* self = nsXPConnect::GetRuntimeInstance();
    if (!self)
        return;

    switch (status) {
        case JSFINALIZE_GROUP_START:
        {
            MOZ_ASSERT(!self->mDoingFinalization, "bad state");

            MOZ_ASSERT(!self->mGCIsRunning, "bad state");
            self->mGCIsRunning = true;

            nsTArray<nsXPCWrappedJS*>* dyingWrappedJSArray =
                &self->mWrappedJSToReleaseArray;

            // Add any wrappers whose JSObjects are to be finalized to
            // this array. Note that we do not want to be changing the
            // refcount of these wrappers.
            // We add them to the array now and Release the array members
            // later to avoid the posibility of doing any JS GCThing
            // allocations during the gc cycle.
            self->mWrappedJSMap->FindDyingJSObjects(dyingWrappedJSArray);

            // Find dying scopes.
            XPCWrappedNativeScope::StartFinalizationPhaseOfGC(fop, self);

            self->mDoingFinalization = true;
            break;
        }
        case JSFINALIZE_GROUP_END:
        {
            MOZ_ASSERT(self->mDoingFinalization, "bad state");
            self->mDoingFinalization = false;

            // Release all the members whose JSObjects are now known
            // to be dead.
            DoDeferredRelease(self->mWrappedJSToReleaseArray);

            // Sweep scopes needing cleanup
            XPCWrappedNativeScope::FinishedFinalizationPhaseOfGC();

            MOZ_ASSERT(self->mGCIsRunning, "bad state");
            self->mGCIsRunning = false;

            break;
        }
        case JSFINALIZE_COLLECTION_END:
        {
            MOZ_ASSERT(!self->mGCIsRunning, "bad state");
            self->mGCIsRunning = true;

            // We use this occasion to mark and sweep NativeInterfaces,
            // NativeSets, and the WrappedNativeJSClasses...

            // Do the marking...
            XPCWrappedNativeScope::MarkAllWrappedNativesAndProtos();

            self->mDetachedWrappedNativeProtoMap->
                Enumerate(DetachedWrappedNativeProtoMarker, nullptr);

            DOM_MarkInterfaces();

            // Mark the sets used in the call contexts. There is a small
            // chance that a wrapper's set will change *while* a call is
            // happening which uses that wrapper's old interfface set. So,
            // we need to do this marking to avoid collecting those sets
            // that might no longer be otherwise reachable from the wrappers
            // or the wrapperprotos.

            // Skip this part if XPConnect is shutting down. We get into
            // bad locking problems with the thread iteration otherwise.
            if (!nsXPConnect::XPConnect()->IsShuttingDown()) {

                // Mark those AutoMarkingPtr lists!
                if (AutoMarkingPtr *roots = Get()->mAutoRoots)
                    roots->MarkAfterJSFinalizeAll();

                XPCCallContext* ccxp = XPCJSRuntime::Get()->GetCallContext();
                while (ccxp) {
                    // Deal with the strictness of callcontext that
                    // complains if you ask for a set when
                    // it is in a state where the set could not
                    // possibly be valid.
                    if (ccxp->CanGetSet()) {
                        XPCNativeSet* set = ccxp->GetSet();
                        if (set)
                            set->Mark();
                    }
                    if (ccxp->CanGetInterface()) {
                        XPCNativeInterface* iface = ccxp->GetInterface();
                        if (iface)
                            iface->Mark();
                    }
                    ccxp = ccxp->GetPrevCallContext();
                }
            }

            // Do the sweeping. During a compartment GC, only
            // WrappedNativeProtos in collected compartments will be
            // marked. Therefore, some reachable NativeInterfaces will not be
            // marked, so it is not safe to sweep them. We still need to unmark
            // them, since the ones pointed to by WrappedNativeProtos in a
            // compartment being collected will be marked.
            //
            // Ideally, if NativeInterfaces from different compartments were
            // kept separate, we could sweep only the ones belonging to
            // compartments being collected. Currently, though, NativeInterfaces
            // are shared between compartments. This ought to be fixed.
            void *sweepArg = isCompartmentGC ? UNMARK_ONLY : UNMARK_AND_SWEEP;

            // We don't want to sweep the JSClasses at shutdown time.
            // At this point there may be JSObjects using them that have
            // been removed from the other maps.
            if (!nsXPConnect::XPConnect()->IsShuttingDown()) {
                self->mNativeScriptableSharedMap->
                    Enumerate(JSClassSweeper, sweepArg);
            }

            if (!isCompartmentGC) {
                self->mClassInfo2NativeSetMap->
                    Enumerate(NativeUnMarkedSetRemover, nullptr);
            }

            self->mNativeSetMap->
                Enumerate(NativeSetSweeper, sweepArg);

            self->mIID2NativeInterfaceMap->
                Enumerate(NativeInterfaceSweeper, sweepArg);

#ifdef DEBUG
            XPCWrappedNativeScope::ASSERT_NoInterfaceSetsAreMarked();
#endif

            // Now we are going to recycle any unused WrappedNativeTearoffs.
            // We do this by iterating all the live callcontexts
            // and marking the tearoffs in use. And then we
            // iterate over all the WrappedNative wrappers and sweep their
            // tearoffs.
            //
            // This allows us to perhaps minimize the growth of the
            // tearoffs. And also makes us not hold references to interfaces
            // on our wrapped natives that we are not actually using.
            //
            // XXX We may decide to not do this on *every* gc cycle.

            // Skip this part if XPConnect is shutting down. We get into
            // bad locking problems with the thread iteration otherwise.
            if (!nsXPConnect::XPConnect()->IsShuttingDown()) {
                // Do the marking...

                XPCCallContext* ccxp = XPCJSRuntime::Get()->GetCallContext();
                while (ccxp) {
                    // Deal with the strictness of callcontext that
                    // complains if you ask for a tearoff when
                    // it is in a state where the tearoff could not
                    // possibly be valid.
                    if (ccxp->CanGetTearOff()) {
                        XPCWrappedNativeTearOff* to =
                            ccxp->GetTearOff();
                        if (to)
                            to->Mark();
                    }
                    ccxp = ccxp->GetPrevCallContext();
                }

                // Do the sweeping...
                XPCWrappedNativeScope::SweepAllWrappedNativeTearOffs();
            }

            // Now we need to kill the 'Dying' XPCWrappedNativeProtos.
            // We transfered these native objects to this table when their
            // JSObject's were finalized. We did not destroy them immediately
            // at that point because the ordering of JS finalization is not
            // deterministic and we did not yet know if any wrappers that
            // might still be referencing the protos where still yet to be
            // finalized and destroyed. We *do* know that the protos'
            // JSObjects would not have been finalized if there were any
            // wrappers that referenced the proto but where not themselves
            // slated for finalization in this gc cycle. So... at this point
            // we know that any and all wrappers that might have been
            // referencing the protos in the dying list are themselves dead.
            // So, we can safely delete all the protos in the list.

            self->mDyingWrappedNativeProtoMap->
                Enumerate(DyingProtoKiller, nullptr);

            MOZ_ASSERT(self->mGCIsRunning, "bad state");
            self->mGCIsRunning = false;

            break;
        }
    }
}

static void WatchdogMain(void *arg);
class Watchdog;
class WatchdogManager;
class AutoLockWatchdog {
    Watchdog* const mWatchdog;
  public:
    AutoLockWatchdog(Watchdog* aWatchdog);
    ~AutoLockWatchdog();
};

class Watchdog
{
  public:
    Watchdog(WatchdogManager *aManager)
      : mManager(aManager)
      , mLock(nullptr)
      , mWakeup(nullptr)
      , mThread(nullptr)
      , mHibernating(false)
      , mInitialized(false)
      , mShuttingDown(false)
    {}
    ~Watchdog() { MOZ_ASSERT(!Initialized()); }

    WatchdogManager* Manager() { return mManager; }
    bool Initialized() { return mInitialized; }
    bool ShuttingDown() { return mShuttingDown; }
    PRLock *GetLock() { return mLock; }
    bool Hibernating() { return mHibernating; }
    void WakeUp()
    {
        MOZ_ASSERT(Initialized());
        MOZ_ASSERT(Hibernating());
        mHibernating = false;
        PR_NotifyCondVar(mWakeup);
    }

    //
    // Invoked by the main thread only.
    //

    void Init()
    {
        MOZ_ASSERT(NS_IsMainThread());
        mLock = PR_NewLock();
        if (!mLock)
            NS_RUNTIMEABORT("PR_NewLock failed.");
        mWakeup = PR_NewCondVar(mLock);
        if (!mWakeup)
            NS_RUNTIMEABORT("PR_NewCondVar failed.");

        {
            AutoLockWatchdog lock(this);

            mThread = PR_CreateThread(PR_USER_THREAD, WatchdogMain, this,
                                      PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD,
                                      PR_UNJOINABLE_THREAD, 0);
            if (!mThread)
                NS_RUNTIMEABORT("PR_CreateThread failed!");

            // WatchdogMain acquires the lock and then asserts mInitialized. So
            // make sure to set mInitialized before releasing the lock here so
            // that it's atomic with the creation of the thread.
            mInitialized = true;
        }
    }

    void Shutdown()
    {
        MOZ_ASSERT(NS_IsMainThread());
        MOZ_ASSERT(Initialized());
        {   // Scoped lock.
            AutoLockWatchdog lock(this);

            // Signal to the watchdog thread that it's time to shut down.
            mShuttingDown = true;

            // Wake up the watchdog, and wait for it to call us back.
            PR_NotifyCondVar(mWakeup);
            PR_WaitCondVar(mWakeup, PR_INTERVAL_NO_TIMEOUT);
            MOZ_ASSERT(!mShuttingDown);
        }

        // Destroy state.
        mThread = nullptr;
        PR_DestroyCondVar(mWakeup);
        mWakeup = nullptr;
        PR_DestroyLock(mLock);
        mLock = nullptr;

        // All done.
        mInitialized = false;
    }

    //
    // Invoked by the watchdog thread only.
    //

    void Hibernate()
    {
        MOZ_ASSERT(!NS_IsMainThread());
        mHibernating = true;
        Sleep(PR_INTERVAL_NO_TIMEOUT);
    }
    void Sleep(PRIntervalTime timeout)
    {
        MOZ_ASSERT(!NS_IsMainThread());
        MOZ_ALWAYS_TRUE(PR_WaitCondVar(mWakeup, timeout) == PR_SUCCESS);
    }
    void Finished()
    {
        MOZ_ASSERT(!NS_IsMainThread());
        mShuttingDown = false;
        PR_NotifyCondVar(mWakeup);
    }

  private:
    WatchdogManager *mManager;

    PRLock *mLock;
    PRCondVar *mWakeup;
    PRThread *mThread;
    bool mHibernating;
    bool mInitialized;
    bool mShuttingDown;
};

#ifdef MOZ_NUWA_PROCESS
#include "ipc/Nuwa.h"
#endif

class WatchdogManager : public nsIObserver
{
  public:

    NS_DECL_ISUPPORTS
    WatchdogManager(XPCJSRuntime *aRuntime) : mRuntime(aRuntime)
                                            , mRuntimeState(RUNTIME_INACTIVE)
    {
        // All the timestamps start at zero except for runtime state change.
        PodArrayZero(mTimestamps);
        mTimestamps[TimestampRuntimeStateChange] = PR_Now();

        // Enable the watchdog, if appropriate.
        RefreshWatchdog();

        // Register ourselves as an observer to get updates on the pref.
        mozilla::Preferences::AddStrongObserver(this, "dom.use_watchdog");
    }
    virtual ~WatchdogManager()
    {
        // Shutting down the watchdog requires context-switching to the watchdog
        // thread, which isn't great to do in a destructor. So we require
        // consumers to shut it down manually before releasing it.
        MOZ_ASSERT(!mWatchdog);
        mozilla::Preferences::RemoveObserver(this, "dom.use_watchdog");
    }

    NS_IMETHOD Observe(nsISupports* aSubject, const char* aTopic,
                       const char16_t* aData)
    {
        RefreshWatchdog();
        return NS_OK;
    }

    // Runtime statistics. These live on the watchdog manager, are written
    // from the main thread, and are read from the watchdog thread (holding
    // the lock in each case).
    void
    RecordRuntimeActivity(bool active)
    {
        // The watchdog reads this state, so acquire the lock before writing it.
        MOZ_ASSERT(NS_IsMainThread());
        Maybe<AutoLockWatchdog> lock;
        if (mWatchdog)
            lock.construct(mWatchdog);

        // Write state.
        mTimestamps[TimestampRuntimeStateChange] = PR_Now();
        mRuntimeState = active ? RUNTIME_ACTIVE : RUNTIME_INACTIVE;

        // The watchdog may be hibernating, waiting for the runtime to go
        // active. Wake it up if necessary.
        if (active && mWatchdog && mWatchdog->Hibernating())
            mWatchdog->WakeUp();
    }
    bool IsRuntimeActive() { return mRuntimeState == RUNTIME_ACTIVE; }
    PRTime TimeSinceLastRuntimeStateChange()
    {
        return PR_Now() - GetTimestamp(TimestampRuntimeStateChange);
    }

    // Note - Because of the runtime activity timestamp, these are read and
    // written from both threads.
    void RecordTimestamp(WatchdogTimestampCategory aCategory)
    {
        // The watchdog thread always holds the lock when it runs.
        Maybe<AutoLockWatchdog> maybeLock;
        if (NS_IsMainThread() && mWatchdog)
            maybeLock.construct(mWatchdog);
        mTimestamps[aCategory] = PR_Now();
    }
    PRTime GetTimestamp(WatchdogTimestampCategory aCategory)
    {
        // The watchdog thread always holds the lock when it runs.
        Maybe<AutoLockWatchdog> maybeLock;
        if (NS_IsMainThread() && mWatchdog)
            maybeLock.construct(mWatchdog);
        return mTimestamps[aCategory];
    }

    XPCJSRuntime* Runtime() { return mRuntime; }
    Watchdog* GetWatchdog() { return mWatchdog; }

    void RefreshWatchdog()
    {
        bool wantWatchdog = Preferences::GetBool("dom.use_watchdog", true);
        if (wantWatchdog == !!mWatchdog)
            return;
        if (wantWatchdog)
            StartWatchdog();
        else
            StopWatchdog();
    }

    void StartWatchdog()
    {
        MOZ_ASSERT(!mWatchdog);
        mWatchdog = new Watchdog(this);
        mWatchdog->Init();
    }

    void StopWatchdog()
    {
        MOZ_ASSERT(mWatchdog);
        mWatchdog->Shutdown();
        mWatchdog = nullptr;
    }

  private:
    XPCJSRuntime *mRuntime;
    nsAutoPtr<Watchdog> mWatchdog;

    enum { RUNTIME_ACTIVE, RUNTIME_INACTIVE } mRuntimeState;
    PRTime mTimestamps[TimestampCount];
};

NS_IMPL_ISUPPORTS(WatchdogManager, nsIObserver)

AutoLockWatchdog::AutoLockWatchdog(Watchdog *aWatchdog) : mWatchdog(aWatchdog)
{
    PR_Lock(mWatchdog->GetLock());
}

AutoLockWatchdog::~AutoLockWatchdog()
{
    PR_Unlock(mWatchdog->GetLock());
}

static void
WatchdogMain(void *arg)
{
    PR_SetCurrentThreadName("JS Watchdog");

#ifdef MOZ_NUWA_PROCESS
    if (IsNuwaProcess()) {
        NS_ASSERTION(NuwaMarkCurrentThread != nullptr,
                     "NuwaMarkCurrentThread is undefined!");
        NuwaMarkCurrentThread(nullptr, nullptr);
        NuwaFreezeCurrentThread();
    }
#endif

    Watchdog* self = static_cast<Watchdog*>(arg);
    WatchdogManager* manager = self->Manager();

    // Lock lasts until we return
    AutoLockWatchdog lock(self);

    MOZ_ASSERT(self->Initialized());
    MOZ_ASSERT(!self->ShuttingDown());
    while (!self->ShuttingDown()) {
        // Sleep only 1 second if recently (or currently) active; otherwise, hibernate
        if (manager->IsRuntimeActive() ||
            manager->TimeSinceLastRuntimeStateChange() <= PRTime(2*PR_USEC_PER_SEC))
        {
            self->Sleep(PR_TicksPerSecond());
        } else {
            manager->RecordTimestamp(TimestampWatchdogHibernateStart);
            self->Hibernate();
            manager->RecordTimestamp(TimestampWatchdogHibernateStop);
        }

        // Rise and shine.
        manager->RecordTimestamp(TimestampWatchdogWakeup);

        // Don't request an interrupt callback if activity started less than one second ago.
        // The callback is only used for detecting long running scripts, and triggering the
        // callback from off the main thread can be expensive.
        if (manager->IsRuntimeActive() &&
            manager->TimeSinceLastRuntimeStateChange() >= PRTime(PR_USEC_PER_SEC))
        {
            bool debuggerAttached = false;
            nsCOMPtr<nsIDebug2> dbg = do_GetService("@mozilla.org/xpcom/debug;1");
            if (dbg)
                dbg->GetIsDebuggerAttached(&debuggerAttached);
            if (!debuggerAttached)
                JS_RequestInterruptCallback(manager->Runtime()->Runtime());
        }
    }

    // Tell the manager that we've shut down.
    self->Finished();
}

PRTime
XPCJSRuntime::GetWatchdogTimestamp(WatchdogTimestampCategory aCategory)
{
    return mWatchdogManager->GetTimestamp(aCategory);
}

void
xpc::SimulateActivityCallback(bool aActive)
{
    XPCJSRuntime::ActivityCallback(XPCJSRuntime::Get(), aActive);
}

// static
JSContext*
XPCJSRuntime::DefaultJSContextCallback(JSRuntime *rt)
{
    MOZ_ASSERT(rt == Get()->Runtime());
    return Get()->GetJSContextStack()->GetSafeJSContext();
}

// static
void
XPCJSRuntime::ActivityCallback(void *arg, bool active)
{
    XPCJSRuntime* self = static_cast<XPCJSRuntime*>(arg);
    self->mWatchdogManager->RecordRuntimeActivity(active);
}

// static
//
// JS-CTypes creates and caches a JSContext that it uses when executing JS
// callbacks. When we're notified that ctypes is about to call into some JS,
// push the cx to maintain the integrity of the context stack.
void
XPCJSRuntime::CTypesActivityCallback(JSContext *cx, js::CTypesActivityType type)
{
  if (type == js::CTYPES_CALLBACK_BEGIN) {
    if (!xpc::PushJSContextNoScriptContext(cx))
      MOZ_CRASH();
  } else if (type == js::CTYPES_CALLBACK_END) {
    xpc::PopJSContextNoScriptContext();
  }
}

// static
bool
XPCJSRuntime::InterruptCallback(JSContext *cx)
{
    XPCJSRuntime *self = XPCJSRuntime::Get();

    // If this is the first time the interrupt callback has fired since we last
    // returned to the event loop, mark the checkpoint.
    if (self->mSlowScriptCheckpoint.IsNull()) {
        self->mSlowScriptCheckpoint = TimeStamp::NowLoRes();
        return true;
    }

    // Sometimes we get called back during XPConnect initialization, before Gecko
    // has finished bootstrapping. Avoid crashing in nsContentUtils below.
    if (!nsContentUtils::IsInitialized())
        return true;

    // This is at least the second interrupt callback we've received since
    // returning to the event loop. See how long it's been, and what the limit
    // is.
    TimeDuration duration = TimeStamp::NowLoRes() - self->mSlowScriptCheckpoint;
    bool chrome = nsContentUtils::IsCallerChrome();
    const char *prefName = chrome ? "dom.max_chrome_script_run_time"
                                  : "dom.max_script_run_time";
    int32_t limit = Preferences::GetInt(prefName, chrome ? 20 : 10);

    // If there's no limit, or we're within the limit, let it go.
    if (limit == 0 || duration.ToSeconds() < limit)
        return true;

    //
    // This has gone on long enough! Time to take action. ;-)
    //

    // Get the DOM window associated with the running script. If the script is
    // running in a non-DOM scope, we have to just let it keep running.
    RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
    nsRefPtr<nsGlobalWindow> win = WindowOrNull(global);
    if (!win && IsSandbox(global)) {
        // If this is a sandbox associated with a DOMWindow via a
        // sandboxPrototype, use that DOMWindow. This supports GreaseMonkey
        // and JetPack content scripts.
        JS::Rooted<JSObject*> proto(cx);
        if (!JS_GetPrototype(cx, global, &proto))
            return false;
        if (proto && IsSandboxPrototypeProxy(proto) &&
            (proto = js::CheckedUnwrap(proto, /* stopAtOuter = */ false)))
        {
            win = WindowGlobalOrNull(proto);
        }
    }
    if (!win)
        return true;

    // Show the prompt to the user, and kill if requested.
    nsGlobalWindow::SlowScriptResponse response = win->ShowSlowScriptDialog();
    if (response == nsGlobalWindow::KillSlowScript)
        return false;

    // The user chose to continue the script. Reset the timer, and disable this
    // machinery with a pref of the user opted out of future slow-script dialogs.
    self->mSlowScriptCheckpoint = TimeStamp::NowLoRes();
    if (response == nsGlobalWindow::AlwaysContinueSlowScript)
        Preferences::SetInt(prefName, 0);

    return true;
}

void
XPCJSRuntime::CustomOutOfMemoryCallback()
{
    if (!Preferences::GetBool("memory.dump_reports_on_oom")) {
        return;
    }

    nsCOMPtr<nsIMemoryInfoDumper> dumper =
        do_GetService("@mozilla.org/memory-info-dumper;1");
    if (!dumper) {
        return;
    }

    // If this fails, it fails silently.
    dumper->DumpMemoryInfoToTempDir(NS_LITERAL_STRING("due-to-JS-OOM"),
                                    /* minimizeMemoryUsage = */ false);
}

void
XPCJSRuntime::CustomLargeAllocationFailureCallback()
{
    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
    if (os) {
        os->NotifyObservers(nullptr, "memory-pressure", MOZ_UTF16("heap-minimize"));
    }
}

size_t
XPCJSRuntime::SizeOfIncludingThis(MallocSizeOf mallocSizeOf)
{
    size_t n = 0;
    n += mallocSizeOf(this);
    n += mWrappedJSMap->SizeOfIncludingThis(mallocSizeOf);
    n += mIID2NativeInterfaceMap->SizeOfIncludingThis(mallocSizeOf);
    n += mClassInfo2NativeSetMap->ShallowSizeOfIncludingThis(mallocSizeOf);
    n += mNativeSetMap->SizeOfIncludingThis(mallocSizeOf);

    n += CycleCollectedJSRuntime::SizeOfExcludingThis(mallocSizeOf);

    // There are other XPCJSRuntime members that could be measured; the above
    // ones have been seen by DMD to be worth measuring.  More stuff may be
    // added later.

    return n;
}

nsString*
XPCJSRuntime::NewShortLivedString()
{
    for (uint32_t i = 0; i < XPCCCX_STRING_CACHE_SIZE; ++i) {
        if (mScratchStrings[i].empty()) {
            mScratchStrings[i].construct();
            return mScratchStrings[i].addr();
        }
    }

    // All our internal string wrappers are used, allocate a new string.
    return new nsString();
}

void
XPCJSRuntime::DeleteShortLivedString(nsString *string)
{
    if (string == &EmptyString() || string == &NullString())
        return;

    for (uint32_t i = 0; i < XPCCCX_STRING_CACHE_SIZE; ++i) {
        if (!mScratchStrings[i].empty() &&
            mScratchStrings[i].addr() == string) {
            // One of our internal strings is no longer in use, mark
            // it as such and free its data.
            mScratchStrings[i].destroy();
            return;
        }
    }

    // We're done with a string that's not one of our internal
    // strings, delete it.
    delete string;
}

/***************************************************************************/

static PLDHashOperator
DetachedWrappedNativeProtoShutdownMarker(PLDHashTable *table, PLDHashEntryHdr *hdr,
                                         uint32_t number, void *arg)
{
    XPCWrappedNativeProto* proto =
        (XPCWrappedNativeProto*)((PLDHashEntryStub*)hdr)->key;

    proto->SystemIsBeingShutDown();
    return PL_DHASH_NEXT;
}

void XPCJSRuntime::DestroyJSContextStack()
{
    delete mJSContextStack;
    mJSContextStack = nullptr;
}

void XPCJSRuntime::SystemIsBeingShutDown()
{
    DOM_ClearInterfaces();

    if (mDetachedWrappedNativeProtoMap)
        mDetachedWrappedNativeProtoMap->
            Enumerate(DetachedWrappedNativeProtoShutdownMarker, nullptr);
}

#define JS_OPTIONS_DOT_STR "javascript.options."

static void
ReloadPrefsCallback(const char *pref, void *data)
{
    XPCJSRuntime *runtime = reinterpret_cast<XPCJSRuntime *>(data);
    JSRuntime *rt = runtime->Runtime();

    bool safeMode = false;
    nsCOMPtr<nsIXULRuntime> xr = do_GetService("@mozilla.org/xre/runtime;1");
    if (xr) {
        xr->GetInSafeMode(&safeMode);
    }

    bool useBaseline = Preferences::GetBool(JS_OPTIONS_DOT_STR "baselinejit") && !safeMode;
    bool useIon = Preferences::GetBool(JS_OPTIONS_DOT_STR "ion") && !safeMode;
    bool useAsmJS = Preferences::GetBool(JS_OPTIONS_DOT_STR "asmjs") && !safeMode;
    bool useNativeRegExp = Preferences::GetBool(JS_OPTIONS_DOT_STR "native_regexp") && !safeMode;

    bool parallelParsing = Preferences::GetBool(JS_OPTIONS_DOT_STR "parallel_parsing");
    bool parallelIonCompilation = Preferences::GetBool(JS_OPTIONS_DOT_STR
                                                       "ion.parallel_compilation");
    bool useBaselineEager = Preferences::GetBool(JS_OPTIONS_DOT_STR
                                                 "baselinejit.unsafe_eager_compilation");
    bool useIonEager = Preferences::GetBool(JS_OPTIONS_DOT_STR "ion.unsafe_eager_compilation");

    sDiscardSystemSource = Preferences::GetBool(JS_OPTIONS_DOT_STR "discardSystemSource");

    JS::RuntimeOptionsRef(rt).setBaseline(useBaseline)
                             .setIon(useIon)
                             .setAsmJS(useAsmJS)
                             .setNativeRegExp(useNativeRegExp);

    JS_SetParallelParsingEnabled(rt, parallelParsing);
    JS_SetParallelIonCompilationEnabled(rt, parallelIonCompilation);
    JS_SetGlobalJitCompilerOption(rt, JSJITCOMPILER_BASELINE_USECOUNT_TRIGGER,
                                  useBaselineEager ? 0 : -1);
    JS_SetGlobalJitCompilerOption(rt, JSJITCOMPILER_ION_USECOUNT_TRIGGER,
                                  useIonEager ? 0 : -1);
}

XPCJSRuntime::~XPCJSRuntime()
{
    // This destructor runs before ~CycleCollectedJSRuntime, which does the
    // actual JS_DestroyRuntime() call. But destroying the runtime triggers
    // one final GC, which can call back into the runtime with various
    // callback if we aren't careful. Null out the relevant callbacks.
    js::SetActivityCallback(Runtime(), nullptr, nullptr);
    JS_RemoveFinalizeCallback(Runtime(), FinalizeCallback);

    // Clear any pending exception.  It might be an XPCWrappedJS, and if we try
    // to destroy it later we will crash.
    SetPendingException(nullptr);

    JS::SetGCSliceCallback(Runtime(), mPrevGCSliceCallback);

    xpc_DelocalizeRuntime(Runtime());

    if (mWatchdogManager->GetWatchdog())
        mWatchdogManager->StopWatchdog();

    if (mCallContext)
        mCallContext->SystemIsBeingShutDown();

    auto rtPrivate = static_cast<PerThreadAtomCache*>(JS_GetRuntimePrivate(Runtime()));
    delete rtPrivate;
    JS_SetRuntimePrivate(Runtime(), nullptr);

    // clean up and destroy maps...
    if (mWrappedJSMap) {
        mWrappedJSMap->ShutdownMarker();
        delete mWrappedJSMap;
        mWrappedJSMap = nullptr;
    }

    if (mWrappedJSClassMap) {
        delete mWrappedJSClassMap;
        mWrappedJSClassMap = nullptr;
    }

    if (mIID2NativeInterfaceMap) {
        delete mIID2NativeInterfaceMap;
        mIID2NativeInterfaceMap = nullptr;
    }

    if (mClassInfo2NativeSetMap) {
        delete mClassInfo2NativeSetMap;
        mClassInfo2NativeSetMap = nullptr;
    }

    if (mNativeSetMap) {
        delete mNativeSetMap;
        mNativeSetMap = nullptr;
    }

    if (mThisTranslatorMap) {
        delete mThisTranslatorMap;
        mThisTranslatorMap = nullptr;
    }

    if (mNativeScriptableSharedMap) {
        delete mNativeScriptableSharedMap;
        mNativeScriptableSharedMap = nullptr;
    }

    if (mDyingWrappedNativeProtoMap) {
        delete mDyingWrappedNativeProtoMap;
        mDyingWrappedNativeProtoMap = nullptr;
    }

    if (mDetachedWrappedNativeProtoMap) {
        delete mDetachedWrappedNativeProtoMap;
        mDetachedWrappedNativeProtoMap = nullptr;
    }

#ifdef MOZ_ENABLE_PROFILER_SPS
    // Tell the profiler that the runtime is gone
    if (PseudoStack *stack = mozilla_get_pseudo_stack())
        stack->sampleRuntime(nullptr);
#endif

#ifdef DEBUG
    for (uint32_t i = 0; i < XPCCCX_STRING_CACHE_SIZE; ++i) {
        MOZ_ASSERT(mScratchStrings[i].empty(), "Short lived string still in use");
    }
#endif

    Preferences::UnregisterCallback(ReloadPrefsCallback, JS_OPTIONS_DOT_STR, this);
}

static void
GetCompartmentName(JSCompartment *c, nsCString &name, bool replaceSlashes)
{
    if (js::IsAtomsCompartment(c)) {
        name.AssignLiteral("atoms");
    } else if (JSPrincipals *principals = JS_GetCompartmentPrincipals(c)) {
        nsJSPrincipals::get(principals)->GetScriptLocation(name);

        // If the compartment's location (name) differs from the principal's
        // script location, append the compartment's location to allow
        // differentiation of multiple compartments owned by the same principal
        // (e.g. components owned by the system or null principal).
        CompartmentPrivate *compartmentPrivate = GetCompartmentPrivate(c);
        if (compartmentPrivate) {
            const nsACString& location = compartmentPrivate->GetLocation();
            if (!location.IsEmpty() && !location.Equals(name)) {
                name.AppendLiteral(", ");
                name.Append(location);
            }
        }

        // A hack: replace forward slashes with '\\' so they aren't
        // treated as path separators.  Users of the reporters
        // (such as about:memory) have to undo this change.
        if (replaceSlashes)
            name.ReplaceChar('/', '\\');
    } else {
        name.AssignLiteral("null-principal");
    }
}

static int64_t
JSMainRuntimeGCHeapDistinguishedAmount()
{
    JSRuntime *rt = nsXPConnect::GetRuntimeInstance()->Runtime();
    return int64_t(JS_GetGCParameter(rt, JSGC_TOTAL_CHUNKS)) *
           js::gc::ChunkSize;
}

static int64_t
JSMainRuntimeTemporaryPeakDistinguishedAmount()
{
    JSRuntime *rt = nsXPConnect::GetRuntimeInstance()->Runtime();
    return JS::PeakSizeOfTemporary(rt);
}

static int64_t
JSMainRuntimeCompartmentsSystemDistinguishedAmount()
{
    JSRuntime *rt = nsXPConnect::GetRuntimeInstance()->Runtime();
    return JS::SystemCompartmentCount(rt);
}

static int64_t
JSMainRuntimeCompartmentsUserDistinguishedAmount()
{
    JSRuntime *rt = nsXPConnect::GetRuntimeInstance()->Runtime();
    return JS::UserCompartmentCount(rt);
}

class JSMainRuntimeTemporaryPeakReporter MOZ_FINAL : public nsIMemoryReporter
{
  public:
    NS_DECL_ISUPPORTS

    NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
                              nsISupports* aData)
    {
        return MOZ_COLLECT_REPORT("js-main-runtime-temporary-peak",
            KIND_OTHER, UNITS_BYTES,
            JSMainRuntimeTemporaryPeakDistinguishedAmount(),
            "Peak transient data size in the main JSRuntime (the current size "
            "of which is reported as "
            "'explicit/js-non-window/runtime/temporary').");
    }
};

NS_IMPL_ISUPPORTS(JSMainRuntimeTemporaryPeakReporter, nsIMemoryReporter)

// The REPORT* macros do an unconditional report.  The ZCREPORT* macros are for
// compartments and zones; they aggregate any entries smaller than
// SUNDRIES_THRESHOLD into the "sundries/gc-heap" and "sundries/malloc-heap"
// entries for the compartment.

#define SUNDRIES_THRESHOLD js::MemoryReportingSundriesThreshold()

#define REPORT(_path, _kind, _units, _amount, _desc)                          \
    do {                                                                      \
        nsresult rv;                                                          \
        rv = cb->Callback(EmptyCString(), _path,                              \
                          nsIMemoryReporter::_kind,                           \
                          nsIMemoryReporter::_units,                          \
                          _amount,                                            \
                          NS_LITERAL_CSTRING(_desc),                          \
                          closure);                                           \
        NS_ENSURE_SUCCESS(rv, rv);                                            \
    } while (0)

#define REPORT_BYTES(_path, _kind, _amount, _desc)                            \
    REPORT(_path, _kind, UNITS_BYTES, _amount, _desc);

#define REPORT_GC_BYTES(_path, _amount, _desc)                                \
    do {                                                                      \
        size_t amount = _amount;  /* evaluate _amount only once */            \
        nsresult rv;                                                          \
        rv = cb->Callback(EmptyCString(), _path,                              \
                          nsIMemoryReporter::KIND_NONHEAP,                    \
                          nsIMemoryReporter::UNITS_BYTES, amount,             \
                          NS_LITERAL_CSTRING(_desc), closure);                \
        NS_ENSURE_SUCCESS(rv, rv);                                            \
        gcTotal += amount;                                                    \
    } while (0)

// Report compartment/zone non-GC (KIND_HEAP) bytes.
#define ZCREPORT_BYTES(_path, _amount, _desc)                                 \
    do {                                                                      \
        /* Assign _descLiteral plus "" into a char* to prove that it's */     \
        /* actually a literal. */                                             \
        size_t amount = _amount;  /* evaluate _amount only once */            \
        if (amount >= SUNDRIES_THRESHOLD) {                                   \
            nsresult rv;                                                      \
            rv = cb->Callback(EmptyCString(), _path,                          \
                              nsIMemoryReporter::KIND_HEAP,                   \
                              nsIMemoryReporter::UNITS_BYTES, amount,         \
                              NS_LITERAL_CSTRING(_desc), closure);            \
            NS_ENSURE_SUCCESS(rv, rv);                                        \
        } else {                                                              \
            sundriesMallocHeap += amount;                                     \
        }                                                                     \
    } while (0)

// Report compartment/zone GC bytes.
#define ZCREPORT_GC_BYTES(_path, _amount, _desc)                              \
    do {                                                                      \
        size_t amount = _amount;  /* evaluate _amount only once */            \
        if (amount >= SUNDRIES_THRESHOLD) {                                   \
            nsresult rv;                                                      \
            rv = cb->Callback(EmptyCString(), _path,                          \
                              nsIMemoryReporter::KIND_NONHEAP,                \
                              nsIMemoryReporter::UNITS_BYTES, amount,         \
                              NS_LITERAL_CSTRING(_desc), closure);            \
            NS_ENSURE_SUCCESS(rv, rv);                                        \
            gcTotal += amount;                                                \
        } else {                                                              \
            sundriesGCHeap += amount;                                         \
        }                                                                     \
    } while (0)

// Report runtime bytes.
#define RREPORT_BYTES(_path, _kind, _amount, _desc)                           \
    do {                                                                      \
        size_t amount = _amount;  /* evaluate _amount only once */            \
        nsresult rv;                                                          \
        rv = cb->Callback(EmptyCString(), _path,                              \
                          nsIMemoryReporter::_kind,                           \
                          nsIMemoryReporter::UNITS_BYTES, amount,             \
                          NS_LITERAL_CSTRING(_desc), closure);                \
        NS_ENSURE_SUCCESS(rv, rv);                                            \
        rtTotal += amount;                                                    \
    } while (0)

MOZ_DEFINE_MALLOC_SIZE_OF(JSMallocSizeOf)

namespace xpc {

static nsresult
ReportZoneStats(const JS::ZoneStats &zStats,
                const xpc::ZoneStatsExtras &extras,
                nsIMemoryReporterCallback *cb,
                nsISupports *closure, size_t *gcTotalOut = nullptr)
{
    const nsAutoCString& pathPrefix = extras.pathPrefix;
    size_t gcTotal = 0, sundriesGCHeap = 0, sundriesMallocHeap = 0;

    MOZ_ASSERT(!gcTotalOut == zStats.isTotals);

    ZCREPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("gc-heap-arena-admin"),
        zStats.gcHeapArenaAdmin,
        "Bookkeeping information and alignment padding within GC arenas.");

    ZCREPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("unused-gc-things"),
        zStats.unusedGCThings,
        "Empty GC thing cells within non-empty arenas.");

    ZCREPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("lazy-scripts/gc-heap"),
        zStats.lazyScriptsGCHeap,
        "Scripts that haven't executed yet.");

    ZCREPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("lazy-scripts/malloc-heap"),
        zStats.lazyScriptsMallocHeap,
        "Lazy script tables containing free variables or inner functions.");

    ZCREPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("jit-codes-gc-heap"),
        zStats.jitCodesGCHeap,
        "References to executable code pools used by the JITs.");

    ZCREPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("type-objects/gc-heap"),
        zStats.typeObjectsGCHeap,
        "Type inference information about objects.");

    ZCREPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("type-objects/malloc-heap"),
        zStats.typeObjectsMallocHeap,
        "Type object addenda.");

    ZCREPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("type-pool"),
        zStats.typePool,
        "Type sets and related data.");

    ZCREPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("baseline/optimized-stubs"),
        zStats.baselineStubsOptimized,
        "The Baseline JIT's optimized IC stubs (excluding code).");

    size_t stringsNotableAboutMemoryGCHeap = 0;
    size_t stringsNotableAboutMemoryMallocHeap = 0;

    #define MAYBE_INLINE \
        "The characters may be inline or on the malloc heap."
    #define MAYBE_OVERALLOCATED \
        "Sometimes over-allocated to simplify string concatenation."

    for (size_t i = 0; i < zStats.notableStrings.length(); i++) {
        const JS::NotableStringInfo& info = zStats.notableStrings[i];

        MOZ_ASSERT(!zStats.isTotals);

        nsDependentCString notableString(info.buffer);

        // Viewing about:memory generates many notable strings which contain
        // "string(length=".  If we report these as notable, then we'll create
        // even more notable strings the next time we open about:memory (unless
        // there's a GC in the meantime), and so on ad infinitum.
        //
        // To avoid cluttering up about:memory like this, we stick notable
        // strings which contain "string(length=" into their own bucket.
#       define STRING_LENGTH "string(length="
        if (FindInReadable(NS_LITERAL_CSTRING(STRING_LENGTH), notableString)) {
            stringsNotableAboutMemoryGCHeap += info.gcHeap;
            stringsNotableAboutMemoryMallocHeap += info.mallocHeap;
            continue;
        }

        // Escape / to \ before we put notableString into the memory reporter
        // path, because we don't want any forward slashes in the string to
        // count as path separators.
        nsCString escapedString(notableString);
        escapedString.ReplaceSubstring("/", "\\");

        bool truncated = notableString.Length() < info.length;

        nsCString path = pathPrefix +
            nsPrintfCString("strings/" STRING_LENGTH "%d, copies=%d, \"%s\"%s)/",
                            info.length, info.numCopies, escapedString.get(),
                            truncated ? " (truncated)" : "");

        if (info.gcHeap > 0) {
            REPORT_GC_BYTES(path + NS_LITERAL_CSTRING("gc-heap"),
                info.gcHeap,
                "Strings. " MAYBE_INLINE);
        }

        if (info.mallocHeap > 0) {
            REPORT_BYTES(path + NS_LITERAL_CSTRING("malloc-heap"),
                KIND_HEAP, info.mallocHeap,
                "Non-inline string characters. " MAYBE_OVERALLOCATED);
        }
    }

    nsCString nonNotablePath = pathPrefix;
    nonNotablePath += zStats.isTotals
                    ? NS_LITERAL_CSTRING("strings/")
                    : NS_LITERAL_CSTRING("strings/string(<non-notable strings>)/");

    if (zStats.stringInfo.gcHeap > 0) {
        REPORT_GC_BYTES(nonNotablePath + NS_LITERAL_CSTRING("gc-heap"),
            zStats.stringInfo.gcHeap,
            "Strings. " MAYBE_INLINE);
    }

    if (zStats.stringInfo.mallocHeap > 0) {
        REPORT_BYTES(nonNotablePath + NS_LITERAL_CSTRING("malloc-heap"),
            KIND_HEAP, zStats.stringInfo.mallocHeap,
            "Non-inline string characters. " MAYBE_OVERALLOCATED);
    }

    if (stringsNotableAboutMemoryGCHeap > 0) {
        MOZ_ASSERT(!zStats.isTotals);
        REPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("strings/string(<about-memory>)/gc-heap"),
            stringsNotableAboutMemoryGCHeap,
            "Strings that contain the characters '" STRING_LENGTH "', which "
            "are probably from about:memory itself." MAYBE_INLINE
            " We filter them out rather than display them, because displaying "
            "them would create even more such strings every time about:memory "
            "is refreshed.");
    }

    if (stringsNotableAboutMemoryMallocHeap > 0) {
        MOZ_ASSERT(!zStats.isTotals);
        REPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("strings/string(<about-memory>)/malloc-heap"),
            KIND_HEAP, stringsNotableAboutMemoryMallocHeap,
            "Non-inline string characters of strings that contain the "
            "characters '" STRING_LENGTH "', which are probably from "
            "about:memory itself. " MAYBE_OVERALLOCATED
            " We filter them out rather than display them, because displaying "
            "them would create even more such strings every time about:memory "
            "is refreshed.");
    }

    if (sundriesGCHeap > 0) {
        // We deliberately don't use ZCREPORT_GC_BYTES here.
        REPORT_GC_BYTES(pathPrefix + NS_LITERAL_CSTRING("sundries/gc-heap"),
            sundriesGCHeap,
            "The sum of all 'gc-heap' measurements that are too small to be "
            "worth showing individually.");
    }

    if (sundriesMallocHeap > 0) {
        // We deliberately don't use ZCREPORT_BYTES here.
        REPORT_BYTES(pathPrefix + NS_LITERAL_CSTRING("sundries/malloc-heap"),
            KIND_HEAP, sundriesMallocHeap,
            "The sum of all 'malloc-heap' measurements that are too small to "
            "be worth showing individually.");
    }

    if (gcTotalOut)
        *gcTotalOut += gcTotal;

    return NS_OK;

#   undef STRING_LENGTH
}

static nsresult
ReportCompartmentStats(const JS::CompartmentStats &cStats,
                       const xpc::CompartmentStatsExtras &extras,
                       amIAddonManager *addonManager,
                       nsIMemoryReporterCallback *cb,
                       nsISupports *closure, size_t *gcTotalOut = nullptr)
{
    static const nsDependentCString addonPrefix("explicit/add-ons/");

    size_t gcTotal = 0, sundriesGCHeap = 0, sundriesMallocHeap = 0;
    nsAutoCString cJSPathPrefix = extras.jsPathPrefix;
    nsAutoCString cDOMPathPrefix = extras.domPathPrefix;

    // Only attempt to prefix if we got a location and the path wasn't already
    // prefixed.
    if (extras.location && addonManager &&
        cJSPathPrefix.Find(addonPrefix, false, 0, 0) != 0) {
        nsAutoCString addonId;
        bool ok;
        if (NS_SUCCEEDED(addonManager->MapURIToAddonID(extras.location,
                                                        addonId, &ok))
            && ok) {
            // Insert the add-on id as "add-ons/@id@/" after "explicit/" to
            // aggregate add-on compartments.
            static const size_t explicitLength = strlen("explicit/");
            addonId.Insert(NS_LITERAL_CSTRING("add-ons/"), 0);
            addonId += "/";
            cJSPathPrefix.Insert(addonId, explicitLength);
            cDOMPathPrefix.Insert(addonId, explicitLength);
        }
    }

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/gc-heap/ordinary"),
        cStats.objectsGCHeapOrdinary,
        "Ordinary objects, i.e. not otherwise distinguished by memory "
        "reporters.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/gc-heap/function"),
        cStats.objectsGCHeapFunction,
        "Function objects.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/gc-heap/dense-array"),
        cStats.objectsGCHeapDenseArray,
        "Dense array objects.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/gc-heap/slow-array"),
        cStats.objectsGCHeapSlowArray,
        "Slow array objects.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/gc-heap/cross-compartment-wrapper"),
        cStats.objectsGCHeapCrossCompartmentWrapper,
        "Cross-compartment wrapper objects.");

    // Note that we use cDOMPathPrefix here.  This is because we measure orphan
    // DOM nodes in the JS reporter, but we want to report them in a "dom"
    // sub-tree rather than a "js" sub-tree.
    ZCREPORT_BYTES(cDOMPathPrefix + NS_LITERAL_CSTRING("orphan-nodes"),
        cStats.objectsPrivate,
        "Orphan DOM nodes, i.e. those that are only reachable from JavaScript "
        "objects.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/gc-heap/tree/global-parented"),
        cStats.shapesGCHeapTreeGlobalParented,
        "Shapes that (a) are in a property tree, and (b) represent an object "
        "whose parent is the global object.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/gc-heap/tree/non-global-parented"),
        cStats.shapesGCHeapTreeNonGlobalParented,
        "Shapes that (a) are in a property tree, and (b) represent an object "
        "whose parent is not the global object.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/gc-heap/dict"),
        cStats.shapesGCHeapDict,
        "Shapes that are in dictionary mode.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/gc-heap/base"),
        cStats.shapesGCHeapBase,
        "Base shapes, which collate data common to many shapes.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/malloc-heap/tree-tables"),
        cStats.shapesMallocHeapTreeTables,
        "Property tables belonging to shapes that are in a property tree.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/malloc-heap/dict-tables"),
        cStats.shapesMallocHeapDictTables,
        "Property tables that belong to shapes that are in dictionary mode.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/malloc-heap/tree-shape-kids"),
        cStats.shapesMallocHeapTreeShapeKids,
        "Kid hashes that belong to shapes that are in a property tree.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("shapes/malloc-heap/compartment-tables"),
        cStats.shapesMallocHeapCompartmentTables,
        "Compartment-wide tables storing shape information used during object "
        "construction.");

    ZCREPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("scripts/gc-heap"),
        cStats.scriptsGCHeap,
        "JSScript instances. There is one per user-defined function in a "
        "script, and one for the top-level code in a script.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("scripts/malloc-heap/data"),
        cStats.scriptsMallocHeapData,
        "Various variable-length tables in JSScripts.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("baseline/data"),
        cStats.baselineData,
        "The Baseline JIT's compilation data (BaselineScripts).");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("baseline/fallback-stubs"),
        cStats.baselineStubsFallback,
        "The Baseline JIT's fallback IC stubs (excluding code).");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("ion-data"),
        cStats.ionData,
        "The IonMonkey JIT's compilation data (IonScripts).");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("type-inference/type-scripts"),
        cStats.typeInferenceTypeScripts,
        "Type sets associated with scripts.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("type-inference/allocation-site-tables"),
        cStats.typeInferenceAllocationSiteTables,
        "Tables of type objects associated with allocation sites.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("type-inference/array-type-tables"),
        cStats.typeInferenceArrayTypeTables,
        "Tables of type objects associated with array literals.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("type-inference/object-type-tables"),
        cStats.typeInferenceObjectTypeTables,
        "Tables of type objects associated with object literals.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("compartment-object"),
        cStats.compartmentObject,
        "The JSCompartment object itself.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("cross-compartment-wrapper-table"),
        cStats.crossCompartmentWrappersTable,
        "The cross-compartment wrapper table.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("regexp-compartment"),
        cStats.regexpCompartment,
        "The regexp compartment and regexp data.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("debuggees-set"),
        cStats.debuggeesSet,
        "The debuggees set.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/slots"),
        cStats.objectsExtra.mallocHeapSlots,
        "Non-fixed object slot arrays, which represent object properties.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/elements/non-asm.js"),
        cStats.objectsExtra.mallocHeapElementsNonAsmJS,
        "Non-asm.js indexed elements.");

    // asm.js arrays are heap-allocated on some platforms and
    // non-heap-allocated on others.  We never put them under sundries,
    // because (a) in practice they're almost always larger than the sundries
    // threshold, and (b) we'd need a third category of sundries ("non-heap"),
    // which would be a pain.
    size_t mallocHeapElementsAsmJS = cStats.objectsExtra.mallocHeapElementsAsmJS;
    size_t nonHeapElementsAsmJS    = cStats.objectsExtra.nonHeapElementsAsmJS;
    MOZ_ASSERT(mallocHeapElementsAsmJS == 0 || nonHeapElementsAsmJS == 0);
    if (mallocHeapElementsAsmJS > 0) {
        REPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/elements/asm.js"),
            KIND_HEAP, mallocHeapElementsAsmJS,
            "asm.js array buffer elements on the malloc heap.");
    }
    if (nonHeapElementsAsmJS > 0) {
        REPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/non-heap/elements/asm.js"),
            KIND_NONHEAP, nonHeapElementsAsmJS,
            "asm.js array buffer elements outside both the malloc heap and "
            "the GC heap.");
    }

    if (cStats.objectsExtra.nonHeapElementsMapped > 0) {
        REPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/non-heap/elements/mapped"),
            KIND_NONHEAP, cStats.objectsExtra.nonHeapElementsMapped,
            "Memory-mapped array buffer elements.");
    }

    REPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/non-heap/code/asm.js"),
        KIND_NONHEAP, cStats.objectsExtra.nonHeapCodeAsmJS,
        "AOT-compiled asm.js code.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/asm.js-module-data"),
        cStats.objectsExtra.mallocHeapAsmJSModuleData,
        "asm.js module data.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/arguments-data"),
        cStats.objectsExtra.mallocHeapArgumentsData,
        "Data belonging to Arguments objects.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/regexp-statics"),
        cStats.objectsExtra.mallocHeapRegExpStatics,
        "Data belonging to the RegExpStatics object.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/property-iterator-data"),
        cStats.objectsExtra.mallocHeapPropertyIteratorData,
        "Data belonging to property iterator objects.");

    ZCREPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("objects/malloc-heap/ctypes-data"),
        cStats.objectsExtra.mallocHeapCtypesData,
        "Data belonging to ctypes objects.");

    if (sundriesGCHeap > 0) {
        // We deliberately don't use ZCREPORT_GC_BYTES here.
        REPORT_GC_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("sundries/gc-heap"),
            sundriesGCHeap,
            "The sum of all 'gc-heap' measurements that are too small to be "
            "worth showing individually.");
    }

    if (sundriesMallocHeap > 0) {
        // We deliberately don't use ZCREPORT_BYTES here.
        REPORT_BYTES(cJSPathPrefix + NS_LITERAL_CSTRING("sundries/malloc-heap"),
            KIND_HEAP, sundriesMallocHeap,
            "The sum of all 'malloc-heap' measurements that are too small to "
            "be worth showing individually.");
    }

    if (gcTotalOut)
        *gcTotalOut += gcTotal;

    return NS_OK;
}

static nsresult
ReportScriptSourceStats(const ScriptSourceInfo &scriptSourceInfo,
                        const nsACString &path,
                        nsIHandleReportCallback *cb, nsISupports *closure,
                        size_t &rtTotal)
{
    if (scriptSourceInfo.compressed > 0) {
        RREPORT_BYTES(path + NS_LITERAL_CSTRING("compressed"),
            KIND_HEAP, scriptSourceInfo.compressed,
            "Compressed JavaScript source code.");
    }

    if (scriptSourceInfo.uncompressed > 0) {
        RREPORT_BYTES(path + NS_LITERAL_CSTRING("uncompressed"),
            KIND_HEAP, scriptSourceInfo.uncompressed,
            "Uncompressed JavaScript source code.");
    }

    if (scriptSourceInfo.misc > 0) {
        RREPORT_BYTES(path + NS_LITERAL_CSTRING("misc"),
            KIND_HEAP, scriptSourceInfo.misc,
            "Miscellaneous data relating to JavaScript source code.");
    }

    return NS_OK;
}

static nsresult
ReportJSRuntimeExplicitTreeStats(const JS::RuntimeStats &rtStats,
                                 const nsACString &rtPath,
                                 amIAddonManager* addonManager,
                                 nsIMemoryReporterCallback *cb,
                                 nsISupports *closure, size_t *rtTotalOut)
{
    nsresult rv;

    size_t gcTotal = 0;

    for (size_t i = 0; i < rtStats.zoneStatsVector.length(); i++) {
        const JS::ZoneStats &zStats = rtStats.zoneStatsVector[i];
        const xpc::ZoneStatsExtras *extras =
          static_cast<const xpc::ZoneStatsExtras*>(zStats.extra);
        rv = ReportZoneStats(zStats, *extras, cb, closure, &gcTotal);
        NS_ENSURE_SUCCESS(rv, rv);
    }

    for (size_t i = 0; i < rtStats.compartmentStatsVector.length(); i++) {
        JS::CompartmentStats cStats = rtStats.compartmentStatsVector[i];
        const xpc::CompartmentStatsExtras *extras =
            static_cast<const xpc::CompartmentStatsExtras*>(cStats.extra);
        rv = ReportCompartmentStats(cStats, *extras, addonManager, cb, closure,
                                    &gcTotal);
        NS_ENSURE_SUCCESS(rv, rv);
    }

    // Report the rtStats.runtime numbers under "runtime/", and compute their
    // total for later.

    size_t rtTotal = 0;

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/runtime-object"),
        KIND_HEAP, rtStats.runtime.object,
        "The JSRuntime object.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/atoms-table"),
        KIND_HEAP, rtStats.runtime.atomsTable,
        "The atoms table.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/contexts"),
        KIND_HEAP, rtStats.runtime.contexts,
        "JSContext objects and structures that belong to them.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/dtoa"),
        KIND_HEAP, rtStats.runtime.dtoa,
        "The DtoaState object, which is used for converting strings to "
        "numbers and vice versa.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/temporary"),
        KIND_HEAP, rtStats.runtime.temporary,
        "Transient data (mostly parse nodes) held by the JSRuntime during "
        "compilation.");

#ifdef JS_YARR
    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/regexp-data"),
        KIND_NONHEAP, rtStats.runtime.regexpData,
        "Regexp JIT data.");
#endif

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/interpreter-stack"),
        KIND_HEAP, rtStats.runtime.interpreterStack,
        "JS interpreter frames.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/math-cache"),
        KIND_HEAP, rtStats.runtime.mathCache,
        "The math cache.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/source-data-cache"),
        KIND_HEAP, rtStats.runtime.sourceDataCache,
        "The source data cache, which holds decompressed script source code.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/script-data"),
        KIND_HEAP, rtStats.runtime.scriptData,
        "The table holding script data shared in the runtime.");

    nsCString nonNotablePath =
        rtPath + nsPrintfCString("runtime/script-sources/source(scripts=%d, <non-notable files>)/",
                                 rtStats.runtime.scriptSourceInfo.numScripts);

    rv = ReportScriptSourceStats(rtStats.runtime.scriptSourceInfo,
                                 nonNotablePath, cb, closure, rtTotal);
    NS_ENSURE_SUCCESS(rv, rv);

    for (size_t i = 0; i < rtStats.runtime.notableScriptSources.length(); i++) {
        const JS::NotableScriptSourceInfo& scriptSourceInfo =
            rtStats.runtime.notableScriptSources[i];

        // Escape / to \ before we put the filename into the memory reporter
        // path, because we don't want any forward slashes in the string to
        // count as path separators. Consumers of memory reporters (e.g.
        // about:memory) will convert them back to / after doing path
        // splitting.
        nsDependentCString filename(scriptSourceInfo.filename_);
        nsCString escapedFilename(filename);
        escapedFilename.ReplaceSubstring("/", "\\");

        nsCString notablePath = rtPath +
            nsPrintfCString("runtime/script-sources/source(scripts=%d, %s)/",
                            scriptSourceInfo.numScripts, escapedFilename.get());

        rv = ReportScriptSourceStats(scriptSourceInfo, notablePath,
                                     cb, closure, rtTotal);
        NS_ENSURE_SUCCESS(rv, rv);
    }

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/code/ion"),
        KIND_NONHEAP, rtStats.runtime.code.ion,
        "Code generated by the IonMonkey JIT.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/code/baseline"),
        KIND_NONHEAP, rtStats.runtime.code.baseline,
        "Code generated by the Baseline JIT.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/code/regexp"),
        KIND_NONHEAP, rtStats.runtime.code.regexp,
        "Code generated by the regexp JIT.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/code/other"),
        KIND_NONHEAP, rtStats.runtime.code.other,
        "Code generated by the JITs for wrappers and trampolines.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/code/unused"),
        KIND_NONHEAP, rtStats.runtime.code.unused,
        "Memory allocated by one of the JITs to hold code, but which is "
        "currently unused.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/marker"),
        KIND_HEAP, rtStats.runtime.gc.marker,
        "The GC mark stack and gray roots.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/nursery-committed"),
        KIND_NONHEAP, rtStats.runtime.gc.nurseryCommitted,
        "Memory being used by the GC's nursery.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/nursery-huge-slots"),
        KIND_NONHEAP, rtStats.runtime.gc.nurseryHugeSlots,
        "Out-of-line slots and elements belonging to objects in the "
        "nursery.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/vals"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferVals,
        "Values in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/cells"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferCells,
        "Cells in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/slots"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferSlots,
        "Slots in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/whole-cells"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferWholeCells,
        "Whole cells in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/reloc-vals"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferRelocVals,
        "Relocatable values in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/reloc-cells"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferRelocCells,
        "Relocatable cells in the store buffer.");

    RREPORT_BYTES(rtPath + NS_LITERAL_CSTRING("runtime/gc/store-buffer/generics"),
        KIND_HEAP, rtStats.runtime.gc.storeBufferGenerics,
        "Generic things in the store buffer.");

    if (rtTotalOut)
        *rtTotalOut = rtTotal;

    // Report GC numbers that don't belong to a compartment.

    // We don't want to report decommitted memory in "explicit", so we just
    // change the leading "explicit/" to "decommitted/".
    nsCString rtPath2(rtPath);
    rtPath2.Replace(0, strlen("explicit"), NS_LITERAL_CSTRING("decommitted"));
    REPORT_GC_BYTES(rtPath2 + NS_LITERAL_CSTRING("gc-heap/decommitted-arenas"),
        rtStats.gcHeapDecommittedArenas,
        "GC arenas in non-empty chunks that is decommitted, i.e. it takes up "
        "address space but no physical memory or swap space.");

    REPORT_BYTES(rtPath2 + NS_LITERAL_CSTRING("runtime/gc/nursery-decommitted"),
        KIND_NONHEAP, rtStats.runtime.gc.nurseryDecommitted,
        "Memory allocated to the GC's nursery this is decommitted, i.e. it takes up "
        "address space but no physical memory or swap space.");

    REPORT_GC_BYTES(rtPath + NS_LITERAL_CSTRING("gc-heap/unused-chunks"),
        rtStats.gcHeapUnusedChunks,
        "Empty GC chunks which will soon be released unless claimed for new "
        "allocations.");

    REPORT_GC_BYTES(rtPath + NS_LITERAL_CSTRING("gc-heap/unused-arenas"),
        rtStats.gcHeapUnusedArenas,
        "Empty GC arenas within non-empty chunks.");

    REPORT_GC_BYTES(rtPath + NS_LITERAL_CSTRING("gc-heap/chunk-admin"),
        rtStats.gcHeapChunkAdmin,
        "Bookkeeping information within GC chunks.");

    // gcTotal is the sum of everything we've reported for the GC heap.  It
    // should equal rtStats.gcHeapChunkTotal.
    MOZ_ASSERT(gcTotal == rtStats.gcHeapChunkTotal);

    return NS_OK;
}

nsresult
ReportJSRuntimeExplicitTreeStats(const JS::RuntimeStats &rtStats,
                                 const nsACString &rtPath,
                                 nsIMemoryReporterCallback *cb,
                                 nsISupports *closure, size_t *rtTotalOut)
{
    nsCOMPtr<amIAddonManager> am;
    if (XRE_GetProcessType() == GeckoProcessType_Default) {
        // Only try to access the service from the main process.
        am = do_GetService("@mozilla.org/addons/integration;1");
    }
    return ReportJSRuntimeExplicitTreeStats(rtStats, rtPath, am.get(), cb,
                                            closure, rtTotalOut);
}


} // namespace xpc

class JSMainRuntimeCompartmentsReporter MOZ_FINAL : public nsIMemoryReporter
{
  public:
    NS_DECL_ISUPPORTS

    typedef js::Vector<nsCString, 0, js::SystemAllocPolicy> Paths;

    static void CompartmentCallback(JSRuntime *rt, void* data, JSCompartment *c) {
        // silently ignore OOM errors
        Paths *paths = static_cast<Paths *>(data);
        nsCString path;
        GetCompartmentName(c, path, true);
        path.Insert(js::IsSystemCompartment(c)
                    ? NS_LITERAL_CSTRING("js-main-runtime-compartments/system/")
                    : NS_LITERAL_CSTRING("js-main-runtime-compartments/user/"),
                    0);
        paths->append(path);
    }

    NS_IMETHOD CollectReports(nsIMemoryReporterCallback *cb,
                              nsISupports *closure)
    {
        // First we collect the compartment paths.  Then we report them.  Doing
        // the two steps interleaved is a bad idea, because calling |cb|
        // from within CompartmentCallback() leads to all manner of assertions.

        // Collect.

        Paths paths;
        JS_IterateCompartments(nsXPConnect::GetRuntimeInstance()->Runtime(),
                               &paths, CompartmentCallback);

        // Report.
        for (size_t i = 0; i < paths.length(); i++)
            // These ones don't need a description, hence the "".
            REPORT(nsCString(paths[i]), KIND_OTHER, UNITS_COUNT, 1,
                "A live compartment in the main JSRuntime.");

        return NS_OK;
    }
};

NS_IMPL_ISUPPORTS(JSMainRuntimeCompartmentsReporter, nsIMemoryReporter)

MOZ_DEFINE_MALLOC_SIZE_OF(OrphanMallocSizeOf)

namespace xpc {

static size_t
SizeOfTreeIncludingThis(nsINode *tree)
{
    size_t n = tree->SizeOfIncludingThis(OrphanMallocSizeOf);
    for (nsIContent* child = tree->GetFirstChild(); child; child = child->GetNextNode(tree))
        n += child->SizeOfIncludingThis(OrphanMallocSizeOf);

    return n;
}

class OrphanReporter : public JS::ObjectPrivateVisitor
{
  public:
    OrphanReporter(GetISupportsFun aGetISupports)
      : JS::ObjectPrivateVisitor(aGetISupports)
    {
    }

    virtual size_t sizeOfIncludingThis(nsISupports *aSupports) MOZ_OVERRIDE {
        size_t n = 0;
        nsCOMPtr<nsINode> node = do_QueryInterface(aSupports);
        // https://bugzilla.mozilla.org/show_bug.cgi?id=773533#c11 explains
        // that we have to skip XBL elements because they violate certain
        // assumptions.  Yuk.
        if (node && !node->IsInDoc() &&
            !(node->IsElement() && node->AsElement()->IsInNamespace(kNameSpaceID_XBL)))
        {
            // This is an orphan node.  If we haven't already handled the
            // sub-tree that this node belongs to, measure the sub-tree's size
            // and then record its root so we don't measure it again.
            nsCOMPtr<nsINode> orphanTree = node->SubtreeRoot();
            if (!mAlreadyMeasuredOrphanTrees.Contains(orphanTree)) {
                n += SizeOfTreeIncludingThis(orphanTree);
                mAlreadyMeasuredOrphanTrees.PutEntry(orphanTree);
            }
        }
        return n;
    }

  private:
    nsTHashtable <nsISupportsHashKey> mAlreadyMeasuredOrphanTrees;
};

#ifdef DEBUG
static bool
StartsWithExplicit(nsACString& s)
{
    const char* e = "explicit/";
    return Substring(s, 0, strlen(e)).Equals(e);
}
#endif

class XPCJSRuntimeStats : public JS::RuntimeStats
{
    WindowPaths *mWindowPaths;
    WindowPaths *mTopWindowPaths;
    bool mGetLocations;

  public:
    XPCJSRuntimeStats(WindowPaths *windowPaths, WindowPaths *topWindowPaths,
                      bool getLocations)
      : JS::RuntimeStats(JSMallocSizeOf),
        mWindowPaths(windowPaths),
        mTopWindowPaths(topWindowPaths),
        mGetLocations(getLocations)
    {}

    ~XPCJSRuntimeStats() {
        for (size_t i = 0; i != compartmentStatsVector.length(); ++i)
            delete static_cast<xpc::CompartmentStatsExtras*>(compartmentStatsVector[i].extra);


        for (size_t i = 0; i != zoneStatsVector.length(); ++i)
            delete static_cast<xpc::ZoneStatsExtras*>(zoneStatsVector[i].extra);
    }

    virtual void initExtraZoneStats(JS::Zone *zone, JS::ZoneStats *zStats) MOZ_OVERRIDE {
        // Get the compartment's global.
        nsXPConnect *xpc = nsXPConnect::XPConnect();
        AutoSafeJSContext cx;
        JSCompartment *comp = js::GetAnyCompartmentInZone(zone);
        xpc::ZoneStatsExtras *extras = new xpc::ZoneStatsExtras;
        extras->pathPrefix.AssignLiteral("explicit/js-non-window/zones/");
        RootedObject global(cx, JS_GetGlobalForCompartmentOrNull(cx, comp));
        if (global) {
            // Need to enter the compartment, otherwise GetNativeOfWrapper()
            // might crash.
            JSAutoCompartment ac(cx, global);
            nsISupports *native = xpc->GetNativeOfWrapper(cx, global);
            if (nsCOMPtr<nsPIDOMWindow> piwindow = do_QueryInterface(native)) {
                // The global is a |window| object.  Use the path prefix that
                // we should have already created for it.
                if (mTopWindowPaths->Get(piwindow->WindowID(),
                                         &extras->pathPrefix))
                    extras->pathPrefix.AppendLiteral("/js-");
            }
        }

        extras->pathPrefix += nsPrintfCString("zone(0x%p)/", (void *)zone);

        MOZ_ASSERT(StartsWithExplicit(extras->pathPrefix));

        zStats->extra = extras;
    }

    virtual void initExtraCompartmentStats(JSCompartment *c,
                                           JS::CompartmentStats *cstats) MOZ_OVERRIDE
    {
        xpc::CompartmentStatsExtras *extras = new xpc::CompartmentStatsExtras;
        nsCString cName;
        GetCompartmentName(c, cName, true);
        if (mGetLocations) {
            CompartmentPrivate *cp = GetCompartmentPrivate(c);
            if (cp)
              cp->GetLocationURI(CompartmentPrivate::LocationHintAddon,
                                 getter_AddRefs(extras->location));
            // Note: cannot use amIAddonManager implementation at this point,
            // as it is a JS service and the JS heap is currently not idle.
            // Otherwise, we could have computed the add-on id at this point.
        }

        // Get the compartment's global.
        nsXPConnect *xpc = nsXPConnect::XPConnect();
        AutoSafeJSContext cx;
        bool needZone = true;
        RootedObject global(cx, JS_GetGlobalForCompartmentOrNull(cx, c));
        if (global) {
            // Need to enter the compartment, otherwise GetNativeOfWrapper()
            // might crash.
            JSAutoCompartment ac(cx, global);
            nsISupports *native = xpc->GetNativeOfWrapper(cx, global);
            if (nsCOMPtr<nsPIDOMWindow> piwindow = do_QueryInterface(native)) {
                // The global is a |window| object.  Use the path prefix that
                // we should have already created for it.
                if (mWindowPaths->Get(piwindow->WindowID(),
                                      &extras->jsPathPrefix)) {
                    extras->domPathPrefix.Assign(extras->jsPathPrefix);
                    extras->domPathPrefix.AppendLiteral("/dom/");
                    extras->jsPathPrefix.AppendLiteral("/js-");
                    needZone = false;
                } else {
                    extras->jsPathPrefix.AssignLiteral("explicit/js-non-window/zones/");
                    extras->domPathPrefix.AssignLiteral("explicit/dom/unknown-window-global?!/");
                }
            } else {
                extras->jsPathPrefix.AssignLiteral("explicit/js-non-window/zones/");
                extras->domPathPrefix.AssignLiteral("explicit/dom/non-window-global?!/");
            }
        } else {
            extras->jsPathPrefix.AssignLiteral("explicit/js-non-window/zones/");
            extras->domPathPrefix.AssignLiteral("explicit/dom/no-global?!/");
        }

        if (needZone)
            extras->jsPathPrefix += nsPrintfCString("zone(0x%p)/", (void *)js::GetCompartmentZone(c));

        extras->jsPathPrefix += NS_LITERAL_CSTRING("compartment(") + cName + NS_LITERAL_CSTRING(")/");

        // extras->jsPathPrefix is used for almost all the compartment-specific
        // reports. At this point it has the form
        // "<something>compartment(<cname>)/".
        //
        // extras->domPathPrefix is used for DOM orphan nodes, which are
        // counted by the JS reporter but reported as part of the DOM
        // measurements. At this point it has the form "<something>/dom/" if
        // this compartment belongs to an nsGlobalWindow, and
        // "explicit/dom/<something>?!/" otherwise (in which case it shouldn't
        // be used, because non-nsGlobalWindow compartments shouldn't have
        // orphan DOM nodes).

        MOZ_ASSERT(StartsWithExplicit(extras->jsPathPrefix));
        MOZ_ASSERT(StartsWithExplicit(extras->domPathPrefix));

        cstats->extra = extras;
    }
};

nsresult
JSReporter::CollectReports(WindowPaths *windowPaths,
                           WindowPaths *topWindowPaths,
                           nsIMemoryReporterCallback *cb,
                           nsISupports *closure)
{
    XPCJSRuntime *xpcrt = nsXPConnect::GetRuntimeInstance();

    // In the first step we get all the stats and stash them in a local
    // data structure.  In the second step we pass all the stashed stats to
    // the callback.  Separating these steps is important because the
    // callback may be a JS function, and executing JS while getting these
    // stats seems like a bad idea.

    nsCOMPtr<amIAddonManager> addonManager;
    if (XRE_GetProcessType() == GeckoProcessType_Default) {
        // Only try to access the service from the main process.
        addonManager = do_GetService("@mozilla.org/addons/integration;1");
    }
    bool getLocations = !!addonManager;
    XPCJSRuntimeStats rtStats(windowPaths, topWindowPaths, getLocations);
    OrphanReporter orphanReporter(XPCConvert::GetISupportsFromJSObject);
    if (!JS::CollectRuntimeStats(xpcrt->Runtime(), &rtStats, &orphanReporter))
        return NS_ERROR_FAILURE;

    size_t xpconnect = xpcrt->SizeOfIncludingThis(JSMallocSizeOf);

    XPCWrappedNativeScope::ScopeSizeInfo sizeInfo(JSMallocSizeOf);
    XPCWrappedNativeScope::AddSizeOfAllScopesIncludingThis(&sizeInfo);

    mozJSComponentLoader* loader = mozJSComponentLoader::Get();
    size_t jsComponentLoaderSize = loader ? loader->SizeOfIncludingThis(JSMallocSizeOf) : 0;

    // This is the second step (see above).  First we report stuff in the
    // "explicit" tree, then we report other stuff.

    nsresult rv;
    size_t rtTotal = 0;
    rv = xpc::ReportJSRuntimeExplicitTreeStats(rtStats,
                                               NS_LITERAL_CSTRING("explicit/js-non-window/"),
                                               addonManager, cb, closure,
                                               &rtTotal);
    NS_ENSURE_SUCCESS(rv, rv);

    // Report the sums of the compartment numbers.
    xpc::CompartmentStatsExtras cExtrasTotal;
    cExtrasTotal.jsPathPrefix.AssignLiteral("js-main-runtime/compartments/");
    cExtrasTotal.domPathPrefix.AssignLiteral("window-objects/dom/");
    rv = ReportCompartmentStats(rtStats.cTotals, cExtrasTotal, addonManager,
                                cb, closure);
    NS_ENSURE_SUCCESS(rv, rv);

    xpc::ZoneStatsExtras zExtrasTotal;
    zExtrasTotal.pathPrefix.AssignLiteral("js-main-runtime/zones/");
    rv = ReportZoneStats(rtStats.zTotals, zExtrasTotal, cb, closure);
    NS_ENSURE_SUCCESS(rv, rv);

    // Report the sum of the runtime/ numbers.
    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime/runtime"),
        KIND_OTHER, rtTotal,
        "The sum of all measurements under 'explicit/js-non-window/runtime/'.");

    // Report the numbers for memory outside of compartments.

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime/gc-heap/unused-chunks"),
        KIND_OTHER, rtStats.gcHeapUnusedChunks,
        "The same as 'explicit/js-non-window/gc-heap/unused-chunks'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime/gc-heap/unused-arenas"),
        KIND_OTHER, rtStats.gcHeapUnusedArenas,
        "The same as 'explicit/js-non-window/gc-heap/unused-arenas'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime/gc-heap/chunk-admin"),
        KIND_OTHER, rtStats.gcHeapChunkAdmin,
        "The same as 'explicit/js-non-window/gc-heap/chunk-admin'.");

    // Report a breakdown of the committed GC space.

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/unused/chunks"),
        KIND_OTHER, rtStats.gcHeapUnusedChunks,
        "The same as 'explicit/js-non-window/gc-heap/unused-chunks'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/unused/arenas"),
        KIND_OTHER, rtStats.gcHeapUnusedArenas,
        "The same as 'explicit/js-non-window/gc-heap/unused-arenas'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/unused/gc-things"),
        KIND_OTHER, rtStats.zTotals.unusedGCThings,
        "The same as 'js-main-runtime/zones/unused-gc-things'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/used/chunk-admin"),
        KIND_OTHER, rtStats.gcHeapChunkAdmin,
        "The same as 'explicit/js-non-window/gc-heap/chunk-admin'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/used/arena-admin"),
        KIND_OTHER, rtStats.zTotals.gcHeapArenaAdmin,
        "The same as 'js-main-runtime/zones/gc-heap-arena-admin'.");

    REPORT_BYTES(NS_LITERAL_CSTRING("js-main-runtime-gc-heap-committed/used/gc-things"),
        KIND_OTHER, rtStats.gcHeapGCThings,
        "GC things: objects, strings, scripts, etc.");

    // Report xpconnect.

    REPORT_BYTES(NS_LITERAL_CSTRING("explicit/xpconnect/runtime"),
        KIND_HEAP, xpconnect,
        "The XPConnect runtime.");

    REPORT_BYTES(NS_LITERAL_CSTRING("explicit/xpconnect/scopes"),
        KIND_HEAP, sizeInfo.mScopeAndMapSize,
        "XPConnect scopes.");

    REPORT_BYTES(NS_LITERAL_CSTRING("explicit/xpconnect/proto-iface-cache"),
        KIND_HEAP, sizeInfo.mProtoAndIfaceCacheSize,
        "Prototype and interface binding caches.");

    REPORT_BYTES(NS_LITERAL_CSTRING("explicit/xpconnect/js-component-loader"),
        KIND_HEAP, jsComponentLoaderSize,
        "XPConnect's JS component loader.");

    return NS_OK;
}

static nsresult
JSSizeOfTab(JSObject *objArg, size_t *jsObjectsSize, size_t *jsStringsSize,
            size_t *jsPrivateSize, size_t *jsOtherSize)
{
    JSRuntime *rt = nsXPConnect::GetRuntimeInstance()->Runtime();
    JS::RootedObject obj(rt, objArg);

    TabSizes sizes;
    OrphanReporter orphanReporter(XPCConvert::GetISupportsFromJSObject);
    NS_ENSURE_TRUE(JS::AddSizeOfTab(rt, obj, moz_malloc_size_of,
                                    &orphanReporter, &sizes),
                   NS_ERROR_OUT_OF_MEMORY);

    *jsObjectsSize = sizes.objects;
    *jsStringsSize = sizes.strings;
    *jsPrivateSize = sizes.private_;
    *jsOtherSize   = sizes.other;
    return NS_OK;
}

} // namespace xpc

#ifdef MOZ_CRASHREPORTER
static bool
DiagnosticMemoryCallback(void *ptr, size_t size)
{
    return CrashReporter::RegisterAppMemory(ptr, size) == NS_OK;
}
#endif

static void
AccumulateTelemetryCallback(int id, uint32_t sample)
{
    switch (id) {
      case JS_TELEMETRY_GC_REASON:
        Telemetry::Accumulate(Telemetry::GC_REASON_2, sample);
        break;
      case JS_TELEMETRY_GC_IS_COMPARTMENTAL:
        Telemetry::Accumulate(Telemetry::GC_IS_COMPARTMENTAL, sample);
        break;
      case JS_TELEMETRY_GC_MS:
        Telemetry::Accumulate(Telemetry::GC_MS, sample);
        break;
      case JS_TELEMETRY_GC_MAX_PAUSE_MS:
        Telemetry::Accumulate(Telemetry::GC_MAX_PAUSE_MS, sample);
        break;
      case JS_TELEMETRY_GC_MARK_MS:
        Telemetry::Accumulate(Telemetry::GC_MARK_MS, sample);
        break;
      case JS_TELEMETRY_GC_SWEEP_MS:
        Telemetry::Accumulate(Telemetry::GC_SWEEP_MS, sample);
        break;
      case JS_TELEMETRY_GC_MARK_ROOTS_MS:
        Telemetry::Accumulate(Telemetry::GC_MARK_ROOTS_MS, sample);
        break;
      case JS_TELEMETRY_GC_MARK_GRAY_MS:
        Telemetry::Accumulate(Telemetry::GC_MARK_GRAY_MS, sample);
        break;
      case JS_TELEMETRY_GC_SLICE_MS:
        Telemetry::Accumulate(Telemetry::GC_SLICE_MS, sample);
        break;
      case JS_TELEMETRY_GC_MMU_50:
        Telemetry::Accumulate(Telemetry::GC_MMU_50, sample);
        break;
      case JS_TELEMETRY_GC_RESET:
        Telemetry::Accumulate(Telemetry::GC_RESET, sample);
        break;
      case JS_TELEMETRY_GC_INCREMENTAL_DISABLED:
        Telemetry::Accumulate(Telemetry::GC_INCREMENTAL_DISABLED, sample);
        break;
      case JS_TELEMETRY_GC_NON_INCREMENTAL:
        Telemetry::Accumulate(Telemetry::GC_NON_INCREMENTAL, sample);
        break;
      case JS_TELEMETRY_GC_SCC_SWEEP_TOTAL_MS:
        Telemetry::Accumulate(Telemetry::GC_SCC_SWEEP_TOTAL_MS, sample);
        break;
      case JS_TELEMETRY_GC_SCC_SWEEP_MAX_PAUSE_MS:
        Telemetry::Accumulate(Telemetry::GC_SCC_SWEEP_MAX_PAUSE_MS, sample);
        break;
    }
}

static void
CompartmentNameCallback(JSRuntime *rt, JSCompartment *comp,
                        char *buf, size_t bufsize)
{
    nsCString name;
    GetCompartmentName(comp, name, false);
    if (name.Length() >= bufsize)
        name.Truncate(bufsize - 1);
    memcpy(buf, name.get(), name.Length() + 1);
}

static bool
PreserveWrapper(JSContext *cx, JSObject *obj)
{
    MOZ_ASSERT(cx);
    MOZ_ASSERT(obj);
    MOZ_ASSERT(IS_WN_REFLECTOR(obj) || mozilla::dom::IsDOMObject(obj));

    return mozilla::dom::IsDOMObject(obj) && mozilla::dom::TryPreserveWrapper(obj);
}

static nsresult
ReadSourceFromFilename(JSContext *cx, const char *filename, jschar **src, size_t *len)
{
    nsresult rv;

    // mozJSSubScriptLoader prefixes the filenames of the scripts it loads with
    // the filename of its caller. Axe that if present.
    const char *arrow;
    while ((arrow = strstr(filename, " -> ")))
        filename = arrow + strlen(" -> ");

    // Get the URI.
    nsCOMPtr<nsIURI> uri;
    rv = NS_NewURI(getter_AddRefs(uri), filename);
    NS_ENSURE_SUCCESS(rv, rv);

    nsCOMPtr<nsIChannel> scriptChannel;
    rv = NS_NewChannel(getter_AddRefs(scriptChannel), uri);
    NS_ENSURE_SUCCESS(rv, rv);

    // Only allow local reading.
    nsCOMPtr<nsIURI> actualUri;
    rv = scriptChannel->GetURI(getter_AddRefs(actualUri));
    NS_ENSURE_SUCCESS(rv, rv);
    nsCString scheme;
    rv = actualUri->GetScheme(scheme);
    NS_ENSURE_SUCCESS(rv, rv);
    if (!scheme.EqualsLiteral("file") && !scheme.EqualsLiteral("jar"))
        return NS_OK;

    nsCOMPtr<nsIInputStream> scriptStream;
    rv = scriptChannel->Open(getter_AddRefs(scriptStream));
    NS_ENSURE_SUCCESS(rv, rv);

    uint64_t rawLen;
    rv = scriptStream->Available(&rawLen);
    NS_ENSURE_SUCCESS(rv, rv);
    if (!rawLen)
        return NS_ERROR_FAILURE;

    // Technically, this should be SIZE_MAX, but we don't run on machines
    // where that would be less than UINT32_MAX, and the latter is already
    // well beyond a reasonable limit.
    if (rawLen > UINT32_MAX)
        return NS_ERROR_FILE_TOO_BIG;

    // Allocate an internal buf the size of the file.
    nsAutoArrayPtr<unsigned char> buf(new unsigned char[rawLen]);
    if (!buf)
        return NS_ERROR_OUT_OF_MEMORY;

    unsigned char *ptr = buf, *end = ptr + rawLen;
    while (ptr < end) {
        uint32_t bytesRead;
        rv = scriptStream->Read(reinterpret_cast<char *>(ptr), end - ptr, &bytesRead);
        if (NS_FAILED(rv))
            return rv;
        MOZ_ASSERT(bytesRead > 0, "stream promised more bytes before EOF");
        ptr += bytesRead;
    }

    rv = nsScriptLoader::ConvertToUTF16(scriptChannel, buf, rawLen, EmptyString(),
                                        nullptr, *src, *len);
    NS_ENSURE_SUCCESS(rv, rv);

    if (!*src)
        return NS_ERROR_FAILURE;

    // Historically this method used JS_malloc() which updates the GC memory
    // accounting.  Since ConvertToUTF16() now uses js_malloc() instead we
    // update the accounting manually after the fact.
    JS_updateMallocCounter(cx, *len);

    return NS_OK;
}

// The JS engine calls this object's 'load' member function when it needs
// the source for a chrome JS function. See the comment in the XPCJSRuntime
// constructor.
class XPCJSSourceHook: public js::SourceHook {
    bool load(JSContext *cx, const char *filename, jschar **src, size_t *length) {
        *src = nullptr;
        *length = 0;

        if (!nsContentUtils::IsCallerChrome())
            return true;

        if (!filename)
            return true;

        nsresult rv = ReadSourceFromFilename(cx, filename, src, length);
        if (NS_FAILED(rv)) {
            xpc::Throw(cx, rv);
            return false;
        }

        return true;
    }
};

static const JSWrapObjectCallbacks WrapObjectCallbacks = {
    xpc::WrapperFactory::Rewrap,
    xpc::WrapperFactory::PrepareForWrapping
};

XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
   : CycleCollectedJSRuntime(nullptr, JS::DefaultHeapMaxBytes, JS::DefaultNurseryBytes),
   mJSContextStack(new XPCJSContextStack(MOZ_THIS_IN_INITIALIZER_LIST())),
   mCallContext(nullptr),
   mAutoRoots(nullptr),
   mResolveName(JSID_VOID),
   mResolvingWrapper(nullptr),
   mWrappedJSMap(JSObject2WrappedJSMap::newMap(XPC_JS_MAP_SIZE)),
   mWrappedJSClassMap(IID2WrappedJSClassMap::newMap(XPC_JS_CLASS_MAP_SIZE)),
   mIID2NativeInterfaceMap(IID2NativeInterfaceMap::newMap(XPC_NATIVE_INTERFACE_MAP_SIZE)),
   mClassInfo2NativeSetMap(ClassInfo2NativeSetMap::newMap(XPC_NATIVE_SET_MAP_SIZE)),
   mNativeSetMap(NativeSetMap::newMap(XPC_NATIVE_SET_MAP_SIZE)),
   mThisTranslatorMap(IID2ThisTranslatorMap::newMap(XPC_THIS_TRANSLATOR_MAP_SIZE)),
   mNativeScriptableSharedMap(XPCNativeScriptableSharedMap::newMap(XPC_NATIVE_JSCLASS_MAP_SIZE)),
   mDyingWrappedNativeProtoMap(XPCWrappedNativeProtoMap::newMap(XPC_DYING_NATIVE_PROTO_MAP_SIZE)),
   mDetachedWrappedNativeProtoMap(XPCWrappedNativeProtoMap::newMap(XPC_DETACHED_NATIVE_PROTO_MAP_SIZE)),
   mGCIsRunning(false),
   mWrappedJSToReleaseArray(),
   mNativesToReleaseArray(),
   mDoingFinalization(false),
   mVariantRoots(nullptr),
   mWrappedJSRoots(nullptr),
   mObjectHolderRoots(nullptr),
   mWatchdogManager(new WatchdogManager(MOZ_THIS_IN_INITIALIZER_LIST())),
   mJunkScope(MOZ_THIS_IN_INITIALIZER_LIST()->Runtime(), nullptr),
   mCompilationScope(MOZ_THIS_IN_INITIALIZER_LIST()->Runtime(), nullptr),
   mAsyncSnowWhiteFreer(new AsyncFreeSnowWhite())
{
    DOM_InitInterfaces();

    // these jsids filled in later when we have a JSContext to work with.
    mStrIDs[0] = JSID_VOID;

    MOZ_ASSERT(Runtime());
    JSRuntime* runtime = Runtime();

    auto rtPrivate = new PerThreadAtomCache();
    memset(rtPrivate, 0, sizeof(PerThreadAtomCache));
    JS_SetRuntimePrivate(runtime, rtPrivate);

    // Unconstrain the runtime's threshold on nominal heap size, to avoid
    // triggering GC too often if operating continuously near an arbitrary
    // finite threshold (0xffffffff is infinity for uint32_t parameters).
    // This leaves the maximum-JS_malloc-bytes threshold still in effect
    // to cause period, and we hope hygienic, last-ditch GCs from within
    // the GC's allocator.
    JS_SetGCParameter(runtime, JSGC_MAX_BYTES, 0xffffffff);

    // The JS engine permits us to set different stack limits for system code,
    // trusted script, and untrusted script. We have tests that ensure that
    // we can always execute 10 "heavy" (eval+with) stack frames deeper in
    // privileged code. Our stack sizes vary greatly in different configurations,
    // so satisfying those tests requires some care. Manual measurements of the
    // number of heavy stack frames achievable gives us the following rough data,
    // ordered by the effective categories in which they are grouped in the
    // JS_SetNativeStackQuota call (which predates this analysis).
    //
    // (NB: These numbers may have drifted recently - see bug 938429)
    // OSX 64-bit Debug: 7MB stack, 636 stack frames => ~11.3k per stack frame
    // OSX64 Opt: 7MB stack, 2440 stack frames => ~3k per stack frame
    //
    // Linux 32-bit Debug: 2MB stack, 447 stack frames => ~4.6k per stack frame
    // Linux 64-bit Debug: 4MB stack, 501 stack frames => ~8.2k per stack frame
    //
    // Windows (Opt+Debug): 900K stack, 235 stack frames => ~3.4k per stack frame
    //
    // Linux 32-bit Opt: 1MB stack, 272 stack frames => ~3.8k per stack frame
    // Linux 64-bit Opt: 2MB stack, 316 stack frames => ~6.5k per stack frame
    //
    // We tune the trusted/untrusted quotas for each configuration to achieve our
    // invariants while attempting to minimize overhead. In contrast, our buffer
    // between system code and trusted script is a very unscientific 10k.
    const size_t kSystemCodeBuffer = 10 * 1024;

    // Our "default" stack is what we use in configurations where we don't have
    // a compelling reason to do things differently. This is effectively 1MB on
    // 32-bit platforms and 2MB on 64-bit platforms.
    const size_t kDefaultStackQuota = 128 * sizeof(size_t) * 1024;

    // Set stack sizes for different configurations. It's probably not great for
    // the web to base this decision primarily on the default stack size that the
    // underlying platform makes available, but that seems to be what we do. :-(

#if defined(XP_MACOSX) || defined(DARWIN)
    // MacOS has a gargantuan default stack size of 8MB. Go wild with 7MB,
    // and give trusted script 180k extra. The stack is huge on mac anyway.
    const size_t kStackQuota = 7 * 1024 * 1024;
    const size_t kTrustedScriptBuffer = 180 * 1024;
#elif defined(MOZ_ASAN)
    // ASan requires more stack space due to red-zones, so give it double the
    // default (2MB on 32-bit, 4MB on 64-bit). ASAN stack frame measurements
    // were not taken at the time of this writing, so we hazard a guess that
    // ASAN builds have roughly thrice the stack overhead as normal builds.
    // On normal builds, the largest stack frame size we might encounter is
    // 8.2k, so let's use a buffer of 8.2 * 3 * 10 = 246k.
    const size_t kStackQuota =  2 * kDefaultStackQuota;
    const size_t kTrustedScriptBuffer = 246 * 1024;
#elif defined(XP_WIN)
    // 1MB is the default stack size on Windows, so the default 1MB stack quota
    // we'd get on win32 is slightly too large. Use 900k instead. And since
    // windows stack frames are 3.4k each, let's use a buffer of 50k.
    const size_t kStackQuota = 900 * 1024;
    const size_t kTrustedScriptBuffer = 50 * 1024;
    // The following two configurations are linux-only. Given the numbers above,
    // we use 50k and 100k trusted buffers on 32-bit and 64-bit respectively.
#elif defined(DEBUG)
    // Bug 803182: account for the 4x difference in the size of js::Interpret
    // between optimized and debug builds.
    // XXXbholley - Then why do we only account for 2x of difference?
    const size_t kStackQuota = 2 * kDefaultStackQuota;
    const size_t kTrustedScriptBuffer = sizeof(size_t) * 12800;
#else
    const size_t kStackQuota = kDefaultStackQuota;
    const size_t kTrustedScriptBuffer = sizeof(size_t) * 12800;
#endif

    // Avoid an unused variable warning on platforms where we don't use the
    // default.
    (void) kDefaultStackQuota;

    JS_SetNativeStackQuota(runtime,
                           kStackQuota,
                           kStackQuota - kSystemCodeBuffer,
                           kStackQuota - kSystemCodeBuffer - kTrustedScriptBuffer);

    JS_SetDestroyCompartmentCallback(runtime, CompartmentDestroyedCallback);
    JS_SetCompartmentNameCallback(runtime, CompartmentNameCallback);
    mPrevGCSliceCallback = JS::SetGCSliceCallback(runtime, GCSliceCallback);
    JS_AddFinalizeCallback(runtime, FinalizeCallback, nullptr);
    JS_SetWrapObjectCallbacks(runtime, &WrapObjectCallbacks);
    js::SetPreserveWrapperCallback(runtime, PreserveWrapper);
#ifdef MOZ_CRASHREPORTER
    JS_EnumerateDiagnosticMemoryRegions(DiagnosticMemoryCallback);
#endif
#ifdef MOZ_ENABLE_PROFILER_SPS
    if (PseudoStack *stack = mozilla_get_pseudo_stack())
        stack->sampleRuntime(runtime);
#endif
    JS_SetAccumulateTelemetryCallback(runtime, AccumulateTelemetryCallback);
    js::SetDefaultJSContextCallback(runtime, DefaultJSContextCallback);
    js::SetActivityCallback(runtime, ActivityCallback, this);
    js::SetCTypesActivityCallback(runtime, CTypesActivityCallback);
    JS_SetInterruptCallback(runtime, InterruptCallback);

    // The JS engine needs to keep the source code around in order to implement
    // Function.prototype.toSource(). It'd be nice to not have to do this for
    // chrome code and simply stub out requests for source on it. Life is not so
    // easy, unfortunately. Nobody relies on chrome toSource() working in core
    // browser code, but chrome tests use it. The worst offenders are addons,
    // which like to monkeypatch chrome functions by calling toSource() on them
    // and using regular expressions to modify them. We avoid keeping most browser
    // JS source code in memory by setting LAZY_SOURCE on JS::CompileOptions when
    // compiling some chrome code. This causes the JS engine not save the source
    // code in memory. When the JS engine is asked to provide the source for a
    // function compiled with LAZY_SOURCE, it calls SourceHook to load it.
    ///
    // Note we do have to retain the source code in memory for scripts compiled in
    // compileAndGo mode and compiled function bodies (from
    // JS_CompileFunction*). In practice, this means content scripts and event
    // handlers.
    js::SetSourceHook(runtime, new XPCJSSourceHook);

    // Set up locale information and callbacks for the newly-created runtime so
    // that the various toLocaleString() methods, localeCompare(), and other
    // internationalization APIs work as desired.
    if (!xpc_LocalizeRuntime(runtime))
        NS_RUNTIMEABORT("xpc_LocalizeRuntime failed.");

    // Register memory reporters and distinguished amount functions.
    RegisterStrongMemoryReporter(new JSMainRuntimeCompartmentsReporter());
    RegisterStrongMemoryReporter(new JSMainRuntimeTemporaryPeakReporter());
    RegisterJSMainRuntimeGCHeapDistinguishedAmount(JSMainRuntimeGCHeapDistinguishedAmount);
    RegisterJSMainRuntimeTemporaryPeakDistinguishedAmount(JSMainRuntimeTemporaryPeakDistinguishedAmount);
    RegisterJSMainRuntimeCompartmentsSystemDistinguishedAmount(JSMainRuntimeCompartmentsSystemDistinguishedAmount);
    RegisterJSMainRuntimeCompartmentsUserDistinguishedAmount(JSMainRuntimeCompartmentsUserDistinguishedAmount);
    mozilla::RegisterJSSizeOfTab(JSSizeOfTab);

    // Install a JavaScript 'debugger' keyword handler in debug builds only
#ifdef DEBUG
    if (!JS_GetGlobalDebugHooks(runtime)->debuggerHandler)
        xpc_InstallJSDebuggerKeywordHandler(runtime);
#endif

    // Watch for the JS boolean options.
    ReloadPrefsCallback(nullptr, this);
    Preferences::RegisterCallback(ReloadPrefsCallback, JS_OPTIONS_DOT_STR, this);
}

// static
XPCJSRuntime*
XPCJSRuntime::newXPCJSRuntime(nsXPConnect* aXPConnect)
{
    NS_PRECONDITION(aXPConnect,"bad param");

    XPCJSRuntime* self = new XPCJSRuntime(aXPConnect);

    if (self                                    &&
        self->Runtime()                         &&
        self->GetWrappedJSMap()                 &&
        self->GetWrappedJSClassMap()            &&
        self->GetIID2NativeInterfaceMap()       &&
        self->GetClassInfo2NativeSetMap()       &&
        self->GetNativeSetMap()                 &&
        self->GetThisTranslatorMap()            &&
        self->GetNativeScriptableSharedMap()    &&
        self->GetDyingWrappedNativeProtoMap()   &&
        self->mWatchdogManager) {
        return self;
    }

    NS_RUNTIMEABORT("new XPCJSRuntime failed to initialize.");

    delete self;
    return nullptr;
}

bool
XPCJSRuntime::OnJSContextNew(JSContext *cx)
{
    // If we were the first cx ever created (like the SafeJSContext), the caller
    // would have had no way to enter a request. Enter one now before doing the
    // rest of the cx setup.
    JSAutoRequest ar(cx);

    // if it is our first context then we need to generate our string ids
    if (JSID_IS_VOID(mStrIDs[0])) {
        RootedString str(cx);
        for (unsigned i = 0; i < IDX_TOTAL_COUNT; i++) {
            str = JS_InternString(cx, mStrings[i]);
            if (!str) {
                mStrIDs[0] = JSID_VOID;
                return false;
            }
            mStrIDs[i] = INTERNED_STRING_TO_JSID(cx, str);
            mStrJSVals[i] = STRING_TO_JSVAL(str);
        }

        if (!mozilla::dom::DefineStaticJSVals(cx)) {
            return false;
        }
    }

    XPCContext* xpc = new XPCContext(this, cx);
    if (!xpc)
        return false;

    return true;
}

bool
XPCJSRuntime::DescribeCustomObjects(JSObject* obj, const js::Class* clasp,
                                    char (&name)[72]) const
{
    XPCNativeScriptableInfo *si = nullptr;

    if (!IS_PROTO_CLASS(clasp)) {
        return false;
    }

    XPCWrappedNativeProto *p =
        static_cast<XPCWrappedNativeProto*>(xpc_GetJSPrivate(obj));
    si = p->GetScriptableInfo();
    
    if (!si) {
        return false;
    }

    JS_snprintf(name, sizeof(name), "JS Object (%s - %s)",
                clasp->name, si->GetJSClass()->name);
    return true;
}

bool
XPCJSRuntime::NoteCustomGCThingXPCOMChildren(const js::Class* clasp, JSObject* obj,
                                             nsCycleCollectionTraversalCallback& cb) const
{
    if (clasp != &XPC_WN_Tearoff_JSClass) {
        return false;
    }

    // A tearoff holds a strong reference to its native object
    // (see XPCWrappedNative::FlatJSObjectFinalized). Its XPCWrappedNative
    // will be held alive through the parent of the JSObject of the tearoff.
    XPCWrappedNativeTearOff *to =
        static_cast<XPCWrappedNativeTearOff*>(xpc_GetJSPrivate(obj));
    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "xpc_GetJSPrivate(obj)->mNative");
    cb.NoteXPCOMChild(to->GetNative());
    return true;
}

/***************************************************************************/

#ifdef DEBUG
static PLDHashOperator
WrappedJSClassMapDumpEnumerator(PLDHashTable *table, PLDHashEntryHdr *hdr,
                                uint32_t number, void *arg)
{
    ((IID2WrappedJSClassMap::Entry*)hdr)->value->DebugDump(*(int16_t*)arg);
    return PL_DHASH_NEXT;
}
static PLDHashOperator
NativeSetDumpEnumerator(PLDHashTable *table, PLDHashEntryHdr *hdr,
                        uint32_t number, void *arg)
{
    ((NativeSetMap::Entry*)hdr)->key_value->DebugDump(*(int16_t*)arg);
    return PL_DHASH_NEXT;
}
#endif

void
XPCJSRuntime::DebugDump(int16_t depth)
{
#ifdef DEBUG
    depth--;
    XPC_LOG_ALWAYS(("XPCJSRuntime @ %x", this));
        XPC_LOG_INDENT();
        XPC_LOG_ALWAYS(("mJSRuntime @ %x", Runtime()));

        XPC_LOG_ALWAYS(("mWrappedJSToReleaseArray @ %x with %d wrappers(s)", \
                        &mWrappedJSToReleaseArray,
                        mWrappedJSToReleaseArray.Length()));

        int cxCount = 0;
        JSContext* iter = nullptr;
        while (JS_ContextIterator(Runtime(), &iter))
            ++cxCount;
        XPC_LOG_ALWAYS(("%d JS context(s)", cxCount));

        iter = nullptr;
        while (JS_ContextIterator(Runtime(), &iter)) {
            XPCContext *xpc = XPCContext::GetXPCContext(iter);
            XPC_LOG_INDENT();
            xpc->DebugDump(depth);
            XPC_LOG_OUTDENT();
        }

        XPC_LOG_ALWAYS(("mWrappedJSClassMap @ %x with %d wrapperclasses(s)",  \
                        mWrappedJSClassMap, mWrappedJSClassMap ?              \
                        mWrappedJSClassMap->Count() : 0));
        // iterate wrappersclasses...
        if (depth && mWrappedJSClassMap && mWrappedJSClassMap->Count()) {
            XPC_LOG_INDENT();
            mWrappedJSClassMap->Enumerate(WrappedJSClassMapDumpEnumerator, &depth);
            XPC_LOG_OUTDENT();
        }
        XPC_LOG_ALWAYS(("mWrappedJSMap @ %x with %d wrappers(s)",             \
                        mWrappedJSMap, mWrappedJSMap ?                        \
                        mWrappedJSMap->Count() : 0));
        // iterate wrappers...
        if (depth && mWrappedJSMap && mWrappedJSMap->Count()) {
            XPC_LOG_INDENT();
            mWrappedJSMap->Dump(depth);
            XPC_LOG_OUTDENT();
        }

        XPC_LOG_ALWAYS(("mIID2NativeInterfaceMap @ %x with %d interface(s)",  \
                        mIID2NativeInterfaceMap, mIID2NativeInterfaceMap ?    \
                        mIID2NativeInterfaceMap->Count() : 0));

        XPC_LOG_ALWAYS(("mClassInfo2NativeSetMap @ %x with %d sets(s)",       \
                        mClassInfo2NativeSetMap, mClassInfo2NativeSetMap ?    \
                        mClassInfo2NativeSetMap->Count() : 0));

        XPC_LOG_ALWAYS(("mThisTranslatorMap @ %x with %d translator(s)",      \
                        mThisTranslatorMap, mThisTranslatorMap ?              \
                        mThisTranslatorMap->Count() : 0));

        XPC_LOG_ALWAYS(("mNativeSetMap @ %x with %d sets(s)",                 \
                        mNativeSetMap, mNativeSetMap ?                        \
                        mNativeSetMap->Count() : 0));

        // iterate sets...
        if (depth && mNativeSetMap && mNativeSetMap->Count()) {
            XPC_LOG_INDENT();
            mNativeSetMap->Enumerate(NativeSetDumpEnumerator, &depth);
            XPC_LOG_OUTDENT();
        }

        XPC_LOG_OUTDENT();
#endif
}

/***************************************************************************/

void
XPCRootSetElem::AddToRootSet(XPCRootSetElem **listHead)
{
    MOZ_ASSERT(!mSelfp, "Must be not linked");

    mSelfp = listHead;
    mNext = *listHead;
    if (mNext) {
        MOZ_ASSERT(mNext->mSelfp == listHead, "Must be list start");
        mNext->mSelfp = &mNext;
    }
    *listHead = this;
}

void
XPCRootSetElem::RemoveFromRootSet()
{
    nsXPConnect *xpc = nsXPConnect::XPConnect();
    JS::PokeGC(xpc->GetRuntime()->Runtime());

    MOZ_ASSERT(mSelfp, "Must be linked");

    MOZ_ASSERT(*mSelfp == this, "Link invariant");
    *mSelfp = mNext;
    if (mNext)
        mNext->mSelfp = mSelfp;
#ifdef DEBUG
    mSelfp = nullptr;
    mNext = nullptr;
#endif
}

void
XPCJSRuntime::AddGCCallback(xpcGCCallback cb)
{
    MOZ_ASSERT(cb, "null callback");
    extraGCCallbacks.AppendElement(cb);
}

void
XPCJSRuntime::RemoveGCCallback(xpcGCCallback cb)
{
    MOZ_ASSERT(cb, "null callback");
    bool found = extraGCCallbacks.RemoveElement(cb);
    if (!found) {
        NS_ERROR("Removing a callback which was never added.");
    }
}

void
XPCJSRuntime::AddContextCallback(xpcContextCallback cb)
{
    MOZ_ASSERT(cb, "null callback");
    extraContextCallbacks.AppendElement(cb);
}

void
XPCJSRuntime::RemoveContextCallback(xpcContextCallback cb)
{
    MOZ_ASSERT(cb, "null callback");
    bool found = extraContextCallbacks.RemoveElement(cb);
    if (!found) {
        NS_ERROR("Removing a callback which was never added.");
    }
}

JSObject *
XPCJSRuntime::GetJunkScope()
{
    if (!mJunkScope) {
        AutoSafeJSContext cx;
        SandboxOptions options;
        options.sandboxName.AssignLiteral("XPConnect Junk Compartment");
        RootedValue v(cx);
        nsresult rv = CreateSandboxObject(cx, &v, nsContentUtils::GetSystemPrincipal(), options);
        NS_ENSURE_SUCCESS(rv, nullptr);

        mJunkScope = js::UncheckedUnwrap(&v.toObject());
    }
    return mJunkScope;
}

JSObject *
XPCJSRuntime::GetCompilationScope()
{
    if (!mCompilationScope) {
        AutoSafeJSContext cx;
        SandboxOptions options;
        options.sandboxName.AssignLiteral("XPConnect Compilation Compartment");
        options.invisibleToDebugger = true;
        options.discardSource = ShouldDiscardSystemSource();
        RootedValue v(cx);
        nsresult rv = CreateSandboxObject(cx, &v, /* principal = */ nullptr, options);
        NS_ENSURE_SUCCESS(rv, nullptr);

        mCompilationScope = js::UncheckedUnwrap(&v.toObject());
    }
    return mCompilationScope;
}


void
XPCJSRuntime::DeleteSingletonScopes()
{
    mJunkScope = nullptr;
    mCompilationScope = nullptr;
}