hal/HalWakeLock.cpp
author Kartikaya Gupta <kgupta@mozilla.com>
Mon, 31 Jul 2017 15:27:29 -0400
changeset 423152 509e1cc89fb526ff0b232f9ed3a49127e84bdd7c
parent 343599 232a786cf87fb0f68f9bda6e9316515524d2ac8a
child 492396 7296296be48395ff3fd0706364b72cec35b2774e
permissions -rw-r--r--
Bug 1384616 - Change how display items put their APZ-relevant info into the WebRenderScrollData. r=jrmuizel Instead of the WebRenderLayerScrollData code knowing about all the different display item types, it makes more sense to move this logic into the display items. In addition to avoiding dis-encapsulating the data from nsDisplayItem subclasses, this makes it easier to handle two specific scenarios: (1) the case where an nsDisplayItem A subclasses another nsDisplayItem B, but A and B have different types returned by GetType(). Previously A and B would have to be handled explicitly in the WebRenderLayerScrollData switch statements, which doesn't scale well if new types are added. With the new approach the virtual function is shared down from A to B and so takes care of it. This is particularly relevant for types like nsDisplayOwnLayer which have a number of subclasses. (2) the case where a display item *might* have APZ-relevant information. In this case the type of the item alone is not sufficient to determine if we need to create a new WebRenderLayerScrollData for it. Instead, we need to access specific state inside the display item. This is now handled by the UpdateScrollData function returning true when passed nullptr arguments, and replaces the switch statement in WebRenderLayerManager that updated forceNewLayerData. MozReview-Commit-ID: FlfHlgSccSn

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "Hal.h"
#include "mozilla/HalWakeLock.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/dom/ContentParent.h"
#include "nsAutoPtr.h"
#include "nsClassHashtable.h"
#include "nsDataHashtable.h"
#include "nsHashKeys.h"
#include "nsIPropertyBag2.h"
#include "nsIObserverService.h"

using namespace mozilla;
using namespace mozilla::hal;

namespace {

struct LockCount {
  LockCount()
    : numLocks(0)
    , numHidden(0)
  {}
  uint32_t numLocks;
  uint32_t numHidden;
  nsTArray<uint64_t> processes;
};

typedef nsDataHashtable<nsUint64HashKey, LockCount> ProcessLockTable;
typedef nsClassHashtable<nsStringHashKey, ProcessLockTable> LockTable;

int sActiveListeners = 0;
StaticAutoPtr<LockTable> sLockTable;
bool sInitialized = false;
bool sIsShuttingDown = false;

WakeLockInformation
WakeLockInfoFromLockCount(const nsAString& aTopic, const LockCount& aLockCount)
{
  // TODO: Once we abandon b2g18, we can switch this to use the
  // WakeLockInformation constructor, which is better because it doesn't let us
  // forget to assign a param.  For now we have to do it this way, because
  // b2g18 doesn't have the nsTArray <--> InfallibleTArray conversion (bug
  // 819791).

  WakeLockInformation info;
  info.topic() = aTopic;
  info.numLocks() = aLockCount.numLocks;
  info.numHidden() = aLockCount.numHidden;
  info.lockingProcesses().AppendElements(aLockCount.processes);
  return info;
}

static void
CountWakeLocks(ProcessLockTable* aTable, LockCount* aTotalCount)
{
  for (auto iter = aTable->Iter(); !iter.Done(); iter.Next()) {
    const uint64_t& key = iter.Key();
    LockCount count = iter.UserData();

    aTotalCount->numLocks += count.numLocks;
    aTotalCount->numHidden += count.numHidden;

    // This is linear in the number of processes, but that should be small.
    if (!aTotalCount->processes.Contains(key)) {
      aTotalCount->processes.AppendElement(key);
    }
  }
}

class ClearHashtableOnShutdown final : public nsIObserver {
  ~ClearHashtableOnShutdown() {}
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIOBSERVER
};

NS_IMPL_ISUPPORTS(ClearHashtableOnShutdown, nsIObserver)

NS_IMETHODIMP
ClearHashtableOnShutdown::Observe(nsISupports* aSubject, const char* aTopic, const char16_t* data)
{
  MOZ_ASSERT(!strcmp(aTopic, "xpcom-shutdown"));

  sIsShuttingDown = true;
  sLockTable = nullptr;

  return NS_OK;
}

class CleanupOnContentShutdown final : public nsIObserver {
  ~CleanupOnContentShutdown() {}
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIOBSERVER
};

NS_IMPL_ISUPPORTS(CleanupOnContentShutdown, nsIObserver)

NS_IMETHODIMP
CleanupOnContentShutdown::Observe(nsISupports* aSubject, const char* aTopic, const char16_t* data)
{
  MOZ_ASSERT(!strcmp(aTopic, "ipc:content-shutdown"));

  if (sIsShuttingDown) {
    return NS_OK;
  }

  nsCOMPtr<nsIPropertyBag2> props = do_QueryInterface(aSubject);
  if (!props) {
    NS_WARNING("ipc:content-shutdown message without property bag as subject");
    return NS_OK;
  }

  uint64_t childID = 0;
  nsresult rv = props->GetPropertyAsUint64(NS_LITERAL_STRING("childID"),
                                           &childID);
  if (NS_SUCCEEDED(rv)) {
    for (auto iter = sLockTable->Iter(); !iter.Done(); iter.Next()) {
      nsAutoPtr<ProcessLockTable>& table = iter.Data();

      if (table->Get(childID, nullptr)) {
        table->Remove(childID);

        LockCount totalCount;
        CountWakeLocks(table, &totalCount);

        if (sActiveListeners) {
          NotifyWakeLockChange(WakeLockInfoFromLockCount(iter.Key(),
                                                         totalCount));
        }

        if (totalCount.numLocks == 0) {
          iter.Remove();
        }
      }
    }
  } else {
    NS_WARNING("ipc:content-shutdown message without childID property");
  }
  return NS_OK;
}

void
Init()
{
  sLockTable = new LockTable();
  sInitialized = true;

  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
  if (obs) {
    obs->AddObserver(new ClearHashtableOnShutdown(), "xpcom-shutdown", false);
    obs->AddObserver(new CleanupOnContentShutdown(), "ipc:content-shutdown", false);
  }
}

} // namespace

namespace mozilla {

namespace hal {

WakeLockState
ComputeWakeLockState(int aNumLocks, int aNumHidden)
{
  if (aNumLocks == 0) {
    return WAKE_LOCK_STATE_UNLOCKED;
  } else if (aNumLocks == aNumHidden) {
    return WAKE_LOCK_STATE_HIDDEN;
  } else {
    return WAKE_LOCK_STATE_VISIBLE;
  }
}

} // namespace hal

namespace hal_impl {

void
EnableWakeLockNotifications()
{
  sActiveListeners++;
}

void
DisableWakeLockNotifications()
{
  sActiveListeners--;
}

void
ModifyWakeLock(const nsAString& aTopic,
               hal::WakeLockControl aLockAdjust,
               hal::WakeLockControl aHiddenAdjust,
               uint64_t aProcessID)
{
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aProcessID != CONTENT_PROCESS_ID_UNKNOWN);

  if (sIsShuttingDown) {
    return;
  }
  if (!sInitialized) {
    Init();
  }

  ProcessLockTable* table = sLockTable->Get(aTopic);
  LockCount processCount;
  LockCount totalCount;
  if (!table) {
    table = new ProcessLockTable();
    sLockTable->Put(aTopic, table);
  } else {
    table->Get(aProcessID, &processCount);
    CountWakeLocks(table, &totalCount);
  }

  MOZ_ASSERT(processCount.numLocks >= processCount.numHidden);
  MOZ_ASSERT(aLockAdjust >= 0 || processCount.numLocks > 0);
  MOZ_ASSERT(aHiddenAdjust >= 0 || processCount.numHidden > 0);
  MOZ_ASSERT(totalCount.numLocks >= totalCount.numHidden);
  MOZ_ASSERT(aLockAdjust >= 0 || totalCount.numLocks > 0);
  MOZ_ASSERT(aHiddenAdjust >= 0 || totalCount.numHidden > 0);

  WakeLockState oldState = ComputeWakeLockState(totalCount.numLocks, totalCount.numHidden);
  bool processWasLocked = processCount.numLocks > 0;

  processCount.numLocks += aLockAdjust;
  processCount.numHidden += aHiddenAdjust;

  totalCount.numLocks += aLockAdjust;
  totalCount.numHidden += aHiddenAdjust;

  if (processCount.numLocks) {
    table->Put(aProcessID, processCount);
  } else {
    table->Remove(aProcessID);
  }
  if (!totalCount.numLocks) {
    sLockTable->Remove(aTopic);
  }

  if (sActiveListeners &&
      (oldState != ComputeWakeLockState(totalCount.numLocks,
                                        totalCount.numHidden) ||
       processWasLocked != (processCount.numLocks > 0))) {

    WakeLockInformation info;
    hal::GetWakeLockInfo(aTopic, &info);
    NotifyWakeLockChange(info);
  }
}

void
GetWakeLockInfo(const nsAString& aTopic, WakeLockInformation* aWakeLockInfo)
{
  if (sIsShuttingDown) {
    NS_WARNING("You don't want to get wake lock information during xpcom-shutdown!");
    *aWakeLockInfo = WakeLockInformation();
    return;
  }
  if (!sInitialized) {
    Init();
  }

  ProcessLockTable* table = sLockTable->Get(aTopic);
  if (!table) {
    *aWakeLockInfo = WakeLockInfoFromLockCount(aTopic, LockCount());
    return;
  }
  LockCount totalCount;
  CountWakeLocks(table, &totalCount);
  *aWakeLockInfo = WakeLockInfoFromLockCount(aTopic, totalCount);
}

} // namespace hal_impl
} // namespace mozilla