xpcom/io/nsInputStreamTee.cpp
author Jan Henning <jh+bugzilla@buttercookie.de>
Thu, 07 Feb 2019 20:41:16 +0000
changeset 512996 95b884dcbd6f001b990a6353980280050fab9ac6
parent 511623 5f4630838d46dd81dadb13220a4af0da9e23a619
permissions -rw-r--r--
Bug 1496684 - Dispatch commonly expected startup notifications when opening a GeckoView window. r=snorp a=lizzard Once a webextension using a blocking WebRequest listener has started loading, all network connections covered by the extension's manifest are held until the extension is ready the process them. One condition for the extension being ready apparently includes browser startup having progressed far enough, as signified by "browser-delayed-startup-finished" having been dispatched. Therefore, we have to start sending that notification when opening a new Gecko- View window, too, and copy Fennec's InitLater() system for that. Unlike Fennec, we cannot tie registration of those InitLater() runnables to the initial content load having progressed far enough because of a) e10s, which makes that approach neither easily possible nor really sensible, as content will load in a different process in that case, and b) because we're racing with extension startup here - if extensions are loaded quick enough to block even the initial page load, we'd be deadlocked: We cannot send the notification until the page finishes loading, but the page cannot load until we send the notification. Fennec isn't affected by the latter problem because "sessionstore-windows-restored", which Fennec will send in any case, serves as an alternative pathway for completing extension startup. And unlike Desktop, we don't really have any chrome content to paint, so we cannot tie delayed initialisation to a paint listener for that, either. Therefore, we simply fire off a runnable at the *end* of geckoview.js's startup() method, which should give more pressing initialisation tasks enough of a headstart. For completeness, we're also adding the "browser-idle-startup-tasks-finished" notification and thereby solve bug 1465832 as well, allowing the ScriptPreloader to detect which scripts are commonly loaded during GeckoView startup and to start caching and pre-parsing them. Differential Revision: https://phabricator.services.mozilla.com/D18865

/* -*- 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 <stdlib.h>
#include "mozilla/Logging.h"

#include "mozilla/Mutex.h"
#include "mozilla/Attributes.h"
#include "nsIInputStreamTee.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include "nsIEventTarget.h"
#include "nsThreadUtils.h"

using namespace mozilla;

#ifdef LOG
#  undef LOG
#endif

static LazyLogModule sTeeLog("nsInputStreamTee");
#define LOG(args) MOZ_LOG(sTeeLog, mozilla::LogLevel::Debug, args)

class nsInputStreamTee final : public nsIInputStreamTee {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIINPUTSTREAM
  NS_DECL_NSIINPUTSTREAMTEE

  nsInputStreamTee();
  bool SinkIsValid();
  void InvalidateSink();

 private:
  ~nsInputStreamTee() {}

  nsresult TeeSegment(const char* aBuf, uint32_t aCount);

  static nsresult WriteSegmentFun(nsIInputStream*, void*, const char*, uint32_t,
                                  uint32_t, uint32_t*);

 private:
  nsCOMPtr<nsIInputStream> mSource;
  nsCOMPtr<nsIOutputStream> mSink;
  nsCOMPtr<nsIEventTarget> mEventTarget;
  nsWriteSegmentFun mWriter;  // for implementing ReadSegments
  void* mClosure;             // for implementing ReadSegments
  nsAutoPtr<Mutex> mLock;     // synchronize access to mSinkIsValid
  bool mSinkIsValid;          // False if TeeWriteEvent fails
};

class nsInputStreamTeeWriteEvent : public Runnable {
 public:
  // aTee's lock is held across construction of this object
  nsInputStreamTeeWriteEvent(const char* aBuf, uint32_t aCount,
                             nsIOutputStream* aSink, nsInputStreamTee* aTee)
      : mozilla::Runnable("nsInputStreamTeeWriteEvent") {
    // copy the buffer - will be free'd by dtor
    mBuf = (char*)malloc(aCount);
    if (mBuf) {
      memcpy(mBuf, (char*)aBuf, aCount);
    }
    mCount = aCount;
    mSink = aSink;
    bool isNonBlocking;
    mSink->IsNonBlocking(&isNonBlocking);
    NS_ASSERTION(isNonBlocking == false, "mSink is nonblocking");
    mTee = aTee;
  }

  NS_IMETHOD Run() override {
    if (!mBuf) {
      NS_WARNING(
          "nsInputStreamTeeWriteEvent::Run() "
          "memory not allocated\n");
      return NS_OK;
    }
    MOZ_ASSERT(mSink, "mSink is null!");

    //  The output stream could have been invalidated between when
    //  this event was dispatched and now, so check before writing.
    if (!mTee->SinkIsValid()) {
      return NS_OK;
    }

    LOG(
        ("nsInputStreamTeeWriteEvent::Run() [%p]"
         "will write %u bytes to %p\n",
         this, mCount, mSink.get()));

    uint32_t totalBytesWritten = 0;
    while (mCount) {
      nsresult rv;
      uint32_t bytesWritten = 0;
      rv = mSink->Write(mBuf + totalBytesWritten, mCount, &bytesWritten);
      if (NS_FAILED(rv)) {
        LOG(("nsInputStreamTeeWriteEvent::Run[%p] error %" PRIx32 " in writing",
             this, static_cast<uint32_t>(rv)));
        mTee->InvalidateSink();
        break;
      }
      totalBytesWritten += bytesWritten;
      NS_ASSERTION(bytesWritten <= mCount, "wrote too much");
      mCount -= bytesWritten;
    }
    return NS_OK;
  }

 protected:
  virtual ~nsInputStreamTeeWriteEvent() {
    if (mBuf) {
      free(mBuf);
    }
    mBuf = nullptr;
  }

 private:
  char* mBuf;
  uint32_t mCount;
  nsCOMPtr<nsIOutputStream> mSink;
  // back pointer to the tee that created this runnable
  RefPtr<nsInputStreamTee> mTee;
};

nsInputStreamTee::nsInputStreamTee()
    : mWriter(nullptr), mClosure(nullptr), mLock(nullptr), mSinkIsValid(true) {}

bool nsInputStreamTee::SinkIsValid() {
  MutexAutoLock lock(*mLock);
  return mSinkIsValid;
}

void nsInputStreamTee::InvalidateSink() {
  MutexAutoLock lock(*mLock);
  mSinkIsValid = false;
}

nsresult nsInputStreamTee::TeeSegment(const char* aBuf, uint32_t aCount) {
  if (!mSink) {
    return NS_OK;  // nothing to do
  }
  if (mLock) {  // asynchronous case
    NS_ASSERTION(mEventTarget, "mEventTarget is null, mLock is not null.");
    if (!SinkIsValid()) {
      return NS_OK;  // nothing to do
    }
    nsCOMPtr<nsIRunnable> event =
        new nsInputStreamTeeWriteEvent(aBuf, aCount, mSink, this);
    LOG(("nsInputStreamTee::TeeSegment [%p] dispatching write %u bytes\n", this,
         aCount));
    return mEventTarget->Dispatch(event, NS_DISPATCH_NORMAL);
  } else {  // synchronous case
    NS_ASSERTION(!mEventTarget, "mEventTarget is not null, mLock is null.");
    nsresult rv;
    uint32_t totalBytesWritten = 0;
    while (aCount) {
      uint32_t bytesWritten = 0;
      rv = mSink->Write(aBuf + totalBytesWritten, aCount, &bytesWritten);
      if (NS_FAILED(rv)) {
        // ok, this is not a fatal error... just drop our reference to mSink
        // and continue on as if nothing happened.
        NS_WARNING("Write failed (non-fatal)");
        // catch possible misuse of the input stream tee
        NS_ASSERTION(rv != NS_BASE_STREAM_WOULD_BLOCK,
                     "sink must be a blocking stream");
        mSink = nullptr;
        break;
      }
      totalBytesWritten += bytesWritten;
      NS_ASSERTION(bytesWritten <= aCount, "wrote too much");
      aCount -= bytesWritten;
    }
    return NS_OK;
  }
}

nsresult nsInputStreamTee::WriteSegmentFun(nsIInputStream* aIn, void* aClosure,
                                           const char* aFromSegment,
                                           uint32_t aOffset, uint32_t aCount,
                                           uint32_t* aWriteCount) {
  nsInputStreamTee* tee = reinterpret_cast<nsInputStreamTee*>(aClosure);
  nsresult rv = tee->mWriter(aIn, tee->mClosure, aFromSegment, aOffset, aCount,
                             aWriteCount);
  if (NS_FAILED(rv) || (*aWriteCount == 0)) {
    NS_ASSERTION((NS_FAILED(rv) ? (*aWriteCount == 0) : true),
                 "writer returned an error with non-zero writeCount");
    return rv;
  }

  return tee->TeeSegment(aFromSegment, *aWriteCount);
}

NS_IMPL_ISUPPORTS(nsInputStreamTee, nsIInputStreamTee, nsIInputStream)
NS_IMETHODIMP
nsInputStreamTee::Close() {
  if (NS_WARN_IF(!mSource)) {
    return NS_ERROR_NOT_INITIALIZED;
  }
  nsresult rv = mSource->Close();
  mSource = nullptr;
  mSink = nullptr;
  return rv;
}

NS_IMETHODIMP
nsInputStreamTee::Available(uint64_t* aAvail) {
  if (NS_WARN_IF(!mSource)) {
    return NS_ERROR_NOT_INITIALIZED;
  }
  return mSource->Available(aAvail);
}

NS_IMETHODIMP
nsInputStreamTee::Read(char* aBuf, uint32_t aCount, uint32_t* aBytesRead) {
  if (NS_WARN_IF(!mSource)) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  nsresult rv = mSource->Read(aBuf, aCount, aBytesRead);
  if (NS_FAILED(rv) || (*aBytesRead == 0)) {
    return rv;
  }

  return TeeSegment(aBuf, *aBytesRead);
}

NS_IMETHODIMP
nsInputStreamTee::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
                               uint32_t aCount, uint32_t* aBytesRead) {
  if (NS_WARN_IF(!mSource)) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  mWriter = aWriter;
  mClosure = aClosure;

  return mSource->ReadSegments(WriteSegmentFun, this, aCount, aBytesRead);
}

NS_IMETHODIMP
nsInputStreamTee::IsNonBlocking(bool* aResult) {
  if (NS_WARN_IF(!mSource)) {
    return NS_ERROR_NOT_INITIALIZED;
  }
  return mSource->IsNonBlocking(aResult);
}

NS_IMETHODIMP
nsInputStreamTee::SetSource(nsIInputStream* aSource) {
  mSource = aSource;
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTee::GetSource(nsIInputStream** aSource) {
  NS_IF_ADDREF(*aSource = mSource);
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTee::SetSink(nsIOutputStream* aSink) {
#ifdef DEBUG
  if (aSink) {
    bool nonBlocking;
    nsresult rv = aSink->IsNonBlocking(&nonBlocking);
    if (NS_FAILED(rv) || nonBlocking) {
      NS_ERROR("aSink should be a blocking stream");
    }
  }
#endif
  mSink = aSink;
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTee::GetSink(nsIOutputStream** aSink) {
  NS_IF_ADDREF(*aSink = mSink);
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTee::SetEventTarget(nsIEventTarget* aEventTarget) {
  mEventTarget = aEventTarget;
  if (mEventTarget) {
    // Only need synchronization if this is an async tee
    mLock = new Mutex("nsInputStreamTee.mLock");
  }
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTee::GetEventTarget(nsIEventTarget** aEventTarget) {
  NS_IF_ADDREF(*aEventTarget = mEventTarget);
  return NS_OK;
}

nsresult NS_NewInputStreamTeeAsync(nsIInputStream** aResult,
                                   nsIInputStream* aSource,
                                   nsIOutputStream* aSink,
                                   nsIEventTarget* aEventTarget) {
  nsresult rv;

  nsCOMPtr<nsIInputStreamTee> tee = new nsInputStreamTee();
  rv = tee->SetSource(aSource);
  if (NS_FAILED(rv)) {
    return rv;
  }

  rv = tee->SetSink(aSink);
  if (NS_FAILED(rv)) {
    return rv;
  }

  rv = tee->SetEventTarget(aEventTarget);
  if (NS_FAILED(rv)) {
    return rv;
  }

  tee.forget(aResult);
  return rv;
}

nsresult NS_NewInputStreamTee(nsIInputStream** aResult, nsIInputStream* aSource,
                              nsIOutputStream* aSink) {
  return NS_NewInputStreamTeeAsync(aResult, aSource, aSink, nullptr);
}

#undef LOG