dom/media/MediaShutdownManager.cpp
author Marian-Vasile Laza <mlaza@mozilla.com>
Tue, 30 Nov 2021 23:30:59 +0200
changeset 600683 15c1262d6e8f4524fa63dcc9cc2572038ffb3a92
parent 599368 af9895bca33c5e4fcda06347f21b825d672f91b6
permissions -rw-r--r--
Backed out 6 changesets (bug 1715892, bug 1719735) for causing bc test failures. CLOSED TREE Backed out changeset 196952bd8c9c (bug 1715892) Backed out changeset 9105fe01c025 (bug 1715892) Backed out changeset 4c15d1a24ccd (bug 1715892) Backed out changeset 2c328b84285f (bug 1715892) Backed out changeset 8fcdcdf44b62 (bug 1719735) Backed out changeset c48f398e301f (bug 1719735)

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "MediaShutdownManager.h"

#include "MediaDecoder.h"
#include "mozilla/Logging.h"
#include "mozilla/media/MediaUtils.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPtr.h"
#include "nsComponentManagerUtils.h"
#include "nsIWritablePropertyBag2.h"

namespace mozilla {

#undef LOGW

extern LazyLogModule gMediaDecoderLog;
#define DECODER_LOG(type, msg) MOZ_LOG(gMediaDecoderLog, type, msg)
#define LOGW(...) NS_WARNING(nsPrintfCString(__VA_ARGS__).get())

NS_IMPL_ISUPPORTS(MediaShutdownManager, nsIAsyncShutdownBlocker)

MediaShutdownManager::MediaShutdownManager() {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_DIAGNOSTIC_ASSERT(sInitPhase == NotInited);
}

MediaShutdownManager::~MediaShutdownManager() { MOZ_ASSERT(NS_IsMainThread()); }

// Note that we don't use ClearOnShutdown() on this StaticRefPtr, as that
// may interfere with our shutdown listener.
StaticRefPtr<MediaShutdownManager> MediaShutdownManager::sInstance;

MediaShutdownManager::InitPhase MediaShutdownManager::sInitPhase =
    MediaShutdownManager::NotInited;

MediaShutdownManager& MediaShutdownManager::Instance() {
  MOZ_ASSERT(NS_IsMainThread());
#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
  if (!sInstance) {
    MOZ_CRASH_UNSAFE_PRINTF("sInstance is null. sInitPhase=%d",
                            int(sInitPhase));
  }
#endif
  return *sInstance;
}

void MediaShutdownManager::InitStatics() {
  MOZ_ASSERT(NS_IsMainThread());
  if (sInitPhase != NotInited) {
    return;
  }

  sInstance = new MediaShutdownManager();
  MOZ_DIAGNOSTIC_ASSERT(sInstance);

  nsCOMPtr<nsIAsyncShutdownClient> barrier = media::GetShutdownBarrier();

  if (!barrier) {
    LOGW("Failed to get barrier, cannot add shutdown blocker!");
    sInitPhase = InitFailed;
    return;
  }

  nsresult rv =
      barrier->AddBlocker(sInstance, NS_LITERAL_STRING_FROM_CSTRING(__FILE__),
                          __LINE__, u"MediaShutdownManager shutdown"_ns);
  if (NS_FAILED(rv)) {
    LOGW("Failed to add shutdown blocker! rv=%x", uint32_t(rv));
    sInitPhase = InitFailed;
    return;
  }
  sInitPhase = InitSucceeded;
}

void MediaShutdownManager::RemoveBlocker() {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_DIAGNOSTIC_ASSERT(sInitPhase == XPCOMShutdownStarted);
  MOZ_ASSERT(mDecoders.Count() == 0);
  nsCOMPtr<nsIAsyncShutdownClient> barrier = media::GetShutdownBarrier();
  // xpcom should still be available because we blocked shutdown by having a
  // blocker. Until it completely shuts down we should still be able to get
  // the barrier.
  MOZ_RELEASE_ASSERT(
      barrier,
      "Failed to get shutdown barrier, cannot remove shutdown blocker!");
  barrier->RemoveBlocker(this);
  // Clear our singleton reference. This will probably delete
  // this instance, so don't deref |this| clearing sInstance.
  sInitPhase = XPCOMShutdownEnded;
  sInstance = nullptr;
  DECODER_LOG(LogLevel::Debug, ("MediaShutdownManager::BlockShutdown() end."));
}

nsresult MediaShutdownManager::Register(MediaDecoder* aDecoder) {
  MOZ_ASSERT(NS_IsMainThread());
  if (sInitPhase == InitFailed) {
    return NS_ERROR_NOT_INITIALIZED;
  }
  if (sInitPhase == XPCOMShutdownStarted) {
    return NS_ERROR_ABORT;
  }
  // Don't call Register() after you've Unregistered() all the decoders,
  // that's not going to work.
  MOZ_ASSERT(!mDecoders.Contains(aDecoder));
  mDecoders.Insert(aDecoder);
  MOZ_ASSERT(mDecoders.Contains(aDecoder));
  MOZ_ASSERT(mDecoders.Count() > 0);
  return NS_OK;
}

void MediaShutdownManager::Unregister(MediaDecoder* aDecoder) {
  MOZ_ASSERT(NS_IsMainThread());
  if (!mDecoders.EnsureRemoved(aDecoder)) {
    return;
  }
  if (sInitPhase == XPCOMShutdownStarted && mDecoders.Count() == 0) {
    RemoveBlocker();
  }
}

NS_IMETHODIMP
MediaShutdownManager::GetName(nsAString& aName) {
  aName = u"MediaShutdownManager: shutdown"_ns;
  return NS_OK;
}

NS_IMETHODIMP
MediaShutdownManager::GetState(nsIPropertyBag** aBagOut) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(aBagOut);

  nsCOMPtr<nsIWritablePropertyBag2> propertyBag =
      do_CreateInstance("@mozilla.org/hash-property-bag;1");

  if (NS_WARN_IF(!propertyBag)) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  nsresult rv = propertyBag->SetPropertyAsInt32(
      u"sInitPhase"_ns, static_cast<int32_t>(sInitPhase));

  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsAutoCString decoderInfo;
  for (const auto& key : mDecoders) {
    // Grab the full extended type for the decoder. This can be used to help
    // indicate problems with specific decoders by associating type -> decoder.
    decoderInfo.Append(key->ContainerType().ExtendedType().OriginalString());
    decoderInfo.Append(", ");
  }

  rv = propertyBag->SetPropertyAsACString(u"decoderInfo"_ns, decoderInfo);

  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  propertyBag.forget(aBagOut);

  return NS_OK;
}

NS_IMETHODIMP
MediaShutdownManager::BlockShutdown(nsIAsyncShutdownClient*) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_DIAGNOSTIC_ASSERT(sInitPhase == InitSucceeded);
  MOZ_DIAGNOSTIC_ASSERT(sInstance);

  DECODER_LOG(LogLevel::Debug,
              ("MediaShutdownManager::BlockShutdown() start..."));

  // Set this flag to ensure no Register() is allowed when Shutdown() begins.
  sInitPhase = XPCOMShutdownStarted;

  auto oldCount = mDecoders.Count();
  if (oldCount == 0) {
    RemoveBlocker();
    return NS_OK;
  }

  // Iterate over the decoders and shut them down.
  for (const auto& key : mDecoders) {
    key->NotifyXPCOMShutdown();
    // Check MediaDecoder::Shutdown doesn't call Unregister() synchronously in
    // order not to corrupt our hashtable traversal.
    MOZ_ASSERT(mDecoders.Count() == oldCount);
  }

  return NS_OK;
}

}  // namespace mozilla

// avoid redefined macro in unified build
#undef LOGW