gecko-dev/dom/media/MediaShutdownManager.cpp

168 строки
5.3 KiB
C++

/* -*- 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 "nsContentUtils.h"
#include "mozilla/StaticPtr.h"
#include "MediaDecoder.h"
#include "mozilla/Logging.h"
namespace mozilla {
extern LazyLogModule gMediaDecoderLog;
#define DECODER_LOG(type, msg) MOZ_LOG(gMediaDecoderLog, type, msg)
NS_IMPL_ISUPPORTS(MediaShutdownManager, nsIObserver)
MediaShutdownManager::MediaShutdownManager()
: mIsObservingShutdown(false)
, mIsDoingXPCOMShutDown(false)
, mCompletedShutdown(false)
{
MOZ_ASSERT(NS_IsMainThread());
MOZ_COUNT_CTOR(MediaShutdownManager);
}
MediaShutdownManager::~MediaShutdownManager()
{
MOZ_ASSERT(NS_IsMainThread());
MOZ_COUNT_DTOR(MediaShutdownManager);
}
// Note that we don't use ClearOnShutdown() on this StaticRefPtr, as that
// may interfere with our shutdown listener.
StaticRefPtr<MediaShutdownManager> MediaShutdownManager::sInstance;
MediaShutdownManager&
MediaShutdownManager::Instance()
{
MOZ_ASSERT(NS_IsMainThread());
if (!sInstance) {
sInstance = new MediaShutdownManager();
}
return *sInstance;
}
void
MediaShutdownManager::EnsureCorrectShutdownObserverState()
{
MOZ_ASSERT(!mIsDoingXPCOMShutDown);
bool needShutdownObserver = mDecoders.Count() > 0;
if (needShutdownObserver != mIsObservingShutdown) {
mIsObservingShutdown = needShutdownObserver;
if (mIsObservingShutdown) {
nsContentUtils::RegisterShutdownObserver(this);
} else {
nsContentUtils::UnregisterShutdownObserver(this);
// Clear our singleton reference. This will probably delete
// this instance, so don't deref |this| clearing sInstance.
sInstance = nullptr;
}
}
}
void
MediaShutdownManager::Register(MediaDecoder* aDecoder)
{
MOZ_ASSERT(NS_IsMainThread());
// Don't call Register() after you've Unregistered() all the decoders,
// that's not going to work.
MOZ_ASSERT(!mDecoders.Contains(aDecoder));
mDecoders.PutEntry(aDecoder);
MOZ_ASSERT(mDecoders.Contains(aDecoder));
MOZ_ASSERT(mDecoders.Count() > 0);
EnsureCorrectShutdownObserverState();
}
void
MediaShutdownManager::Unregister(MediaDecoder* aDecoder)
{
MOZ_ASSERT(NS_IsMainThread());
MOZ_ASSERT(mDecoders.Contains(aDecoder));
if (!mIsDoingXPCOMShutDown) {
mDecoders.RemoveEntry(aDecoder);
EnsureCorrectShutdownObserverState();
}
}
NS_IMETHODIMP
MediaShutdownManager::Observe(nsISupports *aSubjet,
const char *aTopic,
const char16_t *someData)
{
MOZ_ASSERT(NS_IsMainThread());
if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
Shutdown();
}
return NS_OK;
}
void
MediaShutdownManager::Shutdown()
{
MOZ_ASSERT(NS_IsMainThread());
MOZ_ASSERT(sInstance);
DECODER_LOG(LogLevel::Debug, ("MediaShutdownManager::Shutdown() start..."));
// Mark that we're shutting down, so that Unregister(*) calls don't remove
// hashtable entries. If Unregsiter(*) was to remove from the hash table,
// the iterations over the hashtables below would be disrupted.
mIsDoingXPCOMShutDown = true;
// Iterate over the decoders and shut them down, and remove them from the
// hashtable.
nsTArray<RefPtr<ShutdownPromise>> promises;
for (auto iter = mDecoders.Iter(); !iter.Done(); iter.Next()) {
promises.AppendElement(iter.Get()->GetKey()->Shutdown()->Then(
// We want to ensure that all shutdowns have completed, regardless
// of the ShutdownPromise being resolved or rejected. At this stage,
// a MediaDecoder's ShutdownPromise is only ever resolved, but as this may
// change in the future we want to avoid nasty surprises, so we wrap the
// ShutdownPromise into our own that will only ever be resolved.
AbstractThread::MainThread(), __func__,
[]() -> RefPtr<ShutdownPromise> {
return ShutdownPromise::CreateAndResolve(true, __func__);
},
[]() -> RefPtr<ShutdownPromise> {
return ShutdownPromise::CreateAndResolve(true, __func__);
})->CompletionPromise());
iter.Remove();
}
if (!promises.IsEmpty()) {
ShutdownPromise::All(AbstractThread::MainThread(), promises)
->Then(AbstractThread::MainThread(), __func__, this,
&MediaShutdownManager::FinishShutdown,
&MediaShutdownManager::FinishShutdown);
// Wait for all decoders to complete their async shutdown...
while (!mCompletedShutdown) {
NS_ProcessNextEvent(NS_GetCurrentThread(), true);
}
}
// Remove the MediaShutdownManager instance from the shutdown observer
// list.
nsContentUtils::UnregisterShutdownObserver(this);
// Clear the singleton instance. The only remaining reference should be the
// reference that the observer service used to call us with. The
// MediaShutdownManager will be deleted once the observer service cleans
// up after it finishes its notifications.
sInstance = nullptr;
DECODER_LOG(LogLevel::Debug, ("MediaShutdownManager::Shutdown() end."));
}
void
MediaShutdownManager::FinishShutdown()
{
MOZ_ASSERT(NS_IsMainThread());
mCompletedShutdown = true;
}
} // namespace mozilla