The Tor Browser / file comparison
comparison: content/media/MediaTaskQueue.cpp
content/media/MediaTaskQueue.cpp
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
equal
deleted
inserted
replaced
| -1:000000000000 | 0:de1625857ae2 |
|---|---|
| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ | |
| 3 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #include "MediaTaskQueue.h" | |
| 8 #include "nsThreadUtils.h" | |
| 9 #include "SharedThreadPool.h" | |
| 10 | |
| 11 namespace mozilla { | |
| 12 | |
| 13 MediaTaskQueue::MediaTaskQueue(TemporaryRef<SharedThreadPool> aPool) | |
| 14 : mPool(aPool) | |
| 15 , mQueueMonitor("MediaTaskQueue::Queue") | |
| 16 , mIsRunning(false) | |
| 17 , mIsShutdown(false) | |
| 18 { | |
| 19 MOZ_COUNT_CTOR(MediaTaskQueue); | |
| 20 } | |
| 21 | |
| 22 MediaTaskQueue::~MediaTaskQueue() | |
| 23 { | |
| 24 MonitorAutoLock mon(mQueueMonitor); | |
| 25 MOZ_ASSERT(mIsShutdown); | |
| 26 MOZ_COUNT_DTOR(MediaTaskQueue); | |
| 27 } | |
| 28 | |
| 29 nsresult | |
| 30 MediaTaskQueue::Dispatch(TemporaryRef<nsIRunnable> aRunnable) | |
| 31 { | |
| 32 MonitorAutoLock mon(mQueueMonitor); | |
| 33 if (mIsShutdown) { | |
| 34 return NS_ERROR_FAILURE; | |
| 35 } | |
| 36 mTasks.push(aRunnable); | |
| 37 if (mIsRunning) { | |
| 38 return NS_OK; | |
| 39 } | |
| 40 RefPtr<nsIRunnable> runner(new Runner(this)); | |
| 41 nsresult rv = mPool->Dispatch(runner, NS_DISPATCH_NORMAL); | |
| 42 if (NS_FAILED(rv)) { | |
| 43 NS_WARNING("Failed to dispatch runnable to run MediaTaskQueue"); | |
| 44 return rv; | |
| 45 } | |
| 46 mIsRunning = true; | |
| 47 | |
| 48 return NS_OK; | |
| 49 } | |
| 50 | |
| 51 void | |
| 52 MediaTaskQueue::AwaitIdle() | |
| 53 { | |
| 54 MonitorAutoLock mon(mQueueMonitor); | |
| 55 AwaitIdleLocked(); | |
| 56 } | |
| 57 | |
| 58 void | |
| 59 MediaTaskQueue::AwaitIdleLocked() | |
| 60 { | |
| 61 mQueueMonitor.AssertCurrentThreadOwns(); | |
| 62 MOZ_ASSERT(mIsRunning || mTasks.empty()); | |
| 63 while (mIsRunning) { | |
| 64 mQueueMonitor.Wait(); | |
| 65 } | |
| 66 } | |
| 67 | |
| 68 void | |
| 69 MediaTaskQueue::Shutdown() | |
| 70 { | |
| 71 MonitorAutoLock mon(mQueueMonitor); | |
| 72 mIsShutdown = true; | |
| 73 AwaitIdleLocked(); | |
| 74 } | |
| 75 | |
| 76 void | |
| 77 MediaTaskQueue::Flush() | |
| 78 { | |
| 79 MonitorAutoLock mon(mQueueMonitor); | |
| 80 while (!mTasks.empty()) { | |
| 81 mTasks.pop(); | |
| 82 } | |
| 83 AwaitIdleLocked(); | |
| 84 } | |
| 85 | |
| 86 bool | |
| 87 MediaTaskQueue::IsEmpty() | |
| 88 { | |
| 89 MonitorAutoLock mon(mQueueMonitor); | |
| 90 return mTasks.empty(); | |
| 91 } | |
| 92 | |
| 93 bool | |
| 94 MediaTaskQueue::IsCurrentThreadIn() | |
| 95 { | |
| 96 #ifdef DEBUG | |
| 97 MonitorAutoLock mon(mQueueMonitor); | |
| 98 return NS_GetCurrentThread() == mRunningThread; | |
| 99 #else | |
| 100 return false; | |
| 101 #endif | |
| 102 } | |
| 103 | |
| 104 nsresult | |
| 105 MediaTaskQueue::Runner::Run() | |
| 106 { | |
| 107 RefPtr<nsIRunnable> event; | |
| 108 { | |
| 109 MonitorAutoLock mon(mQueue->mQueueMonitor); | |
| 110 MOZ_ASSERT(mQueue->mIsRunning); | |
| 111 mQueue->mRunningThread = NS_GetCurrentThread(); | |
| 112 if (mQueue->mTasks.size() == 0) { | |
| 113 mQueue->mIsRunning = false; | |
| 114 mon.NotifyAll(); | |
| 115 return NS_OK; | |
| 116 } | |
| 117 event = mQueue->mTasks.front(); | |
| 118 mQueue->mTasks.pop(); | |
| 119 } | |
| 120 MOZ_ASSERT(event); | |
| 121 | |
| 122 // Note that dropping the queue monitor before running the task, and | |
| 123 // taking the monitor again after the task has run ensures we have memory | |
| 124 // fences enforced. This means that if the object we're calling wasn't | |
| 125 // designed to be threadsafe, it will be, provided we're only calling it | |
| 126 // in this task queue. | |
| 127 event->Run(); | |
| 128 | |
| 129 // Drop the reference to event. The event will hold a reference to the | |
| 130 // object it's calling, and we don't want to keep it alive, it may be | |
| 131 // making assumptions what holds references to it. This is especially | |
| 132 // the case if the object is waiting for us to shutdown, so that it | |
| 133 // can shutdown (like in the MediaDecoderStateMachine's SHUTDOWN case). | |
| 134 event = nullptr; | |
| 135 | |
| 136 { | |
| 137 MonitorAutoLock mon(mQueue->mQueueMonitor); | |
| 138 if (mQueue->mTasks.size() == 0) { | |
| 139 // No more events to run. Exit the task runner. | |
| 140 mQueue->mIsRunning = false; | |
| 141 mon.NotifyAll(); | |
| 142 mQueue->mRunningThread = nullptr; | |
| 143 return NS_OK; | |
| 144 } | |
| 145 } | |
| 146 | |
| 147 // There's at least one more event that we can run. Dispatch this Runner | |
| 148 // to the thread pool again to ensure it runs again. Note that we don't just | |
| 149 // run in a loop here so that we don't hog the thread pool. This means we may | |
| 150 // run on another thread next time, but we rely on the memory fences from | |
| 151 // mQueueMonitor for thread safety of non-threadsafe tasks. | |
| 152 { | |
| 153 MonitorAutoLock mon(mQueue->mQueueMonitor); | |
| 154 // Note: Hold the monitor *before* we dispatch, in case we context switch | |
| 155 // to another thread pool in the queue immediately and take the lock in the | |
| 156 // other thread; mRunningThread could be set to the new thread's value and | |
| 157 // then incorrectly anulled below in that case. | |
| 158 nsresult rv = mQueue->mPool->Dispatch(this, NS_DISPATCH_NORMAL); | |
| 159 if (NS_FAILED(rv)) { | |
| 160 // Failed to dispatch, shutdown! | |
| 161 mQueue->mIsRunning = false; | |
| 162 mQueue->mIsShutdown = true; | |
| 163 mon.NotifyAll(); | |
| 164 } | |
| 165 mQueue->mRunningThread = nullptr; | |
| 166 } | |
| 167 | |
| 168 return NS_OK; | |
| 169 } | |
| 170 | |
| 171 } // namespace mozilla |
