| /* |
| * Copyright 2016 The WebRTC Project Authors. All rights reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #include "webrtc/rtc_base/task_queue.h" |
| |
| #include <mmsystem.h> |
| #include <string.h> |
| |
| #include <algorithm> |
| #include <queue> |
| |
| #include "webrtc/rtc_base/arraysize.h" |
| #include "webrtc/rtc_base/checks.h" |
| #include "webrtc/rtc_base/logging.h" |
| #include "webrtc/rtc_base/safe_conversions.h" |
| #include "webrtc/rtc_base/timeutils.h" |
| |
| namespace rtc { |
| namespace { |
| #define WM_RUN_TASK WM_USER + 1 |
| #define WM_QUEUE_DELAYED_TASK WM_USER + 2 |
| |
| using Priority = TaskQueue::Priority; |
| |
| DWORD g_queue_ptr_tls = 0; |
| |
| BOOL CALLBACK InitializeTls(PINIT_ONCE init_once, void* param, void** context) { |
| g_queue_ptr_tls = TlsAlloc(); |
| return TRUE; |
| } |
| |
| DWORD GetQueuePtrTls() { |
| static INIT_ONCE init_once = INIT_ONCE_STATIC_INIT; |
| ::InitOnceExecuteOnce(&init_once, InitializeTls, nullptr, nullptr); |
| return g_queue_ptr_tls; |
| } |
| |
| struct ThreadStartupData { |
| Event* started; |
| void* thread_context; |
| }; |
| |
| void CALLBACK InitializeQueueThread(ULONG_PTR param) { |
| MSG msg; |
| ::PeekMessage(&msg, nullptr, WM_USER, WM_USER, PM_NOREMOVE); |
| ThreadStartupData* data = reinterpret_cast<ThreadStartupData*>(param); |
| ::TlsSetValue(GetQueuePtrTls(), data->thread_context); |
| data->started->Set(); |
| } |
| |
| ThreadPriority TaskQueuePriorityToThreadPriority(Priority priority) { |
| switch (priority) { |
| case Priority::HIGH: |
| return kRealtimePriority; |
| case Priority::LOW: |
| return kLowPriority; |
| case Priority::NORMAL: |
| return kNormalPriority; |
| default: |
| RTC_NOTREACHED(); |
| break; |
| } |
| return kNormalPriority; |
| } |
| |
| int64_t GetTick() { |
| static const UINT kPeriod = 1; |
| bool high_res = (timeBeginPeriod(kPeriod) == TIMERR_NOERROR); |
| int64_t ret = TimeMillis(); |
| if (high_res) |
| timeEndPeriod(kPeriod); |
| return ret; |
| } |
| |
| class DelayedTaskInfo { |
| public: |
| // Default ctor needed to support priority_queue::pop(). |
| DelayedTaskInfo() {} |
| DelayedTaskInfo(uint32_t milliseconds, std::unique_ptr<QueuedTask> task) |
| : due_time_(GetTick() + milliseconds), task_(std::move(task)) {} |
| DelayedTaskInfo(DelayedTaskInfo&&) = default; |
| |
| // Implement for priority_queue. |
| bool operator>(const DelayedTaskInfo& other) const { |
| return due_time_ > other.due_time_; |
| } |
| |
| // Required by priority_queue::pop(). |
| DelayedTaskInfo& operator=(DelayedTaskInfo&& other) = default; |
| |
| // See below for why this method is const. |
| void Run() const { |
| RTC_DCHECK(due_time_); |
| task_->Run() ? task_.reset() : static_cast<void>(task_.release()); |
| } |
| |
| int64_t due_time() const { return due_time_; } |
| |
| private: |
| int64_t due_time_ = 0; // Absolute timestamp in milliseconds. |
| |
| // |task| needs to be mutable because std::priority_queue::top() returns |
| // a const reference and a key in an ordered queue must not be changed. |
| // There are two basic workarounds, one using const_cast, which would also |
| // make the key (|due_time|), non-const and the other is to make the non-key |
| // (|task|), mutable. |
| // Because of this, the |task| variable is made private and can only be |
| // mutated by calling the |Run()| method. |
| mutable std::unique_ptr<QueuedTask> task_; |
| }; |
| |
| class MultimediaTimer { |
| public: |
| // Note: We create an event that requires manual reset. |
| MultimediaTimer() : event_(::CreateEvent(nullptr, true, false, nullptr)) {} |
| |
| ~MultimediaTimer() { |
| Cancel(); |
| ::CloseHandle(event_); |
| } |
| |
| bool StartOneShotTimer(UINT delay_ms) { |
| RTC_DCHECK_EQ(0, timer_id_); |
| RTC_DCHECK(event_ != nullptr); |
| timer_id_ = |
| ::timeSetEvent(delay_ms, 0, reinterpret_cast<LPTIMECALLBACK>(event_), 0, |
| TIME_ONESHOT | TIME_CALLBACK_EVENT_SET); |
| return timer_id_ != 0; |
| } |
| |
| void Cancel() { |
| ::ResetEvent(event_); |
| if (timer_id_) { |
| ::timeKillEvent(timer_id_); |
| timer_id_ = 0; |
| } |
| } |
| |
| HANDLE* event_for_wait() { return &event_; } |
| |
| private: |
| HANDLE event_ = nullptr; |
| MMRESULT timer_id_ = 0; |
| |
| RTC_DISALLOW_COPY_AND_ASSIGN(MultimediaTimer); |
| }; |
| |
| } // namespace |
| |
| class TaskQueue::ThreadState { |
| public: |
| explicit ThreadState(HANDLE in_queue) : in_queue_(in_queue) {} |
| ~ThreadState() {} |
| |
| void RunThreadMain(); |
| |
| private: |
| bool ProcessQueuedMessages(); |
| void RunDueTasks(); |
| void ScheduleNextTimer(); |
| void CancelTimers(); |
| |
| // Since priority_queue<> by defult orders items in terms of |
| // largest->smallest, using std::less<>, and we want smallest->largest, |
| // we would like to use std::greater<> here. Alas it's only available in |
| // C++14 and later, so we roll our own compare template that that relies on |
| // operator<(). |
| template <typename T> |
| struct greater { |
| bool operator()(const T& l, const T& r) { return l > r; } |
| }; |
| |
| MultimediaTimer timer_; |
| std::priority_queue<DelayedTaskInfo, |
| std::vector<DelayedTaskInfo>, |
| greater<DelayedTaskInfo>> |
| timer_tasks_; |
| UINT_PTR timer_id_ = 0; |
| HANDLE in_queue_; |
| }; |
| |
| TaskQueue::TaskQueue(const char* queue_name, Priority priority /*= NORMAL*/) |
| : thread_(&TaskQueue::ThreadMain, |
| this, |
| queue_name, |
| TaskQueuePriorityToThreadPriority(priority)), |
| in_queue_(::CreateEvent(nullptr, true, false, nullptr)) { |
| RTC_DCHECK(queue_name); |
| RTC_DCHECK(in_queue_); |
| thread_.Start(); |
| Event event(false, false); |
| ThreadStartupData startup = {&event, this}; |
| RTC_CHECK(thread_.QueueAPC(&InitializeQueueThread, |
| reinterpret_cast<ULONG_PTR>(&startup))); |
| event.Wait(Event::kForever); |
| } |
| |
| TaskQueue::~TaskQueue() { |
| RTC_DCHECK(!IsCurrent()); |
| while (!::PostThreadMessage(thread_.GetThreadRef(), WM_QUIT, 0, 0)) { |
| RTC_CHECK_EQ(ERROR_NOT_ENOUGH_QUOTA, ::GetLastError()); |
| Sleep(1); |
| } |
| thread_.Stop(); |
| ::CloseHandle(in_queue_); |
| } |
| |
| // static |
| TaskQueue* TaskQueue::Current() { |
| return static_cast<TaskQueue*>(::TlsGetValue(GetQueuePtrTls())); |
| } |
| |
| bool TaskQueue::IsCurrent() const { |
| return IsThreadRefEqual(thread_.GetThreadRef(), CurrentThreadRef()); |
| } |
| |
| void TaskQueue::PostTask(std::unique_ptr<QueuedTask> task) { |
| rtc::CritScope lock(&pending_lock_); |
| pending_.push(std::move(task)); |
| ::SetEvent(in_queue_); |
| } |
| |
| void TaskQueue::PostDelayedTask(std::unique_ptr<QueuedTask> task, |
| uint32_t milliseconds) { |
| if (!milliseconds) { |
| PostTask(std::move(task)); |
| return; |
| } |
| |
| // TODO(tommi): Avoid this allocation. It is currently here since |
| // the timestamp stored in the task info object, is a 64bit timestamp |
| // and WPARAM is 32bits in 32bit builds. Otherwise, we could pass the |
| // task pointer and timestamp as LPARAM and WPARAM. |
| auto* task_info = new DelayedTaskInfo(milliseconds, std::move(task)); |
| if (!::PostThreadMessage(thread_.GetThreadRef(), WM_QUEUE_DELAYED_TASK, 0, |
| reinterpret_cast<LPARAM>(task_info))) { |
| delete task_info; |
| } |
| } |
| |
| void TaskQueue::PostTaskAndReply(std::unique_ptr<QueuedTask> task, |
| std::unique_ptr<QueuedTask> reply, |
| TaskQueue* reply_queue) { |
| QueuedTask* task_ptr = task.release(); |
| QueuedTask* reply_task_ptr = reply.release(); |
| DWORD reply_thread_id = reply_queue->thread_.GetThreadRef(); |
| PostTask([task_ptr, reply_task_ptr, reply_thread_id]() { |
| if (task_ptr->Run()) |
| delete task_ptr; |
| // If the thread's message queue is full, we can't queue the task and will |
| // have to drop it (i.e. delete). |
| if (!::PostThreadMessage(reply_thread_id, WM_RUN_TASK, 0, |
| reinterpret_cast<LPARAM>(reply_task_ptr))) { |
| delete reply_task_ptr; |
| } |
| }); |
| } |
| |
| void TaskQueue::PostTaskAndReply(std::unique_ptr<QueuedTask> task, |
| std::unique_ptr<QueuedTask> reply) { |
| return PostTaskAndReply(std::move(task), std::move(reply), Current()); |
| } |
| |
| void TaskQueue::RunPendingTasks() { |
| while (true) { |
| std::unique_ptr<QueuedTask> task; |
| { |
| rtc::CritScope lock(&pending_lock_); |
| if (pending_.empty()) |
| break; |
| task = std::move(pending_.front()); |
| pending_.pop(); |
| } |
| |
| if (!task->Run()) |
| task.release(); |
| } |
| } |
| |
| // static |
| void TaskQueue::ThreadMain(void* context) { |
| ThreadState state(static_cast<TaskQueue*>(context)->in_queue_); |
| state.RunThreadMain(); |
| } |
| |
| void TaskQueue::ThreadState::RunThreadMain() { |
| HANDLE handles[2] = { *timer_.event_for_wait(), in_queue_ }; |
| while (true) { |
| // Make sure we do an alertable wait as that's required to allow APCs to run |
| // (e.g. required for InitializeQueueThread and stopping the thread in |
| // PlatformThread). |
| DWORD result = ::MsgWaitForMultipleObjectsEx( |
| arraysize(handles), handles, INFINITE, QS_ALLEVENTS, MWMO_ALERTABLE); |
| RTC_CHECK_NE(WAIT_FAILED, result); |
| if (result == (WAIT_OBJECT_0 + 2)) { |
| // There are messages in the message queue that need to be handled. |
| if (!ProcessQueuedMessages()) |
| break; |
| } |
| |
| if (result == WAIT_OBJECT_0 || (!timer_tasks_.empty() && |
| ::WaitForSingleObject(*timer_.event_for_wait(), 0) == WAIT_OBJECT_0)) { |
| // The multimedia timer was signaled. |
| timer_.Cancel(); |
| RunDueTasks(); |
| ScheduleNextTimer(); |
| } |
| |
| if (result == (WAIT_OBJECT_0 + 1)) { |
| ::ResetEvent(in_queue_); |
| TaskQueue::Current()->RunPendingTasks(); |
| } |
| } |
| } |
| |
| bool TaskQueue::ThreadState::ProcessQueuedMessages() { |
| MSG msg = {}; |
| // To protect against overly busy message queues, we limit the time |
| // we process tasks to a few milliseconds. If we don't do that, there's |
| // a chance that timer tasks won't ever run. |
| static const int kMaxTaskProcessingTimeMs = 500; |
| auto start = GetTick(); |
| while (::PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE) && |
| msg.message != WM_QUIT) { |
| if (!msg.hwnd) { |
| switch (msg.message) { |
| // TODO(tommi): Stop using this way of queueing tasks. |
| case WM_RUN_TASK: { |
| QueuedTask* task = reinterpret_cast<QueuedTask*>(msg.lParam); |
| if (task->Run()) |
| delete task; |
| break; |
| } |
| case WM_QUEUE_DELAYED_TASK: { |
| std::unique_ptr<DelayedTaskInfo> info( |
| reinterpret_cast<DelayedTaskInfo*>(msg.lParam)); |
| bool need_to_schedule_timers = |
| timer_tasks_.empty() || |
| timer_tasks_.top().due_time() > info->due_time(); |
| timer_tasks_.emplace(std::move(*info.get())); |
| if (need_to_schedule_timers) { |
| CancelTimers(); |
| ScheduleNextTimer(); |
| } |
| break; |
| } |
| case WM_TIMER: { |
| RTC_DCHECK_EQ(timer_id_, msg.wParam); |
| ::KillTimer(nullptr, msg.wParam); |
| timer_id_ = 0; |
| RunDueTasks(); |
| ScheduleNextTimer(); |
| break; |
| } |
| default: |
| RTC_NOTREACHED(); |
| break; |
| } |
| } else { |
| ::TranslateMessage(&msg); |
| ::DispatchMessage(&msg); |
| } |
| |
| if (GetTick() > start + kMaxTaskProcessingTimeMs) |
| break; |
| } |
| return msg.message != WM_QUIT; |
| } |
| |
| void TaskQueue::ThreadState::RunDueTasks() { |
| RTC_DCHECK(!timer_tasks_.empty()); |
| auto now = GetTick(); |
| do { |
| const auto& top = timer_tasks_.top(); |
| if (top.due_time() > now) |
| break; |
| top.Run(); |
| timer_tasks_.pop(); |
| } while (!timer_tasks_.empty()); |
| } |
| |
| void TaskQueue::ThreadState::ScheduleNextTimer() { |
| RTC_DCHECK_EQ(timer_id_, 0); |
| if (timer_tasks_.empty()) |
| return; |
| |
| const auto& next_task = timer_tasks_.top(); |
| int64_t delay_ms = std::max(0ll, next_task.due_time() - GetTick()); |
| uint32_t milliseconds = rtc::dchecked_cast<uint32_t>(delay_ms); |
| if (!timer_.StartOneShotTimer(milliseconds)) |
| timer_id_ = ::SetTimer(nullptr, 0, milliseconds, nullptr); |
| } |
| |
| void TaskQueue::ThreadState::CancelTimers() { |
| timer_.Cancel(); |
| if (timer_id_) { |
| ::KillTimer(nullptr, timer_id_); |
| timer_id_ = 0; |
| } |
| } |
| |
| } // namespace rtc |