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src: Node implementation of v8::Platform
Node.js currently uses the V8 implementation of the DefaultPlatform which schedules VM tasks on a V8 managed thread pool. Since the Node.js event loop is not aware of these tasks, the Node.js process may exit while there are outstanding VM tasks. This will become problematic once asynchronous wasm compilation lands in V8. This PR introduces a Node.js specific implementation of the v8::Platform on top of libuv so that the event loop is aware of outstanding VM tasks. PR-URL: #14001 Fixes: #3665 Fixes: #8496 Fixes: #12980 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Tobias Nießen <[email protected]>
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Matt Loring
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Aug 17, 2017
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,189 @@ | ||
| #include "node_platform.h" | ||
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| #include "util.h" | ||
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| namespace node { | ||
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| using v8::Isolate; | ||
| using v8::Platform; | ||
| using v8::Task; | ||
| using v8::TracingController; | ||
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| static void FlushTasks(uv_async_t* handle) { | ||
| NodePlatform* platform = static_cast<NodePlatform*>(handle->data); | ||
| platform->FlushForegroundTasksInternal(); | ||
| } | ||
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| static void BackgroundRunner(void* data) { | ||
| TaskQueue<Task>* background_tasks = static_cast<TaskQueue<Task>*>(data); | ||
| while (Task* task = background_tasks->BlockingPop()) { | ||
| task->Run(); | ||
| delete task; | ||
| background_tasks->NotifyOfCompletion(); | ||
| } | ||
| } | ||
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| NodePlatform::NodePlatform(int thread_pool_size, uv_loop_t* loop, | ||
| TracingController* tracing_controller) | ||
| : loop_(loop) { | ||
| CHECK_EQ(0, uv_async_init(loop, &flush_tasks_, FlushTasks)); | ||
| flush_tasks_.data = static_cast<void*>(this); | ||
| uv_unref(reinterpret_cast<uv_handle_t*>(&flush_tasks_)); | ||
| if (tracing_controller) { | ||
| tracing_controller_.reset(tracing_controller); | ||
| } else { | ||
| TracingController* controller = new TracingController(); | ||
| tracing_controller_.reset(controller); | ||
| } | ||
| for (int i = 0; i < thread_pool_size; i++) { | ||
| uv_thread_t* t = new uv_thread_t(); | ||
| if (uv_thread_create(t, BackgroundRunner, &background_tasks_) != 0) { | ||
| delete t; | ||
| break; | ||
| } | ||
| threads_.push_back(std::unique_ptr<uv_thread_t>(t)); | ||
| } | ||
| } | ||
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| void NodePlatform::Shutdown() { | ||
| background_tasks_.Stop(); | ||
| for (size_t i = 0; i < threads_.size(); i++) { | ||
| CHECK_EQ(0, uv_thread_join(threads_[i].get())); | ||
| } | ||
| // uv_run cannot be called from the time before the beforeExit callback | ||
| // runs until the program exits unless the event loop has any referenced | ||
| // handles after beforeExit terminates. This prevents unrefed timers | ||
| // that happen to terminate during shutdown from being run unsafely. | ||
| // Since uv_run cannot be called, this handle will never be fully cleaned | ||
| // up. | ||
| uv_close(reinterpret_cast<uv_handle_t*>(&flush_tasks_), nullptr); | ||
| } | ||
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| size_t NodePlatform::NumberOfAvailableBackgroundThreads() { | ||
| return threads_.size(); | ||
| } | ||
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| static void RunForegroundTask(uv_timer_t* handle) { | ||
| Task* task = static_cast<Task*>(handle->data); | ||
| task->Run(); | ||
| delete task; | ||
| uv_close(reinterpret_cast<uv_handle_t*>(handle), [](uv_handle_t* handle) { | ||
| delete reinterpret_cast<uv_timer_t*>(handle); | ||
| }); | ||
| } | ||
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| void NodePlatform::DrainBackgroundTasks() { | ||
| FlushForegroundTasksInternal(); | ||
| background_tasks_.BlockingDrain(); | ||
| } | ||
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| void NodePlatform::FlushForegroundTasksInternal() { | ||
| while (auto delayed = foreground_delayed_tasks_.Pop()) { | ||
| uint64_t delay_millis = | ||
| static_cast<uint64_t>(delayed->second + 0.5) * 1000; | ||
| uv_timer_t* handle = new uv_timer_t(); | ||
| handle->data = static_cast<void*>(delayed->first); | ||
| uv_timer_init(loop_, handle); | ||
| // Timers may not guarantee queue ordering of events with the same delay if | ||
| // the delay is non-zero. This should not be a problem in practice. | ||
| uv_timer_start(handle, RunForegroundTask, delay_millis, 0); | ||
| uv_unref(reinterpret_cast<uv_handle_t*>(handle)); | ||
| delete delayed; | ||
| } | ||
| while (Task* task = foreground_tasks_.Pop()) { | ||
| task->Run(); | ||
| delete task; | ||
| } | ||
| } | ||
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| void NodePlatform::CallOnBackgroundThread(Task* task, | ||
| ExpectedRuntime expected_runtime) { | ||
| background_tasks_.Push(task); | ||
| } | ||
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| void NodePlatform::CallOnForegroundThread(Isolate* isolate, Task* task) { | ||
| foreground_tasks_.Push(task); | ||
| uv_async_send(&flush_tasks_); | ||
| } | ||
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| void NodePlatform::CallDelayedOnForegroundThread(Isolate* isolate, | ||
| Task* task, | ||
| double delay_in_seconds) { | ||
| auto pair = new std::pair<Task*, double>(task, delay_in_seconds); | ||
| foreground_delayed_tasks_.Push(pair); | ||
| uv_async_send(&flush_tasks_); | ||
| } | ||
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| bool NodePlatform::IdleTasksEnabled(Isolate* isolate) { return false; } | ||
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| double NodePlatform::MonotonicallyIncreasingTime() { | ||
| // Convert nanos to seconds. | ||
| return uv_hrtime() / 1e9; | ||
| } | ||
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| TracingController* NodePlatform::GetTracingController() { | ||
| return tracing_controller_.get(); | ||
| } | ||
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| template <class T> | ||
| TaskQueue<T>::TaskQueue() | ||
| : lock_(), tasks_available_(), tasks_drained_(), | ||
| outstanding_tasks_(0), stopped_(false), task_queue_() { } | ||
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| template <class T> | ||
| void TaskQueue<T>::Push(T* task) { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| outstanding_tasks_++; | ||
| task_queue_.push(task); | ||
| tasks_available_.Signal(scoped_lock); | ||
| } | ||
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| template <class T> | ||
| T* TaskQueue<T>::Pop() { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| T* result = nullptr; | ||
| if (!task_queue_.empty()) { | ||
| result = task_queue_.front(); | ||
| task_queue_.pop(); | ||
| } | ||
| return result; | ||
| } | ||
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| template <class T> | ||
| T* TaskQueue<T>::BlockingPop() { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| while (task_queue_.empty() && !stopped_) { | ||
| tasks_available_.Wait(scoped_lock); | ||
| } | ||
| if (stopped_) { | ||
| return nullptr; | ||
| } | ||
| T* result = task_queue_.front(); | ||
| task_queue_.pop(); | ||
| return result; | ||
| } | ||
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| template <class T> | ||
| void TaskQueue<T>::NotifyOfCompletion() { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| if (--outstanding_tasks_ == 0) { | ||
| tasks_drained_.Broadcast(scoped_lock); | ||
| } | ||
| } | ||
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| template <class T> | ||
| void TaskQueue<T>::BlockingDrain() { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| while (outstanding_tasks_ > 0) { | ||
| tasks_drained_.Wait(scoped_lock); | ||
| } | ||
| } | ||
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| template <class T> | ||
| void TaskQueue<T>::Stop() { | ||
| Mutex::ScopedLock scoped_lock(lock_); | ||
| stopped_ = true; | ||
| tasks_available_.Broadcast(scoped_lock); | ||
| } | ||
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| } // namespace node |
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