Index: base/task_scheduler/thread_pool.cc |
diff --git a/base/task_scheduler/thread_pool.cc b/base/task_scheduler/thread_pool.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..55f17baaa4fc59ecbe3a3dd64b9db012ff4df86e |
--- /dev/null |
+++ b/base/task_scheduler/thread_pool.cc |
@@ -0,0 +1,253 @@ |
+// Copyright 2016 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "base/task_scheduler/thread_pool.h" |
+ |
+#include <utility> |
+ |
+#include "base/bind.h" |
+#include "base/bind_helpers.h" |
+#include "base/lazy_instance.h" |
+#include "base/logging.h" |
+#include "base/task_scheduler/task_tracker.h" |
+ |
+namespace base { |
+namespace internal { |
+ |
+namespace { |
+ |
+// Shared PriorityQueue of a thread's ThreadPool. Not set for threads that don't |
+// belong to a ThreadPool. |
+LazyInstance<ThreadLocalPointer<const PriorityQueue>>::Leaky |
+ g_current_shared_priority_queue = LAZY_INSTANCE_INITIALIZER; |
+ |
+void PostTaskCallback(scoped_refptr<Sequence> sequence, |
robliao
2016/03/31 22:48:56
Wasn't this and the below going to go into utils.h
fdoray
2016/04/01 16:02:51
Yes, it was previously in utils.h|.cc because it w
robliao
2016/04/01 19:14:49
Given that PostTaskHelper is somewhat like a priva
fdoray
2016/04/01 20:16:45
PostTaskHelper is only one statement, but it indir
|
+ PriorityQueue* priority_queue, |
+ scoped_ptr<Task> task) { |
robliao
2016/03/31 22:48:55
Should DCHECK(task) as it's not immediately derefe
fdoray
2016/04/01 16:02:51
Done. DCHECK everything to be consistent.
|
+ if (sequence->PushTask(std::move(task))) { |
+ // |sequence| must be inserted into |priority_queue| because it was empty |
+ // before |task| was inserted into it. |
+ const SequenceSortKey sequence_sort_key = sequence->GetSortKey(); |
+ priority_queue->BeginTransaction()->Push( |
+ make_scoped_ptr(new PriorityQueue::SequenceAndSortKey( |
+ std::move(sequence), sequence_sort_key))); |
+ } |
+} |
+ |
+// Helper for posting |task| to the provided |sequence| and |priority_queue| |
+// conditional on |task_tracker|. Used by all TaskRunners defined in this file. |
+void PostTaskHelper(scoped_ptr<Task> task, |
+ scoped_refptr<Sequence> sequence, |
robliao
2016/03/31 22:48:55
sequence, priority_queue, and task should be DCHEC
fdoray
2016/04/01 16:02:52
Done.
|
+ PriorityQueue* priority_queue, |
+ TaskTracker* task_tracker) { |
+ task_tracker->PostTask( |
+ Bind(&PostTaskCallback, std::move(sequence), priority_queue), |
+ std::move(task)); |
+} |
+ |
+// A task runner that runs tasks with the PARALLEL ExecutionMode. |
+class SchedulerParallelTaskRunner : public TaskRunner { |
+ public: |
+ SchedulerParallelTaskRunner(const TaskTraits& traits, |
+ PriorityQueue* priority_queue, |
+ TaskTracker* task_tracker) |
+ : traits_(traits), |
+ priority_queue_(priority_queue), |
+ task_tracker_(task_tracker) {} |
+ |
+ // TaskRunner: |
+ bool PostDelayedTask(const tracked_objects::Location& from_here, |
+ const Closure& closure, |
+ TimeDelta delay) override { |
+ // TODO(fdoray): Support delayed tasks. |
+ DCHECK(delay.is_zero()); |
+ PostTaskHelper(make_scoped_ptr(new Task(from_here, closure, traits_)), |
+ make_scoped_refptr(new Sequence), priority_queue_, |
+ task_tracker_); |
+ return true; |
+ } |
+ |
+ bool RunsTasksOnCurrentThread() const override { |
+ return g_current_shared_priority_queue.Get().Get() == priority_queue_; |
+ } |
+ |
+ private: |
+ ~SchedulerParallelTaskRunner() override = default; |
+ |
+ const TaskTraits traits_; |
+ PriorityQueue* const priority_queue_; |
+ TaskTracker* const task_tracker_; |
+ |
+ DISALLOW_COPY_AND_ASSIGN(SchedulerParallelTaskRunner); |
+}; |
+ |
+} // namespace |
+ |
+ThreadPool::~ThreadPool() { |
+ AutoSchedulerLock auto_lock(join_for_testing_returned_lock_); |
+ DCHECK(join_for_testing_returned_); |
+} |
+ |
+scoped_ptr<ThreadPool> ThreadPool::CreateThreadPool( |
+ ThreadPriority thread_priority, |
+ size_t num_threads, |
+ const SchedulerWorkerThread::RanTaskFromSequenceCallback& |
+ ran_task_from_sequence_callback, |
+ TaskTracker* task_tracker) { |
+ scoped_ptr<ThreadPool> thread_pool( |
+ new ThreadPool(thread_priority, num_threads, |
+ ran_task_from_sequence_callback, task_tracker)); |
+ |
+ if (thread_pool->worker_threads_.empty()) |
robliao
2016/03/31 22:48:56
Does checking the thread count == num_threads make
fdoray
2016/04/01 16:02:51
gab@ said that we should return a ThreadPool w/o e
robliao
2016/04/01 19:14:49
A histogram would make sense if we were able to ta
fdoray
2016/04/01 20:16:45
Done. Renamed num_threads -> max_threads.
I think
|
+ return nullptr; |
+ return thread_pool; |
+} |
+ |
+scoped_refptr<TaskRunner> ThreadPool::CreateTaskRunnerWithTraits( |
+ const TaskTraits& traits, |
+ ExecutionMode execution_mode) { |
+ switch (execution_mode) { |
+ case ExecutionMode::PARALLEL: |
+ return make_scoped_refptr(new SchedulerParallelTaskRunner( |
+ traits, &shared_priority_queue_, task_tracker_)); |
+ |
+ case ExecutionMode::SEQUENCED: |
+ case ExecutionMode::SINGLE_THREADED: |
+ NOTIMPLEMENTED(); |
+ return nullptr; |
+ } |
+} |
+ |
+void ThreadPool::ReinsertSequence(const SchedulerWorkerThread* worker_thread, |
+ scoped_refptr<Sequence> sequence, |
+ const SequenceSortKey& sequence_sort_key) { |
+ DCHECK(!g_current_shared_priority_queue.Get().Get()); |
+ |
+ // If |worker_thread| belongs to this ThreadPool, set a flag to avoid waking |
+ // up a SchedulerWorkerThread when |sequence| is reinserted in |
+ // |shared_priority_queue_|. In such cases, |worker_thread| will soon pop a |
+ // Sequence from |shared_priority_queue_| which means that there is no need to |
+ // wake up another SchedulerWorkerThread to do so. |
robliao
2016/03/31 22:48:56
Update this comment with the delegated GetWork.
fdoray
2016/04/01 16:02:51
Done.
|
+ if (g_current_shared_priority_queue.Get().Get() == &shared_priority_queue_) |
+ no_wake_up_on_sequence_insertion_.Set(true); |
+ |
+ shared_priority_queue_.BeginTransaction()->Push( |
+ make_scoped_ptr(new PriorityQueue::SequenceAndSortKey( |
+ std::move(sequence), sequence_sort_key))); |
+ no_wake_up_on_sequence_insertion_.Set(false); |
+} |
+ |
+void ThreadPool::WaitForAllWorkerThreadsIdleForTesting() { |
+ AutoSchedulerLock auto_lock(idle_worker_threads_stack_lock_); |
+ while (idle_worker_threads_stack_.size() < worker_threads_.size()) |
+ idle_worker_threads_stack_cv_->Wait(); |
+} |
+ |
+void ThreadPool::JoinForTesting() { |
+ for (const auto& worker_thread : worker_threads_) |
+ worker_thread->JoinForTesting(); |
+ |
+ { |
robliao
2016/03/31 22:48:55
Is this scope necessary?
fdoray
2016/04/01 16:02:52
No. Removed it.
|
+ AutoSchedulerLock auto_lock(join_for_testing_returned_lock_); |
+ DCHECK(!join_for_testing_returned_); |
+ join_for_testing_returned_ = true; |
+ } |
+} |
+ |
+ThreadPool::ThreadPool(ThreadPriority thread_priority, |
+ size_t num_threads, |
+ const SchedulerWorkerThread::RanTaskFromSequenceCallback& |
+ ran_task_from_sequence_callback, |
+ TaskTracker* task_tracker) |
+ : shared_priority_queue_( |
+ Bind(&ThreadPool::SequenceInsertedInSharedPriorityQueueCallback, |
+ Unretained(this))), |
+ idle_worker_threads_stack_lock_(shared_priority_queue_.container_lock()), |
+ idle_worker_threads_stack_cv_( |
+ idle_worker_threads_stack_lock_.CreateConditionVariable()), |
+ task_tracker_(task_tracker) { |
+ DCHECK_GT(num_threads, 0U); |
+ DCHECK(!ran_task_from_sequence_callback.is_null()); |
+ DCHECK(task_tracker_); |
+ |
+ // |this| always outlives the worker threads to which these callbacks are |
+ // passed. |
+ const Closure main_entry_callback( |
+ Bind(&ThreadPool::MainEntryCallback, Unretained(this))); |
+ const SchedulerWorkerThread::GetWorkCallback get_work_callback( |
+ Bind(&ThreadPool::GetWorkCallback, Unretained(this))); |
+ |
+ AutoSchedulerLock auto_lock(idle_worker_threads_stack_lock_); |
+ |
+ for (size_t i = 0; i < num_threads; ++i) { |
+ scoped_ptr<SchedulerWorkerThread> worker_thread = |
+ SchedulerWorkerThread::CreateSchedulerWorkerThread( |
+ thread_priority, main_entry_callback, get_work_callback, |
+ ran_task_from_sequence_callback, task_tracker); |
+ if (worker_thread) { |
robliao
2016/03/31 22:48:55
If we decide to fail when we couldn't create all t
fdoray
2016/04/01 16:02:52
I think it makes sense to fail-fast because it is
|
+ idle_worker_threads_stack_.push(worker_thread.get()); |
+ worker_threads_.push_back(std::move(worker_thread)); |
+ } |
+ } |
+} |
+ |
+void ThreadPool::WakeUpOneThread() { |
+ AutoSchedulerLock auto_lock(idle_worker_threads_stack_lock_); |
+ |
+ if (idle_worker_threads_stack_.empty()) |
+ return; |
+ |
+ idle_worker_threads_stack_.top()->WakeUp(); |
robliao
2016/03/31 22:48:56
Optional: It might be more robust to wake up the t
fdoray
2016/04/01 16:02:51
Done. I don't like the fact that it requires one m
|
+ idle_worker_threads_stack_.pop(); |
+} |
+ |
+void ThreadPool::AddToIdleSchedulerWorkerThreadsStack( |
+ SchedulerWorkerThread* worker_thread) { |
+ AutoSchedulerLock auto_lock(idle_worker_threads_stack_lock_); |
+ idle_worker_threads_stack_.push(worker_thread); |
+ DCHECK_LE(idle_worker_threads_stack_.size(), worker_threads_.size()); |
+ |
+ if (idle_worker_threads_stack_.size() == worker_threads_.size()) |
+ idle_worker_threads_stack_cv_->Signal(); |
+} |
+ |
+void ThreadPool::SequenceInsertedInSharedPriorityQueueCallback() { |
+ if (!no_wake_up_on_sequence_insertion_.Get()) |
+ WakeUpOneThread(); |
+} |
+ |
+void ThreadPool::MainEntryCallback() const { |
+ DCHECK(!g_current_shared_priority_queue.Get().Get()); |
+ g_current_shared_priority_queue.Get().Set(&shared_priority_queue_); |
+} |
+ |
+scoped_refptr<Sequence> ThreadPool::GetWorkCallback( |
+ SchedulerWorkerThread* worker_thread) { |
+ scoped_ptr<PriorityQueue::Transaction> transaction( |
+ shared_priority_queue_.BeginTransaction()); |
+ const PriorityQueue::SequenceAndSortKey sequence_and_sort_key( |
+ transaction->Peek()); |
+ |
+ if (sequence_and_sort_key.is_null()) { |
+ // |transaction| is kept alive while |worker_thread| is added to |
+ // |idle_worker_threads_stack_| to avoid this scenario: |
robliao
2016/03/31 22:48:55
Nit: scenario -> race
fdoray
2016/04/01 16:02:52
Done.
|
+ // 1. This thread creates a Transaction, finds |shared_priority_queue_| |
+ // empty and ends the Transaction. |
+ // 2. Other thread creates a Transaction, inserts a Sequence into |
+ // |shared_priority_queue_| and ends the Transaction. This couldn't |
robliao
2016/03/31 22:48:55
Nit: couldn't -> can't
fdoray
2016/04/01 16:02:51
Done.
|
+ // happen if the Transaction of step 1 was still active. |
+ // 3. Other thread calls WakeUpOneThread(). No thread is woken up because |
+ // |idle_worker_threads_stack_| is empty. |
+ // 4. This thread adds itself to |idle_worker_threads_stack_| and goes to |
+ // sleep. No thread runs the Sequence inserted in step 2. |
+ AddToIdleSchedulerWorkerThreadsStack(worker_thread); |
+ return nullptr; |
+ } |
+ |
+ transaction->Pop(); |
+ return sequence_and_sort_key.sequence; |
+} |
+ |
+} // namespace internal |
+} // namespace base |