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Unified Diff: base/task_scheduler/thread_pool.h

Issue 1708773002: TaskScheduler [7] SchedulerThreadPool (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@s_5_worker_thread
Patch Set: self review Created 4 years, 9 months ago
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Index: base/task_scheduler/thread_pool.h
diff --git a/base/task_scheduler/thread_pool.h b/base/task_scheduler/thread_pool.h
new file mode 100644
index 0000000000000000000000000000000000000000..b4ae5b386ae323e41b79bdd889c28ea81dd24d83
--- /dev/null
+++ b/base/task_scheduler/thread_pool.h
@@ -0,0 +1,131 @@
+// 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.
+
+#ifndef BASE_TASK_SCHEDULER_THREAD_POOL_H_
+#define BASE_TASK_SCHEDULER_THREAD_POOL_H_
+
+#include <stddef.h>
+
+#include <stack>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/task_runner.h"
+#include "base/task_scheduler/priority_queue.h"
+#include "base/task_scheduler/scheduler_lock.h"
+#include "base/task_scheduler/scheduler_worker_thread.h"
+#include "base/task_scheduler/sequence.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/threading/platform_thread.h"
+#include "base/threading/thread_local.h"
+
+namespace base {
+namespace internal {
+
+struct SequenceSortKey;
+class TaskTracker;
+
+// A pool of threads that run Tasks. This class is thread-safe.
+class BASE_EXPORT ThreadPool {
+ public:
+ // Creates a ThreadPool with |num_threads| threads of priority
+ // |thread_priority|. |ran_task_from_sequence_callback| is invoked after a
+ // thread of this ThreadPool tries to run a Task from a Sequence.
+ // |task_tracker| is used to handle shutdown behavior of Tasks. Returns
+ // nullptr if when it fails to create a ThreadPool with at least one thread.
+ static scoped_ptr<ThreadPool> CreateThreadPool(
+ ThreadPriority thread_priority,
+ size_t num_threads,
+ const SchedulerWorkerThread::RanTaskFromSequenceCallback&
+ ran_task_from_sequence_callback,
+ TaskTracker* task_tracker);
+
+ // Destroying a ThreadPool in production is not allowed; it is always leaked.
+ // In tests, it can only be destroyed after JoinForTesting() has returned.
+ ~ThreadPool();
+
+ // Returns a TaskRunner whose PostTask invocations will result in scheduling
+ // Tasks with |traits| and |execution_mode| in this ThreadPool.
+ scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits(
+ const TaskTraits& traits,
+ ExecutionMode execution_mode);
+
+ // Reinserts |sequence| in |shared_priority_queue_| with |sequence_sort_key|
+ // after |worker_thread| has run a Task from it. Note that |worker_thread|
robliao 2016/03/31 22:48:56 The second part of this is an implementation detai
fdoray 2016/04/01 16:02:52 Done.
robliao 2016/04/01 19:14:49 Looking at the code side-by-side, do we need worke
fdoray 2016/04/01 20:16:45 Removed it.
+ // doesn't necessarily belong to this ThreadPool.
+ void ReinsertSequence(const SchedulerWorkerThread* worker_thread,
+ scoped_refptr<Sequence> sequence,
+ const SequenceSortKey& sequence_sort_key);
+
+ // Waits until all threads are idle.
+ void WaitForAllWorkerThreadsIdleForTesting();
+
+ // Joins all threads of this ThreadPool. Tasks that are already running are
+ // allowed to complete their execution. This can only be called once.
+ void JoinForTesting();
+
+ private:
+ ThreadPool(ThreadPriority thread_priority,
+ size_t num_threads,
+ const SchedulerWorkerThread::RanTaskFromSequenceCallback&
+ ran_task_from_sequence_callback,
+ TaskTracker* task_tracker);
+
+ // Wakes up one thread from this ThreadPool if they aren't all busy.
+ void WakeUpOneThread();
+
+ // Adds |worker_thread| to |idle_worker_threads_stack_|.
+ void AddToIdleSchedulerWorkerThreadsStack(
+ SchedulerWorkerThread* worker_thread);
+
+ // Invoked when a sequence is inserted in |shared_priority_queue_|.
+ void SequenceInsertedInSharedPriorityQueueCallback();
+
+ // Invoked when the main function of a worker thread is entered.
+ void MainEntryCallback() const;
+
+ // Invoked by a worker thread to get a Sequence from which to run a Task.
+ scoped_refptr<Sequence> GetWorkCallback(SchedulerWorkerThread* worker_thread);
+
+ // PriorityQueue from which all threads of this ThreadPool get work.
+ PriorityQueue shared_priority_queue_;
+
+ // All worker threads owned by this ThreadPool. This is only modified by the
+ // constructor.
+ std::vector<scoped_ptr<SchedulerWorkerThread>> worker_threads_;
+
+ // True if WakeUpOneThread() shouldn't be called when a Sequence is inserted
+ // in |shared_priority_queue_| by a given thread.
+ ThreadLocalBoolean no_wake_up_on_sequence_insertion_;
+
+ // Synchronizes access to |idle_worker_threads_stack_| and
+ // |idle_worker_threads_cv_|.
+ SchedulerLock idle_worker_threads_stack_lock_;
+
+ // Stack of idle worker threads. The last worker thread that became idle is on
+ // top of the stack.
+ std::stack<SchedulerWorkerThread*> idle_worker_threads_stack_;
+
+ // Signaled when all worker threads become idle.
+ scoped_ptr<ConditionVariable> idle_worker_threads_stack_cv_;
+
+ // Synchronizes access to |join_for_testing_returned_|.
+ SchedulerLock join_for_testing_returned_lock_;
+
+ // True once JoinForTesting() has returned.
+ bool join_for_testing_returned_ = false;
+
+ TaskTracker* const task_tracker_;
+
+ DISALLOW_COPY_AND_ASSIGN(ThreadPool);
+};
+
+} // namespace internal
+} // namespace base
+
+#endif // BASE_TASK_SCHEDULER_THREAD_POOL_H_

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