217 lines
9.3 KiB
C++
217 lines
9.3 KiB
C++
// Copyright 2016 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TASK_THREAD_POOL_THREAD_POOL_IMPL_H_
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#define BASE_TASK_THREAD_POOL_THREAD_POOL_IMPL_H_
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#include <memory>
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#include "base/base_export.h"
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#include "base/dcheck_is_on.h"
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#include "base/functional/callback.h"
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#include "base/memory/ptr_util.h"
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#include "base/sequence_checker.h"
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#include "base/strings/string_piece.h"
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#include "base/synchronization/atomic_flag.h"
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#include "base/task/single_thread_task_runner_thread_mode.h"
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#include "base/task/task_traits.h"
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#include "base/task/thread_pool/delayed_task_manager.h"
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#include "base/task/thread_pool/environment_config.h"
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#include "base/task/thread_pool/pooled_single_thread_task_runner_manager.h"
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#include "base/task/thread_pool/pooled_task_runner_delegate.h"
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#include "base/task/thread_pool/service_thread.h"
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#include "base/task/thread_pool/task_source.h"
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#include "base/task/thread_pool/task_tracker.h"
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#include "base/task/thread_pool/thread_group.h"
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#include "base/task/thread_pool/thread_group_impl.h"
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#include "base/task/thread_pool/thread_pool_instance.h"
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#include "base/task/updateable_sequenced_task_runner.h"
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#include "base/thread_annotations.h"
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#include "build/build_config.h"
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#include "third_party/abseil-cpp/absl/types/optional.h"
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#if BUILDFLAG(IS_WIN)
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#include "base/win/com_init_check_hook.h"
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#endif
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namespace base {
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namespace internal {
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// Default ThreadPoolInstance implementation. This class is thread-safe, except
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// for methods noted otherwise in thread_pool_instance.h.
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class BASE_EXPORT ThreadPoolImpl : public ThreadPoolInstance,
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public ThreadGroup::Delegate,
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public PooledTaskRunnerDelegate {
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public:
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using TaskTrackerImpl = TaskTracker;
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// Creates a ThreadPoolImpl with a production TaskTracker. |histogram_label|
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// is used to label histograms. No histograms are recorded if it is empty.
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explicit ThreadPoolImpl(StringPiece histogram_label);
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// For testing only. Creates a ThreadPoolImpl with a custom TaskTracker.
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// If |!use_background_threads|, background threads will run with default
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// priority.
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ThreadPoolImpl(StringPiece histogram_label,
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std::unique_ptr<TaskTrackerImpl> task_tracker,
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bool use_background_threads = true);
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ThreadPoolImpl(const ThreadPoolImpl&) = delete;
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ThreadPoolImpl& operator=(const ThreadPoolImpl&) = delete;
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~ThreadPoolImpl() override;
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// ThreadPoolInstance:
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void Start(const ThreadPoolInstance::InitParams& init_params,
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WorkerThreadObserver* worker_thread_observer) override;
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bool WasStarted() const final;
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bool WasStartedUnsafe() const final;
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size_t GetMaxConcurrentNonBlockedTasksWithTraitsDeprecated(
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const TaskTraits& traits) const override;
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void Shutdown() override;
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void FlushForTesting() override;
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void FlushAsyncForTesting(OnceClosure flush_callback) override;
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void JoinForTesting() override;
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void BeginFence() override;
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void EndFence() override;
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void BeginBestEffortFence() override;
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void EndBestEffortFence() override;
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void BeginFizzlingBlockShutdownTasks() override;
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void EndFizzlingBlockShutdownTasks() override;
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// PooledTaskRunnerDelegate:
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bool EnqueueJobTaskSource(scoped_refptr<JobTaskSource> task_source) override;
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void RemoveJobTaskSource(scoped_refptr<JobTaskSource> task_source) override;
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void UpdatePriority(scoped_refptr<TaskSource> task_source,
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TaskPriority priority) override;
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void UpdateJobPriority(scoped_refptr<TaskSource> task_source,
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TaskPriority priority) override;
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// Returns the TimeTicks of the next task scheduled on ThreadPool (Now() if
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// immediate, nullopt if none). This is thread-safe, i.e., it's safe if tasks
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// are being posted in parallel with this call but such a situation obviously
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// results in a race as to whether this call will see the new tasks in time.
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absl::optional<TimeTicks> NextScheduledRunTimeForTesting() const;
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// Forces ripe delayed tasks to be posted (e.g. when time is mocked and
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// advances faster than the real-time delay on ServiceThread).
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void ProcessRipeDelayedTasksForTesting();
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// Requests that all threads started by future ThreadPoolImpls in this process
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// have a synchronous start (if |enabled|; cancels this behavior otherwise).
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// Must be called while no ThreadPoolImpls are alive in this process. This is
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// exposed here on this internal API rather than as a ThreadPoolInstance
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// configuration param because only one internal test truly needs this.
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static void SetSynchronousThreadStartForTesting(bool enabled);
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// Posts |task| with a |delay| and specific |traits|. |delay| can be zero. For
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// one off tasks that don't require a TaskRunner. Returns false if the task
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// definitely won't run because of current shutdown state.
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bool PostDelayedTask(const Location& from_here,
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const TaskTraits& traits,
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OnceClosure task,
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TimeDelta delay);
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// Returns a TaskRunner whose PostTask invocations result in scheduling tasks
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// using |traits|. Tasks may run in any order and in parallel.
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scoped_refptr<TaskRunner> CreateTaskRunner(const TaskTraits& traits);
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// Returns a SequencedTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits|. Tasks run one at a time in posting order.
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scoped_refptr<SequencedTaskRunner> CreateSequencedTaskRunner(
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const TaskTraits& traits);
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// Returns a SingleThreadTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits|. Tasks run on a single thread in posting
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// order. If |traits| identifies an existing thread,
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// SingleThreadTaskRunnerThreadMode::SHARED must be used.
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scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunner(
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const TaskTraits& traits,
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SingleThreadTaskRunnerThreadMode thread_mode);
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#if BUILDFLAG(IS_WIN)
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// Returns a SingleThreadTaskRunner whose PostTask invocations result in
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// scheduling tasks using |traits| in a COM Single-Threaded Apartment. Tasks
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// run in the same Single-Threaded Apartment in posting order for the returned
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// SingleThreadTaskRunner. If |traits| identifies an existing thread,
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// SingleThreadTaskRunnerThreadMode::SHARED must be used.
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scoped_refptr<SingleThreadTaskRunner> CreateCOMSTATaskRunner(
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const TaskTraits& traits,
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SingleThreadTaskRunnerThreadMode thread_mode);
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#endif // BUILDFLAG(IS_WIN)
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// Returns a task runner whose PostTask invocations result in scheduling tasks
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// using |traits|. The priority in |traits| can be updated at any time via
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// UpdateableSequencedTaskRunner::UpdatePriority(). An update affects all
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// tasks posted to the task runner that aren't running yet. Tasks run one at a
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// time in posting order.
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//
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// |traits| requirements:
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// - base::ThreadPolicy must be specified if the priority of the task runner
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// will ever be increased from BEST_EFFORT.
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scoped_refptr<UpdateableSequencedTaskRunner>
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CreateUpdateableSequencedTaskRunner(const TaskTraits& traits);
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private:
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// Invoked after |num_fences_| or |num_best_effort_fences_| is updated. Sets
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// the CanRunPolicy in TaskTracker and wakes up workers as appropriate.
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void UpdateCanRunPolicy();
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const ThreadGroup* GetThreadGroupForTraits(const TaskTraits& traits) const;
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// ThreadGroup::Delegate:
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ThreadGroup* GetThreadGroupForTraits(const TaskTraits& traits) override;
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// Posts |task| to be executed by the appropriate thread group as part of
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// |sequence|. This must only be called after |task| has gone through
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// TaskTracker::WillPostTask() and after |task|'s delayed run time.
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bool PostTaskWithSequenceNow(Task task, scoped_refptr<Sequence> sequence);
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// PooledTaskRunnerDelegate:
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bool PostTaskWithSequence(Task task,
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scoped_refptr<Sequence> sequence) override;
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bool ShouldYield(const TaskSource* task_source) override;
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const std::string histogram_label_;
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const std::unique_ptr<TaskTrackerImpl> task_tracker_;
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ServiceThread service_thread_;
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DelayedTaskManager delayed_task_manager_;
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PooledSingleThreadTaskRunnerManager single_thread_task_runner_manager_;
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std::unique_ptr<ThreadGroup> foreground_thread_group_;
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std::unique_ptr<ThreadGroup> utility_thread_group_;
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std::unique_ptr<ThreadGroup> background_thread_group_;
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// Whether this TaskScheduler was started.
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bool started_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
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// Whether the --disable-best-effort-tasks switch is preventing execution of
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// BEST_EFFORT tasks until shutdown.
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const bool has_disable_best_effort_switch_;
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// Number of fences preventing execution of tasks of any/BEST_EFFORT priority.
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int num_fences_ GUARDED_BY_CONTEXT(sequence_checker_) = 0;
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int num_best_effort_fences_ GUARDED_BY_CONTEXT(sequence_checker_) = 0;
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#if DCHECK_IS_ON()
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// Set once JoinForTesting() has returned.
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AtomicFlag join_for_testing_returned_;
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#endif
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#if BUILDFLAG(IS_WIN) && defined(COM_INIT_CHECK_HOOK_ENABLED)
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// Provides COM initialization verification for supported builds.
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base::win::ComInitCheckHook com_init_check_hook_;
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#endif
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// Asserts that operations occur in sequence with Start().
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SEQUENCE_CHECKER(sequence_checker_);
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TrackedRefFactory<ThreadGroup::Delegate> tracked_ref_factory_;
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};
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} // namespace internal
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} // namespace base
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#endif // BASE_TASK_THREAD_POOL_THREAD_POOL_IMPL_H_
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