// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_TASK_THREAD_POOL_POOLED_SEQUENCED_TASK_RUNNER_H_
#define BASE_TASK_THREAD_POOL_POOLED_SEQUENCED_TASK_RUNNER_H_

#include "base/base_export.h"
#include "base/functional/callback_forward.h"
#include "base/location.h"
#include "base/memory/raw_ptr.h"
#include "base/task/task_traits.h"
#include "base/task/thread_pool/pooled_task_runner_delegate.h"
#include "base/task/thread_pool/sequence.h"
#include "base/task/updateable_sequenced_task_runner.h"
#include "base/time/time.h"

namespace base {
namespace internal {

// A task runner that runs tasks in sequence.
class BASE_EXPORT PooledSequencedTaskRunner
    : public UpdateableSequencedTaskRunner {
 public:
  // Constructs a PooledSequencedTaskRunner which can be used to post tasks.
  PooledSequencedTaskRunner(
      const TaskTraits& traits,
      PooledTaskRunnerDelegate* pooled_task_runner_delegate);
  PooledSequencedTaskRunner(const PooledSequencedTaskRunner&) = delete;
  PooledSequencedTaskRunner& operator=(const PooledSequencedTaskRunner&) =
      delete;

  scoped_refptr<Sequence> sequence() { return sequence_; }

  // UpdateableSequencedTaskRunner:
  bool PostDelayedTask(const Location& from_here,
                       OnceClosure closure,
                       TimeDelta delay) override;

  bool PostDelayedTaskAt(subtle::PostDelayedTaskPassKey,
                         const Location& from_here,
                         OnceClosure closure,
                         TimeTicks delayed_run_time,
                         subtle::DelayPolicy delay_policy) override;

  bool PostNonNestableDelayedTask(const Location& from_here,
                                  OnceClosure closure,
                                  TimeDelta delay) override;

  bool RunsTasksInCurrentSequence() const override;

  void UpdatePriority(TaskPriority priority) override;

 private:
  ~PooledSequencedTaskRunner() override;

  // Dangling usage guarded by MatchesCurrentDelegate() checks.
  const raw_ptr<PooledTaskRunnerDelegate, DisableDanglingPtrDetection>
      pooled_task_runner_delegate_;

  // Sequence for all Tasks posted through this TaskRunner.
  const scoped_refptr<Sequence> sequence_;
};

}  // namespace internal
}  // namespace base

#endif  // BASE_TASK_THREAD_POOL_POOLED_SEQUENCED_TASK_RUNNER_H_