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// Copyright 2019 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_SINGLE_THREAD_TASK_EXECUTOR_H_
#define BASE_TASK_SINGLE_THREAD_TASK_EXECUTOR_H_
#include <memory>
#include "base/base_export.h"
#include "base/memory/scoped_refptr.h"
#include "base/message_loop/message_pump_type.h"
#include "base/task/sequence_manager/task_queue.h"
#include "base/task/single_thread_task_runner.h"
namespace base {
class MessagePump;
namespace sequence_manager {
class SequenceManager;
} // namespace sequence_manager
// A simple single thread TaskExecutor intended for non-test usage. Tests should
// generally use TaskEnvironment or BrowserTaskEnvironment instead.
class BASE_EXPORT SingleThreadTaskExecutor {
public:
// For MessagePumpType::CUSTOM use the constructor that takes a pump.
explicit SingleThreadTaskExecutor(
MessagePumpType type = MessagePumpType::DEFAULT);
// Creates a SingleThreadTaskExecutor pumping from a custom |pump|.
// The above constructor using MessagePumpType is generally preferred.
explicit SingleThreadTaskExecutor(std::unique_ptr<MessagePump> pump);
SingleThreadTaskExecutor(const SingleThreadTaskExecutor&) = delete;
SingleThreadTaskExecutor& operator=(const SingleThreadTaskExecutor&) = delete;
// Shuts down the SingleThreadTaskExecutor, after this no tasks can be
// executed and the base::TaskExecutor APIs are non-functional but won't crash
// if called.
~SingleThreadTaskExecutor();
const scoped_refptr<SingleThreadTaskRunner>& task_runner() const;
MessagePumpType type() const { return type_; }
// Sets the number of application tasks executed every time the MessagePump
// asks its delegate to DoWork(). Defaults to 1. Can be increased in some
// scenarios where the native pump (i.e. not MessagePumpType::DEFAULT) has
// high overhead and yielding to native isn't critical.
void SetWorkBatchSize(int work_batch_size);
private:
explicit SingleThreadTaskExecutor(MessagePumpType type,
std::unique_ptr<MessagePump> pump);
std::unique_ptr<sequence_manager::SequenceManager> sequence_manager_;
sequence_manager::TaskQueue::Handle default_task_queue_;
MessagePumpType type_;
};
} // namespace base
#endif // BASE_TASK_SINGLE_THREAD_TASK_EXECUTOR_H_
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