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// 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 MEDIA_MIDI_MIDI_SERVICE_H_
#define MEDIA_MIDI_MIDI_SERVICE_H_
#include <stdint.h>
#include <memory>
#include <vector>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread.h"
#include "media/midi/midi_export.h"
#include "media/midi/midi_manager.h"
namespace midi {
// Manages MidiManager backends. This class expects to be constructed and
// destructed on the browser main thread, but methods can be called on both
// the main thread and the I/O thread.
class MIDI_EXPORT MidiService final {
public:
// Use the first constructor for production code.
MidiService();
// |MidiManager| can be explicitly specified in the constructor for testing.
explicit MidiService(std::unique_ptr<MidiManager> manager);
~MidiService();
// Called on the browser main thread to notify the I/O thread will stop and
// the instance will be destructed on the main thread soon.
void Shutdown();
// A client calls StartSession() to receive and send MIDI data.
void StartSession(MidiManagerClient* client);
// A client calls EndSession() to stop receiving MIDI data.
void EndSession(MidiManagerClient* client);
// A client calls DispatchSendMidiData() to send MIDI data.
void DispatchSendMidiData(MidiManagerClient* client,
uint32_t port_index,
const std::vector<uint8_t>& data,
double timestamp);
// Returns a SingleThreadTaskRunner reference to serve MidiManager. Each
// TaskRunner will be constructed on demand.
// MidiManager that supports the dynamic instantiation feature will use this
// method to post tasks that should not run on I/O. Since TaskRunners outlive
// MidiManager, each task should ensure that MidiManager that posted the task
// is still alive while accessing |this|. TaskRunners will be reused when
// another MidiManager is instantiated.
scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner(size_t runner_id);
private:
// Holds MidiManager instance. If the dynamic instantiation feature is
// enabled, the MidiManager would be constructed and destructed on the I/O
// thread, and all MidiManager methods would be called on the I/O thread.
std::unique_ptr<MidiManager> manager_;
// A flag to indicate if the dynamic instantiation feature is supported and
// actually enabled.
const bool is_dynamic_instantiation_enabled_;
// Counts active clients to manage dynamic MidiManager instantiation.
size_t active_clients_;
// Protects all members above.
base::Lock lock_;
// Threads to host SingleThreadTaskRunners.
std::vector<std::unique_ptr<base::Thread>> threads_;
// Protects |threads_|.
base::Lock threads_lock_;
DISALLOW_COPY_AND_ASSIGN(MidiService);
};
} // namespace midi
#endif // MEDIA_MIDI_MIDI_SERVICE_H_
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