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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QAUDIOSTATEMACHINE_P_H
#define QAUDIOSTATEMACHINE_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <QtMultimedia/qaudio.h>
#include <qmutex.h>
#include <qwaitcondition.h>
#include <qpointer.h>
#include <atomic>
#include <chrono>
QT_BEGIN_NAMESPACE
class QAudioStateChangeNotifier;
/* QAudioStateMachine provides an opportunity to
* toggle QAudio::State with QAudio::Error in
* a thread-safe manner.
* The toggling functions return a guard,
* which scope guaranties thread safety (if synchronization enabled)
* and notifies about the change via
* QAudioStateChangeNotifier::stateChanged and errorChanged.
*
* The state machine is supposed to be used mostly in
* QAudioSink and QAudioSource implementations.
*/
class Q_MULTIMEDIA_EXPORT QAudioStateMachine
{
public:
using RawState = int;
class StateChangeGuard
{
public:
void reset()
{
if (auto stateMachine = std::exchange(m_stateMachine, nullptr))
stateMachine->reset(m_state, m_prevState, m_error);
}
~StateChangeGuard() { reset(); }
StateChangeGuard(const StateChangeGuard &) = delete;
StateChangeGuard(StateChangeGuard &&other) noexcept
: m_stateMachine(std::exchange(other.m_stateMachine, nullptr)),
m_state(other.m_state),
m_prevState(other.m_prevState),
m_error(other.m_error)
{
}
operator bool() const { return m_stateMachine != nullptr; }
void setError(QAudio::Error error) { m_error = error; }
// Can be added make state changing more flexible
// but needs some investigation to ensure state change consistency
// The method is supposed to be used for sync read/write
// under "guard = updateActiveOrIdle(isActive)"
// void setState(QAudio::State state) { ... }
bool isStateChanged() const { return m_state != m_prevState; }
QAudio::State prevState() const { return QAudio::State(m_prevState); }
private:
StateChangeGuard(QAudioStateMachine *stateMachine = nullptr,
RawState state = QAudio::StoppedState,
RawState prevState = QAudio::StoppedState,
QAudio::Error error = QAudio::NoError)
: m_stateMachine(stateMachine), m_state(state), m_prevState(prevState), m_error(error)
{
}
private:
QAudioStateMachine *m_stateMachine;
RawState m_state;
const RawState m_prevState;
QAudio::Error m_error;
friend class QAudioStateMachine;
};
QAudioStateMachine(QAudioStateChangeNotifier ¬ifier, bool synchronize = true);
~QAudioStateMachine();
QAudio::State state() const;
QAudio::Error error() const;
bool isDraining() const;
bool isActiveOrIdle() const;
// atomicaly checks if the state is stopped and marked as drained
std::pair<bool, bool> getDrainedAndStopped() const;
// waits if the method stop(error, true) has bee called
void waitForDrained(std::chrono::milliseconds timeout);
// mark as drained and wake up the method waitForDrained
void onDrained();
// Active/Idle/Suspended -> Stopped
StateChangeGuard stop(QAudio::Error error = QAudio::NoError, bool shouldDrain = false,
bool forceUpdateError = false);
// Active/Idle/Suspended -> Stopped
StateChangeGuard stopOrUpdateError(QAudio::Error error = QAudio::NoError)
{
return stop(error, false, true);
}
// Stopped -> Active/Idle
StateChangeGuard start(bool isActive = true);
// Active/Idle -> Suspended + saves the exchanged state
StateChangeGuard suspend();
// Suspended -> saved state (Active/Idle)
StateChangeGuard resume();
// Idle -> Active
StateChangeGuard activateFromIdle();
// Active/Idle -> Active/Idle + updateError
StateChangeGuard updateActiveOrIdle(bool isActive, QAudio::Error error = QAudio::NoError);
// Any -> Any; better use more strict methods
StateChangeGuard forceSetState(QAudio::State state, QAudio::Error error = QAudio::NoError);
// force set the error
void setError(QAudio::Error error);
private:
StateChangeGuard changeState(std::pair<RawState, uint32_t> prevStatesSet, RawState state,
QAudio::Error error = QAudio::NoError, bool shouldDrain = false);
void reset(RawState state, RawState prevState, QAudio::Error error);
private:
QPointer<QAudioStateChangeNotifier> m_notifier;
std::atomic<RawState> m_state = QAudio::StoppedState;
std::atomic<QAudio::Error> m_error = QAudio::NoError;
RawState m_suspendedInState = QAudio::SuspendedState;
struct Synchronizer;
std::unique_ptr<Synchronizer> m_sychronizer;
};
QT_END_NAMESPACE
#endif // QAUDIOSTATEMACHINE_P_H
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