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Diffstat (limited to 'src/multimedia/audio/qaudiostatemachine.cpp')
-rw-r--r-- | src/multimedia/audio/qaudiostatemachine.cpp | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/src/multimedia/audio/qaudiostatemachine.cpp b/src/multimedia/audio/qaudiostatemachine.cpp new file mode 100644 index 000000000..4073abd48 --- /dev/null +++ b/src/multimedia/audio/qaudiostatemachine.cpp @@ -0,0 +1,264 @@ +// 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 + +#include "qaudiostatemachine_p.h" +#include "qaudiosystem_p.h" +#include <qpointer.h> +#include <qdebug.h> + +QT_BEGIN_NAMESPACE + +using Guard = QAudioStateMachine::StateChangeGuard; +using RawState = QAudioStateMachine::RawState; + +namespace { +constexpr RawState DrainingFlag = 1 << 16; +constexpr RawState InProgressFlag = 1 << 17; +constexpr RawState WaitingFlags = DrainingFlag | InProgressFlag; + +const auto IgnoreError = static_cast<QAudio::Error>(-1); + +inline bool isWaitingState(RawState state) +{ + return (state & WaitingFlags) != 0; +} + +inline bool isDrainingState(RawState state) +{ + return (state & DrainingFlag) != 0; +} + +inline RawState fromWaitingState(RawState state) +{ + return state & ~WaitingFlags; +} + +inline QAudio::State toAudioState(RawState state) +{ + return QAudio::State(fromWaitingState(state)); +} + +template<typename... States> +constexpr std::pair<RawState, uint32_t> makeStatesSet(QAudio::State first, States... others) +{ + return { first, ((1 << first) | ... | (1 << others)) }; +} + +// ensures compareExchange (testAndSet) operation with opportunity +// to check several states, can be considered as atomic +template<typename T, typename Predicate> +bool multipleCompareExchange(std::atomic<T> &target, T &prevValue, T newValue, Predicate predicate) +{ + Q_ASSERT(predicate(prevValue)); + do { + if (target.compare_exchange_strong(prevValue, newValue)) + return true; + } while (predicate(prevValue)); + + return false; +} + +} // namespace + +struct QAudioStateMachine::Synchronizer { + QMutex m_mutex; + QWaitCondition m_condition; + + template <typename Changer> + void changeState(Changer&& changer) { + { + QMutexLocker locker(&m_mutex); + changer(); + } + + m_condition.notify_all(); + } + + void waitForOperationFinished(std::atomic<RawState>& state) + { + QMutexLocker locker(&m_mutex); + while (isWaitingState(state)) + m_condition.wait(&m_mutex); + } + + void waitForDrained(std::atomic<RawState>& state, std::chrono::milliseconds timeout) { + QMutexLocker locker(&m_mutex); + if (isDrainingState(state)) + m_condition.wait(&m_mutex, timeout.count()); + } +}; + +QAudioStateMachine::QAudioStateMachine(QAudioStateChangeNotifier ¬ifier, bool synchronize) : + m_notifier(¬ifier), + m_sychronizer(synchronize ? std::make_unique<Synchronizer>() : nullptr) +{ +} + +QAudioStateMachine::~QAudioStateMachine() = default; + +QAudio::State QAudioStateMachine::state() const +{ + return toAudioState(m_state); +} + +QAudio::Error QAudioStateMachine::error() const +{ + return m_error; +} + +Guard QAudioStateMachine::changeState(std::pair<RawState, uint32_t> prevStatesSet, + RawState newState, QAudio::Error error, bool shouldDrain) +{ + auto checkState = [flags = prevStatesSet.second](RawState state) { + return (flags >> state) & 1; + }; + + if (!m_sychronizer) { + RawState prevState = prevStatesSet.first; + const auto exchanged = multipleCompareExchange( + m_state, prevState, newState, checkState); + + if (Q_LIKELY(exchanged)) + return { this, newState, prevState, error }; + + return {}; + } + + while (true) { + RawState prevState = prevStatesSet.first; + + const auto newWaitingState = newState | (shouldDrain ? WaitingFlags : InProgressFlag); + + const auto exchanged = multipleCompareExchange( + m_state, prevState, newWaitingState, [checkState](RawState state) { + return !isWaitingState(state) && checkState(state); + }); + + if (Q_LIKELY(exchanged)) + return { this, newState, prevState, error }; + + if (!isWaitingState(prevState)) + return {}; + + if (!checkState(fromWaitingState(prevState))) + return {}; + + m_sychronizer->waitForOperationFinished(m_state); + } +} + +Guard QAudioStateMachine::stop(QAudio::Error error, bool shouldDrain, bool forceUpdateError) +{ + auto result = changeState( + makeStatesSet(QAudio::ActiveState, QAudio::IdleState, QAudio::SuspendedState), + QAudio::StoppedState, error, shouldDrain); + + if (!result && forceUpdateError) + setError(error); + + return result; +} + +Guard QAudioStateMachine::start(bool active) +{ + return changeState(makeStatesSet(QAudio::StoppedState), + active ? QAudio::ActiveState : QAudio::IdleState); +} + +void QAudioStateMachine::waitForDrained(std::chrono::milliseconds timeout) +{ + if (m_sychronizer) + m_sychronizer->waitForDrained(m_state, timeout); +} + +void QAudioStateMachine::onDrained() +{ + if (m_sychronizer) + m_sychronizer->changeState([this]() { m_state &= ~DrainingFlag; }); +} + +bool QAudioStateMachine::isDraining() const +{ + return isDrainingState(m_state); +} + +bool QAudioStateMachine::isActiveOrIdle() const { + const auto state = this->state(); + return state == QAudio::ActiveState || state == QAudio::IdleState; +} + +std::pair<bool, bool> QAudioStateMachine::getDrainedAndStopped() const +{ + const RawState state = m_state; + return { !isDrainingState(state), toAudioState(state) == QAudio::StoppedState }; +} + +Guard QAudioStateMachine::suspend() +{ + // Due to the current documentation, we set QAudio::NoError. + // TBD: leave the previous error should be more reasonable (IgnoreError) + const auto error = QAudio::NoError; + auto result = changeState(makeStatesSet(QAudio::ActiveState, QAudio::IdleState), + QAudio::SuspendedState, error); + + if (result) + m_suspendedInState = result.prevState(); + + return result; +} + +Guard QAudioStateMachine::resume() +{ + // Due to the current documentation, we set QAudio::NoError. + // TBD: leave the previous error should be more reasonable (IgnoreError) + const auto error = QAudio::NoError; + return changeState(makeStatesSet(QAudio::SuspendedState), m_suspendedInState, error); +} + +Guard QAudioStateMachine::activateFromIdle() +{ + return changeState(makeStatesSet(QAudio::IdleState), QAudio::ActiveState); +} + +Guard QAudioStateMachine::updateActiveOrIdle(bool isActive, QAudio::Error error) +{ + const auto state = isActive ? QAudio::ActiveState : QAudio::IdleState; + return changeState(makeStatesSet(QAudio::ActiveState, QAudio::IdleState), state, error); +} + +void QAudioStateMachine::setError(QAudio::Error error) +{ + if (m_error.exchange(error) != error && m_notifier) + emit m_notifier->errorChanged(error); +} + +Guard QAudioStateMachine::forceSetState(QAudio::State state, QAudio::Error error) +{ + return changeState(makeStatesSet(QAudio::ActiveState, QAudio::IdleState, QAudio::SuspendedState, + QAudio::StoppedState), + state, error); +} + +void QAudioStateMachine::reset(RawState state, RawState prevState, QAudio::Error error) +{ + Q_ASSERT(!isWaitingState(state)); + + if (!m_sychronizer && m_state != state) + return; + + const auto isErrorChanged = error != IgnoreError && m_error.exchange(error) != error; + + if (m_sychronizer) + m_sychronizer->changeState([&](){ m_state = state; }); + + auto notifier = m_notifier; + + if (prevState != state && notifier) + emit notifier->stateChanged(toAudioState(state)); + + // check the notifier in case the object was deleted in + if (isErrorChanged && notifier) + emit notifier->errorChanged(error); +} + +QT_END_NAMESPACE |