Source/WebCore/Modules/webaudio/OfflineAudioContext.cpp

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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "OfflineAudioContext.h"

#include "AudioBuffer.h"
#include "AudioUtilities.h"
#include "Document.h"
#include "JSAudioBuffer.h"
#include "OfflineAudioCompletionEvent.h"
#include "OfflineAudioContextOptions.h"
#include <wtf/IsoMallocInlines.h>
#include <wtf/Scope.h>

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(OfflineAudioContext);

OfflineAudioContext::OfflineAudioContext(Document& document, const OfflineAudioContextOptions& options)
    : BaseAudioContext(document)
    , m_destinationNode(makeUniqueRef<OfflineAudioDestinationNode>(*this, options.numberOfChannels, options.sampleRate, AudioBuffer::create(options.numberOfChannels, options.length, options.sampleRate)))
    , m_length(options.length)
{
    if (!renderTarget())
        document.addConsoleMessage(MessageSource::JS, MessageLevel::Warning, makeString("Failed to construct internal AudioBuffer with ", options.numberOfChannels, " channel(s), a sample rate of ", options.sampleRate, " and a length of ", options.length, "."));
}

ExceptionOr<Ref<OfflineAudioContext>> OfflineAudioContext::create(ScriptExecutionContext& context, const OfflineAudioContextOptions& options)
{
    if (!is<Document>(context))
        return Exception { NotSupportedError, "OfflineAudioContext is only supported in Document contexts"_s };
    if (!options.numberOfChannels || options.numberOfChannels > maxNumberOfChannels)
        return Exception { NotSupportedError, "Number of channels is not in range"_s };
    if (!options.length)
        return Exception { NotSupportedError, "length cannot be 0"_s };
    if (!isSupportedSampleRate(options.sampleRate))
        return Exception { NotSupportedError, "sampleRate is not in range"_s };

    auto audioContext = adoptRef(*new OfflineAudioContext(downcast<Document>(context), options));
    audioContext->suspendIfNeeded();
    return audioContext;
}

ExceptionOr<Ref<OfflineAudioContext>> OfflineAudioContext::create(ScriptExecutionContext& context, unsigned numberOfChannels, unsigned length, float sampleRate)
{
    return create(context, { numberOfChannels, length, sampleRate });
}

void OfflineAudioContext::uninitialize()
{
    if (!isInitialized())
        return;

    BaseAudioContext::uninitialize();

    if (auto promise = std::exchange(m_pendingRenderingPromise, nullptr))
        promise->reject(Exception { InvalidStateError, "Context is going away"_s });
}

const char* OfflineAudioContext::activeDOMObjectName() const
{
    return "OfflineAudioContext";
}

void OfflineAudioContext::startRendering(Ref<DeferredPromise>&& promise)
{
    if (isStopped()) {
        promise->reject(Exception { InvalidStateError, "Context is stopped"_s });
        return;
    }

    if (m_didStartRendering) {
        promise->reject(Exception { InvalidStateError, "Rendering was already started"_s });
        return;
    }

    if (!renderTarget()) {
        promise->reject(Exception { NotSupportedError, "Failed to create audio buffer"_s });
        return;
    }

    lazyInitialize();

    destination().startRendering([this, promise = WTFMove(promise), pendingActivity = makePendingActivity(*this)](std::optional<Exception>&& exception) mutable {
        if (exception) {
            promise->reject(WTFMove(*exception));
            return;
        }

        m_pendingRenderingPromise = WTFMove(promise);
        m_didStartRendering = true;
        setState(State::Running);
    });
}

void OfflineAudioContext::suspendRendering(double suspendTime, Ref<DeferredPromise>&& promise)
{
    if (isStopped()) {
        promise->reject(Exception { InvalidStateError, "Context is stopped"_s });
        return;
    }

    if (suspendTime < 0) {
        promise->reject(Exception { InvalidStateError, "suspendTime cannot be negative"_s });
        return;
    }

    double totalRenderDuration = length() / sampleRate();
    if (totalRenderDuration <= suspendTime) {
        promise->reject(Exception { InvalidStateError, "suspendTime cannot be greater than total rendering duration"_s });
        return;
    }

    size_t frame = AudioUtilities::timeToSampleFrame(suspendTime, sampleRate());
    frame = AudioUtilities::renderQuantumSize * ((frame + AudioUtilities::renderQuantumSize - 1) / AudioUtilities::renderQuantumSize);
    if (frame < currentSampleFrame()) {
        promise->reject(Exception { InvalidStateError, "Suspension frame is earlier than current frame"_s });
        return;
    }

    Locker locker { graphLock() };
    auto addResult = m_suspendRequests.add(frame, promise.ptr());
    if (!addResult.isNewEntry) {
        promise->reject(Exception { InvalidStateError, "There is already a pending suspend request at this frame"_s });
        return;
    }
}

void OfflineAudioContext::resumeRendering(Ref<DeferredPromise>&& promise)
{
    if (!m_didStartRendering) {
        promise->reject(Exception { InvalidStateError, "Cannot resume an offline audio context that has not started"_s });
        return;
    }
    if (isClosed()) {
        promise->reject(Exception { InvalidStateError, "Cannot resume an offline audio context that is closed"_s });
        return;
    }
    if (state() == AudioContextState::Running) {
        promise->resolve();
        return;
    }
    ASSERT(state() == AudioContextState::Suspended);

    destination().startRendering([this, promise = WTFMove(promise), pendingActivity = makePendingActivity(*this)](std::optional<Exception>&& exception) mutable {
        if (exception) {
            promise->reject(WTFMove(*exception));
            return;
        }

        setState(State::Running);
        promise->resolve();
    });
}

bool OfflineAudioContext::shouldSuspend()
{
    ASSERT(!isMainThread());
    // Note that we are not using a tryLock() here. We usually avoid blocking the AudioThread
    // on lock() but we don't have a choice here since the suspension need to be exact.
    // Also, this not a real-time AudioContext so blocking the AudioThread is not as harmful.
    Locker locker { graphLock() };
    return m_suspendRequests.contains(currentSampleFrame());
}

void OfflineAudioContext::didSuspendRendering(size_t frame)
{
    setState(State::Suspended);

    RefPtr<DeferredPromise> promise;
    {
        Locker locker { graphLock() };
        promise = m_suspendRequests.take(frame);
    }
    ASSERT(promise);
    if (promise)
        promise->resolve();
}

void OfflineAudioContext::finishedRendering(bool didRendering)
{
    ASSERT(isMainThread());
    ALWAYS_LOG(LOGIDENTIFIER);

    auto uninitializeOnExit = makeScopeExit([this] {
        uninitialize();
        clear();
    });

    // Make sure our JSwrapper stays alive long enough to resolve the promise and queue the completion event.
    // Otherwise, setting the state to Closed may cause our JS wrapper to get collected early.
    auto protectedJSWrapper = makePendingActivity(*this);
    setState(State::Closed);

    // Avoid firing the event if the document has already gone away.
    if (isStopped())
        return;

    RefPtr<AudioBuffer> renderedBuffer = renderTarget();
    ASSERT(renderedBuffer);

    if (didRendering) {
        queueTaskToDispatchEvent(*this, TaskSource::MediaElement, OfflineAudioCompletionEvent::create(*renderedBuffer));
        settleRenderingPromise(renderedBuffer.releaseNonNull());
    } else
        settleRenderingPromise(Exception { InvalidStateError, "Offline rendering failed"_s });
}

void OfflineAudioContext::settleRenderingPromise(ExceptionOr<Ref<AudioBuffer>>&& result)
{
    auto promise = std::exchange(m_pendingRenderingPromise, nullptr);
    if (!promise)
        return;

    if (result.hasException()) {
        promise->reject(result.releaseException());
        return;
    }
    promise->resolve<IDLInterface<AudioBuffer>>(result.releaseReturnValue());
}

bool OfflineAudioContext::virtualHasPendingActivity() const
{
    return state() == State::Running;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)