Source/WebCore/platform/audio/HRTFDatabaseLoader.cpp

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
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 *     notice, this list of conditions and the following disclaimer in the
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "HRTFDatabaseLoader.h"

#include "HRTFDatabase.h"
#include <wtf/HashMap.h>
#include <wtf/MainThread.h>
#include <wtf/NeverDestroyed.h>

namespace WebCore {

// Keeps track of loaders on a per-sample-rate basis.
static HashMap<double, HRTFDatabaseLoader*>& loaderMap()
{
    static NeverDestroyed<HashMap<double, HRTFDatabaseLoader*>> loaderMap;
    return loaderMap;
}

Ref<HRTFDatabaseLoader> HRTFDatabaseLoader::createAndLoadAsynchronouslyIfNecessary(float sampleRate)
{
    ASSERT(isMainThread());

    if (RefPtr<HRTFDatabaseLoader> loader = loaderMap().get(sampleRate)) {
        ASSERT(sampleRate == loader->databaseSampleRate());
        return loader.releaseNonNull();
    }

    auto loader = adoptRef(*new HRTFDatabaseLoader(sampleRate));
    loaderMap().add(sampleRate, loader.ptr());

    loader->loadAsynchronously();

    return loader;
}

HRTFDatabaseLoader::HRTFDatabaseLoader(float sampleRate)
    : m_databaseSampleRate(sampleRate)
{
    ASSERT(isMainThread());
}

HRTFDatabaseLoader::~HRTFDatabaseLoader()
{
    ASSERT(isMainThread());

    waitForLoaderThreadCompletion();
    m_hrtfDatabase = nullptr;

    // Remove ourself from the map.
    loaderMap().remove(m_databaseSampleRate);
}

void HRTFDatabaseLoader::load()
{
    ASSERT(!isMainThread());
    if (!m_hrtfDatabase.get()) {
        // Load the default HRTF database.
        m_hrtfDatabase = makeUnique<HRTFDatabase>(m_databaseSampleRate);
    }
}

void HRTFDatabaseLoader::loadAsynchronously()
{
    ASSERT(isMainThread());

    Locker locker { m_threadLock };
    
    if (!m_hrtfDatabase.get() && !m_databaseLoaderThread) {
        // Start the asynchronous database loading process.
        m_databaseLoaderThread = Thread::create("HRTF database loader", [this] {
            load();
        });
    }
}

bool HRTFDatabaseLoader::isLoaded() const
{
    return m_hrtfDatabase.get();
}

void HRTFDatabaseLoader::waitForLoaderThreadCompletion()
{
    Locker locker { m_threadLock };
    
    // waitForThreadCompletion() should not be called twice for the same thread.
    if (m_databaseLoaderThread)
        m_databaseLoaderThread->waitForCompletion();
    m_databaseLoaderThread = nullptr;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)