Source/WebCore/platform/audio/HRTFDatabaseLoader.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * 2.  Redistributions in binary form must reproduce the above copyright
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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
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#ifndef HRTFDatabaseLoader_h
#define HRTFDatabaseLoader_h

#include "HRTFDatabase.h"
#include <memory>
#include <wtf/Lock.h>
#include <wtf/RefCounted.h>
#include <wtf/RefPtr.h>
#include <wtf/Threading.h>

namespace WebCore {

// HRTFDatabaseLoader will asynchronously load the default HRTFDatabase in a new thread.

class HRTFDatabaseLoader : public RefCounted<HRTFDatabaseLoader> {
public:
    // Lazily creates a HRTFDatabaseLoader (if not already created) for the given sample-rate
    // and starts loading asynchronously (when created the first time).
    // Returns the HRTFDatabaseLoader.
    // Must be called from the main thread.
    static Ref<HRTFDatabaseLoader> createAndLoadAsynchronouslyIfNecessary(float sampleRate);

    // Both constructor and destructor must be called from the main thread.
    ~HRTFDatabaseLoader();
    
    // Returns true once the default database has been completely loaded.
    bool isLoaded() const;

    // waitForLoaderThreadCompletion() may be called more than once and is thread-safe.
    void waitForLoaderThreadCompletion();
    
    HRTFDatabase* database() { return m_hrtfDatabase.get(); }

    float databaseSampleRate() const { return m_databaseSampleRate; }
    
private:
    // Both constructor and destructor must be called from the main thread.
    explicit HRTFDatabaseLoader(float sampleRate);
    
    // If it hasn't already been loaded, creates a new thread and initiates asynchronous loading of the default database.
    // This must be called from the main thread.
    void loadAsynchronously();

    // Called in asynchronous loading thread.
    void load();

    std::unique_ptr<HRTFDatabase> m_hrtfDatabase;

    // Holding a m_threadLock is required when accessing m_databaseLoaderThread.
    Lock m_threadLock;
    RefPtr<Thread> m_databaseLoaderThread WTF_GUARDED_BY_LOCK(m_threadLock);

    float m_databaseSampleRate;
};

} // namespace WebCore

#endif // HRTFDatabaseLoader_h