Source/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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 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
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 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     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 "platform/WebThreadSupportingGC.h"
#include "platform/audio/HRTFDatabase.h"
#include "platform/heap/Handle.h"
#include "wtf/HashMap.h"
#include "wtf/ThreadingPrimitives.h"

namespace blink {

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

class PLATFORM_EXPORT HRTFDatabaseLoader final : public GarbageCollectedFinalized<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 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();

    // 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; }

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

    void trace(Visitor*) { }

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();

    // Holding a m_lock is required when accessing m_hrtfDatabase since we access it from multiple threads.
    Mutex m_lock;
    OwnPtr<HRTFDatabase> m_hrtfDatabase;

    OwnPtr<WebThreadSupportingGC> m_thread;

    float m_databaseSampleRate;
};

} // namespace blink

#endif // HRTFDatabaseLoader_h