HRTFDatabaseLoader.h   [plain text]

/*
 * 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
 * are met:
 *
 * 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
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 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
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#ifndef HRTFDatabaseLoader_h
#define HRTFDatabaseLoader_h

#include "HRTFDatabase.h"
#include <wtf/PassRefPtr.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 the singleton HRTFDatabaseLoader (if not already created) and starts loading asynchronously (when created the first time).
    // Returns the singleton HRTFDatabaseLoader.
    // Must be called from the main thread.
    static PassRefPtr<HRTFDatabaseLoader> createAndLoadAsynchronouslyIfNecessary(float sampleRate);

    // Returns the singleton HRTFDatabaseLoader.
    static HRTFDatabaseLoader* loader() { return s_loader; }
    
    // 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; }
    
    // Called in asynchronous loading thread.
    void load();

    // defaultHRTFDatabase() gives access to the loaded database.
    // This can be called from any thread, but it is the callers responsibilty to call this while the context (and thus HRTFDatabaseLoader)
    // is still alive.  Otherwise this will return 0.
    static HRTFDatabase* defaultHRTFDatabase();

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();

    static HRTFDatabaseLoader* s_loader; // singleton
    OwnPtr<HRTFDatabase> m_hrtfDatabase;

    // Holding a m_threadLock is required when accessing m_databaseLoaderThread.
    Mutex m_threadLock;
    ThreadIdentifier m_databaseLoaderThread;

    float m_databaseSampleRate;
};

} // namespace WebCore

#endif // HRTFDatabaseLoader_h