Source/core/platform/audio/HRTFDatabaseLoader.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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#ifndef HRTFDatabaseLoader_h
#define HRTFDatabaseLoader_h

#include "core/platform/audio/HRTFDatabase.h"
#include "wtf/HashMap.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/RefPtr.h"
#include "wtf/Threading.h"
#include "wtf/ThreadingPrimitives.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 PassRefPtr<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; }

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

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();

    // Map from sample-rate to loader.
    typedef HashMap<double, HRTFDatabaseLoader*> LoaderMap;

    // Keeps track of loaders on a per-sample-rate basis.
    static LoaderMap* s_loaderMap; // 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