/*

 * Copyright (C) 2010 Google Inc. All rights reserved.

 *

 * 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

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#ifndef HRTFDatabaseLoader_h

#define HRTFDatabaseLoader_h

#include "nsHashKeys.h"

#include "mozilla/RefPtr.h"

#include "mozilla/MemoryReporting.h"

#include "mozilla/Mutex.h"

#include "HRTFDatabase.h"

template <class EntryType> class nsTHashtable;

template <class T> class nsAutoRef;

namespace WebCore {

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

class 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 already_AddRefed<HRTFDatabaseLoader> createAndLoadAsynchronouslyIfNecessary(float sampleRate);

    // AddRef and Release may be called from any thread.

    void AddRef()

    {

#if defined(DEBUG) || defined(NS_BUILD_REFCNT_LOGGING)

        int count =

#endif

          ++m_refCnt;

        MOZ_ASSERT(count > 0, "invalid ref count");

        NS_LOG_ADDREF(this, count, "HRTFDatabaseLoader", sizeof(*this));

    }

    void Release()

    {

        // The last reference can't be removed on a non-main thread because

        // the object can be accessed on the main thread from the hash

        // table via createAndLoadAsynchronouslyIfNecessary().

        int count = m_refCnt;

        MOZ_ASSERT(count > 0, "extra release");

        // Optimization attempt to possibly skip proxying the release to the

        // main thread.

        if (count != 1 && m_refCnt.compareExchange(count, count - 1)) {

            NS_LOG_RELEASE(this, count - 1, "HRTFDatabaseLoader");

            return;

        }

        ProxyRelease();

    }

    // Returns true once the default database has been completely loaded.

    bool isLoaded() const;

    // waitForLoaderThreadCompletion() may be called more than once,

    // on any thread except m_databaseLoaderThread.

    void waitForLoaderThreadCompletion();

    HRTFDatabase* database() { return m_hrtfDatabase.get(); }

    float databaseSampleRate() const { return m_databaseSampleRate; }

    static void shutdown();

    // Called in asynchronous loading thread.

    void load();

    // Sums the size of all cached database loaders.

    static size_t sizeOfLoaders(mozilla::MallocSizeOf aMallocSizeOf);

private:

    // Both constructor and destructor must be called from the main thread.

    explicit HRTFDatabaseLoader(float sampleRate);

    ~HRTFDatabaseLoader();

    size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

    void ProxyRelease(); // any thread

    void MainThreadRelease(); // main thread only

    class ProxyReleaseEvent;

    // 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.

    class LoaderByRateEntry : public nsFloatHashKey {

    public:

        explicit LoaderByRateEntry(KeyTypePointer aKey)

            : nsFloatHashKey(aKey)

            , mLoader() // so PutEntry() will zero-initialize

        {

        }

        size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const

        {

            return mLoader ? mLoader->sizeOfIncludingThis(aMallocSizeOf) : 0;

        }

        // The HRTFDatabaseLoader removes itself from s_loaderMap on destruction.

        HRTFDatabaseLoader* MOZ_NON_OWNING_REF mLoader;

    };

    // Keeps track of loaders on a per-sample-rate basis.

    static nsTHashtable<LoaderByRateEntry> *s_loaderMap; // singleton

    mozilla::Atomic<int> m_refCnt;

    nsAutoRef<HRTFDatabase> m_hrtfDatabase;

    // Holding a m_threadLock is required when accessing m_databaseLoaderThread.

    mozilla::Mutex m_threadLock;

    PRThread* m_databaseLoaderThread;

    float m_databaseSampleRate;

};

} // namespace WebCore

#endif // HRTFDatabaseLoader_h