/*
 * 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() {
    if (!m_databaseLoaded) {
      return nullptr;
    }
    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 MOZ_GUARDED_BY(m_threadLock);

  float m_databaseSampleRate;
  mozilla::Atomic<bool> m_databaseLoaded;
};

}  // namespace WebCore

#endif  // HRTFDatabaseLoader_h