tor-browser

HRTFDatabaseLoader.h (5433B)

---

/*
* 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;
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*/

#ifndef HRTFDatabaseLoader_h
#define HRTFDatabaseLoader_h

#include "HRTFDatabase.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Mutex.h"
#include "nsHashKeys.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