author Chris Peterson <>
Fri, 18 Dec 2015 00:51:16 -0800
changeset 277033 f19858fd5e8f0af2a1e4d21eb1521c12615b9172
parent 268184 e8c7dfe727cd970e2c3294934e2927b14143c205
child 295627 3d3cc3ecdca6c6de7b69c34a551bd8f61b903a97
permissions -rw-r--r--
Bug 1232223 - Part 3: Remove MOZ_WAVE #ifdefs because Wave is always supported. r=jya

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at */

 * DecodePool manages the threads used for decoding raster images.

#ifndef mozilla_image_DecodePool_h
#define mozilla_image_DecodePool_h

#include "mozilla/Mutex.h"
#include "mozilla/StaticPtr.h"
#include "nsCOMArray.h"
#include "nsCOMPtr.h"
#include "nsIEventTarget.h"
#include "nsIObserver.h"
#include "mozilla/RefPtr.h"

class nsIThread;
class nsIThreadPool;

namespace mozilla {
namespace image {

class Decoder;
class DecodePoolImpl;

 * DecodePool is a singleton class that manages decoding of raster images. It
 * owns a pool of image decoding threads that are used for asynchronous
 * decoding.
 * DecodePool allows callers to run a decoder, handling management of the
 * decoder's lifecycle and whether it executes on the main thread,
 * off-main-thread in the image decoding thread pool, or on some combination of
 * the two.
class DecodePool : public nsIObserver

  /// Initializes the singleton instance. Should be called from the main thread.
  static void Initialize();

  /// Returns the singleton instance.
  static DecodePool* Singleton();

  /// @return the number of processor cores we have available. This is not the
  /// same as the number of decoding threads we're actually using.
  static uint32_t NumberOfCores();

  /// Ask the DecodePool to run @aDecoder asynchronously and return immediately.
  void AsyncDecode(Decoder* aDecoder);

   * Run @aDecoder synchronously if the image it's decoding is small. If the
   * image is too large, or if the source data isn't complete yet, run @aDecoder
   * asynchronously instead.
  void SyncDecodeIfSmall(Decoder* aDecoder);

   * Run aDecoder synchronously if at all possible. If it can't complete
   * synchronously because the source data isn't complete, asynchronously decode
   * the rest.
  void SyncDecodeIfPossible(Decoder* aDecoder);

   * Returns an event target interface to the DecodePool's I/O thread. Callers
   * who want to deliver data to workers on the DecodePool can use this event
   * target.
   * @return An nsIEventTarget interface to the thread pool's I/O thread.
  already_AddRefed<nsIEventTarget> GetIOEventTarget();

  friend class DecodePoolWorker;

  virtual ~DecodePool();

  void Decode(Decoder* aDecoder);
  void NotifyDecodeComplete(Decoder* aDecoder);
  void NotifyProgress(Decoder* aDecoder);

  static StaticRefPtr<DecodePool> sSingleton;
  static uint32_t sNumCores;

  RefPtr<DecodePoolImpl>    mImpl;

  // mMutex protects mThreads and mIOThread.
  Mutex                     mMutex;
  nsCOMArray<nsIThread>     mThreads;
  nsCOMPtr<nsIThread>       mIOThread;

} // namespace image
} // namespace mozilla

#endif // mozilla_image_DecodePool_h