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109 lines
3.4 KiB
C++
109 lines
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* DecodePool manages the threads used for decoding raster images.
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*/
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#ifndef mozilla_image_DecodePool_h
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#define mozilla_image_DecodePool_h
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#include "mozilla/Mutex.h"
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#include "mozilla/StaticPtr.h"
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#include "nsCOMArray.h"
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#include "nsCOMPtr.h"
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#include "nsIEventTarget.h"
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#include "nsIObserver.h"
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#include "mozilla/RefPtr.h"
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#include "nsStringFwd.h"
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class nsIThread;
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class nsIThreadPool;
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namespace mozilla {
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namespace image {
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class Decoder;
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class DecodePoolImpl;
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class IDecodingTask;
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/**
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* DecodePool is a singleton class that manages decoding of raster images. It
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* owns a pool of image decoding threads that are used for asynchronous
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* decoding.
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*
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* DecodePool allows callers to run a decoder, handling management of the
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* decoder's lifecycle and whether it executes on the main thread,
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* off-main-thread in the image decoding thread pool, or on some combination of
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* the two.
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*/
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class DecodePool final : public nsIObserver {
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public:
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIOBSERVER
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/// Initializes the singleton instance. Should be called from the main thread.
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static void Initialize();
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/// Returns the singleton instance.
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static DecodePool* Singleton();
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/// @return the number of processor cores we have available. This is not the
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/// same as the number of decoding threads we're actually using.
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static uint32_t NumberOfCores();
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/// True if the DecodePool is being shutdown. This may only be called by
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/// threads from the pool to check if they should keep working or not.
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bool IsShuttingDown() const;
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/// Ask the DecodePool to run @aTask asynchronously and return immediately.
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void AsyncRun(IDecodingTask* aTask);
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/**
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* Run @aTask synchronously if the task would prefer it. It's up to the task
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* itself to make this decision; @see IDecodingTask::ShouldPreferSyncRun(). If
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* @aTask doesn't prefer it, just run @aTask asynchronously and return
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* immediately.
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* @return true if the task was run sync, false otherwise.
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*/
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bool SyncRunIfPreferred(IDecodingTask* aTask, const nsCString& aURI);
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/**
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* Run @aTask synchronously. This does not guarantee that @aTask will complete
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* synchronously. If, for example, @aTask doesn't yet have the data it needs
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* to run synchronously, it may recover by scheduling an async task to finish
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* up the work when the remaining data is available.
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*/
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void SyncRunIfPossible(IDecodingTask* aTask, const nsCString& aURI);
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/**
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* Returns an event target interface to the DecodePool's I/O thread. Callers
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* who want to deliver data to workers on the DecodePool can use this event
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* target.
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*
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* @return An nsIEventTarget interface to the thread pool's I/O thread.
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*/
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already_AddRefed<nsIEventTarget> GetIOEventTarget();
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private:
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friend class DecodePoolWorker;
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DecodePool();
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virtual ~DecodePool();
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static StaticRefPtr<DecodePool> sSingleton;
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static uint32_t sNumCores;
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bool mShuttingDown = false;
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// mMutex protects mIOThread.
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Mutex mMutex;
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nsCOMPtr<nsIThread> mIOThread MOZ_GUARDED_BY(mMutex);
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};
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} // namespace image
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} // namespace mozilla
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#endif // mozilla_image_DecodePool_h
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