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90 lines
3.2 KiB
C++
90 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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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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#ifndef SharedThreadPool_h_
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#define SharedThreadPool_h_
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#include <queue>
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#include "mozilla/RefPtr.h"
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#include "nsThreadUtils.h"
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#include "nsIThreadPool.h"
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#include "nsISupports.h"
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#include "nsISupportsImpl.h"
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#include "nsCOMPtr.h"
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namespace mozilla {
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// Wrapper that makes an nsIThreadPool a singleton, and provides a
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// consistent threadsafe interface to get instances. Callers simply get a
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// SharedThreadPool by the name of its nsIThreadPool. All get requests of
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// the same name get the same SharedThreadPool. Users must store a reference
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// to the pool, and when the last reference to a SharedThreadPool is dropped
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// the pool is shutdown and deleted. Users aren't required to manually
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// shutdown the pool, and can release references on any thread. On Windows
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// all threads in the pool have MSCOM initialized with COINIT_MULTITHREADED.
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class SharedThreadPool : public nsIThreadPool
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{
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public:
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// Gets (possibly creating) the shared thread pool singleton instance with
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// thread pool named aName.
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// *Must* be called on the main thread.
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static TemporaryRef<SharedThreadPool> Get(const nsCString& aName,
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uint32_t aThreadLimit = 4);
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// Spins the event loop until all thread pools are shutdown.
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// *Must* be called on the main thread.
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static void SpinUntilShutdown();
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// We implement custom threadsafe AddRef/Release pair, that destroys the
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// the shared pool singleton when the refcount drops to 0. The addref/release
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// are implemented using locking, so it's not recommended that you use them
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// in a tight loop.
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NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr);
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NS_IMETHOD_(nsrefcnt) AddRef(void);
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NS_IMETHOD_(nsrefcnt) Release(void);
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// Forward behaviour to wrapped thread pool implementation.
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NS_FORWARD_SAFE_NSITHREADPOOL(mPool);
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NS_FORWARD_SAFE_NSIEVENTTARGET(GetEventTarget());
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nsIEventTarget* GetEventTarget() {
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return mEventTarget;
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}
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private:
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// Creates necessary statics.
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// Main thread only.
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static void EnsureInitialized();
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// Creates a singleton SharedThreadPool wrapper around aPool.
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// aName is the name of the aPool, and is used to lookup the
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// SharedThreadPool in the hash table of all created pools.
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SharedThreadPool(const nsCString& aName,
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nsIThreadPool* aPool);
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virtual ~SharedThreadPool();
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nsresult EnsureThreadLimitIsAtLeast(uint32_t aThreadLimit);
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// Name of mPool.
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const nsCString mName;
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// Thread pool being wrapped.
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nsCOMPtr<nsIThreadPool> mPool;
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// Refcount. We implement custom ref counting so that the thread pool is
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// shutdown in a threadsafe manner and singletonness is preserved.
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nsrefcnt mRefCnt;
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// mPool QI'd to nsIEventTarget. We cache this, so that we can use
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// NS_FORWARD_SAFE_NSIEVENTTARGET above.
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nsCOMPtr<nsIEventTarget> mEventTarget;
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};
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} // namespace mozilla
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#endif // SharedThreadPool_h_
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