1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/SharedThreadPool.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,90 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim:set ts=2 sw=2 sts=2 et cindent: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef SharedThreadPool_h_
1.11 +#define SharedThreadPool_h_
1.12 +
1.13 +#include <queue>
1.14 +#include "mozilla/RefPtr.h"
1.15 +#include "nsThreadUtils.h"
1.16 +#include "nsIThreadPool.h"
1.17 +#include "nsISupports.h"
1.18 +#include "nsISupportsImpl.h"
1.19 +#include "nsCOMPtr.h"
1.20 +
1.21 +namespace mozilla {
1.22 +
1.23 +// Wrapper that makes an nsIThreadPool a singleton, and provides a
1.24 +// consistent threadsafe interface to get instances. Callers simply get a
1.25 +// SharedThreadPool by the name of its nsIThreadPool. All get requests of
1.26 +// the same name get the same SharedThreadPool. Users must store a reference
1.27 +// to the pool, and when the last reference to a SharedThreadPool is dropped
1.28 +// the pool is shutdown and deleted. Users aren't required to manually
1.29 +// shutdown the pool, and can release references on any thread. On Windows
1.30 +// all threads in the pool have MSCOM initialized with COINIT_MULTITHREADED.
1.31 +class SharedThreadPool : public nsIThreadPool
1.32 +{
1.33 +public:
1.34 +
1.35 + // Gets (possibly creating) the shared thread pool singleton instance with
1.36 + // thread pool named aName.
1.37 + // *Must* be called on the main thread.
1.38 + static TemporaryRef<SharedThreadPool> Get(const nsCString& aName,
1.39 + uint32_t aThreadLimit = 4);
1.40 +
1.41 + // Spins the event loop until all thread pools are shutdown.
1.42 + // *Must* be called on the main thread.
1.43 + static void SpinUntilShutdown();
1.44 +
1.45 + // We implement custom threadsafe AddRef/Release pair, that destroys the
1.46 + // the shared pool singleton when the refcount drops to 0. The addref/release
1.47 + // are implemented using locking, so it's not recommended that you use them
1.48 + // in a tight loop.
1.49 + NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr);
1.50 + NS_IMETHOD_(MozExternalRefCountType) AddRef(void);
1.51 + NS_IMETHOD_(MozExternalRefCountType) Release(void);
1.52 +
1.53 + // Forward behaviour to wrapped thread pool implementation.
1.54 + NS_FORWARD_SAFE_NSITHREADPOOL(mPool);
1.55 + NS_FORWARD_SAFE_NSIEVENTTARGET(GetEventTarget());
1.56 +
1.57 + nsIEventTarget* GetEventTarget() {
1.58 + return mEventTarget;
1.59 + }
1.60 +
1.61 +private:
1.62 +
1.63 + // Creates necessary statics.
1.64 + // Main thread only.
1.65 + static void EnsureInitialized();
1.66 +
1.67 + // Creates a singleton SharedThreadPool wrapper around aPool.
1.68 + // aName is the name of the aPool, and is used to lookup the
1.69 + // SharedThreadPool in the hash table of all created pools.
1.70 + SharedThreadPool(const nsCString& aName,
1.71 + nsIThreadPool* aPool);
1.72 + virtual ~SharedThreadPool();
1.73 +
1.74 + nsresult EnsureThreadLimitIsAtLeast(uint32_t aThreadLimit);
1.75 +
1.76 + // Name of mPool.
1.77 + const nsCString mName;
1.78 +
1.79 + // Thread pool being wrapped.
1.80 + nsCOMPtr<nsIThreadPool> mPool;
1.81 +
1.82 + // Refcount. We implement custom ref counting so that the thread pool is
1.83 + // shutdown in a threadsafe manner and singletonness is preserved.
1.84 + nsrefcnt mRefCnt;
1.85 +
1.86 + // mPool QI'd to nsIEventTarget. We cache this, so that we can use
1.87 + // NS_FORWARD_SAFE_NSIEVENTTARGET above.
1.88 + nsCOMPtr<nsIEventTarget> mEventTarget;
1.89 +};
1.90 +
1.91 +} // namespace mozilla
1.92 +
1.93 +#endif // SharedThreadPool_h_
