michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim:set ts=2 sw=2 sts=2 et cindent: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef SharedThreadPool_h_
michael@0: #define SharedThreadPool_h_
michael@0: 
michael@0: #include <queue>
michael@0: #include "mozilla/RefPtr.h"
michael@0: #include "nsThreadUtils.h"
michael@0: #include "nsIThreadPool.h"
michael@0: #include "nsISupports.h"
michael@0: #include "nsISupportsImpl.h"
michael@0: #include "nsCOMPtr.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: // Wrapper that makes an nsIThreadPool a singleton, and provides a
michael@0: // consistent threadsafe interface to get instances. Callers simply get a
michael@0: // SharedThreadPool by the name of its nsIThreadPool. All get requests of
michael@0: // the same name get the same SharedThreadPool. Users must store a reference
michael@0: // to the pool, and when the last reference to a SharedThreadPool is dropped
michael@0: // the pool is shutdown and deleted. Users aren't required to manually
michael@0: // shutdown the pool, and can release references on any thread. On Windows
michael@0: // all threads in the pool have MSCOM initialized with COINIT_MULTITHREADED.
michael@0: class SharedThreadPool : public nsIThreadPool
michael@0: {
michael@0: public:
michael@0: 
michael@0:   // Gets (possibly creating) the shared thread pool singleton instance with
michael@0:   // thread pool named aName.
michael@0:   // *Must* be called on the main thread.
michael@0:   static TemporaryRef<SharedThreadPool> Get(const nsCString& aName,
michael@0:                                             uint32_t aThreadLimit = 4);
michael@0: 
michael@0:   // Spins the event loop until all thread pools are shutdown.
michael@0:   // *Must* be called on the main thread.
michael@0:   static void SpinUntilShutdown();
michael@0: 
michael@0:   // We implement custom threadsafe AddRef/Release pair, that destroys the
michael@0:   // the shared pool singleton when the refcount drops to 0. The addref/release
michael@0:   // are implemented using locking, so it's not recommended that you use them
michael@0:   // in a tight loop.
michael@0:   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr);
michael@0:   NS_IMETHOD_(MozExternalRefCountType) AddRef(void);
michael@0:   NS_IMETHOD_(MozExternalRefCountType) Release(void);
michael@0: 
michael@0:   // Forward behaviour to wrapped thread pool implementation.
michael@0:   NS_FORWARD_SAFE_NSITHREADPOOL(mPool);
michael@0:   NS_FORWARD_SAFE_NSIEVENTTARGET(GetEventTarget());
michael@0: 
michael@0:   nsIEventTarget* GetEventTarget() {
michael@0:     return mEventTarget;
michael@0:   }
michael@0: 
michael@0: private:
michael@0: 
michael@0:   // Creates necessary statics.
michael@0:   // Main thread only.
michael@0:   static void EnsureInitialized();
michael@0: 
michael@0:   // Creates a singleton SharedThreadPool wrapper around aPool.
michael@0:   // aName is the name of the aPool, and is used to lookup the
michael@0:   // SharedThreadPool in the hash table of all created pools.
michael@0:   SharedThreadPool(const nsCString& aName,
michael@0:                    nsIThreadPool* aPool);
michael@0:   virtual ~SharedThreadPool();
michael@0: 
michael@0:   nsresult EnsureThreadLimitIsAtLeast(uint32_t aThreadLimit);
michael@0: 
michael@0:   // Name of mPool.
michael@0:   const nsCString mName;
michael@0: 
michael@0:   // Thread pool being wrapped.
michael@0:   nsCOMPtr<nsIThreadPool> mPool;
michael@0: 
michael@0:   // Refcount. We implement custom ref counting so that the thread pool is
michael@0:   // shutdown in a threadsafe manner and singletonness is preserved.
michael@0:   nsrefcnt mRefCnt;
michael@0: 
michael@0:   // mPool QI'd to nsIEventTarget. We cache this, so that we can use
michael@0:   // NS_FORWARD_SAFE_NSIEVENTTARGET above.
michael@0:   nsCOMPtr<nsIEventTarget> mEventTarget;
michael@0: };
michael@0: 
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // SharedThreadPool_h_