101 lines
3.8 KiB
C++
101 lines
3.8 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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#if !defined(AbstractThread_h_)
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#define AbstractThread_h_
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#include "nscore.h"
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#include "nsIRunnable.h"
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#include "nsISupportsImpl.h"
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#include "nsIThread.h"
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#include "mozilla/RefPtr.h"
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#include "mozilla/ThreadLocal.h"
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namespace mozilla {
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class TaskQueue;
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class TaskDispatcher;
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/*
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* We often want to run tasks on a target that guarantees that events will never
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* run in parallel. There are various target types that achieve this - namely
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* nsIThread and TaskQueue. Note that nsIThreadPool (which implements
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* nsIEventTarget) does not have this property, so we do not want to use
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* nsIEventTarget for this purpose. This class encapsulates the specifics of
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* the structures we might use here and provides a consistent interface.
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*
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* At present, the supported AbstractThread implementations are TaskQueue
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* and AbstractThread::MainThread. If you add support for another thread that is
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* not the MainThread, you'll need to figure out how to make it unique such that
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* comparing AbstractThread pointers is equivalent to comparing nsIThread pointers.
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*/
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class AbstractThread
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{
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public:
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// Returns the AbstractThread that the caller is currently running in, or null
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// if the caller is not running in an AbstractThread.
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static AbstractThread* GetCurrent() { return sCurrentThreadTLS.get(); }
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AbstractThread(bool aSupportsTailDispatch) : mSupportsTailDispatch(aSupportsTailDispatch) {}
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NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AbstractThread);
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enum DispatchFailureHandling { AssertDispatchSuccess, DontAssertDispatchSuccess };
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enum DispatchReason { NormalDispatch, TailDispatch };
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virtual void Dispatch(already_AddRefed<nsIRunnable> aRunnable,
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DispatchFailureHandling aHandling = AssertDispatchSuccess,
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DispatchReason aReason = NormalDispatch) = 0;
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virtual bool IsCurrentThreadIn() = 0;
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// Returns true if dispatch is generally reliable. This is used to guard
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// against FlushableTaskQueues, which should go away.
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virtual bool IsDispatchReliable() { return true; }
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// Returns a TaskDispatcher that will dispatch its tasks when the currently-
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// running tasks pops off the stack.
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//
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// May only be called when running within the it is invoked up, and only on
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// threads which support it.
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virtual TaskDispatcher& TailDispatcher() = 0;
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// Returns true if this supports the tail dispatcher.
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bool SupportsTailDispatch() const { return mSupportsTailDispatch; }
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// Returns true if this thread requires all dispatches originating from
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// aThread go through the tail dispatcher.
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bool RequiresTailDispatch(AbstractThread* aThread) const;
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virtual TaskQueue* AsTaskQueue() { MOZ_CRASH("Not a task queue!"); }
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virtual nsIThread* AsXPCOMThread() { MOZ_CRASH("Not an XPCOM thread!"); }
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// Convenience method for getting an AbstractThread for the main thread.
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static AbstractThread* MainThread();
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// Must be called exactly once during startup.
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static void InitStatics();
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void DispatchStateChange(already_AddRefed<nsIRunnable> aRunnable);
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static void DispatchDirectTask(already_AddRefed<nsIRunnable> aRunnable);
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protected:
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virtual ~AbstractThread() {}
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static ThreadLocal<AbstractThread*> sCurrentThreadTLS;
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// True if we want to require that every task dispatched from tasks running in
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// this queue go through our queue's tail dispatcher.
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const bool mSupportsTailDispatch;
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};
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already_AddRefed<AbstractThread> CreateXPCOMAbstractThreadWrapper(nsIThread* aThread,
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bool aRequireTailDispatch);
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} // namespace mozilla
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#endif
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