зеркало из https://github.com/mozilla/gecko-dev.git
137 строки
4.2 KiB
C++
137 строки
4.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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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#include "AbstractThread.h"
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#include "MediaTaskQueue.h"
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#include "nsThreadUtils.h"
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#include "TaskDispatcher.h"
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#include "nsIAppShell.h"
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#include "nsWidgetsCID.h"
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#include "nsServiceManagerUtils.h"
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#include "mozilla/ClearOnShutdown.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/StaticPtr.h"
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#include "mozilla/unused.h"
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namespace mozilla {
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StaticRefPtr<AbstractThread> sMainThread;
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ThreadLocal<AbstractThread*> AbstractThread::sCurrentThreadTLS;
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static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);
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class XPCOMThreadWrapper : public AbstractThread
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{
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public:
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explicit XPCOMThreadWrapper(nsIThread* aTarget, bool aRequireTailDispatch)
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: AbstractThread(aRequireTailDispatch)
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, mTarget(aTarget)
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{
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// Our current mechanism of implementing tail dispatch is appshell-specific.
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// This is because a very similar mechanism already exists on the main
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// thread, and we want to avoid making event dispatch on the main thread
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// more complicated than it already is.
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//
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// If you need to use tail dispatch on other XPCOM threads, you'll need to
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// implement an nsIThreadObserver to fire the tail dispatcher at the
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// appropriate times.
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MOZ_ASSERT_IF(aRequireTailDispatch,
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NS_IsMainThread() && NS_GetCurrentThread() == aTarget);
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}
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virtual void Dispatch(already_AddRefed<nsIRunnable> aRunnable,
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DispatchFailureHandling aFailureHandling = AssertDispatchSuccess,
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DispatchReason aReason = NormalDispatch) override
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{
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nsCOMPtr<nsIRunnable> r = aRunnable;
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AbstractThread* currentThread;
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if (aReason != TailDispatch && (currentThread = GetCurrent()) && RequiresTailDispatch(currentThread)) {
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currentThread->TailDispatcher().AddTask(this, r.forget(), aFailureHandling);
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return;
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}
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nsresult rv = mTarget->Dispatch(r, NS_DISPATCH_NORMAL);
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MOZ_DIAGNOSTIC_ASSERT(aFailureHandling == DontAssertDispatchSuccess || NS_SUCCEEDED(rv));
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unused << rv;
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}
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virtual bool IsCurrentThreadIn() override
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{
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// Compare NSPR threads so that this works after shutdown when
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// NS_GetCurrentThread starts returning null.
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PRThread* thread = nullptr;
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mTarget->GetPRThread(&thread);
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bool in = PR_GetCurrentThread() == thread;
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MOZ_ASSERT(in == (GetCurrent() == this));
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return in;
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}
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void FireTailDispatcher()
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{
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MOZ_DIAGNOSTIC_ASSERT(mTailDispatcher.isSome());
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mTailDispatcher.ref().DrainDirectTasks();
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mTailDispatcher.reset();
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}
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virtual TaskDispatcher& TailDispatcher() override
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{
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MOZ_ASSERT(this == sMainThread); // See the comment in the constructor.
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MOZ_ASSERT(IsCurrentThreadIn());
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if (!mTailDispatcher.isSome()) {
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mTailDispatcher.emplace(/* aIsTailDispatcher = */ true);
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nsCOMPtr<nsIRunnable> event = NS_NewRunnableMethod(this, &XPCOMThreadWrapper::FireTailDispatcher);
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nsCOMPtr<nsIAppShell> appShell = do_GetService(kAppShellCID);
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appShell->RunInStableState(event);
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}
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return mTailDispatcher.ref();
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}
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virtual nsIThread* AsXPCOMThread() override { return mTarget; }
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private:
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nsRefPtr<nsIThread> mTarget;
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Maybe<AutoTaskDispatcher> mTailDispatcher;
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};
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bool
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AbstractThread::RequiresTailDispatch(AbstractThread* aThread) const
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{
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// We require tail dispatch if both the source and destination
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// threads support it.
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return SupportsTailDispatch() && aThread->SupportsTailDispatch();
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}
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AbstractThread*
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AbstractThread::MainThread()
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{
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MOZ_ASSERT(sMainThread);
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return sMainThread;
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}
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void
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AbstractThread::InitStatics()
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{
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MOZ_ASSERT(NS_IsMainThread());
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MOZ_ASSERT(!sMainThread);
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nsCOMPtr<nsIThread> mainThread;
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NS_GetMainThread(getter_AddRefs(mainThread));
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MOZ_DIAGNOSTIC_ASSERT(mainThread);
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sMainThread = new XPCOMThreadWrapper(mainThread.get(), /* aRequireTailDispatch = */ true);
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ClearOnShutdown(&sMainThread);
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if (!sCurrentThreadTLS.init()) {
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MOZ_CRASH();
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}
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sCurrentThreadTLS.set(sMainThread);
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}
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} // namespace mozilla
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