зеркало из https://github.com/mozilla/gecko-dev.git
130 строки
3.7 KiB
C++
130 строки
3.7 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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#ifndef mozilla_mscom_EnsureMTA_h
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#define mozilla_mscom_EnsureMTA_h
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#include "MainThreadUtils.h"
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#include "mozilla/Attributes.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/MozPromise.h"
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#include "mozilla/Unused.h"
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#include "mozilla/mscom/AgileReference.h"
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#include "mozilla/mscom/Utils.h"
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#include "mozilla/RefPtr.h"
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#include "nsCOMPtr.h"
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#include "nsIThread.h"
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#include "nsThreadUtils.h"
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#include "nsWindowsHelpers.h"
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#include <windows.h>
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namespace mozilla {
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namespace mscom {
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namespace detail {
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// Forward declarations
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template <typename T>
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struct MTADelete;
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template <typename T>
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struct MTARelease;
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template <typename T>
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struct MTAReleaseInChildProcess;
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struct PreservedStreamDeleter;
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} // namespace detail
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class ProcessRuntime;
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// This class is OK to use as a temporary on the stack.
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class MOZ_STACK_CLASS EnsureMTA final {
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public:
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enum class Option {
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Default,
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// Forcibly dispatch to the thread returned by GetPersistentMTAThread(),
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// even if the current thread is already inside a MTA.
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ForceDispatchToPersistentThread,
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};
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/**
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* Synchronously run |aClosure| on a thread living in the COM multithreaded
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* apartment. If the current thread lives inside the COM MTA, then it runs
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* |aClosure| immediately unless |aOpt| ==
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* Option::ForceDispatchToPersistentThread.
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*/
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template <typename FuncT>
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explicit EnsureMTA(FuncT&& aClosure, Option aOpt = Option::Default) {
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if (aOpt != Option::ForceDispatchToPersistentThread &&
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IsCurrentThreadMTA()) {
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// We're already on the MTA, we can run aClosure directly
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aClosure();
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return;
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}
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// In this case we need to run aClosure on a background thread in the MTA
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nsCOMPtr<nsIRunnable> runnable(
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NS_NewRunnableFunction("EnsureMTA::EnsureMTA", std::move(aClosure)));
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SyncDispatch(std::move(runnable), aOpt);
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}
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private:
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static nsCOMPtr<nsIThread> GetPersistentMTAThread();
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static void SyncDispatch(nsCOMPtr<nsIRunnable>&& aRunnable, Option aOpt);
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static void SyncDispatchToPersistentThread(nsIRunnable* aRunnable);
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// The following function is private in order to force any consumers to be
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// declared as friends of EnsureMTA. The intention is to prevent
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// AsyncOperation from becoming some kind of free-for-all mechanism for
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// asynchronously executing work on a background thread.
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template <typename FuncT>
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static void AsyncOperation(FuncT&& aClosure) {
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if (IsCurrentThreadMTA()) {
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aClosure();
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return;
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}
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nsCOMPtr<nsIThread> thread(GetPersistentMTAThread());
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MOZ_ASSERT(thread);
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if (!thread) {
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return;
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}
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DebugOnly<nsresult> rv = thread->Dispatch(
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NS_NewRunnableFunction("mscom::EnsureMTA::AsyncOperation",
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std::move(aClosure)),
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NS_DISPATCH_NORMAL);
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MOZ_ASSERT(NS_SUCCEEDED(rv));
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}
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/**
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* This constructor just ensures that the MTA is up and running. This should
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* only be called by ProcessRuntime.
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*/
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EnsureMTA();
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friend class mozilla::mscom::ProcessRuntime;
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template <typename T>
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friend struct mozilla::mscom::detail::MTADelete;
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template <typename T>
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friend struct mozilla::mscom::detail::MTARelease;
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template <typename T>
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friend struct mozilla::mscom::detail::MTAReleaseInChildProcess;
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friend struct mozilla::mscom::detail::PreservedStreamDeleter;
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};
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} // namespace mscom
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} // namespace mozilla
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#endif // mozilla_mscom_EnsureMTA_h
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