87 lines
2.1 KiB
C++
87 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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/Function.h"
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#include "mozilla/mscom/COMApartmentRegion.h"
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#include "mozilla/mscom/Utils.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 <windows.h>
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namespace mozilla {
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namespace mscom {
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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
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{
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public:
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/**
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* This constructor just ensures that the MTA thread is up and running.
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*/
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EnsureMTA()
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{
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MOZ_ASSERT(NS_IsMainThread());
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nsCOMPtr<nsIThread> thread = GetMTAThread();
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MOZ_ASSERT(thread);
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}
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template <typename FuncT>
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EnsureMTA(const FuncT& aClosure)
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{
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MOZ_ASSERT(NS_IsMainThread());
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if (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<nsIThread> thread = GetMTAThread();
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MOZ_ASSERT(thread);
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HANDLE event = ::CreateEventW(nullptr, FALSE, FALSE, nullptr);
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if (!event) {
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return;
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}
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auto eventSetter = [&]() -> void {
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aClosure();
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::SetEvent(event);
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};
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nsresult rv =
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thread->Dispatch(NS_NewRunnableFunction(eventSetter), NS_DISPATCH_NORMAL);
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MOZ_ASSERT(NS_SUCCEEDED(rv));
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if (NS_WARN_IF(NS_FAILED(rv))) {
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::CloseHandle(event);
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return;
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}
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DWORD waitResult;
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while ((waitResult = ::WaitForSingleObjectEx(event, INFINITE, TRUE)) ==
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WAIT_IO_COMPLETION) {
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}
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MOZ_ASSERT(waitResult == WAIT_OBJECT_0);
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::CloseHandle(event);
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}
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private:
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static nsCOMPtr<nsIThread> GetMTAThread();
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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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