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Diffstat (limited to 'ipc/mscom/EnsureMTA.cpp')
| -rw-r--r-- | ipc/mscom/EnsureMTA.cpp | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/ipc/mscom/EnsureMTA.cpp b/ipc/mscom/EnsureMTA.cpp new file mode 100644 index 0000000000..49d8446fa2 --- /dev/null +++ b/ipc/mscom/EnsureMTA.cpp @@ -0,0 +1,189 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "mozilla/mscom/EnsureMTA.h" + +#include "mozilla/Assertions.h" +#include "mozilla/ClearOnShutdown.h" +#include "mozilla/DebugOnly.h" +#include "mozilla/mscom/COMWrappers.h" +#include "mozilla/mscom/ProcessRuntime.h" +#include "mozilla/mscom/Utils.h" +#include "mozilla/SchedulerGroup.h" +#include "mozilla/StaticLocalPtr.h" +#include "nsThreadManager.h" +#include "nsThreadUtils.h" + +#include "private/pprthred.h" + +namespace { + +class EnterMTARunnable : public mozilla::Runnable { + public: + EnterMTARunnable() : mozilla::Runnable("EnterMTARunnable") {} + NS_IMETHOD Run() override { + mozilla::DebugOnly<HRESULT> hr = + mozilla::mscom::wrapped::CoInitializeEx(nullptr, COINIT_MULTITHREADED); + MOZ_ASSERT(SUCCEEDED(hr)); + return NS_OK; + } +}; + +class BackgroundMTAData { + public: + BackgroundMTAData() { + nsCOMPtr<nsIRunnable> runnable = new EnterMTARunnable(); + mozilla::DebugOnly<nsresult> rv = NS_NewNamedThread( + "COM MTA", getter_AddRefs(mThread), runnable.forget()); + NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "NS_NewNamedThread failed"); + MOZ_ASSERT(NS_SUCCEEDED(rv)); + } + + ~BackgroundMTAData() { + if (mThread) { + mThread->Dispatch( + NS_NewRunnableFunction("BackgroundMTAData::~BackgroundMTAData", + &mozilla::mscom::wrapped::CoUninitialize), + NS_DISPATCH_NORMAL); + mThread->Shutdown(); + } + } + + nsCOMPtr<nsIThread> GetThread() const { return mThread; } + + private: + nsCOMPtr<nsIThread> mThread; +}; + +} // anonymous namespace + +namespace mozilla { +namespace mscom { + +EnsureMTA::EnsureMTA() { + MOZ_ASSERT(NS_IsMainThread()); + + // It is possible that we're running so early that we might need to start + // the thread manager ourselves. We do this here to guarantee that we have + // the ability to start the persistent MTA thread at any moment beyond this + // point. + nsresult rv = nsThreadManager::get().Init(); + // We intentionally don't check rv unless we need it when + // CoIncremementMTAUsage is unavailable. + + // Calling this function initializes the MTA without needing to explicitly + // create a thread and call CoInitializeEx to do it. + // We don't retain the cookie because once we've incremented the MTA, we + // leave it that way for the lifetime of the process. + CO_MTA_USAGE_COOKIE mtaCookie = nullptr; + HRESULT hr = wrapped::CoIncrementMTAUsage(&mtaCookie); + if (SUCCEEDED(hr)) { + if (NS_SUCCEEDED(rv)) { + // Start the persistent MTA thread (mostly) asynchronously. + Unused << GetPersistentMTAThread(); + } + + return; + } + + // In the fallback case, we simply initialize our persistent MTA thread. + + // Make sure thread manager init succeeded before trying to initialize the + // persistent MTA thread. + MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv)); + if (NS_FAILED(rv)) { + return; + } + + // Before proceeding any further, pump a runnable through the persistent MTA + // thread to ensure that it is up and running and has finished initializing + // the multi-threaded apartment. + nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction( + "EnsureMTA::EnsureMTA()", + []() { MOZ_RELEASE_ASSERT(IsCurrentThreadExplicitMTA()); })); + SyncDispatchToPersistentThread(runnable); +} + +/* static */ +nsCOMPtr<nsIThread> EnsureMTA::GetPersistentMTAThread() { + static StaticLocalAutoPtr<BackgroundMTAData> sMTAData( + []() -> BackgroundMTAData* { + BackgroundMTAData* bgData = new BackgroundMTAData(); + + auto setClearOnShutdown = [ptr = &sMTAData]() -> void { + ClearOnShutdown(ptr, ShutdownPhase::XPCOMShutdownThreads); + }; + + if (NS_IsMainThread()) { + setClearOnShutdown(); + return bgData; + } + + SchedulerGroup::Dispatch( + NS_NewRunnableFunction("mscom::EnsureMTA::GetPersistentMTAThread", + std::move(setClearOnShutdown))); + + return bgData; + }()); + + MOZ_ASSERT(sMTAData); + + return sMTAData->GetThread(); +} + +/* static */ +void EnsureMTA::SyncDispatchToPersistentThread(nsIRunnable* aRunnable) { + nsCOMPtr<nsIThread> thread(GetPersistentMTAThread()); + MOZ_ASSERT(thread); + if (!thread) { + return; + } + + // Note that, due to APC dispatch, we might reenter this function while we + // wait on this event. We therefore need a unique event object for each + // entry into this function. If perf becomes an issue then we will want to + // maintain an array of events where the Nth event is unique to the Nth + // reentry. + nsAutoHandle event(::CreateEventW(nullptr, FALSE, FALSE, nullptr)); + if (!event) { + return; + } + + HANDLE eventHandle = event.get(); + auto eventSetter = [&aRunnable, eventHandle]() -> void { + aRunnable->Run(); + ::SetEvent(eventHandle); + }; + + nsresult rv = thread->Dispatch( + NS_NewRunnableFunction("mscom::EnsureMTA::SyncDispatchToPersistentThread", + std::move(eventSetter)), + NS_DISPATCH_NORMAL); + MOZ_ASSERT(NS_SUCCEEDED(rv)); + if (NS_FAILED(rv)) { + return; + } + + AUTO_PROFILER_THREAD_SLEEP; + DWORD waitResult; + while ((waitResult = ::WaitForSingleObjectEx(event, INFINITE, FALSE)) == + WAIT_IO_COMPLETION) { + } + MOZ_ASSERT(waitResult == WAIT_OBJECT_0); +} + +/** + * While this function currently appears to be redundant, it may become more + * sophisticated in the future. For example, we could optionally dispatch to an + * MTA context if we wanted to utilize the MTA thread pool. + */ +/* static */ +void EnsureMTA::SyncDispatch(nsCOMPtr<nsIRunnable>&& aRunnable, Option aOpt) { + SyncDispatchToPersistentThread(aRunnable); +} + +} // namespace mscom +} // namespace mozilla |