forked from mirrors/gecko-dev
d57c9498f6
This flag is not supported by most event targets and can have unexpected side effects (namely spinning a nested event loop). All consumers have been replaced with a new function which is more explicit about this side effect. Differential Revision: https://phabricator.services.mozilla.com/D173985
65 lines
2.1 KiB
C++
65 lines
2.1 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 nsThreadSyncDispatch_h_
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#define nsThreadSyncDispatch_h_
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#include "mozilla/Atomics.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/SpinEventLoopUntil.h"
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#include "nsThreadUtils.h"
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#include "LeakRefPtr.h"
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class nsThreadSyncDispatch : public mozilla::Runnable {
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public:
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nsThreadSyncDispatch(already_AddRefed<nsIEventTarget> aOrigin,
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already_AddRefed<nsIRunnable>&& aTask)
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: Runnable("nsThreadSyncDispatch"),
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mOrigin(aOrigin),
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mSyncTask(std::move(aTask)),
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mIsPending(true) {}
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bool IsPending() {
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// This is an atomic acquire on the origin thread.
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return mIsPending;
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}
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void SpinEventLoopUntilComplete(const nsACString& aVeryGoodReasonToDoThis) {
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mozilla::SpinEventLoopUntil(aVeryGoodReasonToDoThis,
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[&]() -> bool { return !IsPending(); });
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}
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private:
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NS_IMETHOD Run() override {
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if (nsCOMPtr<nsIRunnable> task = mSyncTask.take()) {
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MOZ_ASSERT(!mSyncTask);
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mozilla::DebugOnly<nsresult> result = task->Run();
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MOZ_ASSERT(NS_SUCCEEDED(result), "task in sync dispatch should not fail");
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// We must release the task here to ensure that when the original
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// thread is unblocked, this task has been released.
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task = nullptr;
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// This is an atomic release on the target thread.
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mIsPending = false;
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// unblock the origin thread
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mOrigin->Dispatch(this, NS_DISPATCH_IGNORE_BLOCK_DISPATCH);
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}
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return NS_OK;
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}
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nsCOMPtr<nsIEventTarget> mOrigin;
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// The task is leaked by default when Run() is not called, because
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// otherwise we may release it in an incorrect thread.
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mozilla::LeakRefPtr<nsIRunnable> mSyncTask;
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mozilla::Atomic<bool, mozilla::ReleaseAcquire> mIsPending;
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};
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#endif // nsThreadSyncDispatch_h_
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