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/* -*- 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/. */
#ifndef nsThreadSyncDispatch_h_
#define nsThreadSyncDispatch_h_
#include "mozilla/Atomics.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/SpinEventLoopUntil.h"
#include "nsThreadUtils.h"
#include "LeakRefPtr.h"
class nsThreadSyncDispatch : public mozilla::Runnable {
public:
nsThreadSyncDispatch(already_AddRefed<nsIEventTarget> aOrigin,
already_AddRefed<nsIRunnable>&& aTask)
: Runnable("nsThreadSyncDispatch"),
mOrigin(aOrigin),
mSyncTask(std::move(aTask)),
mIsPending(true) {}
bool IsPending() {
// This is an atomic acquire on the origin thread.
return mIsPending;
}
void SpinEventLoopUntilComplete(const nsACString& aVeryGoodReasonToDoThis) {
mozilla::SpinEventLoopUntil(aVeryGoodReasonToDoThis,
[&]() -> bool { return !IsPending(); });
}
private:
NS_IMETHOD Run() override {
if (nsCOMPtr<nsIRunnable> task = mSyncTask.take()) {
MOZ_ASSERT(!mSyncTask);
mozilla::DebugOnly<nsresult> result = task->Run();
MOZ_ASSERT(NS_SUCCEEDED(result), "task in sync dispatch should not fail");
// We must release the task here to ensure that when the original
// thread is unblocked, this task has been released.
task = nullptr;
// This is an atomic release on the target thread.
mIsPending = false;
// unblock the origin thread
mOrigin->Dispatch(this, NS_DISPATCH_IGNORE_BLOCK_DISPATCH);
}
return NS_OK;
}
nsCOMPtr<nsIEventTarget> mOrigin;
// The task is leaked by default when Run() is not called, because
// otherwise we may release it in an incorrect thread.
mozilla::LeakRefPtr<nsIRunnable> mSyncTask;
mozilla::Atomic<bool, mozilla::ReleaseAcquire> mIsPending;
};
#endif // nsThreadSyncDispatch_h_
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