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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
| commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
| tree | f435a8308119effd964b339f76abb83a57c29483 /xpcom/threads/SyncRunnable.h | |
| parent | Initial commit. (diff) | |
| download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip | |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'xpcom/threads/SyncRunnable.h')
| -rw-r--r-- | xpcom/threads/SyncRunnable.h | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/xpcom/threads/SyncRunnable.h b/xpcom/threads/SyncRunnable.h new file mode 100644 index 0000000000..77f82ba313 --- /dev/null +++ b/xpcom/threads/SyncRunnable.h @@ -0,0 +1,157 @@ +/* -*- 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 mozilla_SyncRunnable_h +#define mozilla_SyncRunnable_h + +#include <utility> + +#include "mozilla/AbstractThread.h" +#include "mozilla/Monitor.h" +#include "mozilla/dom/JSExecutionManager.h" +#include "nsThreadUtils.h" + +namespace mozilla { + +/** + * This class will wrap a nsIRunnable and dispatch it to the target thread + * synchronously. This is different from + * NS_DispatchAndSpinEventLoopUntilComplete: this class does not spin the event + * loop waiting for the event to be dispatched. This means that you don't risk + * reentrance from pending messages, but you must be sure that the target thread + * does not ever block on this thread, or else you will deadlock. + * + * Typical usage: + * RefPtr<SyncRunnable> sr = new SyncRunnable(new myrunnable...()); + * sr->DispatchToThread(t); + * + * We also provide convenience wrappers: + * SyncRunnable::DispatchToThread(pThread, new myrunnable...()); + * SyncRunnable::DispatchToThread(pThread, NS_NewRunnableFunction(...)); + * + */ +class SyncRunnable : public Runnable { + public: + explicit SyncRunnable(nsIRunnable* aRunnable) + : Runnable("SyncRunnable"), + mRunnable(aRunnable), + mMonitor("SyncRunnable"), + mDone(false) {} + + explicit SyncRunnable(already_AddRefed<nsIRunnable> aRunnable) + : Runnable("SyncRunnable"), + mRunnable(std::move(aRunnable)), + mMonitor("SyncRunnable"), + mDone(false) {} + + nsresult DispatchToThread(nsIEventTarget* aThread, + bool aForceDispatch = false) { + nsresult rv; + bool on; + + if (!aForceDispatch) { + rv = aThread->IsOnCurrentThread(&on); + MOZ_ASSERT(NS_SUCCEEDED(rv)); + if (NS_SUCCEEDED(rv) && on) { + mRunnable->Run(); + return NS_OK; + } + } + + rv = aThread->Dispatch(this, NS_DISPATCH_NORMAL); + if (NS_SUCCEEDED(rv)) { + mozilla::MonitorAutoLock lock(mMonitor); + // This could be synchronously dispatching to a thread currently waiting + // for JS execution clearance. Yield JS execution. + dom::AutoYieldJSThreadExecution yield; + + while (!mDone) { + lock.Wait(); + } + } + return rv; + } + + nsresult DispatchToThread(AbstractThread* aThread, + bool aForceDispatch = false) { + if (!aForceDispatch && aThread->IsCurrentThreadIn()) { + mRunnable->Run(); + return NS_OK; + } + + // Check we don't have tail dispatching here. Otherwise we will deadlock + // ourself when spinning the loop below. + MOZ_ASSERT(!aThread->RequiresTailDispatchFromCurrentThread()); + + nsresult rv = aThread->Dispatch(RefPtr<nsIRunnable>(this).forget()); + if (NS_SUCCEEDED(rv)) { + mozilla::MonitorAutoLock lock(mMonitor); + while (!mDone) { + lock.Wait(); + } + } + return rv; + } + + static nsresult DispatchToThread(nsIEventTarget* aThread, + nsIRunnable* aRunnable, + bool aForceDispatch = false) { + RefPtr<SyncRunnable> s(new SyncRunnable(aRunnable)); + return s->DispatchToThread(aThread, aForceDispatch); + } + + static nsresult DispatchToThread(AbstractThread* aThread, + nsIRunnable* aRunnable, + bool aForceDispatch = false) { + RefPtr<SyncRunnable> s(new SyncRunnable(aRunnable)); + return s->DispatchToThread(aThread, aForceDispatch); + } + + static nsresult DispatchToThread(nsIEventTarget* aThread, + already_AddRefed<nsIRunnable> aRunnable, + bool aForceDispatch = false) { + RefPtr<SyncRunnable> s(new SyncRunnable(std::move(aRunnable))); + return s->DispatchToThread(aThread, aForceDispatch); + } + + static nsresult DispatchToThread(AbstractThread* aThread, + already_AddRefed<nsIRunnable> aRunnable, + bool aForceDispatch = false) { + RefPtr<SyncRunnable> s(new SyncRunnable(std::move(aRunnable))); + return s->DispatchToThread(aThread, aForceDispatch); + } + + // These deleted overloads prevent accidentally (if harmlessly) double- + // wrapping SyncRunnable, which was previously a common anti-pattern. + static nsresult DispatchToThread(nsIEventTarget* aThread, + SyncRunnable* aRunnable, + bool aForceDispatch = false) = delete; + static nsresult DispatchToThread(AbstractThread* aThread, + SyncRunnable* aRunnable, + bool aForceDispatch = false) = delete; + + protected: + NS_IMETHOD Run() override { + mRunnable->Run(); + + mozilla::MonitorAutoLock lock(mMonitor); + MOZ_ASSERT(!mDone); + + mDone = true; + mMonitor.Notify(); + + return NS_OK; + } + + private: + nsCOMPtr<nsIRunnable> mRunnable; + mozilla::Monitor mMonitor; + bool mDone MOZ_GUARDED_BY(mMonitor); +}; + +} // namespace mozilla + +#endif // mozilla_SyncRunnable_h |