136 lines
5 KiB
C++
136 lines
5 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=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 https://mozilla.org/MPL/2.0/. */
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#ifndef TESTING_GTEST_MOZILLA_WAITFOR_H_
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#define TESTING_GTEST_MOZILLA_WAITFOR_H_
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#include "MediaEventSource.h"
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#include "mozilla/media/MediaUtils.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/MozPromise.h"
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#include "mozilla/ResultVariant.h"
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#include "mozilla/SpinEventLoopUntil.h"
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namespace mozilla {
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/**
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* Waits for an occurrence of aEvent on the current thread (by blocking it,
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* except tasks added to the event loop may run) and returns the event's
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* templated value, if it's non-void.
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*
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* The caller must be wary of eventloop issues, in
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* particular cases where we rely on a stable state runnable, but there is never
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* a task to trigger stable state. In such cases it is the responsibility of the
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* caller to create the needed tasks, as JS would. A noteworthy API that relies
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* on stable state is MediaTrackGraph::GetInstance.
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*/
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template <typename T>
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T WaitFor(MediaEventSource<T>& aEvent) {
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Maybe<T> value;
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MediaEventListener listener = aEvent.Connect(
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AbstractThread::GetCurrent(), [&](T aValue) { value = Some(aValue); });
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SpinEventLoopUntil<ProcessFailureBehavior::IgnoreAndContinue>(
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"WaitFor(MediaEventSource<T>& aEvent)"_ns,
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[&] { return value.isSome(); });
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listener.Disconnect();
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return value.value();
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}
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/**
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* Specialization of WaitFor<T> for void.
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*/
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void WaitFor(MediaEventSource<void>& aEvent);
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/**
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* Variant of WaitFor that blocks the caller until a MozPromise has either been
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* resolved or rejected.
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*/
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template <typename R, typename E, bool Exc>
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Result<R, E> WaitFor(const RefPtr<MozPromise<R, E, Exc>>& aPromise) {
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Maybe<R> success;
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Maybe<E> error;
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aPromise->Then(
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GetCurrentSerialEventTarget(), __func__,
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[&](R aResult) { success = Some(aResult); },
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[&](E aError) { error = Some(aError); });
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SpinEventLoopUntil<ProcessFailureBehavior::IgnoreAndContinue>(
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"WaitFor(const RefPtr<MozPromise<R, E, Exc>>& aPromise)"_ns,
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[&] { return success.isSome() || error.isSome(); });
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if (success.isSome()) {
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return success.extract();
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}
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return Err(error.extract());
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}
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/**
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* A variation of WaitFor that takes a callback to be called each time aEvent is
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* raised. Blocks the caller until the callback function returns true.
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*/
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template <typename... Args, typename CallbackFunction>
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void WaitUntil(MediaEventSource<Args...>& aEvent, CallbackFunction&& aF) {
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bool done = false;
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MediaEventListener listener =
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aEvent.Connect(AbstractThread::GetCurrent(), [&](Args... aValue) {
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if (!done) {
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done = aF(std::forward<Args>(aValue)...);
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}
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});
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SpinEventLoopUntil<ProcessFailureBehavior::IgnoreAndContinue>(
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"WaitUntil(MediaEventSource<Args...>& aEvent, CallbackFunction&& aF)"_ns,
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[&] { return done; });
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listener.Disconnect();
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}
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template <typename... Args>
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using TakeNPromise = MozPromise<std::vector<std::tuple<Args...>>, bool, true>;
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template <ListenerPolicy Lp, typename... Args>
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auto TakeN(MediaEventSourceImpl<Lp, Args...>& aEvent, size_t aN)
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-> RefPtr<TakeNPromise<Args...>> {
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using Storage = std::vector<std::tuple<Args...>>;
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using Promise = TakeNPromise<Args...>;
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using Values = media::Refcountable<Storage>;
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using Listener = media::Refcountable<MediaEventListener>;
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RefPtr<Values> values = MakeRefPtr<Values>();
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values->reserve(aN);
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RefPtr<Listener> listener = MakeRefPtr<Listener>();
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auto promise = InvokeAsync(
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AbstractThread::GetCurrent(), __func__, [values, aN]() mutable {
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SpinEventLoopUntil<ProcessFailureBehavior::IgnoreAndContinue>(
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"TakeN(MediaEventSourceImpl<Lp, Args...>& aEvent, size_t aN)"_ns,
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[&] { return values->size() == aN; });
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return Promise::CreateAndResolve(std::move(*values), __func__);
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});
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*listener = aEvent.Connect(AbstractThread::GetCurrent(),
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[values, listener, aN](Args... aValue) {
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values->push_back({aValue...});
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if (values->size() == aN) {
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listener->Disconnect();
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}
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});
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return promise;
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}
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/**
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* Helper that, given that canonicals have just been updated on the current
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* thread, will block its execution until mirrors and their watchers have
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* executed on aTarget.
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*/
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inline void WaitForMirrors(const RefPtr<nsISerialEventTarget>& aTarget) {
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Unused << WaitFor(InvokeAsync(aTarget, __func__, [] {
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return GenericPromise::CreateAndResolve(true, "WaitForMirrors resolver");
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}));
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}
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/**
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* Short form of WaitForMirrors that assumes mirrors are on the current thread
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* (like canonicals).
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*/
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inline void WaitForMirrors() { WaitForMirrors(GetCurrentSerialEventTarget()); }
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} // namespace mozilla
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#endif // TESTING_GTEST_MOZILLA_WAITFOR_H_
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