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https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Valentin Shergin
c80192c2ab
Summary: The purpose of `EventBeat` is handling an asynchronous callback to itself which is being delivered on some different thread. That brings a challenge of ensuring that the `EventBeat` object stays valid during the timeframe of callback execution. The concept of Owner helps with that. The owner is a shared pointer that retains (probably indirectly) the `EventBeat` object. To ensure the correctness of the call, `EventBeat` retains the owner (practically creating a retain cycle) during executing the callback. In case if the pointer to the owner already null, `EventBeat` skips executing the callback. It's impossible to retain itself directly or refer to the shared pointer to itself from a constructor. `OwnerBox` is designed to work around this issue; it allows to store the pointer later, right after the creation of some other object that owns an `EventBeat`. Reviewed By: JoshuaGross Differential Revision: D17128549 fbshipit-source-id: 7ed34fd865430975157fd362f51c4a3d64214430
38 lines
922 B
C++
38 lines
922 B
C++
// Copyright (c) Facebook, Inc. and its affiliates.
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// This source code is licensed under the MIT license found in the
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// LICENSE file in the root directory of this source tree.
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#pragma once
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#include <CoreFoundation/CFRunLoop.h>
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#include <CoreFoundation/CoreFoundation.h>
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#include <react/core/EventBeat.h>
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#include <react/utils/RuntimeExecutor.h>
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namespace facebook {
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namespace react {
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/*
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* Event beat associated with main run loop cycle.
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* The callback is always called on the main thread.
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*/
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class MainRunLoopEventBeat final : public EventBeat {
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public:
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MainRunLoopEventBeat(
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EventBeat::SharedOwnerBox const &ownerBox,
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RuntimeExecutor runtimeExecutor);
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~MainRunLoopEventBeat();
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void induce() const override;
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private:
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void lockExecutorAndBeat() const;
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const RuntimeExecutor runtimeExecutor_;
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CFRunLoopObserverRef mainRunLoopObserver_;
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};
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} // namespace react
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} // namespace facebook
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