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https://github.com/facebook/react-native.git
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Valentin SherginandFacebook Github Bot
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
41 lines
800 B
C++
41 lines
800 B
C++
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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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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*/
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#include "EventBeat.h"
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namespace facebook {
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namespace react {
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EventBeat::EventBeat(SharedOwnerBox const &ownerBox) : ownerBox_(ownerBox) {}
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void EventBeat::request() const {
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isRequested_ = true;
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}
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void EventBeat::beat(jsi::Runtime &runtime) const {
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if (!this->isRequested_) {
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return;
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}
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isRequested_ = false;
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if (beatCallback_) {
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beatCallback_(runtime);
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}
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}
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void EventBeat::induce() const {
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// Default implementation does nothing.
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}
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void EventBeat::setBeatCallback(const BeatCallback &beatCallback) {
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beatCallback_ = beatCallback;
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}
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} // namespace react
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} // namespace facebook
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