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8d83d5f8eb
Summary: I read my code and one thing stroke me: What if the same event emitter dispatches several events during the same event beat? In the previous implementation, only the first one will be delivered because the first `release` call consumes stored strong reference. So, I changed the API a bit to make this more explicit: we have `retain` & `release` methods and we have a getter that works (multiple times) only if the object was successfully retained. Reviewed By: sahrens Differential Revision: D13668147 fbshipit-source-id: c00af5f15bc7e30aa704d46bd23584b918b6f75a
67 lines
1.9 KiB
C++
67 lines
1.9 KiB
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 "EventTarget.h"
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namespace facebook {
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namespace react {
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using Tag = EventTarget::Tag;
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EventTarget::EventTarget(
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jsi::Runtime &runtime,
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const jsi::Value &instanceHandle,
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Tag tag)
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: weakInstanceHandle_(
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jsi::WeakObject(runtime, instanceHandle.asObject(runtime))),
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strongInstanceHandle_(jsi::Value::null()),
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tag_(tag) {}
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void EventTarget::setEnabled(bool enabled) const {
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enabled_ = enabled;
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}
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void EventTarget::retain(jsi::Runtime &runtime) const {
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if (!enabled_) {
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return;
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}
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strongInstanceHandle_ = weakInstanceHandle_.lock(runtime);
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// Having a `null` or `undefined` object here indicates that
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// `weakInstanceHandle_` was already deallocated. This should *not* happen by
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// design, and if it happens it's a severe problem. This basically means that
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// particular implementation of JSI was able to detect this inconsistency and
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// dealt with it, but some JSI implementation may not support this feature and
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// that case will lead to a crash in those environments.
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assert(!strongInstanceHandle_.isNull());
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assert(!strongInstanceHandle_.isUndefined());
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}
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void EventTarget::release(jsi::Runtime &runtime) const {
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// The method does not use `jsi::Runtime` reference.
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// It takes it only to ensure thread-safety (if the caller has the reference,
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// we are on a proper thread).
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strongInstanceHandle_ = jsi::Value::null();
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}
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jsi::Value EventTarget::getInstanceHandle(jsi::Runtime &runtime) const {
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if (strongInstanceHandle_.isNull()) {
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// The `instanceHandle` is not retained.
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return jsi::Value::null();
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}
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return jsi::Value(runtime, strongInstanceHandle_);
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}
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Tag EventTarget::getTag() const {
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return tag_;
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}
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} // namespace react
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} // namespace facebook
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