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https://github.com/status-im/react-native.git
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08c404d293
Summary: While working with `RCTEventEmitter` I noticed that if an event is emitted before `_listenerCount` is updated, it will not go through because the listeners count hasn't been updated. Moving the count update before the invokation of `startObserving` and `stopObserving` fixes the issue. Same way if you remove the last listener and an event is fired before the count is updated (while it shouldn't be fired). **Test plan (required)** An easy test to demonstrate it is to implement `startObserving` to synchronously fire an event. Without the change, a warning is thrown, with the change, the event is fired. Not very strong on Obj-C here and I didn't know how to mock out the native stuff. Would be glad to write a failing unit test tho :) Closes https://github.com/facebook/react-native/pull/11907 Differential Revision: D4738965 Pulled By: javache fbshipit-source-id: cf175051be5b9c5de761d3dcd290560e1639b05e
99 lines
2.5 KiB
Objective-C
99 lines
2.5 KiB
Objective-C
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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#import "RCTEventEmitter.h"
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#import "RCTAssert.h"
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#import "RCTUtils.h"
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#import "RCTLog.h"
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@implementation RCTEventEmitter
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{
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NSInteger _listenerCount;
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}
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+ (NSString *)moduleName
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{
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return @"";
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}
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+ (void)initialize
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{
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if (self != [RCTEventEmitter class]) {
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RCTAssert(RCTClassOverridesInstanceMethod(self, @selector(supportedEvents)),
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@"You must override the `supportedEvents` method of %@", self);
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}
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}
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- (NSArray<NSString *> *)supportedEvents
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{
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return nil;
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}
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- (void)sendEventWithName:(NSString *)eventName body:(id)body
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{
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RCTAssert(_bridge != nil, @"bridge is not set. This is probably because you've "
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"explicitly synthesized the bridge in %@, even though it's inherited "
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"from RCTEventEmitter.", [self class]);
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if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
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RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
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eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
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}
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if (_listenerCount > 0) {
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[_bridge enqueueJSCall:@"RCTDeviceEventEmitter"
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method:@"emit"
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args:body ? @[eventName, body] : @[eventName]
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completion:NULL];
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} else {
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RCTLogWarn(@"Sending `%@` with no listeners registered.", eventName);
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}
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}
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- (void)startObserving
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{
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// Does nothing
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}
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- (void)stopObserving
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{
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// Does nothing
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}
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- (void)dealloc
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{
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if (_listenerCount > 0) {
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[self stopObserving];
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}
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}
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RCT_EXPORT_METHOD(addListener:(NSString *)eventName)
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{
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if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
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RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
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eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
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}
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_listenerCount++;
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if (_listenerCount == 1) {
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[self startObserving];
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}
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}
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RCT_EXPORT_METHOD(removeListeners:(NSInteger)count)
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{
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if (RCT_DEBUG && count > _listenerCount) {
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RCTLogError(@"Attempted to remove more %@ listeners than added", [self class]);
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}
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_listenerCount = MAX(_listenerCount - count, 0);
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if (_listenerCount == 0) {
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[self stopObserving];
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}
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}
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@end
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