[英]My react event pooling pseudo example makes sense?
我可以检查有关反应中
event pooling
逻辑的实现吗?
我想知道event pooling
原理:)
当我深入研究响应文档时,我看到了event pooling
。
所以,我很好奇什么是event pooling
,我研究了它。
现在我意识到thread pooling
。 所以它的工作方式类似。 所以我做了一些伪event pooling
逻辑。
我想知道这有意义吗?
任何知道
event pooling
实现在哪里的人都会react
package。
请给我评论
EventPool 伪实现
class EventPool {
private static instance: EventPool;
private taskQueue: Event[] = [];
private constructor() {
this.taskQueue = [];
}
public static shared() {
if (!EventPool.instance) {
EventPool.instance = new EventPool();
}
return EventPool.instance;
}
enqueue = (event: Event) => {
this.taskQueue = this.taskQueue.concat(event);
};
dequeue = (currentTarget: any) => {
this.taskQueue = this.taskQueue.filter(
(event: Event) => event.currentTarget === currentTarget
);
};
clear() {
// This function called before or after render
// (Commit -> Render -> EventPool.shared().clear()) or (Commit -> EventPool.shared().clear() -> Render)
this.taskQueue = this.taskQueue.filter((event) => event.isDone === true);
}
}
关于persist
的事件伪实现
class Event {
persist = () => {
// This is executed before EventPool.shared.clear
EventPool.shared().dequeue(this);
};
}
这是SyntheticEvent
/ EventPool
模式的非常简单的示例。 显然,在现实生活中,更好地尊重事件的行为会有点复杂,但这个片段必须阐明一些概念。
class SyntheticEvent {
// all the following properties and methods are part of React's
// synthetic event, but we'll skip it here in favor of simplicity
// bubbles: boolean
// currentTarget: DOMEventTarget
// defaultPrevented: boolean
// eventPhase: number
// nativeEvent: DOMEvent
// preventDefault(): void {}
// isDefaultPrevented(): boolean { return true }
// stopPropagation(): void {}
// isPropagationStopped(): boolean { return true }
// target: DOMEventTarget
// timeStamp: number
// type: string
// for simplicity we'll consider here only 3 following properties
isTrusted: boolean
cancelable: boolean
persist: () => void
// this property helps to track status of each synthetic event
status: 'POOLED' | 'PERSISTED' | 'IN_USE'
constructor(status, onPersist: () => void) {
this.status = status;
this.persist = onPersist;
}
}
class EventPool {
private pool: SyntheticEvent[] = [];
constructor(initialPoolSize: number) {
// populating pool with pre-allocated events. We will try to re-use
// them as much as possible to reduce GC load
for(let i = 0; i < initialPoolSize; i++) {
this.allocateNewEvent();
}
}
pullEvent(nativeEvent): SyntheticEvent {
const syntheticEvent = this.getEventFromPool();
this.populateEvent(syntheticEvent, nativeEvent);
return syntheticEvent;
}
tryPushEvent(syntheticEvent: SyntheticEvent): void {
if(syntheticEvent.status !== 'PERSISTED') {
this.clearEvent(syntheticEvent);
}
}
private allocateNewEvent(): SyntheticEvent {
const newEvent = new SyntheticEvent( 'POOLED', () => {
newEvent.status = 'PERSISTED';
});
this.pool.push(newEvent);
return newEvent;
}
private getEventFromPool() {
let event = this.pool.find( e => e.status === 'POOLED' );
if(!event) {
event = this.allocateNewEvent();
}
return event;
}
/** Populates synthetic event with data from native event */
private populateEvent(syntheticEvent: SyntheticEvent, nativeEvent) {
syntheticEvent.status = 'IN_USE';
syntheticEvent.isTrusted = nativeEvent.isTrusted;
syntheticEvent.cancelable = nativeEvent.cancelable;
}
/** Sets all previously populated synthetic event fields to null for safe re-use */
private clearEvent(syntheticEvent: SyntheticEvent) {
syntheticEvent.status = 'POOLED';
syntheticEvent.isTrusted = null;
syntheticEvent.cancelable = null;
}
}
// Usage
const mainEventPool = new EventPool(2);
smth.onClick = nativeEvent => {
const syntheticEvent = mainEventPool.pullEvent(nativeEvent);
userDefinedOnClickHandler(syntheticEvent); // <-- on click handler defined by user
mainEventPool.tryPushEvent(syntheticEvent);
};
事件池——React 使用 SyntheticEvent,它是原生浏览器事件的包装器,因此它们在不同浏览器中具有一致的属性。 我们在任何 react-app 中拥有的事件处理程序实际上是传递 SyntheticEvent 的实例,除非我们使用 nativeEvent 属性来获取底层浏览器事件。
包装本机事件实例可能会导致性能问题,因为创建的每个合成事件包装器也需要在某些时候进行垃圾收集,这在 CPU 时间方面可能会很昂贵。
React 通过分配一个合成实例池来处理这个问题。 每当触发事件时,它都会从池中获取一个实例并填充其属性并重用它。 当事件处理程序完成运行时,所有属性都将被取消,合成事件实例被释放回池中。 因此,提高性能。
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