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chore: audit usages of bind()

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shirakaba
2022-12-21 16:10:04 +09:00
parent a87e828a64
commit 8b5efc1346
2 changed files with 27 additions and 26 deletions
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23
packages/core/data/dom-events/dom-event.ts
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@@ -369,11 +369,11 @@ export class DOMEvent implements Event {
//
// Creating it on the prototype and binding the context instead saves a
// further 30 nanoseconds per run of dispatchTo().
private onCurrentListenersMutation() {
private beforeCurrentListenersMutation() {
// Cloning the array via spread syntax is up to 180 nanoseconds
// faster per run than using Array.prototype.slice().
this.listenersLazyCopy = [...this.listenersLive];
this.listenersLive.onMutation = null;
this.listenersLive.beforeMutation = null;
}
// Taking multiple params instead of a single property bag saves 250
@@ -381,10 +381,10 @@ export class DOMEvent implements Event {
private handleEvent(data: EventData, isGlobal: boolean, phase: 0 | 1 | 2 | 3, removeEventListener: (eventName: string, callback?: any, thisArg?: any, capture?: boolean) => void, removeEventListenerContext: unknown) {
// Set a listener to clone the array just before any mutations.
//
// Lazy-binding this (binding it just before being called, rather than
// up-front) unexpectedly seems to slow things down - v8 may be
// optimising it for us or something.
this.listenersLive.onMutation = this.onCurrentListenersMutation.bind(this);
// Lazy-binding this (binding it at the time of calling, rather than
// eagerly) unexpectedly seems to slow things down - v8 may be applying
// some sort of optimisation or something.
this.listenersLive.beforeMutation = this.beforeCurrentListenersMutation.bind(this);
for (let i = this.listenersLazyCopy.length - 1; i >= 0; i--) {
const listener = this.listenersLazyCopy[i];
@@ -403,6 +403,13 @@ export class DOMEvent implements Event {
// We simply use a strict equality check here because we trust that
// the listeners provider will never allow two deeply-equal
// listeners into the array.
//
// This check costs 150 ns per dispatchTo(). I experimented with
// optimising this by building a Set of ListenerEntries that got
// removed during this handleEvent() (by introducing a method to
// MutationSensitiveArray called afterRemoval, similar to
// beforeMutation) to allow O(1) lookup, but it went 1000 ns slower
// in practice, so it stays!
if (!this.listenersLive.includes(listener)) {
continue;
}
@@ -415,6 +422,8 @@ export class DOMEvent implements Event {
}
if (once) {
// Calling with the context (rather than eagerly pre-binding it)
// saves about 100 nanoseconds per dispatchTo() call.
removeEventListener.call(removeEventListenerContext, this.type, callback, thisArg, capture);
}
@@ -443,7 +452,7 @@ export class DOMEvent implements Event {
// Make sure we clear the callback before we exit the function,
// otherwise we may wastefully clone the array on future mutations.
this.listenersLive.onMutation = null;
this.listenersLive.beforeMutation = null;
}
/**