Files
welshman/packages/lib/Worker.ts
T
2024-03-26 11:35:34 -07:00

72 lines
1.5 KiB
TypeScript

const ANY = Symbol("worker/ANY")
export type WorkerOpts<T> = {
getKey?: (x: T) => any
shouldDefer?: (x: T) => boolean
}
export class Worker<T> {
buffer: T[] = []
handlers: Map<any, Array<(x: T) => void>> = new Map()
timeout: number | undefined
constructor(readonly opts: WorkerOpts<T> = {}) {}
#doWork = async () => {
for (let i = 0; i < 50; i++) {
if (this.buffer.length === 0) {
break
}
// Pop the buffer one at a time so handle can modify the queue
const [message] = this.buffer.splice(0, 1)
if (this.opts.shouldDefer?.(message)) {
this.buffer.push(message)
} else {
for (const handler of this.handlers.get(ANY) || []) {
await handler(message)
}
if (this.opts.getKey) {
const k = this.opts.getKey(message)
for (const handler of this.handlers.get(k) || []) {
await handler(message)
}
}
}
}
this.timeout = undefined
this.#enqueueWork()
}
#enqueueWork = () => {
if (!this.timeout && this.buffer.length > 0) {
this.timeout = setTimeout(this.#doWork, 50)
}
}
push = (message: T) => {
this.buffer.push(message)
this.#enqueueWork()
}
addHandler = (k: any, handler: (message: T) => void) => {
this.handlers.set(k, (this.handlers.get(k) || []).concat(handler))
}
addGlobalHandler = (handler: (message: T) => void) => {
this.addHandler(ANY, handler)
}
clear() {
this.buffer = []
}
stop() {
clearTimeout(this.timeout)
}
}