rvx/dist/es/async/queue.js

A signal based rendering library

import { teardown } from "../core/lifecycle.js";
export class Queue {
    #queue = [];
    #blocked = -1;
    #controller = undefined;
    #running = undefined;
    constructor() {
        teardown(() => this.#abort());
    }
    #abort() {
        const queue = this.#queue;
        while (queue.length > 0 && !queue[0].blocking) {
            queue.shift();
            this.#blocked--;
        }
        this.#controller?.abort();
    }
    #run() {
        if (this.#running === undefined) {
            this.#running = (async () => {
                let task;
                while (task = this.#queue.shift()) {
                    this.#blocked--;
                    if (task.blocking) {
                        try {
                            task.resolve(await task.task());
                        }
                        catch (error) {
                            task.reject(error);
                        }
                    }
                    else {
                        const controller = new AbortController();
                        this.#controller = controller;
                        try {
                            await task.task(controller.signal);
                        }
                        catch (error) {
                            void Promise.reject(error);
                        }
                        this.#controller = undefined;
                    }
                }
                this.#blocked--;
                this.#running = undefined;
            })();
        }
    }
    sideEffect(task) {
        if (this.#blocked >= 0) {
            return;
        }
        this.#abort();
        this.#queue.push({ blocking: false, task, resolve: undefined, reject: undefined });
        this.#run();
    }
    block(task) {
        return new Promise((resolve, reject) => {
            this.#abort();
            this.#blocked = this.#queue.push({ blocking: true, task, resolve, reject });
            this.#run();
        });
    }
}
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