osrscachereader/src/cacheReader/WorkerPool.js

Read Old-School Runescape Cache files

import Worker from "web-worker";

export default class WorkerPool {
    workers;
    workQueue = new Array();
    promises = new Array();

    constructor(size = 8) {
        this.workers = new Array(size).fill().map((x, i) => ({
            id: i,
            worker: new Worker(new URL("./worker.cjs", import.meta.url)),
            active: false,
        }));

        this.workers.forEach(
            (workerObject) =>
                (workerObject.worker.onmessage = (event) => {
                    const data = event.data;
                    data.decompressedData = new Uint8Array(data.decompressedData);

                    const promise = this.promises[data.index.id][data.archiveId];
                    promise.resolve(data);

                    this.promises[data.index.id][data.archiveId] = undefined;

                    if (this.workQueue.length != 0) {
                        const newWork = this.workQueue.shift();
                        workerObject.worker.postMessage(newWork, [newWork.compressedData]);
                    } else {
                        workerObject.active = false;
                    }
                }),
        );
    }

    doWork(index, segment, archiveId, compressedData, key) {
        if (this.promises[index] == undefined) this.promises[index] = {};

        if (this.promises[index][archiveId] == undefined) {
            let resolveMethod;
            let promise = new Promise((resolve, reject) => {
                resolveMethod = resolve;
            });
            this.promises[index][archiveId] = {
                resolve: resolveMethod,
                promise,
            };
        } else {
            //if its already being loaded
            return this.promises[index][archiveId].promise;
        }

        const unactiveWorker = this.workers.find((x) => !x.active);
        if (unactiveWorker == undefined) {
            this.workQueue.push({
                index,
                segment,
                archiveId,
                compressedData,
                key,
            });
            return;
        }

        unactiveWorker.active = true;
        unactiveWorker.worker.postMessage({ index, segment, archiveId, compressedData, key }, [compressedData]);

        return this.promises[index][archiveId].promise;
    }

    finish() {
        this.workers.forEach((workerObject) => workerObject.worker.terminate());
    }
}