168 lines
3.0 KiB
JavaScript
168 lines
3.0 KiB
JavaScript
/**
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* A simple pool for managing Web Workers.
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*
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* @three_import import { WorkerPool } from 'three/addons/utils/WorkerPool.js';
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*/
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export class WorkerPool {
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/**
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* Constructs a new Worker pool.
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*
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* @param {number} [pool=4] - The size of the pool.
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*/
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constructor( pool = 4 ) {
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/**
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* The size of the pool.
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*
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* @type {number}
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* @default 4
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*/
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this.pool = pool;
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/**
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* A message queue.
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*
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* @type {Array<Object>}
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*/
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this.queue = [];
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/**
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* An array of Workers.
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*
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* @type {Array<Worker>}
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*/
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this.workers = [];
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/**
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* An array with resolve functions for messages.
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*
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* @type {Array<Function>}
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*/
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this.workersResolve = [];
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/**
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* The current worker status.
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*
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* @type {number}
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*/
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this.workerStatus = 0;
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/**
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* A factory function for creating workers.
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*
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* @type {?Function}
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*/
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this.workerCreator = null;
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}
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_initWorker( workerId ) {
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if ( ! this.workers[ workerId ] ) {
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const worker = this.workerCreator();
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worker.addEventListener( 'message', this._onMessage.bind( this, workerId ) );
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this.workers[ workerId ] = worker;
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}
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}
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_getIdleWorker() {
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for ( let i = 0; i < this.pool; i ++ )
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if ( ! ( this.workerStatus & ( 1 << i ) ) ) return i;
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return - 1;
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}
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_onMessage( workerId, msg ) {
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const resolve = this.workersResolve[ workerId ];
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resolve && resolve( msg );
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if ( this.queue.length ) {
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const { resolve, msg, transfer } = this.queue.shift();
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this.workersResolve[ workerId ] = resolve;
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this.workers[ workerId ].postMessage( msg, transfer );
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} else {
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this.workerStatus ^= 1 << workerId;
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}
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}
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/**
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* Sets a function that is responsible for creating Workers.
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*
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* @param {Function} workerCreator - The worker creator function.
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*/
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setWorkerCreator( workerCreator ) {
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this.workerCreator = workerCreator;
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}
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/**
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* Sets the Worker limit
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*
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* @param {number} pool - The size of the pool.
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*/
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setWorkerLimit( pool ) {
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this.pool = pool;
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}
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/**
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* Post a message to an idle Worker. If no Worker is available,
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* the message is pushed into a message queue for later processing.
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*
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* @param {Object} msg - The message.
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* @param {Array<ArrayBuffer>} transfer - An array with array buffers for data transfer.
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* @return {Promise} A Promise that resolves when the message has been processed.
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*/
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postMessage( msg, transfer ) {
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return new Promise( ( resolve ) => {
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const workerId = this._getIdleWorker();
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if ( workerId !== - 1 ) {
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this._initWorker( workerId );
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this.workerStatus |= 1 << workerId;
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this.workersResolve[ workerId ] = resolve;
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this.workers[ workerId ].postMessage( msg, transfer );
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} else {
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this.queue.push( { resolve, msg, transfer } );
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}
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} );
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}
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/**
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* Terminates all Workers of this pool. Call this method whenever this
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* Worker pool is no longer used in your app.
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*/
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dispose() {
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this.workers.forEach( ( worker ) => worker.terminate() );
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this.workersResolve.length = 0;
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this.workers.length = 0;
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this.queue.length = 0;
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this.workerStatus = 0;
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}
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}
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