3d-tiles-renderer
Version:
https://github.com/AnalyticalGraphicsInc/3d-tiles/tree/master/specification
170 lines (101 loc) • 2.43 kB
JavaScript
class PriorityQueue {
// returns whether tasks are queued or actively running
get running() {
return this.items.length !== 0 || this.currJobs !== 0;
}
constructor() {
// options
this.maxJobs = 6;
this.items = [];
this.callbacks = new Map();
this.currJobs = 0;
this.scheduled = false;
this.autoUpdate = true;
this.priorityCallback = () => {
throw new Error( 'PriorityQueue: PriorityCallback function not defined.' );
};
// Customizable scheduling callback. Default using requestAnimationFrame()
this.schedulingCallback = func => {
requestAnimationFrame( func );
};
this._runjobs = () => {
this.scheduled = false;
this.tryRunJobs();
};
}
sort() {
const priorityCallback = this.priorityCallback;
const items = this.items;
items.sort( priorityCallback );
}
has( item ) {
return this.callbacks.has( item );
}
add( item, callback ) {
return new Promise( ( resolve, reject ) => {
const items = this.items;
const callbacks = this.callbacks;
items.push( item );
callbacks.set( item, {
callback,
resolve,
reject,
} );
if ( this.autoUpdate ) {
this.scheduleJobRun();
}
} );
}
remove( item ) {
const items = this.items;
const callbacks = this.callbacks;
const index = items.indexOf( item );
if ( index !== - 1 ) {
items.splice( index, 1 );
callbacks.delete( item );
}
}
tryRunJobs() {
this.sort();
const items = this.items;
const callbacks = this.callbacks;
const maxJobs = this.maxJobs;
let iterated = 0;
const completedCallback = () => {
this.currJobs --;
if ( this.autoUpdate ) {
this.scheduleJobRun();
}
};
while ( maxJobs > this.currJobs && items.length > 0 && iterated < maxJobs ) {
this.currJobs ++;
iterated ++;
const item = items.pop();
const { callback, resolve, reject } = callbacks.get( item );
callbacks.delete( item );
let result;
try {
result = callback( item );
} catch ( err ) {
reject( err );
completedCallback();
}
if ( result instanceof Promise ) {
result
.then( resolve )
.catch( reject )
.finally( completedCallback );
} else {
resolve( result );
completedCallback();
}
}
}
scheduleJobRun() {
if ( ! this.scheduled ) {
this.schedulingCallback( this._runjobs );
this.scheduled = true;
}
}
}
export { PriorityQueue };