78 lines
2.7 KiB
JavaScript
78 lines
2.7 KiB
JavaScript
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/*
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* This is basically a Javascript Proxy for 'new Worker()'
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* which allows calling worker-functions via promises.
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*
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* It's basically comlink without the fat.
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*
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* const w = new PromiseWorker("worker.js", (cb,event_or_fn,data) => {
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* cb(event_or_fn,data) // decorate/ratelimit/hooks here
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* })
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* w.foo().then( console.dir )
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*
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* in worker.js define a function: this.foo = () => return {foo:"Bar"}
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*/
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function PromiseWorker(file, onmessage){
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let proxy
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const worker = new Worker(file)
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worker.onmessage = (e) => { // handle messages originating from worker
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const {event,data} = e.data // this is worker.onmessage(...)
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const cb = (event,data) => () => { //
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if( data.promiseId ){ //
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proxy.resolver(data) // forward to promise resolver
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}
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}
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onmessage(cb,event,data)
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}
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return proxy = new Proxy(this,{
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get(me,k){
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if( k.match(/(postMessage|onmessage)/) ) return worker[k].bind(worker)
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if( k.match(/(resolver|promise)/) ) return this[k].bind(this)
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// promisify postMessage(...) call
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return function(){
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return this.promise(me,{event: k, data: [...arguments] })
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}
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},
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promise(me,msg){
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if( typeof msg != 'object' || !msg.event || !msg.data ){
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throw 'worker.promise({event:..,data:..}) did not receive correct msg : '+JSON.stringify(msg)
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}
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this.resolvers = this.resolvers || {last:1,pending:{}}
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msg.data.promiseId = this.resolvers.last++
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// Send id and task to WebWorker
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worker.postMessage(msg, PromiseWorker.prototype.getTransferable(msg.data) )
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return new Promise( resolve => this.resolvers.pending[ msg.data.promiseId ] = resolve );
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},
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resolver(data){
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if( !data || !data.promiseId ) throw 'promiseId not given'
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this.resolvers.pending[ data.promiseId ](data.result);
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delete this.resolvers.pending[ data.promiseId ]; // Prevent memory leak
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}
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})
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}
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PromiseWorker.prototype.getTransferable = function(data){
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let objs = []
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function isTransferable(obj) {
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return obj instanceof ArrayBuffer ||
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obj instanceof MessagePort ||
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obj instanceof ImageBitmap ||
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(typeof OffscreenCanvas !== 'undefined' && obj instanceof OffscreenCanvas) ||
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(typeof ReadableStream !== 'undefined' && obj instanceof ReadableStream) ||
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(typeof WritableStream !== 'undefined' && obj instanceof WritableStream) ||
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(typeof TransformStream !== 'undefined' && obj instanceof TransformStream);
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}
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for( var i in data ){
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if( isTransferable(data[i]) ) objs.push(data[i])
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}
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if( objs.length ) debugger
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return objs.length ? objs : undefined
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}
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