117 lines
2.7 KiB
JavaScript
117 lines
2.7 KiB
JavaScript
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"use strict";
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var utils = require("../utils");
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var GenericWorker = require("./GenericWorker");
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// the size of the generated chunks
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// TODO expose this as a public variable
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var DEFAULT_BLOCK_SIZE = 16 * 1024;
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/**
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* A worker that reads a content and emits chunks.
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* @constructor
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* @param {Promise} dataP the promise of the data to split
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*/
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function DataWorker(dataP) {
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GenericWorker.call(this, "DataWorker");
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var self = this;
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this.dataIsReady = false;
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this.index = 0;
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this.max = 0;
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this.data = null;
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this.type = "";
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this._tickScheduled = false;
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dataP.then(function (data) {
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self.dataIsReady = true;
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self.data = data;
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self.max = data && data.length || 0;
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self.type = utils.getTypeOf(data);
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if(!self.isPaused) {
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self._tickAndRepeat();
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}
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}, function (e) {
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self.error(e);
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});
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}
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utils.inherits(DataWorker, GenericWorker);
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/**
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* @see GenericWorker.cleanUp
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*/
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DataWorker.prototype.cleanUp = function () {
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GenericWorker.prototype.cleanUp.call(this);
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this.data = null;
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};
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/**
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* @see GenericWorker.resume
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*/
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DataWorker.prototype.resume = function () {
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if(!GenericWorker.prototype.resume.call(this)) {
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return false;
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}
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if (!this._tickScheduled && this.dataIsReady) {
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this._tickScheduled = true;
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utils.delay(this._tickAndRepeat, [], this);
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}
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return true;
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};
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/**
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* Trigger a tick a schedule an other call to this function.
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*/
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DataWorker.prototype._tickAndRepeat = function() {
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this._tickScheduled = false;
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if(this.isPaused || this.isFinished) {
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return;
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}
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this._tick();
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if(!this.isFinished) {
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utils.delay(this._tickAndRepeat, [], this);
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this._tickScheduled = true;
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}
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};
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/**
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* Read and push a chunk.
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*/
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DataWorker.prototype._tick = function() {
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if(this.isPaused || this.isFinished) {
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return false;
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}
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var size = DEFAULT_BLOCK_SIZE;
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var data = null, nextIndex = Math.min(this.max, this.index + size);
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if (this.index >= this.max) {
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// EOF
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return this.end();
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} else {
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switch(this.type) {
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case "string":
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data = this.data.substring(this.index, nextIndex);
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break;
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case "uint8array":
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data = this.data.subarray(this.index, nextIndex);
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break;
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case "array":
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case "nodebuffer":
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data = this.data.slice(this.index, nextIndex);
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break;
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}
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this.index = nextIndex;
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return this.push({
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data : data,
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meta : {
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percent : this.max ? this.index / this.max * 100 : 0
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}
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});
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}
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};
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module.exports = DataWorker;
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