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86 lines
2.1 KiB
JavaScript
86 lines
2.1 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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this.EXPORTED_SYMBOLS = ["DeferredTask"];
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const Cu = Components.utils;
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const Cc = Components.classes;
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const Ci = Components.interfaces;
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/**
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* A task that will run after a delay. Multiple attempts to run the same task
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* before the delay will be coalesced
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*
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* Use this for instance if you write data to a file and you expect that you
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* may have to rewrite data very soon afterwards. With |DeferredTask|, the
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* task is delayed by a few milliseconds and, should a new change to the data
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* occur during this period,
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* 1/ only the final version of the data is actually written;
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* 2/ a further grace delay is added to take into account other changes.
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*
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* Constructor
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* @param aDelay The delay time in milliseconds.
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* @param aCallback The code to execute after the delay.
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*/
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this.DeferredTask = function DeferredTask(aCallback, aDelay) {
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this._callback = function onCallback() {
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this._timer = null;
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try {
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aCallback();
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} catch(e) {
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Cu.reportError(e);
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}
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}.bind(this);
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this._delay = aDelay;
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}
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DeferredTask.prototype = {
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/* Callback */
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_callback: null,
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/* Delay */
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_delay: null,
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/* Timer */
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_timer: null,
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/**
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* Check the current task state.
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* @returns true if pending, false otherwise.
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*/
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get isPending() {
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return (this._timer != null);
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},
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/**
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* Start (or postpone) task.
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*/
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start: function DeferredTask_start() {
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if (this._timer) {
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this._timer.cancel();
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}
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this._timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
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this._timer.initWithCallback(
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this._callback, this._delay, Ci.nsITimer.TYPE_ONE_SHOT);
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},
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/**
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* Perform any postponed task immediately.
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*/
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flush: function DeferredTask_flush() {
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if (this._timer) {
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this.cancel();
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this._callback();
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}
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},
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/**
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* Cancel any pending task.
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*/
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cancel: function DeferredTask_cancel() {
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if (this._timer) {
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this._timer.cancel();
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this._timer = null;
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}
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}
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};
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