mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-01 14:45:29 +00:00
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
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
this.EXPORTED_SYMBOLS = ["DeferredTask"];
|
|
|
|
const Cu = Components.utils;
|
|
const Cc = Components.classes;
|
|
const Ci = Components.interfaces;
|
|
|
|
/**
|
|
* A task that will run after a delay. Multiple attempts to run the same task
|
|
* before the delay will be coalesced
|
|
*
|
|
* Use this for instance if you write data to a file and you expect that you
|
|
* may have to rewrite data very soon afterwards. With |DeferredTask|, the
|
|
* task is delayed by a few milliseconds and, should a new change to the data
|
|
* occur during this period,
|
|
* 1/ only the final version of the data is actually written;
|
|
* 2/ a further grace delay is added to take into account other changes.
|
|
*
|
|
* Constructor
|
|
* @param aDelay The delay time in milliseconds.
|
|
* @param aCallback The code to execute after the delay.
|
|
*/
|
|
this.DeferredTask = function DeferredTask(aCallback, aDelay) {
|
|
this._callback = function onCallback() {
|
|
this._timer = null;
|
|
try {
|
|
aCallback();
|
|
} catch(e) {
|
|
Cu.reportError(e);
|
|
}
|
|
}.bind(this);
|
|
this._delay = aDelay;
|
|
}
|
|
|
|
DeferredTask.prototype = {
|
|
/* Callback */
|
|
_callback: null,
|
|
/* Delay */
|
|
_delay: null,
|
|
/* Timer */
|
|
_timer: null,
|
|
|
|
/**
|
|
* Check the current task state.
|
|
* @returns true if pending, false otherwise.
|
|
*/
|
|
get isPending() {
|
|
return (this._timer != null);
|
|
},
|
|
|
|
/**
|
|
* Start (or postpone) task.
|
|
*/
|
|
start: function DeferredTask_start() {
|
|
if (this._timer) {
|
|
this._timer.cancel();
|
|
}
|
|
this._timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
|
|
this._timer.initWithCallback(
|
|
this._callback, this._delay, Ci.nsITimer.TYPE_ONE_SHOT);
|
|
},
|
|
|
|
/**
|
|
* Perform any postponed task immediately.
|
|
*/
|
|
flush: function DeferredTask_flush() {
|
|
if (this._timer) {
|
|
this.cancel();
|
|
this._callback();
|
|
}
|
|
},
|
|
|
|
/**
|
|
* Cancel any pending task.
|
|
*/
|
|
cancel: function DeferredTask_cancel() {
|
|
if (this._timer) {
|
|
this._timer.cancel();
|
|
this._timer = null;
|
|
}
|
|
}
|
|
};
|