gecko-dev/browser/modules/TelemetryTimestamps.jsm
Gavin Sharp f1e0ed635f Bug 723181: add some comments to TelemetryTimestamps, r=mak
--HG--
extra : transplant_source : z%AF9MyF%E6y%16%DAq%170%B7%5D6%DFgE%01
2012-02-01 09:41:55 -08:00

53 lines
1.8 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/. */
let EXPORTED_SYMBOLS = ["TelemetryTimestamps"];
/**
* This module's purpose is to collect timestamps for important
* application-specific events.
*
* The TelemetryPing component attaches the timestamps stored by this module to
* the telemetry submission, substracting the process lifetime so that the times
* are relative to process startup. The overall goal is to produce a basic
* timeline of the startup process.
*/
let timeStamps = {};
let TelemetryTimestamps = {
/**
* Adds a timestamp to the list. The addition of TimeStamps that already have
* a value stored is ignored.
*
* @param name must be a unique, generally "camelCase" descriptor of what the
* timestamp represents. e.g.: "delayedStartupStarted"
* @param value is a timeStamp in milliseconds since the epoch. If omitted,
* defaults to Date.now().
*/
add: function TT_add(name, value) {
// Default to "now" if not specified
if (value == null)
value = Date.now();
if (isNaN(value))
throw new Error("Value must be a timestamp");
// If there's an existing value, just ignore the new value.
if (timeStamps.hasOwnProperty(name))
return;
timeStamps[name] = value;
},
/**
* Returns a JS object containing all of the timeStamps as properties (can be
* easily serialized to JSON). Used by TelemetryPing to retrieve the data
* to attach to the telemetry submission.
*/
get: function TT_get() {
// Return a copy of the object by passing it through JSON.
return JSON.parse(JSON.stringify(timeStamps));
}
};