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/* 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/. */
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cu = Components.utils;
this.EXPORTED_SYMBOLS = ["TelemetryStopwatch"];
let Telemetry = Cc["@mozilla.org/base/telemetry;1"]
.getService(Ci.nsITelemetry);
// simpleTimers are directly associated with a histogram
// name. objectTimers are associated with an object _and_
// a histogram name.
let simpleTimers = {};
let objectTimers = new WeakMap();
this.TelemetryStopwatch = {
/**
* Starts a timer associated with a telemetry histogram. The timer can be
* directly associated with a histogram, or with a pair of a histogram and
* an object.
*
* @param aHistogram a string which must be a valid histogram name
* from TelemetryHistograms.h
*
* @param aObj Optional parameter. If specified, the timer is associated
* with this object, meaning that multiple timers for a same
* histogram may be run concurrently, as long as they are
* associated with different objects.
*
* @return true if the timer was successfully started, false otherwise. If a
* timer already exists, it can't be started again, and the existing
* one will be cleared in order to avoid measurements errors.
*/
start: function(aHistogram, aObj) {
if (!validTypes(aHistogram, aObj))
return false;
let timers;
if (aObj) {
timers = objectTimers.get(aObj, {});
objectTimers.set(aObj, timers);
} else {
timers = simpleTimers;
}
if (timers.hasOwnProperty(aHistogram)) {
delete timers[aHistogram];
Cu.reportError("TelemetryStopwatch: key \"" +
aHistogram + "\" was already initialized");
return false;
}
timers[aHistogram] = Date.now();
return true;
},
/**
* Deletes the timer associated with a telemetry histogram. The timer can be
* directly associated with a histogram, or with a pair of a histogram and
* an object. Important: Only use this method when a legitimate cancellation
* should be done.
*
* @param aHistogram a string which must be a valid histogram name
* from TelemetryHistograms.json
*
* @param aObj Optional parameter. If specified, the timer is associated
* with this object, meaning that multiple timers for a same
* histogram may be run concurrently, as long as they are
* associated with different objects.
*
* @return true if the timer exist and it was cleared, false otherwise.
*/
cancel: function ts_cancel(aHistogram, aObj) {
if (!validTypes(aHistogram, aObj))
return false;
let timers = aObj
? objectTimers.get(aObj, {})
: simpleTimers;
if (timers.hasOwnProperty(aHistogram)) {
delete timers[aHistogram];
return true;
}
return false;
},
/**
* Stops the timer associated with the given histogram (and object),
* calculates the time delta between start and finish, and adds the value
* to the histogram.
*
* @param aHistogram a string which must be a valid histogram name
* from TelemetryHistograms.h. If an invalid name
* is given, the function will throw.
*
* @param aObj Optional parameter which associates the histogram timer with
* the given object.
*
* @return true if the timer was succesfully stopped and the data was
* added to the histogram, false otherwise.
*/
finish: function(aHistogram, aObj) {
if (!validTypes(aHistogram, aObj))
return false;
let timers = aObj
? objectTimers.get(aObj, {})
: simpleTimers;
let start = timers[aHistogram];
delete timers[aHistogram];
if (start) {
let delta = Date.now() - start;
let histogram = Telemetry.getHistogramById(aHistogram);
histogram.add(delta);
return true;
}
return false;
}
}
function validTypes(aKey, aObj) {
return (typeof aKey == "string") &&
(aObj === undefined || typeof aObj == "object");
}
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