The Tor Browser: toolkit/components/telemetry/TelemetryStopwatch.jsm@925c144e1f1f

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

     3  * You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 const Cc = Components.classes;

     6 const Ci = Components.interfaces;

     7 const Cu = Components.utils;

     9 this.EXPORTED_SYMBOLS = ["TelemetryStopwatch"];

    11 let Telemetry = Cc["@mozilla.org/base/telemetry;1"]

    12                   .getService(Ci.nsITelemetry);

    14 // simpleTimers are directly associated with a histogram

    15 // name. objectTimers are associated with an object _and_

    16 // a histogram name.

    17 let simpleTimers = {};

    18 let objectTimers = new WeakMap();

    20 this.TelemetryStopwatch = {

    21   /**

    22    * Starts a timer associated with a telemetry histogram. The timer can be

    23    * directly associated with a histogram, or with a pair of a histogram and

    24    * an object.

    25    *

    26    * @param aHistogram a string which must be a valid histogram name

    27    *                   from TelemetryHistograms.h

    28    *

    29    * @param aObj Optional parameter. If specified, the timer is associated

    30    *             with this object, meaning that multiple timers for a same

    31    *             histogram may be run concurrently, as long as they are

    32    *             associated with different objects.

    33    *

    34    * @return true if the timer was successfully started, false otherwise. If a

    35    *         timer already exists, it can't be started again, and the existing

    36    *         one will be cleared in order to avoid measurements errors.

    37    */

    38   start: function(aHistogram, aObj) {

    39     if (!validTypes(aHistogram, aObj))

    40       return false;

    42     let timers;

    43     if (aObj) {

    44       timers = objectTimers.get(aObj, {});

    45       objectTimers.set(aObj, timers);

    46     } else {

    47       timers = simpleTimers;

    48     }

    50     if (timers.hasOwnProperty(aHistogram)) {

    51       delete timers[aHistogram];

    52       Cu.reportError("TelemetryStopwatch: key \"" +

    53                      aHistogram + "\" was already initialized");

    54       return false;

    55     }

    57     timers[aHistogram] = Date.now();

    58     return true;

    59   },

    61   /**

    62    * Deletes the timer associated with a telemetry histogram. The timer can be

    63    * directly associated with a histogram, or with a pair of a histogram and

    64    * an object. Important: Only use this method when a legitimate cancellation

    65    * should be done.

    66    *

    67    * @param aHistogram a string which must be a valid histogram name

    68    *                   from TelemetryHistograms.json

    69    *

    70    * @param aObj Optional parameter. If specified, the timer is associated

    71    *             with this object, meaning that multiple timers for a same

    72    *             histogram may be run concurrently, as long as they are

    73    *             associated with different objects.

    74    *

    75    * @return true if the timer exist and it was cleared, false otherwise.

    76    */

    77   cancel: function ts_cancel(aHistogram, aObj) {

    78     if (!validTypes(aHistogram, aObj))

    79       return false;

    81     let timers = aObj

    82                  ? objectTimers.get(aObj, {})

    83                  : simpleTimers;

    85     if (timers.hasOwnProperty(aHistogram)) {

    86       delete timers[aHistogram];

    87       return true;

    88     }

    90     return false;

    91   },

    93   /**

    94    * Stops the timer associated with the given histogram (and object),

    95    * calculates the time delta between start and finish, and adds the value

    96    * to the histogram.

    97    *

    98    * @param aHistogram a string which must be a valid histogram name

    99    *                   from TelemetryHistograms.h. If an invalid name

   100    *                   is given, the function will throw.

   101    *

   102    * @param aObj Optional parameter which associates the histogram timer with

   103    *             the given object.

   104    *

   105    * @return true if the timer was succesfully stopped and the data was

   106    *         added to the histogram, false otherwise.

   107    */

   108   finish: function(aHistogram, aObj) {

   109     if (!validTypes(aHistogram, aObj))

   110       return false;

   112     let timers = aObj

   113                  ? objectTimers.get(aObj, {})

   114                  : simpleTimers;

   116     let start = timers[aHistogram];

   117     delete timers[aHistogram];

   119     if (start) {

   120       let delta = Date.now() - start;

   121       let histogram = Telemetry.getHistogramById(aHistogram);

   122       histogram.add(delta);

   123       return true;

   124     }

   126     return false;

   127   }

   128 }

   130 function validTypes(aKey, aObj) {

   131   return (typeof aKey == "string") &&

   132          (aObj === undefined || typeof aObj == "object");

   133 }

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