resources/src/startup/profiler.js

   1 /*!
   2  * Augment mw.loader to facilitate module-level profiling.
   3  *
   4  * @since 1.32
   5  */
   6 /* global mw */
   7 ( function () {
   8         'use strict';
   9
  10         var moduleTimes = Object.create( null );
  11
  12         /**
  13          * Private hooks inserted into mw.loader code if MediaWiki configuration
  14          * `$wgResourceLoaderEnableJSProfiler` is `true`.
  15          *
  16          * To use this data, run `mw.inspect( 'time' )` from the browser console.
  17          * See mw#inspect().
  18          *
  19          * @private
  20          * @class
  21          * @singleton
  22          */
  23         mw.loader.profiler = {
  24                 onExecuteStart: function ( moduleName ) {
  25                         var time = performance.now();
  26                         if ( moduleTimes[ moduleName ] ) {
  27                                 throw new Error( 'Unexpected perf record for "' + moduleName + '".' );
  28                         }
  29                         moduleTimes[ moduleName ] = {
  30                                 executeStart: time,
  31                                 executeEnd: null,
  32                                 scriptStart: null,
  33                                 scriptEnd: null
  34                         };
  35                 },
  36                 onExecuteEnd: function ( moduleName ) {
  37                         var time = performance.now();
  38                         moduleTimes[ moduleName ].executeEnd = time;
  39                 },
  40                 onScriptStart: function ( moduleName ) {
  41                         var time = performance.now();
  42                         moduleTimes[ moduleName ].scriptStart = time;
  43                 },
  44                 onScriptEnd: function ( moduleName ) {
  45                         var time = performance.now();
  46                         moduleTimes[ moduleName ].scriptEnd = time;
  47                 },
  48
  49                 /**
  50                  * For internal use by inspect.reports#time.
  51                  *
  52                  * @private
  53                  * @param {string} moduleName
  54                  * @return {Object|null}
  55                  * @throws {Error} If the perf record is incomplete.
  56                  */
  57                 getProfile: function ( moduleName ) {
  58                         var times, key, execute, script, total;
  59                         times = moduleTimes[ moduleName ];
  60                         if ( !times ) {
  61                                 return null;
  62                         }
  63                         for ( key in times ) {
  64                                 if ( times[ key ] === null ) {
  65                                         throw new Error( 'Incomplete perf record for "' + moduleName + '".', times );
  66                                 }
  67                         }
  68                         execute = times.executeEnd - times.executeStart;
  69                         script = times.scriptEnd - times.scriptStart;
  70                         total = execute + script;
  71                         return {
  72                                 name: moduleName,
  73                                 execute: execute,
  74                                 script: script,
  75                                 total: total
  76                         };
  77                 }
  78         };
  79
  80 }() );