resources/src/startup/profiler.js

   1 /*!
   2  * Augment mw.loader to facilitate module-level profiling.
   3  *
   4  * @author Timo Tijhof
   5  * @since 1.32
   6  */
   7 /* global mw */
   8 ( function () {
   9         'use strict';
  10
  11         var moduleTimes = Object.create( null );
  12
  13         /**
  14          * Private hooks inserted into mw.loader code if MediaWiki configuration
  15          * `$wgResourceLoaderEnableJSProfiler` is `true`.
  16          *
  17          * To use this data, run `mw.inspect( 'time' )` from the browser console.
  18          * See mw#inspect().
  19          *
  20          * @private
  21          * @class
  22          * @singleton
  23          */
  24         mw.loader.profiler = {
  25                 onExecuteStart: function ( moduleName ) {
  26                         var time = performance.now();
  27                         if ( moduleTimes[ moduleName ] ) {
  28                                 throw new Error( 'Unexpected perf record for "' + moduleName + '".' );
  29                         }
  30                         moduleTimes[ moduleName ] = {
  31                                 executeStart: time,
  32                                 executeEnd: null,
  33                                 scriptStart: null,
  34                                 scriptEnd: null
  35                         };
  36                 },
  37                 onExecuteEnd: function ( moduleName ) {
  38                         var time = performance.now();
  39                         moduleTimes[ moduleName ].executeEnd = time;
  40                 },
  41                 onScriptStart: function ( moduleName ) {
  42                         var time = performance.now();
  43                         moduleTimes[ moduleName ].scriptStart = time;
  44                 },
  45                 onScriptEnd: function ( moduleName ) {
  46                         var time = performance.now();
  47                         moduleTimes[ moduleName ].scriptEnd = time;
  48                 },
  49
  50                 /**
  51                  * For internal use by inspect.reports#time.
  52                  *
  53                  * @private
  54                  * @param {string} moduleName
  55                  * @return {Object|null}
  56                  * @throws {Error} If the perf record is incomplete.
  57                  */
  58                 getProfile: function ( moduleName ) {
  59                         var times, key, execute, script, total;
  60                         times = moduleTimes[ moduleName ];
  61                         if ( !times ) {
  62                                 return null;
  63                         }
  64                         for ( key in times ) {
  65                                 if ( times[ key ] === null ) {
  66                                         throw new Error( 'Incomplete perf record for "' + moduleName + '".', times );
  67                                 }
  68                         }
  69                         execute = times.executeEnd - times.executeStart;
  70                         script = times.scriptEnd - times.scriptStart;
  71                         total = execute + script;
  72                         return {
  73                                 name: moduleName,
  74                                 execute: execute,
  75                                 script: script,
  76                                 total: total
  77                         };
  78                 }
  79         };
  80
  81 }() );