next
Version:
The React Framework
17 lines • 2.78 kB
JavaScript
;exports.__esModule=true;exports.createTrace=void 0;var _fs=_interopRequireDefault(require("fs"));var _path=_interopRequireDefault(require("path"));function _interopRequireDefault(obj){return obj&&obj.__esModule?obj:{default:obj};}let maybeInspector;try{maybeInspector=require('inspector');}catch(e){console.log('Unable to CPU profile in < node 8.0');}class Profiler{constructor(inspector){this.session=undefined;this.inspector=inspector;}hasSession(){return this.session!==undefined;}startProfiling(){if(this.inspector===undefined){return Promise.resolve();}try{this.session=new maybeInspector.Session();this.session.connect();}catch(_){this.session=undefined;return Promise.resolve();}return Promise.all([this.sendCommand('Profiler.setSamplingInterval',{interval:100}),this.sendCommand('Profiler.enable'),this.sendCommand('Profiler.start')]);}sendCommand(method,params){if(this.hasSession()){return new Promise((resolve,reject)=>{return this.session.post(method,params,(err,sessionParams)=>{if(err!==null){reject(err);}else{resolve(sessionParams);}});});}else{return Promise.resolve();}}destroy(){if(this.hasSession()){this.session.disconnect();}return Promise.resolve();}stopProfiling(){return this.sendCommand('Profiler.stop');}}// eslint-disable-next-line import/no-extraneous-dependencies
const{Tracer}=require('chrome-trace-event');/**
* an object that wraps Tracer and Profiler with a counter
* @typedef {Object} Trace
* @property {Tracer} trace instance of Tracer
* @property {number} counter Counter
* @property {Profiler} profiler instance of Profiler
* @property {Function} end the end function
*/ /**
* @param {string} outputPath The location where to write the log.
* @returns {Trace} The trace object
*/const createTrace=outputPath=>{const trace=new Tracer({noStream:true});const profiler=new Profiler(maybeInspector);if(/\/|\\/.test(outputPath)){const dirPath=_path.default.dirname(outputPath);_fs.default.mkdirSync(dirPath,{recursive:true});}const fsStream=_fs.default.createWriteStream(outputPath);let counter=0;trace.pipe(fsStream);// These are critical events that need to be inserted so that tools like
// chrome dev tools can load the profile.
trace.instantEvent({name:'TracingStartedInPage',id:++counter,cat:['disabled-by-default-devtools.timeline'],args:{data:{sessionId:'-1',page:'0xfff',frames:[{frame:'0xfff',url:'webpack',name:''}]}}});trace.instantEvent({name:'TracingStartedInBrowser',id:++counter,cat:['disabled-by-default-devtools.timeline'],args:{data:{sessionId:'-1'}}});return{trace,counter,profiler,end:callback=>{// Wait until the write stream finishes.
fsStream.on('finish',()=>{callback();});// Tear down the readable trace stream.
trace.push(null);}};};exports.createTrace=createTrace;
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