parcel-bundler/lib/Trace.js

Blazing fast, zero configuration web application bundler

'use strict';

// some weird library written by sam
const ChromeTrace = require('chrome-trace-event').Tracer;

class Trace {
  constructor() {
    this.chromeTrace = new ChromeTrace({
      // noStream: true,
    });

    this.tid = 0;
    this.eventId = 0;

    this.init();
  }

  getEventId() {
    const id = this.eventId;
    this.eventId++;
    return id;
  }

  init() {
    this.chromeTrace.instantEvent({
      name: 'TracingStartedInPage',
      id: this.getEventId(),
      cat: ['disabled-by-default-devtools.timeline'],
      args: {
        data: {
          sessionId: '-1',
          page: '0xfff',
          frames: [{
            frame: '0xfff',
            url: 'parcel',
            name: ''
          }]
        }
      }
    });

    this.chromeTrace.instantEvent({
      name: 'TracingStartedInBrowser',
      id: this.getEventId(),
      cat: ['disabled-by-default-devtools.timeline'],
      args: {
        data: {
          sessionId: '-1'
        }
      }
    });
  }

  addCPUProfile(name, profile) {
    const trace = this.chromeTrace;
    const tid = this.tid;
    this.tid++;

    const cpuStartTime = profile.startTime;
    const cpuEndTime = profile.endTime;

    const common = {
      pid: 8763,
      tid
    };

    trace.instantEvent(Object.assign({}, common, {
      id: this.getEventId(),
      ph: 'X',
      cat: ['toplevel'],
      name: 'TaskQueueManager::ProcessTaskFromWorkQueue',
      args: {
        src_file: '../../third_party/WebKit/Source/core/workers/DedicatedWorkerObjectProxy.cpp',
        src_func: 'PostMessageToWorkerObject'
      },
      ts: cpuStartTime,
      dur: cpuEndTime - cpuStartTime
    }));

    trace.completeEvent(Object.assign({}, common, {
      name: 'EvaluateScript',
      id: this.getEventId(),
      cat: ['devtools.timeline'],
      ts: cpuStartTime,
      dur: cpuEndTime - cpuStartTime,
      args: {
        data: {
          url: 'parcel',
          lineNumber: 1,
          columnNumber: 1,
          frame: '0xFFF'
        }
      }
    }));

    trace.instantEvent(Object.assign({}, common, {
      ts: 0,
      ph: 'M',
      cat: ['__metadata'],
      name: 'thread_name',
      args: { name }
    }));

    trace.instantEvent(Object.assign({}, common, {
      name: 'CpuProfile',
      id: this.getEventId(),
      cat: ['disabled-by-default-devtools.timeline'],
      ts: cpuEndTime,
      args: {
        data: {
          cpuProfile: profile
        }
      }
    }));
  }

  build() {
    return this.chromeTrace.events;
  }
}

module.exports = Trace;