hotfunction.mozcmd

[{
  name: "hotfunction",
  description: "Records function calls and figures out which functions are 'hot'.",
  params: [{
    name: "action",
    description: "Action to take - start recording, or stop",
    type: {
      name: "selection",
      data: ["start", "stop"]
    }
  }],
  dbg: null,
  frames: {},
  exec: function(args, context) {
    let chromeWin = context.environment.chromeDocument.defaultView;
    let contentWin = context.environment.contentDocument.defaultView;

    if (Debugger == "undefined") {
      let JSDebug = {};
      Components.utils.import("resource://gre/modules/jsdebugger.jsm", JSDebug);
      JSDebug.addDebuggerToGlobal(Components.utils.getGlobalForObject(this));
    }

    if (args.action == "start") {
      if (this.dbg)
        return "Error: Already recording.";

      this.dbg = new Debugger(contentWin);
      this.dbg.onEnterFrame = this.onEnterFrame.bind(this);

      return "Started recording. Run 'hotfunction stop' to stop recording and see results."
    } else {
      if (!this.dbg)
        return "Error: Not currently recording.";

      this.dbg.onEnterFrame = undefined;
      this.dbg = null;

      let ids = Object.keys(this.frames);
      if (ids.length == 0)
        return "Error: No function calls recorded.";

      let orderedFrames = [];
      for (let id of ids)
        orderedFrames.push(this.frames[id]);
      orderedFrames.sort(function(a,b) b.count - a.count);

      let output = "<h1>Top hot functions:</h1><br/>";
      let maxFrames = 10;
      if (maxFrames > orderedFrames.length)
        maxFrames = orderedFrames.length;

      for (let i = 0; i < maxFrames; i++) {
        let frame = orderedFrames[i];
        output += frame.functionName + "  (" + frame.count + " calls) " +
                  frame.scriptURL + ":" + frame.line + "<br/>";
      }
      return output;
    }
  },
  onEnterFrame: function(aFrame) {
    try {
      if (!aFrame.script) {
        if (!("__unknown__" in this.frames))
          this.frames.__unknown__ = 0;
        this.frames.__unknown__++;
        return;
      }
  
      let functionName = "[anonymous]";
      if (aFrame.callee && aFrame.callee.name)
        functionName = aFrame.callee.name;
      let id = aFrame.script.url + ":" +
                 aFrame.script.getOffsetLine(aFrame.offset) + ":" +
                 functionName;
      if (!(id in this.frames)) {
        let frameInfo = {
          scriptURL: aFrame.script.url,
          line: aFrame.script.getOffsetLine(aFrame.offset),
          functionName: functionName,
          count: 0
        };
        this.frames[id] = frameInfo;
      }
      this.frames[id].count++;
    } catch(e) {
      Components.utils.reportError(e);
    }
  }
}]