The Tor Browser: toolkit/devtools/server/actors/tracer.js@b8a032363ba2 (annotated)

toolkit/devtools/server/actors/tracer.js@b8a032363ba2 (annotated)

toolkit/devtools/server/actors/tracer.js

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 const { Cu } = require("chrome");
 const { DebuggerServer } = require("devtools/server/main");
 const { DevToolsUtils } = Cu.import("resource://gre/modules/devtools/DevToolsUtils.jsm", {});
 Cu.import("resource://gre/modules/jsdebugger.jsm");
 addDebuggerToGlobal(this);
 // TODO bug 943125: remove this polyfill and use Debugger.Frame.prototype.depth
 // once it is implemented.
 if (!Object.getOwnPropertyDescriptor(Debugger.Frame.prototype, "depth")) {
   Debugger.Frame.prototype._depth = null;
   Object.defineProperty(Debugger.Frame.prototype, "depth", {
     get: function () {
       if (this._depth === null) {
         if (!this.older) {
           this._depth = 0;
         } else {
           // Hide depth from self-hosted frames.
           const increment = this.script && this.script.url == "self-hosted"
             ? 0
             : 1;
           this._depth = increment + this.older.depth;
         }
       }
       return this._depth;
     }
   });
 }
 const { setTimeout } = require("sdk/timers");
 /**
  * The number of milliseconds we should buffer frame enter/exit packets before
  * sending.
  */
 const BUFFER_SEND_DELAY = 50;
 /**
  * The maximum number of arguments we will send for any single function call.
  */
 const MAX_ARGUMENTS = 3;
 /**
  * The maximum number of an object's properties we will serialize.
  */
 const MAX_PROPERTIES = 3;
 /**
  * The complete set of trace types supported.
  */
 const TRACE_TYPES = new Set([
   "time",
   "return",
   "throw",
   "yield",
   "name",
   "location",
   "callsite",
   "parameterNames",
   "arguments",
   "depth"
 ]);
 /**
  * Creates a TraceActor. TraceActor provides a stream of function
  * call/return packets to a remote client gathering a full trace.
  */
 function TraceActor(aConn, aParentActor)
 {
   this._attached = false;
   this._activeTraces = new MapStack();
   this._totalTraces = 0;
   this._startTime = 0;
   // Keep track of how many different trace requests have requested what kind of
   // tracing info. This way we can minimize the amount of data we are collecting
   // at any given time.
   this._requestsForTraceType = Object.create(null);
   for (let type of TRACE_TYPES) {
     this._requestsForTraceType[type] = 0;
   }
   this._sequence = 0;
   this._bufferSendTimer = null;
   this._buffer = [];
   this.onExitFrame = this.onExitFrame.bind(this);
   // aParentActor.window might be an Xray for a window, but it might also be a
   // double-wrapper for a Sandbox.  We want to unwrap the latter but not the
   // former.
   this.global = aParentActor.window;
   if (!Cu.isXrayWrapper(this.global)) {
       this.global = this.global.wrappedJSObject;
   }
 }
 TraceActor.prototype = {
   actorPrefix: "trace",
   get attached() { return this._attached; },
   get idle()     { return this._attached && this._activeTraces.size === 0; },
   get tracing()  { return this._attached && this._activeTraces.size > 0; },
   /**
    * Buffer traces and only send them every BUFFER_SEND_DELAY milliseconds.
    */
   _send: function(aPacket) {
     this._buffer.push(aPacket);
     if (this._bufferSendTimer === null) {
       this._bufferSendTimer = setTimeout(() => {
         this.conn.send({
           from: this.actorID,
           type: "traces",
           traces: this._buffer.splice(0, this._buffer.length)
         });
         this._bufferSendTimer = null;
       }, BUFFER_SEND_DELAY);
     }
   },
   /**
    * Initializes a Debugger instance and adds listeners to it.
    */
   _initDebugger: function() {
     this.dbg = new Debugger();
     this.dbg.onEnterFrame = this.onEnterFrame.bind(this);
     this.dbg.onNewGlobalObject = this.globalManager.onNewGlobal.bind(this);
     this.dbg.enabled = false;
   },
   /**
    * Add a debuggee global to the Debugger object.
    */
   _addDebuggee: function(aGlobal) {
     try {
       this.dbg.addDebuggee(aGlobal);
     } catch (e) {
       // Ignore attempts to add the debugger's compartment as a debuggee.
       DevToolsUtils.reportException("TraceActor",
                       new Error("Ignoring request to add the debugger's "
                                 + "compartment as a debuggee"));
     }
   },
   /**
    * Add the provided window and all windows in its frame tree as debuggees.
    */
   _addDebuggees: function(aWindow) {
     this._addDebuggee(aWindow);
     let frames = aWindow.frames;
     if (frames) {
       for (let i = 0; i < frames.length; i++) {
         this._addDebuggees(frames[i]);
       }
     }
   },
   /**
    * An object used by TraceActors to tailor their behavior depending
    * on the debugging context required (chrome or content).
    */
   globalManager: {
     /**
      * Adds all globals in the global object as debuggees.
      */
     findGlobals: function() {
       this._addDebuggees(this.global);
     },
     /**
      * A function that the engine calls when a new global object has been
      * created. Adds the global object as a debuggee if it is in the content
      * window.
      *
      * @param aGlobal Debugger.Object
      *        The new global object that was created.
      */
     onNewGlobal: function(aGlobal) {
       // Content debugging only cares about new globals in the content
       // window, like iframe children.
       if (aGlobal.hostAnnotations &&
           aGlobal.hostAnnotations.type == "document" &&
           aGlobal.hostAnnotations.element === this.global) {
         this._addDebuggee(aGlobal);
       }
     },
   },
   /**
    * Handle a protocol request to attach to the trace actor.
    *
    * @param aRequest object
    *        The protocol request object.
    */
   onAttach: function(aRequest) {
     if (this.attached) {
       return {
         error: "wrongState",
         message: "Already attached to a client"
       };
     }
     if (!this.dbg) {
       this._initDebugger();
       this.globalManager.findGlobals.call(this);
     }
     this._attached = true;
     return {
       type: "attached",
       traceTypes: Object.keys(this._requestsForTraceType)
         .filter(k => !!this._requestsForTraceType[k])
     };
   },
   /**
    * Handle a protocol request to detach from the trace actor.
    *
    * @param aRequest object
    *        The protocol request object.
    */
   onDetach: function() {
     while (this.tracing) {
       this.onStopTrace();
     }
     this.dbg = null;
     this._attached = false;
     return { type: "detached" };
   },
   /**
    * Handle a protocol request to start a new trace.
    *
    * @param aRequest object
    *        The protocol request object.
    */
   onStartTrace: function(aRequest) {
     for (let traceType of aRequest.trace) {
       if (!TRACE_TYPES.has(traceType)) {
         return {
           error: "badParameterType",
           message: "No such trace type: " + traceType
         };
       }
     }
     if (this.idle) {
       this.dbg.enabled = true;
       this._sequence = 0;
       this._startTime = Date.now();
     }
     // Start recording all requested trace types.
     for (let traceType of aRequest.trace) {
       this._requestsForTraceType[traceType]++;
     }
     this._totalTraces++;
     let name = aRequest.name || "Trace " + this._totalTraces;
     this._activeTraces.push(name, aRequest.trace);
     return { type: "startedTrace", why: "requested", name: name };
   },
   /**
    * Handle a protocol request to end a trace.
    *
    * @param aRequest object
    *        The protocol request object.
    */
   onStopTrace: function(aRequest) {
     if (!this.tracing) {
       return {
         error: "wrongState",
         message: "No active traces"
       };
     }
     let stoppedTraceTypes, name;
     if (aRequest && aRequest.name) {
       name = aRequest.name;
       if (!this._activeTraces.has(name)) {
         return {
           error: "noSuchTrace",
           message: "No active trace with name: " + name
         };
       }
       stoppedTraceTypes = this._activeTraces.delete(name);
     } else {
       name = this._activeTraces.peekKey();
       stoppedTraceTypes = this._activeTraces.pop();
     }
     for (let traceType of stoppedTraceTypes) {
       this._requestsForTraceType[traceType]--;
     }
     if (this.idle) {
       this.dbg.enabled = false;
     }
     return { type: "stoppedTrace", why: "requested", name: name };
   },
   // JS Debugger API hooks.
   /**
    * Called by the engine when a frame is entered. Sends an unsolicited packet
    * to the client carrying requested trace information.
    *
    * @param aFrame Debugger.frame
    *        The stack frame that was entered.
    */
   onEnterFrame: function(aFrame) {
     if (aFrame.script && aFrame.script.url == "self-hosted") {
       return;
     }
     let packet = {
       type: "enteredFrame",
       sequence: this._sequence++
     };
     if (this._requestsForTraceType.name) {
       packet.name = aFrame.callee
         ? aFrame.callee.displayName || "(anonymous function)"
         : "(" + aFrame.type + ")";
     }
     if (this._requestsForTraceType.location && aFrame.script) {
       // We should return the location of the start of the script, but
       // Debugger.Script does not provide complete start locations (bug
       // 901138). Instead, return the current offset (the location of the first
       // statement in the function).
       packet.location = {
         url: aFrame.script.url,
         line: aFrame.script.getOffsetLine(aFrame.offset),
         column: getOffsetColumn(aFrame.offset, aFrame.script)
       };
     }
     if (this._requestsForTraceType.callsite
         && aFrame.older
         && aFrame.older.script) {
       let older = aFrame.older;
       packet.callsite = {
         url: older.script.url,
         line: older.script.getOffsetLine(older.offset),
         column: getOffsetColumn(older.offset, older.script)
       };
     }
     if (this._requestsForTraceType.time) {
       packet.time = Date.now() - this._startTime;
     }
     if (this._requestsForTraceType.parameterNames && aFrame.callee) {
       packet.parameterNames = aFrame.callee.parameterNames;
     }
     if (this._requestsForTraceType.arguments && aFrame.arguments) {
       packet.arguments = [];
       let i = 0;
       for (let arg of aFrame.arguments) {
         if (i++ > MAX_ARGUMENTS) {
           break;
         }
         packet.arguments.push(createValueSnapshot(arg, true));
       }
     }
     if (this._requestsForTraceType.depth) {
       packet.depth = aFrame.depth;
     }
     const onExitFrame = this.onExitFrame;
     aFrame.onPop = function (aCompletion) {
       onExitFrame(this, aCompletion);
     };
     this._send(packet);
   },
   /**
    * Called by the engine when a frame is exited. Sends an unsolicited packet to
    * the client carrying requested trace information.
    *
    * @param Debugger.Frame aFrame
    *        The Debugger.Frame that was just exited.
    * @param aCompletion object
    *        The debugger completion value for the frame.
    */
   onExitFrame: function(aFrame, aCompletion) {
     let packet = {
       type: "exitedFrame",
       sequence: this._sequence++,
     };
     if (!aCompletion) {
       packet.why = "terminated";
     } else if (aCompletion.hasOwnProperty("return")) {
       packet.why = "return";
     } else if (aCompletion.hasOwnProperty("yield")) {
       packet.why = "yield";
     } else {
       packet.why = "throw";
     }
     if (this._requestsForTraceType.time) {
       packet.time = Date.now() - this._startTime;
     }
     if (this._requestsForTraceType.depth) {
       packet.depth = aFrame.depth;
     }
     if (aCompletion) {
       if (this._requestsForTraceType.return && "return" in aCompletion) {
         packet.return = createValueSnapshot(aCompletion.return, true);
       }
       else if (this._requestsForTraceType.throw && "throw" in aCompletion) {
         packet.throw = createValueSnapshot(aCompletion.throw, true);
       }
       else if (this._requestsForTraceType.yield && "yield" in aCompletion) {
         packet.yield = createValueSnapshot(aCompletion.yield, true);
       }
     }
     this._send(packet);
   }
 };
 /**
  * The request types this actor can handle.
  */
 TraceActor.prototype.requestTypes = {
   "attach": TraceActor.prototype.onAttach,
   "detach": TraceActor.prototype.onDetach,
   "startTrace": TraceActor.prototype.onStartTrace,
   "stopTrace": TraceActor.prototype.onStopTrace
 };
 exports.register = function(handle) {
   handle.addTabActor(TraceActor, "traceActor");
 };
 exports.unregister = function(handle) {
   handle.removeTabActor(TraceActor, "traceActor");
 };
 /**
  * MapStack is a collection of key/value pairs with stack ordering,
  * where keys are strings and values are any JS value. In addition to
  * the push and pop stack operations, supports a "delete" operation,
  * which removes the value associated with a given key from any
  * location in the stack.
  */
 function MapStack()
 {
   // Essentially a MapStack is just sugar-coating around a standard JS
   // object, plus the _stack array to track ordering.
   this._stack = [];
   this._map = Object.create(null);
 }
 MapStack.prototype = {
   get size() { return this._stack.length; },
   /**
    * Return the key for the value on the top of the stack, or
    * undefined if the stack is empty.
    */
   peekKey: function() {
     return this._stack[this.size - 1];
   },
   /**
    * Return true iff a value has been associated with the given key.
    *
    * @param aKey string
    *        The key whose presence is to be tested.
    */
   has: function(aKey) {
     return Object.prototype.hasOwnProperty.call(this._map, aKey);
   },
   /**
    * Return the value associated with the given key, or undefined if
    * no value is associated with the key.
    *
    * @param aKey string
    *        The key whose associated value is to be returned.
    */
   get: function(aKey) {
     return this._map[aKey];
   },
   /**
    * Push a new value onto the stack. If another value with the same
    * key is already on the stack, it will be removed before the new
    * value is pushed onto the top of the stack.
    *
    * @param aKey string
    *        The key of the object to push onto the stack.
    *
    * @param aValue
    *        The value to push onto the stack.
    */
   push: function(aKey, aValue) {
     this.delete(aKey);
     this._stack.push(aKey);
     this._map[aKey] = aValue;
   },
   /**
    * Remove the value from the top of the stack and return it.
    * Returns undefined if the stack is empty.
    */
   pop: function() {
     let key = this.peekKey();
     let value = this.get(key);
     this._stack.pop();
     delete this._map[key];
     return value;
   },
   /**
    * Remove the value associated with the given key from the stack and
    * return it. Returns undefined if no value is associated with the
    * given key.
    *
    * @param aKey string
    *        The key for the value to remove from the stack.
    */
   delete: function(aKey) {
     let value = this.get(aKey);
     if (this.has(aKey)) {
       let keyIndex = this._stack.lastIndexOf(aKey);
       this._stack.splice(keyIndex, 1);
       delete this._map[aKey];
     }
     return value;
   }
 };
 // TODO bug 863089: use Debugger.Script.prototype.getOffsetColumn when
 // it is implemented.
 function getOffsetColumn(aOffset, aScript) {
   return 0;
 }
 // Serialization helper functions. Largely copied from script.js and modified
 // for use in serialization rather than object actor requests.
 /**
  * Create a grip for the given debuggee value.
  *
  * @param aValue Debugger.Object|primitive
  *        The value to describe with the created grip.
  *
  * @param aDetailed boolean
  *        If true, capture slightly more detailed information, like some
  *        properties on an object.
  *
  * @return Object
  *         A primitive value or a snapshot of an object.
  */
 function createValueSnapshot(aValue, aDetailed=false) {
   switch (typeof aValue) {
     case "boolean":
       return aValue;
     case "string":
       if (aValue.length >= DebuggerServer.LONG_STRING_LENGTH) {
         return {
           type: "longString",
           initial: aValue.substring(0, DebuggerServer.LONG_STRING_INITIAL_LENGTH),
           length: aValue.length
         };
       }
       return aValue;
     case "number":
       if (aValue === Infinity) {
         return { type: "Infinity" };
       } else if (aValue === -Infinity) {
         return { type: "-Infinity" };
       } else if (Number.isNaN(aValue)) {
         return { type: "NaN" };
       } else if (!aValue && 1 / aValue === -Infinity) {
         return { type: "-0" };
       }
       return aValue;
     case "undefined":
       return { type: "undefined" };
     case "object":
       if (aValue === null) {
         return { type: "null" };
       }
       return aDetailed
         ? detailedObjectSnapshot(aValue)
         : objectSnapshot(aValue);
     default:
       DevToolsUtils.reportException("TraceActor",
                       new Error("Failed to provide a grip for: " + aValue));
       return null;
   }
 }
 /**
  * Create a very minimal snapshot of the given debuggee object.
  *
  * @param aObject Debugger.Object
  *        The object to describe with the created grip.
  */
 function objectSnapshot(aObject) {
   return {
     "type": "object",
     "class": aObject.class,
   };
 }
 /**
  * Create a (slightly more) detailed snapshot of the given debuggee object.
  *
  * @param aObject Debugger.Object
  *        The object to describe with the created descriptor.
  */
 function detailedObjectSnapshot(aObject) {
   let desc = objectSnapshot(aObject);
   let ownProperties = desc.ownProperties = Object.create(null);
   if (aObject.class == "DeadObject") {
     return desc;
   }
   let i = 0;
   for (let name of aObject.getOwnPropertyNames()) {
     if (i++ > MAX_PROPERTIES) {
       break;
     }
     let desc = propertySnapshot(name, aObject);
     if (desc) {
       ownProperties[name] = desc;
     }
   }
   return desc;
 }
 /**
  * A helper method that creates a snapshot of the object's |aName| property.
  *
  * @param aName string
  *        The property of which the snapshot is taken.
  *
  * @param aObject Debugger.Object
  *        The object whose property the snapshot is taken of.
  *
  * @return Object
  *         The snapshot of the property.
  */
 function propertySnapshot(aName, aObject) {
   let desc;
   try {
     desc = aObject.getOwnPropertyDescriptor(aName);
   } catch (e) {
     // Calling getOwnPropertyDescriptor on wrapped native prototypes is not
     // allowed (bug 560072). Inform the user with a bogus, but hopefully
     // explanatory, descriptor.
     return {
       configurable: false,
       writable: false,
       enumerable: false,
       value: e.name
     };
   }
   // Only create descriptors for simple values. We skip objects and properties
   // that have getters and setters; ain't nobody got time for that!
   if (!desc
       || typeof desc.value == "object" && desc.value !== null
       || !("value" in desc)) {
     return undefined;
   }
   return {
     configurable: desc.configurable,
     enumerable: desc.enumerable,
     writable: desc.writable,
     value: createValueSnapshot(desc.value)
   };
 }