Bug 1506469 - Allow inspecting objects logged to the console without switching to a replaying child, r=lsmyth.

--HG--
extra : rebase_source : 4e00da50edb5eeb8e5d9c490e893e6bddb47a440

devtools/server/actors/replay/debugger.js

@@ -243,12 +243,15 @@ ReplayDebugger.prototype = {
   // Object methods
   /////////////////////////////////////////////////////////
 
-  _getObject(id) {
+  // Objects which |forConsole| is set are objects that were logged in console
+  // messages, and had their properties recorded so that they can be inspected
+  // without switching to a replaying child.
+  _getObject(id, forConsole) {
     if (id && !this._objects[id]) {
       const data = this._sendRequest({ type: "getObject", id });
       switch (data.kind) {
       case "Object":
-        this._objects[id] = new ReplayDebuggerObject(this, data);
+        this._objects[id] = new ReplayDebuggerObject(this, data, forConsole);
         break;
       case "Environment":
         this._objects[id] = new ReplayDebuggerEnvironment(this, data);
@@ -257,13 +260,17 @@ ReplayDebugger.prototype = {
         ThrowError("Unknown object kind");
       }
     }
-    return this._objects[id];
+    const rv = this._objects[id];
+    if (forConsole) {
+      rv._forConsole = true;
+    }
+    return rv;
   },
 
-  _convertValue(value) {
-    if (value && typeof value == "object") {
+  _convertValue(value, forConsole) {
+    if (isNonNullObject(value)) {
       if (value.object) {
-        return this._getObject(value.object);
+        return this._getObject(value.object, forConsole);
       } else if (value.special == "undefined") {
         return undefined;
       } else if (value.special == "NaN") {
@@ -332,7 +339,8 @@ ReplayDebugger.prototype = {
     // other contents of the message can be left alone.
     if (message.messageType == "ConsoleAPI" && message.arguments) {
       for (let i = 0; i < message.arguments.length; i++) {
-        message.arguments[i] = this._convertValue(message.arguments[i]);
+        message.arguments[i] = this._convertValue(message.arguments[i],
+                                                  /* forConsole = */ true);
       }
     }
     return message;
@@ -497,7 +505,7 @@ function ReplayDebuggerFrame(dbg, data) {
   this._data = data;
   if (this._data.arguments) {
     this._data.arguments =
-      this._data.arguments.map(this._dbg._convertValue.bind(this._dbg));
+      this._data.arguments.map(a => this._dbg._convertValue(a));
   }
 }
 
@@ -606,9 +614,10 @@ ReplayDebuggerFrame.prototype = {
 // ReplayDebuggerObject
 ///////////////////////////////////////////////////////////////////////////////
 
-function ReplayDebuggerObject(dbg, data) {
+function ReplayDebuggerObject(dbg, data, forConsole) {
   this._dbg = dbg;
   this._data = data;
+  this._forConsole = forConsole;
   this._properties = null;
 }
 
@@ -623,7 +632,6 @@ ReplayDebuggerObject.prototype = {
   get isArrowFunction() { return this._data.isArrowFunction; },
   get isGeneratorFunction() { return this._data.isGeneratorFunction; },
   get isAsyncFunction() { return this._data.isAsyncFunction; },
-  get proto() { return this._dbg._getObject(this._data.proto); },
   get class() { return this._data.class; },
   get name() { return this._data.name; },
   get displayName() { return this._data.displayName; },
@@ -641,6 +649,13 @@ ReplayDebuggerObject.prototype = {
   isFrozen() { return this._data.isFrozen; },
   unwrap() { return this.isProxy ? NYI() : this; },
 
+  get proto() {
+    // Don't allow inspection of the prototypes of objects logged to the
+    // console. This is a hack that prevents the object inspector from crawling
+    // the object's prototype chain.
+    return this._forConsole ? null : this._dbg._getObject(this._data.proto);
+  },
+
   unsafeDereference() {
     // Direct access to the referent is not currently available.
     return null;
@@ -664,10 +679,10 @@ ReplayDebuggerObject.prototype = {
 
   _ensureProperties() {
     if (!this._properties) {
-      const properties = this._dbg._sendRequestAllowDiverge({
-        type: "getObjectProperties",
-        id: this._data.id,
-      });
+      const id = this._data.id;
+      const properties = this._forConsole
+        ? this._dbg._sendRequest({ type: "getObjectPropertiesForConsole", id })
+        : this._dbg._sendRequestAllowDiverge({ type: "getObjectProperties", id });
       this._properties = {};
       properties.forEach(({name, desc}) => { this._properties[name] = desc; });
     }
@@ -791,4 +806,8 @@ function assert(v) {
   }
 }
 
+function isNonNullObject(obj) {
+  return obj && (typeof obj == "object" || typeof obj == "function");
+}
+
 module.exports = ReplayDebugger;

devtools/server/actors/replay/replay.js

@@ -116,6 +116,10 @@ function scriptFrameForIndex(index) {
   return frame;
 }
 
+function isNonNullObject(obj) {
+  return obj && (typeof obj == "object" || typeof obj == "function");
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Persistent Script State
 ///////////////////////////////////////////////////////////////////////////////
@@ -179,6 +183,26 @@ dbg.onNewScript = function(script) {
   installPendingHandlers();
 };
 
+const gConsoleObjectProperties = new Map();
+
+function shouldSaveConsoleProperty({ desc }) {
+  // When logging an object to the console, only properties captured here will
+  // be shown. We limit this to non-object data properties, as more complex
+  // properties have two problems: A) to inspect them we will need to switch to
+  // a replaying child process, which is very slow when there are many console
+  // messages, and B) trying to access objects transitively referred to by
+  // logged console objects will fail when unpaused, and depends on the current
+  // state of the process otherwise.
+  return "value" in desc && !isNonNullObject(desc.value);
+}
+
+function saveConsoleObjectProperties(obj) {
+  if (obj instanceof Debugger.Object) {
+    const properties = getObjectProperties(obj).filter(shouldSaveConsoleProperty);
+    gConsoleObjectProperties.set(obj, properties);
+  }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Console Message State
 ///////////////////////////////////////////////////////////////////////////////
@@ -250,6 +274,7 @@ Services.obs.addObserver({
     // Message arguments are preserved as debuggee values.
     if (apiMessage.arguments) {
       contents.arguments = apiMessage.arguments.map(makeDebuggeeValue);
+      contents.arguments.forEach(saveConsoleObjectProperties);
     }
 
     newConsoleMessage("ConsoleAPI", null, contents);
@@ -465,7 +490,7 @@ function convertCompletionValue(value) {
 }
 
 function makeDebuggeeValue(value) {
-  if (value && typeof value == "object") {
+  if (isNonNullObject(value)) {
     assert(!(value instanceof Debugger.Object));
     const global = Cu.getGlobalForObject(value);
     const dbgGlobal = dbg.makeGlobalObjectReference(global);
@@ -517,6 +542,24 @@ function forwardToScript(name) {
   return request => gScripts.getObject(request.id)[name](request.value);
 }
 
+function getObjectProperties(object) {
+  const names = object.getOwnPropertyNames();
+
+  return names.map(name => {
+    const desc = object.getOwnPropertyDescriptor(name);
+    if ("value" in desc) {
+      desc.value = convertValue(desc.value);
+    }
+    if ("get" in desc) {
+      desc.get = getObjectId(desc.get);
+    }
+    if ("set" in desc) {
+      desc.set = getObjectId(desc.set);
+    }
+    return { name, desc };
+  });
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Handlers
 ///////////////////////////////////////////////////////////////////////////////
@@ -626,21 +669,16 @@ const gRequestHandlers = {
     }
 
     const object = gPausedObjects.getObject(request.id);
-    const names = object.getOwnPropertyNames();
+    return getObjectProperties(object);
+  },
 
-    return names.map(name => {
-      const desc = object.getOwnPropertyDescriptor(name);
-      if ("value" in desc) {
-        desc.value = convertValue(desc.value);
-      }
-      if ("get" in desc) {
-        desc.get = getObjectId(desc.get);
-      }
-      if ("set" in desc) {
-        desc.set = getObjectId(desc.set);
-      }
-      return { name, desc };
-    });
+  getObjectPropertiesForConsole(request) {
+    const object = gPausedObjects.getObject(request.id);
+    const properties = gConsoleObjectProperties.get(object);
+    if (!properties) {
+      throw new Error("Console object properties not saved");
+    }
+    return properties;
   },
 
   getEnvironmentNames(request) {