Store Object.observe state per-isolate rather than per-context

src/object-observe.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 25 matching lines @@
   get: $WeakMap.prototype.get,
   has: $WeakMap.prototype.has
 }
 
 function createInternalWeakMap() {
   var map = new $WeakMap;
   map.__proto__ = InternalWeakMapProto;
   return map;
 }
 
-var observerInfoMap = createInternalWeakMap();
-var objectInfoMap = createInternalWeakMap();
+function GetOrCreateObjectObservationState() {
+  var state = %GetObjectObservationState();
+  if (IS_UNDEFINED(state.observerInfoMap)) {
+    state.observerInfoMap = createInternalWeakMap();
+    state.objectInfoMap = createInternalWeakMap();
+  }
+  return state;
+}
 

[rafaelw, 2012/10/24 15:21:35]

suggestion:

var state = %GetObjectObservationState();
if (IS_UNDEFINED(state.observerInfoMap)) {
 state.observerInfoMap = createInternalWeakMap();
 state.objectInfoMap = createInternalWeakMap();
}

var observerInfoMap = state.observerInfoMap;
var objectInfoMap = state.objectInfoMap;

[adamk, 2012/10/24 15:50:38]

Done.

 $Object.observe = function(object, callback) {
 
   if (!IS_SPEC_OBJECT(object))
     throw MakeTypeError("observe_non_object", ["observe"]);
   if (!IS_SPEC_FUNCTION(callback))
     throw MakeTypeError("observe_non_function", ["observe"]);
   if (InternalObjectIsFrozen(callback))
     throw MakeTypeError("observe_callback_frozen");
 
-  if (!observerInfoMap.has(callback)) {
+  var state = GetOrCreateObjectObservationState();
+  if (!state.observerInfoMap.has(callback)) {
     // TODO: setup observerInfo.priority.
-    observerInfoMap.set(callback, {
+    state.observerInfoMap.set(callback, {
       pendingChangeRecords: null
     });
   }
 
-  var objectInfo = objectInfoMap.get(object);
+  var objectInfo = state.objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo)) {
     // TODO: setup objectInfo.notifier
     objectInfo = {
       changeObservers: new InternalArray(callback)
     };
-    objectInfoMap.set(object, objectInfo);
+    state.objectInfoMap.set(object, objectInfo);
     return;
   }
 
   var changeObservers = objectInfo.changeObservers;
   if (changeObservers.indexOf(callback) >= 0)
     return;
 
   changeObservers.push(callback);
 }
 
 $Object.unobserve = function(object, callback) {
   if (!IS_SPEC_OBJECT(object))
     throw MakeTypeError("observe_non_object", ["unobserve"]);
 
-  var objectInfo = objectInfoMap.get(object);
+  var state = GetOrCreateObjectObservationState();
+  var objectInfo = state.objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo))
     return;
 
-  var observerInfo = observerInfoMap.get(callback);
+  var observerInfo = state.observerInfoMap.get(callback);
 
   var changeObservers = objectInfo.changeObservers;
   var index = changeObservers.indexOf(callback);
   if (index < 0)
     return;
 
   changeObservers.splice(index, 1);
 }
 
-function EnqueueChangeRecord(changeRecord, observers) {
+function EnqueueChangeRecord(changeRecord, observers, state) {
   for (var i = 0; i < observers.length; i++) {
     var observer = observers[i];
-    var observerInfo = observerInfoMap.get(observer);
+    var observerInfo = state.observerInfoMap.get(observer);
 
     // TODO: "activate" the observer
 
     var pendingChangeRecords = observerInfo.pendingChangeRecords;
     if (IS_NULL(pendingChangeRecords)) {
       pendingChangeRecords = observerInfo.pendingChangeRecords = new InternalArray(changeRecord);
     } else {
       pendingChangeRecords.push(changeRecord);
     }
   }
 }
 
 $Object.notify = function(object, changeRecord) {
   // TODO: notifier needs to be [[THIS]]
   if (!IS_STRING(changeRecord.type))
     throw MakeTypeError("observe_type_non_string");
 
-  var objectInfo = objectInfoMap.get(object);
+  var state = GetOrCreateObjectObservationState();
+  var objectInfo = state.objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo))
     return;
 
   var newRecord = {
     object: object  // TODO: Needs to be 'object' retreived from notifier
   };
   for (var prop in changeRecord) {
     if (prop === 'object')
       continue;
     newRecord[prop] = changeRecord[prop];
   }
   InternalObjectFreeze(newRecord);
 
-  EnqueueChangeRecord(newRecord, objectInfo.changeObservers);
+  EnqueueChangeRecord(newRecord, objectInfo.changeObservers, state);
 }
 
 $Object.deliverChangeRecords = function(callback) {
   if (!IS_SPEC_FUNCTION(callback))
     throw MakeTypeError("observe_non_function", ["deliverChangeRecords"]);
 
-  var observerInfo = observerInfoMap.get(callback);
+  var state = GetOrCreateObjectObservationState();
+  var observerInfo = state.observerInfoMap.get(callback);
   if (IS_UNDEFINED(observerInfo))
     return;
 
   var pendingChangeRecords = observerInfo.pendingChangeRecords;
   if (IS_NULL(pendingChangeRecords))
     return;
 
   observerInfo.pendingChangeRecords = null;
   var delivered = [];
   %MoveArrayContents(pendingChangeRecords, delivered);
   callback(delivered);
-}
+}