Delivery logic for Object.observe

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 16 matching lines @@
 
 "use strict";
 
 var InternalObjectIsFrozen = $Object.isFrozen;
 var InternalObjectFreeze = $Object.freeze;
 
 var observationState = %GetObservationState();
 if (IS_UNDEFINED(observationState.observerInfoMap)) {
   observationState.observerInfoMap = %CreateObjectHashTable();
   observationState.objectInfoMap = %CreateObjectHashTable();
+  observationState.activeObservers = new InternalArray;
+  observationState.observerPriority = 0;
 }
 
 function InternalObjectHashTable(table) {
   this.table = table;
 }
 
 InternalObjectHashTable.prototype = {
   get: function(key) {
     return %ObjectHashTableGet(this.table, key);
   },
@@ skipping 11 matching lines @@
 
 function ObjectObserve(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)) {
-    // TODO: setup observerInfo.priority.
     observerInfoMap.set(callback, {
-      pendingChangeRecords: null
+      pendingChangeRecords: null,
+      priority: observationState.observerPriority++,
     });
   }
 
   var objectInfo = objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo)) {
     // TODO: setup objectInfo.notifier
     objectInfo = {
       changeObservers: new InternalArray(callback)
     };
     objectInfoMap.set(object, objectInfo);
@@ skipping 21 matching lines @@
   if (index < 0)
     return;
 
   changeObservers.splice(index, 1);
 }
 
 function EnqueueChangeRecord(changeRecord, observers) {
   for (var i = 0; i < observers.length; i++) {
     var observer = observers[i];
     var observerInfo = observerInfoMap.get(observer);
-
-    // TODO: "activate" the observer
-
-    if (IS_NULL(observerInfo.pendingChangeRecords)) {
-      observerInfo.pendingChangeRecords = new InternalArray(changeRecord);
+    observationState.activeObservers[observerInfo.priority] = observer;
+    %SetHasActiveObjectObservers();
+    var pendingChangeRecords = observerInfo.pendingChangeRecords;

[rossberg, 2012/11/06 16:45:57]

What is this variable used for?

[adamk, 2012/11/06 17:00:09]

Good question...removed.

+    if (IS_NULL(pendingChangeRecords)) {
+      pendingChangeRecords = observerInfo.pendingChangeRecords = new InternalArray(changeRecord);

[rossberg, 2012/11/06 16:45:57]

Line length

[adamk, 2012/11/06 17:00:09]

Done.

     } else {
       observerInfo.pendingChangeRecords.push(changeRecord);
     }
   }
 }
 
 function NotifyChange(type, object, name, oldValue) {
   var objectInfo = objectInfoMap.get(object);
   var changeRecord = (arguments.length < 4) ?
       { type: type, object: object, name: name } :
@@ skipping 17 matching lines @@
   for (var prop in changeRecord) {
     if (prop === 'object')
       continue;
     newRecord[prop] = changeRecord[prop];
   }
   InternalObjectFreeze(newRecord);
 
   EnqueueChangeRecord(newRecord, objectInfo.changeObservers);
 }
 
-function ObjectDeliverChangeRecords(callback) {
-  if (!IS_SPEC_FUNCTION(callback))
-    throw MakeTypeError("observe_non_function", ["deliverChangeRecords"]);
-
-  var observerInfo = observerInfoMap.get(callback);
+function DeliverChangeRecordsForObserver(observer) {
+  var observerInfo = observerInfoMap.get(observer);
   if (IS_UNDEFINED(observerInfo))
     return;
 
   var pendingChangeRecords = observerInfo.pendingChangeRecords;
   if (IS_NULL(pendingChangeRecords))
     return;
 
   observerInfo.pendingChangeRecords = null;
   var delivered = [];
   %MoveArrayContents(pendingChangeRecords, delivered);
   try {
-    %Call(void 0, delivered, callback);
+    %Call(void 0, delivered, observer);
   } catch (ex) {}
 }
 
+function ObjectDeliverChangeRecords(callback) {
+  if (!IS_SPEC_FUNCTION(callback))
+    throw MakeTypeError("observe_non_function", ["deliverChangeRecords"]);
+
+  DeliverChangeRecordsForObserver(callback);
+}
+
+function DeliverChangeRecords() {
+  while (observationState.activeObservers.length) {
+    var activeObservers = observationState.activeObservers;
+    observationState.activeObservers = new InternalArray;
+    for (var i in activeObservers) {
+      DeliverChangeRecordsForObserver(activeObservers[i]);
+    }
+  }
+}
+
 function SetupObjectObserve() {
   %CheckIsBootstrapping();
   InstallFunctions($Object, DONT_ENUM, $Array(
     "deliverChangeRecords", ObjectDeliverChangeRecords,
     "notify", ObjectNotify,  // TODO: Remove when getNotifier is implemented.
     "observe", ObjectObserve,
     "unobserve", ObjectUnobserve
   ));
 }
 
 SetupObjectObserve();