Revert "This patch implements optimized objectInfo structure which manages the...

Revert "This patch implements optimized objectInfo structure which manages the set of observers associated with an object and the changeRecord types which they accept."

This reverts r16539 as it triggers crashes on the GC stress bot.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16540 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/object-observe.js

@@ -27,41 +27,12 @@
 
 "use strict";
 
-// Overview:
-//
-// This file contains all of the routing and accounting for Object.observe.
-// User code will interact with these mechanisms via the Object.observe APIs
-// and, as a side effect of mutation objects which are observed. The V8 runtime
-// (both C++ and JS) will interact with these mechanisms primarily by enqueuing
-// proper change records for objects which were mutated. The Object.observe
-// routing and accounting consists primarily of three participants
-//
-// 1) ObjectInfo. This represents the observed state of a given object. It
-//    records what callbacks are observing the object, with what options, and
-//    what "change types" are in progress on the object (i.e. via
-//    notifier.performChange).
-//
-// 2) CallbackInfo. This represents a callback used for observation. It holds
-//    the records which must be delivered to the callback, as well as the global
-//    priority of the callback (which determines delivery order between
-//    callbacks).
-//
-// 3) observationState.pendingObservers. This is the set of observers which
-//    have change records which must be delivered. During "normal" delivery
-//    (i.e. not Object.deliverChangeRecords), this is the mechanism by which
-//    callbacks are invoked in the proper order until there are no more
-//    change records pending to a callback.
-//
-// Note that in order to reduce allocation and processing costs, the
-// implementation of (1) and (2) have "optimized" states which represent
-// common cases which can be handled more efficiently.
-
 var observationState = %GetObservationState();
 if (IS_UNDEFINED(observationState.callbackInfoMap)) {
   observationState.callbackInfoMap = %ObservationWeakMapCreate();
   observationState.objectInfoMap = %ObservationWeakMapCreate();
-  observationState.notifierObjectInfoMap = %ObservationWeakMapCreate();
-  observationState.pendingObservers = null;
+  observationState.notifierTargetMap = %ObservationWeakMapCreate();
+  observationState.pendingObservers = new InternalArray;
   observationState.nextCallbackPriority = 0;
 }
 
@@ -88,191 +59,126 @@ ObservationWeakMap.prototype = {
 var callbackInfoMap =
     new ObservationWeakMap(observationState.callbackInfoMap);
 var objectInfoMap = new ObservationWeakMap(observationState.objectInfoMap);
-var notifierObjectInfoMap =
-    new ObservationWeakMap(observationState.notifierObjectInfoMap);
+var notifierTargetMap =
+    new ObservationWeakMap(observationState.notifierTargetMap);
 
-function TypeMapCreate() {
-  return { __proto__: null };
+function CreateObjectInfo(object) {
+  var info = {
+    changeObservers: new InternalArray,
+    notifier: null,
+    inactiveObservers: new InternalArray,
+    performing: { __proto__: null },
+    performingCount: 0,
+  };
+  objectInfoMap.set(object, info);
+  return info;
 }
 
-function TypeMapAddType(typeMap, type, ignoreDuplicate) {
-  typeMap[type] = ignoreDuplicate ? 1 : (typeMap[type] || 0) + 1;
-}
+var defaultAcceptTypes = {
+  __proto__: null,
+  'new': true,
+  'updated': true,
+  'deleted': true,
+  'prototype': true,
+  'reconfigured': true
+};
 
-function TypeMapRemoveType(typeMap, type) {
-  typeMap[type]--;
-}
+function CreateObserver(callback, accept) {
+  var observer = {
+    __proto__: null,
+    callback: callback,
+    accept: defaultAcceptTypes
+  };
 
-function TypeMapCreateFromList(typeList) {
-  var typeMap = TypeMapCreate();
-  for (var i = 0; i < typeList.length; i++) {
-    TypeMapAddType(typeMap, typeList[i], true);
-  }
-  return typeMap;
-}
+  if (IS_UNDEFINED(accept))
+    return observer;
+
+  var acceptMap = { __proto__: null };
+  for (var i = 0; i < accept.length; i++)
+    acceptMap[accept[i]] = true;
 
-function TypeMapHasType(typeMap, type) {
-  return !!typeMap[type];
+  observer.accept = acceptMap;
+  return observer;
 }
 
-function TypeMapIsDisjointFrom(typeMap1, typeMap2) {
-  if (!typeMap1 || !typeMap2)
+function ObserverIsActive(observer, objectInfo) {
+  if (objectInfo.performingCount === 0)
     return true;
 
-  for (var type in typeMap1) {
-    if (TypeMapHasType(typeMap1, type) && TypeMapHasType(typeMap2, type))
+  var performing = objectInfo.performing;
+  for (var type in performing) {
+    if (performing[type] > 0 && observer.accept[type])
       return false;
   }
 
   return true;
 }
 
-var defaultAcceptTypes = TypeMapCreateFromList([
-  'new',
-  'updated',
-  'deleted',
-  'prototype',
-  'reconfigured'
-]);
-
-// An Observer is a registration to observe an object by a callback with
-// a given set of accept types. If the set of accept types is the default
-// set for Object.observe, the observer is represented as a direct reference
-// to the callback. An observer never changes its accept types and thus never
-// needs to "normalize".
-function ObserverCreate(callback, acceptList) {
-  return IS_UNDEFINED(acceptList) ? callback : {
-    __proto__: null,
-    callback: callback,
-    accept: TypeMapCreateFromList(acceptList)
-  };
-}
-
-function ObserverGetCallback(observer) {
-  return IS_SPEC_FUNCTION(observer) ? observer : observer.callback;
-}
-
-function ObserverGetAcceptTypes(observer) {
-  return IS_SPEC_FUNCTION(observer) ? defaultAcceptTypes : observer.accept;
+function ObserverIsInactive(observer, objectInfo) {
+  return !ObserverIsActive(observer, objectInfo);
 }
 
-function ObserverIsActive(observer, objectInfo) {
-  return TypeMapIsDisjointFrom(ObjectInfoGetPerformingTypes(objectInfo),
-                               ObserverGetAcceptTypes(observer));
-}
-
-function ObjectInfoGet(object) {
-  var objectInfo = objectInfoMap.get(object);
-  if (IS_UNDEFINED(objectInfo)) {
-    if (!%IsJSProxy(object))
-      %SetIsObserved(object);
-
-    objectInfo = {
-      object: object,
-      changeObservers: null,
-      notifier: null,
-      performing: null,
-      performingCount: 0,
-    };
-    objectInfoMap.set(object, objectInfo);
+function RemoveNullElements(from) {
+  var i = 0;
+  var j = 0;
+  for (; i < from.length; i++) {
+    if (from[i] === null)
+      continue;
+    if (j < i)
+      from[j] = from[i];
+    j++;
   }
-  return objectInfo;
-}
 
-function ObjectInfoGetFromNotifier(notifier) {
-  return notifierObjectInfoMap.get(notifier);
+  if (i !== j)
+    from.length = from.length - (i - j);
 }
 
-function ObjectInfoGetNotifier(objectInfo) {
-  if (IS_NULL(objectInfo.notifier)) {
-    objectInfo.notifier = { __proto__: notifierPrototype };
-    notifierObjectInfoMap.set(objectInfo.notifier, objectInfo);
+function RepartitionObservers(conditionFn, from, to, objectInfo) {
+  var anyRemoved = false;
+  for (var i = 0; i < from.length; i++) {
+    var observer = from[i];
+    if (conditionFn(observer, objectInfo)) {
+      anyRemoved = true;
+      from[i] = null;
+      to.push(observer);
+    }
   }
 
-  return objectInfo.notifier;
-}
-
-function ObjectInfoGetObject(objectInfo) {
-  return objectInfo.object;
+  if (anyRemoved)
+    RemoveNullElements(from);
 }
 
-function ChangeObserversIsOptimized(changeObservers) {
-  return typeof changeObservers === 'function' ||
-         typeof changeObservers.callback === 'function';
+function BeginPerformChange(objectInfo, type) {
+  objectInfo.performing[type] = (objectInfo.performing[type] || 0) + 1;
+  objectInfo.performingCount++;
+  RepartitionObservers(ObserverIsInactive,
+                       objectInfo.changeObservers,
+                       objectInfo.inactiveObservers,
+                       objectInfo);
 }
 
-// The set of observers on an object is called 'changeObservers'. The first
-// observer is referenced directly via objectInfo.changeObservers. When a second
-// is added, changeObservers "normalizes" to become a mapping of callback
-// priority -> observer and is then stored on objectInfo.changeObservers.
-function ObjectInfoNormalizeChangeObservers(objectInfo) {
-  if (ChangeObserversIsOptimized(objectInfo.changeObservers)) {
-    var observer = objectInfo.changeObservers;
-    var callback = ObserverGetCallback(observer);
-    var callbackInfo = CallbackInfoGet(callback);
-    var priority = CallbackInfoGetPriority(callbackInfo);
-    objectInfo.changeObservers = { __proto__: null };
-    objectInfo.changeObservers[priority] = observer;
-  }
+function EndPerformChange(objectInfo, type) {
+  objectInfo.performing[type]--;
+  objectInfo.performingCount--;
+  RepartitionObservers(ObserverIsActive,
+                       objectInfo.inactiveObservers,
+                       objectInfo.changeObservers,
+                       objectInfo);
 }
 
-function ObjectInfoAddObserver(objectInfo, callback, acceptList) {
-  var callbackInfo = CallbackInfoGetOrCreate(callback);
-  var observer = ObserverCreate(callback, acceptList);
-
-  if (!objectInfo.changeObservers) {
-    objectInfo.changeObservers = observer;
-    return;
+function EnsureObserverRemoved(objectInfo, callback) {
+  function remove(observerList) {
+    for (var i = 0; i < observerList.length; i++) {
+      if (observerList[i].callback === callback) {
+        observerList.splice(i, 1);
+        return true;
       }
-
-  ObjectInfoNormalizeChangeObservers(objectInfo);
-  var priority = CallbackInfoGetPriority(callbackInfo);
-  objectInfo.changeObservers[priority] = observer;
-}
-
-function ObjectInfoRemoveObserver(objectInfo, callback) {
-  if (!objectInfo.changeObservers)
-    return;
-
-  if (ChangeObserversIsOptimized(objectInfo.changeObservers)) {
-    if (callback === ObserverGetCallback(objectInfo.changeObservers))
-      objectInfo.changeObservers = null;
-    return;
     }
-
-  var callbackInfo = CallbackInfoGet(callback);
-  var priority = CallbackInfoGetPriority(callbackInfo);
-  delete objectInfo.changeObservers[priority];
-}
-
-function ObjectInfoHasActiveObservers(objectInfo) {
-  if (IS_UNDEFINED(objectInfo) || !objectInfo.changeObservers)
     return false;
-
-  if (ChangeObserversIsOptimized(objectInfo.changeObservers))
-    return ObserverIsActive(objectInfo.changeObservers, objectInfo);
-
-  for (var priority in objectInfo.changeObservers) {
-    if (ObserverIsActive(objectInfo.changeObservers[priority], objectInfo))
-      return true;
   }
 
-  return false;
-}
-
-function ObjectInfoAddPerformingType(objectInfo, type) {
-  objectInfo.performing = objectInfo.performing || TypeMapCreate();
-  TypeMapAddType(objectInfo.performing, type);
-  objectInfo.performingCount++;
-}
-
-function ObjectInfoRemovePerformingType(objectInfo, type) {
-  objectInfo.performingCount--;
-  TypeMapRemoveType(objectInfo.performing, type);
-}
-
-function ObjectInfoGetPerformingTypes(objectInfo) {
-  return objectInfo.performingCount > 0 ? objectInfo.performing : null;
+  if (!remove(objectInfo.changeObservers))
+    remove(objectInfo.inactiveObservers);
 }
 
 function AcceptArgIsValid(arg) {
@@ -292,31 +198,12 @@ function AcceptArgIsValid(arg) {
   return true;
 }
 
-// CallbackInfo's optimized state is just a number which represents its global
-// priority. When a change record must be enqueued for the callback, it
-// normalizes. When delivery clears any pending change records, it re-optimizes.
-function CallbackInfoGet(callback) {
-  return callbackInfoMap.get(callback);
-}
-
-function CallbackInfoGetOrCreate(callback) {
-  var callbackInfo = callbackInfoMap.get(callback);
-  if (!IS_UNDEFINED(callbackInfo))
-    return callbackInfo;
-
-  var priority = observationState.nextCallbackPriority++
-  callbackInfoMap.set(callback, priority);
-  return priority;
-}
-
-function CallbackInfoGetPriority(callbackInfo) {
-  if (IS_NUMBER(callbackInfo))
-    return callbackInfo;
-  else
-    return callbackInfo.priority;
+function EnsureCallbackPriority(callback) {
+  if (!callbackInfoMap.has(callback))
+    callbackInfoMap.set(callback, observationState.nextCallbackPriority++);
 }
 
-function CallbackInfoNormalize(callback) {
+function NormalizeCallbackInfo(callback) {
   var callbackInfo = callbackInfoMap.get(callback);
   if (IS_NUMBER(callbackInfo)) {
     var priority = callbackInfo;
@@ -327,18 +214,32 @@ function CallbackInfoNormalize(callback) {
   return callbackInfo;
 }
 
-function ObjectObserve(object, callback, acceptList) {
+function ObjectObserve(object, callback, accept) {
   if (!IS_SPEC_OBJECT(object))
     throw MakeTypeError("observe_non_object", ["observe"]);
   if (!IS_SPEC_FUNCTION(callback))
     throw MakeTypeError("observe_non_function", ["observe"]);
   if (ObjectIsFrozen(callback))
     throw MakeTypeError("observe_callback_frozen");
-  if (!AcceptArgIsValid(acceptList))
+  if (!AcceptArgIsValid(accept))
     throw MakeTypeError("observe_accept_invalid");
 
-  var objectInfo = ObjectInfoGet(object);
-  ObjectInfoAddObserver(objectInfo, callback, acceptList);
+  EnsureCallbackPriority(callback);
+
+  var objectInfo = objectInfoMap.get(object);
+  if (IS_UNDEFINED(objectInfo)) {
+    objectInfo = CreateObjectInfo(object);
+    %SetIsObserved(object);
+  }
+
+  EnsureObserverRemoved(objectInfo, callback);
+
+  var observer = CreateObserver(callback, accept);
+  if (ObserverIsActive(observer, objectInfo))
+    objectInfo.changeObservers.push(observer);
+  else
+    objectInfo.inactiveObservers.push(observer);
+
   return object;
 }
 
@@ -352,7 +253,7 @@ function ObjectUnobserve(object, callback) {
   if (IS_UNDEFINED(objectInfo))
     return object;
 
-  ObjectInfoRemoveObserver(objectInfo, callback);
+  EnsureObserverRemoved(objectInfo, callback);
   return object;
 }
 
@@ -367,52 +268,41 @@ function ArrayUnobserve(object, callback) {
   return ObjectUnobserve(object, callback);
 }
 
-function ObserverEnqueueIfActive(observer, objectInfo, changeRecord) {
-  if (!ObserverIsActive(observer, objectInfo) ||
-      !TypeMapHasType(ObserverGetAcceptTypes(observer), changeRecord.type)) {
-    return;
-  }
-
-  var callback = ObserverGetCallback(observer);
-  var callbackInfo = CallbackInfoNormalize(callback);
-  if (!observationState.pendingObservers)
-    observationState.pendingObservers = { __proto__: null };
+function EnqueueToCallback(callback, changeRecord) {
+  var callbackInfo = NormalizeCallbackInfo(callback);
   observationState.pendingObservers[callbackInfo.priority] = callback;
   callbackInfo.push(changeRecord);
   %SetObserverDeliveryPending();
 }
 
-function ObjectInfoEnqueueChangeRecord(objectInfo, changeRecord) {
+function EnqueueChangeRecord(changeRecord, observers) {
   // TODO(rossberg): adjust once there is a story for symbols vs proxies.
   if (IS_SYMBOL(changeRecord.name)) return;
 
-  if (ChangeObserversIsOptimized(objectInfo.changeObservers)) {
-    var observer = objectInfo.changeObservers;
-    ObserverEnqueueIfActive(observer, objectInfo, changeRecord);
-    return;
-  }
+  for (var i = 0; i < observers.length; i++) {
+    var observer = observers[i];
+    if (IS_UNDEFINED(observer.accept[changeRecord.type]))
+      continue;
 
-  for (var priority in objectInfo.changeObservers) {
-    var observer = objectInfo.changeObservers[priority];
-    ObserverEnqueueIfActive(observer, objectInfo, changeRecord);
+    EnqueueToCallback(observer.callback, changeRecord);
   }
 }
 
 function BeginPerformSplice(array) {
   var objectInfo = objectInfoMap.get(array);
   if (!IS_UNDEFINED(objectInfo))
-    ObjectInfoAddPerformingType(objectInfo, 'splice');
+    BeginPerformChange(objectInfo, 'splice');
 }
 
 function EndPerformSplice(array) {
   var objectInfo = objectInfoMap.get(array);
   if (!IS_UNDEFINED(objectInfo))
-    ObjectInfoRemovePerformingType(objectInfo, 'splice');
+    EndPerformChange(objectInfo, 'splice');
 }
 
 function EnqueueSpliceRecord(array, index, removed, addedCount) {
   var objectInfo = objectInfoMap.get(array);
-  if (!ObjectInfoHasActiveObservers(objectInfo))
+  if (IS_UNDEFINED(objectInfo) || objectInfo.changeObservers.length === 0)
     return;
 
   var changeRecord = {
@@ -425,19 +315,19 @@ function EnqueueSpliceRecord(array, index, removed, addedCount) {
 
   ObjectFreeze(changeRecord);
   ObjectFreeze(changeRecord.removed);
-  ObjectInfoEnqueueChangeRecord(objectInfo, changeRecord);
+  EnqueueChangeRecord(changeRecord, objectInfo.changeObservers);
 }
 
 function NotifyChange(type, object, name, oldValue) {
   var objectInfo = objectInfoMap.get(object);
-  if (!ObjectInfoHasActiveObservers(objectInfo))
+  if (objectInfo.changeObservers.length === 0)
     return;
 
   var changeRecord = (arguments.length < 4) ?
       { type: type, object: object, name: name } :
       { type: type, object: object, name: name, oldValue: oldValue };
   ObjectFreeze(changeRecord);
-  ObjectInfoEnqueueChangeRecord(objectInfo, changeRecord);
+  EnqueueChangeRecord(changeRecord, objectInfo.changeObservers);
 }
 
 var notifierPrototype = {};
@@ -446,16 +336,17 @@ function ObjectNotifierNotify(changeRecord) {
   if (!IS_SPEC_OBJECT(this))
     throw MakeTypeError("called_on_non_object", ["notify"]);
 
-  var objectInfo = ObjectInfoGetFromNotifier(this);
-  if (IS_UNDEFINED(objectInfo))
+  var target = notifierTargetMap.get(this);
+  if (IS_UNDEFINED(target))
     throw MakeTypeError("observe_notify_non_notifier");
   if (!IS_STRING(changeRecord.type))
     throw MakeTypeError("observe_type_non_string");
 
-  if (!ObjectInfoHasActiveObservers(objectInfo))
+  var objectInfo = objectInfoMap.get(target);
+  if (IS_UNDEFINED(objectInfo) || objectInfo.changeObservers.length === 0)
     return;
 
-  var newRecord = { object: ObjectInfoGetObject(objectInfo) };
+  var newRecord = { object: target };
   for (var prop in changeRecord) {
     if (prop === 'object') continue;
     %DefineOrRedefineDataProperty(newRecord, prop, changeRecord[prop],
@@ -463,16 +354,15 @@ function ObjectNotifierNotify(changeRecord) {
   }
   ObjectFreeze(newRecord);
 
-  ObjectInfoEnqueueChangeRecord(objectInfo, newRecord);
+  EnqueueChangeRecord(newRecord, objectInfo.changeObservers);
 }
 
 function ObjectNotifierPerformChange(changeType, changeFn, receiver) {
   if (!IS_SPEC_OBJECT(this))
     throw MakeTypeError("called_on_non_object", ["performChange"]);
 
-  var objectInfo = ObjectInfoGetFromNotifier(this);
-
-  if (IS_UNDEFINED(objectInfo))
+  var target = notifierTargetMap.get(this);
+  if (IS_UNDEFINED(target))
     throw MakeTypeError("observe_notify_non_notifier");
   if (!IS_STRING(changeType))
     throw MakeTypeError("observe_perform_non_string");
@@ -485,11 +375,15 @@ function ObjectNotifierPerformChange(changeType, changeFn, receiver) {
     receiver = ToObject(receiver);
   }
 
-  ObjectInfoAddPerformingType(objectInfo, changeType);
+  var objectInfo = objectInfoMap.get(target);
+  if (IS_UNDEFINED(objectInfo))
+    return;
+
+  BeginPerformChange(objectInfo, changeType);
   try {
     %_CallFunction(receiver, changeFn);
   } finally {
-    ObjectInfoRemovePerformingType(objectInfo, changeType);
+    EndPerformChange(objectInfo, changeType);
   }
 }
 
@@ -499,8 +393,18 @@ function ObjectGetNotifier(object) {
 
   if (ObjectIsFrozen(object)) return null;
 
-  var objectInfo = ObjectInfoGet(object);
-  return ObjectInfoGetNotifier(objectInfo);
+  var objectInfo = objectInfoMap.get(object);
+  if (IS_UNDEFINED(objectInfo)) {
+    objectInfo = CreateObjectInfo(object);
+    %SetIsObserved(object);
+  }
+
+  if (IS_NULL(objectInfo.notifier)) {
+    objectInfo.notifier = { __proto__: notifierPrototype };
+    notifierTargetMap.set(objectInfo.notifier, object);
+  }
+
+  return objectInfo.notifier;
 }
 
 function CallbackDeliverPending(callback) {
@@ -513,9 +417,7 @@ function CallbackDeliverPending(callback) {
   var priority = callbackInfo.priority;
   callbackInfoMap.set(callback, priority);
 
-  if (observationState.pendingObservers)
   delete observationState.pendingObservers[priority];
-
   var delivered = [];
   %MoveArrayContents(callbackInfo, delivered);
 
@@ -533,9 +435,9 @@ function ObjectDeliverChangeRecords(callback) {
 }
 
 function DeliverChangeRecords() {
-  while (observationState.pendingObservers) {
+  while (observationState.pendingObservers.length) {
     var pendingObservers = observationState.pendingObservers;
-    observationState.pendingObservers = null;
+    observationState.pendingObservers = new InternalArray;
     for (var i in pendingObservers) {
       CallbackDeliverPending(pendingObservers[i]);
     }

test/cctest/test-object-observe.cc

@@ -435,14 +435,14 @@ TEST(ObservationWeakMap) {
   i::Handle<i::JSWeakMap> objectInfoMap =
       i::Handle<i::JSWeakMap>::cast(
           i::GetProperty(observation_state, "objectInfoMap"));
-  i::Handle<i::JSWeakMap> notifierObjectInfoMap =
+  i::Handle<i::JSWeakMap> notifierTargetMap =
       i::Handle<i::JSWeakMap>::cast(
-          i::GetProperty(observation_state, "notifierObjectInfoMap"));
+          i::GetProperty(observation_state, "notifierTargetMap"));
   CHECK_EQ(1, NumberOfElements(callbackInfoMap));
   CHECK_EQ(1, NumberOfElements(objectInfoMap));
-  CHECK_EQ(1, NumberOfElements(notifierObjectInfoMap));
+  CHECK_EQ(1, NumberOfElements(notifierTargetMap));
   HEAP->CollectAllGarbage(i::Heap::kAbortIncrementalMarkingMask);
   CHECK_EQ(0, NumberOfElements(callbackInfoMap));
   CHECK_EQ(0, NumberOfElements(objectInfoMap));
-  CHECK_EQ(0, NumberOfElements(notifierObjectInfoMap));
+  CHECK_EQ(0, NumberOfElements(notifierTargetMap));
 }