Remove unmarked entries from per context map caches.

src/factory.cc

 // Copyright 2011 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 1150 matching lines @@
 
 MUST_USE_RESULT static MaybeObject* UpdateMapCacheWith(Context* context,
                                                        FixedArray* keys,
                                                        Map* map) {
   Object* result;
   { MaybeObject* maybe_result =
         MapCache::cast(context->map_cache())->Put(keys, map);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
   context->set_map_cache(MapCache::cast(result));
+  StatsCounter* counter =
+      Isolate::Current()->counters()->max_map_cache_length();
+  int length = FixedArray::cast(result)->length();
+  if (counter->Enabled() && (*counter->GetInternalPointer()) < length) {
+    counter->Set(length);
+  }
   return result;
 }
 
 
 Handle<MapCache> Factory::AddToMapCache(Handle<Context> context,
                                         Handle<FixedArray> keys,
                                         Handle<Map> map) {
   CALL_HEAP_FUNCTION(isolate(),
                      UpdateMapCacheWith(*context, *keys, *map), MapCache);
 }
 
 
 Handle<Map> Factory::ObjectLiteralMapFromCache(Handle<Context> context,
                                                Handle<FixedArray> keys) {
   if (context->map_cache()->IsUndefined()) {
     // Allocate the new map cache for the global context.
     Handle<MapCache> new_cache = NewMapCache(24);
     context->set_map_cache(*new_cache);
   }
   // Check to see whether there is a matching element in the cache.
   Handle<MapCache> cache =
       Handle<MapCache>(MapCache::cast(context->map_cache()));
   Handle<Object> result = Handle<Object>(cache->Lookup(*keys));
-  if (result->IsMap()) return Handle<Map>::cast(result);
+  if (result->IsMap()) {
+    Isolate::Current()->counters()->map_cache_hits()->Increment();
+    return Handle<Map>::cast(result);
+  }
+  Isolate::Current()->counters()->map_cache_misses()->Increment();
   // Create a new map and add it to the cache.
   Handle<Map> map =
       CopyMap(Handle<Map>(context->object_function()->initial_map()),
               keys->length());
   AddToMapCache(context, keys, map);
   return Handle<Map>(map);
 }
 
 
 void Factory::SetRegExpAtomData(Handle<JSRegExp> regexp,
@@ skipping 40 matching lines @@
     Execution::ConfigureInstance(instance,
                                  instance_template,
                                  pending_exception);
   } else {
     *pending_exception = false;
   }
 }
 
 
 } }  // namespace v8::internal