Changeset 54696 in webkit for trunk/JavaScriptCore/runtime/JSPropertyNameIterator.h

Timestamp:

Feb 11, 2010, 6:51:35 PM (15 years ago)

Author:

[email protected]

Message:

2010-02-11 Geoffrey Garen <​[email protected]>

Reviewed by Gavin Barraclough.

Some progress toward fixing
​https://bugs.webkit.org/show_bug.cgi?id=34864 | <rdar://problem/7594198>
Many objects left uncollected after visiting mail.google.com and closing
window

SunSpider reports no change.

Keep weak references, rather than protected references, to cached for-in
property name enumerators.

One problem with protected references is that a chain like

[ gc object 1 ] => [ non-gc object ] => [ gc object 2 ]

takes two GC passes to break, since the first pass collects [ gc object 1 ],
releasing [ non-gc object ] and unprotecting [ gc object 2 ], and only
then can a second pass collect [ gc object 2 ].

Another problem with protected references is that they can keep a bunch
of strings alive long after they're useful. In SunSpider and a few popular
websites, the size-speed tradeoff seems to favor weak references.

• runtime/JSPropertyNameIterator.cpp: (JSC::JSPropertyNameIterator::JSPropertyNameIterator): Moved this constructor into the .cpp file, since it's not used elsewhere.

(JSC::JSPropertyNameIterator::~JSPropertyNameIterator): Added a destructor
to support our weak reference.

• runtime/JSPropertyNameIterator.h: (JSC::Structure::setEnumerationCache): (JSC::Structure::clearEnumerationCache): (JSC::Structure::enumerationCache): Added a function for clearing a Structure's enumeration cache, used by our new destructor. Also fixed indentation to match the rest of the file.

• runtime/Structure.h: Changed from protected pointer to weak pointer.

File:

• trunk/JavaScriptCore/runtime/JSPropertyNameIterator.h (modified) (2 diffs)

trunk/JavaScriptCore/runtime/JSPropertyNameIterator.h

@@ -50 +50 @@
             return Structure::create(prototype, TypeInfo(CompoundType, OverridesMarkChildren), AnonymousSlotCount);
         }
+        
+        virtual ~JSPropertyNameIterator();
 
         virtual bool isPropertyNameIterator() const { return true; }
@@ -82 +84 @@
     };
 
-inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec, PropertyNameArrayData* propertyNameArrayData, size_t numCacheableSlots)
-    : JSCell(exec->globalData().propertyNameIteratorStructure.get())
-    , m_cachedStructure(0)
-    , m_numCacheableSlots(numCacheableSlots)
-    , m_jsStringsSize(propertyNameArrayData->propertyNameVector().size())
-    , m_jsStrings(new JSValue[m_jsStringsSize])
-{
-    PropertyNameArrayData::PropertyNameVector& propertyNameVector = propertyNameArrayData->propertyNameVector();
-    for (size_t i = 0; i < m_jsStringsSize; ++i)
-        m_jsStrings[i] = jsOwnedString(exec, propertyNameVector[i].ustring());
-}
+    inline void Structure::setEnumerationCache(JSPropertyNameIterator* enumerationCache)
+    {
+        ASSERT(!isDictionary());
+        m_enumerationCache = enumerationCache;
+    }
 
-inline void Structure::setEnumerationCache(JSPropertyNameIterator* enumerationCache)
-{
-    ASSERT(!isDictionary());
-    m_enumerationCache = enumerationCache;
-}
+    inline void Structure::clearEnumerationCache(JSPropertyNameIterator* enumerationCache)
+    {
+        m_enumerationCache.clear(enumerationCache);
+    }
+
+    inline JSPropertyNameIterator* Structure::enumerationCache()
+    {
+        return m_enumerationCache.get();
+    }
 
 } // namespace JSC