Changeset 53899 in webkit for trunk/JavaScriptCore/wtf/HashTable.h

Timestamp:

Jan 26, 2010, 9:57:34 PM (15 years ago)

Author:

[email protected]

Message:

Reviewed by Darin Adler.

​https://bugs.webkit.org/show_bug.cgi?id=34150
WebKit needs a mechanism to catch stale HashMap entries

It is very difficult to catch stale pointers that are HashMap keys - since a pointer's hash
is just its value, it is very unlikely that any observable problem is reproducible.

This extends hash table consistency checks to check that pointers are referencing allocated
memory blocks, and makes it possible to invoke the checks explicitly (it is not feasible
to enable CHECK_HASHTABLE_CONSISTENCY by default, because that affects performance too much).

• wtf/HashMap.h: (WTF::::checkConsistency): Call through to HashTable implementation. We can add similar calls to HashSet and HashCountedSet, but I haven't seen hard to debug problems with those yet.

• wtf/HashSet.h: (WTF::::remove): The version of checkTableConsistency that's guarded by CHECK_HASHTABLE_CONSISTENCY is now called internalCheckTableConsistency().

• wtf/HashTable.h: (WTF::HashTable::internalCheckTableConsistency): (WTF::HashTable::internalCheckTableConsistencyExceptSize): (WTF::HashTable::checkTableConsistencyExceptSize): Expose checkTableConsistency() even if CHECK_HASHTABLE_CONSISTENCY is off. (WTF::::add): Updated for checkTableConsistency renaming. (WTF::::addPassingHashCode): Ditto. (WTF::::removeAndInvalidate): Ditto. (WTF::::remove): Ditto. (WTF::::rehash): Ditto. (WTF::::checkTableConsistency): The assertion for !shouldExpand() was not correct - this function returns true for tables with m_table == 0. (WTF::::checkTableConsistencyExceptSize): Call checkValueConsistency for key. Potentially, we could do the same for values.

• wtf/HashTraits.h: (WTF::GenericHashTraits::checkValueConsistency): An empty function that can be overridden to add checks. Currently, the only override is for pointer hashes.

• wtf/RefPtrHashMap.h: (WTF::::remove): Updated for checkTableConsistency renaming.

File:

• trunk/JavaScriptCore/wtf/HashTable.h (modified) (15 diffs)

trunk/JavaScriptCore/wtf/HashTable.h

@@ -31 +31 @@
 
 #define DUMP_HASHTABLE_STATS 0
+// Enables internal WTF consistency checks that are invoked automatically. Non-WTF callers can call checkTableConsistency() even if internal checks are disabled.
 #define CHECK_HASHTABLE_CONSISTENCY 0
 
@@ -341 +342 @@
         template<typename T, typename HashTranslator> ValueType* lookup(const T&);
 
-#if CHECK_HASHTABLE_CONSISTENCY
+#if !ASSERT_DISABLED
         void checkTableConsistency() const;
 #else
         static void checkTableConsistency() { }
+#endif
+#if CHECK_HASHTABLE_CONSISTENCY
+        void internalCheckTableConsistency() const { checkTableConsistency(); }
+        void internalCheckTableConsistencyExceptSize() const { checkTableConsistencyExceptSize(); }
+#else
+        static void internalCheckTableConsistencyExceptSize() { }
+        static void internalCheckTableConsistency() { }
 #endif
 
@@ -384 +392 @@
         const_iterator makeKnownGoodConstIterator(ValueType* pos) const { return const_iterator(this, pos, m_table + m_tableSize, HashItemKnownGood); }
 
-#if CHECK_HASHTABLE_CONSISTENCY
+#if !ASSERT_DISABLED
         void checkTableConsistencyExceptSize() const;
 #else
-        static void checkTableConsistencyExceptSize() { }
+        static void checkTableConsistencyExceptSize() const { }
 #endif
 
@@ -625 +633 @@
             expand();
 
-        checkTableConsistency();
+        internalCheckTableConsistency();
 
         ASSERT(m_table);
@@ -694 +702 @@
         }
         
-        checkTableConsistency();
+        internalCheckTableConsistency();
         
         return std::make_pair(makeKnownGoodIterator(entry), true);
@@ -710 +718 @@
             expand();
 
-        checkTableConsistency();
+        internalCheckTableConsistency();
 
         FullLookupType lookupResult = fullLookupForWriting<T, HashTranslator>(key);
@@ -739 +747 @@
         }
 
-        checkTableConsistency();
+        internalCheckTableConsistency();
 
         return std::make_pair(makeKnownGoodIterator(entry), true);
@@ -806 +814 @@
     {
         invalidateIterators();
-        checkTableConsistency();
+        internalCheckTableConsistency();
         remove(pos);
     }
@@ -824 +832 @@
             shrink();
 
-        checkTableConsistency();
+        internalCheckTableConsistency();
     }
 
@@ -893 +901 @@
     void HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits>::rehash(int newTableSize)
     {
-        checkTableConsistencyExceptSize();
+        internalCheckTableConsistencyExceptSize();
 
         int oldTableSize = m_tableSize;
@@ -915 +923 @@
         deallocateTable(oldTable, oldTableSize);
 
-        checkTableConsistency();
+        internalCheckTableConsistency();
     }
 
@@ -982 +990 @@
     }
 
-#if CHECK_HASHTABLE_CONSISTENCY
+#if !ASSERT_DISABLED
 
     template<typename Key, typename Value, typename Extractor, typename HashFunctions, typename Traits, typename KeyTraits>
@@ -988 +996 @@
     {
         checkTableConsistencyExceptSize();
-        ASSERT(!shouldExpand());
+        ASSERT(!m_table || !shouldExpand());
         ASSERT(!shouldShrink());
     }
@@ -1013 +1021 @@
             ASSERT(entry == it.m_position);
             ++count;
+
+            KeyTraits::checkValueConsistency(it->first);
         }
 
@@ -1022 +1032 @@
     }
 
-#endif // CHECK_HASHTABLE_CONSISTENCY
+#endif // ASSERT_DISABLED
 
 #if CHECK_HASHTABLE_ITERATORS