Changeset 53957 in webkit for trunk/JavaScriptCore/wtf/RefPtrHashMap.h

Timestamp:

Jan 27, 2010, 3:41:50 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/RefPtrHashMap.h (modified) (1 diff)

trunk/JavaScriptCore/wtf/RefPtrHashMap.h

@@ -286 +286 @@
         if (it.m_impl == m_impl.end())
             return;
-        m_impl.checkTableConsistency();
+        m_impl.internalCheckTableConsistency();
         m_impl.removeWithoutEntryConsistencyCheck(it.m_impl);
     }