Add more oilpan collections support

Source/heap/Heap.h

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 703 matching lines @@
     virtual void makeConsistentForGC();
     virtual bool isConsistentForGC();
 
     ThreadState* threadState() { return m_threadState; }
     HeapStats& stats() { return m_threadState->stats(); }
     HeapContainsCache* heapContainsCache() { return m_threadState->heapContainsCache(); }
 
     inline Address allocate(size_t, const GCInfo*);
     void addToFreeList(Address, size_t);
     void addPageToPool(HeapPage<Header>*);
-    inline size_t roundedAllocationSize(size_t size)
+    inline static size_t roundedAllocationSize(size_t size)
     {
         return allocationSizeFromSize(size) - sizeof(Header);
     }
 
 private:
     // Once pages have been used for one thread heap they will never
     // be reused for another thread heap. Instead of unmapping, we add
     // the pages to a pool of pages to be reused later by this thread
     // heap. This is done as a security feature to avoid type
     // confusion. The heap is type segregated by having separate
@@ skipping 10 matching lines @@
 
         PageMemory* storage() { return m_storage; }
         PagePoolEntry* next() { return m_next; }
 
     private:
         PageMemory* m_storage;
         PagePoolEntry* m_next;
     };
 
     HEAP_EXPORT Address outOfLineAllocate(size_t, const GCInfo*);
-    size_t allocationSizeFromSize(size_t);
+    static size_t allocationSizeFromSize(size_t);
     void addPageToHeap(const GCInfo*);
     HEAP_EXPORT Address allocateLargeObject(size_t, const GCInfo*);
     Address currentAllocationPoint() const { return m_currentAllocationPoint; }
     size_t remainingAllocationSize() const { return m_remainingAllocationSize; }
     bool ownsNonEmptyAllocationArea() const { return currentAllocationPoint() && remainingAllocationSize(); }
     void setAllocationPoint(Address point, size_t size)
     {
         ASSERT(!point || heapPageFromAddress(point));
         ASSERT(size <= HeapPage<Header>::payloadSize());
         m_currentAllocationPoint = point;
@@ skipping 388 matching lines @@
     memcpy(address, previous, copySize);
     return address;
 }
 
 class HeapAllocatorQuantizer {
 public:
     template<typename T>
     static size_t quantizedSize(size_t count)
     {
         RELEASE_ASSERT(count <= kMaxUnquantizedAllocation / sizeof(T));
-        return typename HeapTrait<T>::HeapType::roundedAllocationSize(count * sizeof(T));
+        return HeapTrait<T>::HeapType::roundedAllocationSize(count * sizeof(T));
     }
     static const size_t kMaxUnquantizedAllocation = maxHeapObjectSize;
 };
 
 class HeapAllocator {
 public:
     typedef HeapAllocatorQuantizer Quantizer;
     typedef WebCore::Visitor Visitor;
     static const bool isGarbageCollected = true;
 
@@ skipping 19 matching lines @@
     {
         ASSERT_NOT_REACHED();
         return nullptr;
     }
 
     static void deleteArray(void* ptr)
     {
         ASSERT_NOT_REACHED();
     }
 
     static void markUsingGCInfo(Visitor* visitor, const void* buffer)

[haraken, 2014/01/15 04:48:35]

How about just calling this method "mark"? Or probably "traceUsingGCInfo"? (I
don't fully understand whether this method should be called "mark" or "trace".)

     {
         visitor->mark(buffer, FinalizedHeapObjectHeader::fromPayload(buffer)->traceCallback());
     }
 
     static void markNoTracing(Visitor* visitor, const void* t)

[haraken, 2014/01/15 04:48:35]

markNoTracing => markWithoutTracing ?

[Erik Corry, 2014/01/15 09:27:32]

I think we have a little too much naming churn.  You approved the old name last
week, let's just leave it as it is.

     {
         visitor->mark(t);
     }
 
     template<typename T, typename Traits>
-    static void mark(Visitor* visitor, T& t)
+    static void trace(Visitor* visitor, T& t)
     {
         CollectionBackingTraceTrait<Traits::needsTracing, Traits::isWeak, false, T, Traits>::mark(visitor, t);
     }
 
     template<typename T>
     static bool hasDeadMember(Visitor*, const T&)
     {
         return false;
     }
 
@@ skipping 55 matching lines @@
     {
         return *(other);
     }
 
 private:
     template<typename T, size_t u, typename V> friend class WTF::Vector;
     template<typename T, typename U, typename V, typename W> friend class WTF::HashSet;
     template<typename T, typename U, typename V, typename W, typename X, typename Y> friend class WTF::HashMap;
 };
 
+// FIXME: These should just be template aliases:
+//
+// template<typename T, size_t inlineCapacity = 0>
+// using HeapVector = Vector<T, inlineCapacity, HeapAllocator>;
+//
+// as soon as all the compilers we care about support that.
+// MSVC supports it only in MSVC 2013.
+template<
+    typename KeyArg,
+    typename MappedArg,
+    typename HashArg = typename DefaultHash<KeyArg>::Hash,
+    typename KeyTraitsArg = HashTraits<KeyArg>,
+    typename MappedTraitsArg = HashTraits<MappedArg> >
+class HeapHashMap : public HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg, HeapAllocator> { };
+
+template<
+    typename ValueArg,
+    typename HashArg = typename DefaultHash<ValueArg>::Hash,
+    typename TraitsArg = HashTraits<ValueArg> >
+class HeapHashSet : public HashSet<ValueArg, HashArg, TraitsArg, HeapAllocator> { };
+
+template<typename T, size_t inlineCapacity = 0>
+class HeapVector : public Vector<T, inlineCapacity, HeapAllocator> {
+public:
+    HeapVector() { }
+
+    explicit HeapVector(size_t size) : Vector<T, inlineCapacity, HeapAllocator>(size)
+    {
+    }
+
+    template<size_t otherCapacity>
+    HeapVector(const HeapVector<T, otherCapacity>& other)
+        : Vector<T, inlineCapacity, HeapAllocator>(other)
+    {
+    }
+
+    template<typename U>
+    void append(const U& other)
+    {
+        Vector<T, inlineCapacity, HeapAllocator>::append(other);
+    }
+
+    template<typename U, size_t otherCapacity>
+    void append(const HeapVector<U, otherCapacity>& other)
+    {
+        const Vector<U, otherCapacity, HeapAllocator>& otherVector = other;
+        Vector<T, inlineCapacity, HeapAllocator>::append(otherVector);
+    }
+};
+
+template<typename SetType>
+inline void clearWeakSet(Visitor* visitor, SetType& set)
+{
+    typedef Vector<typename SetType::ValueType, 10> DeadSet;
+    DeadSet dead;
+
+    for (typename SetType::iterator it = set.begin(), end = set.end(); it != end; ++it) {
+        if (!ObjectAliveTrait<typename SetType::ValueType>::isAlive(visitor, *it))
+            dead.append(*it);
+    }
+
+    for (typename DeadSet::iterator it = dead.begin(), end = dead.end(); it != end; ++it) {
+        set.remove(*it);
+    }
+}
+
+template<typename SetType>
+inline void clearWeakCountedSet(Visitor* visitor, SetType& set)
+{
+    typedef Vector<typename SetType::ValueType, 10> DeadSet;
+    DeadSet dead;
+
+    for (typename SetType::iterator it = set.begin(), end = set.end(); it != end; ++it) {
+        if (!ObjectAliveTrait<typename SetType::ValueType>::isAlive(visitor, it->key))
+            dead.append(it->key);
+    }
+
+    for (typename DeadSet::iterator it = dead.begin(), end = dead.end(); it != end; ++it) {
+        set.removeAll(*it);
+    }
+}
+
+template<typename MapType>
+inline void clearWeakMap(Visitor* visitor, MapType& map)
+{
+    typedef Vector<typename MapType::KeyType, 10> DeadSet;
+    DeadSet dead;
+
+    for (typename MapType::iterator it = map.begin(), end = map.end(); it != end; ++it) {
+        if (!ObjectAliveTrait<typename MapType::KeyType>::isAlive(visitor, it->key))
+            dead.append(it->key);
+    }
+
+    for (typename DeadSet::iterator it = dead.begin(), end = dead.end(); it != end; ++it) {
+        map.remove(*it);
+    }
+}
+
+template<typename MapType, typename T>
+inline void clearWeakMap(Visitor* visitor, MapType& map, void (*callback)(T, const typename MapType::KeyType&, typename MapType::MappedType), T data)

[haraken, 2014/01/15 04:48:35]

Can we make |callback| and |data| default parameters, and remove 'inline void
clearWeakMap(Visitor* visitor, MapType& map)'?

[Erik Corry, 2014/01/15 09:27:32]

Actually these routines are there for handling off-heap weak collections. They
are a bit dangerous because if you have a GC while you are iterating over them,
the current position of the iterator may be invalidated. Therefore we decided to
omit support for off-heap weak collections and see if we can just use on-heap
weak collections, which are safe for GC during iteration.

So I removed this code for now.

+{
+    typedef Vector<typename MapType::KeyType, 10> DeadSet;
+    DeadSet dead;
+
+    for (typename MapType::iterator it = map.begin(), end = map.end(); it != end; ++it) {
+        if (!ObjectAliveTrait<typename MapType::KeyType>::isAlive(visitor, it->key)) {
+            dead.append(it->key);
+            callback(data, it->key, it->value);
+        }
+    }
+
+    for (typename DeadSet::iterator it = dead.begin(), end = dead.end(); it != end; ++it) {
+        map.remove(*it);
+    }
+}
+
+template<typename MapType>
+inline void clearWeakMapValues(Visitor* visitor, MapType& map)

[haraken, 2014/01/15 04:48:35]

When is this method used? It looks a bit strange to me that we want to remove
keys when corresponding values are not alive.

[Erik Corry, 2014/01/15 09:27:32]

This code is gone now, but we have the same semantics for on-heap weak maps.  If
you have a

HeapHashMap<Foo, WeakMember<Bar> >

Then if the bar is collected, the entire map entry is removed, rather than just
leaving a mapping from a foo to null.  I think this is actually the best
semantics, since it allows you to GC the foo (in the next GC) and there's rarely
any benefit to having a mapping to something that is gone.

+{
+    typedef Vector<typename MapType::KeyType, 10> DeadSet;
+    DeadSet dead;
+
+    for (typename MapType::iterator it = map.begin(), end = map.end(); it != end; ++it) {
+        if (!ObjectAliveTrait<typename MapType::MappedType>::isAlive(visitor, it->value))
+            dead.append(it->key);
+    }
+
+    for (typename DeadSet::iterator it = dead.begin(), end = dead.end(); it != end; ++it) {
+        map.remove(*it);
+    }
+}
+
+template<typename Key, typename Value>
+struct ThreadingTrait<HeapHashMap<Key, Value> > : public ThreadingTrait<HashMap<Key, Value, HeapAllocator> > { };
+template<typename Value>
+struct ThreadingTrait<HeapHashSet<Value> > : public ThreadingTrait<HashSet<Value, HeapAllocator> > { };
+template<typename T, size_t inlineCapacity>
+struct ThreadingTrait<HeapVector<T, inlineCapacity> > : public ThreadingTrait<Vector<T, inlineCapacity, HeapAllocator> > { };
+
 // The standard implementation of GCInfoTrait<T>::get() just returns a static
 // from the class T, but we can't do that for HashMap, HashSet and Vector
 // because they are in WTF and know nothing of GCInfos. Instead we have a
 // specialization of GCInfoTrait for these three classes here.
 
 template<typename Key, typename Value, typename T, typename U, typename V>
 struct GCInfoTrait<HashMap<Key, Value, T, U, V, HeapAllocator> > {
     static const GCInfo* get() { return &info; }
     static const GCInfo info;
 };
@@ skipping 254 matching lines @@
             visitor->mark(backing, 0);
     }
     static void checkTypeMarker(Visitor* visitor, const Backing* backing)
     {
 #ifndef NDEBUG
         visitor->checkTypeMarker(const_cast<Backing*>(backing), getTypeMarker<Backing>());
 #endif
     }
 };
 
+template<typename T, typename U, typename V, typename W, typename X>
+struct GCInfoTrait<HeapHashMap<T, U, V, W, X> > : public GCInfoTrait<HashMap<T, U, V, W, X, HeapAllocator> > { };
+template<typename T, typename U, typename V>
+struct GCInfoTrait<HeapHashSet<T, U, V> > : public GCInfoTrait<HashSet<T, U, V, HeapAllocator> > { };
+template<typename T, size_t inlineCapacity>
+struct GCInfoTrait<HeapVector<T, inlineCapacity> > : public GCInfoTrait<Vector<T, inlineCapacity, HeapAllocator> > { };
+
 template<typename T>
 struct IfWeakMember;
 
 template<typename T>
 struct IfWeakMember {
     template<typename U>
     static bool isDead(Visitor*, const U&) { return false; }
 };
 
 template<typename T>
 struct IfWeakMember<WeakMember<T> > {
     static bool isDead(Visitor* visitor, const WeakMember<T>& t) { return !visitor->isAlive(t.raw()); }
 };
 
-template<typename K, typename V, typename HashFunctions, typename KeyTraits, typename ValueTraits>
-void processWeakOffHeapHashMap(Visitor* visitor, void* self)
-{
-    typedef HashMap<K, V, WTF::DefaultAllocator, HashFunctions, KeyTraits, ValueTraits> Map;
-    Map* map = reinterpret_cast<Map*>(self);
-    // Collect up keys here because we can't modify a hash map while iterating
-    // over it.
-    Vector<K> deletionKeys;
-    ASSERT(KeyTraits::isWeak || ValueTraits::isWeak);
-    typedef typename Map::iterator Iterator;
-    Iterator endIterator(map->end());
-    for (Iterator it = map->begin(); it != endIterator; ++it) {
-        if (IfWeakMember<K>::isDead(visitor, it->key))
-            deletionKeys.append(it->key);
-        else if (IfWeakMember<V>::isDead(visitor, it->value))
-            deletionKeys.append(it->key);
-    }
-    size_t size = deletionKeys.size();
-    if (size == map->size()) {
-        map->clear();
-        return;
-    }
-    for (size_t i = 0; i < size; i++)
-        map->remove(deletionKeys[i]);
-}
-
-template<typename T, typename HashFunctions, typename Traits>
-void processWeakOffHeapHashSet(Visitor* visitor, void* self)
-{
-    typedef HashSet<T, WTF::DefaultAllocator, HashFunctions, Traits> Set;
-    Set* set = reinterpret_cast<Set*>(self);
-    ASSERT(Traits::isWeak);
-    // Collect up keys here because we can't modify a hash set while iterating
-    // over it.
-    Vector<T> deletionKeys;
-    typedef typename Set::iterator Iterator;
-    Iterator endIterator(set->end());
-    for (Iterator it = set->begin(); it != endIterator; ++it) {
-        if (IfWeakMember<T>::isDead(visitor, *it))
-            deletionKeys.append(*it);
-    }
-    size_t size = deletionKeys.size();
-    if (size == set->size()) {
-        set->clear();
-        return;
-    }
-    for (size_t i = 0; i < size; i++)
-        set->remove(deletionKeys[i]);
-}
-
 #if COMPILER(CLANG)
 // Clang does not export the symbols that we have explicitly asked it
 // to export. This forces it to export all the methods from ThreadHeap.
 template<> void ThreadHeap<FinalizedHeapObjectHeader>::addPageToHeap(const GCInfo*);
 template<> void ThreadHeap<HeapObjectHeader>::addPageToHeap(const GCInfo*);
 extern template class HEAP_EXPORT ThreadHeap<FinalizedHeapObjectHeader>;
 extern template class HEAP_EXPORT ThreadHeap<HeapObjectHeader>;
 #endif
 
 }
 
 #endif // Heap_h