#ifndef PropertyMapHashTable_h
#define PropertyMapHashTable_h
-#include "UString.h"
+#include "JSExportMacros.h"
+#include "PropertyOffset.h"
+#include "Structure.h"
+#include "WriteBarrier.h"
+#include <wtf/CryptographicallyRandomNumber.h>
+#include <wtf/HashTable.h>
+#include <wtf/MathExtras.h>
+#include <wtf/PassOwnPtr.h>
#include <wtf/Vector.h>
+#include <wtf/text/StringImpl.h>
+
+
+#define DUMP_PROPERTYMAP_STATS 0
+#define DUMP_PROPERTYMAP_COLLISIONS 0
+
+#define PROPERTY_MAP_DELETED_ENTRY_KEY ((StringImpl*)1)
namespace JSC {
- struct PropertyMapEntry {
- UString::Rep* key;
- unsigned offset;
- unsigned attributes;
- JSCell* specificValue;
- unsigned index;
-
- PropertyMapEntry(UString::Rep* key, unsigned attributes, JSCell* specificValue)
- : key(key)
- , offset(0)
- , attributes(attributes)
- , specificValue(specificValue)
- , index(0)
+#if DUMP_PROPERTYMAP_STATS
+
+struct PropertyMapHashTableStats {
+ std::atomic<unsigned> numFinds;
+ std::atomic<unsigned> numCollisions;
+ std::atomic<unsigned> numLookups;
+ std::atomic<unsigned> numLookupProbing;
+ std::atomic<unsigned> numAdds;
+ std::atomic<unsigned> numRemoves;
+ std::atomic<unsigned> numRehashes;
+ std::atomic<unsigned> numReinserts;
+};
+
+JS_EXPORTDATA extern PropertyMapHashTableStats* propertyMapHashTableStats;
+
+#endif
+
+inline bool isPowerOf2(unsigned v)
+{
+ return hasOneBitSet(v);
+}
+
+inline unsigned nextPowerOf2(unsigned v)
+{
+ // Taken from http://www.cs.utk.edu/~vose/c-stuff/bithacks.html
+ // Devised by Sean Anderson, Sepember 14, 2001
+
+ v--;
+ v |= v >> 1;
+ v |= v >> 2;
+ v |= v >> 4;
+ v |= v >> 8;
+ v |= v >> 16;
+ v++;
+
+ return v;
+}
+
+struct PropertyMapEntry {
+ StringImpl* key;
+ PropertyOffset offset;
+ unsigned attributes;
+ WriteBarrier<JSCell> specificValue;
+
+ PropertyMapEntry(VM& vm, JSCell* owner, StringImpl* key, PropertyOffset offset, unsigned attributes, JSCell* specificValue)
+ : key(key)
+ , offset(offset)
+ , attributes(attributes)
+ , specificValue(vm, owner, specificValue, WriteBarrier<JSCell>::MayBeNull)
+ {
+ }
+};
+
+class PropertyTable : public JSCell {
+
+ // This is the implementation for 'iterator' and 'const_iterator',
+ // used for iterating over the table in insertion order.
+ template<typename T>
+ class ordered_iterator {
+ public:
+ ordered_iterator<T>& operator++()
{
+ m_valuePtr = skipDeletedEntries(m_valuePtr + 1);
+ return *this;
}
- PropertyMapEntry(UString::Rep* key, unsigned offset, unsigned attributes, JSCell* specificValue, unsigned index)
- : key(key)
- , offset(offset)
- , attributes(attributes)
- , specificValue(specificValue)
- , index(index)
+ bool operator==(const ordered_iterator<T>& other)
{
+ return m_valuePtr == other.m_valuePtr;
}
- };
- // lastIndexUsed is an ever-increasing index used to identify the order items
- // were inserted into the property map. It's required that getEnumerablePropertyNames
- // return the properties in the order they were added for compatibility with other
- // browsers' JavaScript implementations.
- struct PropertyMapHashTable {
- unsigned sizeMask;
- unsigned size;
- unsigned keyCount;
- unsigned deletedSentinelCount;
- unsigned lastIndexUsed;
- Vector<unsigned>* deletedOffsets;
- unsigned entryIndices[1];
-
- PropertyMapEntry* entries()
+ bool operator!=(const ordered_iterator<T>& other)
{
- // The entries vector comes after the indices vector.
- // The 0th item in the entries vector is not really used; it has to
- // have a 0 in its key to allow the hash table lookup to handle deleted
- // sentinels without any special-case code, but the other fields are unused.
- return reinterpret_cast<PropertyMapEntry*>(&entryIndices[size]);
+ return m_valuePtr != other.m_valuePtr;
}
- static size_t allocationSize(unsigned size)
+ T& operator*()
{
- // We never let a hash table get more than half full,
- // So the number of indices we need is the size of the hash table.
- // But the number of entries is half that (plus one for the deleted sentinel).
- return sizeof(PropertyMapHashTable)
- + (size - 1) * sizeof(unsigned)
- + (1 + size / 2) * sizeof(PropertyMapEntry);
+ return *m_valuePtr;
}
+
+ T* operator->()
+ {
+ return m_valuePtr;
+ }
+
+ ordered_iterator(T* valuePtr)
+ : m_valuePtr(valuePtr)
+ {
+ }
+
+ private:
+ T* m_valuePtr;
};
+public:
+ static const bool needsDestruction = true;
+ static const bool hasImmortalStructure = true;
+ static void destroy(JSCell*);
+
+ DECLARE_EXPORT_INFO;
+
+ static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
+ {
+ return Structure::create(vm, globalObject, prototype, TypeInfo(CompoundType, StructureFlags), info());
+ }
+
+ static void visitChildren(JSCell*, SlotVisitor&);
+
+ typedef StringImpl* KeyType;
+ typedef PropertyMapEntry ValueType;
+
+ // The in order iterator provides overloaded * and -> to access the Value at the current position.
+ typedef ordered_iterator<ValueType> iterator;
+ typedef ordered_iterator<const ValueType> const_iterator;
+
+ // The find_iterator is a pair of a pointer to a Value* an the entry in the index.
+ // If 'find' does not find an entry then iter.first will be 0, and iter.second will
+ // give the point in m_index where an entry should be inserted.
+ typedef std::pair<ValueType*, unsigned> find_iterator;
+
+ // Constructor is passed an initial capacity, a PropertyTable to copy, or both.
+ static PropertyTable* create(VM&, unsigned initialCapacity);
+ static PropertyTable* clone(VM&, const PropertyTable&);
+ static PropertyTable* clone(VM&, unsigned initialCapacity, const PropertyTable&);
+ ~PropertyTable();
+
+ // Ordered iteration methods.
+ iterator begin();
+ iterator end();
+ const_iterator begin() const;
+ const_iterator end() const;
+
+ // Find a value in the table.
+ find_iterator find(const KeyType&);
+ find_iterator findWithString(const KeyType&);
+ ValueType* get(const KeyType&);
+ // Add a value to the table
+ enum EffectOnPropertyOffset { PropertyOffsetMayChange, PropertyOffsetMustNotChange };
+ std::pair<find_iterator, bool> add(const ValueType& entry, PropertyOffset&, EffectOnPropertyOffset);
+ // Remove a value from the table.
+ void remove(const find_iterator& iter);
+ void remove(const KeyType& key);
+
+ // Returns the number of values in the hashtable.
+ unsigned size() const;
+
+ // Checks if there are any values in the hashtable.
+ bool isEmpty() const;
+
+ // Number of slots in the property storage array in use, included deletedOffsets.
+ unsigned propertyStorageSize() const;
+
+ // Used to maintain a list of unused entries in the property storage.
+ void clearDeletedOffsets();
+ bool hasDeletedOffset();
+ PropertyOffset getDeletedOffset();
+ void addDeletedOffset(PropertyOffset);
+
+ PropertyOffset nextOffset(PropertyOffset inlineCapacity);
+
+ // Copy this PropertyTable, ensuring the copy has at least the capacity provided.
+ PropertyTable* copy(VM&, unsigned newCapacity);
+
+#ifndef NDEBUG
+ size_t sizeInMemory();
+ void checkConsistency();
+#endif
+
+protected:
+ static const unsigned StructureFlags = OverridesVisitChildren | StructureIsImmortal;
+
+private:
+ PropertyTable(VM&, unsigned initialCapacity);
+ PropertyTable(VM&, const PropertyTable&);
+ PropertyTable(VM&, unsigned initialCapacity, const PropertyTable&);
+
+ PropertyTable(const PropertyTable&);
+ // Used to insert a value known not to be in the table, and where we know capacity to be available.
+ void reinsert(const ValueType& entry);
+
+ // Rehash the table. Used to grow, or to recover deleted slots.
+ void rehash(unsigned newCapacity);
+
+ // The capacity of the table of values is half of the size of the index.
+ unsigned tableCapacity() const;
+
+ // We keep an extra deleted slot after the array to make iteration work,
+ // and to use for deleted values. Index values into the array are 1-based,
+ // so this is tableCapacity() + 1.
+ // For example, if m_tableSize is 16, then tableCapacity() is 8 - but the
+ // values array is actually 9 long (the 9th used for the deleted value/
+ // iteration guard). The 8 valid entries are numbered 1..8, so the
+ // deleted index is 9 (0 being reserved for empty).
+ unsigned deletedEntryIndex() const;
+
+ // Used in iterator creation/progression.
+ template<typename T>
+ static T* skipDeletedEntries(T* valuePtr);
+
+ // The table of values lies after the hash index.
+ ValueType* table();
+ const ValueType* table() const;
+
+ // total number of used entries in the values array - by either valid entries, or deleted ones.
+ unsigned usedCount() const;
+
+ // The size in bytes of data needed for by the table.
+ size_t dataSize();
+
+ // Calculates the appropriate table size (rounds up to a power of two).
+ static unsigned sizeForCapacity(unsigned capacity);
+
+ // Check if capacity is available.
+ bool canInsert();
+
+ unsigned m_indexSize;
+ unsigned m_indexMask;
+ unsigned* m_index;
+ unsigned m_keyCount;
+ unsigned m_deletedCount;
+ OwnPtr< Vector<PropertyOffset>> m_deletedOffsets;
+
+ static const unsigned MinimumTableSize = 16;
+ static const unsigned EmptyEntryIndex = 0;
+};
+
+inline PropertyTable::iterator PropertyTable::begin()
+{
+ return iterator(skipDeletedEntries(table()));
+}
+
+inline PropertyTable::iterator PropertyTable::end()
+{
+ return iterator(table() + usedCount());
+}
+
+inline PropertyTable::const_iterator PropertyTable::begin() const
+{
+ return const_iterator(skipDeletedEntries(table()));
+}
+
+inline PropertyTable::const_iterator PropertyTable::end() const
+{
+ return const_iterator(table() + usedCount());
+}
+
+inline PropertyTable::find_iterator PropertyTable::find(const KeyType& key)
+{
+ ASSERT(key);
+ ASSERT(key->isAtomic() || key->isEmptyUnique());
+ unsigned hash = key->existingHash();
+ unsigned step = 0;
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numFinds;
+#endif
+
+ while (true) {
+ unsigned entryIndex = m_index[hash & m_indexMask];
+ if (entryIndex == EmptyEntryIndex)
+ return std::make_pair((ValueType*)0, hash & m_indexMask);
+ if (key == table()[entryIndex - 1].key)
+ return std::make_pair(&table()[entryIndex - 1], hash & m_indexMask);
+
+ if (!step)
+ step = WTF::doubleHash(key->existingHash()) | 1;
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numCollisions;
+#endif
+
+#if DUMP_PROPERTYMAP_COLLISIONS
+ dataLog("PropertyTable collision for ", key, " (", hash, ") with step ", step, "\n");
+ dataLog("Collided with ", table()[entryIndex - 1].key, "(", table()[entryIndex - 1].key->existingHash(), ")\n");
+#endif
+
+ hash += step;
+ }
+}
+
+inline PropertyTable::ValueType* PropertyTable::get(const KeyType& key)
+{
+ ASSERT(key);
+ ASSERT(key->isAtomic() || key->isEmptyUnique());
+
+ if (!m_keyCount)
+ return nullptr;
+
+ unsigned hash = key->existingHash();
+ unsigned step = 0;
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numLookups;
+#endif
+
+ while (true) {
+ unsigned entryIndex = m_index[hash & m_indexMask];
+ if (entryIndex == EmptyEntryIndex)
+ return nullptr;
+ if (key == table()[entryIndex - 1].key)
+ return &table()[entryIndex - 1];
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numLookupProbing;
+#endif
+
+ if (!step)
+ step = WTF::doubleHash(key->existingHash()) | 1;
+ hash += step;
+ }
+}
+
+inline PropertyTable::find_iterator PropertyTable::findWithString(const KeyType& key)
+{
+ ASSERT(key);
+ ASSERT(!key->isAtomic() && !key->hasHash());
+ unsigned hash = key->hash();
+ unsigned step = 0;
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numLookups;
+#endif
+
+ while (true) {
+ unsigned entryIndex = m_index[hash & m_indexMask];
+ if (entryIndex == EmptyEntryIndex)
+ return std::make_pair((ValueType*)0, hash & m_indexMask);
+ const KeyType& keyInMap = table()[entryIndex - 1].key;
+ if (equal(key, keyInMap) && keyInMap->isAtomic())
+ return std::make_pair(&table()[entryIndex - 1], hash & m_indexMask);
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numLookupProbing;
+#endif
+
+ if (!step)
+ step = WTF::doubleHash(key->existingHash()) | 1;
+ hash += step;
+ }
+}
+
+inline std::pair<PropertyTable::find_iterator, bool> PropertyTable::add(const ValueType& entry, PropertyOffset& offset, EffectOnPropertyOffset offsetEffect)
+{
+ // Look for a value with a matching key already in the array.
+ find_iterator iter = find(entry.key);
+ if (iter.first) {
+ RELEASE_ASSERT(iter.first->offset <= offset);
+ return std::make_pair(iter, false);
+ }
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numAdds;
+#endif
+
+ // Ref the key
+ entry.key->ref();
+
+ // ensure capacity is available.
+ if (!canInsert()) {
+ rehash(m_keyCount + 1);
+ iter = find(entry.key);
+ ASSERT(!iter.first);
+ }
+
+ // Allocate a slot in the hashtable, and set the index to reference this.
+ unsigned entryIndex = usedCount() + 1;
+ m_index[iter.second] = entryIndex;
+ iter.first = &table()[entryIndex - 1];
+ *iter.first = entry;
+
+ ++m_keyCount;
+
+ if (offsetEffect == PropertyOffsetMayChange)
+ offset = std::max(offset, entry.offset);
+ else
+ RELEASE_ASSERT(offset >= entry.offset);
+
+ return std::make_pair(iter, true);
+}
+
+inline void PropertyTable::remove(const find_iterator& iter)
+{
+ // Removing a key that doesn't exist does nothing!
+ if (!iter.first)
+ return;
+
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numRemoves;
+#endif
+
+ // Replace this one element with the deleted sentinel. Also clear out
+ // the entry so we can iterate all the entries as needed.
+ m_index[iter.second] = deletedEntryIndex();
+ iter.first->key->deref();
+ iter.first->key = PROPERTY_MAP_DELETED_ENTRY_KEY;
+
+ ASSERT(m_keyCount >= 1);
+ --m_keyCount;
+ ++m_deletedCount;
+
+ if (m_deletedCount * 4 >= m_indexSize)
+ rehash(m_keyCount);
+}
+
+inline void PropertyTable::remove(const KeyType& key)
+{
+ remove(find(key));
+}
+
+// returns the number of values in the hashtable.
+inline unsigned PropertyTable::size() const
+{
+ return m_keyCount;
+}
+
+inline bool PropertyTable::isEmpty() const
+{
+ return !m_keyCount;
+}
+
+inline unsigned PropertyTable::propertyStorageSize() const
+{
+ return size() + (m_deletedOffsets ? m_deletedOffsets->size() : 0);
+}
+
+inline void PropertyTable::clearDeletedOffsets()
+{
+ m_deletedOffsets.clear();
+}
+
+inline bool PropertyTable::hasDeletedOffset()
+{
+ return m_deletedOffsets && !m_deletedOffsets->isEmpty();
+}
+
+inline PropertyOffset PropertyTable::getDeletedOffset()
+{
+ PropertyOffset offset = m_deletedOffsets->last();
+ m_deletedOffsets->removeLast();
+ return offset;
+}
+
+inline void PropertyTable::addDeletedOffset(PropertyOffset offset)
+{
+ if (!m_deletedOffsets)
+ m_deletedOffsets = adoptPtr(new Vector<PropertyOffset>);
+ m_deletedOffsets->append(offset);
+}
+
+inline PropertyOffset PropertyTable::nextOffset(PropertyOffset inlineCapacity)
+{
+ if (hasDeletedOffset())
+ return getDeletedOffset();
+
+ return offsetForPropertyNumber(size(), inlineCapacity);
+}
+
+inline PropertyTable* PropertyTable::copy(VM& vm, unsigned newCapacity)
+{
+ ASSERT(newCapacity >= m_keyCount);
+
+ // Fast case; if the new table will be the same m_indexSize as this one, we can memcpy it,
+ // save rehashing all keys.
+ if (sizeForCapacity(newCapacity) == m_indexSize)
+ return PropertyTable::clone(vm, *this);
+ return PropertyTable::clone(vm, newCapacity, *this);
+}
+
+#ifndef NDEBUG
+inline size_t PropertyTable::sizeInMemory()
+{
+ size_t result = sizeof(PropertyTable) + dataSize();
+ if (m_deletedOffsets)
+ result += (m_deletedOffsets->capacity() * sizeof(PropertyOffset));
+ return result;
+}
+#endif
+
+inline void PropertyTable::reinsert(const ValueType& entry)
+{
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numReinserts;
+#endif
+
+ // Used to insert a value known not to be in the table, and where
+ // we know capacity to be available.
+ ASSERT(canInsert());
+ find_iterator iter = find(entry.key);
+ ASSERT(!iter.first);
+
+ unsigned entryIndex = usedCount() + 1;
+ m_index[iter.second] = entryIndex;
+ table()[entryIndex - 1] = entry;
+
+ ++m_keyCount;
+}
+
+inline void PropertyTable::rehash(unsigned newCapacity)
+{
+#if DUMP_PROPERTYMAP_STATS
+ ++propertyMapHashTableStats->numRehashes;
+#endif
+
+ unsigned* oldEntryIndices = m_index;
+ iterator iter = this->begin();
+ iterator end = this->end();
+
+ m_indexSize = sizeForCapacity(newCapacity);
+ m_indexMask = m_indexSize - 1;
+ m_keyCount = 0;
+ m_deletedCount = 0;
+ m_index = static_cast<unsigned*>(fastZeroedMalloc(dataSize()));
+
+ for (; iter != end; ++iter) {
+ ASSERT(canInsert());
+ reinsert(*iter);
+ }
+
+ fastFree(oldEntryIndices);
+}
+
+inline unsigned PropertyTable::tableCapacity() const { return m_indexSize >> 1; }
+
+inline unsigned PropertyTable::deletedEntryIndex() const { return tableCapacity() + 1; }
+
+template<typename T>
+inline T* PropertyTable::skipDeletedEntries(T* valuePtr)
+{
+ while (valuePtr->key == PROPERTY_MAP_DELETED_ENTRY_KEY)
+ ++valuePtr;
+ return valuePtr;
+}
+
+inline PropertyTable::ValueType* PropertyTable::table()
+{
+ // The table of values lies after the hash index.
+ return reinterpret_cast<ValueType*>(m_index + m_indexSize);
+}
+
+inline const PropertyTable::ValueType* PropertyTable::table() const
+{
+ // The table of values lies after the hash index.
+ return reinterpret_cast<const ValueType*>(m_index + m_indexSize);
+}
+
+inline unsigned PropertyTable::usedCount() const
+{
+ // Total number of used entries in the values array - by either valid entries, or deleted ones.
+ return m_keyCount + m_deletedCount;
+}
+
+inline size_t PropertyTable::dataSize()
+{
+ // The size in bytes of data needed for by the table.
+ return m_indexSize * sizeof(unsigned) + ((tableCapacity()) + 1) * sizeof(ValueType);
+}
+
+inline unsigned PropertyTable::sizeForCapacity(unsigned capacity)
+{
+ if (capacity < MinimumTableSize / 2)
+ return MinimumTableSize;
+ return nextPowerOf2(capacity + 1) * 2;
+}
+
+inline bool PropertyTable::canInsert()
+{
+ return usedCount() < tableCapacity();
+}
+
} // namespace JSC
#endif // PropertyMapHashTable_h
projects / apple / javascriptcore.git / blobdiff