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https://github.com/libretro/scummvm.git
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53d0fe22d9
When erasing and inserting many items this caused the hashmap capacity to grow more than it should which resulted in performances issues (and possibly memory issues as well). The issue was reported on IRC today with the wintermute engine.
638 lines
18 KiB
C++
638 lines
18 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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// The hash map (associative array) implementation in this file is
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// based on the PyDict implementation of CPython.
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#ifndef COMMON_HASHMAP_H
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#define COMMON_HASHMAP_H
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/**
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* @def DEBUG_HASH_COLLISIONS
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* Enable the following #define if you want to check how many collisions the
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* code produces (many collisions indicate either a bad hash function, or a
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* hash table that is too small).
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*/
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//#define DEBUG_HASH_COLLISIONS
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/**
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* @def USE_HASHMAP_MEMORY_POOL
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* Enable the following define to let HashMaps use a memory pool for the
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nodes they contain. * This increases memory usage, but also can improve
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speed quite a bit.
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*/
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#define USE_HASHMAP_MEMORY_POOL
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#include "common/func.h"
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#ifdef DEBUG_HASH_COLLISIONS
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#include "common/debug.h"
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#endif
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#ifdef USE_HASHMAP_MEMORY_POOL
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#include "common/memorypool.h"
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#endif
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namespace Common {
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// The sgi IRIX MIPSpro Compiler has difficulties with nested templates.
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// This and the other __sgi conditionals below work around these problems.
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// The Intel C++ Compiler suffers from the same problems.
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#if (defined(__sgi) && !defined(__GNUC__)) || defined(__INTEL_COMPILER)
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template<class T> class IteratorImpl;
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#endif
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/**
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* HashMap<Key,Val> maps objects of type Key to objects of type Val.
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* For each used Key type, we need an "size_type hashit(Key,size_type)" function
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* that computes a hash for the given Key object and returns it as an
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* an integer from 0 to hashsize-1, and also an "equality functor".
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* that returns true if if its two arguments are to be considered
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* equal. Also, we assume that "=" works on Val objects for assignment.
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*
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* If aa is an HashMap<Key,Val>, then space is allocated each time aa[key] is
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* referenced, for a new key. If the object is const, then an assertion is
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* triggered instead. Hence if you are not sure whether a key is contained in
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* the map, use contains() first to check for its presence.
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*/
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template<class Key, class Val, class HashFunc = Hash<Key>, class EqualFunc = EqualTo<Key> >
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class HashMap {
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public:
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typedef uint size_type;
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private:
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typedef HashMap<Key, Val, HashFunc, EqualFunc> HM_t;
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struct Node {
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const Key _key;
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Val _value;
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explicit Node(const Key &key) : _key(key), _value() {}
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Node() : _key(), _value() {}
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};
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enum {
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HASHMAP_PERTURB_SHIFT = 5,
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HASHMAP_MIN_CAPACITY = 16,
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// The quotient of the next two constants controls how much the
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// internal storage of the hashmap may fill up before being
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// increased automatically.
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// Note: the quotient of these two must be between and different
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// from 0 and 1.
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HASHMAP_LOADFACTOR_NUMERATOR = 2,
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HASHMAP_LOADFACTOR_DENOMINATOR = 3,
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HASHMAP_MEMORYPOOL_SIZE = HASHMAP_MIN_CAPACITY * HASHMAP_LOADFACTOR_NUMERATOR / HASHMAP_LOADFACTOR_DENOMINATOR
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};
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#ifdef USE_HASHMAP_MEMORY_POOL
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ObjectPool<Node, HASHMAP_MEMORYPOOL_SIZE> _nodePool;
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#endif
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Node **_storage; ///< hashtable of size arrsize.
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size_type _mask; ///< Capacity of the HashMap minus one; must be a power of two of minus one
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size_type _size;
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size_type _deleted; ///< Number of deleted elements (_dummyNodes)
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HashFunc _hash;
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EqualFunc _equal;
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/** Default value, returned by the const getVal. */
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const Val _defaultVal;
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/** Dummy node, used as marker for erased objects. */
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#define HASHMAP_DUMMY_NODE ((Node *)1)
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#ifdef DEBUG_HASH_COLLISIONS
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mutable int _collisions, _lookups, _dummyHits;
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#endif
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Node *allocNode(const Key &key) {
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#ifdef USE_HASHMAP_MEMORY_POOL
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return new (_nodePool) Node(key);
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#else
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return new Node(key);
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#endif
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}
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void freeNode(Node *node) {
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if (node && node != HASHMAP_DUMMY_NODE)
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#ifdef USE_HASHMAP_MEMORY_POOL
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_nodePool.deleteChunk(node);
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#else
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delete node;
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#endif
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}
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void assign(const HM_t &map);
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size_type lookup(const Key &key) const;
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size_type lookupAndCreateIfMissing(const Key &key);
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void expandStorage(size_type newCapacity);
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#if !defined(__sgi) || defined(__GNUC__)
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template<class T> friend class IteratorImpl;
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#endif
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/**
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* Simple HashMap iterator implementation.
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*/
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template<class NodeType>
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class IteratorImpl {
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friend class HashMap;
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#if (defined(__sgi) && !defined(__GNUC__)) || defined(__INTEL_COMPILER)
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template<class T> friend class Common::IteratorImpl;
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#else
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template<class T> friend class IteratorImpl;
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#endif
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protected:
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typedef const HashMap hashmap_t;
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size_type _idx;
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hashmap_t *_hashmap;
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protected:
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IteratorImpl(size_type idx, hashmap_t *hashmap) : _idx(idx), _hashmap(hashmap) {}
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NodeType *deref() const {
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assert(_hashmap != nullptr);
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assert(_idx <= _hashmap->_mask);
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Node *node = _hashmap->_storage[_idx];
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assert(node != nullptr);
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assert(node != HASHMAP_DUMMY_NODE);
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return node;
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}
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public:
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IteratorImpl() : _idx(0), _hashmap(nullptr) {}
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template<class T>
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IteratorImpl(const IteratorImpl<T> &c) : _idx(c._idx), _hashmap(c._hashmap) {}
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NodeType &operator*() const { return *deref(); }
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NodeType *operator->() const { return deref(); }
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bool operator==(const IteratorImpl &iter) const { return _idx == iter._idx && _hashmap == iter._hashmap; }
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bool operator!=(const IteratorImpl &iter) const { return !(*this == iter); }
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IteratorImpl &operator++() {
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assert(_hashmap);
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do {
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_idx++;
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} while (_idx <= _hashmap->_mask && (_hashmap->_storage[_idx] == nullptr || _hashmap->_storage[_idx] == HASHMAP_DUMMY_NODE));
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if (_idx > _hashmap->_mask)
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_idx = (size_type)-1;
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return *this;
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}
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IteratorImpl operator++(int) {
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IteratorImpl old = *this;
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operator ++();
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return old;
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}
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};
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public:
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typedef IteratorImpl<Node> iterator;
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typedef IteratorImpl<const Node> const_iterator;
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HashMap();
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HashMap(const HM_t &map);
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~HashMap();
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HM_t &operator=(const HM_t &map) {
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if (this == &map)
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return *this;
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// Remove the previous content and ...
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clear();
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delete[] _storage;
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// ... copy the new stuff.
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assign(map);
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return *this;
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}
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bool contains(const Key &key) const;
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Val &operator[](const Key &key);
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const Val &operator[](const Key &key) const;
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Val &getVal(const Key &key);
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const Val &getVal(const Key &key) const;
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const Val &getVal(const Key &key, const Val &defaultVal) const;
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void setVal(const Key &key, const Val &val);
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void clear(bool shrinkArray = 0);
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void erase(iterator entry);
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void erase(const Key &key);
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size_type size() const { return _size; }
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iterator begin() {
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// Find and return the first non-empty entry
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for (size_type ctr = 0; ctr <= _mask; ++ctr) {
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if (_storage[ctr] && _storage[ctr] != HASHMAP_DUMMY_NODE)
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return iterator(ctr, this);
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}
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return end();
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}
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iterator end() {
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return iterator((size_type)-1, this);
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}
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const_iterator begin() const {
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// Find and return the first non-empty entry
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for (size_type ctr = 0; ctr <= _mask; ++ctr) {
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if (_storage[ctr] && _storage[ctr] != HASHMAP_DUMMY_NODE)
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return const_iterator(ctr, this);
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}
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return end();
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}
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const_iterator end() const {
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return const_iterator((size_type)-1, this);
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}
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iterator find(const Key &key) {
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size_type ctr = lookup(key);
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if (_storage[ctr])
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return iterator(ctr, this);
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return end();
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}
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const_iterator find(const Key &key) const {
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size_type ctr = lookup(key);
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if (_storage[ctr])
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return const_iterator(ctr, this);
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return end();
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}
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// TODO: insert() method?
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bool empty() const {
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return (_size == 0);
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}
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};
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//-------------------------------------------------------
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// HashMap functions
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/**
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* Base constructor, creates an empty hashmap.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::HashMap()
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//
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// We have to skip _defaultVal() on PS2 to avoid gcc 3.2.2 ICE
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//
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#ifdef __PLAYSTATION2__
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{
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#else
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: _defaultVal() {
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#endif
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_mask = HASHMAP_MIN_CAPACITY - 1;
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_storage = new Node *[HASHMAP_MIN_CAPACITY];
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assert(_storage != nullptr);
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memset(_storage, 0, HASHMAP_MIN_CAPACITY * sizeof(Node *));
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_size = 0;
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_deleted = 0;
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions = 0;
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_lookups = 0;
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_dummyHits = 0;
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#endif
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}
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/**
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* Copy constructor, creates a full copy of the given hashmap.
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* We must provide a custom copy constructor as we use pointers
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* to heap buffers for the internal storage.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::HashMap(const HM_t &map) :
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_defaultVal() {
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions = 0;
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_lookups = 0;
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_dummyHits = 0;
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#endif
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assign(map);
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}
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/**
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* Destructor, frees all used memory.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::~HashMap() {
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for (size_type ctr = 0; ctr <= _mask; ++ctr)
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freeNode(_storage[ctr]);
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delete[] _storage;
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#ifdef DEBUG_HASH_COLLISIONS
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extern void updateHashCollisionStats(int, int, int, int, int);
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updateHashCollisionStats(_collisions, _dummyHits, _lookups, _mask + 1, _size);
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#endif
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}
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/**
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* Internal method for assigning the content of another HashMap
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* to this one.
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*
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* @note We do *not* deallocate the previous storage here -- the caller is
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* responsible for doing that!
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::assign(const HM_t &map) {
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_mask = map._mask;
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_storage = new Node *[_mask + 1];
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assert(_storage != nullptr);
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memset(_storage, 0, (_mask + 1) * sizeof(Node *));
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// Simply clone the map given to us, one by one.
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_size = 0;
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_deleted = 0;
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for (size_type ctr = 0; ctr <= _mask; ++ctr) {
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if (map._storage[ctr] == HASHMAP_DUMMY_NODE) {
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_storage[ctr] = HASHMAP_DUMMY_NODE;
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_deleted++;
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} else if (map._storage[ctr] != nullptr) {
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_storage[ctr] = allocNode(map._storage[ctr]->_key);
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_storage[ctr]->_value = map._storage[ctr]->_value;
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_size++;
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}
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}
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// Perform a sanity check (to help track down hashmap corruption)
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assert(_size == map._size);
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assert(_deleted == map._deleted);
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::clear(bool shrinkArray) {
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for (size_type ctr = 0; ctr <= _mask; ++ctr) {
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freeNode(_storage[ctr]);
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_storage[ctr] = nullptr;
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}
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#ifdef USE_HASHMAP_MEMORY_POOL
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_nodePool.freeUnusedPages();
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#endif
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if (shrinkArray && _mask >= HASHMAP_MIN_CAPACITY) {
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delete[] _storage;
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_mask = HASHMAP_MIN_CAPACITY - 1;
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_storage = new Node *[HASHMAP_MIN_CAPACITY];
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assert(_storage != nullptr);
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memset(_storage, 0, HASHMAP_MIN_CAPACITY * sizeof(Node *));
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}
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_size = 0;
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_deleted = 0;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::expandStorage(size_type newCapacity) {
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assert(newCapacity > _mask + 1);
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#ifndef NDEBUG
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const size_type old_size = _size;
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#endif
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const size_type old_mask = _mask;
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Node **old_storage = _storage;
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// allocate a new array
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_size = 0;
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_deleted = 0;
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_mask = newCapacity - 1;
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_storage = new Node *[newCapacity];
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assert(_storage != nullptr);
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memset(_storage, 0, newCapacity * sizeof(Node *));
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// rehash all the old elements
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for (size_type ctr = 0; ctr <= old_mask; ++ctr) {
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if (old_storage[ctr] == nullptr || old_storage[ctr] == HASHMAP_DUMMY_NODE)
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continue;
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// Insert the element from the old table into the new table.
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// Since we know that no key exists twice in the old table, we
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// can do this slightly better than by calling lookup, since we
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// don't have to call _equal().
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const size_type hash = _hash(old_storage[ctr]->_key);
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size_type idx = hash & _mask;
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for (size_type perturb = hash; _storage[idx] != nullptr && _storage[idx] != HASHMAP_DUMMY_NODE; perturb >>= HASHMAP_PERTURB_SHIFT) {
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idx = (5 * idx + perturb + 1) & _mask;
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}
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_storage[idx] = old_storage[ctr];
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_size++;
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}
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// Perform a sanity check: Old number of elements should match the new one!
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// This check will fail if some previous operation corrupted this hashmap.
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assert(_size == old_size);
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delete[] old_storage;
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return;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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typename HashMap<Key, Val, HashFunc, EqualFunc>::size_type HashMap<Key, Val, HashFunc, EqualFunc>::lookup(const Key &key) const {
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const size_type hash = _hash(key);
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size_type ctr = hash & _mask;
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for (size_type perturb = hash; ; perturb >>= HASHMAP_PERTURB_SHIFT) {
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if (_storage[ctr] == nullptr)
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break;
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if (_storage[ctr] == HASHMAP_DUMMY_NODE) {
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#ifdef DEBUG_HASH_COLLISIONS
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_dummyHits++;
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#endif
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} else if (_equal(_storage[ctr]->_key, key))
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break;
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ctr = (5 * ctr + perturb + 1) & _mask;
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions++;
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#endif
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}
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#ifdef DEBUG_HASH_COLLISIONS
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_lookups++;
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debug("collisions %d, dummies hit %d, lookups %d, ratio %f in HashMap %p; size %d num elements %d",
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_collisions, _dummyHits, _lookups, ((double) _collisions / (double)_lookups),
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(const void *)this, _mask + 1, _size);
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#endif
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return ctr;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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typename HashMap<Key, Val, HashFunc, EqualFunc>::size_type HashMap<Key, Val, HashFunc, EqualFunc>::lookupAndCreateIfMissing(const Key &key) {
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const size_type hash = _hash(key);
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size_type ctr = hash & _mask;
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const size_type NONE_FOUND = _mask + 1;
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size_type first_free = NONE_FOUND;
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bool found = false;
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for (size_type perturb = hash; ; perturb >>= HASHMAP_PERTURB_SHIFT) {
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if (_storage[ctr] == nullptr)
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break;
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if (_storage[ctr] == HASHMAP_DUMMY_NODE) {
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#ifdef DEBUG_HASH_COLLISIONS
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_dummyHits++;
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#endif
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if (first_free == NONE_FOUND)
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first_free = ctr;
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} else if (_equal(_storage[ctr]->_key, key)) {
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found = true;
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break;
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}
|
|
|
|
ctr = (5 * ctr + perturb + 1) & _mask;
|
|
|
|
#ifdef DEBUG_HASH_COLLISIONS
|
|
_collisions++;
|
|
#endif
|
|
}
|
|
|
|
#ifdef DEBUG_HASH_COLLISIONS
|
|
_lookups++;
|
|
debug("collisions %d, dummies hit %d, lookups %d, ratio %f in HashMap %p; size %d num elements %d",
|
|
_collisions, _dummyHits, _lookups, ((double) _collisions / (double)_lookups),
|
|
(const void *)this, _mask + 1, _size);
|
|
#endif
|
|
|
|
if (!found && first_free != NONE_FOUND)
|
|
ctr = first_free;
|
|
|
|
if (!found) {
|
|
if (_storage[ctr])
|
|
_deleted--;
|
|
_storage[ctr] = allocNode(key);
|
|
assert(_storage[ctr] != nullptr);
|
|
_size++;
|
|
|
|
// Keep the load factor below a certain threshold.
|
|
// Deleted nodes are also counted
|
|
size_type capacity = _mask + 1;
|
|
if ((_size + _deleted) * HASHMAP_LOADFACTOR_DENOMINATOR >
|
|
capacity * HASHMAP_LOADFACTOR_NUMERATOR) {
|
|
capacity = capacity < 500 ? (capacity * 4) : (capacity * 2);
|
|
expandStorage(capacity);
|
|
ctr = lookup(key);
|
|
assert(_storage[ctr] != nullptr);
|
|
}
|
|
}
|
|
|
|
return ctr;
|
|
}
|
|
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
bool HashMap<Key, Val, HashFunc, EqualFunc>::contains(const Key &key) const {
|
|
size_type ctr = lookup(key);
|
|
return (_storage[ctr] != nullptr);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator[](const Key &key) {
|
|
return getVal(key);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator[](const Key &key) const {
|
|
return getVal(key);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key) {
|
|
size_type ctr = lookupAndCreateIfMissing(key);
|
|
assert(_storage[ctr] != nullptr);
|
|
return _storage[ctr]->_value;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key) const {
|
|
return getVal(key, _defaultVal);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key, const Val &defaultVal) const {
|
|
size_type ctr = lookup(key);
|
|
if (_storage[ctr] != nullptr)
|
|
return _storage[ctr]->_value;
|
|
else
|
|
return defaultVal;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::setVal(const Key &key, const Val &val) {
|
|
size_type ctr = lookupAndCreateIfMissing(key);
|
|
assert(_storage[ctr] != nullptr);
|
|
_storage[ctr]->_value = val;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::erase(iterator entry) {
|
|
// Check whether we have a valid iterator
|
|
assert(entry._hashmap == this);
|
|
const size_type ctr = entry._idx;
|
|
assert(ctr <= _mask);
|
|
Node * const node = _storage[ctr];
|
|
assert(node != NULL);
|
|
assert(node != HASHMAP_DUMMY_NODE);
|
|
|
|
// If we remove a key, we replace it with a dummy node.
|
|
freeNode(node);
|
|
_storage[ctr] = HASHMAP_DUMMY_NODE;
|
|
_size--;
|
|
_deleted++;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::erase(const Key &key) {
|
|
|
|
size_type ctr = lookup(key);
|
|
if (_storage[ctr] == nullptr)
|
|
return;
|
|
|
|
// If we remove a key, we replace it with a dummy node.
|
|
freeNode(_storage[ctr]);
|
|
_storage[ctr] = HASHMAP_DUMMY_NODE;
|
|
_size--;
|
|
_deleted++;
|
|
return;
|
|
}
|
|
|
|
#undef HASHMAP_DUMMY_NODE
|
|
|
|
} // End of namespace Common
|
|
|
|
#endif
|