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/*
* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_VM_UTILITIES_RESOURCEHASH_HPP
#define SHARE_VM_UTILITIES_RESOURCEHASH_HPP
#include "memory/allocation.hpp"
#include "utilities/top.hpp"
template<typename K> struct ResourceHashtableFns {
typedef unsigned (*hash_fn)(K const&);
typedef bool (*equals_fn)(K const&, K const&);
};
template<typename K> unsigned primitive_hash(const K& k) {
unsigned hash = (unsigned)((uintptr_t)k);
return hash ^ (hash > 3); // just in case we're dealing with aligned ptrs
}
template<typename K> bool primitive_equals(const K& k0, const K& k1) {
return k0 == k1;
}
template<
typename K, typename V,
// xlC does not compile this:
// http://stackoverflow.com/questions/8532961/template-argument-of-type-that-is-defined-by-inner-typedef-from-other-template-c
//typename ResourceHashtableFns<K>::hash_fn HASH = primitive_hash<K>,
//typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
unsigned (*HASH) (K const&) = primitive_hash<K>,
bool (*EQUALS)(K const&, K const&) = primitive_equals<K>,
unsigned SIZE = 256
>
class ResourceHashtable : public ResourceObj {
private:
class Node : public ResourceObj {
public:
unsigned _hash;
K _key;
V _value;
Node* _next;
Node(unsigned hash, K const& key, V const& value) :
_hash(hash), _key(key), _value(value), _next(NULL) {}
};
Node* _table[SIZE];
// Returns a pointer to where the node where the value would reside if
// it's in the table.
Node** lookup_node(unsigned hash, K const& key) {
unsigned index = hash % SIZE;
Node** ptr = &_table[index];
while (*ptr != NULL) {
Node* node = *ptr;
if (node->_hash == hash && EQUALS(key, node->_key)) {
break;
}
ptr = &(node->_next);
}
return ptr;
}
Node const** lookup_node(unsigned hash, K const& key) const {
return const_cast<Node const**>(
const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
}
public:
ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
bool contains(K const& key) const {
return get(key) != NULL;
}
V* get(K const& key) const {
unsigned hv = HASH(key);
Node const** ptr = lookup_node(hv, key);
if (*ptr != NULL) {
return const_cast<V*>(&(*ptr)->_value);
} else {
return NULL;
}
}
// Inserts or replaces a value in the table
void put(K const& key, V const& value) {
unsigned hv = HASH(key);
Node** ptr = lookup_node(hv, key);
if (*ptr != NULL) {
(*ptr)->_value = value;
} else {
*ptr = new Node(hv, key, value);
}
}
// ITER contains bool do_entry(K const&, V const&), which will be
// called for each entry in the table. If do_entry() returns false,
// the iteration is cancelled.
template<class ITER>
void iterate(ITER* iter) const {
Node* const* bucket = _table;
while (bucket < &_table[SIZE]) {
Node* node = *bucket;
while (node != NULL) {
bool cont = iter->do_entry(node->_key, node->_value);
if (!cont) { return; }
node = node->_next;
}
++bucket;
}
}
};
#endif // SHARE_VM_UTILITIES_RESOURCEHASH_HPP
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