1 /*
2 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_UTILITIES_RESOURCEHASH_HPP
26 #define SHARE_VM_UTILITIES_RESOURCEHASH_HPP
27
28 #include "memory/allocation.hpp"
29
30 template<typename K> struct ResourceHashtableFns {
31 typedef unsigned (*hash_fn)(K const&);
32 typedef bool (*equals_fn)(K const&, K const&);
33 };
34
35 template<typename K> unsigned primitive_hash(const K& k) {
36 unsigned hash = (unsigned)((uintptr_t)k);
37 return hash ^ (hash >> 3); // just in case we're dealing with aligned ptrs
38 }
39
40 template<typename K> bool primitive_equals(const K& k0, const K& k1) {
41 return k0 == k1;
42 }
43
44 template<
45 typename K, typename V,
46 // xlC does not compile this:
47 // http://stackoverflow.com/questions/8532961/template-argument-of-type-that-is-defined-by-inner-typedef-from-other-template-c
48 //typename ResourceHashtableFns<K>::hash_fn HASH = primitive_hash<K>,
49 //typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
50 unsigned (*HASH) (K const&) = primitive_hash<K>,
51 bool (*EQUALS)(K const&, K const&) = primitive_equals<K>,
52 unsigned SIZE = 256,
53 ResourceObj::allocation_type ALLOC_TYPE = ResourceObj::RESOURCE_AREA,
54 MEMFLAGS MEM_TYPE = mtInternal
55 >
56 class ResourceHashtable : public ResourceObj {
57 private:
58
59 class Node : public ResourceObj {
60 public:
61 unsigned _hash;
62 K _key;
63 V _value;
64 Node* _next;
65
66 Node(unsigned hash, K const& key, V const& value) :
67 _hash(hash), _key(key), _value(value), _next(NULL) {}
68 };
69
70 Node* _table[SIZE];
71
72 // Returns a pointer to where the node where the value would reside if
73 // it's in the table.
74 Node** lookup_node(unsigned hash, K const& key) {
75 unsigned index = hash % SIZE;
76 Node** ptr = &_table[index];
77 while (*ptr != NULL) {
78 Node* node = *ptr;
79 if (node->_hash == hash && EQUALS(key, node->_key)) {
80 break;
81 }
82 ptr = &(node->_next);
83 }
84 return ptr;
85 }
86
87 Node const** lookup_node(unsigned hash, K const& key) const {
88 return const_cast<Node const**>(
89 const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
90 }
91
92 public:
93 ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
94
95 ~ResourceHashtable() {
96 if (ALLOC_TYPE == C_HEAP) {
97 Node* const* bucket = _table;
98 while (bucket < &_table[SIZE]) {
99 Node* node = *bucket;
100 while (node != NULL) {
101 Node* cur = node;
102 node = node->_next;
103 delete cur;
104 }
105 ++bucket;
106 }
107 }
108 }
109
110 bool contains(K const& key) const {
111 return get(key) != NULL;
112 }
113
114 V* get(K const& key) const {
115 unsigned hv = HASH(key);
116 Node const** ptr = lookup_node(hv, key);
117 if (*ptr != NULL) {
118 return const_cast<V*>(&(*ptr)->_value);
119 } else {
120 return NULL;
121 }
122 }
123
124 /**
125 * Inserts or replaces a value in the table.
126 * @return: true: if a new item is added
127 * false: if the item already existed and the value is updated
128 */
129 bool put(K const& key, V const& value) {
130 unsigned hv = HASH(key);
131 Node** ptr = lookup_node(hv, key);
132 if (*ptr != NULL) {
133 (*ptr)->_value = value;
134 return false;
135 } else {
136 *ptr = new (ALLOC_TYPE, MEM_TYPE) Node(hv, key, value);
137 return true;
138 }
139 }
140
141 bool remove(K const& key) {
142 unsigned hv = HASH(key);
143 Node** ptr = lookup_node(hv, key);
144
145 Node* node = *ptr;
146 if (node != NULL) {
147 *ptr = node->_next;
148 if (ALLOC_TYPE == C_HEAP) {
149 delete node;
150 }
151 return true;
152 }
153 return false;
154 }
155
156 // ITER contains bool do_entry(K const&, V const&), which will be
157 // called for each entry in the table. If do_entry() returns false,
158 // the iteration is cancelled.
159 template<class ITER>
160 void iterate(ITER* iter) const {
161 Node* const* bucket = _table;
162 while (bucket < &_table[SIZE]) {
163 Node* node = *bucket;
164 while (node != NULL) {
165 bool cont = iter->do_entry(node->_key, node->_value);
166 if (!cont) { return; }
167 node = node->_next;
168 }
169 ++bucket;
170 }
171 }
172
173 static size_t node_size() {
174 return sizeof(Node);
175 }
176 };
177
178
179 #endif // SHARE_VM_UTILITIES_RESOURCEHASH_HPP