1 /*
2 * Copyright (c) 2012, 2018, 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<
36 typename K, typename V,
37 // xlC does not compile this:
38 // http://stackoverflow.com/questions/8532961/template-argument-of-type-that-is-defined-by-inner-typedef-from-other-template-c
39 //typename ResourceHashtableFns<K>::hash_fn HASH = primitive_hash<K>,
40 //typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
41 unsigned (*HASH) (K const&) = primitive_hash<K>,
42 bool (*EQUALS)(K const&, K const&) = primitive_equals<K>,
43 unsigned SIZE = 256,
44 ResourceObj::allocation_type ALLOC_TYPE = ResourceObj::RESOURCE_AREA,
45 MEMFLAGS MEM_TYPE = mtInternal
46 >
47 class ResourceHashtable : public ResourceObj {
48 private:
49
50 class Node : public ResourceObj {
51 public:
52 unsigned _hash;
53 K _key;
54 V _value;
55 Node* _next;
56
57 Node(unsigned hash, K const& key, V const& value) :
58 _hash(hash), _key(key), _value(value), _next(NULL) {}
59 };
60
61 Node* _table[SIZE];
62
63 // Returns a pointer to where the node where the value would reside if
64 // it's in the table.
65 Node** lookup_node(unsigned hash, K const& key) {
66 unsigned index = hash % SIZE;
67 Node** ptr = &_table[index];
68 while (*ptr != NULL) {
69 Node* node = *ptr;
70 if (node->_hash == hash && EQUALS(key, node->_key)) {
71 break;
72 }
73 ptr = &(node->_next);
74 }
75 return ptr;
76 }
77
78 Node const** lookup_node(unsigned hash, K const& key) const {
79 return const_cast<Node const**>(
80 const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
81 }
82
83 public:
84 ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
85
86 ~ResourceHashtable() {
87 if (ALLOC_TYPE == C_HEAP) {
88 Node* const* bucket = _table;
89 while (bucket < &_table[SIZE]) {
90 Node* node = *bucket;
91 while (node != NULL) {
92 Node* cur = node;
93 node = node->_next;
94 delete cur;
95 }
96 ++bucket;
97 }
98 }
99 }
100
101 bool contains(K const& key) const {
102 return get(key) != NULL;
103 }
104
105 V* get(K const& key) const {
106 unsigned hv = HASH(key);
107 Node const** ptr = lookup_node(hv, key);
108 if (*ptr != NULL) {
109 return const_cast<V*>(&(*ptr)->_value);
110 } else {
111 return NULL;
112 }
113 }
114
115 /**
116 * Inserts or replaces a value in the table.
117 * @return: true: if a new item is added
118 * false: if the item already existed and the value is updated
119 */
120 bool put(K const& key, V const& value) {
121 unsigned hv = HASH(key);
122 Node** ptr = lookup_node(hv, key);
123 if (*ptr != NULL) {
124 (*ptr)->_value = value;
125 return false;
126 } else {
127 *ptr = new (ALLOC_TYPE, MEM_TYPE) Node(hv, key, value);
128 return true;
129 }
130 }
131
132 bool remove(K const& key) {
133 unsigned hv = HASH(key);
134 Node** ptr = lookup_node(hv, key);
135
136 Node* node = *ptr;
137 if (node != NULL) {
138 *ptr = node->_next;
139 if (ALLOC_TYPE == C_HEAP) {
140 delete node;
141 }
142 return true;
143 }
144 return false;
145 }
146
147 // ITER contains bool do_entry(K const&, V const&), which will be
148 // called for each entry in the table. If do_entry() returns false,
149 // the iteration is cancelled.
150 template<class ITER>
151 void iterate(ITER* iter) const {
152 Node* const* bucket = _table;
153 while (bucket < &_table[SIZE]) {
154 Node* node = *bucket;
155 while (node != NULL) {
156 bool cont = iter->do_entry(node->_key, node->_value);
157 if (!cont) { return; }
158 node = node->_next;
159 }
160 ++bucket;
161 }
162 }
163
164 static size_t node_size() {
165 return sizeof(Node);
166 }
167 };
168
169
170 #endif // SHARE_VM_UTILITIES_RESOURCEHASH_HPP