1/*
2 * Copyright (c) 2012, 2019, 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_UTILITIES_RESOURCEHASH_HPP
26#define SHARE_UTILITIES_RESOURCEHASH_HPP
27
28#include "memory/allocation.hpp"
29
30template<
31 typename K, typename V,
32 // xlC does not compile this:
33 // http://stackoverflow.com/questions/8532961/template-argument-of-type-that-is-defined-by-inner-typedef-from-other-template-c
34 //typename ResourceHashtableFns<K>::hash_fn HASH = primitive_hash<K>,
35 //typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
36 unsigned (*HASH) (K const&) = primitive_hash<K>,
37 bool (*EQUALS)(K const&, K const&) = primitive_equals<K>,
38 unsigned SIZE = 256,
39 ResourceObj::allocation_type ALLOC_TYPE = ResourceObj::RESOURCE_AREA,
40 MEMFLAGS MEM_TYPE = mtInternal
41 >
42class ResourceHashtable : public ResourceObj {
43 private:
44
45 class Node : public ResourceObj {
46 public:
47 unsigned _hash;
48 K _key;
49 V _value;
50 Node* _next;
51
52 Node(unsigned hash, K const& key, V const& value) :
53 _hash(hash), _key(key), _value(value), _next(NULL) {}
54 };
55
56 Node* _table[SIZE];
57
58 // Returns a pointer to where the node where the value would reside if
59 // it's in the table.
60 Node** lookup_node(unsigned hash, K const& key) {
61 unsigned index = hash % SIZE;
62 Node** ptr = &_table[index];
63 while (*ptr != NULL) {
64 Node* node = *ptr;
65 if (node->_hash == hash && EQUALS(key, node->_key)) {
66 break;
67 }
68 ptr = &(node->_next);
69 }
70 return ptr;
71 }
72
73 Node const** lookup_node(unsigned hash, K const& key) const {
74 return const_cast<Node const**>(
75 const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
76 }
77
78 public:
79 ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
80
81 ~ResourceHashtable() {
82 if (ALLOC_TYPE == C_HEAP) {
83 Node* const* bucket = _table;
84 while (bucket < &_table[SIZE]) {
85 Node* node = *bucket;
86 while (node != NULL) {
87 Node* cur = node;
88 node = node->_next;
89 delete cur;
90 }
91 ++bucket;
92 }
93 }
94 }
95
96 bool contains(K const& key) const {
97 return get(key) != NULL;
98 }
99
100 V* get(K const& key) const {
101 unsigned hv = HASH(key);
102 Node const** ptr = lookup_node(hv, key);
103 if (*ptr != NULL) {
104 return const_cast<V*>(&(*ptr)->_value);
105 } else {
106 return NULL;
107 }
108 }
109
110 /**
111 * Inserts or replaces a value in the table.
112 * @return: true: if a new item is added
113 * false: if the item already existed and the value is updated
114 */
115 bool put(K const& key, V const& value) {
116 unsigned hv = HASH(key);
117 Node** ptr = lookup_node(hv, key);
118 if (*ptr != NULL) {
119 (*ptr)->_value = value;
120 return false;
121 } else {
122 *ptr = new (ALLOC_TYPE, MEM_TYPE) Node(hv, key, value);
123 return true;
124 }
125 }
126
127 bool remove(K const& key) {
128 unsigned hv = HASH(key);
129 Node** ptr = lookup_node(hv, key);
130
131 Node* node = *ptr;
132 if (node != NULL) {
133 *ptr = node->_next;
134 if (ALLOC_TYPE == C_HEAP) {
135 delete node;
136 }
137 return true;
138 }
139 return false;
140 }
141
142 // ITER contains bool do_entry(K const&, V const&), which will be
143 // called for each entry in the table. If do_entry() returns false,
144 // the iteration is cancelled.
145 template<class ITER>
146 void iterate(ITER* iter) const {
147 Node* const* bucket = _table;
148 while (bucket < &_table[SIZE]) {
149 Node* node = *bucket;
150 while (node != NULL) {
151 bool cont = iter->do_entry(node->_key, node->_value);
152 if (!cont) { return; }
153 node = node->_next;
154 }
155 ++bucket;
156 }
157 }
158};
159
160
161#endif // SHARE_UTILITIES_RESOURCEHASH_HPP
162