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comparison src/share/vm/utilities/resourceHash.hpp @ 6934:4735d2c84362

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7200776: Implement default methods in interfaces Summary: Add generic type analysis and default method selection algorithms Reviewed-by: coleenp, acorn
author kamg
date Thu, 11 Oct 2012 12:25:42 -0400
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6921:a1b8cf9cf970 6934:4735d2c84362
1 /*
2 * Copyright (c) 2012, 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 #include "utilities/top.hpp"
30
31 template<typename K> struct ResourceHashtableFns {
32 typedef unsigned (*hash_fn)(K const&);
33 typedef bool (*equals_fn)(K const&, K const&);
34 };
35
36 template<typename K> unsigned primitive_hash(const K& k) {
37 unsigned hash = (unsigned)((uintptr_t)k);
38 return hash ^ (hash > 3); // just in case we're dealing with aligned ptrs
39 }
40
41 template<typename K> bool primitive_equals(const K& k0, const K& k1) {
42 return k0 == k1;
43 }
44
45 template<
46 typename K, typename V,
47 typename ResourceHashtableFns<K>::hash_fn HASH = primitive_hash<K>,
48 typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
49 unsigned SIZE = 256
50 >
51 class ResourceHashtable : public ResourceObj {
52 private:
53
54 class Node : public ResourceObj {
55 public:
56 unsigned _hash;
57 K _key;
58 V _value;
59 Node* _next;
60
61 Node(unsigned hash, K const& key, V const& value) :
62 _hash(hash), _key(key), _value(value), _next(NULL) {}
63 };
64
65 Node* _table[SIZE];
66
67 // Returns a pointer to where the node where the value would reside if
68 // it's in the table.
69 Node** lookup_node(unsigned hash, K const& key) {
70 unsigned index = hash % SIZE;
71 Node** ptr = &_table[index];
72 while (*ptr != NULL) {
73 Node* node = *ptr;
74 if (node->_hash == hash && EQUALS(key, node->_key)) {
75 break;
76 }
77 ptr = &(node->_next);
78 }
79 return ptr;
80 }
81
82 Node const** lookup_node(unsigned hash, K const& key) const {
83 return const_cast<Node const**>(
84 const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
85 }
86
87 public:
88 ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
89
90 bool contains(K const& key) const {
91 return get(key) != NULL;
92 }
93
94 V* get(K const& key) const {
95 unsigned hv = HASH(key);
96 Node const** ptr = lookup_node(hv, key);
97 if (*ptr != NULL) {
98 return const_cast<V*>(&(*ptr)->_value);
99 } else {
100 return NULL;
101 }
102 }
103
104 // Inserts or replaces a value in the table
105 void put(K const& key, V const& value) {
106 unsigned hv = HASH(key);
107 Node** ptr = lookup_node(hv, key);
108 if (*ptr != NULL) {
109 (*ptr)->_value = value;
110 } else {
111 *ptr = new Node(hv, key, value);
112 }
113 }
114
115 // ITER contains bool do_entry(K const&, V const&), which will be
116 // called for each entry in the table. If do_entry() returns false,
117 // the iteration is cancelled.
118 template<class ITER>
119 void iterate(ITER* iter) const {
120 Node* const* bucket = _table;
121 while (bucket < &_table[SIZE]) {
122 Node* node = *bucket;
123 while (node != NULL) {
124 bool cont = iter->do_entry(node->_key, node->_value);
125 if (!cont) { return; }
126 node = node->_next;
127 }
128 ++bucket;
129 }
130 }
131 };
132
133
134 #endif // SHARE_VM_UTILITIES_RESOURCEHASH_HPP