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comparison src/share/vm/utilities/hashtable.inline.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 2003 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Inline function definitions for hashtable.hpp.
26
27
28 // --------------------------------------------------------------------------
29 // Hash function
30
31 // We originally used hashpjw, but hash P(31) gives just as good results
32 // and is slighly faster. We would like a hash function that looks at every
33 // character, since package names have large common prefixes, and also because
34 // hash_or_fail does error checking while iterating.
35
36 // hash P(31) from Kernighan & Ritchie
37
38 inline unsigned int Hashtable::hash_symbol(const char* s, int len) {
39 unsigned int h = 0;
40 while (len-- > 0) {
41 h = 31*h + (unsigned) *s;
42 s++;
43 }
44 return h;
45 }
46
47
48 // --------------------------------------------------------------------------
49
50 // Initialize a table.
51
52 inline BasicHashtable::BasicHashtable(int table_size, int entry_size) {
53 // Called on startup, no locking needed
54 initialize(table_size, entry_size, 0);
55 _buckets = NEW_C_HEAP_ARRAY(HashtableBucket, table_size);
56 for (int index = 0; index < _table_size; index++) {
57 _buckets[index].clear();
58 }
59 }
60
61
62 inline BasicHashtable::BasicHashtable(int table_size, int entry_size,
63 HashtableBucket* buckets,
64 int number_of_entries) {
65 // Called on startup, no locking needed
66 initialize(table_size, entry_size, number_of_entries);
67 _buckets = buckets;
68 }
69
70
71 inline void BasicHashtable::initialize(int table_size, int entry_size,
72 int number_of_entries) {
73 // Called on startup, no locking needed
74 _table_size = table_size;
75 _entry_size = entry_size;
76 _free_list = NULL;
77 _first_free_entry = NULL;
78 _end_block = NULL;
79 _number_of_entries = number_of_entries;
80 #ifdef ASSERT
81 _lookup_count = 0;
82 _lookup_length = 0;
83 #endif
84 }
85
86
87 // The following method is MT-safe and may be used with caution.
88 inline BasicHashtableEntry* BasicHashtable::bucket(int i) {
89 return _buckets[i].get_entry();
90 }
91
92
93 inline void HashtableBucket::set_entry(BasicHashtableEntry* l) {
94 // Warning: Preserve store ordering. The SystemDictionary is read
95 // without locks. The new SystemDictionaryEntry must be
96 // complete before other threads can be allowed to see it
97 // via a store to _buckets[index].
98 OrderAccess::release_store_ptr(&_entry, l);
99 }
100
101
102 inline BasicHashtableEntry* HashtableBucket::get_entry() const {
103 // Warning: Preserve load ordering. The SystemDictionary is read
104 // without locks. The new SystemDictionaryEntry must be
105 // complete before other threads can be allowed to see it
106 // via a store to _buckets[index].
107 return (BasicHashtableEntry*) OrderAccess::load_ptr_acquire(&_entry);
108 }
109
110
111 inline void BasicHashtable::set_entry(int index, BasicHashtableEntry* entry) {
112 _buckets[index].set_entry(entry);
113 }
114
115
116 inline void BasicHashtable::add_entry(int index, BasicHashtableEntry* entry) {
117 entry->set_next(bucket(index));
118 _buckets[index].set_entry(entry);
119 ++_number_of_entries;
120 }
121
122 inline void BasicHashtable::free_entry(BasicHashtableEntry* entry) {
123 entry->set_next(_free_list);
124 _free_list = entry;
125 --_number_of_entries;
126 }