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1 /*
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2 * Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // Inline function definitions for hashtable.hpp.
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26
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27
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28 // --------------------------------------------------------------------------
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29 // Hash function
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30
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31 // We originally used hashpjw, but hash P(31) gives just as good results
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32 // and is slighly faster. We would like a hash function that looks at every
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33 // character, since package names have large common prefixes, and also because
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34 // hash_or_fail does error checking while iterating.
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35
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36 // hash P(31) from Kernighan & Ritchie
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37
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38 inline unsigned int Hashtable::hash_symbol(const char* s, int len) {
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39 unsigned int h = 0;
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40 while (len-- > 0) {
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41 h = 31*h + (unsigned) *s;
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42 s++;
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43 }
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44 return h;
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45 }
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46
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47
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48 // --------------------------------------------------------------------------
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49
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50 // Initialize a table.
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51
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52 inline BasicHashtable::BasicHashtable(int table_size, int entry_size) {
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53 // Called on startup, no locking needed
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54 initialize(table_size, entry_size, 0);
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55 _buckets = NEW_C_HEAP_ARRAY(HashtableBucket, table_size);
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56 for (int index = 0; index < _table_size; index++) {
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57 _buckets[index].clear();
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58 }
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59 }
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60
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61
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62 inline BasicHashtable::BasicHashtable(int table_size, int entry_size,
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63 HashtableBucket* buckets,
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64 int number_of_entries) {
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65 // Called on startup, no locking needed
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66 initialize(table_size, entry_size, number_of_entries);
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67 _buckets = buckets;
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68 }
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69
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70
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71 inline void BasicHashtable::initialize(int table_size, int entry_size,
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72 int number_of_entries) {
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73 // Called on startup, no locking needed
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74 _table_size = table_size;
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75 _entry_size = entry_size;
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76 _free_list = NULL;
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77 _first_free_entry = NULL;
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78 _end_block = NULL;
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79 _number_of_entries = number_of_entries;
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80 #ifdef ASSERT
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81 _lookup_count = 0;
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82 _lookup_length = 0;
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83 #endif
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84 }
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85
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86
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87 // The following method is MT-safe and may be used with caution.
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88 inline BasicHashtableEntry* BasicHashtable::bucket(int i) {
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89 return _buckets[i].get_entry();
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90 }
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91
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92
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93 inline void HashtableBucket::set_entry(BasicHashtableEntry* l) {
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94 // Warning: Preserve store ordering. The SystemDictionary is read
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95 // without locks. The new SystemDictionaryEntry must be
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96 // complete before other threads can be allowed to see it
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97 // via a store to _buckets[index].
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98 OrderAccess::release_store_ptr(&_entry, l);
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99 }
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100
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101
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102 inline BasicHashtableEntry* HashtableBucket::get_entry() const {
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103 // Warning: Preserve load ordering. The SystemDictionary is read
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104 // without locks. The new SystemDictionaryEntry must be
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105 // complete before other threads can be allowed to see it
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106 // via a store to _buckets[index].
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107 return (BasicHashtableEntry*) OrderAccess::load_ptr_acquire(&_entry);
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108 }
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109
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110
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111 inline void BasicHashtable::set_entry(int index, BasicHashtableEntry* entry) {
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112 _buckets[index].set_entry(entry);
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113 }
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114
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115
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116 inline void BasicHashtable::add_entry(int index, BasicHashtableEntry* entry) {
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117 entry->set_next(bucket(index));
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118 _buckets[index].set_entry(entry);
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119 ++_number_of_entries;
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120 }
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121
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122 inline void BasicHashtable::free_entry(BasicHashtableEntry* entry) {
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123 entry->set_next(_free_list);
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124 _free_list = entry;
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125 --_number_of_entries;
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126 }
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