1 /* 2 * Copyright (c) 2003, 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 // 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 }