hashtable.inline.hpp revision 2273:1d1603768966 
1/*
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24
25#ifndef SHARE_VM_UTILITIES_HASHTABLE_INLINE_HPP
26#define SHARE_VM_UTILITIES_HASHTABLE_INLINE_HPP
27
28#include "memory/allocation.inline.hpp"
29#include "utilities/hashtable.hpp"
30
31// Inline function definitions for hashtable.hpp.
32
33
34// --------------------------------------------------------------------------
35// Hash function
36
37// We originally used hashpjw, but hash P(31) gives just as good results
38// and is slighly faster. We would like a hash function that looks at every
39// character, since package names have large common prefixes, and also because
40// hash_or_fail does error checking while iterating.
41
42// hash P(31) from Kernighan & Ritchie
43
44inline unsigned int BasicHashtable::hash_symbol(const char* s, int len) {
45  unsigned int h = 0;
46  while (len-- > 0) {
47    h = 31*h + (unsigned) *s;
48    s++;
49  }
50  return h;
51}
52
53
54// --------------------------------------------------------------------------
55
56// Initialize a table.
57
58inline BasicHashtable::BasicHashtable(int table_size, int entry_size) {
59  // Called on startup, no locking needed
60  initialize(table_size, entry_size, 0);
61  _buckets = NEW_C_HEAP_ARRAY(HashtableBucket, table_size);
62  for (int index = 0; index < _table_size; index++) {
63    _buckets[index].clear();
64  }
65}
66
67
68inline BasicHashtable::BasicHashtable(int table_size, int entry_size,
69                                      HashtableBucket* buckets,
70                                      int number_of_entries) {
71  // Called on startup, no locking needed
72  initialize(table_size, entry_size, number_of_entries);
73  _buckets = buckets;
74}
75
76
77inline void BasicHashtable::initialize(int table_size, int entry_size,
78                                       int number_of_entries) {
79  // Called on startup, no locking needed
80  _table_size = table_size;
81  _entry_size = entry_size;
82  _free_list = NULL;
83  _first_free_entry = NULL;
84  _end_block = NULL;
85  _number_of_entries = number_of_entries;
86#ifdef ASSERT
87  _lookup_count = 0;
88  _lookup_length = 0;
89#endif
90}
91
92
93// The following method is MT-safe and may be used with caution.
94inline BasicHashtableEntry* BasicHashtable::bucket(int i) {
95  return _buckets[i].get_entry();
96}
97
98
99inline void HashtableBucket::set_entry(BasicHashtableEntry* l) {
100  // Warning: Preserve store ordering.  The SystemDictionary is read
101  //          without locks.  The new SystemDictionaryEntry must be
102  //          complete before other threads can be allowed to see it
103  //          via a store to _buckets[index].
104  OrderAccess::release_store_ptr(&_entry, l);
105}
106
107
108inline BasicHashtableEntry* HashtableBucket::get_entry() const {
109  // Warning: Preserve load ordering.  The SystemDictionary is read
110  //          without locks.  The new SystemDictionaryEntry must be
111  //          complete before other threads can be allowed to see it
112  //          via a store to _buckets[index].
113  return (BasicHashtableEntry*) OrderAccess::load_ptr_acquire(&_entry);
114}
115
116
117inline void BasicHashtable::set_entry(int index, BasicHashtableEntry* entry) {
118  _buckets[index].set_entry(entry);
119}
120
121
122inline void BasicHashtable::add_entry(int index, BasicHashtableEntry* entry) {
123  entry->set_next(bucket(index));
124  _buckets[index].set_entry(entry);
125  ++_number_of_entries;
126}
127
128inline void BasicHashtable::free_entry(BasicHashtableEntry* entry) {
129  entry->set_next(_free_list);
130  _free_list = entry;
131  --_number_of_entries;
132}
133
134#endif // SHARE_VM_UTILITIES_HASHTABLE_INLINE_HPP
135