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comparison src/share/vm/utilities/hashtable.cpp @ 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 2003-2005 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 # include "incls/_precompiled.incl"
26 # include "incls/_hashtable.cpp.incl"
27
28 HS_DTRACE_PROBE_DECL4(hs_private, hashtable__new_entry,
29 void*, unsigned int, oop, void*);
30
31 // This is a generic hashtable, designed to be used for the symbol
32 // and string tables.
33 //
34 // It is implemented as an open hash table with a fixed number of buckets.
35 //
36 // %note:
37 // - HashtableEntrys are allocated in blocks to reduce the space overhead.
38
39 BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) {
40 BasicHashtableEntry* entry;
41
42 if (_free_list) {
43 entry = _free_list;
44 _free_list = _free_list->next();
45 } else {
46 const int block_size = 500;
47 if (_first_free_entry == _end_block) {
48 int len = _entry_size * block_size;
49 _first_free_entry = NEW_C_HEAP_ARRAY(char, len);
50 _end_block = _first_free_entry + len;
51 }
52 entry = (BasicHashtableEntry*)_first_free_entry;
53 _first_free_entry += _entry_size;
54 }
55
56 entry->set_hash(hashValue);
57 return entry;
58 }
59
60
61 HashtableEntry* Hashtable::new_entry(unsigned int hashValue, oop obj) {
62 HashtableEntry* entry;
63
64 entry = (HashtableEntry*)BasicHashtable::new_entry(hashValue);
65 entry->set_literal(obj); // clears literal string field
66 HS_DTRACE_PROBE4(hs_private, hashtable__new_entry,
67 this, hashValue, obj, entry);
68 return entry;
69 }
70
71
72 // GC support
73
74 void Hashtable::unlink(BoolObjectClosure* is_alive) {
75 // Readers of the table are unlocked, so we should only be removing
76 // entries at a safepoint.
77 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
78 for (int i = 0; i < table_size(); ++i) {
79 for (HashtableEntry** p = bucket_addr(i); *p != NULL; ) {
80 HashtableEntry* entry = *p;
81 if (entry->is_shared()) {
82 break;
83 }
84 assert(entry->literal() != NULL, "just checking");
85 if (is_alive->do_object_b(entry->literal())) {
86 p = entry->next_addr();
87 } else {
88 *p = entry->next();
89 free_entry(entry);
90 }
91 }
92 }
93 }
94
95
96 void Hashtable::oops_do(OopClosure* f) {
97 for (int i = 0; i < table_size(); ++i) {
98 HashtableEntry** p = bucket_addr(i);
99 HashtableEntry* entry = bucket(i);
100 while (entry != NULL) {
101 f->do_oop(entry->literal_addr());
102
103 // Did the closure remove the literal from the table?
104 if (entry->literal() == NULL) {
105 assert(!entry->is_shared(), "immutable hashtable entry?");
106 *p = entry->next();
107 free_entry(entry);
108 } else {
109 p = entry->next_addr();
110 }
111 entry = (HashtableEntry*)HashtableEntry::make_ptr(*p);
112 }
113 }
114 }
115
116
117 // Reverse the order of elements in the hash buckets.
118
119 void BasicHashtable::reverse() {
120
121 for (int i = 0; i < _table_size; ++i) {
122 BasicHashtableEntry* new_list = NULL;
123 BasicHashtableEntry* p = bucket(i);
124 while (p != NULL) {
125 BasicHashtableEntry* next = p->next();
126 p->set_next(new_list);
127 new_list = p;
128 p = next;
129 }
130 *bucket_addr(i) = new_list;
131 }
132 }
133
134
135 // Copy the table to the shared space.
136
137 void BasicHashtable::copy_table(char** top, char* end) {
138
139 // Dump the hash table entries.
140
141 intptr_t *plen = (intptr_t*)(*top);
142 *top += sizeof(*plen);
143
144 int i;
145 for (i = 0; i < _table_size; ++i) {
146 for (BasicHashtableEntry** p = _buckets[i].entry_addr();
147 *p != NULL;
148 p = (*p)->next_addr()) {
149 if (*top + entry_size() > end) {
150 warning("\nThe shared miscellaneous data space is not large "
151 "enough to \npreload requested classes. Use "
152 "-XX:SharedMiscDataSize= to increase \nthe initial "
153 "size of the miscellaneous data space.\n");
154 exit(2);
155 }
156 *p = (BasicHashtableEntry*)memcpy(*top, *p, entry_size());
157 *top += entry_size();
158 }
159 }
160 *plen = (char*)(*top) - (char*)plen - sizeof(*plen);
161
162 // Set the shared bit.
163
164 for (i = 0; i < _table_size; ++i) {
165 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) {
166 p->set_shared();
167 }
168 }
169 }
170
171
172
173 // Reverse the order of elements in the hash buckets.
174
175 void Hashtable::reverse(void* boundary) {
176
177 for (int i = 0; i < table_size(); ++i) {
178 HashtableEntry* high_list = NULL;
179 HashtableEntry* low_list = NULL;
180 HashtableEntry* last_low_entry = NULL;
181 HashtableEntry* p = bucket(i);
182 while (p != NULL) {
183 HashtableEntry* next = p->next();
184 if ((void*)p->literal() >= boundary) {
185 p->set_next(high_list);
186 high_list = p;
187 } else {
188 p->set_next(low_list);
189 low_list = p;
190 if (last_low_entry == NULL) {
191 last_low_entry = p;
192 }
193 }
194 p = next;
195 }
196 if (low_list != NULL) {
197 *bucket_addr(i) = low_list;
198 last_low_entry->set_next(high_list);
199 } else {
200 *bucket_addr(i) = high_list;
201 }
202 }
203 }
204
205
206 // Dump the hash table buckets.
207
208 void BasicHashtable::copy_buckets(char** top, char* end) {
209 intptr_t len = _table_size * sizeof(HashtableBucket);
210 *(intptr_t*)(*top) = len;
211 *top += sizeof(intptr_t);
212
213 *(intptr_t*)(*top) = _number_of_entries;
214 *top += sizeof(intptr_t);
215
216 if (*top + len > end) {
217 warning("\nThe shared miscellaneous data space is not large "
218 "enough to \npreload requested classes. Use "
219 "-XX:SharedMiscDataSize= to increase \nthe initial "
220 "size of the miscellaneous data space.\n");
221 exit(2);
222 }
223 _buckets = (HashtableBucket*)memcpy(*top, _buckets, len);
224 *top += len;
225 }
226
227
228 #ifndef PRODUCT
229
230 void Hashtable::print() {
231 ResourceMark rm;
232
233 for (int i = 0; i < table_size(); i++) {
234 HashtableEntry* entry = bucket(i);
235 while(entry != NULL) {
236 tty->print("%d : ", i);
237 entry->literal()->print();
238 tty->cr();
239 entry = entry->next();
240 }
241 }
242 }
243
244
245 void BasicHashtable::verify() {
246 int count = 0;
247 for (int i = 0; i < table_size(); i++) {
248 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) {
249 ++count;
250 }
251 }
252 assert(count == number_of_entries(), "number of hashtable entries incorrect");
253 }
254
255
256 #endif // PRODUCT
257
258
259 #ifdef ASSERT
260
261 void BasicHashtable::verify_lookup_length(double load) {
262 if ((double)_lookup_length / (double)_lookup_count > load * 2.0) {
263 warning("Performance bug: SystemDictionary lookup_count=%d "
264 "lookup_length=%d average=%lf load=%f",
265 _lookup_count, _lookup_length,
266 (double) _lookup_length / _lookup_count, load);
267 }
268 }
269
270 #endif