1 /*
2 * Copyright (c) 2003, 2019, 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.
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23 */
24
25 #ifndef SHARE_UTILITIES_HASHTABLE_HPP
26 #define SHARE_UTILITIES_HASHTABLE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "oops/oop.hpp"
30 #include "oops/symbol.hpp"
31 #include "runtime/handles.hpp"
32 #include "utilities/growableArray.hpp"
33
34 // This is a generic hashtable, designed to be used for the symbol
35 // and string tables.
36 //
37 // It is implemented as an open hash table with a fixed number of buckets.
38 //
39 // %note:
40 // - TableEntrys are allocated in blocks to reduce the space overhead.
41
42
43
44 template <MEMFLAGS F> class BasicHashtableEntry : public CHeapObj<F> {
45 friend class VMStructs;
46 private:
47 unsigned int _hash; // 32-bit hash for item
48
49 // Link to next element in the linked list for this bucket. EXCEPT
50 // bit 0 set indicates that this entry is shared and must not be
51 // unlinked from the table. Bit 0 is set during the dumping of the
52 // archive. Since shared entries are immutable, _next fields in the
53 // shared entries will not change. New entries will always be
54 // unshared and since pointers are align, bit 0 will always remain 0
55 // with no extra effort.
56 BasicHashtableEntry<F>* _next;
57
58 // Windows IA64 compiler requires subclasses to be able to access these
59 protected:
60 // Entry objects should not be created, they should be taken from the
61 // free list with BasicHashtable.new_entry().
62 BasicHashtableEntry() { ShouldNotReachHere(); }
63 // Entry objects should not be destroyed. They should be placed on
64 // the free list instead with BasicHashtable.free_entry().
65 ~BasicHashtableEntry() { ShouldNotReachHere(); }
66
67 public:
68
69 unsigned int hash() const { return _hash; }
70 void set_hash(unsigned int hash) { _hash = hash; }
71 unsigned int* hash_addr() { return &_hash; }
72
73 static BasicHashtableEntry<F>* make_ptr(BasicHashtableEntry<F>* p) {
74 return (BasicHashtableEntry*)((intptr_t)p & -2);
75 }
76
77 BasicHashtableEntry<F>* next() const {
78 return make_ptr(_next);
79 }
80
81 void set_next(BasicHashtableEntry<F>* next) {
82 _next = next;
83 }
84
85 BasicHashtableEntry<F>** next_addr() {
86 return &_next;
87 }
88
89 bool is_shared() const {
90 return ((intptr_t)_next & 1) != 0;
91 }
92
93 void set_shared() {
94 _next = (BasicHashtableEntry<F>*)((intptr_t)_next | 1);
95 }
96 };
97
98
99
100 template <class T, MEMFLAGS F> class HashtableEntry : public BasicHashtableEntry<F> {
101 friend class VMStructs;
102 private:
103 T _literal; // ref to item in table.
104
105 public:
106 // Literal
107 T literal() const { return _literal; }
108 T* literal_addr() { return &_literal; }
109 void set_literal(T s) { _literal = s; }
110
111 HashtableEntry* next() const {
112 return (HashtableEntry*)BasicHashtableEntry<F>::next();
113 }
114 HashtableEntry** next_addr() {
115 return (HashtableEntry**)BasicHashtableEntry<F>::next_addr();
116 }
117 };
118
119
120
121 template <MEMFLAGS F> class HashtableBucket : public CHeapObj<F> {
122 friend class VMStructs;
123 private:
124 // Instance variable
125 BasicHashtableEntry<F>* _entry;
126
127 public:
128 // Accessing
129 void clear() { _entry = NULL; }
130
131 // The following methods use order access methods to avoid race
132 // conditions in multiprocessor systems.
133 BasicHashtableEntry<F>* get_entry() const;
134 void set_entry(BasicHashtableEntry<F>* l);
135
136 // The following method is not MT-safe and must be done under lock.
137 BasicHashtableEntry<F>** entry_addr() { return &_entry; }
138
139 };
140
141
142 template <MEMFLAGS F> class BasicHashtable : public CHeapObj<F> {
143 friend class VMStructs;
144
145 public:
146 BasicHashtable(int table_size, int entry_size);
147 BasicHashtable(int table_size, int entry_size,
148 HashtableBucket<F>* buckets, int number_of_entries);
149 ~BasicHashtable();
150
151 // Bucket handling
152 int hash_to_index(unsigned int full_hash) const {
153 int h = full_hash % _table_size;
154 assert(h >= 0 && h < _table_size, "Illegal hash value");
155 return h;
156 }
157
158 private:
159 // Instance variables
160 int _table_size;
161 HashtableBucket<F>* _buckets;
162 BasicHashtableEntry<F>* volatile _free_list;
163 char* _first_free_entry;
164 char* _end_block;
165 int _entry_size;
166 volatile int _number_of_entries;
167 GrowableArray<char*>* _entry_blocks;
168
169 protected:
170
171 void initialize(int table_size, int entry_size, int number_of_entries);
172
173 // Accessor
174 int entry_size() const { return _entry_size; }
175
176 // The following method is MT-safe and may be used with caution.
177 BasicHashtableEntry<F>* bucket(int i) const;
178
179 // The following method is not MT-safe and must be done under lock.
180 BasicHashtableEntry<F>** bucket_addr(int i) { return _buckets[i].entry_addr(); }
181
182 // Attempt to get an entry from the free list
183 BasicHashtableEntry<F>* new_entry_free_list();
184
185 // Table entry management
186 BasicHashtableEntry<F>* new_entry(unsigned int hashValue);
187
188 // Used when moving the entry to another table
189 // Clean up links, but do not add to free_list
190 void unlink_entry(BasicHashtableEntry<F>* entry) {
191 entry->set_next(NULL);
192 --_number_of_entries;
193 }
194
195 // Move over freelist and free block for allocation
196 void copy_freelist(BasicHashtable* src) {
197 _free_list = src->_free_list;
198 src->_free_list = NULL;
199 _first_free_entry = src->_first_free_entry;
200 src->_first_free_entry = NULL;
201 _end_block = src->_end_block;
202 src->_end_block = NULL;
203 }
204
205 // Free the buckets in this hashtable
206 void free_buckets();
207 public:
208 int table_size() const { return _table_size; }
209 void set_entry(int index, BasicHashtableEntry<F>* entry);
210
211 void add_entry(int index, BasicHashtableEntry<F>* entry);
212
213 void free_entry(BasicHashtableEntry<F>* entry);
214
215 int number_of_entries() const { return _number_of_entries; }
216
217 bool resize(int new_size);
218
219 // Grow the number of buckets if the average entries per bucket is over the load_factor
220 bool maybe_grow(int max_size, int load_factor = 8);
221
222 template <class T> void verify_table(const char* table_name) PRODUCT_RETURN;
223 };
224
225
226 template <class T, MEMFLAGS F> class Hashtable : public BasicHashtable<F> {
227 friend class VMStructs;
228
229 public:
230 Hashtable(int table_size, int entry_size)
231 : BasicHashtable<F>(table_size, entry_size) { }
232
233 Hashtable(int table_size, int entry_size,
234 HashtableBucket<F>* buckets, int number_of_entries)
235 : BasicHashtable<F>(table_size, entry_size, buckets, number_of_entries) { }
236
237 // Debugging
238 void print() PRODUCT_RETURN;
239
240 unsigned int compute_hash(const Symbol* name) const {
241 return (unsigned int) name->identity_hash();
242 }
243
244 int index_for(const Symbol* name) const {
245 return this->hash_to_index(compute_hash(name));
246 }
247
248 void print_table_statistics(outputStream* st, const char *table_name, T (*literal_load_barrier)(HashtableEntry<T, F>*) = NULL);
249
250 protected:
251
252 // Table entry management
253 HashtableEntry<T, F>* new_entry(unsigned int hashValue, T obj);
254 // Don't create and use freelist of HashtableEntry.
255 HashtableEntry<T, F>* allocate_new_entry(unsigned int hashValue, T obj);
256
257 // The following method is MT-safe and may be used with caution.
258 HashtableEntry<T, F>* bucket(int i) const {
259 return (HashtableEntry<T, F>*)BasicHashtable<F>::bucket(i);
260 }
261
262 // The following method is not MT-safe and must be done under lock.
263 HashtableEntry<T, F>** bucket_addr(int i) {
264 return (HashtableEntry<T, F>**)BasicHashtable<F>::bucket_addr(i);
265 }
266 };
267
268 // A subclass of BasicHashtable that allows you to do a simple K -> V mapping
269 // without using tons of boilerplate code.
270 template<
271 typename K, typename V, MEMFLAGS F,
272 unsigned (*HASH) (K const&) = primitive_hash<K>,
273 bool (*EQUALS)(K const&, K const&) = primitive_equals<K>
274 >
275 class KVHashtable : public BasicHashtable<F> {
276 class KVHashtableEntry : public BasicHashtableEntry<F> {
277 public:
278 K _key;
279 V _value;
280 KVHashtableEntry* next() {
281 return (KVHashtableEntry*)BasicHashtableEntry<F>::next();
282 }
283 };
284
285 protected:
286 KVHashtableEntry* bucket(int i) const {
287 return (KVHashtableEntry*)BasicHashtable<F>::bucket(i);
288 }
289
290 KVHashtableEntry* new_entry(unsigned int hashValue, K key, V value) {
291 KVHashtableEntry* entry = (KVHashtableEntry*)BasicHashtable<F>::new_entry(hashValue);
292 entry->_key = key;
293 entry->_value = value;
294 return entry;
295 }
296
297 public:
298 KVHashtable(int table_size) : BasicHashtable<F>(table_size, sizeof(KVHashtableEntry)) {}
299
300 void add(K key, V value) {
301 unsigned int hash = HASH(key);
302 KVHashtableEntry* entry = new_entry(hash, key, value);
303 BasicHashtable<F>::add_entry(BasicHashtable<F>::hash_to_index(hash), entry);
304 }
305
306 V* lookup(K key) {
307 unsigned int hash = HASH(key);
308 int index = BasicHashtable<F>::hash_to_index(hash);
309 for (KVHashtableEntry* e = bucket(index); e != NULL; e = e->next()) {
310 if (e->hash() == hash && e->_key == key) {
311 return &(e->_value);
312 }
313 }
314 return NULL;
315 }
316 };
317
318
319 #endif // SHARE_UTILITIES_HASHTABLE_HPP