1 /**
2 * \file hash.h
3 * Generic hash table.
4 */
5
6 /*
7 * Mesa 3-D graphics library
8 *
9 * Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
10 *
11 * Permission is hereby granted, free of charge, to any person obtaining a
12 * copy of this software and associated documentation files (the "Software"),
13 * to deal in the Software without restriction, including without limitation
14 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
15 * and/or sell copies of the Software, and to permit persons to whom the
16 * Software is furnished to do so, subject to the following conditions:
17 *
18 * The above copyright notice and this permission notice shall be included
19 * in all copies or substantial portions of the Software.
20 *
21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
22 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
24 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
25 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
26 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
27 * OTHER DEALINGS IN THE SOFTWARE.
28 */
29
30
31 #ifndef HASH_H
32 #define HASH_H
33
34
35 #include <stdbool.h>
36 #include <stdint.h>
37 #include "glheader.h"
38
39 #include "c11/threads.h"
40
41 struct util_idalloc;
42
43 /**
44 * Magic GLuint object name that gets stored outside of the struct hash_table.
45 *
46 * The hash table needs a particular pointer to be the marker for a key that
47 * was deleted from the table, along with NULL for the "never allocated in the
48 * table" marker. Legacy GL allows any GLuint to be used as a GL object name,
49 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be
50 * able to track a GLuint that happens to match the deleted key outside of
51 * struct hash_table. We tell the hash table to use "1" as the deleted key
52 * value, so that we test the deleted-key-in-the-table path as best we can.
53 */
54 #define DELETED_KEY_VALUE 1
55
56 /** @{
57 * Mapping from our use of GLuint as both the key and the hash value to the
58 * hash_table.h API
59 *
60 * There exist many integer hash functions, designed to avoid collisions when
61 * the integers are spread across key space with some patterns. In GL, the
62 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
63 * contiguous integers starting from 1. Because of that, we just use the key
64 * as the hash value, to minimize the cost of the hash function. If objects
65 * are never deleted, we will never see a collision in the table, because the
66 * table resizes itself when it approaches full, and thus key % table_size ==
67 * key.
68 *
69 * The case where we could have collisions for genned objects would be
70 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
71 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
72 * the end of that sequence, instead of 1-150. So far it doesn't appear to be
73 * a problem.
74 */
75 static inline bool
uint_key_compare(const void * a,const void * b)76 uint_key_compare(const void *a, const void *b)
77 {
78 return a == b;
79 }
80
81 static inline uint32_t
uint_hash(GLuint id)82 uint_hash(GLuint id)
83 {
84 return id;
85 }
86
87 static inline uint32_t
uint_key_hash(const void * key)88 uint_key_hash(const void *key)
89 {
90 return uint_hash((uintptr_t)key);
91 }
92
93 static inline void *
uint_key(GLuint id)94 uint_key(GLuint id)
95 {
96 return (void *)(uintptr_t) id;
97 }
98 /** @} */
99
100 /**
101 * The hash table data structure.
102 */
103 struct _mesa_HashTable {
104 struct hash_table *ht;
105 GLuint MaxKey; /**< highest key inserted so far */
106 mtx_t Mutex; /**< mutual exclusion lock */
107 GLboolean InDeleteAll; /**< Debug check */
108 /* Used when name reuse is enabled */
109 struct util_idalloc* id_alloc;
110
111 /** Value that would be in the table for DELETED_KEY_VALUE. */
112 void *deleted_key_data;
113 };
114
115 extern struct _mesa_HashTable *_mesa_NewHashTable(void);
116
117 extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
118
119 extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
120
121 extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data,
122 GLboolean isGenName);
123
124 extern void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key);
125
126 /**
127 * Lock the hash table mutex.
128 *
129 * This function should be used when multiple objects need
130 * to be looked up in the hash table, to avoid having to lock
131 * and unlock the mutex each time.
132 *
133 * \param table the hash table.
134 */
135 static inline void
_mesa_HashLockMutex(struct _mesa_HashTable * table)136 _mesa_HashLockMutex(struct _mesa_HashTable *table)
137 {
138 assert(table);
139 mtx_lock(&table->Mutex);
140 }
141
142
143 /**
144 * Unlock the hash table mutex.
145 *
146 * \param table the hash table.
147 */
148 static inline void
_mesa_HashUnlockMutex(struct _mesa_HashTable * table)149 _mesa_HashUnlockMutex(struct _mesa_HashTable *table)
150 {
151 assert(table);
152 mtx_unlock(&table->Mutex);
153 }
154
155 extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
156
157 extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
158 GLuint key, void *data, GLboolean isGenName);
159
160 extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
161
162 extern void
163 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
164 void (*callback)(void *data, void *userData),
165 void *userData);
166
167 extern void
168 _mesa_HashWalk(const struct _mesa_HashTable *table,
169 void (*callback)(void *data, void *userData),
170 void *userData);
171
172 extern void
173 _mesa_HashWalkLocked(const struct _mesa_HashTable *table,
174 void (*callback)(void *data, void *userData),
175 void *userData);
176
177 extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
178
179 extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
180
181 extern bool
182 _mesa_HashFindFreeKeys(struct _mesa_HashTable *table, GLuint* keys, GLuint numKeys);
183
184 extern GLuint
185 _mesa_HashNumEntries(const struct _mesa_HashTable *table);
186
187 extern void _mesa_test_hash_functions(void);
188
189 extern void _mesa_HashEnableNameReuse(struct _mesa_HashTable *table);
190
191
192 #endif
193