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 /**
42 * Magic GLuint object name that gets stored outside of the struct hash_table.
43 *
44 * The hash table needs a particular pointer to be the marker for a key that
45 * was deleted from the table, along with NULL for the "never allocated in the
46 * table" marker. Legacy GL allows any GLuint to be used as a GL object name,
47 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be
48 * able to track a GLuint that happens to match the deleted key outside of
49 * struct hash_table. We tell the hash table to use "1" as the deleted key
50 * value, so that we test the deleted-key-in-the-table path as best we can.
51 */
52 #define DELETED_KEY_VALUE 1
53
54 /** @{
55 * Mapping from our use of GLuint as both the key and the hash value to the
56 * hash_table.h API
57 *
58 * There exist many integer hash functions, designed to avoid collisions when
59 * the integers are spread across key space with some patterns. In GL, the
60 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
61 * contiguous integers starting from 1. Because of that, we just use the key
62 * as the hash value, to minimize the cost of the hash function. If objects
63 * are never deleted, we will never see a collision in the table, because the
64 * table resizes itself when it approaches full, and thus key % table_size ==
65 * key.
66 *
67 * The case where we could have collisions for genned objects would be
68 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
69 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
70 * the end of that sequence, instead of 1-150. So far it doesn't appear to be
71 * a problem.
72 */
73 static inline bool
uint_key_compare(const void * a,const void * b)74 uint_key_compare(const void *a, const void *b)
75 {
76 return a == b;
77 }
78
79 static inline uint32_t
uint_hash(GLuint id)80 uint_hash(GLuint id)
81 {
82 return id;
83 }
84
85 static inline uint32_t
uint_key_hash(const void * key)86 uint_key_hash(const void *key)
87 {
88 return uint_hash((uintptr_t)key);
89 }
90
91 static inline void *
uint_key(GLuint id)92 uint_key(GLuint id)
93 {
94 return (void *)(uintptr_t) id;
95 }
96 /** @} */
97
98 /**
99 * The hash table data structure.
100 */
101 struct _mesa_HashTable {
102 struct hash_table *ht;
103 GLuint MaxKey; /**< highest key inserted so far */
104 mtx_t Mutex; /**< mutual exclusion lock */
105 GLboolean InDeleteAll; /**< Debug check */
106 /** Value that would be in the table for DELETED_KEY_VALUE. */
107 void *deleted_key_data;
108 };
109
110 extern struct _mesa_HashTable *_mesa_NewHashTable(void);
111
112 extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
113
114 extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
115
116 extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data);
117
118 extern void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key);
119
120 /**
121 * Lock the hash table mutex.
122 *
123 * This function should be used when multiple objects need
124 * to be looked up in the hash table, to avoid having to lock
125 * and unlock the mutex each time.
126 *
127 * \param table the hash table.
128 */
129 static inline void
_mesa_HashLockMutex(struct _mesa_HashTable * table)130 _mesa_HashLockMutex(struct _mesa_HashTable *table)
131 {
132 assert(table);
133 mtx_lock(&table->Mutex);
134 }
135
136
137 /**
138 * Unlock the hash table mutex.
139 *
140 * \param table the hash table.
141 */
142 static inline void
_mesa_HashUnlockMutex(struct _mesa_HashTable * table)143 _mesa_HashUnlockMutex(struct _mesa_HashTable *table)
144 {
145 assert(table);
146 mtx_unlock(&table->Mutex);
147 }
148
149 extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
150
151 extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
152 GLuint key, void *data);
153
154 extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
155
156 extern void
157 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
158 void (*callback)(GLuint key, void *data, void *userData),
159 void *userData);
160
161 extern void
162 _mesa_HashWalk(const struct _mesa_HashTable *table,
163 void (*callback)(GLuint key, void *data, void *userData),
164 void *userData);
165
166 extern void
167 _mesa_HashWalkLocked(const struct _mesa_HashTable *table,
168 void (*callback)(GLuint key, void *data, void *userData),
169 void *userData);
170
171 extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
172
173 extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
174
175 extern GLuint
176 _mesa_HashNumEntries(const struct _mesa_HashTable *table);
177
178 extern void _mesa_test_hash_functions(void);
179
180
181 #endif
182