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 "glheader.h"
36 #include "imports.h"
37
38 /**
39 * Magic GLuint object name that gets stored outside of the struct hash_table.
40 *
41 * The hash table needs a particular pointer to be the marker for a key that
42 * was deleted from the table, along with NULL for the "never allocated in the
43 * table" marker. Legacy GL allows any GLuint to be used as a GL object name,
44 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be
45 * able to track a GLuint that happens to match the deleted key outside of
46 * struct hash_table. We tell the hash table to use "1" as the deleted key
47 * value, so that we test the deleted-key-in-the-table path as best we can.
48 */
49 #define DELETED_KEY_VALUE 1
50
51 /** @{
52 * Mapping from our use of GLuint as both the key and the hash value to the
53 * hash_table.h API
54 *
55 * There exist many integer hash functions, designed to avoid collisions when
56 * the integers are spread across key space with some patterns. In GL, the
57 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
58 * contiguous integers starting from 1. Because of that, we just use the key
59 * as the hash value, to minimize the cost of the hash function. If objects
60 * are never deleted, we will never see a collision in the table, because the
61 * table resizes itself when it approaches full, and thus key % table_size ==
62 * key.
63 *
64 * The case where we could have collisions for genned objects would be
65 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
66 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
67 * the end of that sequence, instead of 1-150. So far it doesn't appear to be
68 * a problem.
69 */
70 static inline bool
uint_key_compare(const void * a,const void * b)71 uint_key_compare(const void *a, const void *b)
72 {
73 return a == b;
74 }
75
76 static inline uint32_t
uint_hash(GLuint id)77 uint_hash(GLuint id)
78 {
79 return id;
80 }
81
82 static inline uint32_t
uint_key_hash(const void * key)83 uint_key_hash(const void *key)
84 {
85 return uint_hash((uintptr_t)key);
86 }
87
88 static inline void *
uint_key(GLuint id)89 uint_key(GLuint id)
90 {
91 return (void *)(uintptr_t) id;
92 }
93 /** @} */
94
95 /**
96 * The hash table data structure.
97 */
98 struct _mesa_HashTable {
99 struct hash_table *ht;
100 GLuint MaxKey; /**< highest key inserted so far */
101 mtx_t Mutex; /**< mutual exclusion lock */
102 GLboolean InDeleteAll; /**< Debug check */
103 /** Value that would be in the table for DELETED_KEY_VALUE. */
104 void *deleted_key_data;
105 };
106
107 extern struct _mesa_HashTable *_mesa_NewHashTable(void);
108
109 extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
110
111 extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
112
113 extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data);
114
115 extern void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key);
116
117 /**
118 * Lock the hash table mutex.
119 *
120 * This function should be used when multiple objects need
121 * to be looked up in the hash table, to avoid having to lock
122 * and unlock the mutex each time.
123 *
124 * \param table the hash table.
125 */
126 static inline void
_mesa_HashLockMutex(struct _mesa_HashTable * table)127 _mesa_HashLockMutex(struct _mesa_HashTable *table)
128 {
129 assert(table);
130 mtx_lock(&table->Mutex);
131 }
132
133
134 /**
135 * Unlock the hash table mutex.
136 *
137 * \param table the hash table.
138 */
139 static inline void
_mesa_HashUnlockMutex(struct _mesa_HashTable * table)140 _mesa_HashUnlockMutex(struct _mesa_HashTable *table)
141 {
142 assert(table);
143 mtx_unlock(&table->Mutex);
144 }
145
146 extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
147
148 extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
149 GLuint key, void *data);
150
151 extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
152
153 extern void
154 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
155 void (*callback)(GLuint key, void *data, void *userData),
156 void *userData);
157
158 extern void
159 _mesa_HashWalk(const struct _mesa_HashTable *table,
160 void (*callback)(GLuint key, void *data, void *userData),
161 void *userData);
162
163 extern void
164 _mesa_HashWalkLocked(const struct _mesa_HashTable *table,
165 void (*callback)(GLuint key, void *data, void *userData),
166 void *userData);
167
168 extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
169
170 extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
171
172 extern GLuint
173 _mesa_HashNumEntries(const struct _mesa_HashTable *table);
174
175 extern void _mesa_test_hash_functions(void);
176
177
178 #endif
179