hash.h revision b8e80941 
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#include "c11/threads.h"
38
39/**
40 * Magic GLuint object name that gets stored outside of the struct hash_table.
41 *
42 * The hash table needs a particular pointer to be the marker for a key that
43 * was deleted from the table, along with NULL for the "never allocated in the
44 * table" marker.  Legacy GL allows any GLuint to be used as a GL object name,
45 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be
46 * able to track a GLuint that happens to match the deleted key outside of
47 * struct hash_table.  We tell the hash table to use "1" as the deleted key
48 * value, so that we test the deleted-key-in-the-table path as best we can.
49 */
50#define DELETED_KEY_VALUE 1
51
52/** @{
53 * Mapping from our use of GLuint as both the key and the hash value to the
54 * hash_table.h API
55 *
56 * There exist many integer hash functions, designed to avoid collisions when
57 * the integers are spread across key space with some patterns.  In GL, the
58 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
59 * contiguous integers starting from 1.  Because of that, we just use the key
60 * as the hash value, to minimize the cost of the hash function.  If objects
61 * are never deleted, we will never see a collision in the table, because the
62 * table resizes itself when it approaches full, and thus key % table_size ==
63 * key.
64 *
65 * The case where we could have collisions for genned objects would be
66 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
67 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
68 * the end of that sequence, instead of 1-150.  So far it doesn't appear to be
69 * a problem.
70 */
71static inline bool
72uint_key_compare(const void *a, const void *b)
73{
74   return a == b;
75}
76
77static inline uint32_t
78uint_hash(GLuint id)
79{
80   return id;
81}
82
83static inline uint32_t
84uint_key_hash(const void *key)
85{
86   return uint_hash((uintptr_t)key);
87}
88
89static inline void *
90uint_key(GLuint id)
91{
92   return (void *)(uintptr_t) id;
93}
94/** @} */
95
96/**
97 * The hash table data structure.
98 */
99struct _mesa_HashTable {
100   struct hash_table *ht;
101   GLuint MaxKey;                        /**< highest key inserted so far */
102   mtx_t Mutex;                          /**< mutual exclusion lock */
103   GLboolean InDeleteAll;                /**< Debug check */
104   /** Value that would be in the table for DELETED_KEY_VALUE. */
105   void *deleted_key_data;
106};
107
108extern struct _mesa_HashTable *_mesa_NewHashTable(void);
109
110extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
111
112extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
113
114extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data);
115
116extern void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key);
117
118/**
119 * Lock the hash table mutex.
120 *
121 * This function should be used when multiple objects need
122 * to be looked up in the hash table, to avoid having to lock
123 * and unlock the mutex each time.
124 *
125 * \param table the hash table.
126 */
127static inline void
128_mesa_HashLockMutex(struct _mesa_HashTable *table)
129{
130   assert(table);
131   mtx_lock(&table->Mutex);
132}
133
134
135/**
136 * Unlock the hash table mutex.
137 *
138 * \param table the hash table.
139 */
140static inline void
141_mesa_HashUnlockMutex(struct _mesa_HashTable *table)
142{
143   assert(table);
144   mtx_unlock(&table->Mutex);
145}
146
147extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
148
149extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
150                                   GLuint key, void *data);
151
152extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
153
154extern void
155_mesa_HashDeleteAll(struct _mesa_HashTable *table,
156                    void (*callback)(GLuint key, void *data, void *userData),
157                    void *userData);
158
159extern void
160_mesa_HashWalk(const struct _mesa_HashTable *table,
161               void (*callback)(GLuint key, void *data, void *userData),
162               void *userData);
163
164extern void
165_mesa_HashWalkLocked(const struct _mesa_HashTable *table,
166                     void (*callback)(GLuint key, void *data, void *userData),
167                     void *userData);
168
169extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
170
171extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
172
173extern GLuint
174_mesa_HashNumEntries(const struct _mesa_HashTable *table);
175
176extern void _mesa_test_hash_functions(void);
177
178
179#endif
180