src/mesa/main/hash.h

   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
  74 uint_key_compare(const void *a, const void *b)
  75 {
  76    return a == b;
  77 }
  78
  79 static inline uint32_t
  80 uint_hash(GLuint id)
  81 {
  82    return id;
  83 }
  84
  85 static inline uint32_t
  86 uint_key_hash(const void *key)
  87 {
  88    return uint_hash((uintptr_t)key);
  89 }
  90
  91 static inline void *
  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
 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
 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