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 "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
  71 uint_key_compare(const void *a, const void *b)
  72 {
  73    return a == b;
  74 }
  75
  76 static inline uint32_t
  77 uint_hash(GLuint id)
  78 {
  79    return id;
  80 }
  81
  82 static inline uint32_t
  83 uint_key_hash(const void *key)
  84 {
  85    return uint_hash((uintptr_t)key);
  86 }
  87
  88 static inline void *
  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
 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
 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