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 "util/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  */
  71 static inline bool
  72 uint_key_compare(const void *a, const void *b)
  73 {
  74    return a == b;
  75 }
  76
  77 static inline uint32_t
  78 uint_hash(GLuint id)
  79 {
  80    return id;
  81 }
  82
  83 static inline uint32_t
  84 uint_key_hash(const void *key)
  85 {
  86    return uint_hash((uintptr_t)key);
  87 }
  88
  89 static inline void *
  90 uint_key(GLuint id)
  91 {
  92    return (void *)(uintptr_t) id;
  93 }
  94 /** @} */
  95
  96 /**
  97  * The hash table data structure.
  98  */
  99 struct _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
 108 extern struct _mesa_HashTable *_mesa_NewHashTable(void);
 109
 110 extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
 111
 112 extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
 113
 114 extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data);
 115
 116 extern 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  */
 127 static 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  */
 140 static inline void
 141 _mesa_HashUnlockMutex(struct _mesa_HashTable *table)
 142 {
 143    assert(table);
 144    mtx_unlock(&table->Mutex);
 145 }
 146
 147 extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
 148
 149 extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
 150                                    GLuint key, void *data);
 151
 152 extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
 153
 154 extern void
 155 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
 156                     void (*callback)(GLuint key, void *data, void *userData),
 157                     void *userData);
 158
 159 extern void
 160 _mesa_HashWalk(const struct _mesa_HashTable *table,
 161                void (*callback)(GLuint key, void *data, void *userData),
 162                void *userData);
 163
 164 extern void
 165 _mesa_HashWalkLocked(const struct _mesa_HashTable *table,
 166                      void (*callback)(GLuint key, void *data, void *userData),
 167                      void *userData);
 168
 169 extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
 170
 171 extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
 172
 173 extern GLuint
 174 _mesa_HashNumEntries(const struct _mesa_HashTable *table);
 175
 176 extern void _mesa_test_hash_functions(void);
 177
 178
 179 #endif