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1901 | serge | 1 | /** |
2 | * \file hash.c |
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3 | * Generic hash table. |
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4 | * |
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5 | * Used for display lists, texture objects, vertex/fragment programs, |
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6 | * buffer objects, etc. The hash functions are thread-safe. |
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7 | * |
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8 | * \note key=0 is illegal. |
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9 | * |
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10 | * \author Brian Paul |
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11 | */ |
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12 | |||
13 | /* |
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14 | * Mesa 3-D graphics library |
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15 | * Version: 6.5.1 |
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16 | * |
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17 | * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. |
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18 | * |
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19 | * Permission is hereby granted, free of charge, to any person obtaining a |
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20 | * copy of this software and associated documentation files (the "Software"), |
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21 | * to deal in the Software without restriction, including without limitation |
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22 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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23 | * and/or sell copies of the Software, and to permit persons to whom the |
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24 | * Software is furnished to do so, subject to the following conditions: |
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25 | * |
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26 | * The above copyright notice and this permission notice shall be included |
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27 | * in all copies or substantial portions of the Software. |
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28 | * |
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29 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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30 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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31 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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32 | * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
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33 | * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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34 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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35 | */ |
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36 | |||
37 | |||
38 | #include "glheader.h" |
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39 | #include "imports.h" |
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40 | #include "glapi/glthread.h" |
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41 | #include "hash.h" |
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42 | |||
43 | |||
44 | #define TABLE_SIZE 1023 /**< Size of lookup table/array */ |
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45 | |||
46 | #define HASH_FUNC(K) ((K) % TABLE_SIZE) |
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47 | |||
48 | |||
49 | /** |
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50 | * An entry in the hash table. |
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51 | */ |
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52 | struct HashEntry { |
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53 | GLuint Key; /**< the entry's key */ |
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54 | void *Data; /**< the entry's data */ |
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55 | struct HashEntry *Next; /**< pointer to next entry */ |
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56 | }; |
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57 | |||
58 | |||
59 | /** |
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60 | * The hash table data structure. |
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61 | */ |
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62 | struct _mesa_HashTable { |
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63 | struct HashEntry *Table[TABLE_SIZE]; /**< the lookup table */ |
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64 | GLuint MaxKey; /**< highest key inserted so far */ |
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65 | _glthread_Mutex Mutex; /**< mutual exclusion lock */ |
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66 | _glthread_Mutex WalkMutex; /**< for _mesa_HashWalk() */ |
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67 | GLboolean InDeleteAll; /**< Debug check */ |
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68 | }; |
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69 | |||
70 | |||
71 | |||
72 | /** |
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73 | * Create a new hash table. |
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74 | * |
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75 | * \return pointer to a new, empty hash table. |
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76 | */ |
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77 | struct _mesa_HashTable * |
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78 | _mesa_NewHashTable(void) |
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79 | { |
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80 | struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable); |
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81 | if (table) { |
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82 | _glthread_INIT_MUTEX(table->Mutex); |
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83 | _glthread_INIT_MUTEX(table->WalkMutex); |
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84 | } |
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85 | return table; |
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86 | } |
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87 | |||
88 | |||
89 | |||
90 | /** |
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91 | * Delete a hash table. |
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92 | * Frees each entry on the hash table and then the hash table structure itself. |
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93 | * Note that the caller should have already traversed the table and deleted |
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94 | * the objects in the table (i.e. We don't free the entries' data pointer). |
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95 | * |
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96 | * \param table the hash table to delete. |
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97 | */ |
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98 | void |
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99 | _mesa_DeleteHashTable(struct _mesa_HashTable *table) |
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100 | { |
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101 | GLuint pos; |
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102 | assert(table); |
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103 | for (pos = 0; pos < TABLE_SIZE; pos++) { |
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104 | struct HashEntry *entry = table->Table[pos]; |
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105 | while (entry) { |
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106 | struct HashEntry *next = entry->Next; |
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107 | if (entry->Data) { |
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108 | _mesa_problem(NULL, |
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109 | "In _mesa_DeleteHashTable, found non-freed data"); |
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110 | } |
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111 | free(entry); |
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112 | entry = next; |
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113 | } |
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114 | } |
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115 | _glthread_DESTROY_MUTEX(table->Mutex); |
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116 | _glthread_DESTROY_MUTEX(table->WalkMutex); |
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117 | free(table); |
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118 | } |
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119 | |||
120 | |||
121 | |||
122 | /** |
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123 | * Lookup an entry in the hash table, without locking. |
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124 | * \sa _mesa_HashLookup |
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125 | */ |
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126 | static INLINE void * |
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127 | _mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key) |
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128 | { |
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129 | GLuint pos; |
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130 | const struct HashEntry *entry; |
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131 | |||
132 | assert(table); |
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133 | assert(key); |
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134 | |||
135 | pos = HASH_FUNC(key); |
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136 | entry = table->Table[pos]; |
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137 | while (entry) { |
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138 | if (entry->Key == key) { |
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139 | return entry->Data; |
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140 | } |
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141 | entry = entry->Next; |
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142 | } |
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143 | return NULL; |
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144 | } |
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145 | |||
146 | |||
147 | /** |
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148 | * Lookup an entry in the hash table. |
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149 | * |
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150 | * \param table the hash table. |
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151 | * \param key the key. |
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152 | * |
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153 | * \return pointer to user's data or NULL if key not in table |
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154 | */ |
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155 | void * |
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156 | _mesa_HashLookup(struct _mesa_HashTable *table, GLuint key) |
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157 | { |
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158 | void *res; |
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159 | assert(table); |
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160 | _glthread_LOCK_MUTEX(table->Mutex); |
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161 | res = _mesa_HashLookup_unlocked(table, key); |
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162 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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163 | return res; |
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164 | } |
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165 | |||
166 | |||
167 | /** |
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168 | * Insert a key/pointer pair into the hash table. |
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169 | * If an entry with this key already exists we'll replace the existing entry. |
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170 | * |
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171 | * \param table the hash table. |
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172 | * \param key the key (not zero). |
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173 | * \param data pointer to user data. |
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174 | */ |
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175 | void |
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176 | _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data) |
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177 | { |
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178 | /* search for existing entry with this key */ |
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179 | GLuint pos; |
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180 | struct HashEntry *entry; |
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181 | |||
182 | assert(table); |
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183 | assert(key); |
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184 | |||
185 | _glthread_LOCK_MUTEX(table->Mutex); |
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186 | |||
187 | if (key > table->MaxKey) |
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188 | table->MaxKey = key; |
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189 | |||
190 | pos = HASH_FUNC(key); |
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191 | |||
192 | /* check if replacing an existing entry with same key */ |
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193 | for (entry = table->Table[pos]; entry; entry = entry->Next) { |
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194 | if (entry->Key == key) { |
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195 | /* replace entry's data */ |
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196 | #if 0 /* not sure this check is always valid */ |
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197 | if (entry->Data) { |
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198 | _mesa_problem(NULL, "Memory leak detected in _mesa_HashInsert"); |
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199 | } |
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200 | #endif |
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201 | entry->Data = data; |
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202 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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203 | return; |
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204 | } |
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205 | } |
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206 | |||
207 | /* alloc and insert new table entry */ |
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208 | entry = MALLOC_STRUCT(HashEntry); |
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209 | if (entry) { |
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210 | entry->Key = key; |
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211 | entry->Data = data; |
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212 | entry->Next = table->Table[pos]; |
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213 | table->Table[pos] = entry; |
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214 | } |
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215 | |||
216 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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217 | } |
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218 | |||
219 | |||
220 | |||
221 | /** |
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222 | * Remove an entry from the hash table. |
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223 | * |
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224 | * \param table the hash table. |
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225 | * \param key key of entry to remove. |
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226 | * |
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227 | * While holding the hash table's lock, searches the entry with the matching |
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228 | * key and unlinks it. |
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229 | */ |
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230 | void |
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231 | _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key) |
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232 | { |
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233 | GLuint pos; |
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234 | struct HashEntry *entry, *prev; |
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235 | |||
236 | assert(table); |
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237 | assert(key); |
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238 | |||
239 | /* have to check this outside of mutex lock */ |
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240 | if (table->InDeleteAll) { |
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241 | _mesa_problem(NULL, "_mesa_HashRemove illegally called from " |
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242 | "_mesa_HashDeleteAll callback function"); |
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243 | return; |
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244 | } |
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245 | |||
246 | _glthread_LOCK_MUTEX(table->Mutex); |
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247 | |||
248 | pos = HASH_FUNC(key); |
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249 | prev = NULL; |
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250 | entry = table->Table[pos]; |
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251 | while (entry) { |
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252 | if (entry->Key == key) { |
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253 | /* found it! */ |
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254 | if (prev) { |
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255 | prev->Next = entry->Next; |
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256 | } |
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257 | else { |
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258 | table->Table[pos] = entry->Next; |
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259 | } |
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260 | free(entry); |
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261 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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262 | return; |
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263 | } |
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264 | prev = entry; |
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265 | entry = entry->Next; |
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266 | } |
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267 | |||
268 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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269 | } |
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270 | |||
271 | |||
272 | |||
273 | /** |
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274 | * Delete all entries in a hash table, but don't delete the table itself. |
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275 | * Invoke the given callback function for each table entry. |
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276 | * |
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277 | * \param table the hash table to delete |
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278 | * \param callback the callback function |
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279 | * \param userData arbitrary pointer to pass along to the callback |
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280 | * (this is typically a struct gl_context pointer) |
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281 | */ |
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282 | void |
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283 | _mesa_HashDeleteAll(struct _mesa_HashTable *table, |
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284 | void (*callback)(GLuint key, void *data, void *userData), |
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285 | void *userData) |
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286 | { |
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287 | GLuint pos; |
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288 | ASSERT(table); |
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289 | ASSERT(callback); |
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290 | _glthread_LOCK_MUTEX(table->Mutex); |
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291 | table->InDeleteAll = GL_TRUE; |
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292 | for (pos = 0; pos < TABLE_SIZE; pos++) { |
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293 | struct HashEntry *entry, *next; |
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294 | for (entry = table->Table[pos]; entry; entry = next) { |
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295 | callback(entry->Key, entry->Data, userData); |
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296 | next = entry->Next; |
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297 | free(entry); |
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298 | } |
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299 | table->Table[pos] = NULL; |
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300 | } |
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301 | table->InDeleteAll = GL_FALSE; |
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302 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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303 | } |
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304 | |||
305 | |||
306 | /** |
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307 | * Walk over all entries in a hash table, calling callback function for each. |
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308 | * Note: we use a separate mutex in this function to avoid a recursive |
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309 | * locking deadlock (in case the callback calls _mesa_HashRemove()) and to |
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310 | * prevent multiple threads/contexts from getting tangled up. |
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311 | * A lock-less version of this function could be used when the table will |
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312 | * not be modified. |
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313 | * \param table the hash table to walk |
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314 | * \param callback the callback function |
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315 | * \param userData arbitrary pointer to pass along to the callback |
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316 | * (this is typically a struct gl_context pointer) |
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317 | */ |
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318 | void |
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319 | _mesa_HashWalk(const struct _mesa_HashTable *table, |
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320 | void (*callback)(GLuint key, void *data, void *userData), |
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321 | void *userData) |
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322 | { |
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323 | /* cast-away const */ |
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324 | struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table; |
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325 | GLuint pos; |
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326 | ASSERT(table); |
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327 | ASSERT(callback); |
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328 | _glthread_LOCK_MUTEX(table2->WalkMutex); |
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329 | for (pos = 0; pos < TABLE_SIZE; pos++) { |
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330 | struct HashEntry *entry, *next; |
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331 | for (entry = table->Table[pos]; entry; entry = next) { |
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332 | /* save 'next' pointer now in case the callback deletes the entry */ |
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333 | next = entry->Next; |
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334 | callback(entry->Key, entry->Data, userData); |
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335 | } |
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336 | } |
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337 | _glthread_UNLOCK_MUTEX(table2->WalkMutex); |
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338 | } |
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339 | |||
340 | |||
341 | /** |
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342 | * Return the key of the "first" entry in the hash table. |
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343 | * While holding the lock, walks through all table positions until finding |
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344 | * the first entry of the first non-empty one. |
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345 | * |
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346 | * \param table the hash table |
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347 | * \return key for the "first" entry in the hash table. |
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348 | */ |
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349 | GLuint |
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350 | _mesa_HashFirstEntry(struct _mesa_HashTable *table) |
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351 | { |
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352 | GLuint pos; |
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353 | assert(table); |
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354 | _glthread_LOCK_MUTEX(table->Mutex); |
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355 | for (pos = 0; pos < TABLE_SIZE; pos++) { |
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356 | if (table->Table[pos]) { |
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357 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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358 | return table->Table[pos]->Key; |
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359 | } |
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360 | } |
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361 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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362 | return 0; |
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363 | } |
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364 | |||
365 | |||
366 | /** |
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367 | * Given a hash table key, return the next key. This is used to walk |
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368 | * over all entries in the table. Note that the keys returned during |
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369 | * walking won't be in any particular order. |
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370 | * \return next hash key or 0 if end of table. |
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371 | */ |
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372 | GLuint |
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373 | _mesa_HashNextEntry(const struct _mesa_HashTable *table, GLuint key) |
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374 | { |
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375 | const struct HashEntry *entry; |
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376 | GLuint pos; |
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377 | |||
378 | assert(table); |
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379 | assert(key); |
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380 | |||
381 | /* Find the entry with given key */ |
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382 | pos = HASH_FUNC(key); |
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383 | for (entry = table->Table[pos]; entry ; entry = entry->Next) { |
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384 | if (entry->Key == key) { |
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385 | break; |
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386 | } |
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387 | } |
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388 | |||
389 | if (!entry) { |
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390 | /* the given key was not found, so we can't find the next entry */ |
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391 | return 0; |
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392 | } |
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393 | |||
394 | if (entry->Next) { |
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395 | /* return next in linked list */ |
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396 | return entry->Next->Key; |
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397 | } |
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398 | else { |
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399 | /* look for next non-empty table slot */ |
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400 | pos++; |
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401 | while (pos < TABLE_SIZE) { |
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402 | if (table->Table[pos]) { |
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403 | return table->Table[pos]->Key; |
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404 | } |
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405 | pos++; |
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406 | } |
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407 | return 0; |
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408 | } |
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409 | } |
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410 | |||
411 | |||
412 | /** |
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413 | * Dump contents of hash table for debugging. |
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414 | * |
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415 | * \param table the hash table. |
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416 | */ |
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417 | void |
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418 | _mesa_HashPrint(const struct _mesa_HashTable *table) |
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419 | { |
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420 | GLuint pos; |
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421 | assert(table); |
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422 | for (pos = 0; pos < TABLE_SIZE; pos++) { |
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423 | const struct HashEntry *entry = table->Table[pos]; |
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424 | while (entry) { |
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425 | _mesa_debug(NULL, "%u %p\n", entry->Key, entry->Data); |
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426 | entry = entry->Next; |
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427 | } |
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428 | } |
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429 | } |
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430 | |||
431 | |||
432 | |||
433 | /** |
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434 | * Find a block of adjacent unused hash keys. |
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435 | * |
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436 | * \param table the hash table. |
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437 | * \param numKeys number of keys needed. |
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438 | * |
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439 | * \return Starting key of free block or 0 if failure. |
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440 | * |
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441 | * If there are enough free keys between the maximum key existing in the table |
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442 | * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return |
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443 | * the adjacent key. Otherwise do a full search for a free key block in the |
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444 | * allowable key range. |
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445 | */ |
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446 | GLuint |
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447 | _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys) |
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448 | { |
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449 | const GLuint maxKey = ~((GLuint) 0); |
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450 | _glthread_LOCK_MUTEX(table->Mutex); |
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451 | if (maxKey - numKeys > table->MaxKey) { |
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452 | /* the quick solution */ |
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453 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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454 | return table->MaxKey + 1; |
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455 | } |
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456 | else { |
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457 | /* the slow solution */ |
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458 | GLuint freeCount = 0; |
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459 | GLuint freeStart = 1; |
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460 | GLuint key; |
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461 | for (key = 1; key != maxKey; key++) { |
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462 | if (_mesa_HashLookup_unlocked(table, key)) { |
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463 | /* darn, this key is already in use */ |
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464 | freeCount = 0; |
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465 | freeStart = key+1; |
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466 | } |
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467 | else { |
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468 | /* this key not in use, check if we've found enough */ |
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469 | freeCount++; |
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470 | if (freeCount == numKeys) { |
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471 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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472 | return freeStart; |
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473 | } |
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474 | } |
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475 | } |
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476 | /* cannot allocate a block of numKeys consecutive keys */ |
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477 | _glthread_UNLOCK_MUTEX(table->Mutex); |
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478 | return 0; |
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479 | } |
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480 | } |
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481 | |||
482 | |||
483 | #if 0 /* debug only */ |
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484 | |||
485 | /** |
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486 | * Test walking over all the entries in a hash table. |
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487 | */ |
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488 | static void |
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489 | test_hash_walking(void) |
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490 | { |
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491 | struct _mesa_HashTable *t = _mesa_NewHashTable(); |
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492 | const GLuint limit = 50000; |
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493 | GLuint i; |
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494 | |||
495 | /* create some entries */ |
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496 | for (i = 0; i < limit; i++) { |
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497 | GLuint dummy; |
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498 | GLuint k = (rand() % (limit * 10)) + 1; |
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499 | while (_mesa_HashLookup(t, k)) { |
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500 | /* id already in use, try another */ |
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501 | k = (rand() % (limit * 10)) + 1; |
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502 | } |
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503 | _mesa_HashInsert(t, k, &dummy); |
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504 | } |
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505 | |||
506 | /* walk over all entries */ |
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507 | { |
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508 | GLuint k = _mesa_HashFirstEntry(t); |
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509 | GLuint count = 0; |
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510 | while (k) { |
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511 | GLuint knext = _mesa_HashNextEntry(t, k); |
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512 | assert(knext != k); |
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513 | _mesa_HashRemove(t, k); |
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514 | count++; |
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515 | k = knext; |
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516 | } |
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517 | assert(count == limit); |
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518 | k = _mesa_HashFirstEntry(t); |
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519 | assert(k==0); |
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520 | } |
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521 | |||
522 | _mesa_DeleteHashTable(t); |
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523 | } |
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524 | |||
525 | |||
526 | void |
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527 | _mesa_test_hash_functions(void) |
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528 | { |
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529 | int a, b, c; |
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530 | struct _mesa_HashTable *t; |
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531 | |||
532 | t = _mesa_NewHashTable(); |
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533 | _mesa_HashInsert(t, 501, &a); |
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534 | _mesa_HashInsert(t, 10, &c); |
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535 | _mesa_HashInsert(t, 0xfffffff8, &b); |
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536 | /*_mesa_HashPrint(t);*/ |
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537 | |||
538 | assert(_mesa_HashLookup(t,501)); |
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539 | assert(!_mesa_HashLookup(t,1313)); |
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540 | assert(_mesa_HashFindFreeKeyBlock(t, 100)); |
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541 | |||
542 | _mesa_DeleteHashTable(t); |
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543 | |||
544 | test_hash_walking(); |
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545 | } |
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546 | |||
547 | #endif>>>>>>>>>>>>>>>> |