1 /** 2 * \file hash.c 3 * Generic hash table. 4 * 5 * Used for display lists, texture objects, vertex/fragment programs, 6 * buffer objects, etc. The hash functions are thread-safe. 7 * 8 * \note key=0 is illegal. 9 * 10 * \author Brian Paul 11 */ 12 13 /* 14 * Mesa 3-D graphics library 15 * 16 * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. 17 * 18 * Permission is hereby granted, free of charge, to any person obtaining a 19 * copy of this software and associated documentation files (the "Software"), 20 * to deal in the Software without restriction, including without limitation 21 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 22 * and/or sell copies of the Software, and to permit persons to whom the 23 * Software is furnished to do so, subject to the following conditions: 24 * 25 * The above copyright notice and this permission notice shall be included 26 * in all copies or substantial portions of the Software. 27 * 28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 29 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 31 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 32 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 33 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 34 * OTHER DEALINGS IN THE SOFTWARE. 35 */ 36 37 #include "glheader.h" 38 #include "imports.h" 39 #include "hash.h" 40 #include "util/hash_table.h" 41 42 /** 43 * Magic GLuint object name that gets stored outside of the struct hash_table. 44 * 45 * The hash table needs a particular pointer to be the marker for a key that 46 * was deleted from the table, along with NULL for the "never allocated in the 47 * table" marker. Legacy GL allows any GLuint to be used as a GL object name, 48 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be 49 * able to track a GLuint that happens to match the deleted key outside of 50 * struct hash_table. We tell the hash table to use "1" as the deleted key 51 * value, so that we test the deleted-key-in-the-table path as best we can. 52 */ 53 #define DELETED_KEY_VALUE 1 54 55 /** 56 * The hash table data structure. 57 */ 58 struct _mesa_HashTable { 59 struct hash_table *ht; 60 GLuint MaxKey; /**< highest key inserted so far */ 61 mtx_t Mutex; /**< mutual exclusion lock */ 62 GLboolean InDeleteAll; /**< Debug check */ 63 /** Value that would be in the table for DELETED_KEY_VALUE. */ 64 void *deleted_key_data; 65 }; 66 67 /** @{ 68 * Mapping from our use of GLuint as both the key and the hash value to the 69 * hash_table.h API 70 * 71 * There exist many integer hash functions, designed to avoid collisions when 72 * the integers are spread across key space with some patterns. In GL, the 73 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique 74 * contiguous integers starting from 1. Because of that, we just use the key 75 * as the hash value, to minimize the cost of the hash function. If objects 76 * are never deleted, we will never see a collision in the table, because the 77 * table resizes itself when it approaches full, and thus key % table_size == 78 * key. 79 * 80 * The case where we could have collisions for genned objects would be 81 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50); 82 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at 83 * the end of that sequence, instead of 1-150. So far it doesn't appear to be 84 * a problem. 85 */ 86 static bool 87 uint_key_compare(const void *a, const void *b) 88 { 89 return a == b; 90 } 91 92 static uint32_t 93 uint_hash(GLuint id) 94 { 95 return id; 96 } 97 98 static uint32_t 99 uint_key_hash(const void *key) 100 { 101 return uint_hash((uintptr_t)key); 102 } 103 104 static void * 105 uint_key(GLuint id) 106 { 107 return (void *)(uintptr_t) id; 108 } 109 /** @} */ 110 111 /** 112 * Create a new hash table. 113 * 114 * \return pointer to a new, empty hash table. 115 */ 116 struct _mesa_HashTable * 117 _mesa_NewHashTable(void) 118 { 119 struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable); 120 121 if (table) { 122 table->ht = _mesa_hash_table_create(NULL, uint_key_hash, 123 uint_key_compare); 124 if (table->ht == NULL) { 125 free(table); 126 _mesa_error_no_memory(__func__); 127 return NULL; 128 } 129 130 _mesa_hash_table_set_deleted_key(table->ht, uint_key(DELETED_KEY_VALUE)); 131 /* 132 * Needs to be recursive, since the callback in _mesa_HashWalk() 133 * is allowed to call _mesa_HashRemove(). 134 */ 135 mtx_init(&table->Mutex, mtx_recursive); 136 } 137 else { 138 _mesa_error_no_memory(__func__); 139 } 140 141 return table; 142 } 143 144 145 146 /** 147 * Delete a hash table. 148 * Frees each entry on the hash table and then the hash table structure itself. 149 * Note that the caller should have already traversed the table and deleted 150 * the objects in the table (i.e. We don't free the entries' data pointer). 151 * 152 * \param table the hash table to delete. 153 */ 154 void 155 _mesa_DeleteHashTable(struct _mesa_HashTable *table) 156 { 157 assert(table); 158 159 if (_mesa_hash_table_next_entry(table->ht, NULL) != NULL) { 160 _mesa_problem(NULL, "In _mesa_DeleteHashTable, found non-freed data"); 161 } 162 163 _mesa_hash_table_destroy(table->ht, NULL); 164 165 mtx_destroy(&table->Mutex); 166 free(table); 167 } 168 169 170 171 /** 172 * Lookup an entry in the hash table, without locking. 173 * \sa _mesa_HashLookup 174 */ 175 static inline void * 176 _mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key) 177 { 178 const struct hash_entry *entry; 179 180 assert(table); 181 assert(key); 182 183 if (key == DELETED_KEY_VALUE) 184 return table->deleted_key_data; 185 186 entry = _mesa_hash_table_search(table->ht, uint_key(key)); 187 if (!entry) 188 return NULL; 189 190 return entry->data; 191 } 192 193 194 /** 195 * Lookup an entry in the hash table. 196 * 197 * \param table the hash table. 198 * \param key the key. 199 * 200 * \return pointer to user's data or NULL if key not in table 201 */ 202 void * 203 _mesa_HashLookup(struct _mesa_HashTable *table, GLuint key) 204 { 205 void *res; 206 assert(table); 207 mtx_lock(&table->Mutex); 208 res = _mesa_HashLookup_unlocked(table, key); 209 mtx_unlock(&table->Mutex); 210 return res; 211 } 212 213 214 /** 215 * Lookup an entry in the hash table without locking the mutex. 216 * 217 * The hash table mutex must be locked manually by calling 218 * _mesa_HashLockMutex() before calling this function. 219 * 220 * \param table the hash table. 221 * \param key the key. 222 * 223 * \return pointer to user's data or NULL if key not in table 224 */ 225 void * 226 _mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key) 227 { 228 return _mesa_HashLookup_unlocked(table, key); 229 } 230 231 232 /** 233 * Lock the hash table mutex. 234 * 235 * This function should be used when multiple objects need 236 * to be looked up in the hash table, to avoid having to lock 237 * and unlock the mutex each time. 238 * 239 * \param table the hash table. 240 */ 241 void 242 _mesa_HashLockMutex(struct _mesa_HashTable *table) 243 { 244 assert(table); 245 mtx_lock(&table->Mutex); 246 } 247 248 249 /** 250 * Unlock the hash table mutex. 251 * 252 * \param table the hash table. 253 */ 254 void 255 _mesa_HashUnlockMutex(struct _mesa_HashTable *table) 256 { 257 assert(table); 258 mtx_unlock(&table->Mutex); 259 } 260 261 262 static inline void 263 _mesa_HashInsert_unlocked(struct _mesa_HashTable *table, GLuint key, void *data) 264 { 265 uint32_t hash = uint_hash(key); 266 struct hash_entry *entry; 267 268 assert(table); 269 assert(key); 270 271 if (key > table->MaxKey) 272 table->MaxKey = key; 273 274 if (key == DELETED_KEY_VALUE) { 275 table->deleted_key_data = data; 276 } else { 277 entry = _mesa_hash_table_search_pre_hashed(table->ht, hash, uint_key(key)); 278 if (entry) { 279 entry->data = data; 280 } else { 281 _mesa_hash_table_insert_pre_hashed(table->ht, hash, uint_key(key), data); 282 } 283 } 284 } 285 286 287 /** 288 * Insert a key/pointer pair into the hash table without locking the mutex. 289 * If an entry with this key already exists we'll replace the existing entry. 290 * 291 * The hash table mutex must be locked manually by calling 292 * _mesa_HashLockMutex() before calling this function. 293 * 294 * \param table the hash table. 295 * \param key the key (not zero). 296 * \param data pointer to user data. 297 */ 298 void 299 _mesa_HashInsertLocked(struct _mesa_HashTable *table, GLuint key, void *data) 300 { 301 _mesa_HashInsert_unlocked(table, key, data); 302 } 303 304 305 /** 306 * Insert a key/pointer pair into the hash table. 307 * If an entry with this key already exists we'll replace the existing entry. 308 * 309 * \param table the hash table. 310 * \param key the key (not zero). 311 * \param data pointer to user data. 312 */ 313 void 314 _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data) 315 { 316 assert(table); 317 mtx_lock(&table->Mutex); 318 _mesa_HashInsert_unlocked(table, key, data); 319 mtx_unlock(&table->Mutex); 320 } 321 322 323 /** 324 * Remove an entry from the hash table. 325 * 326 * \param table the hash table. 327 * \param key key of entry to remove. 328 * 329 * While holding the hash table's lock, searches the entry with the matching 330 * key and unlinks it. 331 */ 332 static inline void 333 _mesa_HashRemove_unlocked(struct _mesa_HashTable *table, GLuint key) 334 { 335 struct hash_entry *entry; 336 337 assert(table); 338 assert(key); 339 340 /* have to check this outside of mutex lock */ 341 if (table->InDeleteAll) { 342 _mesa_problem(NULL, "_mesa_HashRemove illegally called from " 343 "_mesa_HashDeleteAll callback function"); 344 return; 345 } 346 347 if (key == DELETED_KEY_VALUE) { 348 table->deleted_key_data = NULL; 349 } else { 350 entry = _mesa_hash_table_search(table->ht, uint_key(key)); 351 _mesa_hash_table_remove(table->ht, entry); 352 } 353 } 354 355 356 void 357 _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key) 358 { 359 _mesa_HashRemove_unlocked(table, key); 360 } 361 362 void 363 _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key) 364 { 365 mtx_lock(&table->Mutex); 366 _mesa_HashRemove_unlocked(table, key); 367 mtx_unlock(&table->Mutex); 368 } 369 370 /** 371 * Delete all entries in a hash table, but don't delete the table itself. 372 * Invoke the given callback function for each table entry. 373 * 374 * \param table the hash table to delete 375 * \param callback the callback function 376 * \param userData arbitrary pointer to pass along to the callback 377 * (this is typically a struct gl_context pointer) 378 */ 379 void 380 _mesa_HashDeleteAll(struct _mesa_HashTable *table, 381 void (*callback)(GLuint key, void *data, void *userData), 382 void *userData) 383 { 384 struct hash_entry *entry; 385 386 assert(table); 387 assert(callback); 388 mtx_lock(&table->Mutex); 389 table->InDeleteAll = GL_TRUE; 390 hash_table_foreach(table->ht, entry) { 391 callback((uintptr_t)entry->key, entry->data, userData); 392 _mesa_hash_table_remove(table->ht, entry); 393 } 394 if (table->deleted_key_data) { 395 callback(DELETED_KEY_VALUE, table->deleted_key_data, userData); 396 table->deleted_key_data = NULL; 397 } 398 table->InDeleteAll = GL_FALSE; 399 mtx_unlock(&table->Mutex); 400 } 401 402 403 /** 404 * Walk over all entries in a hash table, calling callback function for each. 405 * \param table the hash table to walk 406 * \param callback the callback function 407 * \param userData arbitrary pointer to pass along to the callback 408 * (this is typically a struct gl_context pointer) 409 */ 410 void 411 _mesa_HashWalk(const struct _mesa_HashTable *table, 412 void (*callback)(GLuint key, void *data, void *userData), 413 void *userData) 414 { 415 /* cast-away const */ 416 struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table; 417 struct hash_entry *entry; 418 419 assert(table); 420 assert(callback); 421 mtx_lock(&table2->Mutex); 422 hash_table_foreach(table->ht, entry) { 423 callback((uintptr_t)entry->key, entry->data, userData); 424 } 425 if (table->deleted_key_data) 426 callback(DELETED_KEY_VALUE, table->deleted_key_data, userData); 427 mtx_unlock(&table2->Mutex); 428 } 429 430 static void 431 debug_print_entry(GLuint key, void *data, void *userData) 432 { 433 _mesa_debug(NULL, "%u %p\n", key, data); 434 } 435 436 /** 437 * Dump contents of hash table for debugging. 438 * 439 * \param table the hash table. 440 */ 441 void 442 _mesa_HashPrint(const struct _mesa_HashTable *table) 443 { 444 if (table->deleted_key_data) 445 debug_print_entry(DELETED_KEY_VALUE, table->deleted_key_data, NULL); 446 _mesa_HashWalk(table, debug_print_entry, NULL); 447 } 448 449 450 /** 451 * Find a block of adjacent unused hash keys. 452 * 453 * \param table the hash table. 454 * \param numKeys number of keys needed. 455 * 456 * \return Starting key of free block or 0 if failure. 457 * 458 * If there are enough free keys between the maximum key existing in the table 459 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return 460 * the adjacent key. Otherwise do a full search for a free key block in the 461 * allowable key range. 462 */ 463 GLuint 464 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys) 465 { 466 const GLuint maxKey = ~((GLuint) 0) - 1; 467 if (maxKey - numKeys > table->MaxKey) { 468 /* the quick solution */ 469 return table->MaxKey + 1; 470 } 471 else { 472 /* the slow solution */ 473 GLuint freeCount = 0; 474 GLuint freeStart = 1; 475 GLuint key; 476 for (key = 1; key != maxKey; key++) { 477 if (_mesa_HashLookup_unlocked(table, key)) { 478 /* darn, this key is already in use */ 479 freeCount = 0; 480 freeStart = key+1; 481 } 482 else { 483 /* this key not in use, check if we've found enough */ 484 freeCount++; 485 if (freeCount == numKeys) { 486 return freeStart; 487 } 488 } 489 } 490 /* cannot allocate a block of numKeys consecutive keys */ 491 return 0; 492 } 493 } 494 495 496 /** 497 * Return the number of entries in the hash table. 498 */ 499 GLuint 500 _mesa_HashNumEntries(const struct _mesa_HashTable *table) 501 { 502 GLuint count = 0; 503 504 if (table->deleted_key_data) 505 count++; 506 507 count += _mesa_hash_table_num_entries(table->ht); 508 509 return count; 510 } 511