src/mesa/main/hash.c

   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_pre_hashed(table->ht,
 187                                               uint_hash(key),
 188                                               uint_key(key));
 189    if (!entry)
 190       return NULL;
 191
 192    return entry->data;
 193 }
 194
 195
 196 /**
 197  * Lookup an entry in the hash table.
 198  *
 199  * \param table the hash table.
 200  * \param key the key.
 201  *
 202  * \return pointer to user's data or NULL if key not in table
 203  */
 204 void *
 205 _mesa_HashLookup(struct _mesa_HashTable *table, GLuint key)
 206 {
 207    void *res;
 208    assert(table);
 209    mtx_lock(&table->Mutex);
 210    res = _mesa_HashLookup_unlocked(table, key);
 211    mtx_unlock(&table->Mutex);
 212    return res;
 213 }
 214
 215
 216 /**
 217  * Lookup an entry in the hash table without locking the mutex.
 218  *
 219  * The hash table mutex must be locked manually by calling
 220  * _mesa_HashLockMutex() before calling this function.
 221  *
 222  * \param table the hash table.
 223  * \param key the key.
 224  *
 225  * \return pointer to user's data or NULL if key not in table
 226  */
 227 void *
 228 _mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key)
 229 {
 230    return _mesa_HashLookup_unlocked(table, key);
 231 }
 232
 233
 234 /**
 235  * Lock the hash table mutex.
 236  *
 237  * This function should be used when multiple objects need
 238  * to be looked up in the hash table, to avoid having to lock
 239  * and unlock the mutex each time.
 240  *
 241  * \param table the hash table.
 242  */
 243 void
 244 _mesa_HashLockMutex(struct _mesa_HashTable *table)
 245 {
 246    assert(table);
 247    mtx_lock(&table->Mutex);
 248 }
 249
 250
 251 /**
 252  * Unlock the hash table mutex.
 253  *
 254  * \param table the hash table.
 255  */
 256 void
 257 _mesa_HashUnlockMutex(struct _mesa_HashTable *table)
 258 {
 259    assert(table);
 260    mtx_unlock(&table->Mutex);
 261 }
 262
 263
 264 static inline void
 265 _mesa_HashInsert_unlocked(struct _mesa_HashTable *table, GLuint key, void *data)
 266 {
 267    uint32_t hash = uint_hash(key);
 268    struct hash_entry *entry;
 269
 270    assert(table);
 271    assert(key);
 272
 273    if (key > table->MaxKey)
 274       table->MaxKey = key;
 275
 276    if (key == DELETED_KEY_VALUE) {
 277       table->deleted_key_data = data;
 278    } else {
 279       entry = _mesa_hash_table_search_pre_hashed(table->ht, hash, uint_key(key));
 280       if (entry) {
 281          entry->data = data;
 282       } else {
 283          _mesa_hash_table_insert_pre_hashed(table->ht, hash, uint_key(key), data);
 284       }
 285    }
 286 }
 287
 288
 289 /**
 290  * Insert a key/pointer pair into the hash table without locking the mutex.
 291  * If an entry with this key already exists we'll replace the existing entry.
 292  *
 293  * The hash table mutex must be locked manually by calling
 294  * _mesa_HashLockMutex() before calling this function.
 295  *
 296  * \param table the hash table.
 297  * \param key the key (not zero).
 298  * \param data pointer to user data.
 299  */
 300 void
 301 _mesa_HashInsertLocked(struct _mesa_HashTable *table, GLuint key, void *data)
 302 {
 303    _mesa_HashInsert_unlocked(table, key, data);
 304 }
 305
 306
 307 /**
 308  * Insert a key/pointer pair into the hash table.
 309  * If an entry with this key already exists we'll replace the existing entry.
 310  *
 311  * \param table the hash table.
 312  * \param key the key (not zero).
 313  * \param data pointer to user data.
 314  */
 315 void
 316 _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data)
 317 {
 318    assert(table);
 319    mtx_lock(&table->Mutex);
 320    _mesa_HashInsert_unlocked(table, key, data);
 321    mtx_unlock(&table->Mutex);
 322 }
 323
 324
 325 /**
 326  * Remove an entry from the hash table.
 327  *
 328  * \param table the hash table.
 329  * \param key key of entry to remove.
 330  *
 331  * While holding the hash table's lock, searches the entry with the matching
 332  * key and unlinks it.
 333  */
 334 static inline void
 335 _mesa_HashRemove_unlocked(struct _mesa_HashTable *table, GLuint key)
 336 {
 337    struct hash_entry *entry;
 338
 339    assert(table);
 340    assert(key);
 341
 342    /* have to check this outside of mutex lock */
 343    if (table->InDeleteAll) {
 344       _mesa_problem(NULL, "_mesa_HashRemove illegally called from "
 345                     "_mesa_HashDeleteAll callback function");
 346       return;
 347    }
 348
 349    if (key == DELETED_KEY_VALUE) {
 350       table->deleted_key_data = NULL;
 351    } else {
 352       entry = _mesa_hash_table_search_pre_hashed(table->ht,
 353                                                  uint_hash(key),
 354                                                  uint_key(key));
 355       _mesa_hash_table_remove(table->ht, entry);
 356    }
 357 }
 358
 359
 360 void
 361 _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key)
 362 {
 363    _mesa_HashRemove_unlocked(table, key);
 364 }
 365
 366 void
 367 _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)
 368 {
 369    mtx_lock(&table->Mutex);
 370    _mesa_HashRemove_unlocked(table, key);
 371    mtx_unlock(&table->Mutex);
 372 }
 373
 374 /**
 375  * Delete all entries in a hash table, but don't delete the table itself.
 376  * Invoke the given callback function for each table entry.
 377  *
 378  * \param table  the hash table to delete
 379  * \param callback  the callback function
 380  * \param userData  arbitrary pointer to pass along to the callback
 381  *                  (this is typically a struct gl_context pointer)
 382  */
 383 void
 384 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
 385                     void (*callback)(GLuint key, void *data, void *userData),
 386                     void *userData)
 387 {
 388    struct hash_entry *entry;
 389
 390    assert(table);
 391    assert(callback);
 392    mtx_lock(&table->Mutex);
 393    table->InDeleteAll = GL_TRUE;
 394    hash_table_foreach(table->ht, entry) {
 395       callback((uintptr_t)entry->key, entry->data, userData);
 396       _mesa_hash_table_remove(table->ht, entry);
 397    }
 398    if (table->deleted_key_data) {
 399       callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);
 400       table->deleted_key_data = NULL;
 401    }
 402    table->InDeleteAll = GL_FALSE;
 403    mtx_unlock(&table->Mutex);
 404 }
 405
 406
 407 /**
 408  * Walk over all entries in a hash table, calling callback function for each.
 409  * \param table  the hash table to walk
 410  * \param callback  the callback function
 411  * \param userData  arbitrary pointer to pass along to the callback
 412  *                  (this is typically a struct gl_context pointer)
 413  */
 414 void
 415 _mesa_HashWalk(const struct _mesa_HashTable *table,
 416                void (*callback)(GLuint key, void *data, void *userData),
 417                void *userData)
 418 {
 419    /* cast-away const */
 420    struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;
 421    struct hash_entry *entry;
 422
 423    assert(table);
 424    assert(callback);
 425    mtx_lock(&table2->Mutex);
 426    hash_table_foreach(table->ht, entry) {
 427       callback((uintptr_t)entry->key, entry->data, userData);
 428    }
 429    if (table->deleted_key_data)
 430       callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);
 431    mtx_unlock(&table2->Mutex);
 432 }
 433
 434 static void
 435 debug_print_entry(GLuint key, void *data, void *userData)
 436 {
 437    _mesa_debug(NULL, "%u %p\n", key, data);
 438 }
 439
 440 /**
 441  * Dump contents of hash table for debugging.
 442  *
 443  * \param table the hash table.
 444  */
 445 void
 446 _mesa_HashPrint(const struct _mesa_HashTable *table)
 447 {
 448    if (table->deleted_key_data)
 449       debug_print_entry(DELETED_KEY_VALUE, table->deleted_key_data, NULL);
 450    _mesa_HashWalk(table, debug_print_entry, NULL);
 451 }
 452
 453
 454 /**
 455  * Find a block of adjacent unused hash keys.
 456  *
 457  * \param table the hash table.
 458  * \param numKeys number of keys needed.
 459  *
 460  * \return Starting key of free block or 0 if failure.
 461  *
 462  * If there are enough free keys between the maximum key existing in the table
 463  * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
 464  * the adjacent key. Otherwise do a full search for a free key block in the
 465  * allowable key range.
 466  */
 467 GLuint
 468 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys)
 469 {
 470    const GLuint maxKey = ~((GLuint) 0) - 1;
 471    if (maxKey - numKeys > table->MaxKey) {
 472       /* the quick solution */
 473       return table->MaxKey + 1;
 474    }
 475    else {
 476       /* the slow solution */
 477       GLuint freeCount = 0;
 478       GLuint freeStart = 1;
 479       GLuint key;
 480       for (key = 1; key != maxKey; key++) {
 481          if (_mesa_HashLookup_unlocked(table, key)) {
 482             /* darn, this key is already in use */
 483             freeCount = 0;
 484             freeStart = key+1;
 485          }
 486          else {
 487             /* this key not in use, check if we've found enough */
 488             freeCount++;
 489             if (freeCount == numKeys) {
 490                return freeStart;
 491             }
 492          }
 493       }
 494       /* cannot allocate a block of numKeys consecutive keys */
 495       return 0;
 496    }
 497 }
 498
 499
 500 /**
 501  * Return the number of entries in the hash table.
 502  */
 503 GLuint
 504 _mesa_HashNumEntries(const struct _mesa_HashTable *table)
 505 {
 506    GLuint count = 0;
 507
 508    if (table->deleted_key_data)
 509       count++;
 510
 511    count += _mesa_hash_table_num_entries(table->ht);
 512
 513    return count;
 514 }