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(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 }