5 * Used for display lists, texture objects, vertex/fragment programs,
6 * buffer objects, etc. The hash functions are thread-safe.
8 * \note key=0 is illegal.
14 * Mesa 3-D graphics library
16 * Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
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:
25 * The above copyright notice and this permission notice shall be included
26 * in all copies or substantial portions of the Software.
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.
40 #include "util/hash_table.h"
43 * Magic GLuint object name that gets stored outside of the struct hash_table.
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.
53 #define DELETED_KEY_VALUE 1
56 * The hash table data structure.
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 mtx_t WalkMutex
; /**< for _mesa_HashWalk() */
63 GLboolean InDeleteAll
; /**< Debug check */
64 /** Value that would be in the table for DELETED_KEY_VALUE. */
65 void *deleted_key_data
;
69 * Mapping from our use of GLuint as both the key and the hash value to the
72 * There exist many integer hash functions, designed to avoid collisions when
73 * the integers are spread across key space with some patterns. In GL, the
74 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
75 * contiguous integers starting from 1. Because of that, we just use the key
76 * as the hash value, to minimize the cost of the hash function. If objects
77 * are never deleted, we will never see a collision in the table, because the
78 * table resizes itself when it approaches full, and thus key % table_size ==
81 * The case where we could have collisions for genned objects would be
82 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
83 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
84 * the end of that sequence, instead of 1-150. So far it doesn't appear to be
88 uint_key_compare(const void *a
, const void *b
)
100 uint_key_hash(const void *key
)
102 return uint_hash((uintptr_t)key
);
108 return (void *)(uintptr_t) id
;
113 * Create a new hash table.
115 * \return pointer to a new, empty hash table.
117 struct _mesa_HashTable
*
118 _mesa_NewHashTable(void)
120 struct _mesa_HashTable
*table
= CALLOC_STRUCT(_mesa_HashTable
);
123 table
->ht
= _mesa_hash_table_create(NULL
, uint_key_hash
,
125 if (table
->ht
== NULL
) {
127 _mesa_error_no_memory(__func__
);
131 _mesa_hash_table_set_deleted_key(table
->ht
, uint_key(DELETED_KEY_VALUE
));
132 mtx_init(&table
->Mutex
, mtx_plain
);
133 mtx_init(&table
->WalkMutex
, mtx_plain
);
136 _mesa_error_no_memory(__func__
);
145 * Delete a hash table.
146 * Frees each entry on the hash table and then the hash table structure itself.
147 * Note that the caller should have already traversed the table and deleted
148 * the objects in the table (i.e. We don't free the entries' data pointer).
150 * \param table the hash table to delete.
153 _mesa_DeleteHashTable(struct _mesa_HashTable
*table
)
157 if (_mesa_hash_table_next_entry(table
->ht
, NULL
) != NULL
) {
158 _mesa_problem(NULL
, "In _mesa_DeleteHashTable, found non-freed data");
161 _mesa_hash_table_destroy(table
->ht
, NULL
);
163 mtx_destroy(&table
->Mutex
);
164 mtx_destroy(&table
->WalkMutex
);
171 * Lookup an entry in the hash table, without locking.
172 * \sa _mesa_HashLookup
175 _mesa_HashLookup_unlocked(struct _mesa_HashTable
*table
, GLuint key
)
177 const struct hash_entry
*entry
;
182 if (key
== DELETED_KEY_VALUE
)
183 return table
->deleted_key_data
;
185 entry
= _mesa_hash_table_search(table
->ht
, uint_key(key
));
194 * Lookup an entry in the hash table.
196 * \param table the hash table.
197 * \param key the key.
199 * \return pointer to user's data or NULL if key not in table
202 _mesa_HashLookup(struct _mesa_HashTable
*table
, GLuint key
)
206 mtx_lock(&table
->Mutex
);
207 res
= _mesa_HashLookup_unlocked(table
, key
);
208 mtx_unlock(&table
->Mutex
);
214 * Lookup an entry in the hash table without locking the mutex.
216 * The hash table mutex must be locked manually by calling
217 * _mesa_HashLockMutex() before calling this function.
219 * \param table the hash table.
220 * \param key the key.
222 * \return pointer to user's data or NULL if key not in table
225 _mesa_HashLookupLocked(struct _mesa_HashTable
*table
, GLuint key
)
227 return _mesa_HashLookup_unlocked(table
, key
);
232 * Lock the hash table mutex.
234 * This function should be used when multiple objects need
235 * to be looked up in the hash table, to avoid having to lock
236 * and unlock the mutex each time.
238 * \param table the hash table.
241 _mesa_HashLockMutex(struct _mesa_HashTable
*table
)
244 mtx_lock(&table
->Mutex
);
249 * Unlock the hash table mutex.
251 * \param table the hash table.
254 _mesa_HashUnlockMutex(struct _mesa_HashTable
*table
)
257 mtx_unlock(&table
->Mutex
);
262 _mesa_HashInsert_unlocked(struct _mesa_HashTable
*table
, GLuint key
, void *data
)
264 uint32_t hash
= uint_hash(key
);
265 struct hash_entry
*entry
;
270 if (key
> table
->MaxKey
)
273 if (key
== DELETED_KEY_VALUE
) {
274 table
->deleted_key_data
= data
;
276 entry
= _mesa_hash_table_search_pre_hashed(table
->ht
, hash
, uint_key(key
));
280 _mesa_hash_table_insert_with_hash(table
->ht
, hash
, uint_key(key
), data
);
287 * Insert a key/pointer pair into the hash table without locking the mutex.
288 * If an entry with this key already exists we'll replace the existing entry.
290 * The hash table mutex must be locked manually by calling
291 * _mesa_HashLockMutex() before calling this function.
293 * \param table the hash table.
294 * \param key the key (not zero).
295 * \param data pointer to user data.
298 _mesa_HashInsertLocked(struct _mesa_HashTable
*table
, GLuint key
, void *data
)
300 _mesa_HashInsert_unlocked(table
, key
, data
);
305 * Insert a key/pointer pair into the hash table.
306 * If an entry with this key already exists we'll replace the existing entry.
308 * \param table the hash table.
309 * \param key the key (not zero).
310 * \param data pointer to user data.
313 _mesa_HashInsert(struct _mesa_HashTable
*table
, GLuint key
, void *data
)
316 mtx_lock(&table
->Mutex
);
317 _mesa_HashInsert_unlocked(table
, key
, data
);
318 mtx_unlock(&table
->Mutex
);
323 * Remove an entry from the hash table.
325 * \param table the hash table.
326 * \param key key of entry to remove.
328 * While holding the hash table's lock, searches the entry with the matching
329 * key and unlinks it.
332 _mesa_HashRemove(struct _mesa_HashTable
*table
, GLuint key
)
334 struct hash_entry
*entry
;
339 /* have to check this outside of mutex lock */
340 if (table
->InDeleteAll
) {
341 _mesa_problem(NULL
, "_mesa_HashRemove illegally called from "
342 "_mesa_HashDeleteAll callback function");
346 mtx_lock(&table
->Mutex
);
347 if (key
== DELETED_KEY_VALUE
) {
348 table
->deleted_key_data
= NULL
;
350 entry
= _mesa_hash_table_search(table
->ht
, uint_key(key
));
351 _mesa_hash_table_remove(table
->ht
, entry
);
353 mtx_unlock(&table
->Mutex
);
359 * Delete all entries in a hash table, but don't delete the table itself.
360 * Invoke the given callback function for each table entry.
362 * \param table the hash table to delete
363 * \param callback the callback function
364 * \param userData arbitrary pointer to pass along to the callback
365 * (this is typically a struct gl_context pointer)
368 _mesa_HashDeleteAll(struct _mesa_HashTable
*table
,
369 void (*callback
)(GLuint key
, void *data
, void *userData
),
372 struct hash_entry
*entry
;
376 mtx_lock(&table
->Mutex
);
377 table
->InDeleteAll
= GL_TRUE
;
378 hash_table_foreach(table
->ht
, entry
) {
379 callback((uintptr_t)entry
->key
, entry
->data
, userData
);
380 _mesa_hash_table_remove(table
->ht
, entry
);
382 if (table
->deleted_key_data
) {
383 callback(DELETED_KEY_VALUE
, table
->deleted_key_data
, userData
);
384 table
->deleted_key_data
= NULL
;
386 table
->InDeleteAll
= GL_FALSE
;
387 mtx_unlock(&table
->Mutex
);
392 * Clone all entries in a hash table, into a new table.
394 * \param table the hash table to clone
396 struct _mesa_HashTable
*
397 _mesa_HashClone(const struct _mesa_HashTable
*table
)
399 /* cast-away const */
400 struct _mesa_HashTable
*table2
= (struct _mesa_HashTable
*) table
;
401 struct hash_entry
*entry
;
402 struct _mesa_HashTable
*clonetable
;
405 mtx_lock(&table2
->Mutex
);
407 clonetable
= _mesa_NewHashTable();
409 hash_table_foreach(table
->ht
, entry
) {
410 _mesa_HashInsert(clonetable
, (GLint
)(uintptr_t)entry
->key
, entry
->data
);
413 mtx_unlock(&table2
->Mutex
);
420 * Walk over all entries in a hash table, calling callback function for each.
421 * Note: we use a separate mutex in this function to avoid a recursive
422 * locking deadlock (in case the callback calls _mesa_HashRemove()) and to
423 * prevent multiple threads/contexts from getting tangled up.
424 * A lock-less version of this function could be used when the table will
426 * \param table the hash table to walk
427 * \param callback the callback function
428 * \param userData arbitrary pointer to pass along to the callback
429 * (this is typically a struct gl_context pointer)
432 _mesa_HashWalk(const struct _mesa_HashTable
*table
,
433 void (*callback
)(GLuint key
, void *data
, void *userData
),
436 /* cast-away const */
437 struct _mesa_HashTable
*table2
= (struct _mesa_HashTable
*) table
;
438 struct hash_entry
*entry
;
442 mtx_lock(&table2
->WalkMutex
);
443 hash_table_foreach(table
->ht
, entry
) {
444 callback((uintptr_t)entry
->key
, entry
->data
, userData
);
446 if (table
->deleted_key_data
)
447 callback(DELETED_KEY_VALUE
, table
->deleted_key_data
, userData
);
448 mtx_unlock(&table2
->WalkMutex
);
452 debug_print_entry(GLuint key
, void *data
, void *userData
)
454 _mesa_debug(NULL
, "%u %p\n", key
, data
);
458 * Dump contents of hash table for debugging.
460 * \param table the hash table.
463 _mesa_HashPrint(const struct _mesa_HashTable
*table
)
465 if (table
->deleted_key_data
)
466 debug_print_entry(DELETED_KEY_VALUE
, table
->deleted_key_data
, NULL
);
467 _mesa_HashWalk(table
, debug_print_entry
, NULL
);
472 * Find a block of adjacent unused hash keys.
474 * \param table the hash table.
475 * \param numKeys number of keys needed.
477 * \return Starting key of free block or 0 if failure.
479 * If there are enough free keys between the maximum key existing in the table
480 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
481 * the adjacent key. Otherwise do a full search for a free key block in the
482 * allowable key range.
485 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable
*table
, GLuint numKeys
)
487 const GLuint maxKey
= ~((GLuint
) 0) - 1;
488 mtx_lock(&table
->Mutex
);
489 if (maxKey
- numKeys
> table
->MaxKey
) {
490 /* the quick solution */
491 mtx_unlock(&table
->Mutex
);
492 return table
->MaxKey
+ 1;
495 /* the slow solution */
496 GLuint freeCount
= 0;
497 GLuint freeStart
= 1;
499 for (key
= 1; key
!= maxKey
; key
++) {
500 if (_mesa_HashLookup_unlocked(table
, key
)) {
501 /* darn, this key is already in use */
506 /* this key not in use, check if we've found enough */
508 if (freeCount
== numKeys
) {
509 mtx_unlock(&table
->Mutex
);
514 /* cannot allocate a block of numKeys consecutive keys */
515 mtx_unlock(&table
->Mutex
);
522 * Return the number of entries in the hash table.
525 _mesa_HashNumEntries(const struct _mesa_HashTable
*table
)
527 struct hash_entry
*entry
;
530 if (table
->deleted_key_data
)
533 hash_table_foreach(table
->ht
, entry
)