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
17 * Copyright (C) 1999-2005 Brian Paul All Rights Reserved.
19 * Permission is hereby granted, free of charge, to any person obtaining a
20 * copy of this software and associated documentation files (the "Software"),
21 * to deal in the Software without restriction, including without limitation
22 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
23 * and/or sell copies of the Software, and to permit persons to whom the
24 * Software is furnished to do so, subject to the following conditions:
26 * The above copyright notice and this permission notice shall be included
27 * in all copies or substantial portions of the Software.
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
30 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
32 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
33 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
34 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
44 #define TABLE_SIZE 1023 /**< Size of lookup table/array */
46 #define HASH_FUNC(K) ((K) % TABLE_SIZE)
50 * An entry in the hash table.
52 * This struct is private to this file.
55 GLuint Key
; /**< the entry's key */
56 void *Data
; /**< the entry's data */
57 struct HashEntry
*Next
; /**< pointer to next entry */
61 * The hash table data structure.
63 * This is an opaque types (it's not defined in hash.h file).
65 struct _mesa_HashTable
{
66 struct HashEntry
*Table
[TABLE_SIZE
]; /**< the lookup table */
67 GLuint MaxKey
; /**< highest key inserted so far */
68 _glthread_Mutex Mutex
; /**< mutual exclusion lock */
73 * Create a new hash table.
75 * \return pointer to a new, empty hash table.
77 struct _mesa_HashTable
*
78 _mesa_NewHashTable(void)
80 struct _mesa_HashTable
*table
= CALLOC_STRUCT(_mesa_HashTable
);
82 _glthread_INIT_MUTEX(table
->Mutex
);
90 * Delete a hash table.
91 * Frees each entry on the hash table and then the hash table structure itself.
92 * Note that the caller should have already traversed the table and deleted
93 * the objects in the table (i.e. We don't free the entries' data pointer).
95 * \param table the hash table to delete.
98 _mesa_DeleteHashTable(struct _mesa_HashTable
*table
)
102 for (i
= 0; i
< TABLE_SIZE
; i
++) {
103 struct HashEntry
*entry
= table
->Table
[i
];
105 struct HashEntry
*next
= entry
->Next
;
110 _glthread_DESTROY_MUTEX(table
->Mutex
);
117 * Lookup an entry in the hash table.
119 * \param table the hash table.
120 * \param key the key.
122 * \return pointer to user's data or NULL if key not in table
125 _mesa_HashLookup(const struct _mesa_HashTable
*table
, GLuint key
)
128 const struct HashEntry
*entry
;
133 pos
= HASH_FUNC(key
);
134 entry
= table
->Table
[pos
];
136 if (entry
->Key
== key
) {
147 * Insert a key/pointer pair into the hash table.
148 * If an entry with this key already exists we'll replace the existing entry.
150 * \param table the hash table.
151 * \param key the key (not zero).
152 * \param data pointer to user data.
155 _mesa_HashInsert(struct _mesa_HashTable
*table
, GLuint key
, void *data
)
157 /* search for existing entry with this key */
159 struct HashEntry
*entry
;
164 _glthread_LOCK_MUTEX(table
->Mutex
);
166 if (key
> table
->MaxKey
)
169 pos
= HASH_FUNC(key
);
170 entry
= table
->Table
[pos
];
172 if (entry
->Key
== key
) {
173 /* replace entry's data */
175 _glthread_UNLOCK_MUTEX(table
->Mutex
);
181 /* alloc and insert new table entry */
182 entry
= MALLOC_STRUCT(HashEntry
);
185 entry
->Next
= table
->Table
[pos
];
186 table
->Table
[pos
] = entry
;
188 _glthread_UNLOCK_MUTEX(table
->Mutex
);
194 * Remove an entry from the hash table.
196 * \param table the hash table.
197 * \param key key of entry to remove.
199 * While holding the hash table's lock, searches the entry with the matching
200 * key and unlinks it.
203 _mesa_HashRemove(struct _mesa_HashTable
*table
, GLuint key
)
206 struct HashEntry
*entry
, *prev
;
211 _glthread_LOCK_MUTEX(table
->Mutex
);
213 pos
= HASH_FUNC(key
);
215 entry
= table
->Table
[pos
];
217 if (entry
->Key
== key
) {
220 prev
->Next
= entry
->Next
;
223 table
->Table
[pos
] = entry
->Next
;
226 _glthread_UNLOCK_MUTEX(table
->Mutex
);
233 _glthread_UNLOCK_MUTEX(table
->Mutex
);
239 * Get the key of the "first" entry in the hash table.
241 * This is used in the course of deleting all display lists when
242 * a context is destroyed.
244 * \param table the hash table
246 * \return key for the "first" entry in the hash table.
248 * While holding the lock, walks through all table positions until finding
249 * the first entry of the first non-empty one.
252 _mesa_HashFirstEntry(struct _mesa_HashTable
*table
)
256 _glthread_LOCK_MUTEX(table
->Mutex
);
257 for (pos
=0; pos
< TABLE_SIZE
; pos
++) {
258 if (table
->Table
[pos
]) {
259 _glthread_UNLOCK_MUTEX(table
->Mutex
);
260 return table
->Table
[pos
]->Key
;
263 _glthread_UNLOCK_MUTEX(table
->Mutex
);
269 * Given a hash table key, return the next key. This is used to walk
270 * over all entries in the table. Note that the keys returned during
271 * walking won't be in any particular order.
272 * \return next hash key or 0 if end of table.
275 _mesa_HashNextEntry(const struct _mesa_HashTable
*table
, GLuint key
)
277 const struct HashEntry
*entry
;
283 /* Find the entry with given key */
284 pos
= HASH_FUNC(key
);
285 entry
= table
->Table
[pos
];
287 if (entry
->Key
== key
) {
294 /* the key was not found, we can't find next entry */
299 /* return next in linked list */
300 return entry
->Next
->Key
;
303 /* look for next non-empty table slot */
305 while (pos
< TABLE_SIZE
) {
306 if (table
->Table
[pos
]) {
307 return table
->Table
[pos
]->Key
;
317 * Dump contents of hash table for debugging.
319 * \param table the hash table.
322 _mesa_HashPrint(const struct _mesa_HashTable
*table
)
326 for (i
=0;i
<TABLE_SIZE
;i
++) {
327 const struct HashEntry
*entry
= table
->Table
[i
];
329 _mesa_debug(NULL
, "%u %p\n", entry
->Key
, entry
->Data
);
338 * Find a block of adjacent unused hash keys.
340 * \param table the hash table.
341 * \param numKeys number of keys needed.
343 * \return Starting key of free block or 0 if failure.
345 * If there are enough free keys between the maximum key existing in the table
346 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
347 * the adjacent key. Otherwise do a full search for a free key block in the
348 * allowable key range.
351 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable
*table
, GLuint numKeys
)
353 GLuint maxKey
= ~((GLuint
) 0);
354 _glthread_LOCK_MUTEX(table
->Mutex
);
355 if (maxKey
- numKeys
> table
->MaxKey
) {
356 /* the quick solution */
357 _glthread_UNLOCK_MUTEX(table
->Mutex
);
358 return table
->MaxKey
+ 1;
361 /* the slow solution */
362 GLuint freeCount
= 0;
363 GLuint freeStart
= 1;
365 for (key
=1; key
!=maxKey
; key
++) {
366 if (_mesa_HashLookup(table
, key
)) {
367 /* darn, this key is already in use */
372 /* this key not in use, check if we've found enough */
374 if (freeCount
== numKeys
) {
375 _glthread_UNLOCK_MUTEX(table
->Mutex
);
380 /* cannot allocate a block of numKeys consecutive keys */
381 _glthread_UNLOCK_MUTEX(table
->Mutex
);
388 * Test walking over all the entries in a hash table.
391 test_hash_walking(void)
393 struct _mesa_HashTable
*t
= _mesa_NewHashTable();
394 const GLuint limit
= 50000;
397 /* create some entries */
398 for (i
= 0; i
< limit
; i
++) {
400 GLuint k
= (rand() % (limit
* 10)) + 1;
401 while (_mesa_HashLookup(t
, k
)) {
402 /* id already in use, try another */
403 k
= (rand() % (limit
* 10)) + 1;
405 _mesa_HashInsert(t
, k
, &dummy
);
408 /* walk over all entries */
410 GLuint k
= _mesa_HashFirstEntry(t
);
413 GLuint knext
= _mesa_HashNextEntry(t
, k
);
415 _mesa_HashRemove(t
, k
);
419 assert(count
== limit
);
420 k
= _mesa_HashFirstEntry(t
);
424 _mesa_DeleteHashTable(t
);
429 _mesa_test_hash_functions(void)
432 struct _mesa_HashTable
*t
;
434 t
= _mesa_NewHashTable();
435 _mesa_HashInsert(t
, 501, &a
);
436 _mesa_HashInsert(t
, 10, &c
);
437 _mesa_HashInsert(t
, 0xfffffff8, &b
);
438 /*_mesa_HashPrint(t);*/
440 assert(_mesa_HashLookup(t
,501));
441 assert(!_mesa_HashLookup(t
,1313));
442 assert(_mesa_HashFindFreeKeyBlock(t
, 100));
444 _mesa_DeleteHashTable(t
);