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) 1999-2006 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.
40 #include "glapi/glthread.h"
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.
53 GLuint Key
; /**< the entry's key */
54 void *Data
; /**< the entry's data */
55 struct HashEntry
*Next
; /**< pointer to next entry */
60 * The hash table data structure.
62 struct _mesa_HashTable
{
63 struct HashEntry
*Table
[TABLE_SIZE
]; /**< the lookup table */
64 GLuint MaxKey
; /**< highest key inserted so far */
65 _glthread_Mutex Mutex
; /**< mutual exclusion lock */
66 _glthread_Mutex WalkMutex
; /**< for _mesa_HashWalk() */
67 GLboolean InDeleteAll
; /**< Debug check */
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
);
83 _glthread_INIT_MUTEX(table
->WalkMutex
);
91 * Delete a hash table.
92 * Frees each entry on the hash table and then the hash table structure itself.
93 * Note that the caller should have already traversed the table and deleted
94 * the objects in the table (i.e. We don't free the entries' data pointer).
96 * \param table the hash table to delete.
99 _mesa_DeleteHashTable(struct _mesa_HashTable
*table
)
103 for (pos
= 0; pos
< TABLE_SIZE
; pos
++) {
104 struct HashEntry
*entry
= table
->Table
[pos
];
106 struct HashEntry
*next
= entry
->Next
;
109 "In _mesa_DeleteHashTable, found non-freed data");
115 _glthread_DESTROY_MUTEX(table
->Mutex
);
116 _glthread_DESTROY_MUTEX(table
->WalkMutex
);
123 * Lookup an entry in the hash table.
125 * \param table the hash table.
126 * \param key the key.
128 * \return pointer to user's data or NULL if key not in table
131 _mesa_HashLookup(const struct _mesa_HashTable
*table
, GLuint key
)
134 const struct HashEntry
*entry
;
139 pos
= HASH_FUNC(key
);
140 entry
= table
->Table
[pos
];
142 if (entry
->Key
== key
) {
153 * Insert a key/pointer pair into the hash table.
154 * If an entry with this key already exists we'll replace the existing entry.
156 * \param table the hash table.
157 * \param key the key (not zero).
158 * \param data pointer to user data.
161 _mesa_HashInsert(struct _mesa_HashTable
*table
, GLuint key
, void *data
)
163 /* search for existing entry with this key */
165 struct HashEntry
*entry
;
170 _glthread_LOCK_MUTEX(table
->Mutex
);
172 if (key
> table
->MaxKey
)
175 pos
= HASH_FUNC(key
);
177 /* check if replacing an existing entry with same key */
178 for (entry
= table
->Table
[pos
]; entry
; entry
= entry
->Next
) {
179 if (entry
->Key
== key
) {
180 /* replace entry's data */
181 #if 0 /* not sure this check is always valid */
183 _mesa_problem(NULL
, "Memory leak detected in _mesa_HashInsert");
187 _glthread_UNLOCK_MUTEX(table
->Mutex
);
192 /* alloc and insert new table entry */
193 entry
= MALLOC_STRUCT(HashEntry
);
196 entry
->Next
= table
->Table
[pos
];
197 table
->Table
[pos
] = entry
;
199 _glthread_UNLOCK_MUTEX(table
->Mutex
);
205 * Remove an entry from the hash table.
207 * \param table the hash table.
208 * \param key key of entry to remove.
210 * While holding the hash table's lock, searches the entry with the matching
211 * key and unlinks it.
214 _mesa_HashRemove(struct _mesa_HashTable
*table
, GLuint key
)
217 struct HashEntry
*entry
, *prev
;
222 /* have to check this outside of mutex lock */
223 if (table
->InDeleteAll
) {
224 _mesa_problem(NULL
, "_mesa_HashRemove illegally called from "
225 "_mesa_HashDeleteAll callback function");
229 _glthread_LOCK_MUTEX(table
->Mutex
);
231 pos
= HASH_FUNC(key
);
233 entry
= table
->Table
[pos
];
235 if (entry
->Key
== key
) {
238 prev
->Next
= entry
->Next
;
241 table
->Table
[pos
] = entry
->Next
;
244 _glthread_UNLOCK_MUTEX(table
->Mutex
);
251 _glthread_UNLOCK_MUTEX(table
->Mutex
);
257 * Delete all entries in a hash table, but don't delete the table itself.
258 * Invoke the given callback function for each table entry.
260 * \param table the hash table to delete
261 * \param callback the callback function
262 * \param userData arbitrary pointer to pass along to the callback
263 * (this is typically a GLcontext pointer)
266 _mesa_HashDeleteAll(struct _mesa_HashTable
*table
,
267 void (*callback
)(GLuint key
, void *data
, void *userData
),
273 _glthread_LOCK_MUTEX(table
->Mutex
);
274 table
->InDeleteAll
= GL_TRUE
;
275 for (pos
= 0; pos
< TABLE_SIZE
; pos
++) {
276 struct HashEntry
*entry
, *next
;
277 for (entry
= table
->Table
[pos
]; entry
; entry
= next
) {
278 callback(entry
->Key
, entry
->Data
, userData
);
282 table
->Table
[pos
] = NULL
;
284 table
->InDeleteAll
= GL_FALSE
;
285 _glthread_UNLOCK_MUTEX(table
->Mutex
);
290 * Walk over all entries in a hash table, calling callback function for each.
291 * Note: we use a separate mutex in this function to avoid a recursive
292 * locking deadlock (in case the callback calls _mesa_HashRemove()) and to
293 * prevent multiple threads/contexts from getting tangled up.
294 * A lock-less version of this function could be used when the table will
296 * \param table the hash table to walk
297 * \param callback the callback function
298 * \param userData arbitrary pointer to pass along to the callback
299 * (this is typically a GLcontext pointer)
302 _mesa_HashWalk(const struct _mesa_HashTable
*table
,
303 void (*callback
)(GLuint key
, void *data
, void *userData
),
306 /* cast-away const */
307 struct _mesa_HashTable
*table2
= (struct _mesa_HashTable
*) table
;
311 _glthread_LOCK_MUTEX(table2
->WalkMutex
);
312 for (pos
= 0; pos
< TABLE_SIZE
; pos
++) {
313 struct HashEntry
*entry
, *next
;
314 for (entry
= table
->Table
[pos
]; entry
; entry
= next
) {
315 /* save 'next' pointer now in case the callback deletes the entry */
317 callback(entry
->Key
, entry
->Data
, userData
);
320 _glthread_UNLOCK_MUTEX(table2
->WalkMutex
);
325 * Return the key of the "first" entry in the hash table.
326 * While holding the lock, walks through all table positions until finding
327 * the first entry of the first non-empty one.
329 * \param table the hash table
330 * \return key for the "first" entry in the hash table.
333 _mesa_HashFirstEntry(struct _mesa_HashTable
*table
)
337 _glthread_LOCK_MUTEX(table
->Mutex
);
338 for (pos
= 0; pos
< TABLE_SIZE
; pos
++) {
339 if (table
->Table
[pos
]) {
340 _glthread_UNLOCK_MUTEX(table
->Mutex
);
341 return table
->Table
[pos
]->Key
;
344 _glthread_UNLOCK_MUTEX(table
->Mutex
);
350 * Given a hash table key, return the next key. This is used to walk
351 * over all entries in the table. Note that the keys returned during
352 * walking won't be in any particular order.
353 * \return next hash key or 0 if end of table.
356 _mesa_HashNextEntry(const struct _mesa_HashTable
*table
, GLuint key
)
358 const struct HashEntry
*entry
;
364 /* Find the entry with given key */
365 pos
= HASH_FUNC(key
);
366 for (entry
= table
->Table
[pos
]; entry
; entry
= entry
->Next
) {
367 if (entry
->Key
== key
) {
373 /* the given key was not found, so we can't find the next entry */
378 /* return next in linked list */
379 return entry
->Next
->Key
;
382 /* look for next non-empty table slot */
384 while (pos
< TABLE_SIZE
) {
385 if (table
->Table
[pos
]) {
386 return table
->Table
[pos
]->Key
;
396 * Dump contents of hash table for debugging.
398 * \param table the hash table.
401 _mesa_HashPrint(const struct _mesa_HashTable
*table
)
405 for (pos
= 0; pos
< TABLE_SIZE
; pos
++) {
406 const struct HashEntry
*entry
= table
->Table
[pos
];
408 _mesa_debug(NULL
, "%u %p\n", entry
->Key
, entry
->Data
);
417 * Find a block of adjacent unused hash keys.
419 * \param table the hash table.
420 * \param numKeys number of keys needed.
422 * \return Starting key of free block or 0 if failure.
424 * If there are enough free keys between the maximum key existing in the table
425 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
426 * the adjacent key. Otherwise do a full search for a free key block in the
427 * allowable key range.
430 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable
*table
, GLuint numKeys
)
432 const GLuint maxKey
= ~((GLuint
) 0);
433 _glthread_LOCK_MUTEX(table
->Mutex
);
434 if (maxKey
- numKeys
> table
->MaxKey
) {
435 /* the quick solution */
436 _glthread_UNLOCK_MUTEX(table
->Mutex
);
437 return table
->MaxKey
+ 1;
440 /* the slow solution */
441 GLuint freeCount
= 0;
442 GLuint freeStart
= 1;
444 for (key
= 1; key
!= maxKey
; key
++) {
445 if (_mesa_HashLookup(table
, key
)) {
446 /* darn, this key is already in use */
451 /* this key not in use, check if we've found enough */
453 if (freeCount
== numKeys
) {
454 _glthread_UNLOCK_MUTEX(table
->Mutex
);
459 /* cannot allocate a block of numKeys consecutive keys */
460 _glthread_UNLOCK_MUTEX(table
->Mutex
);
466 #if 0 /* debug only */
469 * Test walking over all the entries in a hash table.
472 test_hash_walking(void)
474 struct _mesa_HashTable
*t
= _mesa_NewHashTable();
475 const GLuint limit
= 50000;
478 /* create some entries */
479 for (i
= 0; i
< limit
; i
++) {
481 GLuint k
= (rand() % (limit
* 10)) + 1;
482 while (_mesa_HashLookup(t
, k
)) {
483 /* id already in use, try another */
484 k
= (rand() % (limit
* 10)) + 1;
486 _mesa_HashInsert(t
, k
, &dummy
);
489 /* walk over all entries */
491 GLuint k
= _mesa_HashFirstEntry(t
);
494 GLuint knext
= _mesa_HashNextEntry(t
, k
);
496 _mesa_HashRemove(t
, k
);
500 assert(count
== limit
);
501 k
= _mesa_HashFirstEntry(t
);
505 _mesa_DeleteHashTable(t
);
510 _mesa_test_hash_functions(void)
513 struct _mesa_HashTable
*t
;
515 t
= _mesa_NewHashTable();
516 _mesa_HashInsert(t
, 501, &a
);
517 _mesa_HashInsert(t
, 10, &c
);
518 _mesa_HashInsert(t
, 0xfffffff8, &b
);
519 /*_mesa_HashPrint(t);*/
521 assert(_mesa_HashLookup(t
,501));
522 assert(!_mesa_HashLookup(t
,1313));
523 assert(_mesa_HashFindFreeKeyBlock(t
, 100));
525 _mesa_DeleteHashTable(t
);