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.
39 #include "glapi/glthread.h"
41 #include "hash_table.h"
44 * Magic GLuint object name that gets stored outside of the struct hash_table.
46 * The hash table needs a particular pointer to be the marker for a key that
47 * was deleted from the table, along with NULL for the "never allocated in the
48 * table" marker. Legacy GL allows any GLuint to be used as a GL object name,
49 * and we use a 1:1 mapping from GLuints to key pointers, so we need to be
50 * able to track a GLuint that happens to match the deleted key outside of
51 * struct hash_table. We tell the hash table to use "1" as the deleted key
52 * value, so that we test the deleted-key-in-the-table path as best we can.
54 #define DELETED_KEY_VALUE 1
57 * The hash table data structure.
59 struct _mesa_HashTable {
60 struct hash_table *ht;
61 GLuint MaxKey; /**< highest key inserted so far */
62 _glthread_Mutex Mutex; /**< mutual exclusion lock */
63 _glthread_Mutex WalkMutex; /**< for _mesa_HashWalk() */
64 GLboolean InDeleteAll; /**< Debug check */
65 /** Value that would be in the table for DELETED_KEY_VALUE. */
66 void *deleted_key_data;
70 * Mapping from our use of GLuint as both the key and the hash value to the
73 * There exist many integer hash functions, designed to avoid collisions when
74 * the integers are spread across key space with some patterns. In GL, the
75 * pattern (in the case of glGen*()ed object IDs) is that the keys are unique
76 * contiguous integers starting from 1. Because of that, we just use the key
77 * as the hash value, to minimize the cost of the hash function. If objects
78 * are never deleted, we will never see a collision in the table, because the
79 * table resizes itself when it approaches full, and thus key % table_size ==
82 * The case where we could have collisions for genned objects would be
83 * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
84 * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
85 * the end of that sequence, instead of 1-150. So far it doesn't appear to be
89 uint_key_compare(const void *a, const void *b)
103 return (void *)(uintptr_t) id;
108 * Create a new hash table.
110 * \return pointer to a new, empty hash table.
112 struct _mesa_HashTable *
113 _mesa_NewHashTable(void)
115 struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable);
118 table->ht = _mesa_hash_table_create(NULL, uint_key_compare);
119 _mesa_hash_table_set_deleted_key(table->ht, uint_key(DELETED_KEY_VALUE));
120 _glthread_INIT_MUTEX(table->Mutex);
121 _glthread_INIT_MUTEX(table->WalkMutex);
129 * Delete a hash table.
130 * Frees each entry on the hash table and then the hash table structure itself.
131 * Note that the caller should have already traversed the table and deleted
132 * the objects in the table (i.e. We don't free the entries' data pointer).
134 * \param table the hash table to delete.
137 _mesa_DeleteHashTable(struct _mesa_HashTable *table)
141 if (_mesa_hash_table_next_entry(table->ht, NULL) != NULL) {
142 _mesa_problem(NULL, "In _mesa_DeleteHashTable, found non-freed data");
145 _mesa_hash_table_destroy(table->ht, NULL);
147 _glthread_DESTROY_MUTEX(table->Mutex);
148 _glthread_DESTROY_MUTEX(table->WalkMutex);
155 * Lookup an entry in the hash table, without locking.
156 * \sa _mesa_HashLookup
159 _mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key)
161 const struct hash_entry *entry;
166 if (key == DELETED_KEY_VALUE)
167 return table->deleted_key_data;
169 entry = _mesa_hash_table_search(table->ht, uint_hash(key), uint_key(key));
178 * Lookup an entry in the hash table.
180 * \param table the hash table.
181 * \param key the key.
183 * \return pointer to user's data or NULL if key not in table
186 _mesa_HashLookup(struct _mesa_HashTable *table, GLuint key)
190 _glthread_LOCK_MUTEX(table->Mutex);
191 res = _mesa_HashLookup_unlocked(table, key);
192 _glthread_UNLOCK_MUTEX(table->Mutex);
198 * Insert a key/pointer pair into the hash table.
199 * If an entry with this key already exists we'll replace the existing entry.
201 * \param table the hash table.
202 * \param key the key (not zero).
203 * \param data pointer to user data.
206 _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data)
208 uint32_t hash = uint_hash(key);
209 struct hash_entry *entry;
214 _glthread_LOCK_MUTEX(table->Mutex);
216 if (key > table->MaxKey)
219 if (key == DELETED_KEY_VALUE) {
220 table->deleted_key_data = data;
222 entry = _mesa_hash_table_search(table->ht, hash, uint_key(key));
226 _mesa_hash_table_insert(table->ht, hash, uint_key(key), data);
230 _glthread_UNLOCK_MUTEX(table->Mutex);
236 * Remove an entry from the hash table.
238 * \param table the hash table.
239 * \param key key of entry to remove.
241 * While holding the hash table's lock, searches the entry with the matching
242 * key and unlinks it.
245 _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)
247 struct hash_entry *entry;
252 /* have to check this outside of mutex lock */
253 if (table->InDeleteAll) {
254 _mesa_problem(NULL, "_mesa_HashRemove illegally called from "
255 "_mesa_HashDeleteAll callback function");
259 _glthread_LOCK_MUTEX(table->Mutex);
260 if (key == DELETED_KEY_VALUE) {
261 table->deleted_key_data = NULL;
263 entry = _mesa_hash_table_search(table->ht, uint_hash(key), uint_key(key));
264 _mesa_hash_table_remove(table->ht, entry);
266 _glthread_UNLOCK_MUTEX(table->Mutex);
272 * Delete all entries in a hash table, but don't delete the table itself.
273 * Invoke the given callback function for each table entry.
275 * \param table the hash table to delete
276 * \param callback the callback function
277 * \param userData arbitrary pointer to pass along to the callback
278 * (this is typically a struct gl_context pointer)
281 _mesa_HashDeleteAll(struct _mesa_HashTable *table,
282 void (*callback)(GLuint key, void *data, void *userData),
285 struct hash_entry *entry;
289 _glthread_LOCK_MUTEX(table->Mutex);
290 table->InDeleteAll = GL_TRUE;
291 hash_table_foreach(table->ht, entry) {
292 callback((uintptr_t)entry->key, entry->data, userData);
293 _mesa_hash_table_remove(table->ht, entry);
295 if (table->deleted_key_data) {
296 callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);
297 table->deleted_key_data = NULL;
299 table->InDeleteAll = GL_FALSE;
300 _glthread_UNLOCK_MUTEX(table->Mutex);
305 * Walk over all entries in a hash table, calling callback function for each.
306 * Note: we use a separate mutex in this function to avoid a recursive
307 * locking deadlock (in case the callback calls _mesa_HashRemove()) and to
308 * prevent multiple threads/contexts from getting tangled up.
309 * A lock-less version of this function could be used when the table will
311 * \param table the hash table to walk
312 * \param callback the callback function
313 * \param userData arbitrary pointer to pass along to the callback
314 * (this is typically a struct gl_context pointer)
317 _mesa_HashWalk(const struct _mesa_HashTable *table,
318 void (*callback)(GLuint key, void *data, void *userData),
321 /* cast-away const */
322 struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;
323 struct hash_entry *entry;
327 _glthread_LOCK_MUTEX(table2->WalkMutex);
328 hash_table_foreach(table->ht, entry) {
329 callback((uintptr_t)entry->key, entry->data, userData);
331 if (table->deleted_key_data)
332 callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);
333 _glthread_UNLOCK_MUTEX(table2->WalkMutex);
337 debug_print_entry(GLuint key, void *data, void *userData)
339 _mesa_debug(NULL, "%u %p\n", key, data);
343 * Dump contents of hash table for debugging.
345 * \param table the hash table.
348 _mesa_HashPrint(const struct _mesa_HashTable *table)
350 if (table->deleted_key_data)
351 debug_print_entry(DELETED_KEY_VALUE, table->deleted_key_data, NULL);
352 _mesa_HashWalk(table, debug_print_entry, NULL);
357 * Find a block of adjacent unused hash keys.
359 * \param table the hash table.
360 * \param numKeys number of keys needed.
362 * \return Starting key of free block or 0 if failure.
364 * If there are enough free keys between the maximum key existing in the table
365 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return
366 * the adjacent key. Otherwise do a full search for a free key block in the
367 * allowable key range.
370 _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys)
372 const GLuint maxKey = ~((GLuint) 0) - 1;
373 _glthread_LOCK_MUTEX(table->Mutex);
374 if (maxKey - numKeys > table->MaxKey) {
375 /* the quick solution */
376 _glthread_UNLOCK_MUTEX(table->Mutex);
377 return table->MaxKey + 1;
380 /* the slow solution */
381 GLuint freeCount = 0;
382 GLuint freeStart = 1;
384 for (key = 1; key != maxKey; key++) {
385 if (_mesa_HashLookup_unlocked(table, key)) {
386 /* darn, this key is already in use */
391 /* this key not in use, check if we've found enough */
393 if (freeCount == numKeys) {
394 _glthread_UNLOCK_MUTEX(table->Mutex);
399 /* cannot allocate a block of numKeys consecutive keys */
400 _glthread_UNLOCK_MUTEX(table->Mutex);
407 * Return the number of entries in the hash table.
410 _mesa_HashNumEntries(const struct _mesa_HashTable *table)
412 struct hash_entry *entry;
415 if (table->deleted_key_data)
418 hash_table_foreach(table->ht, entry)