/** * \file hash.c * Generic hash table. * * Used for display lists, texture objects, vertex/fragment programs, * buffer objects, etc. The hash functions are thread-safe. * * \note key=0 is illegal. * * \author Brian Paul */ /* * Mesa 3-D graphics library * * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ #include "glheader.h" #include "imports.h" #include "hash.h" #include "util/hash_table.h" /** * Magic GLuint object name that gets stored outside of the struct hash_table. * * The hash table needs a particular pointer to be the marker for a key that * was deleted from the table, along with NULL for the "never allocated in the * table" marker. Legacy GL allows any GLuint to be used as a GL object name, * and we use a 1:1 mapping from GLuints to key pointers, so we need to be * able to track a GLuint that happens to match the deleted key outside of * struct hash_table. We tell the hash table to use "1" as the deleted key * value, so that we test the deleted-key-in-the-table path as best we can. */ #define DELETED_KEY_VALUE 1 /** * The hash table data structure. */ struct _mesa_HashTable { struct hash_table *ht; GLuint MaxKey; /**< highest key inserted so far */ mtx_t Mutex; /**< mutual exclusion lock */ mtx_t WalkMutex; /**< for _mesa_HashWalk() */ GLboolean InDeleteAll; /**< Debug check */ /** Value that would be in the table for DELETED_KEY_VALUE. */ void *deleted_key_data; }; /** @{ * Mapping from our use of GLuint as both the key and the hash value to the * hash_table.h API * * There exist many integer hash functions, designed to avoid collisions when * the integers are spread across key space with some patterns. In GL, the * pattern (in the case of glGen*()ed object IDs) is that the keys are unique * contiguous integers starting from 1. Because of that, we just use the key * as the hash value, to minimize the cost of the hash function. If objects * are never deleted, we will never see a collision in the table, because the * table resizes itself when it approaches full, and thus key % table_size == * key. * * The case where we could have collisions for genned objects would be * something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50); * glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at * the end of that sequence, instead of 1-150. So far it doesn't appear to be * a problem. */ static bool uint_key_compare(const void *a, const void *b) { return a == b; } static uint32_t uint_hash(GLuint id) { return id; } static uint32_t uint_key_hash(const void *key) { return uint_hash((uintptr_t)key); } static void * uint_key(GLuint id) { return (void *)(uintptr_t) id; } /** @} */ /** * Create a new hash table. * * \return pointer to a new, empty hash table. */ struct _mesa_HashTable * _mesa_NewHashTable(void) { struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable); if (table) { table->ht = _mesa_hash_table_create(NULL, uint_key_hash, uint_key_compare); if (table->ht == NULL) { free(table); _mesa_error_no_memory(__func__); return NULL; } _mesa_hash_table_set_deleted_key(table->ht, uint_key(DELETED_KEY_VALUE)); mtx_init(&table->Mutex, mtx_plain); mtx_init(&table->WalkMutex, mtx_plain); } else { _mesa_error_no_memory(__func__); } return table; } /** * Delete a hash table. * Frees each entry on the hash table and then the hash table structure itself. * Note that the caller should have already traversed the table and deleted * the objects in the table (i.e. We don't free the entries' data pointer). * * \param table the hash table to delete. */ void _mesa_DeleteHashTable(struct _mesa_HashTable *table) { assert(table); if (_mesa_hash_table_next_entry(table->ht, NULL) != NULL) { _mesa_problem(NULL, "In _mesa_DeleteHashTable, found non-freed data"); } _mesa_hash_table_destroy(table->ht, NULL); mtx_destroy(&table->Mutex); mtx_destroy(&table->WalkMutex); free(table); } /** * Lookup an entry in the hash table, without locking. * \sa _mesa_HashLookup */ static inline void * _mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key) { const struct hash_entry *entry; assert(table); assert(key); if (key == DELETED_KEY_VALUE) return table->deleted_key_data; entry = _mesa_hash_table_search(table->ht, uint_key(key)); if (!entry) return NULL; return entry->data; } /** * Lookup an entry in the hash table. * * \param table the hash table. * \param key the key. * * \return pointer to user's data or NULL if key not in table */ void * _mesa_HashLookup(struct _mesa_HashTable *table, GLuint key) { void *res; assert(table); mtx_lock(&table->Mutex); res = _mesa_HashLookup_unlocked(table, key); mtx_unlock(&table->Mutex); return res; } /** * Lookup an entry in the hash table without locking the mutex. * * The hash table mutex must be locked manually by calling * _mesa_HashLockMutex() before calling this function. * * \param table the hash table. * \param key the key. * * \return pointer to user's data or NULL if key not in table */ void * _mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key) { return _mesa_HashLookup_unlocked(table, key); } /** * Lock the hash table mutex. * * This function should be used when multiple objects need * to be looked up in the hash table, to avoid having to lock * and unlock the mutex each time. * * \param table the hash table. */ void _mesa_HashLockMutex(struct _mesa_HashTable *table) { assert(table); mtx_lock(&table->Mutex); } /** * Unlock the hash table mutex. * * \param table the hash table. */ void _mesa_HashUnlockMutex(struct _mesa_HashTable *table) { assert(table); mtx_unlock(&table->Mutex); } static inline void _mesa_HashInsert_unlocked(struct _mesa_HashTable *table, GLuint key, void *data) { uint32_t hash = uint_hash(key); struct hash_entry *entry; assert(table); assert(key); if (key > table->MaxKey) table->MaxKey = key; if (key == DELETED_KEY_VALUE) { table->deleted_key_data = data; } else { entry = _mesa_hash_table_search_pre_hashed(table->ht, hash, uint_key(key)); if (entry) { entry->data = data; } else { _mesa_hash_table_insert_pre_hashed(table->ht, hash, uint_key(key), data); } } } /** * Insert a key/pointer pair into the hash table without locking the mutex. * If an entry with this key already exists we'll replace the existing entry. * * The hash table mutex must be locked manually by calling * _mesa_HashLockMutex() before calling this function. * * \param table the hash table. * \param key the key (not zero). * \param data pointer to user data. */ void _mesa_HashInsertLocked(struct _mesa_HashTable *table, GLuint key, void *data) { _mesa_HashInsert_unlocked(table, key, data); } /** * Insert a key/pointer pair into the hash table. * If an entry with this key already exists we'll replace the existing entry. * * \param table the hash table. * \param key the key (not zero). * \param data pointer to user data. */ void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data) { assert(table); mtx_lock(&table->Mutex); _mesa_HashInsert_unlocked(table, key, data); mtx_unlock(&table->Mutex); } /** * Remove an entry from the hash table. * * \param table the hash table. * \param key key of entry to remove. * * While holding the hash table's lock, searches the entry with the matching * key and unlinks it. */ void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key) { struct hash_entry *entry; assert(table); assert(key); /* have to check this outside of mutex lock */ if (table->InDeleteAll) { _mesa_problem(NULL, "_mesa_HashRemove illegally called from " "_mesa_HashDeleteAll callback function"); return; } mtx_lock(&table->Mutex); if (key == DELETED_KEY_VALUE) { table->deleted_key_data = NULL; } else { entry = _mesa_hash_table_search(table->ht, uint_key(key)); _mesa_hash_table_remove(table->ht, entry); } mtx_unlock(&table->Mutex); } /** * Delete all entries in a hash table, but don't delete the table itself. * Invoke the given callback function for each table entry. * * \param table the hash table to delete * \param callback the callback function * \param userData arbitrary pointer to pass along to the callback * (this is typically a struct gl_context pointer) */ void _mesa_HashDeleteAll(struct _mesa_HashTable *table, void (*callback)(GLuint key, void *data, void *userData), void *userData) { struct hash_entry *entry; ASSERT(table); ASSERT(callback); mtx_lock(&table->Mutex); table->InDeleteAll = GL_TRUE; hash_table_foreach(table->ht, entry) { callback((uintptr_t)entry->key, entry->data, userData); _mesa_hash_table_remove(table->ht, entry); } if (table->deleted_key_data) { callback(DELETED_KEY_VALUE, table->deleted_key_data, userData); table->deleted_key_data = NULL; } table->InDeleteAll = GL_FALSE; mtx_unlock(&table->Mutex); } /** * Clone all entries in a hash table, into a new table. * * \param table the hash table to clone */ struct _mesa_HashTable * _mesa_HashClone(const struct _mesa_HashTable *table) { /* cast-away const */ struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table; struct hash_entry *entry; struct _mesa_HashTable *clonetable; ASSERT(table); mtx_lock(&table2->Mutex); clonetable = _mesa_NewHashTable(); assert(clonetable); hash_table_foreach(table->ht, entry) { _mesa_HashInsert(clonetable, (GLint)(uintptr_t)entry->key, entry->data); } mtx_unlock(&table2->Mutex); return clonetable; } /** * Walk over all entries in a hash table, calling callback function for each. * Note: we use a separate mutex in this function to avoid a recursive * locking deadlock (in case the callback calls _mesa_HashRemove()) and to * prevent multiple threads/contexts from getting tangled up. * A lock-less version of this function could be used when the table will * not be modified. * \param table the hash table to walk * \param callback the callback function * \param userData arbitrary pointer to pass along to the callback * (this is typically a struct gl_context pointer) */ void _mesa_HashWalk(const struct _mesa_HashTable *table, void (*callback)(GLuint key, void *data, void *userData), void *userData) { /* cast-away const */ struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table; struct hash_entry *entry; ASSERT(table); ASSERT(callback); mtx_lock(&table2->WalkMutex); hash_table_foreach(table->ht, entry) { callback((uintptr_t)entry->key, entry->data, userData); } if (table->deleted_key_data) callback(DELETED_KEY_VALUE, table->deleted_key_data, userData); mtx_unlock(&table2->WalkMutex); } static void debug_print_entry(GLuint key, void *data, void *userData) { _mesa_debug(NULL, "%u %p\n", key, data); } /** * Dump contents of hash table for debugging. * * \param table the hash table. */ void _mesa_HashPrint(const struct _mesa_HashTable *table) { if (table->deleted_key_data) debug_print_entry(DELETED_KEY_VALUE, table->deleted_key_data, NULL); _mesa_HashWalk(table, debug_print_entry, NULL); } /** * Find a block of adjacent unused hash keys. * * \param table the hash table. * \param numKeys number of keys needed. * * \return Starting key of free block or 0 if failure. * * If there are enough free keys between the maximum key existing in the table * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return * the adjacent key. Otherwise do a full search for a free key block in the * allowable key range. */ GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys) { const GLuint maxKey = ~((GLuint) 0) - 1; mtx_lock(&table->Mutex); if (maxKey - numKeys > table->MaxKey) { /* the quick solution */ mtx_unlock(&table->Mutex); return table->MaxKey + 1; } else { /* the slow solution */ GLuint freeCount = 0; GLuint freeStart = 1; GLuint key; for (key = 1; key != maxKey; key++) { if (_mesa_HashLookup_unlocked(table, key)) { /* darn, this key is already in use */ freeCount = 0; freeStart = key+1; } else { /* this key not in use, check if we've found enough */ freeCount++; if (freeCount == numKeys) { mtx_unlock(&table->Mutex); return freeStart; } } } /* cannot allocate a block of numKeys consecutive keys */ mtx_unlock(&table->Mutex); return 0; } } /** * Return the number of entries in the hash table. */ GLuint _mesa_HashNumEntries(const struct _mesa_HashTable *table) { struct hash_entry *entry; GLuint count = 0; if (table->deleted_key_data) count++; hash_table_foreach(table->ht, entry) count++; return count; }