| /** |
| * \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 |
| * Version: 6.5.1 |
| * |
| * 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 |
| * BRIAN PAUL 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 "glapi/glthread.h" |
| #include "hash.h" |
| |
| |
| #define TABLE_SIZE 1023 /**< Size of lookup table/array */ |
| |
| #define HASH_FUNC(K) ((K) % TABLE_SIZE) |
| |
| |
| /** |
| * An entry in the hash table. |
| */ |
| struct HashEntry { |
| GLuint Key; /**< the entry's key */ |
| void *Data; /**< the entry's data */ |
| struct HashEntry *Next; /**< pointer to next entry */ |
| }; |
| |
| |
| /** |
| * The hash table data structure. |
| */ |
| struct _mesa_HashTable { |
| struct HashEntry *Table[TABLE_SIZE]; /**< the lookup table */ |
| GLuint MaxKey; /**< highest key inserted so far */ |
| _glthread_Mutex Mutex; /**< mutual exclusion lock */ |
| _glthread_Mutex WalkMutex; /**< for _mesa_HashWalk() */ |
| GLboolean InDeleteAll; /**< Debug check */ |
| }; |
| |
| |
| |
| /** |
| * 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) { |
| _glthread_INIT_MUTEX(table->Mutex); |
| _glthread_INIT_MUTEX(table->WalkMutex); |
| } |
| 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) |
| { |
| GLuint pos; |
| assert(table); |
| for (pos = 0; pos < TABLE_SIZE; pos++) { |
| struct HashEntry *entry = table->Table[pos]; |
| while (entry) { |
| struct HashEntry *next = entry->Next; |
| if (entry->Data) { |
| _mesa_problem(NULL, |
| "In _mesa_DeleteHashTable, found non-freed data"); |
| } |
| free(entry); |
| entry = next; |
| } |
| } |
| _glthread_DESTROY_MUTEX(table->Mutex); |
| _glthread_DESTROY_MUTEX(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) |
| { |
| GLuint pos; |
| const struct HashEntry *entry; |
| |
| assert(table); |
| assert(key); |
| |
| pos = HASH_FUNC(key); |
| entry = table->Table[pos]; |
| while (entry) { |
| if (entry->Key == key) { |
| return entry->Data; |
| } |
| entry = entry->Next; |
| } |
| return NULL; |
| } |
| |
| |
| /** |
| * 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); |
| _glthread_LOCK_MUTEX(table->Mutex); |
| res = _mesa_HashLookup_unlocked(table, key); |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return res; |
| } |
| |
| |
| /** |
| * 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) |
| { |
| /* search for existing entry with this key */ |
| GLuint pos; |
| struct HashEntry *entry; |
| |
| assert(table); |
| assert(key); |
| |
| _glthread_LOCK_MUTEX(table->Mutex); |
| |
| if (key > table->MaxKey) |
| table->MaxKey = key; |
| |
| pos = HASH_FUNC(key); |
| |
| /* check if replacing an existing entry with same key */ |
| for (entry = table->Table[pos]; entry; entry = entry->Next) { |
| if (entry->Key == key) { |
| /* replace entry's data */ |
| #if 0 /* not sure this check is always valid */ |
| if (entry->Data) { |
| _mesa_problem(NULL, "Memory leak detected in _mesa_HashInsert"); |
| } |
| #endif |
| entry->Data = data; |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return; |
| } |
| } |
| |
| /* alloc and insert new table entry */ |
| entry = MALLOC_STRUCT(HashEntry); |
| if (entry) { |
| entry->Key = key; |
| entry->Data = data; |
| entry->Next = table->Table[pos]; |
| table->Table[pos] = entry; |
| } |
| |
| _glthread_UNLOCK_MUTEX(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) |
| { |
| GLuint pos; |
| struct HashEntry *entry, *prev; |
| |
| 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; |
| } |
| |
| _glthread_LOCK_MUTEX(table->Mutex); |
| |
| pos = HASH_FUNC(key); |
| prev = NULL; |
| entry = table->Table[pos]; |
| while (entry) { |
| if (entry->Key == key) { |
| /* found it! */ |
| if (prev) { |
| prev->Next = entry->Next; |
| } |
| else { |
| table->Table[pos] = entry->Next; |
| } |
| free(entry); |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return; |
| } |
| prev = entry; |
| entry = entry->Next; |
| } |
| |
| _glthread_UNLOCK_MUTEX(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 GLcontext pointer) |
| */ |
| void |
| _mesa_HashDeleteAll(struct _mesa_HashTable *table, |
| void (*callback)(GLuint key, void *data, void *userData), |
| void *userData) |
| { |
| GLuint pos; |
| ASSERT(table); |
| ASSERT(callback); |
| _glthread_LOCK_MUTEX(table->Mutex); |
| table->InDeleteAll = GL_TRUE; |
| for (pos = 0; pos < TABLE_SIZE; pos++) { |
| struct HashEntry *entry, *next; |
| for (entry = table->Table[pos]; entry; entry = next) { |
| callback(entry->Key, entry->Data, userData); |
| next = entry->Next; |
| free(entry); |
| } |
| table->Table[pos] = NULL; |
| } |
| table->InDeleteAll = GL_FALSE; |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| } |
| |
| |
| /** |
| * 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 GLcontext 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; |
| GLuint pos; |
| ASSERT(table); |
| ASSERT(callback); |
| _glthread_LOCK_MUTEX(table2->WalkMutex); |
| for (pos = 0; pos < TABLE_SIZE; pos++) { |
| struct HashEntry *entry, *next; |
| for (entry = table->Table[pos]; entry; entry = next) { |
| /* save 'next' pointer now in case the callback deletes the entry */ |
| next = entry->Next; |
| callback(entry->Key, entry->Data, userData); |
| } |
| } |
| _glthread_UNLOCK_MUTEX(table2->WalkMutex); |
| } |
| |
| |
| /** |
| * Return the key of the "first" entry in the hash table. |
| * While holding the lock, walks through all table positions until finding |
| * the first entry of the first non-empty one. |
| * |
| * \param table the hash table |
| * \return key for the "first" entry in the hash table. |
| */ |
| GLuint |
| _mesa_HashFirstEntry(struct _mesa_HashTable *table) |
| { |
| GLuint pos; |
| assert(table); |
| _glthread_LOCK_MUTEX(table->Mutex); |
| for (pos = 0; pos < TABLE_SIZE; pos++) { |
| if (table->Table[pos]) { |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return table->Table[pos]->Key; |
| } |
| } |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return 0; |
| } |
| |
| |
| /** |
| * Given a hash table key, return the next key. This is used to walk |
| * over all entries in the table. Note that the keys returned during |
| * walking won't be in any particular order. |
| * \return next hash key or 0 if end of table. |
| */ |
| GLuint |
| _mesa_HashNextEntry(const struct _mesa_HashTable *table, GLuint key) |
| { |
| const struct HashEntry *entry; |
| GLuint pos; |
| |
| assert(table); |
| assert(key); |
| |
| /* Find the entry with given key */ |
| pos = HASH_FUNC(key); |
| for (entry = table->Table[pos]; entry ; entry = entry->Next) { |
| if (entry->Key == key) { |
| break; |
| } |
| } |
| |
| if (!entry) { |
| /* the given key was not found, so we can't find the next entry */ |
| return 0; |
| } |
| |
| if (entry->Next) { |
| /* return next in linked list */ |
| return entry->Next->Key; |
| } |
| else { |
| /* look for next non-empty table slot */ |
| pos++; |
| while (pos < TABLE_SIZE) { |
| if (table->Table[pos]) { |
| return table->Table[pos]->Key; |
| } |
| pos++; |
| } |
| return 0; |
| } |
| } |
| |
| |
| /** |
| * Dump contents of hash table for debugging. |
| * |
| * \param table the hash table. |
| */ |
| void |
| _mesa_HashPrint(const struct _mesa_HashTable *table) |
| { |
| GLuint pos; |
| assert(table); |
| for (pos = 0; pos < TABLE_SIZE; pos++) { |
| const struct HashEntry *entry = table->Table[pos]; |
| while (entry) { |
| _mesa_debug(NULL, "%u %p\n", entry->Key, entry->Data); |
| entry = entry->Next; |
| } |
| } |
| } |
| |
| |
| |
| /** |
| * 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); |
| _glthread_LOCK_MUTEX(table->Mutex); |
| if (maxKey - numKeys > table->MaxKey) { |
| /* the quick solution */ |
| _glthread_UNLOCK_MUTEX(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) { |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return freeStart; |
| } |
| } |
| } |
| /* cannot allocate a block of numKeys consecutive keys */ |
| _glthread_UNLOCK_MUTEX(table->Mutex); |
| return 0; |
| } |
| } |
| |
| |
| #if 0 /* debug only */ |
| |
| /** |
| * Test walking over all the entries in a hash table. |
| */ |
| static void |
| test_hash_walking(void) |
| { |
| struct _mesa_HashTable *t = _mesa_NewHashTable(); |
| const GLuint limit = 50000; |
| GLuint i; |
| |
| /* create some entries */ |
| for (i = 0; i < limit; i++) { |
| GLuint dummy; |
| GLuint k = (rand() % (limit * 10)) + 1; |
| while (_mesa_HashLookup(t, k)) { |
| /* id already in use, try another */ |
| k = (rand() % (limit * 10)) + 1; |
| } |
| _mesa_HashInsert(t, k, &dummy); |
| } |
| |
| /* walk over all entries */ |
| { |
| GLuint k = _mesa_HashFirstEntry(t); |
| GLuint count = 0; |
| while (k) { |
| GLuint knext = _mesa_HashNextEntry(t, k); |
| assert(knext != k); |
| _mesa_HashRemove(t, k); |
| count++; |
| k = knext; |
| } |
| assert(count == limit); |
| k = _mesa_HashFirstEntry(t); |
| assert(k==0); |
| } |
| |
| _mesa_DeleteHashTable(t); |
| } |
| |
| |
| void |
| _mesa_test_hash_functions(void) |
| { |
| int a, b, c; |
| struct _mesa_HashTable *t; |
| |
| t = _mesa_NewHashTable(); |
| _mesa_HashInsert(t, 501, &a); |
| _mesa_HashInsert(t, 10, &c); |
| _mesa_HashInsert(t, 0xfffffff8, &b); |
| /*_mesa_HashPrint(t);*/ |
| |
| assert(_mesa_HashLookup(t,501)); |
| assert(!_mesa_HashLookup(t,1313)); |
| assert(_mesa_HashFindFreeKeyBlock(t, 100)); |
| |
| _mesa_DeleteHashTable(t); |
| |
| test_hash_walking(); |
| } |
| |
| #endif |