diff options
Diffstat (limited to 'src/common/db.c')
| -rw-r--r-- | src/common/db.c | 164 |
1 files changed, 85 insertions, 79 deletions
diff --git a/src/common/db.c b/src/common/db.c index 306d713dd..87b6e7c4f 100644 --- a/src/common/db.c +++ b/src/common/db.c @@ -1,68 +1,68 @@ /*****************************************************************************\ - * Copyright (c) Athena Dev Teams - Licensed under GNU GPL * - * For more information, see LICENCE in the main folder * - * * - * This file is separated in five sections: * - * (1) Private typedefs, enums, structures, defines and gblobal variables * - * (2) Private functions * - * (3) Protected functions used internally * - * (4) Protected functions used in the interface of the database * - * (5) Public functions * - * * - * The databases are structured as a hashtable of RED-BLACK trees. * - * * - * <B>Properties of the RED-BLACK trees being used:</B> * - * 1. The value of any node is greater than the value of its left child and * - * less than the value of its right child. * - * 2. Every node is colored either RED or BLACK. * - * 3. Every red node that is not a leaf has only black children. * - * 4. Every path from the root to a leaf contains the same number of black * - * nodes. * - * 5. The root node is black. * - * An <code>n</code> node in a RED-BLACK tree has the property that its * - * height is <code>O(lg(n))</code>. * - * Another important property is that after adding a node to a RED-BLACK * - * tree, the tree can be readjusted in <code>O(lg(n))</code> time. * - * Similarly, after deleting a node from a RED-BLACK tree, the tree can be * - * readjusted in <code>O(lg(n))</code> time. * - * {@link http://www.cs.mcgill.ca/~cs251/OldCourses/1997/topic18/} * - * * - * <B>How to add new database types:</B> * - * 1. Add the identifier of the new database type to the enum DBType * - * 2. If not already there, add the data type of the key to the union DBKey * - * 3. If the key can be considered NULL, update the function db_is_key_null * - * 4. If the key can be duplicated, update the functions db_dup_key and * - * db_dup_key_free * - * 5. Create a comparator and update the function db_default_cmp * - * 6. Create a hasher and update the function db_default_hash * - * 7. If the new database type requires or does not support some options, * - * update the function db_fix_options * - * * - * TODO: * - * - create test cases to test the database system thoroughly * - * - make data an enumeration * - * - finish this header describing the database system * - * - create custom database allocator * - * - make the system thread friendly * - * - change the structure of the database to T-Trees * - * - create a db that organizes itself by splaying * - * * - * HISTORY: * - * 2.1 (Athena build #???#) - Portability fix * - * - Fixed the portability of casting to union and added the functions * - * {@link DB#ensure(DB,DBKey,DBCreateData,...)} and * - * {@link DB#clear(DB,DBApply,...)}. * - * 2.0 (Athena build 4859) - Transition version * - * - Almost everything recoded with a strategy similar to objects, * - * database structure is maintained. * - * 1.0 (up to Athena build 4706) * - * - Previous database system. * - * * - * @version 2.1 (Athena build #???#) - Portability fix * - * @author (Athena build 4859) Flavio @ Amazon Project * - * @author (up to Athena build 4706) Athena Dev Teams * - * @encoding US-ASCII * - * @see common#db.h * + * Copyright (c) Athena Dev Teams - Licensed under GNU GPL + * For more information, see LICENCE in the main folder + * + * This file is separated in five sections: + * (1) Private typedefs, enums, structures, defines and gblobal variables + * (2) Private functions + * (3) Protected functions used internally + * (4) Protected functions used in the interface of the database + * (5) Public functions + * + * The databases are structured as a hashtable of RED-BLACK trees. + * + * <B>Properties of the RED-BLACK trees being used:</B> + * 1. The value of any node is greater than the value of its left child and + * less than the value of its right child. + * 2. Every node is colored either RED or BLACK. + * 3. Every red node that is not a leaf has only black children. + * 4. Every path from the root to a leaf contains the same number of black + * nodes. + * 5. The root node is black. + * An <code>n</code> node in a RED-BLACK tree has the property that its + * height is <code>O(lg(n))</code>. + * Another important property is that after adding a node to a RED-BLACK + * tree, the tree can be readjusted in <code>O(lg(n))</code> time. + * Similarly, after deleting a node from a RED-BLACK tree, the tree can be + * readjusted in <code>O(lg(n))</code> time. + * {@link http://www.cs.mcgill.ca/~cs251/OldCourses/1997/topic18/} + * + * <B>How to add new database types:</B> + * 1. Add the identifier of the new database type to the enum DBType + * 2. If not already there, add the data type of the key to the union DBKey + * 3. If the key can be considered NULL, update the function db_is_key_null + * 4. If the key can be duplicated, update the functions db_dup_key and + * db_dup_key_free + * 5. Create a comparator and update the function db_default_cmp + * 6. Create a hasher and update the function db_default_hash + * 7. If the new database type requires or does not support some options, + * update the function db_fix_options + * + * TODO: + * - create test cases to test the database system thoroughly + * - make data an enumeration + * - finish this header describing the database system + * - create custom database allocator + * - make the system thread friendly + * - change the structure of the database to T-Trees + * - create a db that organizes itself by splaying + * + * HISTORY: + * 2006/12/21 - Added 1-node cache to the database. + * 2.1 (Athena build #???#) - Portability fix + * - Fixed the portability of casting to union and added the functions + * {@link DB#ensure(DB,DBKey,DBCreateData,...)} and + * {@link DB#clear(DB,DBApply,...)}. + * 2.0 (Athena build 4859) - Transition version + * - Almost everything recoded with a strategy similar to objects, + * database structure is maintained. + * 1.0 (up to Athena build 4706) + * - Previous database system. + * + * @version 2006/12/21 + * @author Athena Dev team + * @encoding US-ASCII + * @see #db.h \*****************************************************************************/ #include <stdio.h> #include <stdlib.h> @@ -182,9 +182,10 @@ typedef struct db { DBHasher hash; DBReleaser release; DBNode ht[HASH_SIZE]; + DBNode cache; DBType type; DBOptions options; - unsigned int item_count; + uint32 item_count; unsigned short maxlen; unsigned global_lock : 1; } *DB_impl; @@ -1129,6 +1130,9 @@ static void *db_obj_get(DB self, DBKey key) return NULL; // nullpo candidate } + if (db->cache && db->cmp(key, db->cache->key, db->maxlen) == 0) + return db->cache->data; // cache hit + db_free_lock(db); node = db->ht[db->hash(key, db->maxlen)%HASH_SIZE]; while (node) { @@ -1142,6 +1146,7 @@ static void *db_obj_get(DB self, DBKey key) else node = node->right; } + db->cache = node; db_free_unlock(db); return data; } @@ -1277,6 +1282,9 @@ static void *db_obj_vensure(DB self, DBKey key, DBCreateData create, va_list arg return NULL; // nullpo candidate } + if (db->cache && db->cmp(key, db->cache->key, db->maxlen) == 0) + return db->cache->data; // cache hit + db_free_lock(db); hash = db->hash(key, db->maxlen)%HASH_SIZE; node = db->ht[hash]; @@ -1293,7 +1301,7 @@ static void *db_obj_vensure(DB self, DBKey key, DBCreateData create, va_list arg } // Create node if necessary if (node == NULL) { - if (db->item_count == (unsigned int)~0) { + if (db->item_count == UINT32_MAX) { ShowError("db_vensure: item_count overflow, aborting item insertion.\n" "Database allocated at %s:%d", db->alloc_file, db->alloc_line); @@ -1334,6 +1342,7 @@ static void *db_obj_vensure(DB self, DBKey key, DBCreateData create, va_list arg node->data = create(key, args); } data = node->data; + db->cache = node; db_free_unlock(db); return data; } @@ -1408,7 +1417,7 @@ static void *db_obj_put(DB self, DBKey key, void *data) return NULL; // nullpo candidate } - if (db->item_count == (unsigned int)~0) { + if (db->item_count == UINT32_MAX) { ShowError("db_put: item_count overflow, aborting item insertion.\n" "Database allocated at %s:%d", db->alloc_file, db->alloc_line); @@ -1471,6 +1480,7 @@ static void *db_obj_put(DB self, DBKey key, void *data) node->key = key; } node->data = data; + db->cache = node; db_free_unlock(db); return old_data; } @@ -1515,6 +1525,8 @@ static void *db_obj_remove(DB self, DBKey key) c = db->cmp(key, node->key, db->maxlen); if (c == 0) { if (!(node->deleted)) { + if (db->cache == node) + db->cache = NULL; data = node->data; db->release(node->key, node->data, DB_RELEASE_DATA); db_free_add(db, node, &db->ht[hash]); @@ -1641,6 +1653,7 @@ static int db_obj_vclear(DB self, DBApply func, va_list args) if (db == NULL) return 0; // nullpo candidate db_free_lock(db); + db->cache = NULL; for (i = 0; i < HASH_SIZE; i++) { // Apply the func and delete in the order: left tree, right tree, current node node = db->ht[i]; @@ -1750,18 +1763,10 @@ static int db_obj_vdestroy(DB self, DBApply func, va_list args) #ifdef DB_ENABLE_STATS switch (db->type) { - case DB_INT: - COUNT(db_int_destroy); - break; - case DB_UINT: - COUNT(db_uint_destroy); - break; - case DB_STRING: - COUNT(db_string_destroy); - break; - case DB_ISTRING: - COUNT(db_istring_destroy); - break; + case DB_INT: COUNT(db_int_destroy); break; + case DB_UINT: COUNT(db_uint_destroy); break; + case DB_STRING: COUNT(db_string_destroy); break; + case DB_ISTRING: COUNT(db_istring_destroy); break; } #endif /* DB_ENABLE_STATS */ db_free_lock(db); @@ -2110,6 +2115,7 @@ DB db_alloc(const char *file, int line, DBType type, DBOptions options, unsigned db->release = db_default_release(type, options); for (i = 0; i < HASH_SIZE; i++) db->ht[i] = NULL; + db->cache = NULL; db->type = type; db->options = options; db->item_count = 0; |