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Filename :
apr_sdbm.h
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/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * sdbm - ndbm work-alike hashed database library * based on Per-Ake Larson's Dynamic Hashing algorithms. BIT 18 (1978). * author: oz@nexus.yorku.ca * status: ex-public domain */ #ifndef APR_SDBM_H #define APR_SDBM_H #include "apu.h" #include "apr_errno.h" #include "apr_file_io.h" /* for apr_fileperms_t */ /** * @file apr_sdbm.h * @brief apr-util SDBM library */ /** * @defgroup APR_Util_DBM_SDBM SDBM library * @ingroup APR_Util_DBM * @{ */ /** * Structure for referencing an sdbm */ typedef struct apr_sdbm_t apr_sdbm_t; /** * Structure for referencing the datum record within an sdbm */ typedef struct { /** pointer to the data stored/retrieved */ char *dptr; /** size of data */ /* apr_ssize_t for release 2.0??? */ int dsize; } apr_sdbm_datum_t; /* The extensions used for the database files */ /** SDBM Directory file extension */ #define APR_SDBM_DIRFEXT ".dir" /** SDBM page file extension */ #define APR_SDBM_PAGFEXT ".pag" /* flags to sdbm_store */ #define APR_SDBM_INSERT 0 /**< Insert */ #define APR_SDBM_REPLACE 1 /**< Replace */ #define APR_SDBM_INSERTDUP 2 /**< Insert with duplicates */ /** * Open an sdbm database by file name * @param db The newly opened database * @param name The sdbm file to open * @param mode The flag values (APR_READ and APR_BINARY flags are implicit) * <PRE> * APR_WRITE open for read-write access * APR_CREATE create the sdbm if it does not exist * APR_TRUNCATE empty the contents of the sdbm * APR_EXCL fail for APR_CREATE if the file exists * APR_DELONCLOSE delete the sdbm when closed * APR_SHARELOCK support locking across process/machines * </PRE> * @param perms Permissions to apply to if created * @param p The pool to use when creating the sdbm * @remark The sdbm name is not a true file name, as sdbm appends suffixes * for seperate data and index files. */ APU_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *name, apr_int32_t mode, apr_fileperms_t perms, apr_pool_t *p); /** * Close an sdbm file previously opened by apr_sdbm_open * @param db The database to close */ APU_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db); /** * Lock an sdbm database for concurency of multiple operations * @param db The database to lock * @param type The lock type * <PRE> * APR_FLOCK_SHARED * APR_FLOCK_EXCLUSIVE * </PRE> * @remark Calls to apr_sdbm_lock may be nested. All apr_sdbm functions * perform implicit locking. Since an APR_FLOCK_SHARED lock cannot be * portably promoted to an APR_FLOCK_EXCLUSIVE lock, apr_sdbm_store and * apr_sdbm_delete calls will fail if an APR_FLOCK_SHARED lock is held. * The apr_sdbm_lock call requires the database to be opened with the * APR_SHARELOCK mode value. */ APU_DECLARE(apr_status_t) apr_sdbm_lock(apr_sdbm_t *db, int type); /** * Release an sdbm lock previously aquired by apr_sdbm_lock * @param db The database to unlock */ APU_DECLARE(apr_status_t) apr_sdbm_unlock(apr_sdbm_t *db); /** * Fetch an sdbm record value by key * @param db The database * @param value The value datum retrieved for this record * @param key The key datum to find this record */ APU_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db, apr_sdbm_datum_t *value, apr_sdbm_datum_t key); /** * Store an sdbm record value by key * @param db The database * @param key The key datum to store this record by * @param value The value datum to store in this record * @param opt The method used to store the record * <PRE> * APR_SDBM_INSERT return an error if the record exists * APR_SDBM_REPLACE overwrite any existing record for key * </PRE> */ APU_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key, apr_sdbm_datum_t value, int opt); /** * Delete an sdbm record value by key * @param db The database * @param key The key datum of the record to delete * @remark It is not an error to delete a non-existent record. */ APU_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db, const apr_sdbm_datum_t key); /** * Retrieve the first record key from a dbm * @param db The database * @param key The key datum of the first record * @remark The keys returned are not ordered. To traverse the list of keys * for an sdbm opened with APR_SHARELOCK, the caller must use apr_sdbm_lock * prior to retrieving the first record, and hold the lock until after the * last call to apr_sdbm_nextkey. */ APU_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db, apr_sdbm_datum_t *key); /** * Retrieve the next record key from an sdbm * @param db The database * @param key The key datum of the next record */ APU_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db, apr_sdbm_datum_t *key); /** * Returns true if the sdbm database opened for read-only access * @param db The database to test */ APU_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db); /** @} */ #endif /* APR_SDBM_H */