/* 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)

 * 

 *           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

 * 

 * @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

 * 

 *           APR_FLOCK_SHARED

 *           APR_FLOCK_EXCLUSIVE

 * 

 * @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

 * 

 *           APR_SDBM_INSERT     return an error if the record exists

 *           APR_SDBM_REPLACE    overwrite any existing record for key

 * 

 */

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 */