Apache Portable Runtime
apr_sdbm.h
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00001 /* Licensed to the Apache Software Foundation (ASF) under one or more
00002  * contributor license agreements.  See the NOTICE file distributed with
00003  * this work for additional information regarding copyright ownership.
00004  * The ASF licenses this file to You under the Apache License, Version 2.0
00005  * (the "License"); you may not use this file except in compliance with
00006  * the License.  You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 /*
00018  * sdbm - ndbm work-alike hashed database library
00019  * based on Per-Ake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
00020  * author: oz@nexus.yorku.ca
00021  * status: ex-public domain
00022  */
00023 
00024 #ifndef APR_SDBM_H
00025 #define APR_SDBM_H
00026 
00027 #include "apu.h"
00028 #include "apr_errno.h"
00029 #include "apr_file_io.h"   /* for apr_fileperms_t */
00030 
00031 /** 
00032  * @file apr_sdbm.h
00033  * @brief apr-util SDBM library
00034  */
00035 /**
00036  * @defgroup APR_Util_DBM_SDBM SDBM library
00037  * @ingroup APR_Util_DBM
00038  * @{
00039  */
00040 
00041 /**
00042  * Structure for referencing an sdbm
00043  */
00044 typedef struct apr_sdbm_t apr_sdbm_t;
00045 
00046 /**
00047  * Structure for referencing the datum record within an sdbm
00048  */
00049 typedef struct {
00050     /** pointer to the data stored/retrieved */
00051     char *dptr;
00052     /** size of data */
00053     /* apr_ssize_t for release 2.0??? */
00054     int dsize;
00055 } apr_sdbm_datum_t;
00056 
00057 /* The extensions used for the database files */
00058 /** SDBM Directory file extension */
00059 #define APR_SDBM_DIRFEXT        ".dir"
00060 /** SDBM page file extension */
00061 #define APR_SDBM_PAGFEXT        ".pag"
00062 
00063 /* flags to sdbm_store */
00064 #define APR_SDBM_INSERT     0   /**< Insert */
00065 #define APR_SDBM_REPLACE    1   /**< Replace */
00066 #define APR_SDBM_INSERTDUP  2   /**< Insert with duplicates */
00067 
00068 /**
00069  * Open an sdbm database by file name
00070  * @param db The newly opened database
00071  * @param name The sdbm file to open
00072  * @param mode The flag values (APR_READ and APR_BINARY flags are implicit)
00073  * <PRE>
00074  *           APR_WRITE          open for read-write access
00075  *           APR_CREATE         create the sdbm if it does not exist
00076  *           APR_TRUNCATE       empty the contents of the sdbm
00077  *           APR_EXCL           fail for APR_CREATE if the file exists
00078  *           APR_DELONCLOSE     delete the sdbm when closed
00079  *           APR_SHARELOCK      support locking across process/machines
00080  * </PRE>
00081  * @param perms Permissions to apply to if created
00082  * @param p The pool to use when creating the sdbm
00083  * @remark The sdbm name is not a true file name, as sdbm appends suffixes 
00084  * for seperate data and index files.
00085  */
00086 APR_DECLARE(apr_status_t) apr_sdbm_open(apr_sdbm_t **db, const char *name, 
00087                                         apr_int32_t mode, 
00088                                         apr_fileperms_t perms, apr_pool_t *p);
00089 
00090 /**
00091  * Close an sdbm file previously opened by apr_sdbm_open
00092  * @param db The database to close
00093  */
00094 APR_DECLARE(apr_status_t) apr_sdbm_close(apr_sdbm_t *db);
00095 
00096 /**
00097  * Lock an sdbm database for concurency of multiple operations
00098  * @param db The database to lock
00099  * @param type The lock type
00100  * <PRE>
00101  *           APR_FLOCK_SHARED
00102  *           APR_FLOCK_EXCLUSIVE
00103  * </PRE>
00104  * @remark Calls to apr_sdbm_lock may be nested.  All apr_sdbm functions
00105  * perform implicit locking.  Since an APR_FLOCK_SHARED lock cannot be 
00106  * portably promoted to an APR_FLOCK_EXCLUSIVE lock, apr_sdbm_store and 
00107  * apr_sdbm_delete calls will fail if an APR_FLOCK_SHARED lock is held.
00108  * The apr_sdbm_lock call requires the database to be opened with the
00109  * APR_SHARELOCK mode value.
00110  */
00111 APR_DECLARE(apr_status_t) apr_sdbm_lock(apr_sdbm_t *db, int type);
00112 
00113 /**
00114  * Release an sdbm lock previously aquired by apr_sdbm_lock
00115  * @param db The database to unlock
00116  */
00117 APR_DECLARE(apr_status_t) apr_sdbm_unlock(apr_sdbm_t *db);
00118 
00119 /**
00120  * Fetch an sdbm record value by key
00121  * @param db The database 
00122  * @param value The value datum retrieved for this record
00123  * @param key The key datum to find this record
00124  */
00125 APR_DECLARE(apr_status_t) apr_sdbm_fetch(apr_sdbm_t *db, 
00126                                          apr_sdbm_datum_t *value, 
00127                                          apr_sdbm_datum_t key);
00128 
00129 /**
00130  * Store an sdbm record value by key
00131  * @param db The database 
00132  * @param key The key datum to store this record by
00133  * @param value The value datum to store in this record
00134  * @param opt The method used to store the record
00135  * <PRE>
00136  *           APR_SDBM_INSERT     return an error if the record exists
00137  *           APR_SDBM_REPLACE    overwrite any existing record for key
00138  * </PRE>
00139  */
00140 APR_DECLARE(apr_status_t) apr_sdbm_store(apr_sdbm_t *db, apr_sdbm_datum_t key,
00141                                          apr_sdbm_datum_t value, int opt);
00142 
00143 /**
00144  * Delete an sdbm record value by key
00145  * @param db The database 
00146  * @param key The key datum of the record to delete
00147  * @remark It is not an error to delete a non-existent record.
00148  */
00149 APR_DECLARE(apr_status_t) apr_sdbm_delete(apr_sdbm_t *db, 
00150                                           const apr_sdbm_datum_t key);
00151 
00152 /**
00153  * Retrieve the first record key from a dbm
00154  * @param db The database 
00155  * @param key The key datum of the first record
00156  * @remark The keys returned are not ordered.  To traverse the list of keys
00157  * for an sdbm opened with APR_SHARELOCK, the caller must use apr_sdbm_lock
00158  * prior to retrieving the first record, and hold the lock until after the
00159  * last call to apr_sdbm_nextkey.
00160  */
00161 APR_DECLARE(apr_status_t) apr_sdbm_firstkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
00162 
00163 /**
00164  * Retrieve the next record key from an sdbm
00165  * @param db The database 
00166  * @param key The key datum of the next record
00167  */
00168 APR_DECLARE(apr_status_t) apr_sdbm_nextkey(apr_sdbm_t *db, apr_sdbm_datum_t *key);
00169 
00170 /**
00171  * Returns true if the sdbm database opened for read-only access
00172  * @param db The database to test
00173  */
00174 APR_DECLARE(int) apr_sdbm_rdonly(apr_sdbm_t *db);
00175 /** @} */
00176 #endif /* APR_SDBM_H */
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