CURIA(3)                    Quick Database Manager                    CURIA(3)



NAME
       Curia - the extended API of QDBM


SYNOPSIS
       #include <depot.h>
       #include <curia.h>
       #include <stdlib.h>

       CURIA *cropen(const char *name, int omode, int bnum, int dnum);

       int crclose(CURIA *curia);

       int crput(CURIA *curia, const char *kbuf, int ksiz, const char *vbuf,
       int vsiz, int dmode);

       int crout(CURIA *curia, const char *kbuf, int ksiz);

       char *crget(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, int *sp);

       int crgetwb(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, char *vbuf);

       int crvsiz(CURIA *curia, const char *kbuf, int ksiz);

       int criterinit(CURIA *curia);

       char *criternext(CURIA *curia, int *sp);

       int crsetalign(CURIA *curia, int align);

       int crsetfbpsiz(CURIA *curia, int size);

       int crsync(CURIA *curia);

       int croptimize(CURIA *curia, int bnum);

       char *crname(CURIA *curia);

       int crfsiz(CURIA *curia);

       double crfsizd(CURIA *curia);

       int crbnum(CURIA *curia);

       int crbusenum(CURIA *curia);

       int crrnum(CURIA *curia);

       int crwritable(CURIA *curia);

       int crfatalerror(CURIA *curia);

       int crinode(CURIA *curia);

       time_t crmtime(CURIA *curia);

       int crremove(const char *name);

       int crrepair(const char *name);

       int crexportdb(CURIA *curia, const char *name);

       int crimportdb(CURIA *curia, const char *name);

       char *crsnaffle(const char *name, const char *kbuf, int ksiz, int *sp);

       int crputlob(CURIA *curia, const char *kbuf, int ksiz, const char
       *vbuf, int vsiz, int dmode);

       int croutlob(CURIA *curia, const char *kbuf, int ksiz);

       char *crgetlob(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, int *sp);

       int crgetlobfd(CURIA *curia, const char *kbuf, int ksiz);

       int crvsizlob(CURIA *curia, const char *kbuf, int ksiz);

       int crrnumlob(CURIA *curia);


DESCRIPTION
       Curia is the extended API of QDBM.  It provides routines for managing
       multiple database files in a directory.  Restrictions of some file
       systems that the size of each file is limited are escaped by dividing a
       database file into two or more.  If the database files deploy on
       multiple devices, the scalability is improved.

       Although Depot creates a database with a file name, Curia creates a
       database with a directory name.  A database file named as `depot' is
       placed in the specified directory.  Although it keeps the attribute of
       the database, it does not keep the entities of the records.  Besides,
       sub directories are created by the number of division of the database,
       named with 4 digits.  The database files are placed in the
       subdirectories.  The entities of the records are stored in the database
       file.  For example, in the case that a database directory named as
       `casket' and the number of division is 3, `casket/depot',
       `casket/0001/depot', `casket/0002/depot' and `casket/0003/depot' are
       created.  No error occurs even if the namesake directory exists when
       creating a database.  So, if sub directories exists and some devices
       are mounted on the sub directories, the database files deploy on the
       multiple devices.  It is possible for the database files to deploy on
       multiple file servers using NFS and so on.

       Curia features managing large objects.  Although usual records are
       stored in some database files, records of large objects are stored in
       individual files.  Because the files of large objects are deployed in
       different directories named with the hash values, the access speed is
       part-way robust although it is slower than the speed of usual records.
       Large and not often accessed data should be secluded as large objects.
       By doing this, the access speed of usual records is improved.  The
       directory hierarchies of large objects are placed in the directory
       named as `lob' in the sub directories of the database.  Because the key
       spaces of the usual records and the large objects are different, the
       operations keep out of each other.

       In order to use Curia, you should include `depot.h', `curia.h' and
       `stdlib.h' in the source files.  Usually, the following description
       will be near the beginning of a source file.

              #include <depot.h>
              #include <curia.h>
              #include <stdlib.h>

       A pointer to `CURIA' is used as a database handle.  It is like that
       some file I/O routines of `stdio.h' use a pointer to `FILE'.  A
       database handle is opened with the function `cropen' and closed with
       `crclose'.  You should not refer directly to any member of the handle.
       If a fatal error occurs in a database, any access method via the handle
       except `crclose' will not work and return error status.  Although a
       process is allowed to use multiple database handles at the same time,
       handles of the same database directory should not be used.

       Curia also assign the external variable `dpecode' with the error code.
       The function `dperrmsg' is used in order to get the message of the
       error code.

       The function `cropen' is used in order to get a database handle.

       CURIA *cropen(const char *name, int omode, int bnum, int dnum);
              `name' specifies the name of a database directory.  `omode'
              specifies the connection mode: `CR_OWRITER' as a writer,
              `CR_OREADER' as a reader.  If the mode is `CR_OWRITER', the
              following may be added by bitwise or: `CR_OCREAT', which means
              it creates a new database if not exist, `CR_OTRUNC', which means
              it creates a new database regardless if one exists.  Both of
              `CR_OREADER' and `CR_OWRITER' can be added to by bitwise or:
              `CR_ONOLCK', which means it opens a database directory without
              file locking, or `CR_OLCKNB', which means locking is performed
              without blocking.  `CR_OCREAT' can be added to by bitwise or:
              `CR_OSPARSE', which means it creates database files as sparse
              files.  `bnum' specifies the number of elements of each bucket
              array.  If it is not more than 0, the default value is
              specified.  The size of each bucket array is determined on
              creating, and can not be changed except for by optimization of
              the database.  Suggested size of each bucket array is about from
              0.5 to 4 times of the number of all records to store.  `dnum'
              specifies the number of division of the database.  If it is not
              more than 0, the default value is specified.  The number of
              division can not be changed from the initial value.  The max
              number of division is 512.  The return value is the database
              handle or `NULL' if it is not successful.  While connecting as a
              writer, an exclusive lock is invoked to the database directory.
              While connecting as a reader, a shared lock is invoked to the
              database directory.  The thread blocks until the lock is
              achieved.  If `CR_ONOLCK' is used, the application is
              responsible for exclusion control.

       The function `crclose' is used in order to close a database handle.

       int crclose(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is true, else, it is false.  Because the region of a
              closed handle is released, it becomes impossible to use the
              handle.  Updating a database is assured to be written when the
              handle is closed.  If a writer opens a database but does not
              close it appropriately, the database will be broken.

       The function `crput' is used in order to store a record.

       int crput(CURIA *curia, const char *kbuf, int ksiz, const char *vbuf,
       int vsiz, int dmode);
              `curia' specifies a database handle connected as a writer.
              `kbuf' specifies the pointer to the region of a key.  `ksiz'
              specifies the size of the region of the key.  If it is negative,
              the size is assigned with `strlen(kbuf)'.  `vbuf' specifies the
              pointer to the region of a value.  `vsiz' specifies the size of
              the region of the value.  If it is negative, the size is
              assigned with `strlen(vbuf)'.  `dmode' specifies behavior when
              the key overlaps, by the following values: `CR_DOVER', which
              means the specified value overwrites the existing one,
              `CR_DKEEP', which means the existing value is kept, `CR_DCAT',
              which means the specified value is concatenated at the end of
              the existing value.  If successful, the return value is true,
              else, it is false.

       The function `crout' is used in order to delete a record.

       int crout(CURIA *curia, const char *kbuf, int ksiz);
              `curia' specifies a database handle connected as a writer.
              `kbuf' specifies the pointer to the region of a key.  `ksiz'
              specifies the size of the region of the key.  If it is negative,
              the size is assigned with `strlen(kbuf)'.  If successful, the
              return value is true, else, it is false.  false is returned when
              no record corresponds to the specified key.

       The function `crget' is used in order to retrieve a record.

       char *crget(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, int *sp);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  `start' specifies the offset address of
              the beginning of the region of the value to be read.  `max'
              specifies the max size to be read.  If it is negative, the size
              to read is unlimited.  `sp' specifies the pointer to a variable
              to which the size of the region of the return value is assigned.
              If it is `NULL', it is not used.  If successful, the return
              value is the pointer to the region of the value of the
              corresponding record, else, it is `NULL'.  `NULL' is returned
              when no record corresponds to the specified key or the size of
              the value of the corresponding record is less than `start'.
              Because an additional zero code is appended at the end of the
              region of the return value, the return value can be treated as a
              character string.  Because the region of the return value is
              allocated with the `malloc' call, it should be released with the
              `free' call if it is no longer in use.

       The function `crgetwb' is used in order to retrieve a record and write
       the value into a buffer.

       int crgetwb(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, char *vbuf);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  `start' specifies the offset address of
              the beginning of the region of the value to be read.  `max'
              specifies the max size to be read.  It shuld be equal to or less
              than the size of the writing buffer.  `vbuf' specifies the
              pointer to a buffer into which the value of the corresponding
              record is written.  If successful, the return value is the size
              of the written data, else, it is -1.  -1 is returned when no
              record corresponds to the specified key or the size of the value
              of the corresponding record is less than `start'.  Note that no
              additional zero code is appended at the end of the region of the
              writing buffer.

       The function `crvsiz' is used in order to get the size of the value of
       a record.

       int crvsiz(CURIA *curia, const char *kbuf, int ksiz);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  If successful, the return value is the
              size of the value of the corresponding record, else, it is -1.
              Because this function does not read the entity of a record, it
              is faster than `crget'.

       The function `criterinit' is used in order to initialize the iterator
       of a database handle.

       int criterinit(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is true, else, it is false.  The iterator is used in order
              to access the key of every record stored in a database.

       The function `criternext' is used in order to get the next key of the
       iterator.

       char *criternext(CURIA *curia, int *sp);
              `curia' specifies a database handle.  `sp' specifies the pointer
              to a variable to which the size of the region of the return
              value is assigned.  If it is `NULL', it is not used.  If
              successful, the return value is the pointer to the region of the
              next key, else, it is `NULL'.  `NULL' is returned when no record
              is to be get out of the iterator.  Because an additional zero
              code is appended at the end of the region of the return value,
              the return value can be treated as a character string.  Because
              the region of the return value is allocated with the `malloc'
              call, it should be released with the `free' call if it is no
              longer in use.  It is possible to access every record by
              iteration of calling this function.  However, it is not assured
              if updating the database is occurred while the iteration.
              Besides, the order of this traversal access method is arbitrary,
              so it is not assured that the order of storing matches the one
              of the traversal access.

       The function `crsetalign' is used in order to set alignment of a
       database handle.

       int crsetalign(CURIA *curia, int align);
              `curia' specifies a database handle connected as a writer.
              `align' specifies the size of alignment.  If successful, the
              return value is true, else, it is false.  If alignment is set to
              a database, the efficiency of overwriting values is improved.
              The size of alignment is suggested to be average size of the
              values of the records to be stored.  If alignment is positive,
              padding whose size is multiple number of the alignment is
              placed.  If alignment is negative, as `vsiz' is the size of a
              value, the size of padding is calculated with `(vsiz / pow(2,
              abs(align) - 1))'.  Because alignment setting is not saved in a
              database, you should specify alignment every opening a database.

       The function `crsetfbpsiz' is used in order to set the size of the free
       block pool of a database handle.

       int crsetfbpsiz(CURIA *curia, int size);
              `curia' specifies a database handle connected as a writer.
              `size' specifies the size of the free block pool of a database.
              If successful, the return value is true, else, it is false.  The
              default size of the free block pool is 16.  If the size is
              greater, the space efficiency of overwriting values is improved
              with the time efficiency sacrificed.

       The function `crsync' is used in order to synchronize updating contents
       with the files and the devices.

       int crsync(CURIA *curia);
              `curia' specifies a database handle connected as a writer.  If
              successful, the return value is true, else, it is false.  This
              function is useful when another process uses the connected
              database directory.

       The function `croptimize' is used in order to optimize a database.

       int croptimize(CURIA *curia, int bnum);
              `curia' specifies a database handle connected as a writer.
              `bnum' specifies the number of the elements of each bucket
              array.  If it is not more than 0, the default value is
              specified.  In an alternating succession of deleting and storing
              with overwrite or concatenate, dispensable regions accumulate.
              This function is useful to do away with them.

       The function `crname' is used in order to get the name of a database.

       char *crname(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the pointer to the region of the name of the database,
              else, it is `NULL'.  Because the region of the return value is
              allocated with the `malloc' call, it should be released with the
              `free' call if it is no longer in use.

       The function `crfsiz' is used in order to get the total size of
       database files.

       int crfsiz(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the total size of the database files, else, it is -1.
              If the total size is more than 2GB, the return value overflows.

       The function `crfsizd' is used in order to get the total size of
       database files as double-precision floating-point number.

       double crfsizd(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the total size of the database files, else, it is -1.0.

       The function `crbnum' is used in order to get the total number of the
       elements of each bucket array.

       int crbnum(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the total number of the elements of each bucket array,
              else, it is -1.

       The function `crbusenum' is used in order to get the total number of
       the used elements of each bucket array.

       int crbusenum(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the total number of the used elements of each bucket
              array, else, it is -1.  This function is inefficient because it
              accesses all elements of each bucket array.

       The function `crrnum' is used in order to get the number of the records
       stored in a database.

       int crrnum(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the number of the records stored in the database, else,
              it is -1.

       The function `crwritable' is used in order to check whether a database
       handle is a writer or not.

       int crwritable(CURIA *curia);
              `curia' specifies a database handle.  The return value is true
              if the handle is a writer, false if not.

       The function `crfatalerror' is used in order to check whether a
       database has a fatal error or not.

       int crfatalerror(CURIA *curia);
              `curia' specifies a database handle.  The return value is true
              if the database has a fatal error, false if not.

       The function `crinode' is used in order to get the inode number of a
       database directory.

       int crinode(CURIA *curia);
              `curia' specifies a database handle.  The return value is the
              inode number of the database directory.

       The function `crmtime' is used in order to get the last modified time
       of a database.

       time_t crmtime(CURIA *curia);
              `curia' specifies a database handle.  The return value is the
              last modified time of the database.

       The function `crremove' is used in order to remove a database
       directory.

       int crremove(const char *name);
              `name' specifies the name of a database directory.  If
              successful, the return value is true, else, it is false.

       The function `crrepair' is used in order to repair a broken database
       directory.

       int crrepair(const char *name);
              `name' specifies the name of a database directory.  If
              successful, the return value is true, else, it is false.  There
              is no guarantee that all records in a repaired database
              directory correspond to the original or expected state.

       The function `crexportdb' is used in order to dump all records as
       endian independent data.

       int crexportdb(CURIA *curia, const char *name);
              `curia' specifies a database handle.  `name' specifies the name
              of an output directory.  If successful, the return value is
              true, else, it is false.  Note that large objects are ignored.

       The function `crimportdb' is used in order to load all records from
       endian independent data.

       int crimportdb(CURIA *curia, const char *name);
              `curia' specifies a database handle connected as a writer.  The
              database of the handle must be empty.  `name' specifies the name
              of an input directory.  If successful, the return value is true,
              else, it is false.  Note that large objects are ignored.

       The function `crsnaffle' is used in order to retrieve a record directly
       from a database directory.

       char *crsnaffle(const char *name, const char *kbuf, int ksiz, int *sp);
              `name' specifies the name of a database directory.  `kbuf'
              specifies the pointer to the region of a key.  `ksiz' specifies
              the size of the region of the key.  If it is negative, the size
              is assigned with `strlen(kbuf)'.  `sp' specifies the pointer to
              a variable to which the size of the region of the return value
              is assigned.  If it is `NULL', it is not used.  If successful,
              the return value is the pointer to the region of the value of
              the corresponding record, else, it is `NULL'.  `NULL' is
              returned when no record corresponds to the specified key.
              Because an additional zero code is appended at the end of the
              region of the return value, the return value can be treated as a
              character string.  Because the region of the return value is
              allocated with the `malloc' call, it should be released with the
              `free' call if it is no longer in use.  Although this function
              can be used even while the database directory is locked by
              another process, it is not assured that recent updated is
              reflected.

       The function `crputlob' is used in order to store a large object.

       int crputlob(CURIA *curia, const char *kbuf, int ksiz, const char
       *vbuf, int vsiz, int dmode);
              `curia' specifies a database handle connected as a writer.
              `kbuf' specifies the pointer to the region of a key.  `ksiz'
              specifies the size of the region of the key.  If it is negative,
              the size is assigned with `strlen(kbuf)'.  `vbuf' specifies the
              pointer to the region of a value.  `vsiz' specifies the size of
              the region of the value.  If it is negative, the size is
              assigned with `strlen(vbuf)'.  `dmode' specifies behavior when
              the key overlaps, by the following values: `CR_DOVER', which
              means the specified value overwrites the existing one,
              `CR_DKEEP', which means the existing value is kept, `CR_DCAT',
              which means the specified value is concatenated at the end of
              the existing value.  If successful, the return value is true,
              else, it is false.

       The function `croutlob' is used in order to delete a large object.

       int croutlob(CURIA *curia, const char *kbuf, int ksiz);
              `curia' specifies a database handle connected as a writer.
              `kbuf' specifies the pointer to the region of a key.  `ksiz'
              specifies the size of the region of the key.  If it is negative,
              the size is assigned with `strlen(kbuf)'.  If successful, the
              return value is true, else, it is false.  false is returned when
              no large object corresponds to the specified key.

       The function `crgetlob' is used in order to retrieve a large object.

       char *crgetlob(CURIA *curia, const char *kbuf, int ksiz, int start, int
       max, int *sp);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  `start' specifies the offset address of
              the beginning of the region of the value to be read.  `max'
              specifies the max size to be read.  If it is negative, the size
              to read is unlimited.  `sp' specifies the pointer to a variable
              to which the size of the region of the return value is assigned.
              If it is `NULL', it is not used.  If successful, the return
              value is the pointer to the region of the value of the
              corresponding large object, else, it is `NULL'.  `NULL' is
              returned when no large object corresponds to the specified key
              or the size of the value of the corresponding large object is
              less than `start'.  Because an additional zero code is appended
              at the end of the region of the return value, the return value
              can be treated as a character string.  Because the region of the
              return value is allocated with the `malloc' call, it should be
              released with the `free' call if it is no longer in use.

       The function `crgetlobfd' is used in order to get the file descriptor
       of a large object.

       int crgetlobfd(CURIA *curia, const char *kbuf, int ksiz);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  If successful, the return value is the
              file descriptor of the corresponding large object, else, it is
              -1.  -1 is returned when no large object corresponds to the
              specified key.  The returned file descriptor is opened with the
              `open' call.  If the database handle was opened as a writer, the
              descriptor is writable (O_RDWR), else, it is not writable
              (O_RDONLY).  The descriptor should be closed with the `close'
              call if it is no longer in use.

       The function `crvsizlob' is used in order to get the size of the value
       of a large object.

       int crvsizlob(CURIA *curia, const char *kbuf, int ksiz);
              `curia' specifies a database handle.  `kbuf' specifies the
              pointer to the region of a key.  `ksiz' specifies the size of
              the region of the key.  If it is negative, the size is assigned
              with `strlen(kbuf)'.  If successful, the return value is the
              size of the value of the corresponding large object, else, it is
              -1.  Because this function does not read the entity of a large
              object, it is faster than `crgetlob'.

       The function `crrnumlob' is used in order to get the number of the
       large objects stored in a database.

       int crrnumlob(CURIA *curia);
              `curia' specifies a database handle.  If successful, the return
              value is the number of the large objects stored in the database,
              else, it is -1.

       If QDBM was built with POSIX thread enabled, the global variable
       `dpecode' is treated as thread specific data, and functions of Curia
       are reentrant.  In that case, they are thread-safe as long as a handle
       is not accessed by threads at the same time, on the assumption that
       `errno', `malloc', and so on are thread-safe.


SEE ALSO
       qdbm(3), depot(3), relic(3), hovel(3), cabin(3), villa(3), odeum(3),
       ndbm(3), gdbm(3)



Man Page                          2004-04-22                          CURIA(3)
