cdbr(3) - NetBSD Manual Pages

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CDBR(3)                 NetBSD Library Functions Manual                CDBR(3)


NAME

     cdbr, cdbr_open, cdbr_open_mem, cdbr_entries, cdbr_get, cdbr_find,
     cdbr_close -- constant database access methods


SYNOPSIS

     struct cdbr *
     cdbr_open(const char *path, int flags);

     struct cdbr *
     cdbr_open_mem(void *base, size_t size, int flags,
         void (*unmap)(void *, void *, size_t), void *cookie);

     uint32_t
     cdbr_entries(struct cdbr *cdbr);

     int
     cdbr_get(struct cdbr *cdbr, uint32_t index, const void **data,
         size_t *datalen);

     int
     cdbr_find(struct cdbr *cdbr, const void *key, size_t keylen,
         const void **data, size_t *datalen);

     void
     cdbr_close(struct cdbr *cdbr);


DESCRIPTION

     The cdbr library provides a space efficient (key,value) database based on
     perfect hashing.

     A cdb database is opened for reading by calling cdbr_open().  The only
     supported value for flags is CDBR_DEFAULT.  The function returns a handle
     to pass to the other functions.  The database is closed by invoking
     cdbr_close().  All resources associated with the handle are freed and the
     memory returned by cdbr_get() and cdbr_find() is invalidated.
     cdbr_open_mem() works like cdbr_open(), but takes a memory reference to
     the content of the database file.  If unmap is not NULL, it is called by
     cdbr_close() with cookie, base and size as arguments.  It is not called
     by cdbr_open_mem() on error.

     The number of records in the database can be obtained by calling
     cdbr_entries().  Records can be obtained by record number using
     cdbr_get() or by key using cdbr_find().  Both functions return 0 on suc-
     cess and update data and datalen accordingly.  The location *data remains
     valid until cdbr_close() is called.  It is the responsibility of the
     caller of cdbr_find() to ensure that the key matches the returned data.
     The function returns the only possible match, but the database doesn't
     store the keys to minimize overhead.


SEE ALSO

     nbperf(1), cdbw(3), db(3), cdb(5)


HISTORY

     Support for the cdb format first appeared in NetBSD 6.0.


AUTHORS

     The cdbr and cdbw functions have been written by Joerg Sonnenberger
     <joerg@NetBSD.org>.

NetBSD 10.1                    December 1, 2018                    NetBSD 10.1