m4_comment([$Id: db_set_h_hash.so,v 10.40 2004/08/13 03:38:56 bostic Exp $])

define(M4PAGELOCAL, dbh_set_h_hash)
include(m4/m4.seealso)

m4_pf_header(m4_ref(dbh_set_h_hash),
ifelse(M4API, C_API, [dnl
int
DB-__GT__set_h_hash(DB *db,
    u_int32_t (*h_hash_fcn)(DB *, const void *bytes, u_int32_t length));
])
ifelse(M4API, CXX_API, [dnl
extern "C" {
    typedef u_int32_t (*h_hash_fcn_type)
	(DB *, const void *bytes, u_int32_t length);
};
int
Db::set_h_hash(h_hash_fcn_type h_hash_fcn);
]))

m4_p([dnl
Set a user-defined hash function; if no hash function is specified, a
default hash function is used.  Because no hash function performs
equally well on all possible data, the user may find that the built-in
hash function performs poorly with a particular data set.])

m4_scope_dbh(dbh_set_h_hash)

m4_when_dbopen(dbh_set_h_hash, corrupt)

m4_return(dbh_set_h_hash, std)

m4_parambegin
m4_param(h_hash_fcn, [dnl
The m4_arg(h_hash_fcn) parameter is the application-specified hash function.
m4_p([dnl
Application-specified hash functions take a pointer to a byte string and
a length as parameters, and return a value of type m4_bold(u_int32_t).
The hash function must handle any key values used by the application
(possibly including zero-length keys).])])
m4_paramend

m4_err(dbh_set_h_hash,
einval, [the method was called after m4_ref(dbh_open) was called; the
specified hash function differs from the hash function with which the
database was created])

m4_seealso(Db)
m4_page_footer