#include <db.h>
void
DB_ENV->set_msgcall(DB_ENV *dbenv,
void (*db_msgcall_fcn)(const DB_ENV *dbenv,
const char *msgpfx,
const char *msg));
There are interfaces in the Berkeley DB library which either directly output informational messages or statistical information, or configure the library to output such messages when performing other operations, for example, DB_ENV->set_verbose() and DB_ENV->stat_print() .
The DB_ENV->set_msgcall() and
DB->set_msgcall()
methods are used to pass these messages to the application, and Berkeley DB will call
db_msgcall_fcn with each message. It
is up to the db_msgcall_fcn function
to display the message in an appropriate manner.
Setting db_msgcall_fcn to NULL unconfigures the callback interface.
Alternatively, you can use the DB->set_msgfile() or DB->set_msgfile() methods to display the messages via a C library FILE *.
The DB_ENV->set_msgcall() method configures operations performed
using the specified DB_ENV handle, not all
operations performed on the underlying database environment.
The DB_ENV->set_msgcall() method may be called at any time during the
life of the application.
Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined.
The db_msgcall_fcn parameter is the application-specified message reporting function. The function takes three parameters:
dbenv
The dbenv parameter is the enclosing database environment.
msgpfx
The msgpfx parameter is the message prefix string that appears before informational messages. This value is the environmental default, and can be changed at any time using DB_ENV->set_msgpfx() or DB->set_msgpfx() .
msg
The msg parameter is the message string.