DB_ENV->set_backup_callbacks()

#include <db.h>
 
DB_ENV->set_backup_callbacks(DB_ENV, 
        int (*open_func)(DB_ENV *, const char *dbname, 
                         const char *target, void **handle),
        int (*write_func)(DB_ENV *, u_int32_t offset_gbytes, 
                          u_int32_t offset_bytes, u_int32_t size, 
                          u_int8_t *buf, void *handle),
        int (*close_func)(DB_ENV *, const char *dbname, void *handle));  

The DB_ENV->set_backup_callbacks() method configures three callback functions which can be used by the DB_ENV->backup() or DB_ENV->dbbackup() methods to override their default behavior. If one callback is configured, then all three callbacks must be configured. These callbacks are required if the target parameter is set to NULL for the DB_ENV->backup() or DB_ENV->dbbackup() methods.

The DB_ENV->set_backup_callbacks() method configures operations performed using the specified DB_ENV handle, not all operations performed on the underlying database environment.

The DB_ENV->set_backup_callbacks() method may be called at any time during the life of the application.

The DB_ENV->set_backup_callbacks() method returns a non-zero error value on failure and 0 on success.

Parameters

open_func

The open_func parameter is the function used when a target location is opened during a backup. This function should do whatever is necessary to prepare the backup destination for writing the data.

This function takes four parameters:

• dbenv

  The dbenv parameter is the enclosing database environment handle.

• dbname

  The dbname parameter is the name of the database being backed up.

• target

  The target parameter is the backup's directory destination.

• handle

  The handle parameter references the handle (usually a file handle) to which the backup will be written.

write_func

The write_func parameter is the function used to write data during a backup. The function takes six parameters:

• dbenv

  The dbenv parameter is the enclosing database environment handle.

• offset_gbytes

  The offset_gbytes parameter specifies the number of gigabytes into the output handle where the data can should be written. This value, plus the value specified on offset_bytes, indicates the offset within the output handle where the backup should begin.

• offset_bytes

  The offset_bytes parameter specifies the number of bytes into the output handle where the data can be located. This value, plus the value specified on offset_gbytes, indicates the offset within the output handle where the backup should begin.

• size

  The size parameter specifies the number of bytes to back up from the buffer.

• buf

  The buf parameter is the buffer which contains the data to be backed up.

• handle

  The handle parameter references the handle (usually a file handle) to which the backup will be written.

close_func

The close_func parameter is the function used when ending a backup and closing a backup target. The function takes three parameters:

• dbenv

  The dbenv parameter is the enclosing database environment handle.

• dbname

  The dbname parameter is the name of the database that has now been backed up.

• handle

  The handle parameter references the handle (usually a file handle) to which the backup was written, and which now must be closed or otherwise discarded.

Class

DB_ENV

See Also

Database Environments and Related Methods, DB_ENV->get_backup_callbacks(), DB_ENV->backup(), and DB_ENV->dbbackup().