#include <db_cxx.h>
DB_ENV->set_backup_callbacks(
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 DbEnv::set_backup_callbacks() method
configures three callback functions which can be used by the
DbEnv::backup()
or
DbEnv::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
DbEnv::backup()
or
DbEnv::dbbackup()
methods.
The DbEnv::set_backup_callbacks() method
configures operations performed using the specified
DbEnv handle, not all operations
performed on the underlying database environment.
The DbEnv::set_backup_callbacks() method may
be called at any time during the life of the application.
The DbEnv::set_backup_callbacks()
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
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.
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.
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.