com.sleepycat.db
Interface DbAppDispatch

public interface DbAppDispatch

An interface specifying a recovery function, which recovers application-specific actions.

Method Summary

int	appDispatch(DbEnv dbenv, Dbt log_rec, DbLsn lsn, int op) The DbAppDispatch interface is used by the DbEnv.setAppDispatch method.

Method Detail

appDispatch

public int appDispatch(DbEnv dbenv,
                       Dbt log_rec,
                       DbLsn lsn,
                       int op)

The DbAppDispatch interface is used by the DbEnv.setAppDispatch method. This interface defines the application-specific function to be called during transaction abort and recovery.

The Db.DB_TXN_FORWARD_ROLL and Db.DB_TXN_APPLY operations frequently imply the same actions, redoing changes that appear in the log record, although if a recovery function is to be used on a replication client where reads may be taking place concurrently with the processing of incoming messages, Db.DB_TXN_APPLY operations should also perform appropriate locking. The macro DB_REDO(op) checks that the operation is one of Db.DB_TXN_FORWARD_ROLL or Db.DB_TXN_APPLY, and should be used in the recovery code to refer to the conditions under which operations should be redone. Similarly, the macro DB_UNDO(op) checks if the operation is one of Db.DB_TXN_BACKWARD_ROLL or Db.DB_TXN_ABORT.

Parameters:

dbenv - the enclosing database environment handle.

log_rec - a log record.

lsn - a log sequence number.

op - one of the following values:

Returns:

The function must return 0 on success and either errno or a value outside of the Berkeley DB error name space on failure.