DbEnv::set_app_dispatch(int (*)(DbEnv *dbenv,
Dbt *log_rec, DbLsn *lsn, db_recops op));
Set the application's method to be called during transaction abort
and recovery. This method must return 0 on success and either
errno or a value outside of the Berkeley DB error name space on
failure. It takes four arguments:
- A Berkeley DB environment.
- A log record.
- A log sequence number.
- One of the following values:
- The log is being read backward to determine which transactions have been
committed and to abort those operations that were not; undo the operation
described by the log record.
- The log is being played forward; redo the operation described by the log
- The log is being read backward during a transaction abort; undo the
operation described by the log record.
- The log is being applied on a replica site; redo the operation
described by the log record.
- The log is being printed for debugging purposes; print the contents of
this log record in the desired format.
The DB_TXN_FORWARD_ROLL and 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_TXN_APPLY operations
should also perform appropriate locking. The macro DB_REDO(op) checks
that the operation is one of DB_TXN_FORWARD_ROLL or
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_TXN_BACKWARD_ROLL or DB_TXN_ABORT.
The DbEnv::set_app_dispatch method configures operations performed using the specified
DbEnv handle, not all operations performed on the underlying
The DbEnv::set_app_dispatch interface may not be called after the DbEnv::open
interface is called.
If the database environment already exists when
DbEnv::open is called, the information specified to DbEnv::set_app_dispatch
must be consistent with the existing environment or corruption can
The DbEnv::set_app_dispatch 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 DbEnv::set_app_dispatch method may fail and throw an exception or return a non-zero error for the following conditions:
- An invalid flag value or parameter was specified.
Called after DbEnv::open was called.
The DbEnv::set_app_dispatch method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the DbEnv::set_app_dispatch method may fail and
either return DB_RUNRECOVERY or throw a
in which case all subsequent Berkeley DB calls will fail in the same way.
Transaction Subsystem and Related Methods
Copyright Sleepycat Software