Errors can occur in the Berkeley DB library where the only solution is to shut
down the application and run recovery. (For example, if Berkeley DB is unable
to write log records to disk because there is insufficient disk space.)
In these cases, when the C++ error model has been configured so that the
individual Berkeley DB methods return error codes (see DbException for
more information), the value DB_RUNRECOVERY is returned by Berkeley DB
methods.
In these cases, it is also often simpler to shut down the application when
such errors occur rather than attempting to gracefully return up the stack.
The DbEnv::set_paniccall method is used to specify a method to be called when
DB_RUNRECOVERY is about to be returned from a Berkeley DB method. When
called, the dbenv argument will be a reference to the current
environment, and the errval argument is the error value that would
have been returned to the calling method.
The DbEnv::set_paniccall interface may be used to configure Berkeley DB at any time
during the life of the application.
The DbEnv::set_paniccall 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.