#include <db_cxx.h>

int
DbEnv::failchk(u_int32_t flags);

The DbEnv::failchk method checks for threads of control (either a true thread or a process) that have exited while manipulating Berkeley DB library data structures, while holding a logical database lock, or with an unresolved transaction (that is, a transaction that was never aborted or committed). For more information, see Architecting Data Store and Concurrent Data Store applications, and Architecting Transactional Data Store applications.

The DbEnv::failchk method is based on the "thread_id" and "is_alive" functions specified to the DbEnv::set_thread_id method. Applications calling the DbEnv::failchk method must have already called the DbEnv::set_isalive method, on the same DbEnv, and must have configured their database environment using the DbEnv::set_thread_count method.

If DbEnv::failchk determines a thread of control exited while holding database read locks, it will release those locks. If DbEnv::failchk determines a thread of control exited with an unresolved transaction, the transaction will be aborted. In either of these cases, DbEnv::failchk will return 0 and the application may continue to use the database environment.

In either of these cases, the DbEnv::failchk method will also report the process and thread IDs associated with any released locks or aborted transactions. The information is printed to a specified output channel (see the DbEnv::set_msgfile method for more information), or passed to an application callback function (see the DbEnv::set_msgcall method for more information).

If DbEnv::failchk determines a thread of control has exited such that database environment recovery is required, it will return DB_RUNRECOVERY. In this case, the application should not continue to use the database environment. For a further description as to the actions the application should take when this failure occurs, see Handling failure in Data Store and Concurrent Data Store applications, and Handling failure in Transactional Data Store applications.

The DbEnv::failchk method may not be called before the DbEnv::open method is called.

The DbEnv::failchk 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 flags parameter is currently unused, and must be set to 0.

The DbEnv::failchk method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

• An invalid flag value or parameter was specified.