#include <db.h> int DB_ENV->close(DB_ENV *dbenv, u_int32_t flags);
The DB_ENV->close() method closes the Berkeley DB environment,
freeing any allocated resources and closing any underlying subsystems.
The DB_ENV handle should not be closed while any other handle that refers to it is not yet closed; for example, database environment handles must not be closed while database handles remain open, or transactions in the environment have not yet been committed or aborted. Specifically, this includes the DB, DBcursor, DB_TXN, DB_LOGC and DB_MPOOLFILE handles.
Where the environment was initialized with the
DB_INIT_LOCK flag,
calling DB_ENV->close() does not release any locks still held by the
closing process, providing functionality for long-lived locks.
Processes that want to have all their locks released can do so by
issuing the appropriate DB_ENV->lock_vec() call.
Where the environment was initialized with the
DB_INIT_MPOOL flag,
calling DB_ENV->close() implies calls to
DB_MPOOLFILE->close() for any
remaining open files in the memory pool that were returned to this
process by calls to DB_MPOOLFILE->open(). It does
not imply a call to DB_MPOOLFILE->sync() for those
files.
Where the environment was initialized with the
DB_INIT_TXN flag,
calling DB_ENV->close() aborts any unresolved transactions.
Applications should not depend on this behavior for transactions
involving Berkeley DB databases; all such transactions should be
explicitly resolved. The problem with depending on this semantic is
that aborting an unresolved transaction involving database operations
requires a database handle. Because the database handles should have
been closed before calling DB_ENV->close(), it will not be possible
to abort the transaction, and recovery will have to be run on the
Berkeley DB environment before further operations are done.
Where log cursors were created using the
DB_ENV->log_cursor() method,
calling DB_ENV->close() does not imply closing those cursors.
In multithreaded applications, only a single thread may call the
DB_ENV->close() method.
After DB_ENV->close() has been called, regardless of its return, the
Berkeley DB environment handle may not be accessed again.
The DB_ENV->close()
method returns a non-zero error value on failure and 0 on success.