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Berkeley DB: DB_ENV->close
DB_ENV->close
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#include <db.h>
int
DB_ENV->close(DB_ENV *dbenv, u_int32_t flags);
Description: DB_ENV->close
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 DB, DBC, 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
DB_ENV->close.
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.
Parameters
- flags
- The flags parameter is currently unused, and must be set to 0.
Class
DB_ENV
See Also
Database Environments and Related Methods
Copyright (c) 1996-2004 Sleepycat Software, Inc. - All rights reserved.
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