Berkeley DB: DbTxnMgr::checkpoint
Полезная информация

DbTxnMgr::checkpoint


#include <db_cxx.h>

int DbTxnMgr::checkpoint(u_int32_t kbyte, u_int32_t min) const;

Description

The DbTxnMgr::checkpoint method flushes the underlying memory pool, writes a checkpoint record to the log and then flushes the log.

If either kbyte or min is non-zero, the checkpoint is only done if more than min minutes have passed since the last checkpoint, or if more than kbyte kilobytes of log data have been written since the last checkpoint.

The DbTxnMgr::checkpoint method either returns errno or throws an exception that encapsulates an errno on failure, and 0 on success, and DB_INCOMPLETE if there were pages that needed to be written but that DbMpool::sync was unable to write immediately. In this case, the DbTxnMgr::checkpoint call should be retried.

The DbTxnMgr::checkpoint method is the underlying method used by the db_checkpoint utility. See the db_checkpoint utility source code for an example of using DbTxnMgr::checkpoint in a POSIX 1003.1 environment.

Errors

If a fatal error occurs in Berkeley DB, the DbTxnMgr::checkpoint method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, at which point all subsequent database calls will also fail in the same way. Methods marked as returning errno will, by default, throw an exception that encapsulates the error information. The default error behavior can be changed, see DbException.

The DbTxnMgr::checkpoint method may fail and throw an exception for any of the errors specified for the following Berkeley DB and C library functions: abort(3), fcntl(3), fflush(3), fprintf(3), free(3), getpid(3), DbLog::compare, DbLog::put, malloc(3), memcpy(3), DbMpool::sync, memset(3), strerror(3), time(3), vfprintf(3), and vsnprintf(3).

In addition, the DbTxnMgr::checkpoint method may fail and throw an exception or return errno for the following conditions:

EINVAL
An invalid flag value or parameter was specified.

Class

DbTxnMgr

See Also

DbTxnMgr::begin, DbTxnMgr::checkpoint, DbTxnMgr::close, DbTxnMgr::open, DbTxnMgr::stat and DbTxnMgr::unlink.