,I+Berkeley DB: DbTxnMgr::begin[P

DbTxnMgr::begin





#include <db_cxx.h>

int)DbTxnMgr::begin(DbTxn *pid, DbTxn **tid);





Description



;The DbTxnMgr::begin method creates a new transaction in thetransaction manager,Icopying a pointer to a DB_TXN that uniquely identifies it into the memoryreferenced by tid.

FNote: transactions may not span threads, i.e., each transactionGmust begin and end in the same thread, and each transaction may only beused by a single thread.

FNote: transactions may not span cursors, i.e., each transaction$may only be used by a single cursor.

CNote: transactions may not currently be nested. In a futureHrevision of Berkeley DB, if the pid argument is non-NULL, the newHtransaction will be a nested transaction, with the transaction indicatedby pid as its parent.

The DbTxnMgr::begin>method either returns errno or throws an exception that:encapsulates an errno on failure, and 0 on success.



Errors

VIf a fatal error occurs in Berkeley DB, the DbTxnMgr::begin method may fail and eitherIreturn DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY,Gat which point all subsequent database calls will also fail in the sameFway. Methods marked as returning errno will, by default, throwHan exception that encapsulates the error information. The default error\behavior can be changed, see DbException.

The DbTxnMgr::begin&method may fail and throw an exceptionKfor any of the errors specified for the following Berkeley DB and C library functions: abort(3), fcntl(3), fflush(3), fprintf(3),free(3), fsync(3), getpid(3),6DbLog::put, lseek(3), memset(3),mmap(3), munmap(3), shmat(3), shmdt(3), strerror(3), vfprintf(3), vsnprintf(3),and write(3).

In addition, the DbTxnMgr::begin&method may fail and throw an exceptionor return errnofor the following conditions:

P

ENOSPC
The maximum number of concurrent transactions has been reached.




Class

8DbTxnMgr



See Also

DbTxnMgr::begin,JDbTxnMgr::checkpoint,@DbTxnMgr::close,>DbTxnMgr::open,=DbTxnMgr::statandBDbTxnMgr::unlink.
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