DbEnv::txn_stat

APIRef

#include <db_cxx.h>

int DbEnv::txn_stat(DB_TXN_STAT **statp);

Description

The DbEnv::txn_stat method creates a statistical structure and copies a pointer to it into a user-specified memory location.

Statistical structures are created in allocated memory. If application-specific allocation routines have been declared (see DbEnv::set_alloc for more information), they are used to allocate the memory; otherwise, the library function malloc(3) is used. The caller is responsible for deallocating the memory. To deallocate the memory, free the memory reference; references inside the returned memory need not be individually freed.

The transaction region statistics are stored in a structure of type DB_TXN_STAT. The following DB_TXN_STAT fields will be filled in:

DbLsn st_last_ckp;
The LSN of the last checkpoint.
DbLsn st_pending_ckp;
The LSN of any checkpoint that is currently in progress. If st_pending_ckp is the same as st_last_ckp there is no checkpoint in progress.
time_t st_time_ckp;
The time the last completed checkpoint finished (as the number of seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX) time interface).
u_int32_t st_last_txnid;
The last transaction ID allocated.
u_int32_t st_maxtxns;
The maximum number of active transactions possible.
u_int32_t st_nactive;
The number of transactions that are currently active.
u_int32_t st_maxnactive;
The maximum number of active transactions at any one time.
u_int32_t st_nbegins;
The number of transactions that have begun.
u_int32_t st_naborts;
The number of transactions that have aborted.
u_int32_t st_ncommits;
The number of transactions that have committed.
u_int32_t st_regsize;
The size of the region.
u_int32_t st_region_wait;
The number of times that a thread of control was forced to wait before obtaining the region lock.
u_int32_t st_region_nowait;
The number of times that a thread of control was able to obtain the region lock without waiting.
DB_TXN_ACTIVE * st_txnarray;
A pointer to an array of st_nactive DB_TXN_ACTIVE structures, describing the currently active transactions. The following fields of the DB_TXN_ACTIVE structure will be filled in:

u_int32_t txnid;
The transaction ID of the transaction.
u_int32_t parentid;
The transaction ID of the parent transaction (or 0, if no parent).
DbLsn lsn;
The log sequence number of the transaction-begin record.

The DbEnv::txn_stat 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.

Errors

The DbEnv::txn_stat method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::txn_stat method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

Class

DbEnv, DbTxn

See Also

DbEnv::set_tx_max, DbEnv::set_tx_recover, DbEnv::set_tx_timestamp, DbTxn::abort, DbEnv::txn_begin, DbEnv::txn_checkpoint, DbTxn::commit, DbTxn::discard, DbTxn::id, DbTxn::prepare, DbEnv::txn_recover, and DbEnv::txn_stat.

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