#include <db_cxx.h>

int
DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags);

Description

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

The flags value must be set to 0 or the following value:

DB_STAT_CLEAR

Reset statistics after returning their values.

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_nrestores;

The number of transactions that have been restored.

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

See Also