#include <db_cxx.h> int DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags);
The DbEnv::txn_stat() method returns the transaction subsystem
statistics.
The DbEnv::txn_stat() method creates a statistical structure of type
DB_TXN_STAT and copies a pointer to it into a user-specified memory
location.
Statistical structures are stored 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 standard C library 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 following DB_TXN_STAT fields will be filled in:
DB_LSN st_last_ckp;
The LSN of the last checkpoint.
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 function).
u_int32_t st_last_txnid;
The last transaction ID allocated.
u_int32_t st_maxtxns;
The maximum number of active transactions configured.
u_int32_t st_nactive;
The number of transactions that are currently active.
u_int32_t st_nsnapshot;
The number of transactions on the snapshot list. These are transactions which modified a database opened with DB_MULTIVERSION, and which have committed or aborted, but the copies of pages they created are still in the cache.
u_int32_t st_maxnactive;
The maximum number of active transactions at any one time.
u_int32_t st_maxnsnapshot;
The maximum number of transactions on the snapshot list at any one time.
uintmax_t st_nbegins;
The number of transactions that have begun.
uintmax_t st_naborts;
The number of transactions that have aborted.
uintmax_t st_ncommits;
The number of transactions that have committed.
u_int32_t st_nrestores;
The number of transactions that have been restored.
roff_t st_regsize;
The size of the transaction region, in bytes.
uintmax_t st_region_wait;
The number of times that a thread of control was forced to wait before obtaining the transaction region mutex.
uintmax_t st_region_nowait;
The number of times that a thread of control was able to obtain the transaction region mutex 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).
pid_t pid;
The process ID of the originator of the transaction.
db_threadid_t tid;
The thread of control ID of the originator of the transaction.
DB_LSN lsn;
The current log sequence number when the transaction was begun.
DB_LSN read_lsn;
The log sequence number of reads for snapshot transactions.
u_int32_t mvcc_ref;
The number of buffer copies created by this transaction that remain in cache.
u_int32_t status;
One of the following list of constants: TXN_ABORTED, TXN_COMMITTED, TXN_PREPARED, TXN_RUNNING.
u_int8_t gid[DB_GID_SIZE];
If the transaction was prepared using DbTxn::prepare(), then gid contains the transaction's Global ID. Otherwise, gid's contents are undefined.
char name[];
If a name was specified for the transaction, up to the first 50 bytes of that name, followed by a nul termination byte.
The DbEnv::txn_stat() method may not be called before the
DbEnv::open() method is called.
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.
The flags parameter must be set to 0 or the following value:
DB_STAT_CLEAR
Reset statistics after returning their values.
The DbEnv::txn_stat()
method may fail and throw a DbException
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors: