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<!--$Id: txn_stat.so,v 10.61 2004/09/28 17:57:03 bostic Exp $-->
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<title>Berkeley DB: DbEnv::txn_stat</title>
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<h3>DbEnv::txn_stat</h3>
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<tt>
<h3><pre>
#include <db_cxx.h>
<p>
int
DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags);
<p>
int
DbEnv::txn_stat_print(u_int32_t flags);
</pre></h3>
<hr size=1 noshade>
<h3>Description: DbEnv::txn_stat</h3>
<p>The DbEnv::txn_stat method returns the transaction subsystem statistics.</p>
<p>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.</p>
<p>Statistical structures are stored in allocated memory. If application-specific allocation
routines have been declared (see <a href="../api_cxx/env_set_alloc.html">DbEnv::set_alloc</a> for more
information), they are used to allocate the memory; otherwise, the
standard C library <b>malloc</b>(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.</p>
<p>The following DB_TXN_STAT fields will be filled in:</p>
<dl compact>
<dt>DbLsn st_last_ckp;<dd>The LSN of the last checkpoint.
<dt>time_t st_time_ckp;<dd>The time the last completed checkpoint finished (as the number of seconds
since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX) <b>time</b> function).
<dt>u_int32_t st_last_txnid;<dd>The last transaction ID allocated.
<dt>u_int32_t st_maxtxns;<dd>The maximum number of active transactions configured.
<dt>u_int32_t st_nactive;<dd>The number of transactions that are currently active.
<dt>u_int32_t st_maxnactive;<dd>The maximum number of active transactions at any one time.
<dt>u_int32_t st_nbegins;<dd>The number of transactions that have begun.
<dt>u_int32_t st_naborts;<dd>The number of transactions that have aborted.
<dt>u_int32_t st_ncommits;<dd>The number of transactions that have committed.
<dt>u_int32_t st_nrestores;<dd>The number of transactions that have been restored.
<dt>roff_t st_regsize;<dd>The size of the region, in bytes.
<dt>u_int32_t st_region_wait;<dd>The number of times that a thread of control was forced to wait before
obtaining the region lock.
<dt>u_int32_t st_region_nowait;<dd>The number of times that a thread of control was able to obtain
the region lock without waiting.
<dt>DB_TXN_ACTIVE *st_txnarray;<dd>A pointer to an array of <b>st_nactive</b> DB_TXN_ACTIVE structures,
describing the currently active transactions. The following fields of
the DB_TXN_ACTIVE structure will be filled in:
<dl compact>
<dt>u_int32_t txnid;<dd>The transaction ID of the transaction.
<dt>u_int32_t parentid;<dd>The transaction ID of the parent transaction (or 0, if no parent).
<dt>DbLsn lsn;<dd>The current log sequence number when the transaction was begun.
<dt>u_int32_t xa_status;<dd>If the transaction is an XA transaction, the status of the transaction,
otherwise 0.
<dt>u_int8_t xid[DB_XIDDATASIZE];<dd>If the transaction is an XA transaction, the transaction's XA ID.
</dl>
</dl>
<p>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.
</p>
<h3>Parameters</h3>
<dl compact>
<dt><b>flags</b><dd>The <b>flags</b> parameter must be set to 0 or
the following value:
<dl compact>
<dt><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a><dd>Reset statistics after returning their values.
</dl>
<dt><b>statp</b><dd>The <b>statp</b> parameter references memory into which
a pointer to the allocated statistics structure is copied.
</dl>
<h3>Errors</h3>
<p>The DbEnv::txn_stat method
may fail and throw
<a href="../api_cxx/except_class.html">DbException</a>,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:</p>
<dl compact>
<dt>EINVAL<dd>An
invalid flag value or parameter was specified.
</dl>
<hr size=1 noshade>
<h3>Description: DbEnv::txn_stat_print</h3>
<p>The DbEnv::txn_stat_print method returns the
transaction subsystem statistical information, as described for the DbEnv::txn_stat method.
The information is printed to a specified output channel (see the
<a href="../api_cxx/env_set_msgfile.html">DbEnv::set_msgfile</a> method for more information), or passed to an
application callback function (see the <a href="../api_cxx/env_set_msgcall.html">DbEnv::set_msgcall</a> method for
more information).</p>
<p>The DbEnv::txn_stat_print method may not be called before the <a href="../api_cxx/env_open.html">DbEnv::open</a> method has
been called.</p>
<p>The DbEnv::txn_stat_print 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.
</p>
<h3>Parameters</h3>
<dl compact>
<dt><b>flags</b><dd>The <b>flags</b> parameter must be set to 0 or
the following value:
<dl compact>
<dt><a name="DB_STAT_ALL">DB_STAT_ALL</a><dd>Display all available information.
</dl>
</dl>
<hr size=1 noshade>
<h3>Class</h3>
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>
<h3>See Also</h3>
<a href="../api_cxx/txn_list.html">Transaction Subsystem and Related Methods</a>
</tt>
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