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<h2 class="title" style="clear: both"><a id="txnstat"></a>DB_ENV->txn_stat()</h2>
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<pre class="programlisting">#include <db.h>
int
DB_ENV->txn_stat(DB_ENV *env, DB_TXN_STAT **statp, u_int32_t flags); </pre>
<p>
The <code class="methodname">DB_ENV->txn_stat()</code> method returns the transaction subsystem
statistics.
</p>
<p>
The <code class="methodname">DB_ENV->txn_stat()</code> method creates a statistical structure of type
<code class="literal">DB_TXN_STAT</code> 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 class="xref" href="envset_alloc.html" title="DB_ENV->set_alloc()">DB_ENV->set_alloc()</a>
for more information), they are used to allocate the memory;
otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(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>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="bold"><strong>DB_LSN st_last_ckp;</strong></span>
</p>
<p>
The LSN of the last checkpoint.
</p>
</li>
<li>
<p>
<span class="bold"><strong>time_t st_time_ckp;</strong></span>
</p>
<p>
The time the last completed checkpoint finished (as the number of
seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX)
<span class="bold"><strong>time</strong></span> function).
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_last_txnid;</strong></span>
</p>
<p>
The last transaction ID allocated.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxtxns;</strong></span>
</p>
<p>
The maximum number of active transactions configured.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nactive;</strong></span>
</p>
<p>
The number of transactions that are currently active.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nsnapshot;</strong></span>
</p>
<p>
The number of transactions on the snapshot list. These are
transactions which modified a database opened with
<a class="link" href="dbopen.html#dbopen_DB_MULTIVERSION">DB_MULTIVERSION</a>,
and which have committed or aborted, but the copies of pages they
created are still in the cache.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxnactive;</strong></span>
</p>
<p>
The maximum number of active transactions at any one time.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_maxnsnapshot;</strong></span>
</p>
<p>
The maximum number of transactions on the snapshot list at any one
time.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_nbegins;</strong></span>
</p>
<p>
The number of transactions that have begun.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_naborts;</strong></span>
</p>
<p>
The number of transactions that have aborted.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_ncommits;</strong></span>
</p>
<p>
The number of transactions that have committed.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t st_nrestores;</strong></span>
</p>
<p>
The number of transactions that have been restored.
</p>
</li>
<li>
<p>
<span class="bold"><strong>roff_t st_regsize;</strong></span>
</p>
<p>
The size of the transaction region, in bytes.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_region_wait;</strong></span>
</p>
<p>
The number of times that a thread of control was forced to wait before
obtaining the transaction region mutex.
</p>
</li>
<li>
<p>
<span class="bold"><strong>uintmax_t st_region_nowait;</strong></span>
</p>
<p>
The number of times that a thread of control was able to obtain the
transaction region mutex without waiting.
</p>
</li>
<li>
<p>
<span class="bold"><strong>DB_TXN_ACTIVE *st_txnarray;</strong></span>
</p>
<p>
A pointer to an array of <span class="bold"><strong>st_nactive</strong></span>
DB_TXN_ACTIVE structures, describing the currently active
transactions. The following fields of the DB_TXN_ACTIVE structure will
be filled in:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p>
<span class="bold"><strong>u_int32_t txnid;</strong></span>
</p>
<p>
The transaction ID of the transaction.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t parentid;</strong></span>
</p>
<p>
The transaction ID of the parent transaction (or 0, if no parent).
</p>
</li>
<li>
<p>
<span class="bold"><strong>pid_t pid;</strong></span>
</p>
<p>
The process ID of the originator of the transaction.
</p>
</li>
<li>
<p>
<span class="bold"><strong>db_threadid_t tid;</strong></span>
</p>
<p>
The thread of control ID of the originator of the transaction.
</p>
</li>
<li>
<p>
<span class="bold"><strong>DB_LSN lsn;</strong></span>
</p>
<p>
The current log sequence number when the transaction was begun.
</p>
</li>
<li>
<p>
<span class="bold"><strong>DB_LSN read_lsn;</strong></span>
</p>
<p>
The log sequence number of reads for snapshot transactions.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t mvcc_ref;</strong></span>
</p>
<p>
The number of buffer copies created by this transaction that remain
in cache.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int32_t status;</strong></span>
</p>
<p>
One of the following list of constants: TXN_ABORTED, TXN_COMMITTED,
TXN_PREPARED, TXN_RUNNING.
</p>
</li>
<li>
<p>
<span class="bold"><strong>u_int8_t gid[DB_GID_SIZE];</strong></span>
</p>
<p>
If the transaction was prepared using
<a class="xref" href="txnprepare.html" title="DB_TXN->prepare()">DB_TXN->prepare()</a>, then
<span class="bold"><strong>gid</strong></span> contains the
transaction's Global ID. Otherwise,
<span class="bold"><strong>gid's</strong></span> contents are undefined.
</p>
</li>
<li>
<p>
<span class="bold"><strong>char name[];</strong></span>
</p>
<p>
If a name was specified for the transaction, up to the first 50 bytes
of that name, followed by a nul termination byte.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
The <code class="methodname">DB_ENV->txn_stat()</code> method may not be called before the
<a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method is called.
</p>
<p>
The <code class="methodname">DB_ENV->txn_stat()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1710556"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1710952"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or the following value:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">DB_STAT_CLEAR</code>
</p>
<p>
Reset statistics after returning their values.
</p>
</li>
</ul>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1711273"></a>statp</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>statp</strong></span> parameter references memory
into which a pointer to the allocated statistics structure is copied.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1711013"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DB_ENV->txn_stat()</code> <span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1710958"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
An invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1711099"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>, <a class="link" href="txn.html" title="Chapter 12. The DB_TXN Handle">DB_TXN</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1710965"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a>
</p>
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