<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DB_ENV->txn_stat()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> <link rel="up" href="txn.html" title="Chapter 12. The DB_TXN Handle" /> <link rel="prev" href="txnset_timeout.html" title="DB_TXN->set_timeout()" /> <link rel="next" href="txnstat_print.html" title="DB_ENV->txn_stat_print()" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DB_ENV->txn_stat()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="txnset_timeout.html">Prev</a> </td> <th width="60%" align="center">Chapter 12. The DB_TXN Handle </th> <td width="20%" align="right"> <a accesskey="n" href="txnstat_print.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="txnstat"></a>DB_ENV->txn_stat()</h2> </div> </div> </div> <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="id1710809"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1711138"></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="id1711383"></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="id1710824"></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="id1711022"></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="id1711278"></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="id1710839"></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> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="txnset_timeout.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="txn.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="txnstat_print.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DB_TXN->set_timeout() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DB_ENV->txn_stat_print()</td> </tr> </table> </div> </body> </html>