<!--$Id: txn_stat.so,v 10.68 2007/09/21 20:06:04 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DB_ENV->txn_stat</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <b>DB_ENV->txn_stat</b> </td> <td align=right> <a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> <a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <b><pre> #include <db.h> <p> int DB_ENV->txn_stat(DB_ENV *env, DB_TXN_STAT **statp, u_int32_t flags); <p> int DB_ENV->txn_stat_print(DB_ENV *env, u_int32_t flags); </pre></b> <hr size=1 noshade> <b>Description: DB_ENV->txn_stat</b> <p>The DB_ENV->txn_stat method returns the transaction subsystem statistics.</p> <p>The DB_ENV->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_c/env_set_alloc.html">DB_ENV->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> <br> <b>DbLsn st_last_ckp;</b><ul compact><li>The LSN of the last checkpoint.</ul> <b>time_t st_time_ckp;</b><ul compact><li>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).</ul> <b>u_int32_t st_last_txnid;</b><ul compact><li>The last transaction ID allocated.</ul> <b>u_int32_t st_maxtxns;</b><ul compact><li>The maximum number of active transactions configured.</ul> <b>u_int32_t st_nactive;</b><ul compact><li>The number of transactions that are currently active.</ul> <b>u_int32_t st_nsnapshot;</b><ul compact><li>The number of transactions on the snapshot list. These are transactions which modified a database opened with <a href="../api_c/db_open.html#DB_MULTIVERSION">DB_MULTIVERSION</a>, and which have committed or aborted, but the copies of pages they created are still in the cache.</ul> <b>u_int32_t st_maxnactive;</b><ul compact><li>The maximum number of active transactions at any one time.</ul> <b>u_int32_t st_maxnsnapshot;</b><ul compact><li>The maximum number of transactions on the snapshot list at any one time.</ul> <b>u_int32_t st_nbegins;</b><ul compact><li>The number of transactions that have begun.</ul> <b>u_int32_t st_naborts;</b><ul compact><li>The number of transactions that have aborted.</ul> <b>u_int32_t st_ncommits;</b><ul compact><li>The number of transactions that have committed.</ul> <b>u_int32_t st_nrestores;</b><ul compact><li>The number of transactions that have been restored.</ul> <b>roff_t st_regsize;</b><ul compact><li>The size of the transaction region, in bytes.</ul> <b>u_int32_t st_region_wait;</b><ul compact><li>The number of times that a thread of control was forced to wait before obtaining the transaction region mutex.</ul> <b>u_int32_t st_region_nowait;</b><ul compact><li>The number of times that a thread of control was able to obtain the transaction region mutex without waiting.</ul> <b>DB_TXN_ACTIVE *st_txnarray;</b><ul compact><li>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:</ul> <br> <b>u_int32_t txnid;</b><ul compact><li>The transaction ID of the transaction.</ul> <b>u_int32_t parentid;</b><ul compact><li>The transaction ID of the parent transaction (or 0, if no parent).</ul> <b>pid_t pid;</b><ul compact><li>The process ID of the originator of the transaction.</ul> <b>uintmax_t tid;</b><ul compact><li>The thread of control ID of the originator of the transaction.</ul> <b>DbLsn lsn;</b><ul compact><li>The current log sequence number when the transaction was begun.</ul> <b>DbLsn read_lsn;</b><ul compact><li>The log sequence number of reads for snapshot transactions.</ul> <b>u_int32_t mvcc_ref;</b><ul compact><li>The number of buffer copies created by this transaction that remain in cache.</ul> <b>u_int32_t status;</b><ul compact><li>One of the following list of constants: TXN_ABORTED, TXN_COMMITTED, TXN_PREPARED, TXN_RUNNING.</ul> <b>u_int32_t xa_status;</b><ul compact><li>If the transaction is an XA transaction, the <b>xa_status</b> of the transaction will be one of the following list of constants: TXN_XA_ABORTED, TXN_XA_DEADLOCKED, TXN_XA_ENDED, TXN_XA_PREPARED, TXN_XA_STARTED, or TXN_XA_SUSPENDED. Otherwise, the <b>xa_status</b> will be 0.</ul> <b>u_int8_t xid[DB_XIDDATASIZE];</b><ul compact><li>If the transaction is an XA transaction, the transaction's XA ID. If the transaction was prepared separately from the XA interfaces, the transaction's Global ID. Otherwise, the <b>xid</b> contents are undefined.</ul> <b>char name[];</b><ul compact><li>If a name was specified for the transaction, up to the first 50 bytes of that name, followed by a nul termination byte.</ul> <br> <br> <p>The DB_ENV->txn_stat method may not be called before the <a href="../api_c/env_open.html">DB_ENV->open</a> method is called.</p> <p>The DB_ENV->txn_stat method returns a non-zero error value on failure and 0 on success. </p> <b>Parameters</b> <br> <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or the following value: <br> <b><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a></b><ul compact><li>Reset statistics after returning their values.</ul> <br></ul> <b>statp</b><ul compact><li>The <b>statp</b> parameter references memory into which a pointer to the allocated statistics structure is copied.</ul> <br> <br><b>Errors</b> <p>The DB_ENV->txn_stat method may fail and return one of the following non-zero errors:</p> <br> <b>EINVAL</b><ul compact><li>An invalid flag value or parameter was specified.</ul> <br> <hr size=1 noshade> <b>Description: DB_ENV->txn_stat_print</b> <p>The DB_ENV->txn_stat_print method displays the transaction subsystem statistical information, as described for the DB_ENV->txn_stat method. The information is printed to a specified output channel (see the <a href="../api_c/env_set_msgfile.html">DB_ENV->set_msgfile</a> method for more information), or passed to an application callback function (see the <a href="../api_c/env_set_msgcall.html">DB_ENV->set_msgcall</a> method for more information).</p> <p>The DB_ENV->txn_stat_print method may not be called before the <a href="../api_c/env_open.html">DB_ENV->open</a> method is called.</p> <p>The DB_ENV->txn_stat_print method returns a non-zero error value on failure and 0 on success. </p> <b>Parameters</b> <br> <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one or more of the following values: <br> <b><a name="DB_STAT_ALL">DB_STAT_ALL</a></b><ul compact><li>Display all available information.</ul> <b><a name="DB_STAT_CLEAR">DB_STAT_CLEAR</a></b><ul compact><li>Reset statistics after displaying their values.</ul> <br></ul> <br> <hr size=1 noshade> <br><b>Class</b> <a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/txn_class.html">DB_TXN</a> <br><b>See Also</b> <a href="../api_c/txn_list.html">Transaction Subsystem and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>