1<!--$Id: env_set_lk_detect.so,v 10.50 2006/02/27 14:51:30 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DB_ENV->set_lk_detect</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DB_ENV->set_lk_detect</b> 14</td> 15<td align=right> 16<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25DB_ENV->set_lk_detect(DB_ENV *dbenv, u_int32_t detect); 26<p> 27int 28DB_ENV->get_lk_detect(DB_ENV *dbenv, u_int32_t *lk_detectp); 29</pre></b> 30<hr size=1 noshade> 31<b>Description: DB_ENV->set_lk_detect</b> 32<p>Set if the deadlock detector is to be run whenever a lock conflict 33occurs, and specify what lock request(s) should be rejected. As 34transactions acquire locks on behalf of a single locker ID, rejecting a 35lock request associated with a transaction normally requires the 36transaction be aborted.</p> 37<p>The database environment's deadlock detector configuration may also be configured using the 38environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file. The syntax of the entry in that 39file is a single line with the string "set_lk_detect", one or more whitespace 40characters, and the method <b>detect</b> parameter as a string; for example, 41"set_lk_detect DB_LOCK_OLDEST". 42Because the <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment 43is opened, it will silently overrule configuration done before that 44time.</p> 45<p>The DB_ENV->set_lk_detect method configures a database environment, not only operations 46performed using the specified <a href="../api_c/env_class.html">DB_ENV</a> handle.</p> 47<p>The DB_ENV->set_lk_detect method may be called at any time during the life of the 48application.</p> 49<p>The DB_ENV->set_lk_detect method 50returns a non-zero error value on failure 51and 0 on success. 52</p> 53<b>Parameters</b> <br> 54 <b>detect</b><ul compact><li>The <b>detect</b> parameter configures the deadlock detector. The 55specified value must be one of the following list: 56<br> 57<b><a name="DB_LOCK_DEFAULT">DB_LOCK_DEFAULT</a></b><ul compact><li>Use whatever lock policy was specified when the database environment 58was created. If no lock policy has yet been specified, set the lock 59policy to DB_LOCK_RANDOM.</ul> 60<b><a name="DB_LOCK_EXPIRE">DB_LOCK_EXPIRE</a></b><ul compact><li>Reject lock requests which have timed out. No other deadlock detection 61is performed.</ul> 62<b><a name="DB_LOCK_MAXLOCKS">DB_LOCK_MAXLOCKS</a></b><ul compact><li>Reject the lock request for the locker ID with the most locks.</ul> 63<b><a name="DB_LOCK_MAXWRITE">DB_LOCK_MAXWRITE</a></b><ul compact><li>Reject the lock request for the locker ID with the most write locks.</ul> 64<b><a name="DB_LOCK_MINLOCKS">DB_LOCK_MINLOCKS</a></b><ul compact><li>Reject the lock request for the locker ID with the fewest locks.</ul> 65<b><a name="DB_LOCK_MINWRITE">DB_LOCK_MINWRITE</a></b><ul compact><li>Reject the lock request for the locker ID with the fewest write locks.</ul> 66<b><a name="DB_LOCK_OLDEST">DB_LOCK_OLDEST</a></b><ul compact><li>Reject the lock request for the locker ID with the oldest lock.</ul> 67<b><a name="DB_LOCK_RANDOM">DB_LOCK_RANDOM</a></b><ul compact><li>Reject the lock request for a random locker ID.</ul> 68<b><a name="DB_LOCK_YOUNGEST">DB_LOCK_YOUNGEST</a></b><ul compact><li>Reject the lock request for the locker ID with the youngest lock.</ul> 69<br></ul> 70<br> 71<br><b>Errors</b> 72<p>The DB_ENV->set_lk_detect method 73may fail and return one of the following non-zero errors:</p> 74<br> 75<b>EINVAL</b><ul compact><li>An 76invalid flag value or parameter was specified.</ul> 77<br> 78<hr size=1 noshade> 79<b>Description: DB_ENV->get_lk_detect</b> 80<p>The DB_ENV->get_lk_detect method returns the deadlock detector configuration.</p> 81<p>The DB_ENV->get_lk_detect method may be called at any time during the life of the 82application.</p> 83<p>The DB_ENV->get_lk_detect method 84returns a non-zero error value on failure 85and 0 on success. 86</p> 87<b>Parameters</b> <br> 88 <b>lk_detectp</b><ul compact><li>The DB_ENV->get_lk_detect method returns the 89deadlock detector configuration in <b>lk_detectp</b>.</ul> 90<br> 91<hr size=1 noshade> 92<br><b>Class</b> 93<a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/lock_class.html">DB_LOCK</a> 94<br><b>See Also</b> 95<a href="../api_c/lock_list.html">Locking Subsystem and Related Methods</a> 96</tt> 97<table width="100%"><tr><td><br></td><td align=right> 98<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> 99</td></tr></table> 100<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 101</body> 102</html> 103
