<!--$Id: lock_get.so,v 10.28 2000/04/24 16:33:54 bostic Exp $--> <!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <html> <head> <title>Berkeley DB: DbEnv::lock_get</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"> </head> <body bgcolor=white> <a name="2"><!--meow--></a> <table><tr valign=top> <td> <h1>DbEnv::lock_get</h1> </td> <td width="1%"> <a href="../api_cxx/cxx_index.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> <h3><pre> #include <db_cxx.h> <p> int DbEnv::lock_get(u_int32_t locker, u_int32_t flags, const Dbt *obj, const db_lockmode_t lock_mode, DbLock *lock); </pre></h3> <h1>Description</h1> <p>The DbEnv::lock_get method acquires a lock from the lock table, returning information about it in the <b>lock</b> argument. <p>The <b>locker</b> argument specified to DbEnv::lock_get is an unsigned 32-bit integer quantity. It represents the entity requesting or releasing the lock. <p>The <b>flags</b> value must be set to 0 or the following value: <p><dl compact> <p><dt><a name="DB_LOCK_NOWAIT">DB_LOCK_NOWAIT</a><dd>If a lock cannot be granted because the requested lock conflicts with an existing lock, return immediately instead of waiting for the lock to become available. </dl> <p>The <b>obj</b> argument is an untyped byte string that specifies the object to be locked or released. <p>The <b>mode</b> argument is an index into the environment's lock conflict array. See <a href="../api_cxx/env_set_lk_conflicts.html">DbEnv::set_lk_conflicts</a> and <a href="../ref/lock/stdmode.html">Standard Lock Modes</a> for a description of that array. <p>The DbEnv::lock_get method may return or throw an exception encapsulating one of the following values: <p><dl compact> <p><dt><a name="DB_LOCK_NOTGRANTED">DB_LOCK_NOTGRANTED</a><dd>A lock was requested that could not be immediately granted and the <b>flags</b> parameter was set to DB_LOCK_NOWAIT. </dl> <p>Otherwise, the DbEnv::lock_get 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. <h1>Errors</h1> <p>The DbEnv::lock_get method may fail and throw an exception or return a non-zero error for the following conditions: <p><dl compact> <p><dt>DB_LOCK_DEADLOCK<dd>The operation was selected to resolve a deadlock. </dl> <p><dl compact> <p><dt>EINVAL<dd>An invalid flag value or parameter was specified. </dl> <p><dl compact> <p><dt>ENOMEM<dd>The maximum number of locks has been reached. </dl> <p>The DbEnv::lock_get method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::lock_get method may fail and either return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a> or throw an exception encapsulating <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>, in which case all subsequent Berkeley DB calls will fail in the same way. <h3>Classes</h3> <a href="../api_cxx/dbenv_class.html">DbEnv</a>, <a href="../api_cxx/lock_class.html">DbLock</a> <h1>See Also</h1> <a href="../api_cxx/env_set_lk_conflicts.html">DbEnv::set_lk_conflicts</a>, <a href="../api_cxx/env_set_lk_detect.html">DbEnv::set_lk_detect</a>, <a href="../api_cxx/env_set_lk_max_locks.html">DbEnv::set_lk_max_locks</a>, <a href="../api_cxx/env_set_lk_max_lockers.html">DbEnv::set_lk_max_lockers</a>, <a href="../api_cxx/env_set_lk_max_objects.html">DbEnv::set_lk_max_objects</a>, <a href="../api_cxx/env_set_lk_max.html">DbEnv::set_lk_max</a>, <a href="../api_cxx/lock_detect.html">DbEnv::lock_detect</a>, <a href="../api_cxx/lock_get.html">DbEnv::lock_get</a>, <a href="../api_cxx/lock_id.html">DbEnv::lock_id</a>, <a href="../api_cxx/lock_put.html">DbLock::put</a>, <a href="../api_cxx/lock_stat.html">DbEnv::lock_stat</a> and <a href="../api_cxx/lock_vec.html">DbEnv::lock_vec</a>. </tt> <table><tr><td><br></td><td width="1%"> <a href="../api_cxx/cxx_index.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><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> </body> </html>