<!--$Id: set_func_yield.so,v 10.8 2000/05/31 15:10:01 bostic Exp $--> <!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <html> <head> <title>Berkeley DB: db_env_set_func_yield</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>db_env_set_func_yield</h1> </td> <td width="1%"> <a href="../api_c/c_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.h> <p> int db_env_set_func_yield(int (*func_yield)(void)); </pre></h3> <h1>Description</h1> <p>The Berkeley DB library requires the ability to yield the processor from the current thread of control to any other waiting threads of control. The <b>func_yield</b> argument must conform to the following interface: <p><blockquote><pre>int yield(void);</pre></blockquote> <p>The <b>func_yield</b> function must be able to cause the rescheduling all participants in the current Berkeley DB environment, whether threaded or not. It may be incorrect to supply a thread <b>yield</b> function if more than a single process is operating in the Berkeley DB environment. This is because many thread-yield functions will not allow other processes to run, and the contested lock may be held by another process, not by another thread. <p>If no <b>func_yield</b> function is specified, or if the <b>yield</b> function returns an error, the function specified by the <a href="../api_c/set_func_sleep.html">db_env_set_func_sleep</a> entry will be used instead or subsequently, i.e., if no <b>yield</b> function is specified, or it is possible for the <b>yield</b> function to fail, the <b>sleep</b> function <b>must</b> cause the processor to reschedule any waiting threads of control for execution. <p>The <b>func_yield</b> function must return the value of <b>errno</b> on failure and 0 on success. <p>The db_env_set_func_yield interface affects the entire application, not a single database or database environment. <p>While the db_env_set_func_yield interface may be used to configure Berkeley DB at any time during the life of the application, it should normally be called before making any calls to the <a href="../api_c/env_create.html">db_env_create</a> or <a href="../api_c/db_create.html">db_create</a> functions. <p>The db_env_set_func_yield function returns a non-zero error value on failure and 0 on success. <h1>Errors</h1> <p><dl compact> <p><dt>EINVAL<dd>An invalid flag value or parameter was specified. </dl> <h1>See Also</h1> <a href="../api_c/set_func_close.html">db_env_set_func_close</a>, <a href="../api_c/set_func_dirfree.html">db_env_set_func_dirfree</a>, <a href="../api_c/set_func_dirlist.html">db_env_set_func_dirlist</a>, <a href="../api_c/set_func_exists.html">db_env_set_func_exists</a>, <a href="../api_c/set_func_free.html">db_env_set_func_free</a>, <a href="../api_c/set_func_fsync.html">db_env_set_func_fsync</a>, <a href="../api_c/set_func_ioinfo.html">db_env_set_func_ioinfo</a>, <a href="../api_c/set_func_malloc.html">db_env_set_func_malloc</a>, <a href="../api_c/set_func_map.html">db_env_set_func_map</a>, <a href="../api_c/set_func_open.html">db_env_set_func_open</a>, <a href="../api_c/set_func_read.html">db_env_set_func_read</a>, <a href="../api_c/set_func_realloc.html">db_env_set_func_realloc</a>, <a href="../api_c/set_func_seek.html">db_env_set_func_seek</a>, <a href="../api_c/set_func_sleep.html">db_env_set_func_sleep</a>, <a href="../api_c/set_func_unlink.html">db_env_set_func_unlink</a>, <a href="../api_c/set_func_unmap.html">db_env_set_func_unmap</a>, <a href="../api_c/set_func_write.html">db_env_set_func_write</a> and <a href="../api_c/set_func_yield.html">db_env_set_func_yield</a>. </tt> <table><tr><td><br></td><td width="1%"> <a href="../api_c/c_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>