1<!--$Id: set_func_ioinfo.so,v 10.17 2004/08/13 03:39:02 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_func_ioinfo</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_func_ioinfo</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 &lt;db.h&gt;
23<p>
24int
25db_env_set_func_ioinfo(int (*func_ioinfo)(const char *path,
26    int fd, u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep));
27</pre></b>
28<hr size=1 noshade>
29<b>Description: db_env_set_func_ioinfo</b>
30<p>The Berkeley DB library requires the ability to determine the size and I/O
31characteristics of a file.</p>
32<p>The db_env_set_func_ioinfo method configures all operations performed by a process and
33all of its threads of control, not operations confined to a single
34database environment.</p>
35<p>Although the db_env_set_func_ioinfo method may be called at any time during the life of
36the application, it should normally be called before making calls to the
37<a href="../api_c/env_class.html">db_env_create</a> or <a href="../api_c/db_class.html">db_create</a> methods.</p>
38<p>The db_env_set_func_ioinfo method
39returns a non-zero error value on failure
40and 0 on success.
41</p>
42<b>Parameters</b> <br>
43 <b>func_ioinfo</b><ul compact><li>The <b>func_ioinfo</b> parameter is the function which returns the size
44and I/O characteristics of a file.
45<p>The <b>path</b> parameter is the pathname of the file to be checked, and the
46<b>fd</b> parameter is an open file descriptor on the file.</p>
47<p>If the <b>mbytesp</b> and <b>bytesp</b> parameters are non-NULL, the
48<b>ioinfo</b> function must return in them the size of the file: the
49number of megabytes in the file into the memory location to which the
50<b>mbytesp</b> parameter refers, and the number of bytes over and above
51that number of megabytes into the memory location to which the
52<b>bytesp</b> parameter refers.</p>
53<p>In addition, if the <b>iosizep</b> parameter is non-NULL, the <b>ioinfo</b>
54function must return the optimum granularity for I/O operations to the file
55into the memory location to which it refers.</p>
56<p>The <b>func_ioinfo</b> function must return the value of <b>errno</b> on
57failure and 0 on success.</p></ul>
58<br>
59<br><b>See Also</b>
60<a href="../ref/program/runtime.html">Run-time configuration</a>
61</tt>
62<table width="100%"><tr><td><br></td><td align=right>
63<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>
64</td></tr></table>
65<p><font size=1>Copyright (c) 1996,2008 Oracle.  All rights reserved.</font>
66</body>
67</html>
68