mariadb/bdb/docs/api_c/set_func_ioinfo.html
tim@threads.polyesthetic.msg 89dad52004 Import changeset
2001-03-04 19:42:05 -05:00

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<h1>db_env_set_func_ioinfo</h1>
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<h3><pre>
#include &lt;db.h&gt;
<p>
int
db_env_set_func_ioinfo(int (*func_ioinfo)(const char *path,
int fd, u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep));
</pre></h3>
<h1>Description</h1>
<p>The Berkeley DB library requires the ability to determine the size and I/O
characteristics of a file. The <b>func_ioinfo</b> argument must conform
to the following interface:
<p><blockquote><pre>int ioinfo(const char *path, int fd,
u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep);</pre></blockquote>
<p>The <b>path</b> argument is the pathname of the file to be checked, and the
<b>fd</b> argument is an open file descriptor on the file.
<p>If the <b>mbytesp</b> and <b>bytesp</b> arguments are non-NULL, the
<b>ioinfo</b> function must return in them the size of the file: the
number of megabytes in the file into the memory location referenced by
the <b>mbytesp</b> argument, and the number of bytes over and above that
number of megabytes into the memory location referenced by the
<b>bytesp</b> argument.
<p>In addition, if the <b>iosizep</b> argument is non-NULL, the <b>ioinfo</b>
function must return the optimum granularity for I/O operations to the file
in the memory location referenced by it.
<p>The <b>func_ioinfo</b> function must return the value of <b>errno</b> on
failure and 0 on success.
<p>The db_env_set_func_ioinfo interface affects the entire application, not a single
database or database environment.
<p>While the db_env_set_func_ioinfo 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_ioinfo 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>
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