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<h2 class="title" style="clear: both"><a id="dbset_feedback"></a>Db::set_feedback()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
Db::set_feedback(void (*db_feedback_fcn)(DB *dbp, int opcode, int percent));</pre>
<p>
Some operations performed by the Berkeley DB library can take non-trivial amounts of time.
The <code class="methodname">Db::set_feedback()</code> method can be used by applications to
monitor progress within these operations. When an operation is likely to take a long time,
Berkeley DB will call the specified callback function with progress information.
</p>
<p>
It is up to the callback function to display this information in an
appropriate manner.
</p>
<p>
The <code class="methodname">Db::set_feedback()</code> method may be called at any time during the
life of the application.
</p>
<p>
The <code class="methodname">Db::set_feedback()</code> method returns a non-zero error value on
failure and 0 on success.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Berkeley DB is not re-entrant. Callback functions should not attempt to make
library calls (for example, to release locks or close open handles). Re-entering
Berkeley DB is not guaranteed to work correctly, and the results are undefined.
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<h3 class="title"><a id="id1646919"></a>Parameters</h3>
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<h4 class="title"><a id="id1646933"></a>db_feedback_fcn</h4>
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<p>
The <span class="bold"><strong>db_feedback_fcn</strong></span> parameter is the
application-specified feedback function called to report Berkeley DB
operation progress. The callback function must take three parameters:
</p>
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<li>
<p>
<code class="literal">dbp</code>
</p>
<p>
The <span class="bold"><strong>dbp</strong></span> parameter is a reference to
the enclosing database.
</p>
</li>
<li>
<p>
<code class="literal">opcode</code>
</p>
<p>
The <span class="bold"><strong>opcode</strong></span> parameter is an operation
code. The <span class="bold"><strong>opcode</strong></span> parameter may take
on any of the following values:
</p>
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<li>
<p><a id="set_feedback_DB_UPGRADE"></a>
<code class="literal">DB_UPGRADE</code>
</p>
<p>
The underlying database is being upgraded.
</p>
</li>
<li>
<p><a id="set_feedback_DB_VERIFY"></a>
<code class="literal">DB_VERIFY</code>
</p>
<p>
The underlying database is being verified.
</p>
</li>
</ul>
</div>
</li>
<li>
<p>
<code class="literal">percent</code>
</p>
<p>
The <span class="bold"><strong>percent</strong></span> parameter is the percent
of the operation that has been completed, specified as an integer
value between 0 and 100.
</p>
</li>
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<h3 class="title"><a id="id1646920"></a>Class</h3>
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<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a>
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<h3 class="title"><a id="id1647077"></a>See Also</h3>
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<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
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