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<th colspan="3" align="center">DbEnv::rep_set_clockskew()</th>
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<h2 class="title" style="clear: both"><a id="repclockskew"></a>DbEnv::rep_set_clockskew()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::rep_set_clockskew(u_int32_t fast_clock, u_int32_t slow_clock); </pre>
<p>
The <code class="methodname">DbEnv::rep_set_clockskew()</code> method sets the
clock skew ratio among replication group members based on the fastest
and slowest measurements among the group for use with master leases.
Calling this method is optional; the default values for clock skew
assume no skew. The user must also configure leases via the
<a class="xref" href="repconfig.html" title="DbEnv::rep_set_config()">DbEnv::rep_set_config()</a>
method. Additionally, the user must also set the master lease timeout
via the
<a class="xref" href="repset_timeout.html" title="DbEnv::rep_set_timeout()">DbEnv::rep_set_timeout()</a>
method. For Base API applications, the user must also set the number of
sites in the replication group via the
<a class="xref" href="repnsites.html" title="DbEnv::rep_set_nsites()">DbEnv::rep_set_nsites()</a>
method. These methods may be called in any order. For a description
of the clock skew values, see
<a href="../../programmer_reference/rep_clock_skew.html" class="olink">Clock skew</a>
in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>. For a description of
master leases, see
<a href="../../programmer_reference/rep_lease.html" class="olink">Master leases</a> in the
<em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
These arguments can be used to express either raw measurements of a
clock timing experiment or a percentage across machines. For example, if
a group of sites has a 2% variance, then <span class="bold"><strong>fast_clock</strong></span> should be set to 102, and
<span class="bold"><strong>slow_clock</strong></span> should be set to 100. Or,
for a 0.03% difference, you can use 10003 and 10000 respectively.
</p>
<p>
The database environment's replication subsystem may also be
configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax of
the entry in that file is a single line with the string
"rep_set_clockskew", one or more whitespace characters, and the
clockskew specified in two parts: the fast_clock and the
slow_clock. For example, "rep_set_clockskew 102 100". Because the
<a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read when the database environment is opened,
it will silently overrule configuration done before that time.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_clockskew()</code> method configures a database
environment, not only operations performed using the specified
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_clockskew()</code> method may not be called after the
<a class="xref" href="repmgrstart.html" title="DbEnv::repmgr_start()">DbEnv::repmgr_start()</a> or
<a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a>
methods are called.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_clockskew()</code> <span>
<span>
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.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9563696"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9563216"></a>fast_clock</h4>
</div>
</div>
</div>
<p>
The value, relative to the <span class="bold"><strong>slow_clock</strong></span>,
of the fastest clock in the group of sites.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9557520"></a>slow_clock</h4>
</div>
</div>
</div>
<p>
The value of the slowest clock in the group of sites.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9528032"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::rep_set_clockskew()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9576208"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the method was called after replication is started with a
call to the
<a class="xref" href="repmgrstart.html" title="DbEnv::repmgr_start()">DbEnv::repmgr_start()</a> or the
<a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a> method; or if
an invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9574152"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9563912"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
</p>
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