2011-09-13 17:44:24 +00:00
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
< html xmlns = "http://www.w3.org/1999/xhtml" >
< head >
< meta http-equiv = "Content-Type" content = "text/html; charset=UTF-8" / >
< title > DB_ENV-> rep_set_clockskew()< / title >
< link rel = "stylesheet" href = "apiReference.css" type = "text/css" / >
< meta name = "generator" content = "DocBook XSL Stylesheets V1.73.2" / >
< link rel = "start" href = "index.html" title = "Berkeley DB C API Reference" / >
< link rel = "up" href = "rep.html" title = "Chapter / >
< link rel = "prev" href = "repmessage.html" title = "DB_ENV->rep_process_message()" / >
< link rel = "next" href = "repconfig.html" title = "DB_ENV->rep_set_config()" / >
< / head >
< body >
< div xmlns = "" class = "navheader" >
< div class = "libver" >
< p > Library Version 11.2.5.2< / p >
< / div >
< table width = "100%" summary = "Navigation header" >
< tr >
< th colspan = "3" align = "center" > DB_ENV-> rep_set_clockskew()< / th >
< / tr >
< tr >
< td width = "20%" align = "left" > < a accesskey = "p" href = "repmessage.html" > Prev< / a > < / td >
< th width = "60%" align = "center" > Chapter
Replication Methods
< / th >
< td width = "20%" align = "right" > < a accesskey = "n" href = "repconfig.html" > Next< / a > < / td >
< / tr >
< / table >
< hr / >
< / div >
< div class = "sect1" lang = "en" xml:lang = "en" >
< div class = "titlepage" >
< div >
< div >
< h2 class = "title" style = "clear: both" > < a id = "repclockskew" > < / a > DB_ENV-> rep_set_clockskew()< / h2 >
< / div >
< / div >
< / div >
< pre class = "programlisting" > #include < db.h>
int
DB_ENV-> rep_set_clockskew(DB_ENV *env,
u_int32_t fast_clock, u_int32_t slow_clock); < / pre >
< p >
The < code class = "methodname" > DB_ENV-> 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 = "DB_ENV->rep_set_config()" > DB_ENV-> 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 = "DB_ENV->rep_set_timeout()" > DB_ENV-> 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 = "DB_ENV->rep_set_nsites()" > DB_ENV-> 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" > DB_ENV-> rep_set_clockskew()< / code > method configures a database
environment, not only operations performed using the specified
< a class = "link" href = "env.html" title = "Chapter > DB_ENV< / a > handle.
< / p >
< p >
The < code class = "methodname" > DB_ENV-> rep_set_clockskew()< / code > method may not be called after the
< a class = "xref" href = "repmgrstart.html" title = "DB_ENV->repmgr_start()" > DB_ENV-> repmgr_start()< / a > or
< a class = "xref" href = "repstart.html" title = "DB_ENV->rep_start()" > DB_ENV-> rep_start()< / a >
methods are called.
< / p >
< p >
The < code class = "methodname" > DB_ENV-> rep_set_clockskew()< / code > < span >
< span >
method returns a non-zero error value on failure and 0 on success.
< / span >
< / span >
< / p >
< div class = "sect2" lang = "en" xml:lang = "en" >
< div class = "titlepage" >
< div >
< div >
2011-12-20 00:07:10 +00:00
< h3 class = "title" > < a id = "id3747506" > < / a > Parameters< / h3 >
2011-09-13 17:44:24 +00:00
< / div >
< / div >
< / div >
< div class = "sect3" lang = "en" xml:lang = "en" >
< div class = "titlepage" >
< div >
< div >
2011-12-20 00:07:10 +00:00
< h4 class = "title" > < a id = "id3747651" > < / a > fast_clock< / h4 >
2011-09-13 17:44:24 +00:00
< / 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 >
2011-12-20 00:07:10 +00:00
< h4 class = "title" > < a id = "id3747935" > < / a > slow_clock< / h4 >
2011-09-13 17:44:24 +00:00
< / 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 >
2011-12-20 00:07:10 +00:00
< h3 class = "title" > < a id = "id3747440" > < / a > Errors< / h3 >
2011-09-13 17:44:24 +00:00
< / div >
< / div >
< / div >
< p >
The < code class = "methodname" > DB_ENV-> rep_set_clockskew()< / code > < span >
< span >
method may fail and return one of the following non-zero errors:
< / span >
< / span >
< / p >
< div class = "sect3" lang = "en" xml:lang = "en" >
< div class = "titlepage" >
< div >
< div >
2011-12-20 00:07:10 +00:00
< h4 class = "title" > < a id = "id3748271" > < / a > EINVAL< / h4 >
2011-09-13 17:44:24 +00:00
< / 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 = "DB_ENV->repmgr_start()" > DB_ENV-> repmgr_start()< / a > or the
< a class = "xref" href = "repstart.html" title = "DB_ENV->rep_start()" > DB_ENV-> 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 >
2011-12-20 00:07:10 +00:00
< h3 class = "title" > < a id = "id3748253" > < / a > Class< / h3 >
2011-09-13 17:44:24 +00:00
< / div >
< / div >
< / div >
< p >
< a class = "link" href = "env.html" title = "Chapter > DB_ENV< / a >
< / p >
< / div >
< div class = "sect2" lang = "en" xml:lang = "en" >
< div class = "titlepage" >
< div >
< div >
2011-12-20 00:07:10 +00:00
< h3 class = "title" > < a id = "id3748307" > < / a > See Also< / h3 >
2011-09-13 17:44:24 +00:00
< / div >
< / div >
< / div >
< p >
< a class = "xref" href = "rep.html#replist" title = "Replication and Related Methods" > Replication and Related Methods< / a >
< / p >
< / div >
< / div >
< div class = "navfooter" >
< hr / >
< table width = "100%" summary = "Navigation footer" >
< tr >
< td width = "40%" align = "left" > < a accesskey = "p" href = "repmessage.html" > Prev< / a > < / td >
< td width = "20%" align = "center" >
< a accesskey = "u" href = "rep.html" > Up< / a >
< / td >
< td width = "40%" align = "right" > < a accesskey = "n" href = "repconfig.html" > Next< / a > < / td >
< / tr >
< tr >
< td width = "40%" align = "left" valign = "top" > DB_ENV-> rep_process_message() < / td >
< td width = "20%" align = "center" >
< a accesskey = "h" href = "index.html" > Home< / a >
< / td >
< td width = "40%" align = "right" valign = "top" > > rep_set_config()< / td >
< / tr >
< / table >
< / div >
< / body >
< / html >
