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authorLaurent Bercot <ska-skaware@skarnet.org>2015-01-15 20:14:44 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2015-01-15 20:14:44 +0000
commit87c5b2118efcee65eeda3f743d081ea9c2b866d9 (patch)
tree31ca07d6134adf44bc3d58f4fcf4ea8be9cb7dbb /doc/libs6/s6lockd-helper.html
parentcd2500fcc704287c4994a3253b593593c867913e (diff)
downloads6-87c5b2118efcee65eeda3f743d081ea9c2b866d9.tar.xz
Move Unix domain utilities and access control utilites,
as well as the accessrules library, from s6-networking to here
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+<html>
+ <head>
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+ <meta http-equiv="Content-Language" content="en" />
+ <title>s6: the s6lockd-helper internal program</title>
+ <meta name="Description" content="s6: the s6lockd-helper internal program" />
+ <meta name="Keywords" content="s6 s6lockd-helper lockd asynchronous timed lock daemon helper" />
+ <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> -->
+ </head>
+<body>
+
+<a href="index.html">libs6</a><br />
+<a href="../">s6</a><br />
+<a href="http://skarnet.org/software/">Software</a><br />
+<a href="http://skarnet.org/">skarnet.org</a><p />
+
+<h1> The <tt>s6lockd-helper</tt> program </h1>
+
+<p>
+<tt>s6lockd-helper</tt> is a helper program for the s6lock daemon.
+It just acquires a lock and holds it until it is killed or told to
+exit by its parent daemon.
+</p>
+
+<h2> Interface </h2>
+
+<p>
+ s6lockd-helper is not meant to be invoked directly by the user:
+it will be spawned by the
+<a href="s6lockd.html">s6lockd</a> program.
+</p>
+
+<h2> Notes </h2>
+
+<ul>
+ <li> s6lockd-helper blocks on lock acquisition until it succeeds. It then
+notifies its parent. It exits when its parent tells him to (i.e. when the
+client asks for lock release). During the lock acquisition phase, it can
+be killed if its parent detects a timeout. </li>
+ <li> One s6lockd-helper process per lock is the only way (apart from
+threads) to implement timed lock acquisition. This can lead to a lot of
+s6lockd-helper processes, but this is not a problem:
+ <ul>
+ <li> Processes are not a scarce resource. Today's schedulers work in O(1),
+i.e. a sleeping process takes no scheduling time at all. </li>
+ <li> s6lockd-helper is extremely tiny. Every instance should use up at
+most one or two pages of non-sharable memory. </li>
+ </ul> </li>
+</ul>
+
+</body>
+</html>