1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_event_wait</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
a.headerlink {
color: #c60f0f;
font-size: 0.8em;
padding: 0 4px 0 4px;
text-decoration: none;
visibility: hidden;
}
a.headerlink:hover {
background-color: #c60f0f;
color: white;
}
h1:hover > a.headerlink, h2:hover > a.headerlink, h3:hover > a.headerlink, dt:hover > a.headerlink {
visibility: visible;
}
</style><a href="index.html">Index </a>·
<a href="systemd.directives.html">Directives </a>·
<a href="../python-systemd/index.html">Python </a>·
<a href="../libudev/index.html">libudev </a>·
<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 220</span><hr><div class="refentry"><a name="sd_event_wait"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_event_wait, sd_event_prepare, sd_event_dispatch — Run parts of libsystemd event loop</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-event.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_event_prepare</b>(</code></td><td>sd_event *<var class="pdparam">event</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_event_wait</b>(</code></td><td>sd_event *<var class="pdparam">event</var>, </td></tr><tr><td> </td><td>uint64_t <var class="pdparam">timeout</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_event_dispatch</b>(</code></td><td>sd_event *<var class="pdparam">event</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm140719517802064"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p>Functions described here form parts of an event loop.</p><p><code class="function">sd_event_prepare</code> checks for pending
events and arms necessary timers. If any events are ready to be
processed, it returns a positive value, and the events should be
processed with <code class="function">sd_event_dispatch</code>.
<code class="function">sd_event_dispatch</code> runs a handler for one of
the events from the sources with the highest priority. On success,
<code class="function">sd_event_dispatch</code> returns either 0, which
means that the loop is finished, or a positive value, which means
that the loop is again in the initial state and
<code class="function">sd_event_prepare</code> should be called again.
</p><p>In case <code class="function">sd_event_prepare</code> returned 0,
<code class="function">sd_event_wait</code> should be called to wait for
events or a timeout. If any events are ready to be processed, it
returns a positive value, and the events should be processed with
<code class="function">sd_event_dispatch</code>. Otherwise, the loop is
back in the initial state and <code class="function">sd_event_prepare</code>
should be called again.</p><pre class="programlisting">
┌──────────┐
│ initial ├──←←←←←←←←←←←←←←←←←←←─┐
└───┬──────┘ ↑
│ ↑
sd_event_prepare ┌─────────┐ ↑
├ 0 →→→→→→→──┤ armed │ ↑
1 └───┬─────┘ ↑
↓ │ ↑
↓ sd_event_wait ↑
├───←←←←←←←─── 1 ┴─ 0 →→→→→→→─┘
┌───┴──────┐ ↑
│ pending │ ↑
└───┬──────┘ ↑
│ ↑
sd_event_dispatch ↑
↓ ↑
├ 1 ──────────→→→→→→→─────────┘
0
↓
┌───┴──────┐
│ finished │
└──────────┘
</pre><p>All three functions as the first argument take the event
loop object <em class="parameter"><code>event</code></em> that is created with with
<code class="function">sd_event_new</code>. The timeout for
<code class="function">sd_event_wait</code> is specified with
<em class="parameter"><code>timeout</code></em> in milliseconds.
<code class="constant">(uint64_t) -1</code> may be used to specify an
infinite timeout.</p></div><div class="refsect1"><a name="idm140719517788240"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these functions return 0 or a positive integer.
On failure, they return a negative errno-style error code. In case
of <code class="function">sd_event_prepare</code> and
<code class="function">sd_event_wait</code> a positive value means that
events are ready to be processed and 0 means that no events are
ready. In case of <code class="function">sd_event_dispatch</code> a
positive value means that the loop is again in the initial state
and 0 means the loop is finished. For any of those functions, a
negative return value means the loop must be aborted.</p></div><div class="refsect1"><a name="idm140719517784720"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-EINVAL"><span class="term"><code class="constant">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>Parameter <em class="parameter"><code>event</code></em> is
<code class="constant">NULL</code>.</p></dd><dt id="-EBUSY"><span class="term"><code class="constant">-EBUSY</code></span><a class="headerlink" title="Permalink to this term" href="#-EBUSY">¶</a></dt><dd><p>The event loop object is not in the right
state.</p></dd><dt id="-ESTALE"><span class="term"><code class="constant">-ESTALE</code></span><a class="headerlink" title="Permalink to this term" href="#-ESTALE">¶</a></dt><dd><p>The event loop is already terminated.</p></dd><dt id="-ECHILD"><span class="term"><code class="constant">-ECHILD</code></span><a class="headerlink" title="Permalink to this term" href="#-ECHILD">¶</a></dt><dd><p>The event loop has been created in a different process.</p></dd></dl></div><p>Other errors are possible too.</p></div><div class="refsect1"><a name="idm140719517776160"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>Functions described here are available
as a shared library, which can be compiled and linked to with the
<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm140719517773488"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd_event_new.html"><span class="citerefentry"><span class="refentrytitle">sd_event_new</span>(3)</span></a>,
<a href="sd_event_run.html"><span class="citerefentry"><span class="refentrytitle">sd_event_run</span>(3)</span></a>,
<a href="sd_event_add_io.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_io</span>(3)</span></a>,
<a href="sd_event_add_time.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_time</span>(3)</span></a>,
<a href="sd_event_add_signal.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_signal</span>(3)</span></a>,
<a href="sd_event_add_defer.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_defer</span>(3)</span></a>,
<a href="sd_event_add_exit.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_exit</span>(3)</span></a>,
<a href="sd_event_add_post.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_post</span>(3)</span></a>.
</p></div></div></body></html>
|
