man: fully document sd-event interfaces

This completes the set of man pages for sd-event and contains some minor
other fixes for other man pages too.

The sd_event_set_name(3) man page is renamed to
sd_event_source_set_description(3), which is the correct name of the
concept today.

1 files changed, 63 insertions, 38 deletions

diff --git a/man/sd_event_add_defer.xml b/man/sd_event_add_defer.xml
index 826f2fd224..6a13ede76e 100644
--- a/man/sd_event_add_defer.xml
+++ b/man/sd_event_add_defer.xml
@@ -21,7 +21,7 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
 
-<refentry id="sd_event_add_defer">
+<refentry id="sd_event_add_defer" xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
     <title>sd_event_add_defer</title>
@@ -46,13 +46,22 @@
     <refname>sd_event_add_defer</refname>
     <refname>sd_event_add_post</refname>
     <refname>sd_event_add_exit</refname>
+    <refname>sd_event_handler_t</refname>
 
     <refpurpose>Add static event sources to an event loop</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
     <funcsynopsis>
-      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
+      <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_event_handler_t</function>)</funcdef>
+        <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
 
       <funcprototype>
         <funcdef>int <function>sd_event_add_defer</function></funcdef>
@@ -78,49 +87,67 @@
         <paramdef>void *<parameter>userdata</parameter></paramdef>
       </funcprototype>
 
-      <funcprototype>
-        <funcdef>typedef int (*<function>sd_event_handler_t</function>)</funcdef>
-        <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
-        <paramdef>void *<parameter>userdata</parameter></paramdef>
-      </funcprototype>
-
     </funcsynopsis>
   </refsynopsisdiv>
 
   <refsect1>
     <title>Description</title>
 
-    <para>These three functions add new event sources to an event loop
-    object. The event loop is specified in
-    <parameter>event</parameter>, the event source is returned in the
-    <parameter>source</parameter> parameter. The event sources are
-    enabled statically and will "fire" when the event loop is run and
-    the conditions described below are met. The handler function will
-    be passed the <parameter>userdata</parameter> pointer, which may
-    be chosen freely by the caller.</para>
+    <para>These three functions add new static event sources to an
+    event loop. The event loop object is specified in the
+    <parameter>event</parameter> parameter, the event source object is
+    returned in the <parameter>source</parameter> parameter. The event
+    sources are enabled statically and will "fire" when the event loop
+    is run and the conditions described below are met. The handler
+    function will be passed the <parameter>userdata</parameter>
+    pointer, which may be chosen freely by the caller.</para>
 
     <para><function>sd_event_add_defer()</function> adds a new event
-    source that will "fire" the next time the event loop is run. By
-    default, the handler will be called once
-    (<constant>SD_EVENT_ONESHOT</constant>).</para>
+    source that will be dispatched instantly, before the event loop
+    goes to sleep again and waits for new events. By default, the
+    handler will be called once
+    (<constant>SD_EVENT_ONESHOT</constant>). Note that if the event
+    source is set to <constant>SD_EVENT_ON</constant> the event loop
+    will never go to sleep again, but continously call the handler,
+    possibly interleaved with other event sources.</para>
 
     <para><function>sd_event_add_post()</function> adds a new event
-    source that will "fire" if any event handlers are invoked whenever
-    the event loop is run. By default, the source is enabled
-    permanently (<constant>SD_EVENT_ON</constant>).</para>
+    source that is run before the event loop will sleep and wait
+    for new events, but only after at least one other non-post event
+    source was dispatched. By default, the source is enabled
+    permanently (<constant>SD_EVENT_ON</constant>). Note that this
+    event source type will still allow the event loop to go to sleep
+    again, even if set to <constant>SD_EVENT_ON</constant>, as long as
+    no other event source is ever triggered.</para>
 
     <para><function>sd_event_add_exit()</function> adds a new event
-    source that will "fire" when the event loop is terminated
-    with <function>sd_event_exit()</function>.</para>
+    source that will be dispatched when the event loop is terminated
+    with <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 
     <para>The
     <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     function may be used to enable the event source permanently
     (<constant>SD_EVENT_ON</constant>) or to make it fire just once
-    (<constant>SD_EVENT_ONESHOT</constant>). If the handler function
-    returns a negative error code, it will be disabled after the
-    invocation, even if <constant>SD_EVENT_ON</constant> mode is
-    set.</para>
+    (<constant>SD_EVENT_ONESHOT</constant>).</para>
+
+    <para>If the handler function returns a negative error code, it
+    will be disabled after the invocation, even if the
+    <constant>SD_EVENT_ON</constant> mode was requested before.</para>
+
+    <para>To destroy an event source object use
+    <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+    but note that the event source is only removed from the event loop
+    when all references to the event source are dropped. To make sure
+    an event source does not fire anymore, even when there's still a
+    reference to it kept, consider setting the event source to
+    <constant>SD_EVENT_OFF</constant> with
+    <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+    <para>If the second parameter of these functions is passed as
+    NULL no reference to the event source object is returned. In this
+    case the event source is considered "floating", and will be
+    destroyed implicitly when the event loop itself is
+    destroyed.</para>
   </refsect1>
 
   <refsect1>
@@ -164,15 +191,7 @@
     </variablelist>
   </refsect1>
 
-  <refsect1>
-    <title>Notes</title>
-
-    <para>Functions described here are available as a shared library,
-    which can be compiled and linked to with the
-    <constant>libsystemd</constant> <citerefentry
-    project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-    file.</para>
-  </refsect1>
+  <xi:include href="libsystemd-pkgconfig.xml" />
 
   <refsect1>
     <title>See Also</title>
@@ -181,10 +200,16 @@
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_now</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+      <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     </para>
   </refsect1>