returned in the <parameter>source</parameter> parameter. The
<parameter>fd</parameter> parameter takes the UNIX file descriptor
to watch, which may refer to a socket, a FIFO, a message queue, a
- serial connection, a character device or any other file descriptor
- compatible with Linux <citerefentry
- project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
- <parameter>events</parameter> parameter takes a bit mask of I/O
- events to watch the file descriptor for, a combination of the
- following event flags: <constant>EPOLLIN</constant>,
- <constant>EPOLLOUT</constant>, <constant>EPOLLRDHUP</constant>,
- <constant>EPOLLPRI</constant> and <constant>EPOLLET</constant>,
- see <citerefentry
- project='man-pages'><refentrytitle>epoll_ctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ serial connection, a character device, or any other file descriptor
+ compatible with Linux
+ <citerefentry project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
+ <parameter>events</parameter> parameter takes a bit mask of events
+ to watch for, a combination of the following event flags:
+ <constant>EPOLLIN</constant>, <constant>EPOLLOUT</constant>,
+ <constant>EPOLLRDHUP</constant>, <constant>EPOLLPRI</constant>,
+ and <constant>EPOLLET</constant>, see
+ <citerefentry project='man-pages'><refentrytitle>epoll_ctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details. The <parameter>handler</parameter> shall reference a
- function to call when the I/O event source is triggered. The
- handler function will be passed the
- <parameter>userdata</parameter> pointer, which may be chosen
- freely by the caller. The handler will also be passed the file
- descriptor the event was seen on as well as the actual event flags
- seen. It's generally a subset of the events watched, however may
- additionally have <constant>EPOLLERR</constant> and
- <constant>EPOLLHUP</constant> set.</para>
-
- <para>By default, the I/O event source will stay enabled
+ function to call when the event source is triggered. The
+ <parameter>userdata</parameter> pointer will be passed to the
+ handler function, and may be chosen freely by the caller. The
+ handler will also be passed the file descriptor the event was seen
+ on, as well as the actual event flags. It's generally a subset of
+ the events watched, however may additionally include
+ <constant>EPOLLERR</constant> and <constant>EPOLLHUP</constant>.
+ </para>
+
+ <para>By default, an event source will stay enabled
continuously (<constant>SD_EVENT_ON</constant>), but this may be
changed with
<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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. Note
- that an I/O event source set to <constant>SD_EVENT_ON</constant> will
- fire continuously unless data is read or written to the file
- descriptor in order to reset the mask of events seen.
+ that an event source set to <constant>SD_EVENT_ON</constant> will
+ fire continuously unless data is read from or written to the file
+ descriptor to reset the mask of events seen.
</para>
<para>Setting the I/O event mask to watch for to 0 does not mean
<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>
+ an event source does not fire anymore, even if it is still referenced,
+ disable the event source using
+ <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ with <constant>SD_EVENT_OFF</constant>.</para>
<para>If the second parameter of
- <function>sd_event_add_io()</function> 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>
+ <function>sd_event_add_io()</function> is
+ <constant>NULL</constant> 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>
<para>It is recommended to use
<function>sd_event_add_io()</function> only in conjunction with
ensure that all I/O operations from invoked handlers are properly
asynchronous and non-blocking. Using file descriptors without
<constant>O_NONBLOCK</constant> might result in unexpected
- starving of other event sources. See <citerefentry
- project='man-pages'><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ starvation of other event sources. See
+ <citerefentry project='man-pages'><refentrytitle>fcntl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details on enabling <constant>O_NONBLOCK</constant> mode.</para>
<para><function>sd_event_source_get_io_events()</function> retrieves
- the configured I/O event mask to watch of an I/O event source created
+ the configured mask of watched I/O events of an event source created
previously with <function>sd_event_add_io()</function>. It takes
the event source object and a pointer to a variable to store the
- event mask in.</para>
+ mask in.</para>
- <para><function>sd_event_source_set_io_events()</function> changes the
- configured I/O event mask to watch of an I/O event source created previously
- with <function>sd_event_add_io()</function>. It takes the event
- source object and the new event mask to set.</para>
+ <para><function>sd_event_source_set_io_events()</function>
+ configures the mask of watched I/O events of an event source created
+ previously with <function>sd_event_add_io()</function>. It takes the
+ event source object and the new event mask.</para>
- <para><function>sd_event_source_get_io_events()</function>
+ <para><function>sd_event_source_get_io_revents()</function>
retrieves the I/O event mask of currently seen but undispatched
- events from an I/O event source created previously with
+ events from an event source created previously with
<function>sd_event_add_io()</function>. It takes the event source
object and a pointer to a variable to store the event mask
in. When called from a handler function on the handler's event
source types, the latter only to I/O event sources.</para>
<para><function>sd_event_source_get_io_fd()</function> retrieves
- the UNIX file descriptor of an I/O event source created previously
+ the UNIX file descriptor of an event source created previously
with <function>sd_event_add_io()</function>. It takes the event
- source object and returns the positive file descriptor in the return
- value, or a negative error number on error (see below).</para>
+ source object and returns the non-negative file descriptor
+ or a negative error number on error (see below).</para>
<para><function>sd_event_source_set_io_fd()</function>
changes the UNIX file descriptor of an I/O event source created
previously with <function>sd_event_add_io()</function>. It takes
- the event source object and the new file descriptor to set.</para>
+ the event source object and the new file descriptor.</para>
</refsect1>
<refsect1>
<para>On success, these functions return 0 or a positive
integer. On failure, they return a negative errno-style error
- code. </para>
+ code.</para>
</refsect1>
<refsect1>
<title>Errors</title>
- <para>Returned errors may indicate the following problems:</para>
+ <para>Returned values may indicate the following problems:</para>
<variablelist>
<varlistentry>
~ianmdlvl / elogind.git / blobdiff