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Diffstat (limited to 'man/sd_event_add_io.xml')
| -rw-r--r-- | man/sd_event_add_io.xml | 92 |
1 files changed, 46 insertions, 46 deletions
diff --git a/man/sd_event_add_io.xml b/man/sd_event_add_io.xml index eeb406ba5b..c3749164cd 100644 --- a/man/sd_event_add_io.xml +++ b/man/sd_event_add_io.xml @@ -120,36 +120,35 @@ 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 @@ -164,16 +163,17 @@ <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 @@ -181,24 +181,24 @@ 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_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 @@ -214,15 +214,15 @@ 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> @@ -230,13 +230,13 @@ <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> |