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author | Lennart Poettering <lennart@poettering.net> | 2017-12-20 16:31:58 +0100 |
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committer | Lennart Poettering <lennart@poettering.net> | 2018-01-05 13:58:33 +0100 |
commit | d97eac36d889a43bc71dcc9d43f8b6e536dddaae (patch) | |
tree | d2214f39ba0edc579fe345b1ae5b6ac8993c3363 /man/sd_bus_add_match.xml | |
parent | 51b13863a2d64fa7c8da8006c4d345e08f9986c2 (diff) | |
download | systemd-d97eac36d889a43bc71dcc9d43f8b6e536dddaae.tar.gz |
man: document all the new APIs we added
Diffstat (limited to 'man/sd_bus_add_match.xml')
-rw-r--r-- | man/sd_bus_add_match.xml | 137 |
1 files changed, 102 insertions, 35 deletions
diff --git a/man/sd_bus_add_match.xml b/man/sd_bus_add_match.xml index 4772c738ac..f11d078284 100644 --- a/man/sd_bus_add_match.xml +++ b/man/sd_bus_add_match.xml @@ -45,8 +45,11 @@ <refnamediv> <refname>sd_bus_add_match</refname> + <refname>sd_bus_add_match_async</refname> + <refname>sd_bus_match_signal</refname> + <refname>sd_bus_match_signal_async</refname> - <refpurpose>Add a match rule for message dispatching</refpurpose> + <refpurpose>Add a match rule for incoming message dispatching</refpurpose> </refnamediv> <refsynopsisdiv> @@ -54,6 +57,13 @@ <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> <funcprototype> + <funcdef>typedef int (*<function>sd_bus_message_handler_t</function>)</funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef> + </funcprototype> + + <funcprototype> <funcdef>int <function>sd_bus_add_match</function></funcdef> <paramdef>sd_bus *<parameter>bus</parameter></paramdef> <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef> @@ -63,57 +73,111 @@ </funcprototype> <funcprototype> - <funcdef>typedef int (*<function>sd_bus_message_handler_t</function>)</funcdef> - <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + <funcdef>int <function>sd_bus_add_match_async</function></funcdef> + <paramdef>sd_bus *<parameter>bus</parameter></paramdef> + <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef> + <paramdef>const char *<parameter>match</parameter></paramdef> + <paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef> + <paramdef>sd_bus_message_handler_t <parameter>install_callback</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_bus_match_signal</function></funcdef> + <paramdef>sd_bus *<parameter>bus</parameter></paramdef> + <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef> + <paramdef>const char *<parameter>sender</parameter></paramdef> + <paramdef>const char *<parameter>path</parameter></paramdef> + <paramdef>const char *<parameter>interface</parameter></paramdef> + <paramdef>const char *<parameter>member</parameter></paramdef> + <paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_bus_match_signal_async</function></funcdef> + <paramdef>sd_bus *<parameter>bus</parameter></paramdef> + <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef> + <paramdef>const char *<parameter>sender</parameter></paramdef> + <paramdef>const char *<parameter>path</parameter></paramdef> + <paramdef>const char *<parameter>interface</parameter></paramdef> + <paramdef>const char *<parameter>member</parameter></paramdef> + <paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef> + <paramdef>sd_bus_message_handler_t <parameter>install_callback</parameter></paramdef> <paramdef>void *<parameter>userdata</parameter></paramdef> - <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef> </funcprototype> + </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> - <para> - <function>sd_bus_add_match()</function> installs a match rule for incoming messages received on the specified bus - connection object <parameter>bus</parameter>. The syntax of the match rule expression passed in - <parameter>match</parameter> is described in the <ulink - url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus Specification</ulink>. The specified handler - function <parameter>callback</parameter> is called for eaching incoming message matching the specified - expression, the <parameter>userdata</parameter> parameter is passed as-is to the callback function. + <para><function>sd_bus_add_match()</function> installs a match rule for messages received on the specified bus + connection object <parameter>bus</parameter>. The syntax of the match rule expression passed in + <parameter>match</parameter> is described in the <ulink + url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus Specification</ulink>. The specified handler + function <parameter>callback</parameter> is called for eaching incoming message matching the specified expression, + the <parameter>userdata</parameter> parameter is passed as-is to the callback function. The match is installed + synchronously when connected to a bus broker, i.e. the call sends a control message requested the match to be added + to the broker and waits until the broker confirms the match has been installed successfully.</para> + + <para><function>sd_bus_add_match_async()</function> operates very similar to + <function>sd_bus_match_signal()</function>, however it installs the match asynchronously, in a non-blocking + fashion: a request is sent to the broker, but the call does not wait for a response. The + <parameter>install_callback</parameter> function is called when the response is later received, with the response + message from the broker as parameter. If this function is specified as <constant>NULL</constant> a default + implementation is used that terminates the bus connection should installing the match fail.</para> + + <para><function>sd_bus_match_signal()</function> is very similar to <function>sd_bus_add_match()</function>, but + only matches signals, and instead of a match expression accepts four parameters: <parameter>sender</parameter> (the + service name of the sender), <parameter>path</parameter> (the object path of the emitting object), + <parameter>interface</parameter> (the interface the signal belongs to), <parameter>member</parameter> (the signal + name), from which the match string is internally generated. Optionally, these parameters may be specified as + <constant>NULL</constant> in which case the relevant field of incoming signals is not tested.</para> + + <para><function>sd_bus_match_signal_async()</function> is combines the signal matching logic of + <function>sd_bus_match_signal()</function> with the asynchronous behaviour of + <function>sd_bus_add_match_async()</function>.</para> + + <para>On success, and if non-<constant>NULL</constant>, the <parameter>slot</parameter> return parameter will be + set to a slot object that may be used as a reference to the installed match, and may be utilized to remove it again + at a later time with + <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If specified + as <constant>NULL</constant> the lifetime of the match is bound to the lifetime of the bus object itself, and the + match cannot be removed independently.</para> + + <para>The message <parameter>m</parameter> passed to the callback is only borrowed, that is, the callback should + not call <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> + on it. If the callback wants to hold on to the message beyond the lifetime of the callback, it needs to call + <citerefentry><refentrytitle>sd_bus_message_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry> to create a + new reference.</para> + + <para>If an error occurs during the callback invocation, the callback should return a negative error number + (optionally, a more precise error may be returned in <parameter>ret_error</parameter>, as well). If it wants other + callbacks that match the same rule to be called, it should return 0. Otherwise it should return a positive integer. </para> - <para> - On success, and if non-<constant>NULL</constant>, the <parameter>slot</parameter> return parameter will be set to - a slot object that may be used as a reference to the installed match, and may be utilized to remove it again at a - later time with - <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If - specified as <constant>NULL</constant> the lifetime of the match is bound to the lifetime of the bus object itself, and the match - cannot be removed independently. - </para> + <para>If the <parameter>bus</parameter> refers to a direct connection (i.e. not a bus connection, as set with + <citerefentry><refentrytitle>sd_bus_set_bus_client</refentrytitle><manvolnum>3</manvolnum></citerefentry>) the + match is only installed on the client side, and the synchronous and asynchronous functions operate the same.</para> + </refsect1> - <para> - The message <parameter>m</parameter> passed to the callback is only borrowed, that is, the callback should not - call <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> on - it. If the callback wants to hold on to the message beyond the lifetime of the callback, it needs to call - <citerefentry><refentrytitle>sd_bus_message_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry> to create - a new reference. - </para> + <refsect1> + <title>Return Value</title> <para> - If an error occurs during the callback invocation, the callback should return a negative error number. If it - wants other callbacks that match the same rule to be called, it should return 0. Otherwise it should return a - positive integer. + On success, <function>sd_bus_add_match()</function> and the other calls return 0 or a positive integer. On + failure, they return a negative errno-style error code. </para> </refsect1> <refsect1> - <title>Return Value</title> + <title>Notes</title> - <para> - On success, <function>sd_bus_add_match()</function> returns 0 or a positive integer. On failure, it returns a - negative errno-style error code. - </para> + <para><function>sd_bus_add_match()</function> and the other 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> <refsect1> @@ -121,7 +185,10 @@ <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, - <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry> + <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_set_bus_client</refentrytitle><manvolnum>3</manvolnum></citerefentry> </para> </refsect1> |