sd_bus_attach_event, sd_bus_detach_event, sd_bus_get_event — Attach a bus connection object to an event loop
#include <systemd/sd-bus.h>
int sd_bus_attach_event( | sd_bus *bus, |
sd_event *e, | |
int priority) ; |
int sd_bus_detach_event( | sd_bus *bus) ; |
sd_event *sd_bus_get_event( | sd_bus *bus) ; |
sd_bus_attach_event()
attaches the specified bus connection object to an
sd-event(3) event loop object at
the specified priority (see
sd_event_source_set_priority(3)
for details on event loop priorities). When a bus connection object is attached to an event loop incoming messages
will be automatically read and processed, and outgoing messages written, whenever the event loop is run. When the
event loop is about to terminate, the bus connection is automatically flushed and closed (see
sd_bus_set_close_on_exit(3) for
details on this). By default bus connection objects are not attached to any event loop. When a bus connection
object is attached to one it is not necessary to invoke
sd_bus_wait(3) or
sd_bus_process(3) as this
functionality is handled automatically by the event loop.
sd_bus_detach_event()
detaches a bus object from its event loop.
The sd_bus_get_event()
returns the event loop object the specified bus object is
currently attached to, or NULL
if it is currently not attached to any.
Note that sd_bus_attach_event()
is only one of three supported ways to implement I/O
event handling for bus connections. Alternatively use
sd_bus_get_fd(3) for hooking up a
bus connection object with external or manual event loops. Or use
sd_bus_wait(3) as a simple
synchronous, blocking I/O waiting call.
On success, sd_bus_attach_event()
and sd_bus_detach_event()
return
0 or a positive integer. On failure, they return a negative errno-style error code.
sd_bus_get_event()
returns an event loop object or NULL
.
Functions described here are available as a shared
library, which can be compiled against and linked to with the
libsystemd
pkg-config(1)
file.
The code described here uses
getenv(3),
which is declared to be not multi-thread-safe. This means that the code calling the functions described
here must not call
setenv(3)
from a parallel thread. It is recommended to only do calls to setenv()
from an early phase of the program when no other threads have been started.
sd_bus_attach_event()
,
sd_bus_detach_event()
, and
sd_bus_get_event()
were added in version 221.