sd_event_new, sd_event_default, sd_event_ref, sd_event_unref — Acquire and release an event loop object
#include <systemd/sd-bus.h>
int sd_event_new( | sd_bus **event) ; |
int sd_event_default( | sd_bus **event) ; |
sd_bus *sd_event_ref( | sd_bus *event) ; |
sd_bus *sd_event_unref( | sd_bus *event) ; |
sd_event_new()
allocates a new event
loop object. The event loop object is returned in the
event
parameter. After use, drop
the returned reference with
sd_event_unref()
. When the last reference is
dropped, the object is freed.
sd_event_default()
acquires a reference
to the default event loop object of the calling thread, possibly
allocating a new object if no default event loop object has been
allocated yet for the thread. After use, drop the returned
reference with sd_event_unref()
. When the
last reference is dropped, the event loop is freed. If this
function is called while the object returned from a previous call
from the same thread is still referenced, the same object is
returned again, but the reference is increased by one. It is
recommended to use this call instead of
sd_event_new()
in order to share event loop
objects between various components that are dispatched in the same
thread. All threads have exactly either zero or one default event loop
objects associated, but never more.
sd_event_ref()
increases the reference
count of the specified event loop object by one.
sd_event_unref()
decreases the
reference count of the specified event loop object by one. If
the count hits zero, the object is freed. Note that it
is freed regardless of whether it is the default event loop object for a
thread or not. This means that allocating an event loop with
sd_event_default()
, then releasing it, and
then acquiring a new one with
sd_event_default()
will result in two
distinct objects. Note that in order to free an event loop object,
all remaining event sources of the event loop also need to be
freed as each keeps a reference to it.
On success, sd_event_new()
and
sd_event_default()
return 0 or a positive
integer. On failure, they return a negative errno-style error
code. sd_event_ref()
always returns a pointer
to the event loop object passed
in. sd_event_unref()
always returns
NULL
.
sd_event_new()
and the other functions
described here are available as a shared library, which can be
compiled and linked to with the
libsystemd
pkg-config(1)
file.