x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_EVENT_SOURCE_UNREF(3) sd_event_source_unref SD_EVENT_SOURCE_UNREF(3)
NAME
sd_event_source_unref, sd_event_source_unrefp, sd_event_source_ref,
sd_event_source_disable_unref, sd_event_source_disable_unrefp -
Increase or decrease event source reference counters
SYNOPSIS
#include <systemd/sd-event.h>
sd_event_source* sd_event_source_unref(sd_event_source *source);
void sd_event_source_unrefp(sd_event_source **source);
sd_event_source* sd_event_source_ref(sd_event_source *source);
sd_event_source*
sd_event_source_disable_unref(sd_event_source *source);
void sd_event_source_disable_unrefp(sd_event_source **source);
DESCRIPTION
sd_event_source_unref() may be used to decrement by one the internal
reference counter of the event source object specified as source. The
reference counter is initially set to one, when the event source is
created with calls such as sd_event_add_io(3) or sd_event_add_time(3).
When the reference counter reaches zero, the object is detached from
the event loop object and destroyed.
sd_event_source_unrefp() is similar to sd_event_source_unref() but
takes a pointer to a pointer to an sd_event_source object. This call is
useful in conjunction with GCC's and LLVM's Clean-up Variable
Attribute[1]. Note that this function is defined as inline function.
sd_event_source_ref() may be used to increase by one the internal
reference counter of the event source object specified as source.
sd_event_source_unref(), sd_bus_creds_unrefp() and sd_bus_creds_ref()
execute no operation if the passed event source object is NULL.
Note that event source objects stay alive and may be dispatched as long
as they have a reference counter greater than zero. In order to drop a
reference of an event source and make sure the associated event source
handler function is not called anymore it is recommended to combine a
call of sd_event_source_unref() with a prior call to
sd_event_source_set_enabled() with SD_EVENT_OFF or call
sd_event_source_disable_unref(), see below.
sd_event_source_disable_unref() combines a call to
sd_event_source_set_enabled() with SD_EVENT_OFF with
sd_event_source_unref(). This ensures that the source is disabled
before the local reference to it is lost. The source parameter is
allowed to be NULL.
sd_event_source_disable_unrefp() is similar to
sd_event_source_unrefp(), but in addition disables the source first.
This call is useful in conjunction with GCC's and LLVM's Clean-up
Variable Attribute[1]. Note that this function is defined as inline
function.
RETURN VALUE
sd_event_source_unref() and sd_event_source_disable_unref() always
return NULL. sd_event_source_ref() always returns the event source
object passed in.
NOTES
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.
SEE ALSO
sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
sd_event_add_signal(3), sd_event_add_child(3), sd_event_add_inotify(3),
sd_event_add_defer(3), sd_event_source_set_enabled(3)
NOTES
1. Clean-up Variable Attribute
https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
systemd 254 SD_EVENT_SOURCE_UNREF(3)
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