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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | NOTES | COLOPHON |
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SD_EVENT_SOURCE_UNREF(3) sd_event_source_unref SD_EVENT_SOURCE_UNREF(3)
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
#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);
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.
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.
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_event_source_unref(), sd_event_source_unrefp(), and
sd_event_source_ref() were added in version 229.
sd_event_source_disable_unref() and
sd_event_source_disable_unrefp() were added in version 243.
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)
1. Clean-up Variable Attribute
https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SD_EVENT_SOURCE_UNREF(3)
Pages that refer to this page: sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_memory_pressure(3), sd_event_add_signal(3), sd_event_add_time(3), sd_event_source_get_pending(3), sd_event_source_set_enabled(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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