sd_event_source_unref(3) — Linux manual page


SD_EVENT_SOURCE_UNREF(3)    sd_event_source_unref   SD_EVENT_SOURCE_UNREF(3)

NAME         top

       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         top

       #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_disable_unref(sd_event_source *source);

       void sd_event_source_disable_unrefp(sd_event_source **source);

DESCRIPTION         top

       sd_event_source_unref() may be used to decrement by one the 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 it is removed from its 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 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

RETURN VALUE         top

       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         top

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       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),

NOTES         top

        1. Clean-up Variable Attribute

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-11.)  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

systemd 246                                         SD_EVENT_SOURCE_UNREF(3)

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