sd_event_source_set_floating(3) — Linux manual page



NAME         top

       sd_event_source_set_floating, sd_event_source_get_floating - Set
       or retrieve 'floating' state of event sources

SYNOPSIS         top

       #include <systemd/sd-event.h>

       int sd_event_source_set_floating(sd_event_source *source,
                                        int floating);

       int sd_event_source_get_floating(sd_event_source *source);

DESCRIPTION         top

       sd_event_source_set_floating() takes a boolean and sets the
       'floating' state of the specified event source object. This is
       used to change the direction of reference counts for the object
       and the event loop it is associated with. In non-floating mode,
       the event source object holds a reference to the event loop
       object, but not vice versa. The creator of the event source
       object must hold a reference to it as long as the source should
       exist. In floating mode, the event loop holds a reference to the
       source object, and will decrease the reference count when being
       freed. This means that a reference to the event loop should be
       held to prevent both from being destroyed.

       Various calls that allocate event source objects (i.e.
       sd_event_add_io(3), sd_event_add_time(3) and similar) will
       automatically set an event source object to 'floating' mode if
       the caller passed NULL in the parameter used to return a
       reference to the event source object. Nevertheless, it may be
       necessary to gain temporary access to the source object, for
       example to adjust event source properties after allocation (e.g.
       its priority or description string). In those cases the object
       may be created in non-floating mode, and the returned reference
       used to adjust the properties, and the object marked as floating
       afterwards, and the reference in the caller dropped.

       sd_event_source_get_floating() may be used to query the current
       'floating' state of the event source object source. It returns
       zero if 'floating' mode is off, positive if it is on.

RETURN VALUE         top

       On success, sd_event_source_set_floating() and
       sd_event_source_get_floating() return a non-negative integer. On
       failure, they return a negative errno-style error code.

       Returned errors may indicate the following problems:

           source is not a valid pointer to an sd_event_source object.

           The event loop has been created in a different process.

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),

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2021-04-01.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-01.)  If you discover any rendering
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       (which is not part of the original manual page), send a mail to

systemd 248                              SD_EVENT_SOURCE_SET_FLOATING(3)

Pages that refer to this page: sd_event_add_child(3)sd_event_add_defer(3)sd_event_add_inotify(3)sd_event_add_io(3)sd_event_add_signal(3)sd_event_add_time(3)systemd.directives(7)systemd.index(7)