|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_EVENT_SOURCE_SET_FLOATING(3)t_source_set_floatingT_SOURCE_SET_FLOATING(3)
sd_event_source_set_floating, sd_event_source_get_floating - Set or
retrieve 'floating' state of event sources
#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);
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.
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.
Errors
Returned errors may indicate the following problems:
-EINVAL
source is not a valid pointer to an sd_event_source object.
-ECHILD
The event loop has been created in a different process.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
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_description(3), sd_event_source_set_priority(3)
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systemd 246 SD_EVENT_SOURCE_SET_FLOATING(3)
Pages that refer to this page: 30-systemd-environment-d-generator(7) , systemd.index(7)