x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_EVENT_SOURCE_SET_FLOATsd_event_source_set_flSD_EVENT_SOURCE_SET_FLOATING(3)
NAME
sd_event_source_set_floating, sd_event_source_get_floating - Set or
retrieve 'floating' state of event sources
SYNOPSIS
#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
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
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, library or
module instance.
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_description(3),
sd_event_source_set_priority(3)
systemd 254 SD_EVENT_SOURCE_SET_FLOATING(3)
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