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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_EVEN...LOATING(3) sd_event_source_set_floating SD_EVEN...LOATING(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.
Added in version 244.
-ECHILD
The event loop has been created in a different process,
library or module instance.
Added in version 244.
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_set_floating() and sd_event_source_get_floating()
were added in version 244.
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)
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 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) 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
[email protected]
systemd 257~devel SD_EVEN...LOATING(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_memory_pressure(3), sd_event_add_signal(3), sd_event_add_time(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2024-06-26 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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