|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON |
SD_EVENT_SOURCE_SET_ENABLED(3)ent_source_set_enabledNT_SOURCE_SET_ENABLED(3)
sd_event_source_set_enabled, sd_event_source_get_enabled,
SD_EVENT_ON, SD_EVENT_OFF, SD_EVENT_ONESHOT - Enable or disable event
sources
#include <systemd/sd-event.h>
enum {
SD_EVENT_OFF = 0,
SD_EVENT_ON = 1,
SD_EVENT_ONESHOT = -1,
};
int sd_event_source_set_enabled(sd_event_source *source,
int enabled);
int sd_event_source_get_enabled(sd_event_source *source,
int *enabled);
sd_event_source_set_enabled() may be used to enable or disable the
event source object specified as source. The enabled parameter takes
one of SD_EVENT_ON (to enable), SD_EVENT_OFF (to disable) or
SD_EVENT_ONESHOT. If invoked with SD_EVENT_ONESHOT the event source
will be enabled but automatically reset to SD_EVENT_OFF after the
event source was dispatched once.
Event sources that are disabled will not result in event loop wakeups
and will not be dispatched, until they are enabled again.
sd_event_source_get_enabled() may be used to query whether the event
source object source is currently enabled or not. It returns the
enablement state in enabled.
Event source objects are enabled when they are first created with
calls such as sd_event_add_io(3), sd_event_add_time(3). However,
depending on the event source type they are enabled continuously
(SD_EVENT_ON) or only for a single invocation of the event source
handler (SD_EVENT_ONESHOT). For details see the respective manual
pages.
As event source objects stay active and may be dispatched as long as
there is at least one reference to them, in many cases it is a good
idea to combine a call to sd_event_source_unref(3) with a prior call
to sd_event_source_set_enabled() with SD_EVENT_OFF, to ensure the
event source is not dispatched again until all other remaining
references are dropped.
On success, sd_event_source_set_enabled() and
sd_event_source_get_enabled() return a non-negative integer. On
failure, they return a negative errno-style error code.
Returned errors may indicate the following problems:
-EINVAL
source is not a valid pointer to an sd_event_source object.
-ENOMEM
Not enough memory.
-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_child(3), sd_event_add_signal(3), sd_event_add_defer(3),
sd_event_source_unref(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 2017-07-05. If you dis‐
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you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
systemd 234 SD_EVENT_SOURCE_SET_ENABLED(3)
Pages that refer to this page: sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_io(3), sd_event_add_signal(3), sd_event_add_time(3), sd_event_source_set_prepare(3), sd_event_source_unref(3), systemd.directives(7), systemd.index(7)