SD_EVENT_RUN

sd_event_loop() invokes sd_event_run() in a loop, thus implementing the actual event loop. The call returns as soon as exiting was requested using sd_event_exit(3).

The event loop object event is created with sd_event_new(3). Events sources to wait for and their handlers may be registered with sd_event_add_io(3), sd_event_add_time(3), sd_event_add_signal(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_post(3) and sd_event_add_exit(3).

For low-level control of event loop execution, use sd_event_prepare(3), sd_event_wait(3) and sd_event_dispatch(3) which are wrapped by sd_event_run(). Along with sd_event_get_fd(3), these functions allow integration of an sd-event(3) event loop into foreign event loop implementations.  

RETURN VALUE

On failure, these functions return a negative errno-style error code. sd_event_run() returns a positive, non-zero integer if an event source was dispatched, and zero when the specified timeout hit before an event source has seen any event, and hence no event source was dispatched. sd_event_loop() returns the exit code specified when invoking sd_event_exit().  

Errors

Returned errors may indicate the following problems:

-EINVAL

The event parameter is invalid or NULL.

-EBUSY

The event loop object is not in the right state (see sd_event_prepare(3) for an explanation of possible states).

-ESTALE

The event loop is already terminated.

-ECHILD

The event loop has been created in a different process.

Other errors are possible, too.  

NOTES

These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.  

SEE ALSO

systemd(1), sd-event(3), sd_event_new(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_exit(3), sd_event_get_fd(3), sd_event_wait(3), m[blue]GLib Main Event Loopm[][1]  

NOTES

1.

GLib Main Event Loop

https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html