noble (3) sd_event_source_get_pending.3.gz

NAME

       sd_event_source_get_pending - Determine pending state of event sources

SYNOPSIS

       #include <systemd/sd-event.h>

       int sd_event_source_get_pending(sd_event_source *source);

DESCRIPTION

       sd_event_source_get_pending() may be used to determine whether the event source object specified as
       source has seen events but has not been dispatched yet (and thus is marked "pending").

       Event source objects initially are not marked pending, when they are created with calls such as
       sd_event_add_io(3), sd_event_add_time(3), with the exception of those created with sd_event_add_defer(3)
       which are immediately marked pending, and sd_event_add_exit(3) for which the "pending" concept is not
       defined. For details see the respective manual pages.

       In each event loop iteration one event source of those marked pending is dispatched, in the order defined
       by the event source priority, as set with sd_event_source_set_priority(3).

       For I/O event sources, as created with sd_event_add_io(3), the call sd_event_source_get_io_revents(3) may
       be used to query the type of event pending in more detail.

RETURN VALUE

       On success, sd_event_source_get_pending() returns an integer greater than zero when the event source is
       marked pending, and zero when the event source is not marked pending. On failure, it returns 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.

       -EDOM
           source refers to an event source object created with sd_event_add_exit(3).

       -ENOMEM
           Not enough memory.

       -ESTALE
           The event loop is already terminated.

       -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.

HISTORY

       sd_event_source_get_pending() was added in version 229.

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_unref(3)