sd_event_source_get_pending — Determine pending state of event sources
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.
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.
Returned errors may indicate the following problems:
These APIs are implemented as a shared
library, which can be compiled and linked to with the