sd_event_source_get_pending - Man Page
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.
All functions listed here are thread-agnostic and only a single thread may operate on a given object at any given time. Different threads may access the same object at different times. Multiple independent objects may be used from different threads in parallel.
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)