sd_event_now - Man Page

#include <systemd/sd-event​.h>

int sd_event_now(sd_event *event, clockid_t clock, uint64_t *ret);

sd_event_now() returns the time when the most recent event loop iteration began​. A timestamp is taken right after returning from the event sleep, and before dispatching any event sources​. The event parameter specifies the event loop object to retrieve the timestamp from​. The clock parameter specifies the clock to retrieve the timestamp for, and is one of CLOCK_REALTIME (or equivalently CLOCK_REALTIME_ALARM), CLOCK_MONOTONIC, or CLOCK_BOOTTIME (or equivalently CLOCK_BOOTTIME_ALARM), see clock_gettime(2) for more information on the various clocks​. The retrieved timestamp is stored in the ret parameter, in μs since the clock's epoch​. If this function is invoked before the first event loop iteration, the current time is returned, as reported by clock_gettime()​. To distinguish this case from a regular invocation the return value will be positive, and zero when the returned timestamp refers to an actual event loop iteration​.

If the first event loop iteration has not run yet sd_event_now() writes current time to ret and returns a positive return value​. Otherwise, it will write the requested timestamp to ret and return 0​. On failure, the call returns a negative errno-style error code​.

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​.

sd_event_now() was added in version 229​.

systemd(1), sd-event(3), sd_event_new(3), sd_event_add_time(3), clock_gettime(2)

sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_signal(3), sd_event_add_time(3), systemd.directives(7), systemd.index(7).