NAME

       sd_event_now - Retrieve current event loop iteration timestamp

SYNOPSIS

       #include <systemd/sd-event.h>

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

DESCRIPTION

       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 usec
       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.

RETURN VALUE

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

   Errors
       Returned values may indicate the following problems:

       -EINVAL
           An invalid parameter was passed.

       -EOPNOTSUPP
           Unsupported clock type.

       -ECHILD
           The event loop object was 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_now() was added in version 229.

SEE ALSO

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