sd_journal_get_realtime_usec(3) — Linux manual page



NAME         top

       sd_journal_get_realtime_usec, sd_journal_get_monotonic_usec - Read
       timestamps from the current journal entry

SYNOPSIS         top

       #include <systemd/sd-journal.h>

       int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *usec);

       int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *usec,
                                         sd_id128_t *boot_id);

DESCRIPTION         top

       sd_journal_get_realtime_usec() gets the realtime (wallclock)
       timestamp of the current journal entry. It takes two arguments: the
       journal context object and a pointer to a 64-bit unsigned integer to
       store the timestamp in. The timestamp is in microseconds since the
       epoch, i.e.  CLOCK_REALTIME.

       sd_journal_get_monotonic_usec() gets the monotonic timestamp of the
       current journal entry. It takes three arguments: the journal context
       object, a pointer to a 64-bit unsigned integer to store the timestamp
       in, as well as a 128-bit ID buffer to store the boot ID of the
       monotonic timestamp. The timestamp is in microseconds since boot-up
       of the specific boot, i.e.  CLOCK_MONOTONIC. Since the monotonic
       clock begins new with every reboot, it only defines a well-defined
       point in time when used together with an identifier identifying the
       boot. See sd_id128_get_boot(3) for more information. If the boot ID
       parameter is passed NULL, the function will fail if the monotonic
       timestamp of the current entry is not of the current system boot.

       Note that these functions will not work before sd_journal_next(3) (or
       related call) has been called at least once, in order to position the
       read pointer at a valid entry.

RETURN VALUE         top

       sd_journal_get_realtime_usec() and sd_journal_get_monotonic_usec()
       returns 0 on success or a negative errno-style error code. If the
       boot ID parameter was passed NULL and the monotonic timestamp of the
       current journal entry is not of the current system boot, -ESTALE is
       returned by sd_journal_get_monotonic_usec().

NOTES         top

       All functions listed here are thread-agnostic and only a single
       specific thread may operate on a given object during its entire
       lifetime. It's safe to allocate multiple independent objects and use
       each from a specific thread in parallel. However, it's not safe to
       allocate such an object in one thread, and operate or free it from
       any other, even if locking is used to ensure these threads don't
       operate on it at the very same time.

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       systemd(1), sd-journal(3), sd_journal_open(3), sd_journal_next(3),
       sd_journal_get_data(3), sd_id128_get_boot(3), clock_gettime(2),

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-11.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

systemd 246                                  SD_JOURNAL_GET_REALTIME_USEC(3)

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