sd_bus_message_get_monotonic_usec(3) — Linux manual page

SD_BUS...IC_USEC(3) sd_bus_message_get_monotonic_usecSD_BUS...IC_USEC(3)

NAME

       sd_bus_message_get_monotonic_usec,
       sd_bus_message_get_realtime_usec, sd_bus_message_get_seqnum -
       Retrieve the sender timestamps and sequence number of a message

SYNOPSIS

       #include <systemd/sd-bus.h>

       int sd_bus_message_get_monotonic_usec(sd_bus_message *message,
                                             uint64_t *usec);

       int sd_bus_message_get_realtime_usec(sd_bus_message *message,
                                            uint64_t *usec);

       int sd_bus_message_get_seqnum(sd_bus_message *message,
                                     uint64_t *seqnum);

DESCRIPTION

       sd_bus_message_get_monotonic_usec() returns the monotonic
       timestamp of the time the message was sent. This value is in
       microseconds since the CLOCK_MONOTONIC epoch, see
       clock_gettime(2) for details.

       Similarly, sd_bus_message_get_realtime_usec() returns the
       realtime (wallclock) timestamp of the time the message was sent.
       This value is in microseconds since Jan 1st, 1970, i.e. in the
       CLOCK_REALTIME clock.

       sd_bus_message_get_seqnum() returns the kernel-assigned sequence
       number of the message. The kernel assigns a global, monotonically
       increasing sequence number to all messages transmitted on the
       local system, at the time the message was sent. This sequence
       number is useful for determining message send order, even across
       different buses of the local system. The sequence number combined
       with the boot ID of the system (as returned by
       sd_id128_get_boot(3)) is a suitable globally unique identifier
       for bus messages.

       Note that the sending order and receiving order of messages might
       differ, in particular for broadcast messages. This means that the
       sequence number and the timestamps of messages a client reads are
       not necessarily monotonically increasing.

       These timestamps and the sequence number are attached to each
       message by the kernel and cannot be manipulated by the sender.

       Note that these timestamps are only available on some bus
       transports, and only after support for them has been negotiated
       with the sd_bus_negotiate_timestamp(3) call.

RETURN VALUE

       On success, these calls return 0 or a positive integer. On
       failure, these calls return a negative errno-style error code.

       On success, the timestamp or sequence number is returned in the
       specified 64-bit unsigned integer variable.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           A specified parameter is invalid.

       -ENODATA
           No timestamp or sequence number information is attached to
           the passed message. This error is returned if the underlying
           transport does not support timestamping or assigning of
           sequence numbers, or if this feature has not been negotiated
           with sd_bus_negotiate_timestamp(3).

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_bus_message_get_monotonic_usec(),
       sd_bus_message_get_realtime_usec(), and
       sd_bus_message_get_seqnum() were added in version 209.

SEE ALSO

       systemd(1), sd-bus(3), sd_bus_new(3),
       sd_bus_negotiate_timestamp(3), clock_gettime(2),
       sd_id128_get_boot(3)

COLOPHON

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       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-13.)  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
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 257~devel                                    SD_BUS...IC_USEC(3)

Pages that refer to this page: sd-bus(3), sd_bus_negotiate_fds(3), systemd.directives(7), systemd.index(7)

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