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

       The sd_bus_message_get_monotonic_usec(), sd_bus_message_get_realtime_usec(), and
       sd_bus_message_get_seqnum() interfaces are available as a shared library, which can be
       compiled and linked to with the libsystemd pkg-config(1) file.

SEE ALSO

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