SD_BUS_MESSAGE_GET_MONOsd_bus_message_get_SD_BUS_MESSAGE_GET_MONOTONIC_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
       These APIs are implemented 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)

systemd 252                               SD_BUS_MESSAGE_GET_MONOTONIC_USEC(3)

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