# sd_bus_message_get_monotonic_usec

## 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.
    


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