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authorLennart Poettering <lennart@poettering.net>2014-04-13 17:42:11 -0700
committerLennart Poettering <lennart@poettering.net>2014-04-13 17:42:11 -0700
commit6e0369b0ff3909baec25c6ab31b5ddf5c4ae0f3f (patch)
tree4bd28fc55254bd5602b5379903a0dbf6182e70f2
parent11fb37f16ed99c1603c9d770b60ce4953b96a58d (diff)
man: explain that the timestamps on incoming kdbus messages are not necessarily monotonically increasing
-rw-r--r--man/sd_bus_message_get_monotonic_usec.xml13
1 files changed, 10 insertions, 3 deletions
diff --git a/man/sd_bus_message_get_monotonic_usec.xml b/man/sd_bus_message_get_monotonic_usec.xml
index 683931c4da..0a11a31230 100644
--- a/man/sd_bus_message_get_monotonic_usec.xml
+++ b/man/sd_bus_message_get_monotonic_usec.xml
@@ -92,9 +92,10 @@
<para><function>sd_bus_message_get_seqnum()</function>
returns the kernel-assigned sequence number of the
- message. The kernel assigns a global monotonically increasing
- sequence number to all messages sent on the local
- system. This sequence number is useful for determining
+ 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 busses of
the local system. The sequence number combined with
the boot ID of the system (as returned by
@@ -102,6 +103,12 @@
is a suitable globally unique identifier for bus
messages.</para>
+ <para>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.</para>
+
<para>These timestamps and the sequence number are
attached to each message by the kernel and cannot be
manipulated by the sender.</para>