We make multiple attempts to mark a node as alive. We do that be
sending an EchoMessage, and marking the node as alive upon receiving a
successful answer. In case there's a network partition and the nodes
can't reach each other, multiple messages may be delivered and
processed.
We can avoid processing duplicate EchoMessage replies by checking
whether we had already marked the node as alive.
Fixes#1184
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180428191942.31990-1-duarte@scylladb.com>
b1dd1876e5