public interface LatencyTracker
 An implementaion of this interface can be registered against a Cluster
 object trough the Cluster.register(com.datastax.driver.core.Host.StateListener) method, after which the
 update will be called after each query of the driver to a Cassandra
 host with the latency/duration (in nanoseconds) of this operation.
void update(Host host, long newLatencyNanos)
Note that there is no guarantee that this method won't be called concurrently by multiple thread, so implementations should synchronize internally if need be.
host - the Cassandra host on which a request has been performed.newLatencyNanos - the latency in nanoseconds of the operation. This
 latency corresponds to the time elapsed between when the query was send
 to host and when the response was received by the driver (or the
 operation timeoued, in which newLatencyNanos will approximately
 be the timeout value).Copyright © 2014. All Rights Reserved.