Ensure we hold a read lock to check hosts
Ensure we hold a read lock to check hosts

When the policy is checking the length of the host list in
roundRobinHostPolicy ensure that we hold the read lock so that
if SetHosts is called we dont data race.

matope/gocql,i/gocql,adamweiner/gocql,hackintoshrao/gocql,znly/gocql,hackintoshrao/gocql,retailnext/gocql,aai/gocql,gocql/gocql,tempbottle/gocql,lytics/gocql,lytics/gocql,lytics/gocql,aai/gocql,nikandfor/gocql,gcnonato/gocql,revinate/gocql,ChannelMeter/gocql,nikandfor/gocql,adamweiner/gocql,ChannelMeter/gocql,gocql/gocql,kelwang/gocql,Zariel/gocql,tempbottle/gocql,relops/gocql,znly/gocql,gcnonato/gocql,gus/gocql,tempbottle/gocql,relops/gocql,retailnext/gocql,gus/gocql,mondough/gocql,nikandfor/gocql,mailgun/gocql,CrowdSurge/gocql,retailnext/gocql,kelwang/gocql,revinate/gocql,mondough/gocql,mondough/gocql,brandscreen/gocql,matope/gocql,CrowdSurge/gocql,mailgun/gocql,hackintoshrao/gocql,Zariel/gocql,vrischmann/gocql,kelwang/gocql,brandscreen/gocql,i/gocql,relops/gocql,vrischmann/gocql,adamweiner/gocql,gcnonato/gocql,matope/gocql,brandscreen/gocql