org.apache.zookeeper.client

Interface HostProvider

All Known Implementing Classes:

StaticHostProvider

@InterfaceAudience.Public
public interface HostProvider

A set of hosts a ZooKeeper client should connect to. Classes implementing this interface must guarantee the following: * Every call to next() returns an InetSocketAddress. So the iterator never ends. * The size() of a HostProvider may never be zero. A HostProvider must return resolved InetSocketAddress instances on next(), but it's up to the HostProvider, when it wants to do the resolving. Different HostProvider could be imagined: * A HostProvider that loads the list of Hosts from an URL or from DNS * A HostProvider that re-resolves the InetSocketAddress after a timeout. * A HostProvider that prefers nearby hosts.

Method Summary

Modifier and Type	Method and Description
java.net.InetSocketAddress	next(long spinDelay) The next host to try to connect to.
void	onConnected() Notify the HostProvider of a successful connection.
int	size()
boolean	updateServerList(java.util.Collection<java.net.InetSocketAddress> serverAddresses, java.net.InetSocketAddress currentHost) Update the list of servers.

Method Detail

size

int size()

next

java.net.InetSocketAddress next(long spinDelay)

The next host to try to connect to. For a spinDelay of 0 there should be no wait.

Parameters:

spinDelay - Milliseconds to wait if all hosts have been tried once.

onConnected

void onConnected()

Notify the HostProvider of a successful connection. The HostProvider may use this notification to reset it's inner state.

updateServerList

boolean updateServerList(java.util.Collection<java.net.InetSocketAddress> serverAddresses,
                         java.net.InetSocketAddress currentHost)

Update the list of servers. This returns true if changing connections is necessary for load-balancing, false otherwise.

Parameters:

serverAddresses - new host list

currentHost - the host to which this client is currently connected

Returns:

true if changing connections is necessary for load-balancing, false otherwise