org.apache.zookeeper.server.quorum.flexible

Class QuorumHierarchical

java.lang.Object

org.apache.zookeeper.server.quorum.flexible.QuorumHierarchical

All Implemented Interfaces:

QuorumVerifier

public class QuorumHierarchical
extends Object
implements QuorumVerifier

This class implements a validator for hierarchical quorums. With this construction, zookeeper servers are split into disjoint groups, and each server has a weight. We obtain a quorum if we get more than half of the total weight of a group for a majority of groups. The configuration of quorums uses two parameters: group and weight. Groups are sets of ZooKeeper servers, and we set a group by passing a colon-separated list of server ids. It is also necessary to assign weights to server. Here is an example of a configuration that creates three groups and assigns a weight of 1 to each server: group.1=1:2:3 group.2=4:5:6 group.3=7:8:9 weight.1=1 weight.2=1 weight.3=1 weight.4=1 weight.5=1 weight.6=1 weight.7=1 weight.8=1 weight.9=1 Note that it is still necessary to define peers using the server keyword.

Constructor Summary

Constructors

Constructor and Description
QuorumHierarchical(Properties qp) This constructor takes a set of properties.
QuorumHierarchical(String filename) This contructor requires the quorum configuration to be declared in a separate file, and it takes the file as an input parameter.

Method Summary

Modifier and Type	Method and Description
boolean	containsQuorum(Set<Long> set) Verifies if a given set is a quorum.
boolean	equals(Object o)
Map<Long,QuorumPeer.QuorumServer>	getAllMembers()
Map<Long,QuorumPeer.QuorumServer>	getObservingMembers()
long	getVersion()
Map<Long,QuorumPeer.QuorumServer>	getVotingMembers()
long	getWeight(long id) Returns the weight of a server.
int	hashCode()
void	setVersion(long ver)
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

QuorumHierarchical

public QuorumHierarchical(String filename)
                   throws QuorumPeerConfig.ConfigException

This contructor requires the quorum configuration to be declared in a separate file, and it takes the file as an input parameter.

Throws:

QuorumPeerConfig.ConfigException

QuorumHierarchical

public QuorumHierarchical(Properties qp)
                   throws QuorumPeerConfig.ConfigException

This constructor takes a set of properties. We use it in the unit test for this feature.

Throws:

QuorumPeerConfig.ConfigException

Method Detail

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Specified by:

equals in interface QuorumVerifier

Overrides:

equals in class Object

getWeight

public long getWeight(long id)

Returns the weight of a server.

Specified by:

getWeight in interface QuorumVerifier

Parameters:

id -

getAllMembers

public Map<Long,QuorumPeer.QuorumServer> getAllMembers()

Specified by:

getAllMembers in interface QuorumVerifier

toString

public String toString()

Specified by:

toString in interface QuorumVerifier

Overrides:

toString in class Object

containsQuorum

public boolean containsQuorum(Set<Long> set)

Verifies if a given set is a quorum.

Specified by:

containsQuorum in interface QuorumVerifier

getVotingMembers

public Map<Long,QuorumPeer.QuorumServer> getVotingMembers()

Specified by:

getVotingMembers in interface QuorumVerifier

getObservingMembers

public Map<Long,QuorumPeer.QuorumServer> getObservingMembers()

Specified by:

getObservingMembers in interface QuorumVerifier

getVersion

public long getVersion()

Specified by:

getVersion in interface QuorumVerifier

setVersion

public void setVersion(long ver)

Specified by:

setVersion in interface QuorumVerifier