org.apache.solr.cloud

Class ZkShardTerms

java.lang.Object

org.apache.solr.cloud.ZkShardTerms

All Implemented Interfaces:

AutoCloseable

public class ZkShardTerms
extends Object
implements AutoCloseable

Class used for interact with a ZK term node. Each ZK term node relates to a shard of a collection and have this format (in json)

{ "replicaNodeName1" : 1, "replicaNodeName2" : 2, .. }

The values correspond to replicas are called terms. Only replicas with highest term value are considered up to date and be able to become leader and serve queries.

Terms can only updated in two strict ways:

• A replica sets its term equals to leader's term
• The leader increase its term and some other replicas by 1

This class should not be reused after Watcher.Event.KeeperState.Expired event

Constructor Summary

Constructors

Constructor and Description
ZkShardTerms(String collection, String shard, SolrZkClient zkClient)

Method Summary

Modifier and Type	Method and Description
boolean	canBecomeLeader(String coreNodeName) Can this replica become leader?
void	close()
void	doneRecovering(String coreNodeName) Mark coreNodeName as finished recovering
void	ensureHighestTermsAreNotZero() When first updates come in, all replicas have some data now, so we must switch from term 0 (registered) to 1 (have some data)
void	ensureTermsIsHigher(String leader, Set<String> replicasNeedingRecovery) Ensure that terms are higher than some replica's terms.
long	getHighestTerm()
ShardTerms	getShardTerms()
long	getTerm(String coreNodeName)
boolean	isRecovering(String name)
void	refreshTerms() Fetch latest terms from ZK
boolean	registered(String coreNodeName) Did this replica registered its term? This is a sign to check f
void	setTermEqualsToLeader(String coreNodeName) Set a replica's term equals to leader's term, and remove recovering flag of a replica.
void	setTermToZero(String coreNodeName) Set a replica's term to 0.
boolean	skipSendingUpdatesTo(String coreNodeName) Should leader skip sending updates to this replica?
void	startRecovering(String coreNodeName) Mark coreNodeName as recovering

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ZkShardTerms

public ZkShardTerms(String collection,
                    String shard,
                    SolrZkClient zkClient)

Method Detail

ensureTermsIsHigher

public void ensureTermsIsHigher(String leader,
                                Set<String> replicasNeedingRecovery)

Ensure that terms are higher than some replica's terms. If the current leader is attempting to give up leadership and included in replicasNeedingRecovery, then other replicas that are in sync will have higher terms, while the leader will stay where it is.

Parameters:

leader - coreNodeName of leader

replicasNeedingRecovery - set of replicas in which their terms should be lower than leader's term

getShardTerms

public ShardTerms getShardTerms()

canBecomeLeader

public boolean canBecomeLeader(String coreNodeName)

Can this replica become leader?

Parameters:

coreNodeName - of the replica

Returns:

true if this replica can become leader, false if otherwise

skipSendingUpdatesTo

public boolean skipSendingUpdatesTo(String coreNodeName)

Should leader skip sending updates to this replica?

Parameters:

coreNodeName - of the replica

Returns:

true if this replica has term equals to leader's term, false if otherwise

registered

public boolean registered(String coreNodeName)

Did this replica registered its term? This is a sign to check f

Parameters:

coreNodeName - of the replica

Returns:

true if this replica registered its term, false if otherwise

close

public void close()

Specified by:

close in interface AutoCloseable

setTermEqualsToLeader

public void setTermEqualsToLeader(String coreNodeName)

Set a replica's term equals to leader's term, and remove recovering flag of a replica. This call should only be used by CollectionParams.CollectionAction.FORCELEADER

Parameters:

coreNodeName - of the replica

setTermToZero

public void setTermToZero(String coreNodeName)

Set a replica's term to 0. If the term does not exist, create it.

Parameters:

coreNodeName - of the replica

startRecovering

public void startRecovering(String coreNodeName)

Mark coreNodeName as recovering

doneRecovering

public void doneRecovering(String coreNodeName)

Mark coreNodeName as finished recovering

isRecovering

public boolean isRecovering(String name)

ensureHighestTermsAreNotZero

public void ensureHighestTermsAreNotZero()

When first updates come in, all replicas have some data now, so we must switch from term 0 (registered) to 1 (have some data)

getHighestTerm

public long getHighestTerm()

getTerm

public long getTerm(String coreNodeName)

refreshTerms

public void refreshTerms()

Fetch latest terms from ZK