org.apache.druid.server.coordinator

Class RandomBalancerStrategy

java.lang.Object

org.apache.druid.server.coordinator.RandomBalancerStrategy

All Implemented Interfaces:

BalancerStrategy

public class RandomBalancerStrategy
extends Object
implements BalancerStrategy

Constructor Summary

Constructors

Constructor and Description
RandomBalancerStrategy()

Method Summary

Modifier and Type	Method and Description
void	emitStats(String tier, CoordinatorStats stats, List<ServerHolder> serverHolderList) Add balancing strategy stats during the 'balanceTier' operation of DruidCoordinatorBalancer to be included
ServerHolder	findNewSegmentHomeBalancer(org.apache.druid.timeline.DataSegment proposalSegment, List<ServerHolder> serverHolders) Find the best server to move a DataSegment to according the the balancing strategy.
ServerHolder	findNewSegmentHomeReplicator(org.apache.druid.timeline.DataSegment proposalSegment, List<ServerHolder> serverHolders) Find the best server on which to place a DataSegment replica according to the balancing strategy
BalancerSegmentHolder	pickSegmentToMove(List<ServerHolder> serverHolders) Pick the best segment to move from one of the supplied set of servers according to the balancing strategy.
Iterator<ServerHolder>	pickServersToDrop(org.apache.druid.timeline.DataSegment toDropSegment, NavigableSet<ServerHolder> serverHolders) Returns an iterator for a set of servers to drop from, ordered by preference of which server to drop from first for a given drop strategy.

Methods inherited from class java.lang.Object

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

Constructor Detail

RandomBalancerStrategy

public RandomBalancerStrategy()

Method Detail

findNewSegmentHomeReplicator

public ServerHolder findNewSegmentHomeReplicator(org.apache.druid.timeline.DataSegment proposalSegment,
                                                 List<ServerHolder> serverHolders)

Description copied from interface: BalancerStrategy

Find the best server on which to place a DataSegment replica according to the balancing strategy

Specified by:

findNewSegmentHomeReplicator in interface BalancerStrategy

Parameters:

proposalSegment - segment to replicate

serverHolders - servers to consider as replica holders

Returns:

The server to replicate to, or null if no suitable server is found

findNewSegmentHomeBalancer

public ServerHolder findNewSegmentHomeBalancer(org.apache.druid.timeline.DataSegment proposalSegment,
                                               List<ServerHolder> serverHolders)

Description copied from interface: BalancerStrategy

Find the best server to move a DataSegment to according the the balancing strategy.

Specified by:

findNewSegmentHomeBalancer in interface BalancerStrategy

Parameters:

proposalSegment - segment to move

serverHolders - servers to consider as move destinations

Returns:

The server to move to, or null if no move should be made or no server is suitable

pickSegmentToMove

public BalancerSegmentHolder pickSegmentToMove(List<ServerHolder> serverHolders)

Description copied from interface: BalancerStrategy

Pick the best segment to move from one of the supplied set of servers according to the balancing strategy.

Specified by:

pickSegmentToMove in interface BalancerStrategy

Parameters:

serverHolders - set of historicals to consider for moving segments

Returns:

BalancerSegmentHolder containing segment to move and server it current resides on

pickServersToDrop

public Iterator<ServerHolder> pickServersToDrop(org.apache.druid.timeline.DataSegment toDropSegment,
                                                NavigableSet<ServerHolder> serverHolders)

Description copied from interface: BalancerStrategy

Returns an iterator for a set of servers to drop from, ordered by preference of which server to drop from first for a given drop strategy. One or more segments may be dropped, depending on how much the segment is over-replicated.

Specified by:

pickServersToDrop in interface BalancerStrategy

Parameters:

toDropSegment - segment to drop from one or more servers

serverHolders - set of historicals to consider dropping from

Returns:

Iterator for set of historicals, ordered by drop preference

emitStats

public void emitStats(String tier,
                      CoordinatorStats stats,
                      List<ServerHolder> serverHolderList)

Description copied from interface: BalancerStrategy

Add balancing strategy stats during the 'balanceTier' operation of DruidCoordinatorBalancer to be included

Specified by:

emitStats in interface BalancerStrategy

Parameters:

tier - historical tier being balanced

stats - stats object to add balancing strategy stats to

serverHolderList - servers in tier being balanced