org.elasticsearch.cluster.routing.allocation.allocator

Interface ShardsAllocator

All Known Implementing Classes:

BalancedShardsAllocator, ShardsAllocators

public interface ShardsAllocator

A ShardsAllocator is the main entry point for shard allocation on nodes in the cluster. The allocator makes basic decision where a shard instance will be allocated, if already allocated instances need relocate to other nodes due to node failures or due to rebalancing decisions.

Method Summary

Modifier and Type	Method and Description
boolean	allocateUnassigned(RoutingAllocation allocation) Assign all unassigned shards to nodes
void	applyFailedShards(FailedRerouteAllocation allocation) Applies changes on failed nodes based on the implemented algorithm.
void	applyStartedShards(StartedRerouteAllocation allocation) Applies changes on started nodes based on the implemented algorithm.
boolean	moveShards(RoutingAllocation allocation) Move started shards that can not be allocated to a node anymore
boolean	rebalance(RoutingAllocation allocation) Rebalancing number of shards on all nodes

Method Detail

applyStartedShards

void applyStartedShards(StartedRerouteAllocation allocation)

Applies changes on started nodes based on the implemented algorithm. For example if a shard has changed to ShardRoutingState.STARTED from ShardRoutingState.RELOCATING this allocator might apply some cleanups on the node that used to hold the shard.

Parameters:

allocation - all started shards

applyFailedShards

void applyFailedShards(FailedRerouteAllocation allocation)

Applies changes on failed nodes based on the implemented algorithm.

Parameters:

allocation - all failed shards

allocateUnassigned

boolean allocateUnassigned(RoutingAllocation allocation)

Assign all unassigned shards to nodes

Parameters:

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false

rebalance

boolean rebalance(RoutingAllocation allocation)

Rebalancing number of shards on all nodes

Parameters:

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false

moveShards

boolean moveShards(RoutingAllocation allocation)

Move started shards that can not be allocated to a node anymore

Parameters:

allocation - current node allocation

Returns:

true if the allocation has changed, otherwise false