Module org.elasticsearch.server
Package org.elasticsearch.cluster.routing.allocation

Class MoveDecision

java.lang.Object
org.elasticsearch.cluster.routing.allocation.AbstractAllocationDecision
org.elasticsearch.cluster.routing.allocation.MoveDecision
All Implemented Interfaces:
Writeable, ChunkedToXContent, ChunkedToXContentObject
public final class MoveDecision extends AbstractAllocationDecision
Represents a decision to move a started shard, either because it is no longer allowed to remain on its current node or because moving it to another node will form a better cluster balance.

  • Field Details

    • NOT_TAKEN

      public static final MoveDecision NOT_TAKEN
      a constant representing no decision taken

  • Constructor Details

  • Method Details

    • writeTo

      public void writeTo(StreamOutput out) throws IOException
      Description copied from interface: Writeable
      Write this into the StreamOutput.
      Specified by:
      writeTo in interface Writeable
      Overrides:
      writeTo in class AbstractAllocationDecision
      Throws:
      IOException

    • remain

      public static MoveDecision remain(Decision canRemainDecision)
      Creates a move decision for the shard being able to remain on its current node, so the shard won't be forced to move to another node.

    • move

      public static MoveDecision move(Decision canRemainDecision, AllocationDecision moveDecision, @Nullable DiscoveryNode targetNode, @Nullable List<NodeAllocationResult> nodeDecisions)
      Creates a move decision for the shard.
      Parameters:
      canRemainDecision - the decision for whether the shard is allowed to remain on its current node
      moveDecision - the AllocationDecision for moving the shard to another node
      targetNode - the node where the shard should move to
      nodeDecisions - the node-level decisions that comprised the final decision, non-null iff explain is true
      Returns:
      the MoveDecision for moving the shard to another node

    • rebalance

      public static MoveDecision rebalance(Decision canRemainDecision, Decision canRebalanceDecision, AllocationDecision canMoveDecision, @Nullable DiscoveryNode targetNode, int currentNodeRanking, List<NodeAllocationResult> nodeDecisions)
      Creates a decision for whether to move the shard to a different node to form a better cluster balance.

    • isDecisionTaken

      public boolean isDecisionTaken()
      Description copied from class: AbstractAllocationDecision
      Returns true if a decision was taken by the allocator, false otherwise. If no decision was taken, then the rest of the fields in this object cannot be accessed and will throw an IllegalStateException.
      Specified by:
      isDecisionTaken in class AbstractAllocationDecision

    • forceMove

      public boolean forceMove()
      Returns true if the shard cannot remain on its current node and can be moved, returns false otherwise. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • canRemain

      public boolean canRemain()
      Returns true if the shard can remain on its current node, returns false otherwise. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • getCanRemainDecision

      public Decision getCanRemainDecision()
      Returns the decision for the shard being allowed to remain on its current node. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • canRebalanceCluster

      public boolean canRebalanceCluster()
      Returns true if the shard is allowed to be rebalanced to another node in the cluster, returns false otherwise. If getClusterRebalanceDecision() returns null, then the result of this method is meaningless, as no rebalance decision was taken. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • getClusterRebalanceDecision

      @Nullable public Decision getClusterRebalanceDecision()
      Returns the decision for being allowed to rebalance the shard. Invoking this method will return null if canRemain() ()} returns false, which means the node is not allowed to remain on its current node, so the cluster is forced to attempt to move the shard to a different node, as opposed to attempting to rebalance the shard if a better cluster balance is possible by moving it. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • getAllocationDecision

      @Nullable public AllocationDecision getAllocationDecision()
      Returns the AllocationDecision for moving this shard to another node. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • getCurrentNodeRanking

      public int getCurrentNodeRanking()
      Gets the current ranking of the node to which the shard is currently assigned, relative to the other nodes in the cluster as reported in NodeAllocationResult.getWeightRanking(). The ranking will only return a meaningful positive integer if getClusterRebalanceDecision() returns a non-null value; otherwise, 0 will be returned. If isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.

    • getExplanation

      public String getExplanation()
      Description copied from class: AbstractAllocationDecision
      Gets the explanation for the decision. If AbstractAllocationDecision.isDecisionTaken() returns false, then invoking this method will throw an IllegalStateException.
      Specified by:
      getExplanation in class AbstractAllocationDecision

    • toXContentChunked

      public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params params)
      Description copied from interface: ChunkedToXContent
      Create an iterator of ToXContent chunks for a REST response. Each chunk is serialized with the same XContentBuilder and ToXContent.Params, which is also the same as the ToXContent.Params passed as the params argument. For best results, all chunks should be O(1) size. The last chunk in the iterator must always yield at least one byte of output. See also ChunkedToXContentHelper for some handy utilities.

      Note that chunked response bodies cannot send deprecation warning headers once transmission has started, so implementations must check for deprecated feature use before returning.

      Returns:
      iterator over chunks of ToXContent

    • equals

      public boolean equals(Object other)
      Overrides:
      equals in class AbstractAllocationDecision

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class AbstractAllocationDecision