Package org.apache.solr.cluster.placement

Interface PlacementPlugin

All Known Implementing Classes:

RandomPlacementFactory.RandomPlacementPlugin, SimplePlacementFactory.SimplePlacementPlugin

public interface PlacementPlugin

Implemented by external plugins to control replica placement and movement on the search cluster (as well as other things such as cluster elasticity?) when cluster changes are required (initiated elsewhere, most likely following a Collection API call).

Instances of classes implementing this interface are created by PlacementPluginFactory

Implementations of this interface must be reentrant. computePlacement(org.apache.solr.cluster.placement.PlacementRequest, org.apache.solr.cluster.placement.PlacementContext) will be called concurrently from many threads.

Method Summary

Modifier and Type	Method	Description
default PlacementPlan	computePlacement(PlacementRequest placementRequest, PlacementContext placementContext)	Request from plugin code to compute placement.
List<PlacementPlan>	computePlacements(Collection<PlacementRequest> placementRequests, PlacementContext placementContext)	Request from plugin code to compute multiple placements.
default void	verifyAllowedModification(ModificationRequest modificationRequest, PlacementContext placementContext)	Verify that a collection layout modification doesn't violate constraints on replica placements required by this plugin.

Method Detail

computePlacement

default PlacementPlan computePlacement(PlacementRequest placementRequest,
                                       PlacementContext placementContext)
                                throws PlacementException,
                                       InterruptedException

Request from plugin code to compute placement. Note this method must be reentrant as a plugin instance may (read will) get multiple such calls in parallel.

Configuration is passed upon creation of a new instance of this class by PlacementPluginFactory.createPluginInstance().

Parameters:

placementRequest - request for placing new replicas or moving existing replicas on the cluster.

Returns:

plan satisfying the placement request.

Throws:

PlacementException

InterruptedException

computePlacements

List<PlacementPlan> computePlacements(Collection<PlacementRequest> placementRequests,
                                      PlacementContext placementContext)
                               throws PlacementException,
                                      InterruptedException

Request from plugin code to compute multiple placements. If multiple placements are requested, then the PlacementPlan computed for each PlacementRequest will be used to affect the starting state for each subsequent PlacementRequest in the list. This means that each PlacementRequest is computed in the context of the previous PlacementRequest's already having been implemented. Note this method must be reentrant as a plugin instance may (read will) get multiple such calls in parallel.

Configuration is passed upon creation of a new instance of this class by PlacementPluginFactory.createPluginInstance().

Parameters:

placementRequests - requests for placing new replicas or moving existing replicas on the cluster.

Returns:

plan satisfying all placement requests.

Throws:

PlacementException

InterruptedException

verifyAllowedModification

default void verifyAllowedModification(ModificationRequest modificationRequest,
                                       PlacementContext placementContext)
                                throws PlacementModificationException,
                                       InterruptedException

Verify that a collection layout modification doesn't violate constraints on replica placements required by this plugin. Default implementation is a no-op (any modifications are allowed).

Parameters:

modificationRequest - modification request.

placementContext - placement context.

Throws:

PlacementModificationException - if the requested modification would violate replica placement constraints.

InterruptedException