Package org.apache.pekko.cluster.sharding

Class ShardCoordinator.AbstractShardAllocationStrategy

java.lang.Object

org.apache.pekko.cluster.sharding.ShardCoordinator.AbstractShardAllocationStrategy

All Implemented Interfaces:

NoSerializationVerificationNeeded, ShardCoordinator.ShardAllocationStrategy

Enclosing class:

ShardCoordinator

public abstract static class ShardCoordinator.AbstractShardAllocationStrategy
extends java.lang.Object
implements ShardCoordinator.ShardAllocationStrategy

Java API: Java implementations of custom shard allocation and rebalancing logic used by the ShardCoordinator should extend this abstract class and implement the two methods.

Constructor Summary

Constructors

Constructor	Description
AbstractShardAllocationStrategy()

Method Summary

Modifier and Type	Method	Description
abstract scala.concurrent.Future<ActorRef>	allocateShard(ActorRef requester, java.lang.String shardId, java.util.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations)	Invoked when the location of a new shard is to be decided.
scala.concurrent.Future<ActorRef>	allocateShard(ActorRef requester, java.lang.String shardId, scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations)	Invoked when the location of a new shard is to be decided.
abstract scala.concurrent.Future<java.util.Set<java.lang.String>>	rebalance(java.util.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations, java.util.Set<java.lang.String> rebalanceInProgress)	Invoked periodically to decide which shards to rebalance to another location.
scala.concurrent.Future<scala.collection.immutable.Set<java.lang.String>>	rebalance(scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations, scala.collection.immutable.Set<java.lang.String> rebalanceInProgress)	Invoked periodically to decide which shards to rebalance to another location.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractShardAllocationStrategy

public AbstractShardAllocationStrategy()

Method Detail

allocateShard

public final scala.concurrent.Future<ActorRef> allocateShard(ActorRef requester,
                                                             java.lang.String shardId,
                                                             scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations)

Description copied from interface: ShardCoordinator.ShardAllocationStrategy

Invoked when the location of a new shard is to be decided.

Specified by:

allocateShard in interface ShardCoordinator.ShardAllocationStrategy

Parameters:

requester - actor reference to the ShardRegion that requested the location of the shard, can be returned if preference should be given to the node where the shard was first accessed

shardId - the id of the shard to allocate

currentShardAllocations - all actor refs to ShardRegion and their current allocated shards, in the order they were allocated

Returns:

a Future of the actor ref of the ShardRegion that is to be responsible for the shard, must be one of the references included in the currentShardAllocations parameter

allocateShard

public abstract scala.concurrent.Future<ActorRef> allocateShard(ActorRef requester,
                                                                java.lang.String shardId,
                                                                java.util.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations)

Invoked when the location of a new shard is to be decided.

Parameters:

requester - actor reference to the ShardRegion that requested the location of the shard, can be returned if preference should be given to the node where the shard was first accessed

shardId - the id of the shard to allocate

currentShardAllocations - all actor refs to ShardRegion and their current allocated shards, in the order they were allocated

Returns:

a Future of the actor ref of the ShardRegion that is to be responsible for the shard, must be one of the references included in the currentShardAllocations parameter

rebalance

public final scala.concurrent.Future<scala.collection.immutable.Set<java.lang.String>> rebalance(scala.collection.immutable.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations,
                                                                                                 scala.collection.immutable.Set<java.lang.String> rebalanceInProgress)

Description copied from interface: ShardCoordinator.ShardAllocationStrategy

Invoked periodically to decide which shards to rebalance to another location.

Specified by:

rebalance in interface ShardCoordinator.ShardAllocationStrategy

Parameters:

currentShardAllocations - all actor refs to ShardRegion and their current allocated shards, in the order they were allocated

rebalanceInProgress - set of shards that are currently being rebalanced, i.e. you should not include these in the returned set

Returns:

a Future of the shards to be migrated, may be empty to skip rebalance in this round

rebalance

public abstract scala.concurrent.Future<java.util.Set<java.lang.String>> rebalance(java.util.Map<ActorRef,scala.collection.immutable.IndexedSeq<java.lang.String>> currentShardAllocations,
                                                                                   java.util.Set<java.lang.String> rebalanceInProgress)

Invoked periodically to decide which shards to rebalance to another location.

Parameters:

currentShardAllocations - all actor refs to ShardRegion and their current allocated shards, in the order they were allocated

rebalanceInProgress - set of shards that are currently being rebalanced, i.e. you should not include these in the returned set

Returns:

a Future of the shards to be migrated, may be empty to skip rebalance in this round