Interface IShardAllocationStrategy

Interface of the pluggable shard allocation and rebalancing logic used by the Akka.Cluster.Sharding.PersistentShardCoordinator.

Namespace: Akka.Cluster.Sharding
Assembly: Akka.Cluster.Sharding.dll
Syntax
public interface IShardAllocationStrategy : INoSerializationVerificationNeeded

Methods

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AllocateShard(IActorRef, String, IImmutableDictionary<IActorRef, IImmutableList<String>>)

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

Declaration
Task<IActorRef> AllocateShard(IActorRef requester, string shardId, IImmutableDictionary<IActorRef, IImmutableList<string>> currentShardAllocations)
Parameters
Type Name Description
IActorRef 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.
String shardId

The id of the shard to allocate.
System.Collections.Immutable.IImmutableDictionary<IActorRef, System.Collections.Immutable.IImmutableList<String>> currentShardAllocations

All actor refs to ShardRegion and their current allocated shards, in the order they were allocated
Returns
Type Description
Task<IActorRef>

Task 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.
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Rebalance(IImmutableDictionary<IActorRef, IImmutableList<String>>, IImmutableSet<String>)

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

Declaration
Task<IImmutableSet<string>> Rebalance(IImmutableDictionary<IActorRef, IImmutableList<string>> currentShardAllocations, IImmutableSet<string> rebalanceInProgress)
Parameters
Type Name Description
System.Collections.Immutable.IImmutableDictionary<IActorRef, System.Collections.Immutable.IImmutableList<String>> currentShardAllocations

All actor refs to ShardRegion and their current allocated shards, in the order they were allocated.
System.Collections.Immutable.IImmutableSet<String> rebalanceInProgress

Set of shards that are currently being rebalanced, i.e. you should not include these in the returned set.
Returns
Type Description
Task<System.Collections.Immutable.IImmutableSet<String>>

Task of the shards to be migrated, may be empty to skip rebalance in this round.

Extension Methods