Class ExternalShardAllocationStrategy

Inheritance
object
ExternalShardAllocationStrategy
Implements
Inherited Members
Namespace: Akka.Cluster.Sharding.External
Assembly: Akka.Cluster.Sharding.dll
Syntax
public class ExternalShardAllocationStrategy : IStartableAllocationStrategy, IShardAllocationStrategy, INoSerializationVerificationNeeded

Constructors

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ExternalShardAllocationStrategy(ActorSystem, string)

Declaration
public ExternalShardAllocationStrategy(ActorSystem system, string typeName)
Parameters
Type Name Description
ActorSystem system
string typeName

Properties

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Timeout

Declaration
protected virtual TimeSpan Timeout { get; }
Property Value
Type Description
TimeSpan

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
public 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.
IImmutableDictionary<IActorRef, 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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CreateShardStateActor()

Declaration
protected virtual IActorRef CreateShardStateActor()
Returns
Type Description
IActorRef
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Rebalance(IImmutableDictionary<IActorRef, IImmutableList<string>>, IImmutableSet<string>)

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

Declaration
public Task<IImmutableSet<string>> Rebalance(IImmutableDictionary<IActorRef, IImmutableList<string>> currentShardAllocations, IImmutableSet<string> rebalanceInProgress)
Parameters
Type Name Description
IImmutableDictionary<IActorRef, IImmutableList<string>> currentShardAllocations

All actor refs to ShardRegion and their current allocated shards, in the order they were allocated.
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<IImmutableSet<string>>

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

Called before any calls to allocate/rebalance. Do not block. If asynchronous actions are required they can be started here and delay the Futures returned by allocate/rebalance.

Declaration
public void Start()

Implements

Extension Methods