services.moleculer.strategy

Class ShardStrategy<T extends Endpoint>

java.lang.Object

services.moleculer.strategy.Strategy<T>

services.moleculer.strategy.ArrayBasedStrategy<T>

services.moleculer.strategy.XorShiftRandomStrategy<T>

services.moleculer.strategy.ShardStrategy<T>

public class ShardStrategy<T extends Endpoint>
extends XorShiftRandomStrategy<T>

Sharding invocation strategy. Using consistent-hashing.
More info: https://www.toptal.com/big-data/consistent-hashing

See Also:

RoundRobinStrategy, NanoSecRandomStrategy, XorShiftRandomStrategy, SecureRandomStrategy, CpuUsageStrategy, NetworkLatencyStrategy

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	ShardStrategy.Ring

Field Summary

Fields

Modifier and Type	Field and Description
protected int	cacheSize Size of the memory cache (0 = disabled)
protected java.util.function.Function<java.lang.String,java.lang.Long>	hash Hasher function (generated hash is 32 bits long, default method is MD5)
protected java.util.concurrent.atomic.AtomicReference<ShardStrategy.Ring>	ringRef The "hash ring" (https://www.toptal.com/big-data/consistent-hashing)
protected java.lang.Integer	ringSize Ring size (optional)
protected java.lang.String	shardKey Shard key's path (eg.
protected boolean	useMeta Size of the memory cache (0 = disabled)
protected int	vnodes Number of virtual nodes

Fields inherited from class services.moleculer.strategy.XorShiftRandomStrategy

rnd

Fields inherited from class services.moleculer.strategy.ArrayBasedStrategy

endpointCache, endpoints, nodeID, preferLocal

Constructor Summary

Constructors

Constructor and Description
ShardStrategy(ServiceBroker broker, boolean preferLocal, java.lang.String shardKey, int vnodes, java.lang.Integer ringSize, int cacheSize, java.util.function.Function<java.lang.String,java.lang.Long> hash)

Method Summary

Modifier and Type	Method and Description
void	addEndpoint(T endpoint)
protected java.lang.String	getKeyFromContext(Context ctx)
Endpoint	next(Context ctx, Endpoint[] array)
protected void	rebuild()
boolean	remove(java.lang.String nodeID)

Methods inherited from class services.moleculer.strategy.ArrayBasedStrategy

getAllEndpoints, getEndpoint, getEndpointsByNodeID, isEmpty

Methods inherited from class java.lang.Object

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

Field Detail

shardKey

protected final java.lang.String shardKey

Shard key's path (eg. "userID", "user.email", etc.)

vnodes

protected final int vnodes

Number of virtual nodes

ringSize

protected final java.lang.Integer ringSize

Ring size (optional)

useMeta

protected final boolean useMeta

Size of the memory cache (0 = disabled)

cacheSize

protected final int cacheSize

Size of the memory cache (0 = disabled)

ringRef

protected final java.util.concurrent.atomic.AtomicReference<ShardStrategy.Ring> ringRef

The "hash ring" (https://www.toptal.com/big-data/consistent-hashing)

hash

protected final java.util.function.Function<java.lang.String,java.lang.Long> hash

Hasher function (generated hash is 32 bits long, default method is MD5)

Constructor Detail

ShardStrategy

public ShardStrategy(ServiceBroker broker,
                     boolean preferLocal,
                     java.lang.String shardKey,
                     int vnodes,
                     java.lang.Integer ringSize,
                     int cacheSize,
                     java.util.function.Function<java.lang.String,java.lang.Long> hash)

Method Detail

addEndpoint

public void addEndpoint(T endpoint)

Overrides:

addEndpoint in class ArrayBasedStrategy<T extends Endpoint>

remove

public boolean remove(java.lang.String nodeID)

Overrides:

remove in class ArrayBasedStrategy<T extends Endpoint>

next

public Endpoint next(Context ctx,
                     Endpoint[] array)

Overrides:

next in class XorShiftRandomStrategy<T extends Endpoint>

getKeyFromContext

protected java.lang.String getKeyFromContext(Context ctx)

rebuild

protected void rebuild()