Package io.grpc.xds

Class RingHashLoadBalancer

  • final class RingHashLoadBalancer
extends io.grpc.util.MultiChildLoadBalancer
    A LoadBalancer that provides consistent hashing based load balancing to upstream hosts. It implements the "Ketama" hashing that maps hosts onto a circle (the "ring") by hashing its addresses. Each request is routed to a host by hashing some property of the request and finding the nearest corresponding host clockwise around the ring. Each host is placed on the ring some number of times proportional to its weight. With the ring partitioned appropriately, the addition or removal of one host from a set of N hosts will affect only 1/N requests.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      private static class  RingHashLoadBalancer.RingEntry  
      (package private) static class  RingHashLoadBalancer.RingHashConfig
      Configures the ring property.
      private static class  RingHashLoadBalancer.RingHashPicker  
      private static class  RingHashLoadBalancer.SubchannelView
      An unmodifiable view of a subchannel with state not subject to its real connectivity state changes.

      • Nested classes/interfaces inherited from class io.grpc.util.MultiChildLoadBalancer

        io.grpc.util.MultiChildLoadBalancer.AcceptResolvedAddrRetVal, io.grpc.util.MultiChildLoadBalancer.ChildLbState, io.grpc.util.MultiChildLoadBalancer.Endpoint

      • Nested classes/interfaces inherited from class io.grpc.LoadBalancer

        io.grpc.LoadBalancer.CreateSubchannelArgs, io.grpc.LoadBalancer.ErrorPicker, io.grpc.LoadBalancer.Factory, io.grpc.LoadBalancer.FixedResultPicker, io.grpc.LoadBalancer.Helper, io.grpc.LoadBalancer.PickDetailsConsumer, io.grpc.LoadBalancer.PickResult, io.grpc.LoadBalancer.PickSubchannelArgs, io.grpc.LoadBalancer.ResolvedAddresses, io.grpc.LoadBalancer.Subchannel, io.grpc.LoadBalancer.SubchannelPicker, io.grpc.LoadBalancer.SubchannelStateListener

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static XxHash64 hashFunc  
      private io.grpc.LoadBalancer.Factory lazyLbFactory  
      private XdsLogger logger  
      private java.util.List<RingHashLoadBalancer.RingEntry> ring  
      private static io.grpc.Status RPC_HASH_NOT_FOUND  
      private io.grpc.SynchronizationContext syncContext  

      • Fields inherited from class io.grpc.util.MultiChildLoadBalancer

        currentConnectivityState, pickFirstLbProvider, resolvingAddresses

      • Fields inherited from class io.grpc.LoadBalancer

        ATTR_HEALTH_CHECKING_CONFIG, DISABLE_SUBCHANNEL_RECONNECT_KEY, EMPTY_PICKER, HAS_HEALTH_PRODUCER_LISTENER_KEY, HEALTH_CONSUMER_LISTENER_ARG_KEY, IS_PETIOLE_POLICY

    • Constructor Summary

      Constructors 
      Constructor Description
      RingHashLoadBalancer​(io.grpc.LoadBalancer.Helper helper)  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      io.grpc.Status acceptResolvedAddresses​(io.grpc.LoadBalancer.ResolvedAddresses resolvedAddresses)  
      private static java.util.List<RingHashLoadBalancer.RingEntry> buildRing​(java.util.Map<io.grpc.EquivalentAddressGroup,​java.lang.Long> serverWeights, long totalWeight, double scale)  
      protected io.grpc.util.MultiChildLoadBalancer.ChildLbState createChildLbState​(java.lang.Object key)  
      static io.grpc.EquivalentAddressGroup stripAttrs​(io.grpc.EquivalentAddressGroup eag)  
      protected void updateOverallBalancingState()
      Updates the overall balancing state by aggregating the connectivity states of all subchannels.
      private io.grpc.Status validateAddrList​(java.util.List<io.grpc.EquivalentAddressGroup> addrList)  
      private java.lang.String validateNoDuplicateAddresses​(java.util.List<io.grpc.EquivalentAddressGroup> addrList)  

      • Methods inherited from class io.grpc.util.MultiChildLoadBalancer

        acceptResolvedAddressesInternal, aggregateState, createChildAddressesMap, getChildLbState, getChildLbStateEag, getChildLbStates, getHelper, getReadyChildren, handleNameResolutionError, shutdown, shutdownRemoved

      • Methods inherited from class io.grpc.LoadBalancer

        canHandleEmptyAddressListFromNameResolution, handleResolvedAddresses, handleSubchannelState, requestConnection

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • RPC_HASH_NOT_FOUND

        private static final io.grpc.Status RPC_HASH_NOT_FOUND

      • hashFunc

        private static final XxHash64 hashFunc

      • lazyLbFactory

        private final io.grpc.LoadBalancer.Factory lazyLbFactory

      • syncContext

        private final io.grpc.SynchronizationContext syncContext

    • Constructor Detail

      • RingHashLoadBalancer

        RingHashLoadBalancer​(io.grpc.LoadBalancer.Helper helper)

    • Method Detail

      • acceptResolvedAddresses

        public io.grpc.Status acceptResolvedAddresses​(io.grpc.LoadBalancer.ResolvedAddresses resolvedAddresses)
        Overrides:
        acceptResolvedAddresses in class io.grpc.util.MultiChildLoadBalancer

      • updateOverallBalancingState

        protected void updateOverallBalancingState()
        Updates the overall balancing state by aggregating the connectivity states of all subchannels.

        Aggregation rules (in order of dominance):

        1. If there is at least one subchannel in READY state, overall state is READY
        2. If there are 2 or more subchannels in TRANSIENT_FAILURE, overall state is TRANSIENT_FAILURE (to allow timely failover to another policy)
        3. If there is at least one subchannel in CONNECTING state, overall state is CONNECTING
        4. If there is one subchannel in TRANSIENT_FAILURE state and there is more than one subchannel, report CONNECTING
        5. If there is at least one subchannel in IDLE state, overall state is IDLE
        6. Otherwise, overall state is TRANSIENT_FAILURE
        Specified by:
        updateOverallBalancingState in class io.grpc.util.MultiChildLoadBalancer

      • createChildLbState

        protected io.grpc.util.MultiChildLoadBalancer.ChildLbState createChildLbState​(java.lang.Object key)
        Overrides:
        createChildLbState in class io.grpc.util.MultiChildLoadBalancer

      • validateAddrList

        private io.grpc.Status validateAddrList​(java.util.List<io.grpc.EquivalentAddressGroup> addrList)

      • validateNoDuplicateAddresses

        @Nullable
private java.lang.String validateNoDuplicateAddresses​(java.util.List<io.grpc.EquivalentAddressGroup> addrList)

      • buildRing

        private static java.util.List<RingHashLoadBalancer.RingEntry> buildRing​(java.util.Map<io.grpc.EquivalentAddressGroup,​java.lang.Long> serverWeights,
                                                                        long totalWeight,
                                                                        double scale)

      • stripAttrs

        public static io.grpc.EquivalentAddressGroup stripAttrs​(io.grpc.EquivalentAddressGroup eag)