Class NodeConnectionsService

  • All Implemented Interfaces:, java.lang.AutoCloseable, LifecycleComponent, Releasable

    public class NodeConnectionsService
    extends AbstractLifecycleComponent
    This component is responsible for maintaining connections from this node to all the nodes listed in the cluster state, and for disconnecting from nodes once they are removed from the cluster state. It periodically checks that all connections are still open and restores them if needed. Note that this component is *not* responsible for removing nodes from the cluster state if they disconnect or are unresponsive: this is the job of the master's fault detection components, particularly FollowersChecker.

    The connectToNodes(DiscoveryNodes, Runnable) and disconnectFromNodesExcept(DiscoveryNodes) methods are called on the ClusterApplier thread. This component allows the ClusterApplier to block on forming connections to _new_ nodes, because the rest of the system treats a missing connection with another node in the cluster state as an exceptional condition and we don't want this to happen to new nodes. However we need not block on re-establishing existing connections because if a connection is down then we are already in an exceptional situation and it doesn't matter much if we stay in this situation a little longer.

    This component does not block on disconnections at all, because a disconnection might need to wait for an ongoing (background) connection attempt to complete first.

    • Field Detail


        public static final Setting<TimeValue> CLUSTER_NODE_RECONNECT_INTERVAL_SETTING
    • Method Detail

      • connectToNodes

        public void connectToNodes​(DiscoveryNodes discoveryNodes,
                                   java.lang.Runnable onCompletion)
        Connect to all the given nodes, but do not disconnect from any extra nodes. Calls the completion handler on completion of all connection attempts to _new_ nodes, but not on attempts to re-establish connections to nodes that are already known.
      • disconnectFromNodesExcept

        public void disconnectFromNodesExcept​(DiscoveryNodes discoveryNodes)
        Disconnect from any nodes to which we are currently connected which do not appear in the given nodes. Does not wait for the disconnections to complete, because they might have to wait for ongoing connection attempts first.
      • reconnectToNodes

        public void reconnectToNodes​(DiscoveryNodes discoveryNodes,
                                     java.lang.Runnable onCompletion)