Package org.opensearch.cluster

Class NodeConnectionsService

java.lang.Object

org.opensearch.common.lifecycle.AbstractLifecycleComponent

org.opensearch.cluster.NodeConnectionsService

All Implemented Interfaces:

Closeable, AutoCloseable, org.opensearch.common.lease.Releasable, org.opensearch.common.lifecycle.LifecycleComponent

@PublicApi(since="1.0.0")
public class NodeConnectionsService
extends org.opensearch.common.lifecycle.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 cluster-manager'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.

Opensearch.api:

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	NodeConnectionsService.ConnectionTarget	NodeConnectionsService.ConnectionTarget ensures that we are never concurrently connecting to and disconnecting from a node, and that we eventually either connect to or disconnect from it according to whether NodeConnectionsService.ConnectionTarget.connect(ActionListener) or NodeConnectionsService.ConnectionTarget.disconnect() was called last.

Field Summary

Fields

Modifier and Type	Field	Description
static final Setting<org.opensearch.common.unit.TimeValue>	CLUSTER_NODE_RECONNECT_INTERVAL_SETTING
protected org.opensearch.cluster.NodeConnectionsService.ConnectionChecker	connectionChecker
protected final Map<DiscoveryNode,NodeConnectionsService.ConnectionTarget>	targetsByNode

Fields inherited from class org.opensearch.common.lifecycle.AbstractLifecycleComponent

lifecycle

Constructor Summary

Constructors

Constructor	Description
NodeConnectionsService(Settings settings, ThreadPool threadPool, TransportService transportService)

Method Summary

Modifier and Type	Method	Description
void	clearPendingDisconnections()
protected void	connectDisconnectedTargets(Runnable onCompletion)	Makes a single attempt to reconnect to any nodes which are disconnected but should be connected.
void	connectToNodes(DiscoveryNodes discoveryNodes, Runnable onCompletion)	Connect to all the given nodes, but do not disconnect from any extra nodes.
protected NodeConnectionsService.ConnectionTarget	createConnectionTarget(DiscoveryNode discoveryNode)
void	disconnectFromNodesExcept(DiscoveryNodes discoveryNodes)	Disconnect from any nodes to which we are currently connected which do not appear in the given nodes.
protected void	doClose()
protected void	doStart()
protected void	doStop()
void	reconnectToNodes(DiscoveryNodes discoveryNodes, Runnable onCompletion)
void	setPendingDisconnections(Set<DiscoveryNode> nodes)

Methods inherited from class org.opensearch.common.lifecycle.AbstractLifecycleComponent

addLifecycleListener, close, lifecycleState, removeLifecycleListener, start, stop

Methods inherited from class java.lang.Object

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

Field Details

CLUSTER_NODE_RECONNECT_INTERVAL_SETTING

public static final Setting<org.opensearch.common.unit.TimeValue> CLUSTER_NODE_RECONNECT_INTERVAL_SETTING

targetsByNode

protected final Map<DiscoveryNode,NodeConnectionsService.ConnectionTarget> targetsByNode

connectionChecker

protected volatile org.opensearch.cluster.NodeConnectionsService.ConnectionChecker connectionChecker

Constructor Details

NodeConnectionsService

@Inject
public NodeConnectionsService(Settings settings,
 ThreadPool threadPool,
 TransportService transportService)

Method Details

createConnectionTarget

protected NodeConnectionsService.ConnectionTarget createConnectionTarget(DiscoveryNode discoveryNode)

connectToNodes

public void connectToNodes(DiscoveryNodes discoveryNodes,
 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.

setPendingDisconnections

public void setPendingDisconnections(Set<DiscoveryNode> nodes)

clearPendingDisconnections

public void clearPendingDisconnections()

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.

connectDisconnectedTargets

protected void connectDisconnectedTargets(Runnable onCompletion)

Makes a single attempt to reconnect to any nodes which are disconnected but should be connected. Does not attempt to reconnect any nodes which are in the process of disconnecting. The onCompletion handler is called after all ongoing connection/disconnection attempts have completed.

doStart

protected void doStart()

Specified by:

doStart in class org.opensearch.common.lifecycle.AbstractLifecycleComponent

doStop

protected void doStop()

Specified by:

doStop in class org.opensearch.common.lifecycle.AbstractLifecycleComponent

doClose

protected void doClose()

Specified by:

doClose in class org.opensearch.common.lifecycle.AbstractLifecycleComponent

reconnectToNodes

public void reconnectToNodes(DiscoveryNodes discoveryNodes,
 Runnable onCompletion)