de.zib.scalaris

Class ConnectionPolicy

java.lang.Object

de.zib.scalaris.ConnectionPolicy

Direct Known Subclasses:

DefaultConnectionPolicy, FixedNodeConnectionPolicy

public abstract class ConnectionPolicy
extends Object

Defines a policy on how to select a node to connect to from a set of possible nodes and whether to automatically re-connect.

Since:

2.3

Version:

2.3

Author:

Nico Kruber, kruber@zib.de

See Also:

ConnectionFactory

Constructor Summary

Constructors

Constructor and Description
ConnectionPolicy(List<PeerNode> availableRemoteNodes) Creates a connection policy with the given set of nodes available for connections.
ConnectionPolicy(PeerNode remoteNode) Creates a connection policy with one available node to connect to.

Method Summary

Methods

Modifier and Type	Method and Description
void	availableNodeAdded(PeerNode newNode) Signals the connection policy that the given node has been added to the list of available nodes.
void	availableNodeRemoved(PeerNode removedNode) Signals the connection policy that the given node has been removed from the list of available nodes.
void	availableNodesReset() Signals the connection policy that the list of available nodes has been reset (cleared).
void	nodeConnectSuccess(PeerNode node) Acts upon a successful connect attempt of the given node.
void	nodeFailed(PeerNode node) Acts upon a failure of the given node.
void	nodeFailReset(PeerNode node) Acts upon a failure reset of the given node.
PeerNode	selectNode() Selects the node to connect with when establishing a connection (no failed node, no exception that has already been thrown).
abstract <E extends Exception> PeerNode	selectNode(int retry, PeerNode failedNode, E e) Selects the node to (re-)connect with.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConnectionPolicy

public ConnectionPolicy(PeerNode remoteNode)

Creates a connection policy with one available node to connect to. Provided for convenience.

Parameters:

remoteNode - the node available for connections

ConnectionPolicy

public ConnectionPolicy(List<PeerNode> availableRemoteNodes)

Creates a connection policy with the given set of nodes available for connections.

Parameters:

availableRemoteNodes - available nodes to connect to

Method Detail

availableNodeAdded

public void availableNodeAdded(PeerNode newNode)

Signals the connection policy that the given node has been added to the list of available nodes.

Parameters:

newNode - the new node

availableNodeRemoved

public void availableNodeRemoved(PeerNode removedNode)

Signals the connection policy that the given node has been removed from the list of available nodes.

Parameters:

removedNode - the removed node

availableNodesReset

public void availableNodesReset()

Signals the connection policy that the list of available nodes has been reset (cleared).

nodeFailed

public void nodeFailed(PeerNode node)

Acts upon a failure of the given node. Sets the node's last failed connect time stamp.

Parameters:

node - the failed node

nodeFailReset

public void nodeFailReset(PeerNode node)

Acts upon a failure reset of the given node. Resets the node's last failure state.

Parameters:

node - the node

nodeConnectSuccess

public void nodeConnectSuccess(PeerNode node)

Acts upon a successful connect attempt of the given node. Sets the node's last successful connect time stamp and resets its failure statistics.

Parameters:

node - the node

selectNode

public PeerNode selectNode()
                    throws UnsupportedOperationException

Selects the node to connect with when establishing a connection (no failed node, no exception that has already been thrown). Provided for convenience.

Returns:

the node to use for the connection

Throws:

UnsupportedOperationException - is thrown if the operation can not be performed, e.g. the list is empty

See Also:

ConnectionFactory

selectNode

public abstract <E extends Exception> PeerNode selectNode(int retry,
                                        PeerNode failedNode,
                                        E e)
                             throws E extends Exception,
                                    UnsupportedOperationException

Selects the node to (re-)connect with. If no re-connection is desired, throw an exception!

Type Parameters:

E - the type of the exception that came from the failed connection and may be re-thrown

Parameters:

retry - the n'th retry (initial connect = 0, 1st reconnect = 1,...)

failedNode - the node from the previous connection attempt or null

e - the exception that came back from the previous connection attempt or null

Returns:

the new node to connect with

Throws:

E - if thrown, automatic re-connection attempts will stop

UnsupportedOperationException - is thrown if the operation can not be performed, e.g. the list is empty

E extends Exception

See Also:

Connection.connect(), Connection.doRPC(String, String, com.ericsson.otp.erlang.OtpErlangList), Connection.doRPC(String, String, com.ericsson.otp.erlang.OtpErlangObject[])