/**
* Creates a new Link or gets an existing one from the the given NodeID.
*
* @param nodeID
* NodeID of the Node to connect to.
* @return A Link connected to the remote Node of given NodeID
* @//throws JCSPNetworkException
* Thrown if there is a problem connecting to the Node
* @//throws ArgumentException
* Thrown if an attempt is made to connect to the local Node
*/
public static Link getLink(NodeID nodeID)
////throws JCSPNetworkException, ArgumentException
{
if (nodeID.equals(Node.getInstance().getNodeID()))
{
throw new ArgumentException("Attempted to connect to the local Node");
}
// Log start of Link creation
Node.log.log(typeof(LinkFactory), "Trying to get link to " + nodeID.toString());
// First check if Link to NodeID exists. Request the Link from the Link Manager
Link toReturn = LinkManager.getInstance().requestLink(nodeID);
if (toReturn != null)
{
// A Link already exists to given NodeID. Log and return existing Link
Node.log.log(typeof(LinkFactory), "Link to " + nodeID.toString()
+ " already exists. Returning existing Link");
return(toReturn);
}
// An existing Link does not exist within the Link Manager. Log, and then create Link via the address
Node.log.log(typeof(LinkFactory), "Link does not exist to " + nodeID.toString() + ". Creating new Link");
toReturn = nodeID.getNodeAddress().createLink();
// Now attempt to connect the Link. If connect fails, then the opposite node already has a connection to us.
// This may occur during connection if the opposite end registered its Link prior to us doing so. In such
// a circumstance, the Link should eventually appear in the LinkManager.
if (!toReturn.connect())
{
// Connect failed. Get NodeID of remote Node (this will have been set during the connect operation)
NodeID remoteID = toReturn.getRemoteNodeID();
// Log failed connect
Node.log.log(typeof(LinkFactory), "Failed to connect to " + remoteID.toString());
// Set the Link to return to null
toReturn = null;
// Loop until the Link is connected. This is a possible weakness. Although it is believed that the
// opposite end will eventually connect, we may have a problem if this continually loops. For information,
// log every attempt.
while (toReturn == null)
{
try
{
// Go to sleep for a bit, and give the Link a chance to register
Thread.Sleep(100);
// Log start of attempt
Node.log.log(typeof(LinkFactory), "Attempting to retrieve Link to " + remoteID.toString());
// Retrieve Link from LinkManager
toReturn = LinkManager.getInstance().requestLink(remoteID);
}
catch (ThreadInterruptedException ie)
{
// Ignore. Should never really happen
}
}
// Return the Link retrieved from the LinkManager
return(toReturn);
}
// Connection succeeded. Register Link with the LinkManager
toReturn.registerLink();
// Now start the Link
ProcessManager proc = new ProcessManager(toReturn);
proc.setPriority(toReturn.priority);
proc.start();
// Return the Link
return(toReturn);
}