public bool add(RequestObject obj)
{
return(this.queue.Add(obj));
}
//this will call by others
//@Override
public String requestAddPermission(String requesterId, int requesterLogicalClock, String requesterHostUrl, int requesterHostPort)
{
//the clock will manage here too
//this will call by others to send [req<id,clock>] to this host
//By receiving a req message we will send a true that mean we receive your message
//if we want to accept the request at time we will send a OK instead
//we must implement this pseudocode
// *********************************************
// if (not accessing resource and do not want to access it)
// send OK
// else if (currently using resource)
// queue request
// else if (want to access resource too)
// if (timestamp of request is smaller)
// send OK
// else //own timestamp is smaller
// queue request
// *********************************************
try{
if (!ServerStatus.getServerStatus())
{
return(null);
}
long id = Convert.ToInt64(requesterId);
HostUrl hostUrl = new HostUrl(requesterHostUrl, requesterHostPort);
RequestObject requestObject = new RequestObject(id, requesterLogicalClock, hostUrl);
//the clock will correct in the constructor of ExternalLampartClock class based on following rule
//LC = Max(LC, LCsender) + 1
String response = null;
if (currentAddRequest == null) //if not accessing resource and do not want to access it --> send OK
{
ExtendedLamportClockObject ELC = new ExtendedLamportClockObject(); //for increasing clock before send
response = "true" + "\n"; //Send 'OK'
response += " ID:&@[" + ELC.getIdString() + "]#! ";
response += " LC:&@[" + ELC.getLogicalClock() + "]#! ";
return(response);
}
else if (!currentAddRequest.isWaiting()) //if currently using resource
{
addRequestsQueue.add(requestObject);
response = "false" + "\n"; //Send 'NOKEY'//means 'you have to wait for me'
return(response);
}
else //if want to access resource too [(currentAddRequest != null) && (currentAddRequest.isWaiting() == true)]
{
if (requestObject.getELCO().compare(currentAddRequest.getELCO()) < 0) //if timestamp of requester is smaller
{
ExtendedLamportClockObject ELC = new ExtendedLamportClockObject(); //for increasing clock before send
response = "true" + "\n"; //Send 'OK'
response += " ID:&@[" + ELC.getIdString() + "]#! ";
response += " LC:&@[" + ELC.getLogicalClock() + "]#! ";
return(response);
}
else //if own timestamp is smaller
{
addRequestsQueue.add(requestObject);
response = "false" + "\n"; //Send 'OK'//means 'you have to wait for me'
return(response);
}
}
}catch (Exception) { return(null); }
}
