public void Propose(TValue value, int csn)
{
if (!isRunning)
{
return;
}
if (reProposers.ContainsKey(csn))
{
reProposers[csn].Kill();
reProposers.Remove(csn);
}
numAcceptRequests[csn] = 0;
Proposal <TValue> proposal = new Proposal <TValue>(csn, psn, value);
reProposers.Add(csn, new NodeReProposer <TValue>(this.Propose, proposal));
proposals[csn] = proposal;
Broadcast(new PrepareRequestMessage(csn, psn));
psn += _nodes.Count;
}
public PrepareResponseMessage(int csn, int minPsn, Proposal <TValue> proposal)
{
this.proposal = proposal;
this.minPsn = minPsn;
this.csn = csn;
}
public NodeReProposer(Action <TValue, int> propose, Proposal <TValue> proposal)
{
this.isRunning = true;
this._propose = propose;
this.proposal = proposal;
}
/// <summary>
/// Serialized Node Message Pump
/// </summary>
/// <param name="m"></param>
private void Deliver(Message m)
{
lock (_nodeLock)
{
if (!isRunning)
{
return;
}
if (m is HeartbeatMessage)
{
// drop own heartbeats
if (m.Sender == this._location)
{
return;
}
_heartbeatObservers[m.Sender.getNum()].ResetTimeout();
}
else if (m is PrepareRequestMessage)
// Acceptor
{
PrepareRequestMessage prepareRequest = (PrepareRequestMessage)m;
int csn = prepareRequest.getCsn();
int psn = prepareRequest.getPsn();
if (currentCsn <= csn)
{
currentCsn = csn + 1;
}
Utility.WriteDebug("Got Prepare Request from " + prepareRequest.Sender + ": (" + csn + ", " + psn + ")");
// new minPsn
if (!minPsns.ContainsKey(csn) || minPsns[csn] < psn)
{
minPsns[csn] = psn;
}
// respond
Proposal <TValue> responseProposalAccepted = maxAcceptedProposals.ContainsKey(csn) ? maxAcceptedProposals[csn] : null;
PrepareResponseMessage <TValue> prepareResponse = new PrepareResponseMessage <TValue>(csn, minPsns[csn], responseProposalAccepted);
prepareResponse.Sender = _location;
Unicast(prepareRequest.Sender, prepareResponse);
UpdateStableStorage();
}
else if (m is PrepareResponseMessage <TValue> )
// Proposer
{
PrepareResponseMessage <TValue> prepareResponse = (PrepareResponseMessage <TValue>)m;
Proposal <TValue> acceptedProposal = prepareResponse.getProposal();
int csn = prepareResponse.getCsn();
int minPsn = prepareResponse.getMinPsn();
Proposal <TValue> proposal = proposals[csn];
if (currentCsn <= csn)
{
currentCsn = csn + 1;
}
Utility.WriteDebug("Got Prepare Response from " + prepareResponse.Sender + ": " + csn + ", " + minPsn + ", " + (acceptedProposal == null ? "None" : acceptedProposal.toString()));
if (!numAcceptRequests.ContainsKey(csn))
{
// ignore if already heard from a majority
return;
}
// if acceptors already accepted something higher, use it instead
if (acceptedProposal != null && acceptedProposal.getPsn() > proposal.getPsn())
{
proposal = acceptedProposal;
}
// if acceptors already promised something higher, use higher psn
if (minPsn > proposal.getPsn())
{
while (psn < prepareResponse.getMinPsn())
{
psn += _nodes.Count;
}
Propose(proposal.getValue(), proposal.getCsn());
return;
}
int n = numAcceptRequests[csn];
n++;
if (n > (_nodes.Count / 2))
// has heard from majority?
{
numAcceptRequests.Remove(csn);
if (reProposers.ContainsKey(csn))
{
reProposers[csn].Kill();
reProposers.Remove(csn);
}
AcceptRequestMessage <TValue> acceptRequest = new AcceptRequestMessage <TValue>(proposal);
Broadcast(acceptRequest);
}
else
{
numAcceptRequests[csn] = n;
}
}
else if (m is AcceptRequestMessage <TValue> ) // Acceptor
{
AcceptRequestMessage <TValue> acceptRequest = (AcceptRequestMessage <TValue>)m;
Proposal <TValue> requestedProposal = acceptRequest.getProposal();
int csn = requestedProposal.getCsn();
int psn = requestedProposal.getPsn();
if (currentCsn <= csn)
{
currentCsn = csn + 1;
}
Utility.WriteDebug("Got Accept Request from " + acceptRequest.Sender + ": " + requestedProposal.toString());
if (psn < minPsns[csn])
{
return; // ignore
}
// "accept" the proposal
if (psn > minPsns[csn])
{
minPsns[csn] = psn;
}
maxAcceptedProposals[csn] = requestedProposal;
Utility.WriteDebug("Accepted: " + requestedProposal.toString());
// Notify Learners
AcceptNotificationMessage <TValue> acceptNotification = new AcceptNotificationMessage <TValue>(requestedProposal);
Broadcast(acceptNotification);
UpdateStableStorage();
}
else if (m is AcceptNotificationMessage <TValue> )
// Learner
{
AcceptNotificationMessage <TValue> acceptNotification = (AcceptNotificationMessage <TValue>)m;
Proposal <TValue> acceptedProposal = acceptNotification.Proposal;
int csn = acceptedProposal.getCsn();
if (currentCsn <= csn)
{
currentCsn = csn + 1;
}
Utility.WriteDebug("Got Accept Notification from " + acceptNotification.Sender + ": " + (acceptedProposal == null ? "None" : acceptedProposal.toString()));
// ignore if already learned
if (_chosenValues.ContainsKey(csn))
{
return;
}
if (!_numAcceptNotifications.ContainsKey(csn))
{
_numAcceptNotifications[csn] = 0;
}
int n = _numAcceptNotifications[csn];
n++;
if (n > (_nodes.Count / 2)) // has heard from majority?
{
_numAcceptNotifications.Remove(csn);
_chosenValues[csn] = acceptedProposal.getValue();
Utility.WriteDebug("Learned: " + acceptedProposal.getCsn() + ", " + acceptedProposal.getValue());
UpdateStableStorage();
}
else
{
_numAcceptNotifications[csn] = n;
}
}
else if (m is NewLeaderNotificationMessage) // Leader Election
{
NewLeaderNotificationMessage newLeaderNotification = (NewLeaderNotificationMessage)m;
int newNum = newLeaderNotification.getNum();
Utility.WriteDebug("Got New Leader Notification from " + newLeaderNotification.Sender + ": " + newNum);
// am i new leader?
if (_location.getNum() == newNum)
{
BecomeLeader();
}
// find new leader, make others non-leaders
foreach (NodeLocation node in _nodes)
{
if (node.getNum() == newNum)
{
node.becomeLeader();
}
else
{
node.becomeNonLeader();
}
}
}
else
{
Utility.WriteDebug("Unknown Message recieved", true);
}
}
}
public AcceptNotificationMessage(Proposal <TValue> proposal)
{
this.proposal = proposal;
}
public AcceptRequestMessage(Proposal <TValue> proposal)
{
this.proposal = proposal;
}