void ReplicatedLog::OnRequest(PaxosMessage& imsg)
{
Log_Trace();
Buffer value;
PaxosMessage omsg;
if (imsg.paxosID < GetPaxosID())
{
// the node is lagging and needs to catch-up
context->GetDatabase()->GetAcceptedValue(imsg.paxosID, value);
if (value.GetLength() == 0)
return;
omsg.LearnValue(imsg.paxosID, MY_NODEID, 0, value);
context->GetTransport()->SendMessage(imsg.nodeID, omsg);
}
else if (GetPaxosID() < imsg.paxosID)
{
// I am lagging and need to catch-up
RequestChosen(imsg.nodeID);
}
}
void ReplicatedLog::Append(Buffer& value)
{
Log_Trace();
if (proposer.IsActive() || proposer.IsLearnSent())
return;
context->OnStartProposing();
proposer.Propose(value);
#ifdef RLOG_DEBUG_MESSAGES
Log_Debug("Proposing for paxosID = %U", GetPaxosID());
#endif
}
bool ReplicatedLog::OnRequestChosen(PaxosMessage& imsg)
{
Buffer value;
PaxosMessage omsg;
#ifdef RLOG_DEBUG_MESSAGES
Log_Debug("ReplicatedLog::OnRequestChosen, imsg.paxosID = %U, mine = %U",
imsg.paxosID, GetPaxosID());
#endif
if (imsg.paxosID >= GetPaxosID())
return true;
// the node is lagging and needs to catch-up
if (context->AlwaysUseDatabaseCatchup() && imsg.paxosID < GetPaxosID())
{
omsg.StartCatchup(paxosID, MY_NODEID);
}
else
{
context->GetDatabase()->GetAcceptedValue(imsg.paxosID, value);
if (value.GetLength() > 0)
{
Log_Trace("Sending paxosID %d to node %d", imsg.paxosID, imsg.nodeID);
omsg.LearnValue(imsg.paxosID, MY_NODEID, 0, value);
}
else
{
Log_Trace("Node requested a paxosID I no longer have");
omsg.StartCatchup(paxosID, MY_NODEID);
}
}
context->GetTransport()->SendMessage(imsg.nodeID, omsg);
return true;
}
void ReplicatedLog::Continue()
{
if (context->IsLeaseKnown() && context->GetHighestPaxosID() > GetPaxosID())
RequestChosen(context->GetLeaseOwner());
}