From adf4ff998becf6b74fe8738761fb00315893d362 Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Fri, 7 Sep 2012 11:23:06 -0700
Subject: [PATCH] Make it less likely that a node will get temporarily stuck in
 a stale consensus process.

---
 src/LedgerConsensus.cpp | 28 ++++++++++++++++++++++++++--
 src/LedgerConsensus.h   |  3 +++
 src/LedgerProposal.cpp  | 16 ++++++++++++++--
 src/LedgerProposal.h    |  2 ++
 4 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/src/LedgerConsensus.cpp b/src/LedgerConsensus.cpp
index 5130d398c5..6500a1ff37 100644
--- a/src/LedgerConsensus.cpp
+++ b/src/LedgerConsensus.cpp
@@ -321,12 +321,19 @@ void LedgerConsensus::handleLCL(const uint256& lclHash)
 			BOOST_FOREACH(Peer::ref peer, peerList)
 				mAcquiringLedger->peerHas(peer);
 		}
+		if (mHaveCorrectLCL && mProposing)
+		{
+			Log(lsINFO) << "Bowing out of consensus";
+			mOurPosition->bowOut();
+			propose();
+		}
 		mHaveCorrectLCL = false;
 		mProposing = false;
 		mValidating = false;
 		mCloseTimes.clear();
 		mPeerPositions.clear();
 		mDisputes.clear();
+		mDeadNodes.clear();
 		return;
 	}
 
@@ -794,11 +801,18 @@ void LedgerConsensus::addDisputedTransaction(const uint256& txID, const std::vec
 
 bool LedgerConsensus::peerPosition(const LedgerProposal::pointer& newPosition)
 {
-	LedgerProposal::pointer& currentPosition = mPeerPositions[newPosition->getPeerID()];
+	uint160 peerID = newPosition->getPeerID();
+	if (mDeadNodes.find(peerID) != mDeadNodes.end())
+	{
+		Log(lsINFO) << "Position from dead node";
+		return false;
+	}
+
+	LedgerProposal::pointer& currentPosition = mPeerPositions[peerID];
 
 	if (currentPosition)
 	{
-		assert(newPosition->getPeerID() == currentPosition->getPeerID());
+		assert(peerID == currentPosition->getPeerID());
 		if (newPosition->getProposeSeq() <= currentPosition->getProposeSeq())
 			return false;
 	}
@@ -808,9 +822,19 @@ bool LedgerConsensus::peerPosition(const LedgerProposal::pointer& newPosition)
 		Log(lsTRACE) << "Peer reports close time as " << newPosition->getCloseTime();
 		++mCloseTimes[newPosition->getCloseTime()];
 	}
+	else if (newPosition->getProposeSeq() == LedgerProposal::seqLeave)
+	{
+		BOOST_FOREACH(u256_lct_pair& it, mDisputes)
+			it.second->unVote(peerID);
+		mPeerPositions.erase(peerID);
+		mDeadNodes.insert(peerID);
+		return true;
+	}
+
 
 	Log(lsINFO) << "Processing peer proposal " << newPosition->getProposeSeq() << "/" << newPosition->getCurrentHash();
 	currentPosition = newPosition;
+
 	SHAMap::pointer set = getTransactionTree(newPosition->getCurrentHash(), true);
 	if (set)
 	{
diff --git a/src/LedgerConsensus.h b/src/LedgerConsensus.h
index 4e1db172dd..17aa02691d 100644
--- a/src/LedgerConsensus.h
+++ b/src/LedgerConsensus.h
@@ -115,6 +115,9 @@ protected:
 	// deferred proposals (node ID -> proposals from that peer)
 	boost::unordered_map< uint160,  std::list<LedgerProposal::pointer> > mDeferredProposals;
 
+	// nodes that have bowed out of this consensus process
+	boost::unordered_set<uint160> mDeadNodes;
+
 	// final accept logic
 	static void Saccept(boost::shared_ptr<LedgerConsensus> This, SHAMap::pointer txSet);
 	void accept(const SHAMap::pointer& txSet);
diff --git a/src/LedgerProposal.cpp b/src/LedgerProposal.cpp
index d96b397434..5840c10372 100644
--- a/src/LedgerProposal.cpp
+++ b/src/LedgerProposal.cpp
@@ -62,6 +62,13 @@ void LedgerProposal::changePosition(const uint256& newPosition, uint32 closeTime
 	++mProposeSeq;
 }
 
+void LedgerProposal::bowOut()
+{
+	mCurrentHash	= uint256();
+	mTime			= boost::posix_time::second_clock::universal_time();
+	mProposeSeq		= seqLeave;
+}
+
 std::vector<unsigned char> LedgerProposal::sign(void)
 {
 	std::vector<unsigned char> ret;
@@ -78,9 +85,14 @@ Json::Value LedgerProposal::getJson() const
 {
 	Json::Value ret = Json::objectValue;
 	ret["previous_ledger"] = mPreviousLedger.GetHex();
-	ret["transaction_hash"] = mCurrentHash.GetHex();
+
+	if (mProposeSeq != seqLeave)
+	{
+		ret["transaction_hash"] = mCurrentHash.GetHex();
+		ret["propose_seq"] = mProposeSeq;
+	}
+
 	ret["close_time"] = mCloseTime;
-	ret["propose_seq"] = mProposeSeq;
 
 	if (mPublicKey.isValid())
 		ret["peer_id"] = mPublicKey.humanNodePublic();
diff --git a/src/LedgerProposal.h b/src/LedgerProposal.h
index 74d0f7c071..adaa557719 100644
--- a/src/LedgerProposal.h
+++ b/src/LedgerProposal.h
@@ -26,6 +26,7 @@ protected:
 	boost::posix_time::ptime	mTime;
 
 public:
+	static const uint32 seqLeave = 0xffffffff; // leaving the consensus process
 
 	typedef boost::shared_ptr<LedgerProposal> pointer;
 
@@ -63,6 +64,7 @@ public:
 	bool isStale(boost::posix_time::ptime cutoff)	{ return mTime <= cutoff; }
 
 	void changePosition(const uint256& newPosition, uint32 newCloseTime);
+	void bowOut();
 	Json::Value getJson() const;
 };