From e25863207a95a3e1d9505ad19b325cc29d8e620b Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Wed, 23 Jan 2013 10:14:20 -0800
Subject: [PATCH] An assert in NetworkOPs.cpp line 850 was reported. This
 suggests a mutable ledger came from the ledger master's "ledger by hash"
 table. This fixes an obvious way that this can happen (that seems incredibly
 rare and requires a transaction / ledger acquire race with a very narrow
 window) and adds some extra asserts to try to catch this earlier.

---
 src/cpp/ripple/LedgerHistory.cpp | 5 +++++
 src/cpp/ripple/LedgerMaster.h    | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/cpp/ripple/LedgerHistory.cpp b/src/cpp/ripple/LedgerHistory.cpp
index 34a0d05d8d..dc30e87e3e 100644
--- a/src/cpp/ripple/LedgerHistory.cpp
+++ b/src/cpp/ripple/LedgerHistory.cpp
@@ -24,6 +24,7 @@ LedgerHistory::LedgerHistory() : mLedgersByHash("LedgerCache", CACHED_LEDGER_NUM
 
 void LedgerHistory::addLedger(Ledger::pointer ledger)
 {
+	assert(ledger->isImmutable());
 	mLedgersByHash.canonicalize(ledger->getHash(), ledger, true);
 }
 
@@ -78,13 +79,17 @@ Ledger::pointer LedgerHistory::getLedgerByHash(const uint256& hash)
 {
 	Ledger::pointer ret = mLedgersByHash.fetch(hash);
 	if (ret)
+	{
+		assert(ret->getHash() == hash);
 		return ret;
+	}
 
 	ret = Ledger::loadByHash(hash);
 	if (!ret)
 		return ret;
 	assert(ret->getHash() == hash);
 	mLedgersByHash.canonicalize(ret->getHash(), ret);
+	assert(ret->getHash() == hash);
 
 	return ret;
 }
diff --git a/src/cpp/ripple/LedgerMaster.h b/src/cpp/ripple/LedgerMaster.h
index 514b055517..dac64c862e 100644
--- a/src/cpp/ripple/LedgerMaster.h
+++ b/src/cpp/ripple/LedgerMaster.h
@@ -105,10 +105,11 @@ public:
 	Ledger::pointer getLedgerByHash(const uint256& hash)
 	{
 		if (hash.isZero())
-			return mCurrentLedger;
+			return boost::make_shared<Ledger>(boost::ref(*mCurrentLedger), false);
 
 		if (mCurrentLedger && (mCurrentLedger->getHash() == hash))
-			return mCurrentLedger;
+			return boost::make_shared<Ledger>(boost::ref(*mCurrentLedger), false);
+
 		if (mFinalizedLedger && (mFinalizedLedger->getHash() == hash))
 			return mFinalizedLedger;