From 5f7d655d7d04e144c5410787753bd889b80c9a18 Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Sun, 2 Dec 2012 15:52:09 -0800
Subject: [PATCH] Structures to track state of features.

---
 src/cpp/ripple/FeatureTable.cpp | 61 ++++++++++++++++++++++++++++++
 src/cpp/ripple/FeatureTable.h   | 67 +++++++++++++++++++++++++++++++++
 2 files changed, 128 insertions(+)
 create mode 100644 src/cpp/ripple/FeatureTable.cpp
 create mode 100644 src/cpp/ripple/FeatureTable.h

diff --git a/src/cpp/ripple/FeatureTable.cpp b/src/cpp/ripple/FeatureTable.cpp
new file mode 100644
index 0000000000..ebf4d268b5
--- /dev/null
+++ b/src/cpp/ripple/FeatureTable.cpp
@@ -0,0 +1,61 @@
+#include "FeatureTable.h"
+
+FeatureTable::FeatureState* FeatureTable::getCreateFeature(const uint256& feature, bool create)
+{ // call with the mutex held
+	featureMap_t::iterator it = mFeatureMap.find(feature);
+	if (it == mFeatureMap.end())
+	{
+		if (!create)
+			return NULL;
+		return &(mFeatureMap[feature]);
+	}
+	return &(it->second);
+}
+
+bool FeatureTable::vetoFeature(const uint256& feature)
+{
+	boost::mutex::scoped_lock sl(mMutex);
+	FeatureState *s = getCreateFeature(feature, true);
+	if (s->mVetoed)
+		return false;
+	s->mVetoed = true;
+	return true;
+}
+
+bool FeatureTable::unVetoFeature(const uint256& feature)
+{
+	boost::mutex::scoped_lock sl(mMutex);
+	FeatureState *s = getCreateFeature(feature, false);
+	if (!s || !s->mVetoed)
+		return false;
+	s->mVetoed = false;
+	return true;
+}
+
+bool FeatureTable::enableFeature(const uint256& feature)
+{
+	boost::mutex::scoped_lock sl(mMutex);
+	FeatureState *s = getCreateFeature(feature, true);
+	if (s->mEnabled)
+		return false;
+	s->mEnabled = true;
+	return true;
+}
+
+bool FeatureTable::disableFeature(const uint256& feature)
+{
+	boost::mutex::scoped_lock sl(mMutex);
+	FeatureState *s = getCreateFeature(feature, false);
+	if (!s || !s->mEnabled)
+		return false;
+	s->mEnabled = false;
+	return true;
+}
+
+bool FeatureTable::isFeatureEnabled(const uint256& feature)
+{
+	boost::mutex::scoped_lock sl(mMutex);
+	FeatureState *s = getCreateFeature(feature, false);
+	return s && s->mEnabled;
+}
+
diff --git a/src/cpp/ripple/FeatureTable.h b/src/cpp/ripple/FeatureTable.h
new file mode 100644
index 0000000000..fa268700a7
--- /dev/null
+++ b/src/cpp/ripple/FeatureTable.h
@@ -0,0 +1,67 @@
+#ifndef FEATURETABLE__H
+#define FEATURETABLE__H
+
+#include <boost/unordered_map.hpp>
+#include <boost/unordered_set.hpp>
+#include <boost/thread/mutex.hpp>
+
+#include "uint256.h"
+
+struct FeatureSet
+{ // the status of all features requested in a given window
+	uint32	mLedgerSequence;
+	uint32	mCloseTime;
+	int		mTrustedValidations;				// number of trusted validations
+
+	boost::unordered_map<uint256, int> mVotes;	// yes votes by feature
+};
+
+class FeatureTable
+{
+protected:
+
+	class FeatureState
+	{
+	public:
+		bool	mVetoed;			// We don't want this feature enabled
+		bool	mEnabled;
+
+		int		mEnableVotes;		// Trusted votes to enable this feature
+		int		mDisableVotes;		// Trusted votes to disable this feature
+		uint32	mFirstMajority;		// First time we saw a majority (ledger sequence)
+		uint32	mLastMajority;		// Most recent time we saw a majority
+
+		FeatureState() : mVetoed(false), mEnabled(false), mEnableVotes(0), mDisableVotes(0),
+			mFirstMajority(0), mLastMajority(0) { ; }
+	};
+
+	typedef boost::unordered_map<uint256, FeatureState> featureMap_t;
+	typedef boost::unordered_set<uint256> featureList_t;
+
+	boost::mutex	mMutex;
+	featureMap_t	mFeatureMap;
+	int				mMajorityTime;		// Seconds a feature must hold a majority
+	int				mMajorityFraction;	// 256 = 100%
+
+	FeatureState*	getCreateFeature(const uint256& feature, bool create);
+
+public:
+
+	FeatureTable(uint32 majorityTime, int mMajorityFraction) : mMajorityTime(majorityTime) { ; }
+
+	bool vetoFeature(const uint256& feature);
+	bool unVetoFeature(const uint256& feature);
+
+	bool enableFeature(const uint256& feature);
+	bool disableFeature(const uint256& feature);
+
+	bool isFeatureEnabled(const uint256& feature);
+
+	featureList_t getVetoedFeatures();
+	featureList_t getEnabledFeatures();
+	featureList_t getFeaturesToEnable(uint32 sequence);	// gets features we would vote to enable
+
+	void reportValidations(const FeatureSet&);
+};
+
+#endif