From c1c02c461d3912da502d05c338b8f8b6502dfc6f Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Mon, 3 Mar 2014 18:54:31 +0000
Subject: [PATCH] Remove Database when protocol version changes.

---
 libethereum/Client.cpp      | 30 +++++++++++++++++++++++++++---
 libethereum/Client.h        | 15 +++++++++++++++
 libethereum/Defaults.h      |  1 +
 libethereum/PeerNetwork.cpp | 10 ++++++++++
 libethereum/PeerNetwork.h   |  3 +++
 libethereum/State.cpp       |  2 --
 6 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index c30de604f..1752c2c0e 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -23,20 +23,44 @@
 
 #include <chrono>
 #include <thread>
+#include <boost/filesystem.hpp>
 #include "Common.h"
 #include "Defaults.h"
 using namespace std;
 using namespace eth;
 
+VersionChecker::VersionChecker(string const& _dbPath, unsigned _protocolVersion):
+	m_path(_dbPath.size() ? _dbPath : Defaults::dbPath()),
+	m_protocolVersion(_protocolVersion)
+{
+	m_ok = RLP(contents(m_path + "/protocol")).toInt<unsigned>(RLP::LaisezFaire) == _protocolVersion;
+}
+
+void VersionChecker::setOk()
+{
+	if (!m_ok)
+	{
+		try
+		{
+			boost::filesystem::create_directory(m_path);
+		}
+		catch (...) {}
+		writeFile(m_path + "/protocol", rlp(m_protocolVersion));
+	}
+}
+
 Client::Client(std::string const& _clientVersion, Address _us, std::string const& _dbPath):
 	m_clientVersion(_clientVersion),
-	m_bc(_dbPath),
-	m_stateDB(State::openDB(_dbPath)),
+	m_vc(_dbPath, PeerSession::protocolVersion()),
+	m_bc(_dbPath, !m_vc.ok()),
+	m_stateDB(State::openDB(_dbPath, !m_vc.ok())),
 	m_preMine(_us, m_stateDB),
 	m_postMine(_us, m_stateDB),
 	m_workState(Active)
 {
-	Defaults::setDBPath(_dbPath);
+	if (_dbPath.size())
+		Defaults::setDBPath(_dbPath);
+	m_vc.setOk();
 
 	// Synchronise the state according to the head of the block chain.
 	// TODO: currently it contains keys for *all* blocks. Make it remove old ones.
diff --git a/libethereum/Client.h b/libethereum/Client.h
index bf1964fe0..5bcfe10fa 100644
--- a/libethereum/Client.h
+++ b/libethereum/Client.h
@@ -60,6 +60,20 @@ enum ClientWorkState
 	Deleted
 };
 
+class VersionChecker
+{
+public:
+	VersionChecker(std::string const& _dbPath, unsigned _protocolVersion);
+
+	void setOk();
+	bool ok() const { return m_ok; }
+
+private:
+	bool m_ok;
+	std::string m_path;
+	unsigned m_protocolVersion;
+};
+
 class Client
 {
 public:
@@ -141,6 +155,7 @@ private:
 	void work();
 
 	std::string m_clientVersion;		///< Our end-application client's name/version.
+	VersionChecker m_vc;				///< Dummy object to check & update the protocol version.
 	BlockChain m_bc;					///< Maintains block database.
 	TransactionQueue m_tq;				///< Maintains list of incoming transactions not yet on the block chain.
 	Overlay m_stateDB;					///< Acts as the central point for the state database, so multiple States can share it.
diff --git a/libethereum/Defaults.h b/libethereum/Defaults.h
index ce0c27a42..0d8e84515 100644
--- a/libethereum/Defaults.h
+++ b/libethereum/Defaults.h
@@ -36,6 +36,7 @@ public:
 
 	static Defaults* get() { if (!s_this) s_this = new Defaults; return s_this; }
 	static void setDBPath(std::string const& _dbPath) { get()->m_dbPath = _dbPath; }
+	static std::string const& dbPath() { return get()->m_dbPath; }
 
 private:
 	std::string m_dbPath;
diff --git a/libethereum/PeerNetwork.cpp b/libethereum/PeerNetwork.cpp
index 713441de4..a4e3c6317 100644
--- a/libethereum/PeerNetwork.cpp
+++ b/libethereum/PeerNetwork.cpp
@@ -97,6 +97,16 @@ PeerSession::~PeerSession()
 	m_socket.close();
 }
 
+int PeerSession::protocolVersion()
+{
+	return c_protocolVersion;
+}
+
+int PeerSession::networkId()
+{
+	return 0;
+}
+
 bi::tcp::endpoint PeerSession::endpoint() const
 {
 	if (m_socket.is_open())
diff --git a/libethereum/PeerNetwork.h b/libethereum/PeerNetwork.h
index 80c6b054c..aa5f42da7 100644
--- a/libethereum/PeerNetwork.h
+++ b/libethereum/PeerNetwork.h
@@ -101,6 +101,9 @@ public:
 
 	bool isOpen() const { return m_socket.is_open(); }
 
+	static int protocolVersion();
+	static int networkId();
+
 	bi::tcp::endpoint endpoint() const;	///< for other peers to connect to.
 
 private:
diff --git a/libethereum/State.cpp b/libethereum/State.cpp
index f14c8c18c..c06453c6f 100644
--- a/libethereum/State.cpp
+++ b/libethereum/State.cpp
@@ -55,8 +55,6 @@ Overlay State::openDB(std::string _path, bool _killExisting)
 	if (_path.empty())
 		_path = Defaults::get()->m_dbPath;
 	boost::filesystem::create_directory(_path);
-	if (_killExisting)
-		boost::filesystem::remove_all(_path + "/state");
 
 	ldb::Options o;
 	o.create_if_missing = true;