From 80144bb96b7f4fb8b467494364699c67977ed427 Mon Sep 17 00:00:00 2001
From: Scott Nadal <scott.nadal@gmail.com>
Date: Tue, 19 Jun 2012 15:55:38 +0100
Subject: [PATCH] PPCoin: Force reorganization for synchronized checkpoint

---
 src/checkpoints.cpp |   73 +++++++++++++++++++++++++++++++++++++++++----------
 src/main.cpp        |    2 +-
 src/main.h          |    1 +
 3 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/src/checkpoints.cpp b/src/checkpoints.cpp
index 888d106..283bbdd 100644
--- a/src/checkpoints.cpp
+++ b/src/checkpoints.cpp
@@ -86,7 +86,12 @@ namespace Checkpoints
 
     bool AcceptPendingSyncCheckpoint()
     {
+        bool fAccepted = false;
+        uint256 hashCheckpoint = 0;
+        CTxDB txdb;
+
         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+        {
             if ((!checkpointMessagePending.IsNull()) && mapBlockIndex.count(checkpointMessagePending.hashCheckpoint))
             {
                 if (!ValidateSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
@@ -95,22 +100,45 @@ namespace Checkpoints
                     return false;
                 }
 
-                CTxDB txdb;
+                txdb.TxnBegin();
                 if (!txdb.WriteSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
+                {
+                    txdb.TxnAbort();
                     return error("AcceptPendingSyncCheckpoint() : failed to write to db sync checkpoint %s\n", checkpointMessagePending.hashCheckpoint.ToString().c_str());
-                txdb.Close();
+                }
+                if (!txdb.TxnCommit())
+                    return error("AcceptPendingSyncCheckpoint() : failed to commit to db sync checkpoint %s\n", checkpointMessagePending.hashCheckpoint.ToString().c_str());
 
                 hashSyncCheckpoint = checkpointMessagePending.hashCheckpoint;
                 checkpointMessage = checkpointMessagePending;
                 checkpointMessagePending.SetNull();
                 printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
-                // relay the checkpoint
-                BOOST_FOREACH(CNode* pnode, vNodes)
-                    checkpointMessage.RelayTo(pnode);
-                return true;
+                fAccepted = true;
+                hashCheckpoint = hashSyncCheckpoint;
             }
+        }
 
-        return false;
+        if (fAccepted)
+        {
+            CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
+            if (!pindexCheckpoint->IsInMainChain())
+            {
+                txdb.TxnBegin();
+                if (!Reorganize(txdb, pindexCheckpoint))
+                {
+                    txdb.TxnAbort();
+                    return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
+                }
+            }
+        }
+        txdb.Close();
+
+        // relay the checkpoint
+        CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+            BOOST_FOREACH(CNode* pnode, vNodes)
+                checkpointMessage.RelayTo(pnode);
+
+        return fAccepted;
     }
 
     uint256 AutoSelectSyncCheckpoint()
@@ -276,13 +304,14 @@ bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
     if (!CheckSignature())
         return false;
 
+    CTxDB txdb;
     CRITICAL_BLOCK(Checkpoints::cs_hashSyncCheckpoint)
     {
         if (!mapBlockIndex.count(hashCheckpoint))
         {
             // We haven't accepted this block, keep the checkpoint as pending
             Checkpoints::checkpointMessagePending = *this;
-            printf("ProcessSyncCheckpoint : pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
+            printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
             // Ask this guy to fill in what we're missing
             if (pfrom)
                 pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
@@ -291,15 +320,31 @@ bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
         if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
             return false;
 
-        CTxDB txdb;
-        if (!txdb.WriteSyncCheckpoint(this->hashCheckpoint))
-            return error("ProcessSyncCheckpoint() : failed to write to db sync checkpoint %s\n", this->hashCheckpoint.ToString().c_str());
-        txdb.Close();
+        txdb.TxnBegin();
+        if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
+        {
+            txdb.TxnAbort();
+            return error("ProcessSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
+        }
+        if (!txdb.TxnCommit())
+            return error("ProcessSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 
-        Checkpoints::hashSyncCheckpoint = this->hashCheckpoint;
+        Checkpoints::hashSyncCheckpoint = hashCheckpoint;
         Checkpoints::checkpointMessage = *this;
         Checkpoints::checkpointMessagePending.SetNull();
-        printf("ProcessSyncCheckpoint : sync-checkpoint at %s\n", Checkpoints::hashSyncCheckpoint.ToString().c_str());
+        printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
+    }
+
+    CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
+    if (!pindexCheckpoint->IsInMainChain())
+    {
+        txdb.TxnBegin();
+        if (!Reorganize(txdb, pindexCheckpoint))
+        {
+            txdb.TxnAbort();
+            return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
+        }
     }
+    txdb.Close();
     return true;
 }
diff --git a/src/main.cpp b/src/main.cpp
index b8d83b2..127ca29 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1125,7 +1125,7 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
     return true;
 }
 
-bool static Reorganize(CTxDB& txdb, CBlockIndex* pindexNew)
+bool Reorganize(CTxDB& txdb, CBlockIndex* pindexNew)
 {
     printf("REORGANIZE\n");
 
diff --git a/src/main.h b/src/main.h
index 2baf7c4..feed1e2 100644
--- a/src/main.h
+++ b/src/main.h
@@ -107,6 +107,7 @@ unsigned int ComputeMinWork(unsigned int nBase, int64 nTime);
 int GetNumBlocksOfPeers();
 bool IsInitialBlockDownload();
 std::string GetWarnings(std::string strFor);
+bool Reorganize(CTxDB& txdb, CBlockIndex* pindexNew);
 
 
 
-- 
1.7.1