From ed787d58cbda5e1690a819a1abde416eb514bdac Mon Sep 17 00:00:00 2001
From: Matias Alejo Garcia <ematiu@gmail.com>
Date: Thu, 6 Mar 2014 00:01:28 -0300
Subject: [PATCH] recover from race condition in interrupted sync

---
 lib/HistoricSync.js  | 37 +++++++++++++++++++++++++++----------
 lib/TransactionDb.js |  1 -
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/lib/HistoricSync.js b/lib/HistoricSync.js
index b87f54a1..75ed2989 100644
--- a/lib/HistoricSync.js
+++ b/lib/HistoricSync.js
@@ -238,22 +238,32 @@ function spec() {
         function(err) {
           if (err) return next(err);
           var ret = false;
-          if ( self.blockChainHeight  === blockInfo.height ||
-              blockInfo.confirmations > 0) {
+          if ( self.blockChainHeight  === blockInfo.height || // Still the tip
+               blockInfo.confirmations > 0) {                 // Or is confirmed
             ret = false;
           }
           else {
             oldtip = tip;
             tip = blockInfo.previousblockhash;
-            assert(tip);
-            p('Previous TIP is now orphan. Back to:' + tip);
-            ret  = true;
+            p('Previous TIP is now orphan.');
+            if (tip) {
+              p('\tGoing back to:' + tip);
+              ret  = true;
+            }
+            else {
+              p('\tNo able to recover last tip. A Total resync is needed.');
+              tip = self.genesis;
+              self.needResync = 1;
+              ret = false;
+            }
           }
           return ret;
         },
         function(err) {
           self.startBlock = tip;
-          p('Resuming sync from block:'+tip);
+          if (!self.needResync) {
+            p('Resuming sync from block:'+tip);
+          }
           return next(err);
         }
       );
@@ -354,15 +364,22 @@ function spec() {
       function(s_c) {
         self.checkNetworkSettings(s_c);
       },
-      function(s_c) {
-        self.updateConnectedCountDB(s_c);
-      },
-      function(s_c) {
+     function(s_c) {
         self.updateBlockChainHeight(s_c);
       },
       function(s_c) {
         self.updateStartBlock(s_c);
       },
+      function(s_c) {
+        if (self.needResync) {
+          self.needResync=0;
+          self.sync.destroy(s_c);
+        }
+        else s_c();
+      },
+      function(s_c) {
+        self.updateConnectedCountDB(s_c);
+      },
       function(s_c) {
         self.prepareFileSync(opts, s_c);
       },
diff --git a/lib/TransactionDb.js b/lib/TransactionDb.js
index 03415402..7c7ac978 100644
--- a/lib/TransactionDb.js
+++ b/lib/TransactionDb.js
@@ -673,7 +673,6 @@ isspent
 
     var k = FROM_BLK_PREFIX + hash;
     var k2 = IN_BLK_PREFIX;
-    // This is slow, but prevent us to create a new block->tx index.
     db.createReadStream({
       start: k,
       end: k + '~'