From 42fb9652f56321d2752ffe7773806df11f3087b8 Mon Sep 17 00:00:00 2001
From: zelig <viktor.tron@gmail.com>
Date: Tue, 7 Apr 2015 18:53:05 +0100
Subject: [PATCH] fix blockpool deadlock - do not break from headsection on
 error [remove peer after protocol quit will close switchC, until then head
 block can arrive and block on channel while keeping peers lock causing a
 deadlock.] - more careful locking in AddBlock

---
 blockpool/blockpool.go      | 20 +++++++++++++++++---
 blockpool/blockpool_test.go |  4 ++++
 blockpool/peers.go          | 10 +---------
 3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/blockpool/blockpool.go b/blockpool/blockpool.go
index 3b3de928d5..9871c50369 100644
--- a/blockpool/blockpool.go
+++ b/blockpool/blockpool.go
@@ -624,6 +624,7 @@ func (self *BlockPool) AddBlock(block *types.Block, peerId string) {
 	entry := self.get(hash)
 
 	// a peer's current head block is appearing the first time
+	sender.lock.Lock()
 	if hash == sender.currentBlockHash {
 		if sender.currentBlock == nil {
 			plog.Debugf("AddBlock: add head block %s for peer <%s> (head: %s)", hex(hash), peerId, hex(sender.currentBlockHash))
@@ -634,16 +635,28 @@ func (self *BlockPool) AddBlock(block *types.Block, peerId string) {
 			self.status.values.Blocks++
 			self.status.values.BlocksInPool++
 			self.status.lock.Unlock()
+			select {
+			case sender.currentBlockC <- block:
+			case <-sender.switchC:
+			}
 		} else {
 			plog.DebugDetailf("AddBlock: head block %s for peer <%s> (head: %s) already known", hex(hash), peerId, hex(sender.currentBlockHash))
 			// signal to head section process
-			sender.currentBlockC <- block
 		}
+		// self.wg.Add(1)
+		// go func() {
+		// 	timeout := time.After(1 * time.Second)
+		// select {
+		// 	case sender.currentBlockC <- block:
+		// 	case <-timeout:
+		// 	}
+		// 	self.wg.Done()
+		// }()
+
 	} else {
 
 		plog.DebugDetailf("AddBlock: block %s received from peer <%s> (head: %s)", hex(hash), peerId, hex(sender.currentBlockHash))
 
-		sender.lock.Lock()
 		// update peer chain info if more recent than what we registered
 		if block.Td != nil && block.Td.Cmp(sender.td) > 0 {
 			sender.td = block.Td
@@ -652,7 +665,6 @@ func (self *BlockPool) AddBlock(block *types.Block, peerId string) {
 			sender.currentBlock = block
 			sender.headSection = nil
 		}
-		sender.lock.Unlock()
 
 		/* @zelig !!!
 		requested 5 hashes from both A & B. A responds sooner then B, process blocks. Close section.
@@ -668,6 +680,8 @@ func (self *BlockPool) AddBlock(block *types.Block, peerId string) {
 			}
 		*/
 	}
+	sender.lock.Unlock()
+
 	if entry == nil {
 		return
 	}
diff --git a/blockpool/blockpool_test.go b/blockpool/blockpool_test.go
index 9bcd72f046..b28c2abbf1 100644
--- a/blockpool/blockpool_test.go
+++ b/blockpool/blockpool_test.go
@@ -7,6 +7,10 @@ import (
 	"github.com/ethereum/go-ethereum/blockpool/test"
 )
 
+func init() {
+	test.LogInit()
+}
+
 // using the mock framework in blockpool_util_test
 // we test various scenarios here
 
diff --git a/blockpool/peers.go b/blockpool/peers.go
index 59225856dc..d95c348a85 100644
--- a/blockpool/peers.go
+++ b/blockpool/peers.go
@@ -142,9 +142,8 @@ func (self *peer) setChainInfo(td *big.Int, c common.Hash) {
 	self.headSection = nil
 }
 
+// caller must hold peer lock
 func (self *peer) setChainInfoFromBlock(block *types.Block) {
-	self.lock.Lock()
-	defer self.lock.Unlock()
 	// use the optional TD to update peer td, this helps second best peer selection
 	// in case best peer is lost
 	if block.Td != nil && block.Td.Cmp(self.td) > 0 {
@@ -155,11 +154,6 @@ func (self *peer) setChainInfoFromBlock(block *types.Block) {
 		self.currentBlock = block
 		self.headSection = nil
 	}
-	self.bp.wg.Add(1)
-	go func() {
-		self.currentBlockC <- block
-		self.bp.wg.Done()
-	}()
 }
 
 // distribute block request among known peers
@@ -571,7 +565,6 @@ LOOP:
 			self.bp.status.badPeers[self.id]++
 			self.bp.status.lock.Unlock()
 			// there is no persistence here, so GC will just take care of cleaning up
-			break LOOP
 
 		// signal for peer switch, quit
 		case <-switchC:
@@ -594,7 +587,6 @@ LOOP:
 			self.bp.status.badPeers[self.id]++
 			self.bp.status.lock.Unlock()
 			plog.Debugf("HeadSection: <%s> (headsection [%s]) quit channel closed : timed out without providing new blocks...quitting", self.id, sectionhex(self.headSection))
-			break LOOP
 		}
 	}
 	if !self.idle {