use own total difficulty to limit best peer

- update blockpool td by subscribing to ChainHeadEvent
- if ahead of best peer, demote it
- addPeer now take own td as current td
- removePeer now take own td as current td
- add relevant tests to peers_test
- eth: backend now calls blockpool with eth.eventMux and chainManager.Td

7 files changed, 87 insertions, 26 deletions

diff --git a/blockpool/blockpool.go b/blockpool/blockpool.go
index ef619b27b..a552e1b72 100644
--- a/blockpool/blockpool.go
+++ b/blockpool/blockpool.go
@@ -7,8 +7,10 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/errs"
+	"github.com/ethereum/go-ethereum/event"
 	ethlogger "github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/pow"
 )
@@ -32,8 +34,9 @@ var (
 	blockHashesTimeout = 60 * time.Second
 	// timeout interval: max time allowed for peer without sending a block
 	blocksTimeout = 60 * time.Second
-	//
-	idleBestPeerTimeout    = 120 * time.Second
+	// timeout interval: max time allowed for best peer to remain idle (not send new block after sync complete)
+	idleBestPeerTimeout = 120 * time.Second
+	// duration of suspension after peer fatal error during which peer is not allowed to reconnect
 	peerSuspensionInterval = 300 * time.Second
 )
 
@@ -131,6 +134,10 @@ type BlockPool struct {
 	hasBlock    func(hash common.Hash) bool
 	insertChain func(types.Blocks) error
 	verifyPoW   func(pow.Block) bool
+	chainEvents *event.TypeMux
+
+	tdSub event.Subscription
+	td    *big.Int
 
 	pool  map[string]*entry
 	peers *peers
@@ -152,6 +159,8 @@ func New(
 	hasBlock func(hash common.Hash) bool,
 	insertChain func(types.Blocks) error,
 	verifyPoW func(pow.Block) bool,
+	chainEvents *event.TypeMux,
+	td *big.Int,
 ) *BlockPool {
 
 	return &BlockPool{
@@ -159,6 +168,8 @@ func New(
 		hasBlock:    hasBlock,
 		insertChain: insertChain,
 		verifyPoW:   verifyPoW,
+		chainEvents: chainEvents,
+		td:          td,
 	}
 }
 
@@ -198,12 +209,29 @@ func (self *BlockPool) Start() {
 		status:    self.status,
 		bp:        self,
 	}
+
+	self.tdSub = self.chainEvents.Subscribe(core.ChainHeadEvent{})
 	timer := time.NewTicker(3 * time.Second)
 	go func() {
 		for {
 			select {
 			case <-self.quit:
 				return
+			case event := <-self.tdSub.Chan():
+				if ev, ok := event.(core.ChainHeadEvent); ok {
+					td := ev.Block.Td
+					plog.DebugDetailf("td: %v", td)
+					self.setTD(td)
+					self.peers.lock.Lock()
+
+					if best := self.peers.best; best != nil {
+						if td.Cmp(best.td) >= 0 {
+							self.peers.best = nil
+							self.switchPeer(best, nil)
+						}
+					}
+					self.peers.lock.Unlock()
+				}
 			case <-timer.C:
 				plog.DebugDetailf("status:\n%v", self.Status())
 			}
@@ -224,6 +252,7 @@ func (self *BlockPool) Stop() {
 
 	plog.Infoln("Stopping...")
 
+	self.tdSub.Unsubscribe()
 	close(self.quit)
 
 	self.lock.Lock()
@@ -736,6 +765,19 @@ func (self *BlockPool) set(hash common.Hash, e *entry) {
 	self.pool[hash.Str()] = e
 }
 
+// accessor and setter for total difficulty
+func (self *BlockPool) getTD() *big.Int {
+	self.lock.RLock()
+	defer self.lock.RUnlock()
+	return self.td
+}
+
+func (self *BlockPool) setTD(td *big.Int) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+	self.td = td
+}
+
 func (self *BlockPool) remove(sec *section) {
 	// delete node entries from pool index under pool lock
 	self.lock.Lock()
diff --git a/blockpool/blockpool_util_test.go b/blockpool/blockpool_util_test.go
index 5ba92066c..a17bc584e 100644
--- a/blockpool/blockpool_util_test.go
+++ b/blockpool/blockpool_util_test.go
@@ -11,6 +11,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/errs"
+	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/pow"
 )
 
@@ -38,6 +39,7 @@ type blockPoolTester struct {
 	blockChain        blockChain
 	blockPool         *BlockPool
 	t                 *testing.T
+	chainEvents       *event.TypeMux
 }
 
 func newTestBlockPool(t *testing.T) (hashPool *test.TestHashPool, blockPool *BlockPool, b *blockPoolTester) {
@@ -48,8 +50,9 @@ func newTestBlockPool(t *testing.T) (hashPool *test.TestHashPool, blockPool *Blo
 		blockChain:        make(blockChain),
 		refBlockChain:     make(blockChain),
 		blocksRequestsMap: make(map[int]bool),
+		chainEvents:       &event.TypeMux{},
 	}
-	b.blockPool = New(b.hasBlock, b.insertChain, b.verifyPoW)
+	b.blockPool = New(b.hasBlock, b.insertChain, b.verifyPoW, b.chainEvents, common.Big0)
 	blockPool = b.blockPool
 	blockPool.Config.BlockHashesRequestInterval = testBlockHashesRequestInterval
 	blockPool.Config.BlocksRequestInterval = testBlocksRequestInterval
diff --git a/blockpool/config_test.go b/blockpool/config_test.go
index 8eeaceb51..2cb93769e 100644
--- a/blockpool/config_test.go
+++ b/blockpool/config_test.go
@@ -5,11 +5,12 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/blockpool/test"
+	"github.com/ethereum/go-ethereum/event"
 )
 
 func TestBlockPoolConfig(t *testing.T) {
 	test.LogInit()
-	blockPool := &BlockPool{Config: &Config{}}
+	blockPool := &BlockPool{Config: &Config{}, chainEvents: &event.TypeMux{}}
 	blockPool.Start()
 	c := blockPool.Config
 	test.CheckInt("BlockHashesBatchSize", c.BlockHashesBatchSize, blockHashesBatchSize, t)
@@ -26,7 +27,7 @@ func TestBlockPoolConfig(t *testing.T) {
 
 func TestBlockPoolOverrideConfig(t *testing.T) {
 	test.LogInit()
-	blockPool := &BlockPool{Config: &Config{}}
+	blockPool := &BlockPool{Config: &Config{}, chainEvents: &event.TypeMux{}}
 	c := &Config{128, 32, 1, 0, 300 * time.Millisecond, 100 * time.Millisecond, 90 * time.Second, 0, 30 * time.Second, 30 * time.Second}
 
 	blockPool.Config = c
diff --git a/blockpool/peers.go b/blockpool/peers.go
index 81bab31e7..41782983c 100644
--- a/blockpool/peers.go
+++ b/blockpool/peers.go
@@ -7,7 +7,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/errs"
 )
@@ -256,7 +255,7 @@ func (self *peers) addPeer(
 		}
 		best = true
 	} else {
-		currentTD := common.Big0
+		currentTD := self.bp.getTD()
 		if self.best != nil {
 			currentTD = self.best.td
 		}
@@ -264,7 +263,7 @@ func (self *peers) addPeer(
 			self.status.lock.Lock()
 			self.status.bestPeers[p.id]++
 			self.status.lock.Unlock()
-			plog.Debugf("addPeer: peer <%v> promoted best peer", id)
+			plog.Debugf("addPeer: peer <%v> (td: %v > current td %v) promoted best peer", id, td, currentTD)
 			self.bp.switchPeer(self.best, p)
 			self.best = p
 			best = true
@@ -275,10 +274,8 @@ func (self *peers) addPeer(
 
 // removePeer is called (via RemovePeer) by the eth protocol when the peer disconnects
 func (self *peers) removePeer(id string) {
-	plog.Debugf("addPeer: remove peer 0 <%v>", id)
 	self.lock.Lock()
 	defer self.lock.Unlock()
-	plog.Debugf("addPeer: remove peer 1 <%v>", id)
 
 	p, found := self.peers[id]
 	if !found {
@@ -286,13 +283,13 @@ func (self *peers) removePeer(id string) {
 	}
 
 	delete(self.peers, id)
-	plog.Debugf("addPeer: remove peer <%v>", id)
+	plog.Debugf("addPeer: remove peer <%v> (td: %v)", id, p.td)
 
 	// if current best peer is removed, need to find a better one
 	if self.best == p {
 		var newp *peer
-		// FIXME: own TD
-		max := common.Big0
+		// only peers that are ahead of us are considered
+		max := self.bp.getTD()
 		// peer with the highest self-acclaimed TD is chosen
 		for _, pp := range self.peers {
 			if pp.td.Cmp(max) > 0 {
@@ -304,7 +301,7 @@ func (self *peers) removePeer(id string) {
 			self.status.lock.Lock()
 			self.status.bestPeers[p.id]++
 			self.status.lock.Unlock()
-			plog.Debugf("addPeer: peer <%v> with td %v promoted best peer", newp.id, newp.td)
+			plog.Debugf("addPeer: peer <%v> (td: %v) promoted best peer", newp.id, newp.td)
 		} else {
 			plog.Warnln("addPeer: no suitable peers found")
 		}
diff --git a/blockpool/peers_test.go b/blockpool/peers_test.go
index e53d7160b..99dd16ba1 100644
--- a/blockpool/peers_test.go
+++ b/blockpool/peers_test.go
@@ -3,8 +3,12 @@ package blockpool
 import (
 	"math/big"
 	"testing"
+	"time"
 
 	"github.com/ethereum/go-ethereum/blockpool/test"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
 )
 
 // the actual tests
@@ -115,6 +119,26 @@ func TestAddPeer(t *testing.T) {
 	}
 	peer0.waitBlocksRequests(3)
 
-	blockPool.Stop()
+	newblock := &types.Block{Td: common.Big3}
+	blockPool.chainEvents.Post(core.ChainHeadEvent{newblock})
+	time.Sleep(100 * time.Millisecond)
+	if blockPool.peers.best != nil {
+		t.Errorf("no peer should be ahead of self")
+	}
+	best = peer1.AddPeer()
+	if blockPool.peers.best != nil {
+		t.Errorf("still no peer should be ahead of self")
+	}
 
+	best = peer2.AddPeer()
+	if !best {
+		t.Errorf("peer2 (TD=4) not accepted as best")
+	}
+
+	blockPool.RemovePeer("peer2")
+	if blockPool.peers.best != nil {
+		t.Errorf("no peer should be ahead of self")
+	}
+
+	blockPool.Stop()
 }
diff --git a/eth/backend.go b/eth/backend.go
index afe314d74..141c6c605 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -195,7 +195,8 @@ func New(config *Config) (*Ethereum, error) {
 
 	hasBlock := eth.chainManager.HasBlock
 	insertChain := eth.chainManager.InsertChain
-	eth.blockPool = blockpool.New(hasBlock, insertChain, eth.pow.Verify)
+	td := eth.chainManager.Td()
+	eth.blockPool = blockpool.New(hasBlock, insertChain, eth.pow.Verify, eth.EventMux(), td)
 
 	netprv, err := config.nodeKey()
 	if err != nil {
diff --git a/eth/protocol_test.go b/eth/protocol_test.go
index 7620b3854..8ca6d1be6 100644
--- a/eth/protocol_test.go
+++ b/eth/protocol_test.go
@@ -41,17 +41,10 @@ type testChainManager struct {
 type testBlockPool struct {
 	addBlockHashes func(next func() (common.Hash, bool), peerId string)
 	addBlock       func(block *types.Block, peerId string) (err error)
-	addPeer        func(td *big.Int, currentBlock common.Hash, peerId string, requestHashes func(common.Hash) error, requestBlocks func([]common.Hash) error, peerError func(*errs.Error)) (best bool)
+	addPeer        func(td *big.Int, currentBlock common.Hash, peerId string, requestHashes func(common.Hash) error, requestBlocks func([]common.Hash) error, peerError func(*errs.Error)) (best bool, suspended bool)
 	removePeer     func(peerId string)
 }
 
-// func (self *testTxPool) GetTransactions() (txs []*types.Transaction) {
-// 	if self.getTransactions != nil {
-// 		txs = self.getTransactions()
-// 	}
-// 	return
-// }
-
 func (self *testTxPool) AddTransactions(txs []*types.Transaction) {
 	if self.addTransactions != nil {
 		self.addTransactions(txs)
@@ -93,9 +86,9 @@ func (self *testBlockPool) AddBlock(block *types.Block, peerId string) {
 	}
 }
 
-func (self *testBlockPool) AddPeer(td *big.Int, currentBlock common.Hash, peerId string, requestBlockHashes func(common.Hash) error, requestBlocks func([]common.Hash) error, peerError func(*errs.Error)) (best bool) {
+func (self *testBlockPool) AddPeer(td *big.Int, currentBlock common.Hash, peerId string, requestBlockHashes func(common.Hash) error, requestBlocks func([]common.Hash) error, peerError func(*errs.Error)) (best bool, suspended bool) {
 	if self.addPeer != nil {
-		best = self.addPeer(td, currentBlock, peerId, requestBlockHashes, requestBlocks, peerError)
+		best, suspended = self.addPeer(td, currentBlock, peerId, requestBlockHashes, requestBlocks, peerError)
 	}
 	return
 }