Add checks to regenerate fee estimator if an invalid state is

detected. Change default minimum registered blocks from 5 to 3.

Run goclean.sh

blockmanager.go

@@ -1160,7 +1160,16 @@ func (b *blockManager) handleNotifyMsg(notification *blockchain.Notification) {
 
 		// Register block with the fee estimator if enabled.
 		if b.server.feeEstimator != nil {
-			b.server.feeEstimator.RegisterBlock(block)
+			err := b.server.feeEstimator.RegisterBlock(block)
+
+			// If an error is somehow generated then the fee estimator
+			// has entered an invalid state. Since it doesn't know how
+			// to recover, create a new one.
+			if err != nil {
+				b.server.feeEstimator = mempool.NewFeeEstimator(
+					mempool.DefaultEstimateFeeMaxRollback,
+					mempool.DefaultEstimateFeeMinRegisteredBlocks)
+			}
 		}
 
 		if r := b.server.rpcServer; r != nil {

mempool/estimatefee.go

@@ -43,7 +43,7 @@ const (
 	// DefaultEstimateFeeMinRegisteredBlocks is the default minimum
 	// number of blocks which must be observed by the fee estimator before
 	// it will provide fee estimations.
-	DefaultEstimateFeeMinRegisteredBlocks = 5
+	DefaultEstimateFeeMinRegisteredBlocks = 3
 
 	bytePerKb = 1024
 
@@ -327,6 +327,14 @@ func (ef *FeeEstimator) RegisterBlock(block *btcutil.Block) error {
 	return nil
 }
 
+// LastKnownHeight returns the height of the last block which was registered.
+func (ef *FeeEstimator) LastKnownHeight() int32 {
+	ef.mtx.Lock()
+	defer ef.mtx.Unlock()
+
+	return ef.lastKnownHeight
+}
+
 // Rollback unregisters a recently registered block from the FeeEstimator.
 // This can be used to reverse the effect of an orphaned block on the fee
 // estimator. The maximum number of rollbacks allowed is given by
@@ -349,7 +357,7 @@ func (ef *FeeEstimator) Rollback(hash *chainhash.Hash) error {
 	}
 
 	if n > len(ef.dropped) {
-		return errors.New("No such block was recently registered.")
+		return errors.New("No such block was recently registered")
 	}
 
 	for i := 0; i < n; i++ {
@@ -392,7 +400,7 @@ func (ef *FeeEstimator) rollback() {
 		for {
 			if counter >= len(bin) {
 				// Panic, as we have entered an unrecoverable invalid state.
-				panic(errors.New("Illegal state: cannot rollback dropped transaction!"))
+				panic(errors.New("Illegal state: cannot rollback dropped transaction"))
 			}
 
 			prev := bin[counter]
@@ -546,16 +554,16 @@ func (ef *FeeEstimator) EstimateFee(numBlocks uint32) (BtcPerKilobyte, error) {
 	// If the number of registered blocks is below the minimum, return
 	// an error.
 	if ef.numBlocksRegistered < ef.minRegisteredBlocks {
-		return -1, errors.New("Not enough blocks have been observed.")
+		return -1, errors.New("Not enough blocks have been observed")
 	}
 
 	if numBlocks == 0 {
-		return -1, errors.New("Cannot confirm transaction in zero blocks.")
+		return -1, errors.New("Cannot confirm transaction in zero blocks")
 	}
 
 	if numBlocks > estimateFeeDepth {
 		return -1, fmt.Errorf(
-			"Can only estimate fees for up to %d blocks from now.",
+			"Can only estimate fees for up to %d blocks from now",
 			estimateFeeBinSize)
 	}
 

mempool/mempool.go

@@ -534,7 +534,7 @@ func (mp *TxPool) addTransaction(utxoView *blockchain.UtxoViewpoint, tx *btcutil
 	if mp.cfg.AddrIndex != nil {
 		mp.cfg.AddrIndex.AddUnconfirmedTx(tx, utxoView)
 	}
-	
+
 	// Record this tx for fee estimation if enabled.
 	if mp.cfg.FeeEstimator != nil {
 		mp.cfg.FeeEstimator.ObserveTransaction(txD)

rpcserver.go

@@ -822,7 +822,7 @@ func handleEstimateFee(s *rpcServer, cmd interface{}, closeChan <-chan struct{})
 	c := cmd.(*btcjson.EstimateFeeCmd)
 
 	if c.NumBlocks <= 0 {
-		return -1.0, errors.New("Parameter NumBlocks must be positive.")
+		return -1.0, errors.New("Parameter NumBlocks must be positive")
 	}
 
 	feeRate, err := s.server.feeEstimator.EstimateFee(uint32(c.NumBlocks))

server.go

@@ -2367,34 +2367,6 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 		sigCache:             txscript.NewSigCache(cfg.SigCacheMaxSize),
 	}
 
-	// Search for a FeeEstimator state in the database. If none can be found
-	// or if it cannot be loaded, create a new one.
-	db.Update(func(tx database.Tx) error {
-		metadata := tx.Metadata()
-		feeEstimationData := metadata.Get(mempool.EstimateFeeDatabaseKey)
-		if feeEstimationData != nil {
-			// delete it from the database so that we don't try to restore the
-			// same thing again somehow.
-			metadata.Delete(mempool.EstimateFeeDatabaseKey)
-
-			// If there is an error, log it and make a new fee estimator.
-			var err error
-			s.feeEstimator, err = mempool.RestoreFeeEstimator(feeEstimationData)
-
-			if err != nil {
-				peerLog.Errorf("Failed restore fee estimator %v", err)
-			}
-		}
-
-		return nil
-	})
-
-	if s.feeEstimator == nil {
-		s.feeEstimator = mempool.NewFeeEstimator(
-			mempool.DefaultEstimateFeeMaxRollback,
-			mempool.DefaultEstimateFeeMinRegisteredBlocks)
-	}
-
 	// Create the transaction and address indexes if needed.
 	//
 	// CAUTION: the txindex needs to be first in the indexes array because
@@ -2433,6 +2405,36 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 	}
 	s.blockManager = bm
 
+	// Search for a FeeEstimator state in the database. If none can be found
+	// or if it cannot be loaded, create a new one.
+	db.Update(func(tx database.Tx) error {
+		metadata := tx.Metadata()
+		feeEstimationData := metadata.Get(mempool.EstimateFeeDatabaseKey)
+		if feeEstimationData != nil {
+			// delete it from the database so that we don't try to restore the
+			// same thing again somehow.
+			metadata.Delete(mempool.EstimateFeeDatabaseKey)
+
+			// If there is an error, log it and make a new fee estimator.
+			var err error
+			s.feeEstimator, err = mempool.RestoreFeeEstimator(feeEstimationData)
+
+			if err != nil {
+				peerLog.Errorf("Failed restore fee estimator %v", err)
+			}
+		}
+
+		return nil
+	})
+
+	// If no feeEstimator has been found, or if the one that has been found
+	// is behind somehow, create a new one and start over.
+	if s.feeEstimator == nil || s.feeEstimator.LastKnownHeight() != s.blockManager.chain.BestSnapshot().Height {
+		s.feeEstimator = mempool.NewFeeEstimator(
+			mempool.DefaultEstimateFeeMaxRollback,
+			mempool.DefaultEstimateFeeMinRegisteredBlocks)
+	}
+
 	txC := mempool.Config{
 		Policy: mempool.Policy{
 			DisableRelayPriority: cfg.NoRelayPriority,
@@ -2451,9 +2453,9 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 		CalcSequenceLock: func(tx *btcutil.Tx, view *blockchain.UtxoViewpoint) (*blockchain.SequenceLock, error) {
 			return bm.chain.CalcSequenceLock(tx, view, true)
 		},
-		SigCache:         s.sigCache,
-		AddrIndex:        s.addrIndex,
-		FeeEstimator:     s.feeEstimator,
+		SigCache:     s.sigCache,
+		AddrIndex:    s.addrIndex,
+		FeeEstimator: s.feeEstimator,
 	}
 	s.txMemPool = mempool.New(&txC)