Add checks to regenerate fee estimator if an invalid state is detecte…

…d. Change default minimum registered blocks from 5 to 3.

blockmanager.go

@@ -1158,7 +1158,16 @@ 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

server.go

@@ -2329,34 +2329,6 @@ 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
@@ -2395,6 +2367,36 @@ 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,