WIP5

batchbuilder/batchbuilder.go

@@ -54,7 +54,7 @@ func NewBatchBuilder(dbpath string, synchronizerStateDB *statedb.StateDB, batchN
 // copy of the rollup state from the Synchronizer at that `batchNum`, otherwise
 // it can just roll back the internal copy.
 func (bb *BatchBuilder) Reset(batchNum common.BatchNum, fromSynchronizer bool) error {
-	return bb.localStateDB.Reset(batchNum, fromSynchronizer)
+	return tracerr.Wrap(bb.localStateDB.Reset(batchNum, fromSynchronizer))
 }
 
 // BuildBatch takes the transactions and returns the common.ZKInputs of the next batch

common/batch.go

@@ -27,6 +27,7 @@ type Batch struct {
 	TotalFeesUSD       *float64             `meddler:"total_fees_usd"`
 }
 
+// NewEmptyBatch creates a new empty batch
 func NewEmptyBatch() *Batch {
 	return &Batch{
 		BatchNum:           0,

common/ethauction.go

@@ -32,10 +32,9 @@ type AuctionConstants struct {
 func (c *AuctionConstants) SlotNum(blockNum int64) int64 {
 	if blockNum >= c.GenesisBlockNum {
 		return (blockNum - c.GenesisBlockNum) / int64(c.BlocksPerSlot)
-	} else {
-		// This result will be negative
-		return (blockNum - c.GenesisBlockNum) / int64(c.BlocksPerSlot)
 	}
+	// This result will be negative
+	return (blockNum - c.GenesisBlockNum) / int64(c.BlocksPerSlot)
 }
 
 // SlotBlocks returns the first and the last block numbers included in that slot

config/config.go

@@ -56,7 +56,7 @@ type Coordinator struct {
 	// starting the pipeline when we reach a slot in which we can forge.
 	StartSlotBlocksDelay int64
 	// ScheduleBatchBlocksAheadCheck is the number of blocks ahead in which
-	// the forger address is checked to be allowed to forge (appart from
+	// the forger address is checked to be allowed to forge (apart from
 	// checking the next block), used to decide when to stop scheduling new
 	// batches (by stopping the pipeline).
 	// For example, if we are at block 10 and ScheduleBatchBlocksAheadCheck
@@ -66,7 +66,7 @@ type Coordinator struct {
 	// scheduling a batch and having it mined.
 	ScheduleBatchBlocksAheadCheck int64
 	// SendBatchBlocksMarginCheck is the number of margin blocks ahead in
-	// which the coordinator is also checked to be allowed to forge, appart
+	// which the coordinator is also checked to be allowed to forge, apart
 	// from the next block; used to decide when to stop sending batches to
 	// the smart contract.
 	// For example, if we are at block 10 and SendBatchBlocksMarginCheck is

coordinator/coordinator.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"math/big"
 	"os"
-	"strings"
 	"sync"
 	"time"
 
@@ -47,7 +46,7 @@ type Config struct {
 	// starting the pipeline when we reach a slot in which we can forge.
 	StartSlotBlocksDelay int64
 	// ScheduleBatchBlocksAheadCheck is the number of blocks ahead in which
-	// the forger address is checked to be allowed to forge (appart from
+	// the forger address is checked to be allowed to forge (apart from
 	// checking the next block), used to decide when to stop scheduling new
 	// batches (by stopping the pipeline).
 	// For example, if we are at block 10 and ScheduleBatchBlocksAheadCheck
@@ -57,7 +56,7 @@ type Config struct {
 	// scheduling a batch and having it mined.
 	ScheduleBatchBlocksAheadCheck int64
 	// SendBatchBlocksMarginCheck is the number of margin blocks ahead in
-	// which the coordinator is also checked to be allowed to forge, appart
+	// which the coordinator is also checked to be allowed to forge, apart
 	// from the next block; used to decide when to stop sending batches to
 	// the smart contract.
 	// For example, if we are at block 10 and SendBatchBlocksMarginCheck is
@@ -139,7 +138,8 @@ type Coordinator struct {
 	wg     sync.WaitGroup
 	cancel context.CancelFunc
 
-	pipeline *Pipeline
+	pipeline              *Pipeline
+	lastNonFailedBatchNum common.BatchNum
 
 	purger    *Purger
 	txManager *TxManager
@@ -233,7 +233,7 @@ func (c *Coordinator) BatchBuilder() *batchbuilder.BatchBuilder {
 func (c *Coordinator) newPipeline(ctx context.Context) (*Pipeline, error) {
 	c.pipelineNum++
 	return NewPipeline(ctx, c.cfg, c.pipelineNum, c.historyDB, c.l2DB, c.txSelector,
-		c.batchBuilder, c.purger, c.txManager, c.provers, &c.consts)
+		c.batchBuilder, c.purger, c, c.txManager, c.provers, &c.consts)
 }
 
 // MsgSyncBlock indicates an update to the Synchronizer stats
@@ -254,6 +254,9 @@ type MsgSyncReorg struct {
 // MsgStopPipeline indicates a signal to reset the pipeline
 type MsgStopPipeline struct {
 	Reason string
+	// FailedBatchNum indicates the first batchNum that faile in the
+	// pipeline.  If FailedBatchNum is 0, it should be ignored.
+	FailedBatchNum common.BatchNum
 }
 
 // SendMsg is a thread safe method to pass a message to the Coordinator
@@ -342,6 +345,9 @@ func (c *Coordinator) syncStats(ctx context.Context, stats *synchronizer.Stats)
 			log.Infow("Coordinator: forging state begin", "block",
 				stats.Eth.LastBlock.Num+1, "batch", stats.Sync.LastBatch.BatchNum)
 			batchNum := stats.Sync.LastBatch.BatchNum
+			if c.lastNonFailedBatchNum > batchNum {
+				batchNum = c.lastNonFailedBatchNum
+			}
 			var err error
 			if c.pipeline, err = c.newPipeline(ctx); err != nil {
 				return tracerr.Wrap(err)
@@ -367,19 +373,17 @@ func (c *Coordinator) syncStats(ctx context.Context, stats *synchronizer.Stats)
 		// 		return err
 		// 	}
 		// }
-		if c.purger.CanInvalidate(stats.Sync.LastBlock.Num, int64(stats.Sync.LastBatch.BatchNum)) {
-			if err := c.txSelector.Reset(stats.Sync.LastBatch.BatchNum); err != nil {
-				return tracerr.Wrap(err)
-			}
-		}
-		_, err := c.purger.InvalidateMaybe(c.l2DB, c.txSelector.LocalAccountsDB(),
-			stats.Sync.LastBlock.Num, int64(stats.Sync.LastBatch.BatchNum))
-		if err != nil {
+		// if c.purger.CanInvalidate(stats.Sync.LastBlock.Num, int64(stats.Sync.LastBatch.BatchNum)) {
+		// 	if err := c.txSelector.Reset(stats.Sync.LastBatch.BatchNum); err != nil {
+		// 		return tracerr.Wrap(err)
+		// 	}
+		// }
+		if _, err := c.purger.InvalidateMaybe(c.l2DB, c.txSelector.LocalAccountsDB(),
+			stats.Sync.LastBlock.Num, int64(stats.Sync.LastBatch.BatchNum)); err != nil {
 			return tracerr.Wrap(err)
 		}
-		_, err = c.purger.PurgeMaybe(c.l2DB, stats.Sync.LastBlock.Num,
-			int64(stats.Sync.LastBatch.BatchNum))
-		if err != nil {
+		if _, err := c.purger.PurgeMaybe(c.l2DB, stats.Sync.LastBlock.Num,
+			int64(stats.Sync.LastBatch.BatchNum)); err != nil {
 			return tracerr.Wrap(err)
 		}
 	}
@@ -419,24 +423,29 @@ func (c *Coordinator) handleReorg(ctx context.Context, msg *MsgSyncReorg) error
 			"sync.LastBatch.StateRoot", c.stats.Sync.LastBatch.StateRoot,
 			"pipelineFromBatch.StateRoot", c.pipelineFromBatch.StateRoot)
 		c.txManager.DiscardPipeline(ctx, c.pipelineNum)
-		if err := c.handleStopPipeline(ctx, "reorg"); err != nil {
+		if err := c.handleStopPipeline(ctx, "reorg", 0); err != nil {
 			return tracerr.Wrap(err)
 		}
 	}
 	return nil
 }
 
-func (c *Coordinator) handleStopPipeline(ctx context.Context, reason string) error {
+// handleStopPipeline handles stopping the pipeline.  If failedBatchNum is 0,
+// the next pipeline will start from the last state of the synchronizer,
+// otherwise, it will state from failedBatchNum-1.
+func (c *Coordinator) handleStopPipeline(ctx context.Context, reason string, failedBatchNum common.BatchNum) error {
+	batchNum := c.stats.Sync.LastBatch.BatchNum
+	if failedBatchNum != 0 {
+		batchNum = failedBatchNum - 1
+	}
 	if c.pipeline != nil {
 		c.pipeline.Stop(c.ctx)
 		c.pipeline = nil
 	}
-	if err := c.l2DB.Reorg(c.stats.Sync.LastBatch.BatchNum); err != nil {
+	if err := c.l2DB.Reorg(batchNum); err != nil {
 		return tracerr.Wrap(err)
 	}
-	if strings.Contains(reason, common.AuctionErrMsgCannotForge) { //nolint:staticcheck
-		// TODO: Check that we are in a slot in which we can't forge
-	}
+	c.lastNonFailedBatchNum = batchNum
 	return nil
 }
 
@@ -452,7 +461,7 @@ func (c *Coordinator) handleMsg(ctx context.Context, msg interface{}) error {
 		}
 	case MsgStopPipeline:
 		log.Infow("Coordinator received MsgStopPipeline", "reason", msg.Reason)
-		if err := c.handleStopPipeline(ctx, msg.Reason); err != nil {
+		if err := c.handleStopPipeline(ctx, msg.Reason, msg.FailedBatchNum); err != nil {
 			return tracerr.Wrap(fmt.Errorf("Coordinator.handleStopPipeline: %w", err))
 		}
 	default:

coordinator/pipeline.go

@@ -2,6 +2,7 @@ package coordinator
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 	"math/big"
 	"sync"
@@ -41,10 +42,13 @@ type Pipeline struct {
 	// batchNum                     common.BatchNum
 	// lastScheduledL1BatchBlockNum int64
 	// lastForgeL1TxsNum            int64
-	started bool
+	started       bool
+	rw            sync.RWMutex
+	errAtBatchNum common.BatchNum
 
 	proversPool  *ProversPool
 	provers      []prover.Client
+	coord        *Coordinator
 	txManager    *TxManager
 	historyDB    *historydb.HistoryDB
 	l2DB         *l2db.L2DB
@@ -61,6 +65,18 @@ type Pipeline struct {
 	cancel context.CancelFunc
 }
 
+func (p *Pipeline) setErrAtBatchNum(batchNum common.BatchNum) {
+	p.rw.Lock()
+	defer p.rw.Unlock()
+	p.errAtBatchNum = batchNum
+}
+
+func (p *Pipeline) getErrAtBatchNum() common.BatchNum {
+	p.rw.RLock()
+	defer p.rw.RUnlock()
+	return p.errAtBatchNum
+}
+
 // NewPipeline creates a new Pipeline
 func NewPipeline(ctx context.Context,
 	cfg Config,
@@ -70,6 +86,7 @@ func NewPipeline(ctx context.Context,
 	txSelector *txselector.TxSelector,
 	batchBuilder *batchbuilder.BatchBuilder,
 	purger *Purger,
+	coord *Coordinator,
 	txManager *TxManager,
 	provers []prover.Client,
 	scConsts *synchronizer.SCConsts,
@@ -97,6 +114,7 @@ func NewPipeline(ctx context.Context,
 		provers:      provers,
 		proversPool:  proversPool,
 		purger:       purger,
+		coord:        coord,
 		txManager:    txManager,
 		consts:       *scConsts,
 		statsVarsCh:  make(chan statsVars, queueLen),
@@ -122,14 +140,54 @@ func (p *Pipeline) reset(batchNum common.BatchNum,
 	p.stats = *stats
 	p.vars = *vars
 
-	err := p.txSelector.Reset(p.state.batchNum)
+	// Reset the StateDB in TxSelector and BatchBuilder from the
+	// synchronizer only if the checkpoint we reset from either:
+	// a. Doesn't exist in the TxSelector/BatchBuilder
+	// b. The batch has already been synced by the synchronizer and has a
+	//    different MTRoot than the BatchBuilder
+	// Otherwise, reset from the local checkpoint.
+
+	// First attempt to reset from local checkpoint if such checkpoint exists
+	existsTxSelector, err := p.txSelector.LocalAccountsDB().CheckpointExists(p.state.batchNum)
 	if err != nil {
 		return tracerr.Wrap(err)
 	}
-	err = p.batchBuilder.Reset(p.state.batchNum, true)
+	fromSynchronizerTxSelector := !existsTxSelector
+	if err := p.txSelector.Reset(p.state.batchNum, fromSynchronizerTxSelector); err != nil {
+		return tracerr.Wrap(err)
+	}
+	existsBatchBuilder, err := p.batchBuilder.LocalStateDB().CheckpointExists(p.state.batchNum)
 	if err != nil {
 		return tracerr.Wrap(err)
 	}
+	fromSynchronizerBatchBuilder := !existsBatchBuilder
+	if err := p.batchBuilder.Reset(p.state.batchNum, fromSynchronizerBatchBuilder); err != nil {
+		return tracerr.Wrap(err)
+	}
+
+	// After reset, check that if the batch exists in the historyDB, the
+	// stateRoot matches with the local one, if not, force a reset from
+	// synchronizer
+	batch, err := p.historyDB.GetBatch(p.state.batchNum)
+	if tracerr.Unwrap(err) == sql.ErrNoRows {
+		// nothing to do
+	} else if err != nil {
+		return tracerr.Wrap(err)
+	} else {
+		localStateRoot := p.batchBuilder.LocalStateDB().MT.Root().BigInt()
+		if batch.StateRoot.Cmp(localStateRoot) != 0 {
+			log.Debugw("localStateRoot (%v) != historyDB stateRoot (%v).  "+
+				"Forcing reset from Synchronizer", localStateRoot, batch.StateRoot)
+			// StateRoot from synchronizer doesn't match StateRoot
+			// from batchBuilder, force a reset from synchronizer
+			if err := p.txSelector.Reset(p.state.batchNum, true); err != nil {
+				return tracerr.Wrap(err)
+			}
+			if err := p.batchBuilder.Reset(p.state.batchNum, true); err != nil {
+				return tracerr.Wrap(err)
+			}
+		}
+	}
 	return nil
 }
 
@@ -203,14 +261,31 @@ func (p *Pipeline) Start(batchNum common.BatchNum,
 				p.stats = statsVars.Stats
 				p.syncSCVars(statsVars.Vars)
 			case <-time.After(waitDuration):
+				// Once errAtBatchNum != 0, we stop forging
+				// batches because there's been an error and we
+				// wait for the pipeline to be stopped.
+				if p.getErrAtBatchNum() != 0 {
+					waitDuration = p.cfg.ForgeRetryInterval
+					continue
+				}
 				batchNum = p.state.batchNum + 1
 				batchInfo, err := p.handleForgeBatch(p.ctx, batchNum)
 				if p.ctx.Err() != nil {
 					continue
+				} else if tracerr.Unwrap(err) == errLastL1BatchNotSynced {
+					waitDuration = p.cfg.ForgeRetryInterval
+					continue
 				} else if err != nil {
-					waitDuration = p.cfg.SyncRetryInterval
+					p.setErrAtBatchNum(batchNum)
+					waitDuration = p.cfg.ForgeRetryInterval
+					p.coord.SendMsg(p.ctx, MsgStopPipeline{
+						Reason: fmt.Sprintf(
+							"Pipeline.handleForgBatch: %v", err),
+						FailedBatchNum: batchNum,
+					})
 					continue
 				}
+
 				p.state.batchNum = batchNum
 				select {
 				case batchChSentServerProof <- batchInfo:
@@ -229,16 +304,28 @@ func (p *Pipeline) Start(batchNum common.BatchNum,
 				p.wg.Done()
 				return
 			case batchInfo := <-batchChSentServerProof:
+				// Once errAtBatchNum != 0, we stop forging
+				// batches because there's been an error and we
+				// wait for the pipeline to be stopped.
+				if p.getErrAtBatchNum() != 0 {
+					continue
+				}
 				err := p.waitServerProof(p.ctx, batchInfo)
-				// We are done with this serverProof, add it back to the pool
-				p.proversPool.Add(p.ctx, batchInfo.ServerProof)
 				batchInfo.ServerProof = nil
 				if p.ctx.Err() != nil {
 					continue
 				} else if err != nil {
 					log.Errorw("waitServerProof", "err", err)
+					p.setErrAtBatchNum(batchInfo.BatchNum)
+					p.coord.SendMsg(p.ctx, MsgStopPipeline{
+						Reason: fmt.Sprintf(
+							"Pipeline.waitServerProof: %v", err),
+						FailedBatchNum: batchInfo.BatchNum,
+					})
 					continue
 				}
+				// We are done with this serverProof, add it back to the pool
+				p.proversPool.Add(p.ctx, batchInfo.ServerProof)
 				p.txManager.AddBatch(p.ctx, batchInfo)
 			}
 		}
@@ -304,17 +391,14 @@ func (p *Pipeline) forgeBatch(batchNum common.BatchNum) (batchInfo *BatchInfo, e
 	var auths [][]byte
 	var coordIdxs []common.Idx
 
+	// TODO: If there are no txs and we are behind the timeout, skip
+	// forging a batch and return a particular error that can be handleded
+	// in the loop where handleForgeBatch is called to retry after an
+	// interval
+
 	// 1. Decide if we forge L2Tx or L1+L2Tx
 	if p.shouldL1L2Batch(batchInfo) {
 		batchInfo.L1Batch = true
-		defer func() {
-			// If there's no error, update the parameters related
-			// to the last L1Batch forged
-			if err == nil {
-				p.state.lastScheduledL1BatchBlockNum = p.stats.Eth.LastBlock.Num + 1
-				p.state.lastForgeL1TxsNum++
-			}
-		}()
 		if p.state.lastForgeL1TxsNum != p.stats.Sync.LastForgeL1TxsNum {
 			return nil, tracerr.Wrap(errLastL1BatchNotSynced)
 		}
@@ -328,6 +412,9 @@ func (p *Pipeline) forgeBatch(batchNum common.BatchNum) (batchInfo *BatchInfo, e
 		if err != nil {
 			return nil, tracerr.Wrap(err)
 		}
+
+		p.state.lastScheduledL1BatchBlockNum = p.stats.Eth.LastBlock.Num + 1
+		p.state.lastForgeL1TxsNum++
 	} else {
 		// 2b: only L2 txs
 		coordIdxs, auths, l1CoordTxs, poolL2Txs, discardedL2Txs, err =

coordinator/txmanager.go

@@ -183,7 +183,8 @@ func (t *TxManager) shouldSendRollupForgeBatch(batchInfo *BatchInfo) error {
 func addPerc(v *big.Int, p int64) *big.Int {
 	r := new(big.Int).Set(v)
 	r.Mul(r, big.NewInt(p))
-	r.Div(r, big.NewInt(100))
+	// nolint reason: to calculate percetnages we divide by 100
+	r.Div(r, big.NewInt(100)) //nolit:gomnd
 	return r.Add(v, r)
 }
 
@@ -352,12 +353,14 @@ func (t *TxManager) handleReceipt(ctx context.Context, batchInfo *BatchInfo) (*i
 // TODO:
 // - After sending a message: CancelPipeline, stop all consecutive pending Batches (transactions)
 
+// Queue of BatchInfos
 type Queue struct {
 	list []*BatchInfo
 	// nonceByBatchNum map[common.BatchNum]uint64
 	next int
 }
 
+// NewQueue returns a new queue
 func NewQueue() Queue {
 	return Queue{
 		list: make([]*BatchInfo, 0),
@@ -366,10 +369,12 @@ func NewQueue() Queue {
 	}
 }
 
+// Len is the length of the queue
 func (q *Queue) Len() int {
 	return len(q.list)
 }
 
+// At returns the BatchInfo at position (or nil if position is out of bounds)
 func (q *Queue) At(position int) *BatchInfo {
 	if position >= len(q.list) {
 		return nil
@@ -377,6 +382,7 @@ func (q *Queue) At(position int) *BatchInfo {
 	return q.list[position]
 }
 
+// Next returns the next BatchInfo (or nil if queue is empty)
 func (q *Queue) Next() (int, *BatchInfo) {
 	if len(q.list) == 0 {
 		return 0, nil
@@ -385,6 +391,7 @@ func (q *Queue) Next() (int, *BatchInfo) {
 	return q.next, q.list[q.next]
 }
 
+// Remove removes the BatchInfo at position
 func (q *Queue) Remove(position int) {
 	// batchInfo := q.list[position]
 	// delete(q.nonceByBatchNum, batchInfo.BatchNum)
@@ -396,6 +403,7 @@ func (q *Queue) Remove(position int) {
 	}
 }
 
+// Push adds a new BatchInfo
 func (q *Queue) Push(batchInfo *BatchInfo) {
 	q.list = append(q.list, batchInfo)
 	// q.nonceByBatchNum[batchInfo.BatchNum] = batchInfo.EthTx.Nonce()
@@ -517,8 +525,8 @@ func (t *TxManager) Run(ctx context.Context) {
 						Reason: fmt.Sprintf("forgeBatch resend: %v", err)})
 					continue
 				}
-
 			}
+
 			if confirm != nil && *confirm >= t.cfg.ConfirmBlocks {
 				log.Debugw("TxManager: forgeBatch tx confirmed",
 					"tx", batchInfo.EthTx.Hash(), "batch", batchInfo.BatchNum)

db/historydb/historydb.go

@@ -164,6 +164,19 @@ func (hdb *HistoryDB) addBatches(d meddler.DB, batches []common.Batch) error {
 	return nil
 }
 
+// GetBatch returns the batch with the given batchNum
+func (hdb *HistoryDB) GetBatch(batchNum common.BatchNum) (*common.Batch, error) {
+	var batch common.Batch
+	err := meddler.QueryRow(
+		hdb.db, &batch, `SELECT batch.batch_num, batch.eth_block_num, batch.forger_addr,
+		batch.fees_collected, batch.fee_idxs_coordinator, batch.state_root,
+		batch.num_accounts, batch.last_idx, batch.exit_root, batch.forge_l1_txs_num,
+		batch.slot_num, batch.total_fees_usd FROM batch WHERE batch_num = $1;`,
+		batchNum,
+	)
+	return &batch, err
+}
+
 // GetAllBatches retrieve all batches from the DB
 func (hdb *HistoryDB) GetAllBatches() ([]common.Batch, error) {
 	var batches []*common.Batch
@@ -208,7 +221,7 @@ func (hdb *HistoryDB) GetLastBatchNum() (common.BatchNum, error) {
 	return batchNum, tracerr.Wrap(row.Scan(&batchNum))
 }
 
-// GetLastBatchreturns the last forged batch
+// GetLastBatch returns the last forged batch
 func (hdb *HistoryDB) GetLastBatch() (*common.Batch, error) {
 	var batch common.Batch
 	err := meddler.QueryRow(

db/historydb/historydb_test.go

@@ -215,6 +215,12 @@ func TestBatches(t *testing.T) {
 	fetchedLastL1BatchBlockNum, err := historyDB.GetLastL1BatchBlockNum()
 	assert.NoError(t, err)
 	assert.Equal(t, lastL1BatchBlockNum, fetchedLastL1BatchBlockNum)
+	// Test GetBatch
+	fetchedBatch, err := historyDB.GetBatch(1)
+	require.NoError(t, err)
+	assert.Equal(t, &batches[0], fetchedBatch)
+	_, err = historyDB.GetBatch(common.BatchNum(len(batches) + 1))
+	assert.Equal(t, sql.ErrNoRows, tracerr.Unwrap(err))
 }
 
 func TestBids(t *testing.T) {

db/kvdb/kvdb.go

@@ -425,12 +425,13 @@ func (k *KVDB) MakeCheckpoint() error {
 	}
 
 	// if checkpoint BatchNum already exist in disk, delete it
-	if _, err := os.Stat(checkpointPath); !os.IsNotExist(err) {
+	if _, err := os.Stat(checkpointPath); os.IsNotExist(err) {
+	} else if err != nil {
+		return tracerr.Wrap(err)
+	} else {
 		if err := os.RemoveAll(checkpointPath); err != nil {
 			return tracerr.Wrap(err)
 		}
-	} else if err != nil && !os.IsNotExist(err) {
-		return tracerr.Wrap(err)
 	}
 
 	// execute Checkpoint
@@ -451,12 +452,25 @@ func (k *KVDB) MakeCheckpoint() error {
 	return nil
 }
 
+// CheckpointExists returns true if the checkpoint exists
+func (k *KVDB) CheckpointExists(batchNum common.BatchNum) (bool, error) {
+	source := path.Join(k.cfg.Path, fmt.Sprintf("%s%d", PathBatchNum, batchNum))
+	if _, err := os.Stat(source); os.IsNotExist(err) {
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
 // DeleteCheckpoint removes if exist the checkpoint of the given batchNum
 func (k *KVDB) DeleteCheckpoint(batchNum common.BatchNum) error {
 	checkpointPath := path.Join(k.cfg.Path, fmt.Sprintf("%s%d", PathBatchNum, batchNum))
 
 	if _, err := os.Stat(checkpointPath); os.IsNotExist(err) {
 		return tracerr.Wrap(fmt.Errorf("Checkpoint with batchNum %d does not exist in DB", batchNum))
+	} else if err != nil {
+		return tracerr.Wrap(err)
 	}
 
 	return os.RemoveAll(checkpointPath)
@@ -520,6 +534,8 @@ func (k *KVDB) MakeCheckpointFromTo(fromBatchNum common.BatchNum, dest string) e
 	if _, err := os.Stat(source); os.IsNotExist(err) {
 		// if kvdb does not have checkpoint at batchNum, return err
 		return tracerr.Wrap(fmt.Errorf("Checkpoint \"%v\" does not exist", source))
+	} else if err != nil {
+		return tracerr.Wrap(err)
 	}
 	// By locking we allow calling MakeCheckpointFromTo from multiple
 	// places at the same time for the same stateDB.  This allows the
@@ -533,12 +549,13 @@ func (k *KVDB) MakeCheckpointFromTo(fromBatchNum common.BatchNum, dest string) e
 
 func pebbleMakeCheckpoint(source, dest string) error {
 	// Remove dest folder (if it exists) before doing the checkpoint
-	if _, err := os.Stat(dest); !os.IsNotExist(err) {
+	if _, err := os.Stat(dest); os.IsNotExist(err) {
+	} else if err != nil {
+		return tracerr.Wrap(err)
+	} else {
 		if err := os.RemoveAll(dest); err != nil {
 			return tracerr.Wrap(err)
 		}
-	} else if err != nil && !os.IsNotExist(err) {
-		return tracerr.Wrap(err)
 	}
 
 	sto, err := pebble.NewPebbleStorage(source, false)

db/statedb/statedb.go

@@ -498,11 +498,17 @@ func NewLocalStateDB(cfg Config, synchronizerDB *StateDB) (*LocalStateDB, error)
 	}, nil
 }
 
+// CheckpointExists returns true if the checkpoint exists
+func (l *LocalStateDB) CheckpointExists(batchNum common.BatchNum) (bool, error) {
+	return l.db.CheckpointExists(batchNum)
+}
+
 // Reset performs a reset in the LocaStateDB. If fromSynchronizer is true, it
 // gets the state from LocalStateDB.synchronizerStateDB for the given batchNum.
 // If fromSynchronizer is false, get the state from LocalStateDB checkpoints.
 func (l *LocalStateDB) Reset(batchNum common.BatchNum, fromSynchronizer bool) error {
 	if fromSynchronizer {
+		log.Debugw("Making StateDB ResetFromSynchronizer", "batch", batchNum, "type", l.cfg.Type)
 		if err := l.db.ResetFromSynchronizer(batchNum, l.synchronizerStateDB.db); err != nil {
 			return tracerr.Wrap(err)
 		}

txselector/txselector.go

@@ -89,12 +89,8 @@ func (txsel *TxSelector) LocalAccountsDB() *statedb.LocalStateDB {
 
 // Reset tells the TxSelector to get it's internal AccountsDB
 // from the required `batchNum`
-func (txsel *TxSelector) Reset(batchNum common.BatchNum) error {
-	err := txsel.localAccountsDB.Reset(batchNum, true)
-	if err != nil {
-		return tracerr.Wrap(err)
-	}
-	return nil
+func (txsel *TxSelector) Reset(batchNum common.BatchNum, fromSynchronizer bool) error {
+	return tracerr.Wrap(txsel.localAccountsDB.Reset(batchNum, fromSynchronizer))
 }
 
 func (txsel *TxSelector) getCoordIdx(tokenID common.TokenID) (common.Idx, error) {