Fix eth events query and sync inconsistent state

- kvdb
	- Fix path in Last when doing `setNew`
	- Only close if db != nil, and after closing, always set db to nil
		- This will avoid a panic in the case where the db is closed but
		  there's an error soon after, and a future call tries to close
		  again.  This is because pebble.Close() will panic if the db is
		  already closed.
	- Avoid calling pebble methods when a the Storage interface already
	  implements that method (like Close).
- statedb
	- In test, avoid calling KVDB method if the same method is available for
	  the StateDB (like MakeCheckpoint, CurrentBatch).
- eth
	- In *EventByBlock methods, take blockHash as input argument and use it
	  when querying the event logs.  Previously the blockHash was only taken
	  from the logs results *only if* there was any log.  This caused the
	  following issue: if there was no logs, it was not possible to know if
	  the result was from the expected block or an uncle block!  By querying
	  logs by blockHash we make sure that even if there are no logs, they
	  are from the right block.
	  	- Note that now the function can either be called with a
		  blockNum or blockHash, but not both at the same time.
- sync
	- If there's an error during call to Sync call resetState, which
	  internally resets the stateDB to avoid stale checkpoints (and a
	  corresponding invalid increase in the StateDB batchNum).
	- During a Sync, after very batch processed, make sure that the StateDB
	  currentBatch corresponds to the batchNum in the smart contract
	  log/event.

eth/auction.go

@@ -254,7 +254,7 @@ type AuctionInterface interface {
 	//
 
 	AuctionConstants() (*common.AuctionConstants, error)
-	AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *ethCommon.Hash, error)
+	AuctionEventsByBlock(blockNum int64, blockHash *ethCommon.Hash) (*AuctionEvents, error)
 	AuctionEventInit() (*AuctionEventInitialize, int64, error)
 }
 
@@ -797,15 +797,22 @@ func (c *AuctionClient) AuctionEventInit() (*AuctionEventInitialize, int64, erro
 }
 
 // AuctionEventsByBlock returns the events in a block that happened in the
-// Auction Smart Contract and the blockHash where the eents happened.  If there
-// are no events in that block, blockHash is nil.
-func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *ethCommon.Hash, error) {
+// Auction Smart Contract.
+// To query by blockNum, set blockNum >= 0 and blockHash == nil.
+// To query by blockHash, set blockNum == -1 and blockHash != nil.
+// If there are no events in that block the result is nil.
+func (c *AuctionClient) AuctionEventsByBlock(blockNum int64,
+	blockHash *ethCommon.Hash) (*AuctionEvents, error) {
 	var auctionEvents AuctionEvents
-	var blockHash *ethCommon.Hash
 
+	var blockNumBigInt *big.Int
+	if blockNum >= 0 {
+		blockNumBigInt = big.NewInt(blockNum)
+	}
 	query := ethereum.FilterQuery{
-		FromBlock: big.NewInt(blockNum),
-		ToBlock:   big.NewInt(blockNum),
+		BlockHash: blockHash,
+		FromBlock: blockNumBigInt,
+		ToBlock:   blockNumBigInt,
 		Addresses: []ethCommon.Address{
 			c.address,
 		},
@@ -814,15 +821,16 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 
 	logs, err := c.client.client.FilterLogs(context.TODO(), query)
 	if err != nil {
-		return nil, nil, tracerr.Wrap(err)
+		return nil, tracerr.Wrap(err)
 	}
-	if len(logs) > 0 {
-		blockHash = &logs[0].BlockHash
+	if len(logs) == 0 {
+		return nil, nil
 	}
+
 	for _, vLog := range logs {
-		if vLog.BlockHash != *blockHash {
+		if blockHash != nil && vLog.BlockHash != *blockHash {
 			log.Errorw("Block hash mismatch", "expected", blockHash.String(), "got", vLog.BlockHash.String())
-			return nil, nil, tracerr.Wrap(ErrBlockHashMismatchEvent)
+			return nil, tracerr.Wrap(ErrBlockHashMismatchEvent)
 		}
 		switch vLog.Topics[0] {
 		case logAuctionNewBid:
@@ -833,7 +841,7 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 			}
 			var newBid AuctionEventNewBid
 			if err := c.contractAbi.UnpackIntoInterface(&auxNewBid, "NewBid", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			newBid.BidAmount = auxNewBid.BidAmount
 			newBid.Slot = new(big.Int).SetBytes(vLog.Topics[1][:]).Int64()
@@ -842,19 +850,19 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 		case logAuctionNewSlotDeadline:
 			var newSlotDeadline AuctionEventNewSlotDeadline
 			if err := c.contractAbi.UnpackIntoInterface(&newSlotDeadline, "NewSlotDeadline", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			auctionEvents.NewSlotDeadline = append(auctionEvents.NewSlotDeadline, newSlotDeadline)
 		case logAuctionNewClosedAuctionSlots:
 			var newClosedAuctionSlots AuctionEventNewClosedAuctionSlots
 			if err := c.contractAbi.UnpackIntoInterface(&newClosedAuctionSlots, "NewClosedAuctionSlots", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			auctionEvents.NewClosedAuctionSlots = append(auctionEvents.NewClosedAuctionSlots, newClosedAuctionSlots)
 		case logAuctionNewOutbidding:
 			var newOutbidding AuctionEventNewOutbidding
 			if err := c.contractAbi.UnpackIntoInterface(&newOutbidding, "NewOutbidding", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			auctionEvents.NewOutbidding = append(auctionEvents.NewOutbidding, newOutbidding)
 		case logAuctionNewDonationAddress:
@@ -864,26 +872,26 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 		case logAuctionNewBootCoordinator:
 			var newBootCoordinator AuctionEventNewBootCoordinator
 			if err := c.contractAbi.UnpackIntoInterface(&newBootCoordinator, "NewBootCoordinator", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			newBootCoordinator.NewBootCoordinator = ethCommon.BytesToAddress(vLog.Topics[1].Bytes())
 			auctionEvents.NewBootCoordinator = append(auctionEvents.NewBootCoordinator, newBootCoordinator)
 		case logAuctionNewOpenAuctionSlots:
 			var newOpenAuctionSlots AuctionEventNewOpenAuctionSlots
 			if err := c.contractAbi.UnpackIntoInterface(&newOpenAuctionSlots, "NewOpenAuctionSlots", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			auctionEvents.NewOpenAuctionSlots = append(auctionEvents.NewOpenAuctionSlots, newOpenAuctionSlots)
 		case logAuctionNewAllocationRatio:
 			var newAllocationRatio AuctionEventNewAllocationRatio
 			if err := c.contractAbi.UnpackIntoInterface(&newAllocationRatio, "NewAllocationRatio", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			auctionEvents.NewAllocationRatio = append(auctionEvents.NewAllocationRatio, newAllocationRatio)
 		case logAuctionSetCoordinator:
 			var setCoordinator AuctionEventSetCoordinator
 			if err := c.contractAbi.UnpackIntoInterface(&setCoordinator, "SetCoordinator", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			setCoordinator.BidderAddress = ethCommon.BytesToAddress(vLog.Topics[1].Bytes())
 			setCoordinator.ForgerAddress = ethCommon.BytesToAddress(vLog.Topics[2].Bytes())
@@ -891,7 +899,7 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 		case logAuctionNewForgeAllocated:
 			var newForgeAllocated AuctionEventNewForgeAllocated
 			if err := c.contractAbi.UnpackIntoInterface(&newForgeAllocated, "NewForgeAllocated", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			newForgeAllocated.Bidder = ethCommon.BytesToAddress(vLog.Topics[1].Bytes())
 			newForgeAllocated.Forger = ethCommon.BytesToAddress(vLog.Topics[2].Bytes())
@@ -904,7 +912,7 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 			}
 			var newDefaultSlotSetBid AuctionEventNewDefaultSlotSetBid
 			if err := c.contractAbi.UnpackIntoInterface(&auxNewDefaultSlotSetBid, "NewDefaultSlotSetBid", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			newDefaultSlotSetBid.NewInitialMinBid = auxNewDefaultSlotSetBid.NewInitialMinBid
 			newDefaultSlotSetBid.SlotSet = auxNewDefaultSlotSetBid.SlotSet.Int64()
@@ -917,11 +925,11 @@ func (c *AuctionClient) AuctionEventsByBlock(blockNum int64) (*AuctionEvents, *e
 		case logAuctionHEZClaimed:
 			var HEZClaimed AuctionEventHEZClaimed
 			if err := c.contractAbi.UnpackIntoInterface(&HEZClaimed, "HEZClaimed", vLog.Data); err != nil {
-				return nil, nil, tracerr.Wrap(err)
+				return nil, tracerr.Wrap(err)
 			}
 			HEZClaimed.Owner = ethCommon.BytesToAddress(vLog.Topics[1].Bytes())
 			auctionEvents.HEZClaimed = append(auctionEvents.HEZClaimed, HEZClaimed)
 		}
 	}
-	return &auctionEvents, blockHash, nil
+	return &auctionEvents, nil
 }