Merge pull request #2326 from OffchainLabs/poster-nonce-switch

Fix off-by-one in data poster nonce check

arbnode/dataposter/data_poster.go

@@ -851,31 +851,31 @@ func (p *DataPoster) sendTx(ctx context.Context, prevTx *storage.QueuedTransacti
 	// different type with a lower nonce.
 	// If we decide not to send this tx yet, just leave it queued and with Sent set to false.
 	// The resending/repricing loop in DataPoster.Start will keep trying.
-	if !newTx.Sent && newTx.FullTx.Nonce() > 0 {
+	previouslySent := newTx.Sent || (prevTx != nil && prevTx.Sent) // if we've previously sent this nonce
+	if !previouslySent && newTx.FullTx.Nonce() > 0 {
 		precedingTx, err := p.queue.Get(ctx, arbmath.SaturatingUSub(newTx.FullTx.Nonce(), 1))
 		if err != nil {
 			return fmt.Errorf("couldn't get preceding tx in DataPoster to check if should send tx with nonce %d: %w", newTx.FullTx.Nonce(), err)
 		}
 		if precedingTx != nil { // precedingTx == nil -> the actual preceding tx was already confirmed
-			var latestBlockNumber, prevBlockNumber, reorgResistantNonce uint64
+			var latestBlockNumber, prevBlockNumber, reorgResistantTxCount uint64
 			if precedingTx.FullTx.Type() != newTx.FullTx.Type() || !precedingTx.Sent {
 				latestBlockNumber, err = p.client.BlockNumber(ctx)
 				if err != nil {
 					return fmt.Errorf("couldn't get block number in DataPoster to check if should send tx with nonce %d: %w", newTx.FullTx.Nonce(), err)
 				}
 				prevBlockNumber = arbmath.SaturatingUSub(latestBlockNumber, 1)
-				reorgResistantNonce, err = p.client.NonceAt(ctx, p.Sender(), new(big.Int).SetUint64(prevBlockNumber))
+				reorgResistantTxCount, err = p.client.NonceAt(ctx, p.Sender(), new(big.Int).SetUint64(prevBlockNumber))
 				if err != nil {
 					return fmt.Errorf("couldn't determine reorg resistant nonce in DataPoster to check if should send tx with nonce %d: %w", newTx.FullTx.Nonce(), err)
 				}
 
-				if precedingTx.FullTx.Nonce() > reorgResistantNonce {
-					log.Info("DataPoster is avoiding creating a mempool nonce gap (the tx remains queued and will be retried)", "nonce", newTx.FullTx.Nonce(), "prevType", precedingTx.FullTx.Type(), "type", newTx.FullTx.Type(), "prevSent", precedingTx.Sent)
+				if newTx.FullTx.Nonce() > reorgResistantTxCount {
+					log.Info("DataPoster is avoiding creating a mempool nonce gap (the tx remains queued and will be retried)", "nonce", newTx.FullTx.Nonce(), "prevType", precedingTx.FullTx.Type(), "type", newTx.FullTx.Type(), "prevSent", precedingTx.Sent, "latestBlockNumber", latestBlockNumber, "prevBlockNumber", prevBlockNumber, "reorgResistantTxCount", reorgResistantTxCount)
 					return nil
 				}
-			} else {
-				log.Info("DataPoster will send previously unsent batch tx", "nonce", newTx.FullTx.Nonce(), "prevType", precedingTx.FullTx.Type(), "type", newTx.FullTx.Type(), "prevSent", precedingTx.Sent, "latestBlockNumber", latestBlockNumber, "prevBlockNumber", prevBlockNumber, "reorgResistantNonce", reorgResistantNonce)
 			}
+			log.Debug("DataPoster will send previously unsent batch tx", "nonce", newTx.FullTx.Nonce(), "prevType", precedingTx.FullTx.Type(), "type", newTx.FullTx.Type(), "prevSent", precedingTx.Sent, "latestBlockNumber", latestBlockNumber, "prevBlockNumber", prevBlockNumber, "reorgResistantTxCount", reorgResistantTxCount)
 		}
 	}