Add discard cli to discard synced blocks

The command is useful in case the synchronizer reaches an invalid state and you
want to roll back a few blocks and try again (maybe with some fixes in the
code).

cli/node/README.md

@@ -117,7 +117,16 @@ Generate a new BabyJubJub key pair:
 ./node --mode coord --cfg cfg.buidler.toml genbjj
 ```
 
-Wipe the entier SQL database (this will destroy all synchronized and pool data):
+Wipe the entier SQL database (this will destroy all synchronized and pool
+data):
 ```
 ./node --mode coord --cfg cfg.buidler.toml wipesql
 ```
+
+Discard all synchronized blocks and associated state up to a given block
+number.  This command is useful in case the synchronizer reaches an invalid
+state and you want to roll back a few blocks and try again (maybe with some
+fixes in the code).
+```
+./node --mode coord --cfg cfg.buidler.toml discard --block 8061330
+```

cli/node/cfg.buidler.toml

@@ -53,6 +53,8 @@ SendBatchBlocksMarginCheck = 1
 ProofServerPollInterval = "1s"
 ForgeRetryInterval = "500ms"
 SyncRetryInterval = "1s"
+ForgeDelay = "10s"
+ForgeNoTxsDelay = "0s"
 
 [Coordinator.FeeAccount]
 Address = "0x56232B1c5B10038125Bc7345664B4AFD745bcF8E"
@@ -83,16 +85,13 @@ MaxTx = 512
 NLevels = 32
 
 [Coordinator.EthClient]
-ReceiptTimeout      = "60s"
-ReceiptLoopInterval = "500ms"
 CheckLoopInterval = "500ms"
 Attempts = 4
 AttemptsDelay = "500ms"
 TxResendTimeout = "2m"
 NoReuseNonce = false
-CallGasLimit = 300000
-GasPriceDiv = 100
 MaxGasPrice = "5000000000"
+GasPriceIncPerc = 10
 
 [Coordinator.EthClient.Keystore]
 Path = "/tmp/iden3-test/hermez/ethkeystore"

cli/node/main.go

@@ -11,6 +11,8 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/hermeznetwork/hermez-node/config"
 	dbUtils "github.com/hermeznetwork/hermez-node/db"
+	"github.com/hermeznetwork/hermez-node/db/historydb"
+	"github.com/hermeznetwork/hermez-node/db/l2db"
 	"github.com/hermeznetwork/hermez-node/log"
 	"github.com/hermeznetwork/hermez-node/node"
 	"github.com/hermeznetwork/tracerr"
@@ -23,6 +25,7 @@ const (
 	flagMode  = "mode"
 	flagSK    = "privatekey"
 	flagYes   = "yes"
+	flagBlock = "block"
 	modeSync  = "sync"
 	modeCoord = "coord"
 )
@@ -139,6 +142,47 @@ func cmdRun(c *cli.Context) error {
 	return nil
 }
 
+func cmdDiscard(c *cli.Context) error {
+	_cfg, err := parseCli(c)
+	if err != nil {
+		return tracerr.Wrap(fmt.Errorf("error parsing flags and config: %w", err))
+	}
+	cfg := _cfg.node
+	blockNum := c.Int64(flagBlock)
+	log.Infof("Discarding all blocks up to block %v...", blockNum)
+
+	db, err := dbUtils.InitSQLDB(
+		cfg.PostgreSQL.Port,
+		cfg.PostgreSQL.Host,
+		cfg.PostgreSQL.User,
+		cfg.PostgreSQL.Password,
+		cfg.PostgreSQL.Name,
+	)
+	if err != nil {
+		return tracerr.Wrap(fmt.Errorf("dbUtils.InitSQLDB: %w", err))
+	}
+	historyDB := historydb.NewHistoryDB(db, nil)
+	if err := historyDB.Reorg(blockNum); err != nil {
+		return tracerr.Wrap(fmt.Errorf("historyDB.Reorg: %w", err))
+	}
+	batchNum, err := historyDB.GetLastBatchNum()
+	if err != nil {
+		return tracerr.Wrap(fmt.Errorf("historyDB.GetLastBatchNum: %w", err))
+	}
+	l2DB := l2db.NewL2DB(
+		db,
+		cfg.Coordinator.L2DB.SafetyPeriod,
+		cfg.Coordinator.L2DB.MaxTxs,
+		cfg.Coordinator.L2DB.TTL.Duration,
+		nil,
+	)
+	if err := l2DB.Reorg(batchNum); err != nil {
+		return tracerr.Wrap(fmt.Errorf("l2DB.Reorg: %w", err))
+	}
+
+	return nil
+}
+
 // Config is the configuration of the hermez node execution
 type Config struct {
 	mode node.Mode
@@ -239,6 +283,18 @@ func main() {
 			Usage:   "Run the hermez-node in the indicated mode",
 			Action:  cmdRun,
 		},
+		{
+			Name:    "discard",
+			Aliases: []string{},
+			Usage:   "Discard blocks up to a specified block number",
+			Action:  cmdDiscard,
+			Flags: []cli.Flag{
+				&cli.Int64Flag{
+					Name:     flagBlock,
+					Usage:    "last block number to keep",
+					Required: false,
+				}},
+		},
 	}
 
 	err := app.Run(os.Args)