From 40cee945579dc520c12116a6d4cd7938544873da Mon Sep 17 00:00:00 2001
From: Kartik Chopra <k5chopra@edu.uwaterloo.ca>
Date: Fri, 23 Feb 2024 16:28:19 -0500
Subject: [PATCH] Adds a dumb 64 block wait before processing blocks.

---
 cmd/main.go                       | 9 +++++++++
 pkg/l1Listener/l1Listener.go      | 9 ++++++++-
 pkg/l1Listener/l1Listener_test.go | 2 +-
 pkg/node/node.go                  | 3 ++-
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/cmd/main.go b/cmd/main.go
index 3e0b83f..2ea5c53 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -154,6 +154,13 @@ var (
 		EnvVars: []string{"MEV_ORACLE_KEYSTORE_PATH"},
 		Value:   filepath.Join(defaultConfigDir, defaultKeystore),
 	})
+
+	optionWaitOnFinality = altsrc.NewBoolFlag(&cli.BoolFlag{
+		Name:    "wait-on-finality",
+		Usage:   "wait for finality before sending settlement",
+		EnvVars: []string{"MEV_ORACLE_WAIT_ON_FINALITY"},
+		Value:   true,
+	})
 )
 
 func main() {
@@ -175,6 +182,7 @@ func main() {
 		optionOverrideWinners,
 		optionKeystorePath,
 		optionKeystorePassword,
+		optionWaitOnFinality,
 	}
 	app := &cli.App{
 		Name:  "mev-oracle",
@@ -308,6 +316,7 @@ func launchOracleWithConfig(c *cli.Context) error {
 		PgDbname:            c.String(optionPgDbname.Name),
 		LaggerdMode:         c.Int(optionLaggerdMode.Name),
 		OverrideWinners:     c.StringSlice(optionOverrideWinners.Name),
+		WaitOnFinality:      c.Bool(optionWaitOnFinality.Name),
 	})
 	if err != nil {
 		return fmt.Errorf("failed starting node: %w", err)
diff --git a/pkg/l1Listener/l1Listener.go b/pkg/l1Listener/l1Listener.go
index ad6d981..52c86e3 100644
--- a/pkg/l1Listener/l1Listener.go
+++ b/pkg/l1Listener/l1Listener.go
@@ -26,16 +26,19 @@ type L1Listener struct {
 	l1Client       EthClient
 	winnerRegister WinnerRegister
 	metrics        *metrics
+	waitOnFinality bool
 }
 
 func NewL1Listener(
 	l1Client EthClient,
 	winnerRegister WinnerRegister,
+	waitOnFinality bool,
 ) *L1Listener {
 	return &L1Listener{
 		l1Client:       l1Client,
 		winnerRegister: winnerRegister,
 		metrics:        newMetrics(),
+		waitOnFinality: waitOnFinality,
 	}
 }
 
@@ -63,7 +66,11 @@ func (l *L1Listener) Start(ctx context.Context) <-chan struct{} {
 					log.Error().Err(err).Msg("failed to get block number")
 					continue
 				}
-
+				if l.waitOnFinality && blockNum > 64 {
+					// This is a weak proxy for finaility to limit exposure to reorgs
+					// TODO(@ckartik): Interact with Finality gadget to give a more robust implementation.
+					blockNum -= 64
+				}
 				if blockNum <= uint64(currentBlockNo) {
 					continue
 				}
diff --git a/pkg/l1Listener/l1Listener_test.go b/pkg/l1Listener/l1Listener_test.go
index 69c327b..de01f4d 100644
--- a/pkg/l1Listener/l1Listener_test.go
+++ b/pkg/l1Listener/l1Listener_test.go
@@ -25,7 +25,7 @@ func TestL1Listener(t *testing.T) {
 		errC:    make(chan error, 1),
 	}
 
-	l := l1Listener.NewL1Listener(ethClient, reg)
+	l := l1Listener.NewL1Listener(ethClient, reg, true)
 	ctx, cancel := context.WithCancel(context.Background())
 
 	cl := l1Listener.SetCheckInterval(100 * time.Millisecond)
diff --git a/pkg/node/node.go b/pkg/node/node.go
index 592eccc..ca701ec 100644
--- a/pkg/node/node.go
+++ b/pkg/node/node.go
@@ -38,6 +38,7 @@ type Options struct {
 	PgDbname            string
 	LaggerdMode         int
 	OverrideWinners     []string
+	WaitOnFinality      bool
 }
 
 type Node struct {
@@ -127,7 +128,7 @@ func NewNode(opts *Options) (*Node, error) {
 		}
 	}
 
-	l1Lis := l1Listener.NewL1Listener(listenerL1Client, st)
+	l1Lis := l1Listener.NewL1Listener(listenerL1Client, st, opts.WaitOnFinality)
 	l1LisClosed := l1Lis.Start(ctx)
 
 	callOpts := bind.CallOpts{