From e08d82f3a0d5801d08a3a91d8be5809f5d85ee04 Mon Sep 17 00:00:00 2001
From: Sina Mahmoodi <itz.s1na@gmail.com>
Date: Thu, 17 Mar 2022 17:58:17 +0100
Subject: [PATCH] speed-up hack for mainnet

---
 cmd/geth/config.go |  8 +++++++-
 cmd/geth/dbcmd.go  | 35 ++++++++++++++++++++---------------
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/cmd/geth/config.go b/cmd/geth/config.go
index d36a716784c2c..9d69344987478 100644
--- a/cmd/geth/config.go
+++ b/cmd/geth/config.go
@@ -164,7 +164,13 @@ func makeFullNode(ctx *cli.Context) (*node.Node, ethapi.Backend) {
 	backend, eth := utils.RegisterEthService(stack, &cfg.Eth)
 	// Warn users to migrate if they have a legacy freezer format.
 	if eth != nil {
-		isLegacy, _, err := dbHasLegacyReceipts(eth.ChainDb())
+		firstIdx := uint64(0)
+		// Hack to speed up check for mainnet because we know
+		// the first non-empty block.
+		if ctx.GlobalIsSet(utils.MainnetFlag.Name) {
+			firstIdx = 46147
+		}
+		isLegacy, _, err := dbHasLegacyReceipts(eth.ChainDb(), firstIdx)
 		if err != nil {
 			utils.Fatalf("Failed to check db for legacy receipts: %v", err)
 		}
diff --git a/cmd/geth/dbcmd.go b/cmd/geth/dbcmd.go
index 4732bd6f2afe4..f7bebf56f97a7 100644
--- a/cmd/geth/dbcmd.go
+++ b/cmd/geth/dbcmd.go
@@ -787,7 +787,7 @@ func freezerMigrate(ctx *cli.Context) error {
 		return nil
 	}
 
-	isFirstLegacy, firstIdx, err := dbHasLegacyReceipts(db)
+	isFirstLegacy, firstIdx, err := dbHasLegacyReceipts(db, 0)
 	if err != nil {
 		return err
 	}
@@ -812,7 +812,7 @@ func freezerMigrate(ctx *cli.Context) error {
 // dbHasLegacyReceipts checks freezer entries for legacy receipts. It stops at the first
 // non-empty receipt and checks its format. The index of this first non-empty element is
 // the second return parameter.
-func dbHasLegacyReceipts(db ethdb.Database) (bool, uint64, error) {
+func dbHasLegacyReceipts(db ethdb.Database, firstIdx uint64) (bool, uint64, error) {
 	// Check first block for legacy receipt format
 	numAncients, err := db.Ancients()
 	if err != nil {
@@ -821,24 +821,29 @@ func dbHasLegacyReceipts(db ethdb.Database) (bool, uint64, error) {
 	if numAncients < 1 {
 		return false, 0, nil
 	}
+	if firstIdx >= numAncients {
+		return false, firstIdx, nil
+	}
 	var (
 		legacy       bool
-		firstIdx     uint64
 		blob         []byte
 		emptyRLPList = []byte{192}
 	)
-	// Find first block with non-empty receipt
-	for i := uint64(0); i < numAncients; i++ {
-		blob, err = db.Ancient("receipts", i)
-		if err != nil {
-			return false, 0, err
-		}
-		if len(blob) == 0 {
-			continue
-		}
-		if !bytes.Equal(blob, emptyRLPList) {
-			firstIdx = i
-			break
+	// Find first block with non-empty receipt, only if
+	// the index is not already provided.
+	if firstIdx == 0 {
+		for i := uint64(0); i < numAncients; i++ {
+			blob, err = db.Ancient("receipts", i)
+			if err != nil {
+				return false, 0, err
+			}
+			if len(blob) == 0 {
+				continue
+			}
+			if !bytes.Equal(blob, emptyRLPList) {
+				firstIdx = i
+				break
+			}
 		}
 	}
 	// Is first non-empty receipt legacy?