From f7326dea9fdc15a1c81d94f7170944e543b0bdcf Mon Sep 17 00:00:00 2001
From: Mark Tyneway <mark.tyneway@gmail.com>
Date: Tue, 12 Jan 2021 17:39:48 -0800
Subject: [PATCH] debug rpc: debug_setL1Head and better l1 timestamp management
 (#184)

* debug rpc: debug_setL1Head and better l1 timestamp management

* tests: add

* rollup: set l1 head fix

* rpc: fix set l1 head

* build: fix

* test: unbreak
---
 eth/api_backend.go         | 31 ++++++++++++++++++++++++++++++-
 internal/ethapi/api.go     |  4 ++++
 internal/ethapi/backend.go |  1 +
 les/api_backend.go         |  4 ++++
 rollup/sync_service.go     | 25 +++++++++++++++++++++++++
 5 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/eth/api_backend.go b/eth/api_backend.go
index 38846c2efaa4..96bd55f6db30 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -38,6 +38,7 @@ import (
 	"github.com/ethereum/go-ethereum/eth/gasprice"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
@@ -104,8 +105,36 @@ func (b *EthAPIBackend) GetDiff(block *big.Int) (diffdb.Diff, error) {
 }
 
 func (b *EthAPIBackend) SetHead(number uint64) {
-	b.eth.protocolManager.downloader.Cancel()
+	if number == 0 {
+		log.Info("Cannot reset to genesis")
+		return
+	}
+	if !b.UsingOVM {
+		b.eth.protocolManager.downloader.Cancel()
+	}
 	b.eth.blockchain.SetHead(number)
+
+	// Make sure to reset the LatestL1{Timestamp,BlockNumber}
+	block := b.eth.blockchain.CurrentBlock()
+	txs := block.Transactions()
+	if len(txs) == 0 {
+		log.Error("No transactions found in block", "number", number)
+		return
+	}
+
+	tx := txs[0]
+	blockNumber := tx.L1BlockNumber()
+	if blockNumber == nil {
+		log.Error("No L1BlockNumber found in transaction", "number", number)
+		return
+	}
+
+	b.eth.syncService.SetLatestL1Timestamp(tx.L1Timestamp())
+	b.eth.syncService.SetLatestL1BlockNumber(blockNumber.Uint64())
+}
+
+func (b *EthAPIBackend) SetL1Head(number uint64) error {
+	return b.eth.syncService.SetL1Head(number)
 }
 
 func (b *EthAPIBackend) HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error) {
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index f3ad6ef8ddbb..81bd66fa3642 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -1966,6 +1966,10 @@ func (api *PrivateDebugAPI) SetHead(number hexutil.Uint64) {
 	api.b.SetHead(uint64(number))
 }
 
+func (api *PrivateDebugAPI) SetL1Head(number hexutil.Uint64) {
+	api.b.SetL1Head(uint64(number))
+}
+
 // PublicNetAPI offers network related RPC methods
 type PublicNetAPI struct {
 	net            *p2p.Server
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 95dd576d24ab..fa6c7ac86009 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -92,6 +92,7 @@ type Backend interface {
 	GetRollupContractAddresses() map[string]*common.Address
 	GetLatestL1BlockNumber() uint64
 	GetLatestL1Timestamp() uint64
+	SetL1Head(number uint64) error
 
 	ChainConfig() *params.ChainConfig
 	CurrentBlock() *types.Block
diff --git a/les/api_backend.go b/les/api_backend.go
index a79fb0f9e010..5de9044873b4 100644
--- a/les/api_backend.go
+++ b/les/api_backend.go
@@ -91,6 +91,10 @@ func (b *LesApiBackend) SetHead(number uint64) {
 	b.eth.blockchain.SetHead(number)
 }
 
+func (b *LesApiBackend) SetL1Head(number uint64) error {
+	panic("unimplemented")
+}
+
 func (b *LesApiBackend) HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error) {
 	if number == rpc.LatestBlockNumber || number == rpc.PendingBlockNumber {
 		return b.eth.blockchain.CurrentHeader(), nil
diff --git a/rollup/sync_service.go b/rollup/sync_service.go
index 07f18fe508a7..bed7addc41fa 100644
--- a/rollup/sync_service.go
+++ b/rollup/sync_service.go
@@ -1286,6 +1286,31 @@ func (s *SyncService) SubscribeNewTxsEvent(ch chan<- core.NewTxsEvent) event.Sub
 	return s.scope.Track(s.txFeed.Subscribe(ch))
 }
 
+// SetL1Head resets the Eth1Data
+// and the LatestL1BlockNumber and LatestL1Timestamp
+func (s *SyncService) SetL1Head(number uint64) error {
+	header, err := s.ethclient.HeaderByNumber(s.ctx, new(big.Int).SetUint64(number))
+	if err != nil {
+		return fmt.Errorf("Cannot fetch block in SetL1Head: %w", err)
+	}
+
+	// Reset the header cache
+	for i := 0; i < len(s.HeaderCache); i++ {
+		s.HeaderCache[i] = nil
+	}
+
+	// Reset the last synced L1 heights
+	rawdb.WriteHeadEth1HeaderHash(s.db, header.Hash())
+	rawdb.WriteHeadEth1HeaderHeight(s.db, header.Number.Uint64())
+	s.HeaderCache[number%headerCacheSize] = header
+
+	s.Eth1Data = Eth1Data{
+		BlockHeight: header.Number.Uint64(),
+		BlockHash:   header.Hash(),
+	}
+	return nil
+}
+
 // Adds the transaction to the mempool so that downstream services
 // can apply it to the state. This should directly play against
 // the state eventually, skipping the mempool.