l2geth: remove dead code in `blockchain.go` and `miner/worker.go`

This PR removes dead code that was responsible for timestamp management.
This codepath is no longer used so removing it will reduce the diff.

.changeset/small-swans-punch.md

+---
+'@eth-optimism/l2geth': patch
+---
+
+Remove dead code in `blockchain.go` and `miner/worker.go`

l2geth/core/blockchain.go

@@ -151,8 +151,6 @@ type BlockChain struct {
 
 	chainmu sync.RWMutex // blockchain insertion lock
 
-	currentTimestamp atomic.Value // Timestamp to be used when mining the current block.
-
 	currentBlock     atomic.Value // Current head of the block chain
 	currentFastBlock atomic.Value // Current head of the fast-sync chain (may be above the block chain!)
 
@@ -249,13 +247,6 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *par
 	// it in advance.
 	bc.engine.VerifyHeader(bc, bc.CurrentHeader(), true)
 
-	if currentHeader := bc.CurrentHeader(); currentHeader != nil {
-		log.Debug("Read timestamp from last block. ", "timestamp", bc.CurrentHeader().Time)
-		bc.SetCurrentTimestamp(int64(bc.CurrentHeader().Time))
-	} else {
-		bc.SetCurrentTimestamp(int64(0))
-	}
-
 	if frozen, err := bc.db.Ancients(); err == nil && frozen > 0 {
 		var (
 			needRewind bool
@@ -504,17 +495,6 @@ func (bc *BlockChain) GasLimit() uint64 {
 	return bc.CurrentBlock().GasLimit()
 }
 
-// SetCurrentTimestamp sets the timestamp for blocks added to the canonical chain.
-func (bc *BlockChain) SetCurrentTimestamp(timestamp int64) {
-	bc.currentTimestamp.Store(&timestamp)
-}
-
-// CurrentTimestamp retrieves the timestamp used for blocks added to the canonical chain.
-func (bc *BlockChain) CurrentTimestamp() int64 {
-	// Note: Can never be nil
-	return *bc.currentTimestamp.Load().(*int64)
-}
-
 // CurrentBlock retrieves the current head block of the canonical chain. The
 // block is retrieved from the blockchain's internal cache.
 func (bc *BlockChain) CurrentBlock() *types.Block {

l2geth/eth/api_backend.go

@@ -323,10 +323,6 @@ func (b *EthAPIBackend) SendTx(ctx context.Context, signedTx *types.Transaction)
 	return b.eth.txPool.AddLocal(signedTx)
 }
 
-func (b *EthAPIBackend) SetTimestamp(timestamp int64) {
-	b.eth.blockchain.SetCurrentTimestamp(timestamp)
-}
-
 func (b *EthAPIBackend) GetPoolTransactions() (types.Transactions, error) {
 	pending, err := b.eth.txPool.Pending()
 	if err != nil {

l2geth/internal/ethapi/backend.go

@@ -86,7 +86,6 @@ type Backend interface {
 	CurrentBlock() *types.Block
 
 	// Optimism-specific API
-	SetTimestamp(timestamp int64)
 	IsVerifier() bool
 	IsSyncing() bool
 	GetEthContext() (uint64, uint64)

l2geth/miner/worker.go

@@ -352,7 +352,6 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 		select {
 		case <-w.startCh:
 			clearPending(w.chain.CurrentBlock().NumberU64())
-			timestamp = w.chain.CurrentTimestamp()
 			commit(false, commitInterruptNewHead)
 
 		case <-timer.C:
@@ -364,7 +363,6 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 					timer.Reset(recommit)
 					continue
 				}
-				timestamp = w.chain.CurrentTimestamp()
 				commit(true, commitInterruptResubmit)
 			}
 
@@ -510,7 +508,7 @@ func (w *worker) mainLoop() {
 				// If clique is running in dev mode(period is 0), disable
 				// advance sealing here.
 				if w.chainConfig.Clique != nil && w.chainConfig.Clique.Period == 0 {
-					w.commitNewWork(nil, true, w.chain.CurrentTimestamp())
+					w.commitNewWork(nil, true, time.Now().Unix())
 				}
 			}
 			atomic.AddInt32(&w.newTxs, int32(len(ev.Txs)))