core, les, light: implement timestamp based sethead and genesis rewinds

Author: karalabe

core/blockchain.go

@@ -318,7 +318,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 		if diskRoot != (common.Hash{}) {
 			log.Warn("Head state missing, repairing", "number", head.Number(), "hash", head.Hash(), "snaproot", diskRoot)
 
-			snapDisk, err := bc.setHeadBeyondRoot(head.NumberU64(), diskRoot, true)
+			snapDisk, err := bc.setHeadBeyondRoot(head.NumberU64(), 0, diskRoot, true)
 			if err != nil {
 				return nil, err
 			}
@@ -328,7 +328,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 			}
 		} else {
 			log.Warn("Head state missing, repairing", "number", head.Number(), "hash", head.Hash())
-			if _, err := bc.setHeadBeyondRoot(head.NumberU64(), common.Hash{}, true); err != nil {
+			if _, err := bc.setHeadBeyondRoot(head.NumberU64(), 0, common.Hash{}, true); err != nil {
 				return nil, err
 			}
 		}
@@ -428,7 +428,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 	if compat, ok := genesisErr.(*params.ConfigCompatError); ok {
 		log.Warn("Rewinding chain to upgrade configuration", "err", compat)
 		if compat.RewindToTime > 0 {
-			log.Crit("Timestamp based rewinds not implemented yet /sad")
+			bc.SetHeadWithTimestamp(compat.RewindToTime)
 		} else {
 			bc.SetHead(compat.RewindToBlock)
 		}
@@ -536,7 +536,20 @@ func (bc *BlockChain) loadLastState() error {
 // was fast synced or full synced and in which state, the method will try to
 // delete minimal data from disk whilst retaining chain consistency.
 func (bc *BlockChain) SetHead(head uint64) error {
-	if _, err := bc.setHeadBeyondRoot(head, common.Hash{}, false); err != nil {
+	if _, err := bc.setHeadBeyondRoot(head, 0, common.Hash{}, false); err != nil {
+		return err
+	}
+	// Send chain head event to update the transaction pool
+	bc.chainHeadFeed.Send(ChainHeadEvent{Block: bc.CurrentBlock()})
+	return nil
+}
+
+// SetHeadWithTimestamp rewinds the local chain to a new head that has at max
+// the given timestamp. Depending on whether the node was fast synced or full
+// synced and in which state, the method will try to delete minimal data from
+// disk whilst retaining chain consistency.
+func (bc *BlockChain) SetHeadWithTimestamp(timestamp uint64) error {
+	if _, err := bc.setHeadBeyondRoot(0, timestamp, common.Hash{}, false); err != nil {
 		return err
 	}
 	// Send chain head event to update the transaction pool
@@ -573,8 +586,12 @@ func (bc *BlockChain) SetSafe(block *types.Block) {
 // in which state, the method will try to delete minimal data from disk whilst
 // retaining chain consistency.
 //
+// The method also works in timestamp mode if `head == 0` but `time != 0`. In that
+// case blocks are rolled back until the new head becomes older or equal to the
+// requested time. If both `head` and `time` is 0, the chain is rewound to genesis.
+//
 // The method returns the block number where the requested root cap was found.
-func (bc *BlockChain) setHeadBeyondRoot(head uint64, root common.Hash, repair bool) (uint64, error) {
+func (bc *BlockChain) setHeadBeyondRoot(head uint64, time uint64, root common.Hash, repair bool) (uint64, error) {
 	if !bc.chainmu.TryLock() {
 		return 0, errChainStopped
 	}
@@ -588,7 +605,7 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, root common.Hash, repair bo
 	pivot := rawdb.ReadLastPivotNumber(bc.db)
 	frozen, _ := bc.db.Ancients()
 
-	updateFn := func(db ethdb.KeyValueWriter, header *types.Header) (uint64, bool) {
+	updateFn := func(db ethdb.KeyValueWriter, header *types.Header) (*types.Header, bool) {
 		// Rewind the blockchain, ensuring we don't end up with a stateless head
 		// block. Note, depth equality is permitted to allow using SetHead as a
 		// chain reparation mechanism without deleting any data!
@@ -669,16 +686,18 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, root common.Hash, repair bo
 			bc.currentFastBlock.Store(newHeadFastBlock)
 			headFastBlockGauge.Update(int64(newHeadFastBlock.NumberU64()))
 		}
-		head := bc.CurrentBlock().NumberU64()
-
+		var (
+			headHeader = bc.CurrentBlock().Header()
+			headNumber = headHeader.Number.Uint64()
+		)
 		// If setHead underflown the freezer threshold and the block processing
 		// intent afterwards is full block importing, delete the chain segment
 		// between the stateful-block and the sethead target.
 		var wipe bool
-		if head+1 < frozen {
-			wipe = pivot == nil || head >= *pivot
+		if headNumber+1 < frozen {
+			wipe = pivot == nil || headNumber >= *pivot
 		}
-		return head, wipe // Only force wipe if full synced
+		return headHeader, wipe // Only force wipe if full synced
 	}
 	// Rewind the header chain, deleting all block bodies until then
 	delFn := func(db ethdb.KeyValueWriter, hash common.Hash, num uint64) {
@@ -705,13 +724,18 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, root common.Hash, repair bo
 	// touching the header chain altogether, unless the freezer is broken
 	if repair {
 		if target, force := updateFn(bc.db, bc.CurrentBlock().Header()); force {
-			bc.hc.SetHead(target, updateFn, delFn)
+			bc.hc.SetHead(target.Number.Uint64(), updateFn, delFn)
 		}
 	} else {
 		// Rewind the chain to the requested head and keep going backwards until a
 		// block with a state is found or fast sync pivot is passed
-		log.Warn("Rewinding blockchain", "target", head)
-		bc.hc.SetHead(head, updateFn, delFn)
+		if time > 0 {
+			log.Warn("Rewinding blockchain to timestamp", "target", time)
+			bc.hc.SetHeadWithTimestamp(time, updateFn, delFn)
+		} else {
+			log.Warn("Rewinding blockchain to block", "target", head)
+			bc.hc.SetHead(head, updateFn, delFn)
+		}
 	}
 	// Clear out any stale content from the caches
 	bc.bodyCache.Purge()

core/headerchain.go

@@ -556,7 +556,7 @@ type (
 	// before head header is updated. The method will return the actual block it
 	// updated the head to (missing state) and a flag if setHead should continue
 	// rewinding till that forcefully (exceeded ancient limits)
-	UpdateHeadBlocksCallback func(ethdb.KeyValueWriter, *types.Header) (uint64, bool)
+	UpdateHeadBlocksCallback func(ethdb.KeyValueWriter, *types.Header) (*types.Header, bool)
 
 	// DeleteBlockContentCallback is a callback function that is called by SetHead
 	// before each header is deleted.
@@ -566,15 +566,33 @@ type (
 // SetHead rewinds the local chain to a new head. Everything above the new head
 // will be deleted and the new one set.
 func (hc *HeaderChain) SetHead(head uint64, updateFn UpdateHeadBlocksCallback, delFn DeleteBlockContentCallback) {
+	hc.setHead(head, 0, updateFn, delFn)
+}
+
+// SetHeadWithTimestamp rewinds the local chain to a new head timestamp. Everything
+// above the new head will be deleted and the new one set.
+func (hc *HeaderChain) SetHeadWithTimestamp(time uint64, updateFn UpdateHeadBlocksCallback, delFn DeleteBlockContentCallback) {
+	hc.setHead(0, time, updateFn, delFn)
+}
+
+// setHead rewinds the local chain to a new head block or a head timestamp.
+// Everything above the new head will be deleted and the new one set.
+func (hc *HeaderChain) setHead(headBlock uint64, headTime uint64, updateFn UpdateHeadBlocksCallback, delFn DeleteBlockContentCallback) {
 	var (
 		parentHash common.Hash
 		batch      = hc.chainDb.NewBatch()
 		origin     = true
 	)
-	for hdr := hc.CurrentHeader(); hdr != nil && hdr.Number.Uint64() > head; hdr = hc.CurrentHeader() {
+	done := func(header *types.Header) bool {
+		if headBlock != 0 || headTime == 0 {
+			return header.Number.Uint64() <= headBlock
+		}
+		return header.Time <= headTime
+	}
+	for hdr := hc.CurrentHeader(); hdr != nil && !done(hdr); hdr = hc.CurrentHeader() {
 		num := hdr.Number.Uint64()
 
-		// Rewind block chain to new head.
+		// Rewind chain to new head
 		parent := hc.GetHeader(hdr.ParentHash, num-1)
 		if parent == nil {
 			parent = hc.genesisHeader
@@ -591,9 +609,9 @@ func (hc *HeaderChain) SetHead(head uint64, updateFn UpdateHeadBlocksCallback, d
 		markerBatch := hc.chainDb.NewBatch()
 		if updateFn != nil {
 			newHead, force := updateFn(markerBatch, parent)
-			if force && newHead < head {
-				log.Warn("Force rewinding till ancient limit", "head", newHead)
-				head = newHead
+			if force && ((headTime > 0 && newHead.Time < headTime) || (headTime == 0 && newHead.Number.Uint64() < headBlock)) {
+				log.Warn("Force rewinding till ancient limit", "head", newHead.Number.Uint64())
+				headBlock, headTime = newHead.Number.Uint64(), 0
 			}
 		}
 		// Update head header then.

les/client.go

@@ -180,7 +180,7 @@ func New(stack *node.Node, config *ethconfig.Config) (*LightEthereum, error) {
 	if compat, ok := genesisErr.(*params.ConfigCompatError); ok {
 		log.Warn("Rewinding chain to upgrade configuration", "err", compat)
 		if compat.RewindToTime > 0 {
-			log.Crit("Timestamp based rewinds not implemented yet /sad")
+			leth.blockchain.SetHeadWithTimestamp(compat.RewindToTime)
 		} else {
 			leth.blockchain.SetHead(compat.RewindToBlock)
 		}

light/lightchain.go

@@ -178,6 +178,17 @@ func (lc *LightChain) SetHead(head uint64) error {
 	return lc.loadLastState()
 }
 
+// SetHeadWithTimestamp rewinds the local chain to a new head that has at max
+// the given timestamp. Everything above the new head will be deleted and the
+// new one set.
+func (lc *LightChain) SetHeadWithTimestamp(timestamp uint64) error {
+	lc.chainmu.Lock()
+	defer lc.chainmu.Unlock()
+
+	lc.hc.SetHeadWithTimestamp(timestamp, nil, nil)
+	return lc.loadLastState()
+}
+
 // GasLimit returns the gas limit of the current HEAD block.
 func (lc *LightChain) GasLimit() uint64 {
 	return lc.hc.CurrentHeader().GasLimit