core/rawdb: untight freezer and ancient chain data

Previously freezer is only used for storing ancient chain data, while
obviously it can be used more. This PR untight the chain data and freezer,
keep the minimal freezer structure and move all other logics(like freezing)
into a separate structure called ChainFreezer.

core/rawdb/chain_freezer.go

@@ -0,0 +1,300 @@
+// Copyright 2022 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package rawdb
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+const (
+	// freezerRecheckInterval is the frequency to check the key-value database for
+	// chain progression that might permit new blocks to be frozen into immutable
+	// storage.
+	freezerRecheckInterval = time.Minute
+
+	// freezerBatchLimit is the maximum number of blocks to freeze in one batch
+	// before doing an fsync and deleting it from the key-value store.
+	freezerBatchLimit = 30000
+)
+
+// chainFreezer is a wrapper of freezer with additional chain freezing feature.
+// The background thread will keep moving ancient chain segments from key-value
+// database to flat files for saving space on live database.
+type chainFreezer struct {
+	*Freezer
+
+	threshold uint64 // Number of recent blocks not to freeze (params.FullImmutabilityThreshold apart from tests)
+	quit      chan struct{}
+	wg        sync.WaitGroup
+	closeOnce sync.Once
+	trigger   chan chan struct{} // Manual blocking freeze trigger, test determinism
+}
+
+// newChainFreezer initializes the freezer for ancient chain data.
+func newChainFreezer(datadir string, namespace string, readonly bool, maxTableSize uint32, tables map[string]bool) (*chainFreezer, error) {
+	freezer, err := NewFreezer(datadir, namespace, readonly, maxTableSize, tables)
+	if err != nil {
+		return nil, err
+	}
+	return &chainFreezer{
+		Freezer:   freezer,
+		threshold: params.FullImmutabilityThreshold,
+		quit:      make(chan struct{}),
+		trigger:   make(chan chan struct{}),
+	}, nil
+}
+
+// Close closes the chain freezer instance and terminates the background thread.
+func (f *chainFreezer) Close() error {
+	err := f.Freezer.Close()
+	select {
+	case <-f.quit:
+	default:
+		close(f.quit)
+	}
+	f.wg.Wait()
+	return err
+}
+
+// freeze is a background thread that periodically checks the blockchain for any
+// import progress and moves ancient data from the fast database into the freezer.
+//
+// This functionality is deliberately broken off from block importing to avoid
+// incurring additional data shuffling delays on block propagation.
+func (f *chainFreezer) freeze(db ethdb.KeyValueStore) {
+	nfdb := &nofreezedb{KeyValueStore: db}
+
+	var (
+		backoff   bool
+		triggered chan struct{} // Used in tests
+	)
+	for {
+		select {
+		case <-f.quit:
+			log.Info("Freezer shutting down")
+			return
+		default:
+		}
+		if backoff {
+			// If we were doing a manual trigger, notify it
+			if triggered != nil {
+				triggered <- struct{}{}
+				triggered = nil
+			}
+			select {
+			case <-time.NewTimer(freezerRecheckInterval).C:
+				backoff = false
+			case triggered = <-f.trigger:
+				backoff = false
+			case <-f.quit:
+				return
+			}
+		}
+		// Retrieve the freezing threshold.
+		hash := ReadHeadBlockHash(nfdb)
+		if hash == (common.Hash{}) {
+			log.Debug("Current full block hash unavailable") // new chain, empty database
+			backoff = true
+			continue
+		}
+		number := ReadHeaderNumber(nfdb, hash)
+		threshold := atomic.LoadUint64(&f.threshold)
+
+		switch {
+		case number == nil:
+			log.Error("Current full block number unavailable", "hash", hash)
+			backoff = true
+			continue
+
+		case *number < threshold:
+			log.Debug("Current full block not old enough", "number", *number, "hash", hash, "delay", threshold)
+			backoff = true
+			continue
+
+		case *number-threshold <= f.frozen:
+			log.Debug("Ancient blocks frozen already", "number", *number, "hash", hash, "frozen", f.frozen)
+			backoff = true
+			continue
+		}
+		head := ReadHeader(nfdb, hash, *number)
+		if head == nil {
+			log.Error("Current full block unavailable", "number", *number, "hash", hash)
+			backoff = true
+			continue
+		}
+
+		// Seems we have data ready to be frozen, process in usable batches
+		var (
+			start    = time.Now()
+			first, _ = f.Ancients()
+			limit    = *number - threshold
+		)
+		if limit-first > freezerBatchLimit {
+			limit = first + freezerBatchLimit
+		}
+		ancients, err := f.freezeRange(nfdb, first, limit)
+		if err != nil {
+			log.Error("Error in block freeze operation", "err", err)
+			backoff = true
+			continue
+		}
+
+		// Batch of blocks have been frozen, flush them before wiping from leveldb
+		if err := f.Sync(); err != nil {
+			log.Crit("Failed to flush frozen tables", "err", err)
+		}
+
+		// Wipe out all data from the active database
+		batch := db.NewBatch()
+		for i := 0; i < len(ancients); i++ {
+			// Always keep the genesis block in active database
+			if first+uint64(i) != 0 {
+				DeleteBlockWithoutNumber(batch, ancients[i], first+uint64(i))
+				DeleteCanonicalHash(batch, first+uint64(i))
+			}
+		}
+		if err := batch.Write(); err != nil {
+			log.Crit("Failed to delete frozen canonical blocks", "err", err)
+		}
+		batch.Reset()
+
+		// Wipe out side chains also and track dangling side chains
+		var dangling []common.Hash
+		for number := first; number < f.frozen; number++ {
+			// Always keep the genesis block in active database
+			if number != 0 {
+				dangling = ReadAllHashes(db, number)
+				for _, hash := range dangling {
+					log.Trace("Deleting side chain", "number", number, "hash", hash)
+					DeleteBlock(batch, hash, number)
+				}
+			}
+		}
+		if err := batch.Write(); err != nil {
+			log.Crit("Failed to delete frozen side blocks", "err", err)
+		}
+		batch.Reset()
+
+		// Step into the future and delete and dangling side chains
+		if f.frozen > 0 {
+			tip := f.frozen
+			for len(dangling) > 0 {
+				drop := make(map[common.Hash]struct{})
+				for _, hash := range dangling {
+					log.Debug("Dangling parent from Freezer", "number", tip-1, "hash", hash)
+					drop[hash] = struct{}{}
+				}
+				children := ReadAllHashes(db, tip)
+				for i := 0; i < len(children); i++ {
+					// Dig up the child and ensure it's dangling
+					child := ReadHeader(nfdb, children[i], tip)
+					if child == nil {
+						log.Error("Missing dangling header", "number", tip, "hash", children[i])
+						continue
+					}
+					if _, ok := drop[child.ParentHash]; !ok {
+						children = append(children[:i], children[i+1:]...)
+						i--
+						continue
+					}
+					// Delete all block data associated with the child
+					log.Debug("Deleting dangling block", "number", tip, "hash", children[i], "parent", child.ParentHash)
+					DeleteBlock(batch, children[i], tip)
+				}
+				dangling = children
+				tip++
+			}
+			if err := batch.Write(); err != nil {
+				log.Crit("Failed to delete dangling side blocks", "err", err)
+			}
+		}
+
+		// Log something friendly for the user
+		context := []interface{}{
+			"blocks", f.frozen - first, "elapsed", common.PrettyDuration(time.Since(start)), "number", f.frozen - 1,
+		}
+		if n := len(ancients); n > 0 {
+			context = append(context, []interface{}{"hash", ancients[n-1]}...)
+		}
+		log.Info("Deep froze chain segment", context...)
+
+		// Avoid database thrashing with tiny writes
+		if f.frozen-first < freezerBatchLimit {
+			backoff = true
+		}
+	}
+}
+
+func (f *chainFreezer) freezeRange(nfdb *nofreezedb, number, limit uint64) (hashes []common.Hash, err error) {
+	hashes = make([]common.Hash, 0, limit-number)
+
+	_, err = f.ModifyAncients(func(op ethdb.AncientWriteOp) error {
+		for ; number <= limit; number++ {
+			// Retrieve all the components of the canonical block.
+			hash := ReadCanonicalHash(nfdb, number)
+			if hash == (common.Hash{}) {
+				return fmt.Errorf("canonical hash missing, can't freeze block %d", number)
+			}
+			header := ReadHeaderRLP(nfdb, hash, number)
+			if len(header) == 0 {
+				return fmt.Errorf("block header missing, can't freeze block %d", number)
+			}
+			body := ReadBodyRLP(nfdb, hash, number)
+			if len(body) == 0 {
+				return fmt.Errorf("block body missing, can't freeze block %d", number)
+			}
+			receipts := ReadReceiptsRLP(nfdb, hash, number)
+			if len(receipts) == 0 {
+				return fmt.Errorf("block receipts missing, can't freeze block %d", number)
+			}
+			td := ReadTdRLP(nfdb, hash, number)
+			if len(td) == 0 {
+				return fmt.Errorf("total difficulty missing, can't freeze block %d", number)
+			}
+
+			// Write to the batch.
+			if err := op.AppendRaw(freezerHashTable, number, hash[:]); err != nil {
+				return fmt.Errorf("can't write hash to Freezer: %v", err)
+			}
+			if err := op.AppendRaw(freezerHeaderTable, number, header); err != nil {
+				return fmt.Errorf("can't write header to Freezer: %v", err)
+			}
+			if err := op.AppendRaw(freezerBodiesTable, number, body); err != nil {
+				return fmt.Errorf("can't write body to Freezer: %v", err)
+			}
+			if err := op.AppendRaw(freezerReceiptTable, number, receipts); err != nil {
+				return fmt.Errorf("can't write receipts to Freezer: %v", err)
+			}
+			if err := op.AppendRaw(freezerDifficultyTable, number, td); err != nil {
+				return fmt.Errorf("can't write td to Freezer: %v", err)
+			}
+
+			hashes = append(hashes, hash)
+		}
+		return nil
+	})
+
+	return hashes, err
+}

core/rawdb/database.go

@@ -58,18 +58,18 @@ func (frdb *freezerdb) Close() error {
 // a freeze cycle completes, without having to sleep for a minute to trigger the
 // automatic background run.
 func (frdb *freezerdb) Freeze(threshold uint64) error {
-	if frdb.AncientStore.(*freezer).readonly {
+	if frdb.AncientStore.(*chainFreezer).readonly {
 		return errReadOnly
 	}
 	// Set the freezer threshold to a temporary value
 	defer func(old uint64) {
-		atomic.StoreUint64(&frdb.AncientStore.(*freezer).threshold, old)
-	}(atomic.LoadUint64(&frdb.AncientStore.(*freezer).threshold))
-	atomic.StoreUint64(&frdb.AncientStore.(*freezer).threshold, threshold)
+		atomic.StoreUint64(&frdb.AncientStore.(*chainFreezer).threshold, old)
+	}(atomic.LoadUint64(&frdb.AncientStore.(*chainFreezer).threshold))
+	atomic.StoreUint64(&frdb.AncientStore.(*chainFreezer).threshold, threshold)
 
 	// Trigger a freeze cycle and block until it's done
 	trigger := make(chan struct{}, 1)
-	frdb.AncientStore.(*freezer).trigger <- trigger
+	frdb.AncientStore.(*chainFreezer).trigger <- trigger
 	<-trigger
 	return nil
 }
@@ -162,7 +162,7 @@ func NewDatabase(db ethdb.KeyValueStore) ethdb.Database {
 // storage.
 func NewDatabaseWithFreezer(db ethdb.KeyValueStore, freezer string, namespace string, readonly bool) (ethdb.Database, error) {
 	// Create the idle freezer instance
-	frdb, err := newFreezer(freezer, namespace, readonly, freezerTableSize, FreezerNoSnappy)
+	frdb, err := newChainFreezer(freezer, namespace, readonly, freezerTableSize, FreezerNoSnappy)
 	if err != nil {
 		return nil, err
 	}