core, ethdb: introduce database sync function (ethereum#31703)

This pull request introduces a SyncKeyValue function to the
ethdb.KeyValueStore
interface, providing the ability to forcibly flush all previous writes
to disk.

This functionality is critical for go-ethereum, which internally uses
two independent
database engines: a key-value store (such as Pebble, LevelDB, or
memoryDB for
testing) and a flat-file–based freezer. To ensure write-order
consistency between
these engines, the key-value store must be explicitly synced before
writing to the
freezer and vice versa.

Fixes
- ethereum#31405
- ethereum#29819

Author: rjl493456442

cmd/geth/dbcmd.go

@@ -1282,7 +1282,7 @@ func hbss2pbss(ctx *cli.Context) error {
 	defer stack.Close()
 
 	db := utils.MakeChainDatabase(ctx, stack, false, false)
-	db.BlockStore().Sync()
+	db.BlockStore().SyncAncient()
 	stateDiskDb := db.StateStore()
 	defer db.Close()
 

core/bench_test.go

@@ -183,7 +183,7 @@ func benchInsertChain(b *testing.B, disk bool, gen func(int, *BlockGen)) {
 	if !disk {
 		db = rawdb.NewMemoryDatabase()
 	} else {
-		pdb, err := pebble.New(b.TempDir(), 128, 128, "", false, true)
+		pdb, err := pebble.New(b.TempDir(), 128, 128, "", false)
 		if err != nil {
 			b.Fatalf("cannot create temporary database: %v", err)
 		}
@@ -304,7 +304,7 @@ func makeChainForBench(db ethdb.Database, genesis *Genesis, full bool, count uin
 func benchWriteChain(b *testing.B, full bool, count uint64) {
 	genesis := &Genesis{Config: params.AllEthashProtocolChanges}
 	for i := 0; i < b.N; i++ {
-		pdb, err := pebble.New(b.TempDir(), 1024, 128, "", false, true)
+		pdb, err := pebble.New(b.TempDir(), 1024, 128, "", false)
 		if err != nil {
 			b.Fatalf("error opening database: %v", err)
 		}
@@ -317,7 +317,7 @@ func benchWriteChain(b *testing.B, full bool, count uint64) {
 func benchReadChain(b *testing.B, full bool, count uint64) {
 	dir := b.TempDir()
 
-	pdb, err := pebble.New(dir, 1024, 128, "", false, true)
+	pdb, err := pebble.New(dir, 1024, 128, "", false)
 	if err != nil {
 		b.Fatalf("error opening database: %v", err)
 	}
@@ -333,7 +333,7 @@ func benchReadChain(b *testing.B, full bool, count uint64) {
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
-		pdb, err = pebble.New(dir, 1024, 128, "", false, true)
+		pdb, err = pebble.New(dir, 1024, 128, "", false)
 		if err != nil {
 			b.Fatalf("error opening database: %v", err)
 		}

core/blockchain.go

@@ -1119,17 +1119,16 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, time uint64, root common.Ha
 		// Ignore the error here since light client won't hit this path
 		frozen, _ := bc.db.BlockStore().Ancients()
 		if num+1 <= frozen {
-			// Truncate all relative data(header, total difficulty, body, receipt
-			// and canonical hash) from ancient store.
-			if _, err := bc.db.BlockStore().TruncateHead(num); err != nil {
-				log.Crit("Failed to truncate ancient data", "number", num, "err", err)
-			}
-			// Remove the hash <-> number mapping from the active store.
-			rawdb.DeleteHeaderNumber(db, hash)
+			// The chain segment, such as the block header, canonical hash,
+			// body, and receipt, will be removed from the ancient store
+			// in one go.
+			//
+			// The hash-to-number mapping in the key-value store will be
+			// removed by the hc.SetHead function.
 		} else {
-			// Remove relative body and receipts from the active store.
-			// The header, total difficulty and canonical hash will be
-			// removed in the hc.SetHead function.
+			// Remove the associated body and receipts from the key-value store.
+			// The header, hash-to-number mapping, and canonical hash will be
+			// removed by the hc.SetHead function.
 			rawdb.DeleteBody(db, hash, num)
 			rawdb.DeleteBlobSidecars(db, hash, num)
 			rawdb.DeleteReceipts(db, hash, num)
@@ -1599,7 +1598,7 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 		size += writeSize
 
 		// Sync the ancient store explicitly to ensure all data has been flushed to disk.
-		if err := bc.db.BlockStore().Sync(); err != nil {
+		if err := bc.db.BlockStore().SyncAncient(); err != nil {
 			return 0, err
 		}
 		// Update the current snap block because all block data is now present in DB.

core/blockchain_repair_test.go

@@ -1767,7 +1767,7 @@ func testRepairWithScheme(t *testing.T, tt *rewindTest, snapshots bool, scheme s
 	datadir := t.TempDir()
 	ancient := filepath.Join(datadir, "ancient")
 
-	pdb, err := pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}
@@ -1861,7 +1861,7 @@ func testRepairWithScheme(t *testing.T, tt *rewindTest, snapshots bool, scheme s
 	chain.stopWithoutSaving()
 
 	// Start a new blockchain back up and see where the repair leads us
-	pdb, err = pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err = pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to reopen persistent key-value database: %v", err)
 	}
@@ -1926,7 +1926,7 @@ func testIssue23496(t *testing.T, scheme string) {
 	datadir := t.TempDir()
 	ancient := filepath.Join(datadir, "ancient")
 
-	pdb, err := pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}
@@ -1984,7 +1984,7 @@ func testIssue23496(t *testing.T, scheme string) {
 	chain.stopWithoutSaving()
 
 	// Start a new blockchain back up and see where the repair leads us
-	pdb, err = pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err = pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to reopen persistent key-value database: %v", err)
 	}

core/blockchain_sethead_test.go

@@ -1971,7 +1971,7 @@ func testSetHeadWithScheme(t *testing.T, tt *rewindTest, snapshots bool, scheme
 	datadir := t.TempDir()
 	ancient := filepath.Join(datadir, "ancient")
 
-	pdb, err := pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}

core/blockchain_snapshot_test.go

@@ -66,7 +66,7 @@ func (basic *snapshotTestBasic) prepare(t *testing.T) (*BlockChain, []*types.Blo
 	datadir := t.TempDir()
 	ancient := filepath.Join(datadir, "ancient")
 
-	pdb, err := pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}
@@ -257,7 +257,7 @@ func (snaptest *crashSnapshotTest) test(t *testing.T) {
 	chain.triedb.Close()
 
 	// Start a new blockchain back up and see where the repair leads us
-	pdb, err := pebble.New(snaptest.datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(snaptest.datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}

core/blockchain_test.go

@@ -2670,7 +2670,7 @@ func testSideImportPrunedBlocks(t *testing.T, scheme string) {
 	datadir := t.TempDir()
 	ancient := path.Join(datadir, "ancient")
 
-	pdb, err := pebble.New(datadir, 0, 0, "", false, true)
+	pdb, err := pebble.New(datadir, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("Failed to create persistent key-value database: %v", err)
 	}

core/headerchain.go

@@ -695,18 +695,51 @@ func (hc *HeaderChain) setHead(headBlock uint64, headTime uint64, updateFn Updat
 				hashes = append(hashes, hdr.Hash())
 			}
 			for _, hash := range hashes {
+				// Remove the associated block body and receipts if required.
+				//
+				// If the block is in the chain freezer, then this delete operation
+				// is actually ineffective.
 				if delFn != nil {
 					delFn(blockBatch, hash, num)
 				}
+				// Remove the hash->number mapping along with the header itself
 				rawdb.DeleteHeader(blockBatch, hash, num)
 				rawdb.DeleteTd(blockBatch, hash, num)
 			}
+			// Remove the number->hash mapping
 			rawdb.DeleteCanonicalHash(blockBatch, num)
 		}
 	}
 	// Flush all accumulated deletions.
 	if err := blockBatch.Write(); err != nil {
-		log.Crit("Failed to rewind block", "error", err)
+		log.Crit("Failed to commit batch in setHead", "err", err)
+	}
+	// Explicitly flush the pending writes in the key-value store to disk, ensuring
+	// data durability of the previous deletions.
+	if err := hc.chainDb.SyncKeyValue(); err != nil {
+		log.Crit("Failed to sync the key-value store in setHead", "err", err)
+	}
+	// Truncate the excessive chain segments in the ancient store.
+	// These are actually deferred deletions from the loop above.
+	//
+	// This step must be performed after synchronizing the key-value store;
+	// otherwise, in the event of a panic, it's theoretically possible to
+	// lose recent key-value store writes while the ancient store deletions
+	// remain, leading to data inconsistency, e.g., the gap between the key
+	// value store and ancient can be created due to unclean shutdown.
+	if delFn != nil {
+		// Ignore the error here since light client won't hit this path
+		frozen, _ := hc.chainDb.Ancients()
+		header := hc.CurrentHeader()
+
+		// Truncate the excessive chain segment above the current chain head
+		// in the ancient store.
+		if header.Number.Uint64()+1 < frozen {
+			_, err := hc.chainDb.BlockStore().TruncateHead(header.Number.Uint64() + 1)
+			if err != nil {
+				log.Crit("Failed to truncate head block", "err", err)
+			}
+		}
 	}
 	// Clear out any stale content from the caches
 	hc.headerCache.Purge()

core/rawdb/chain_freezer.go

@@ -309,7 +309,7 @@ func (f *chainFreezer) freeze(db ethdb.KeyValueStore) {
 			continue
 		}
 		// Batch of blocks have been frozen, flush them before wiping from key-value store
-		if err := f.Sync(); err != nil {
+		if err := f.SyncAncient(); err != nil {
 			log.Crit("Failed to flush frozen tables", "err", err)
 		}
 		// Wipe out all data from the active database

core/rawdb/database.go

@@ -235,8 +235,8 @@ func (db *nofreezedb) ResetTable(kind string, startAt uint64, onlyEmpty bool) er
 	return errNotSupported
 }
 
-// Sync returns an error as we don't have a backing chain freezer.
-func (db *nofreezedb) Sync() error {
+// SyncAncient returns an error as we don't have a backing chain freezer.
+func (db *nofreezedb) SyncAncient() error {
 	return errNotSupported
 }
 
@@ -391,8 +391,8 @@ func (db *emptyfreezedb) ResetTable(kind string, startAt uint64, onlyEmpty bool)
 	return nil
 }
 
-// Sync returns nil for pruned db that we don't have a backing chain freezer.
-func (db *emptyfreezedb) Sync() error {
+// SyncAncient returns nil for pruned db that we don't have a backing chain freezer.
+func (db *emptyfreezedb) SyncAncient() error {
 	return nil
 }