cmd/utils, node: switch to Pebble as the default db if none exists (#27136)

* cmd/utils, node: switch to Pebble as the default db if none exists

* node: fall back to LevelDB on platforms not supporting Pebble

* core/rawdb, node: default to Pebble at the node level

* cmd/geth: fix some tests explicitly using leveldb

* ethdb/pebble: allow double closes, makes tests simpler

cmd/geth/dao_test.go

@@ -121,7 +121,7 @@ func testDAOForkBlockNewChain(t *testing.T, test int, genesis string, expectBloc
 	}
 	// Retrieve the DAO config flag from the database
 	path := filepath.Join(datadir, "geth", "chaindata")
-	db, err := rawdb.NewLevelDBDatabase(path, 0, 0, "", false)
+	db, err := rawdb.NewPebbleDBDatabase(path, 0, 0, "", false)
 	if err != nil {
 		t.Fatalf("test %d: failed to open test database: %v", test, err)
 	}

cmd/geth/genesis_test.go

@@ -146,8 +146,8 @@ func TestCustomBackend(t *testing.T) {
 		return nil
 	}
 	for i, tt := range []backendTest{
-		{ // When not specified, it should default to leveldb
+		{ // When not specified, it should default to pebble
-			execArgs:   []string{"--db.engine", "leveldb"},
+			execArgs:   []string{"--db.engine", "pebble"},
 			execExpect: "0x0000000000001338",
 		},
 		{ // Explicit leveldb

cmd/utils/flags.go

@@ -101,8 +101,8 @@ var (
 	}
 	DBEngineFlag = &cli.StringFlag{
 		Name:     "db.engine",
-		Usage:    "Backing database implementation to use ('leveldb' or 'pebble')",
+		Usage:    "Backing database implementation to use ('pebble' or 'leveldb')",
-		Value:    "leveldb",
+		Value:    node.DefaultConfig.DBEngine,
 		Category: flags.EthCategory,
 	}
 	AncientFlag = &flags.DirectoryFlag{

core/rawdb/database.go

@@ -358,9 +358,15 @@ type OpenOptions struct {
 //
 //	                      type == null          type != null
 //	                   +----------------------------------------
-//	db is non-existent |  leveldb default  |  specified type
+//	db is non-existent |  pebble default  |  specified type
-//	db is existent     |  from db          |  specified type (if compatible)
+//	db is existent     |  from db         |  specified type (if compatible)
 func openKeyValueDatabase(o OpenOptions) (ethdb.Database, error) {
+	// Reject any unsupported database type
+	if len(o.Type) != 0 && o.Type != dbLeveldb && o.Type != dbPebble {
+		return nil, fmt.Errorf("unknown db.engine %v", o.Type)
+	}
+	// Retrieve any pre-existing database's type and use that or the requested one
+	// as long as there's no conflict between the two types
 	existingDb := hasPreexistingDb(o.Directory)
 	if len(existingDb) != 0 && len(o.Type) != 0 && o.Type != existingDb {
 		return nil, fmt.Errorf("db.engine choice was %v but found pre-existing %v database in specified data directory", o.Type, existingDb)
@@ -373,12 +379,19 @@ func openKeyValueDatabase(o OpenOptions) (ethdb.Database, error) {
 			return nil, errors.New("db.engine 'pebble' not supported on this platform")
 		}
 	}
-	if len(o.Type) != 0 && o.Type != dbLeveldb {
+	if o.Type == dbLeveldb || existingDb == dbLeveldb {
-		return nil, fmt.Errorf("unknown db.engine %v", o.Type)
+		log.Info("Using leveldb as the backing database")
+		return NewLevelDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
+	}
+	// No pre-existing database, no user-requested one either. Default to Pebble
+	// on supported platforms and LevelDB on anything else.
+	if PebbleEnabled {
+		log.Info("Defaulting to pebble as the backing database")
+		return NewPebbleDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
+	} else {
+		log.Info("Defaulting to leveldb as the backing database")
+		return NewLevelDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
 	}
-	log.Info("Using leveldb as the backing database")
-	// Use leveldb, either as default (no explicit choice), or pre-existing, or chosen explicitly
-	return NewLevelDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
 }
 
 // Open opens both a disk-based key-value database such as leveldb or pebble, but also

ethdb/pebble/pebble.go

@@ -222,14 +222,17 @@ func (d *Database) Close() error {
 	d.quitLock.Lock()
 	defer d.quitLock.Unlock()
 
-	if d.quitChan != nil {
+	// Allow double closing, simplifies things
-		errc := make(chan error)
+	if d.quitChan == nil {
-		d.quitChan <- errc
+		return nil
-		if err := <-errc; err != nil {
-			d.log.Error("Metrics collection failed", "err", err)
-		}
-		d.quitChan = nil
 	}
+	errc := make(chan error)
+	d.quitChan <- errc
+	if err := <-errc; err != nil {
+		d.log.Error("Metrics collection failed", "err", err)
+	}
+	d.quitChan = nil
+
 	return d.db.Close()
 }
 

node/defaults.go

@@ -28,14 +28,12 @@ import (
 )
 
 const (
-	DefaultHTTPHost    = "localhost" // Default host interface for the HTTP RPC server
+	DefaultHTTPHost = "localhost" // Default host interface for the HTTP RPC server
-	DefaultHTTPPort    = 8545        // Default TCP port for the HTTP RPC server
+	DefaultHTTPPort = 8545        // Default TCP port for the HTTP RPC server
-	DefaultWSHost      = "localhost" // Default host interface for the websocket RPC server
+	DefaultWSHost   = "localhost" // Default host interface for the websocket RPC server
-	DefaultWSPort      = 8546        // Default TCP port for the websocket RPC server
+	DefaultWSPort   = 8546        // Default TCP port for the websocket RPC server
-	DefaultGraphQLHost = "localhost" // Default host interface for the GraphQL server
+	DefaultAuthHost = "localhost" // Default host interface for the authenticated apis
-	DefaultGraphQLPort = 8547        // Default TCP port for the GraphQL server
+	DefaultAuthPort = 8551        // Default port for the authenticated apis
-	DefaultAuthHost    = "localhost" // Default host interface for the authenticated apis
-	DefaultAuthPort    = 8551        // Default port for the authenticated apis
 )
 
 var (
@@ -64,7 +62,7 @@ var DefaultConfig = Config{
 		MaxPeers:   50,
 		NAT:        nat.Any(),
 	},
-	DBEngine: "",
+	DBEngine: "", // Use whatever exists, will default to Pebble if non-existent and supported
 }
 
 // DefaultDataDir is the default data directory to use for the databases and other