cmd, core, ethdb, node: move chain freezer one folder deeper (#25487)

* cmd, core, ethdb, node: create chain freezer in a sub folder

* core/rawdb: remove unused code

* core, ethdb, node: add AncientDatadir API back

* cmd, core: extend freezer info dump for sub-ancient-store

* core/rawdb: rework freezer inspector

* core/rawdb: address comments from Peter

* core/rawdb: fix build issue

core/rawdb/database.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"path"
 	"sync/atomic"
 	"time"
 
@@ -34,10 +35,16 @@ import (
 
 // freezerdb is a database wrapper that enabled freezer data retrievals.
 type freezerdb struct {
+	ancientRoot string
 	ethdb.KeyValueStore
 	ethdb.AncientStore
 }
 
+// AncientDatadir returns the path of root ancient directory.
+func (frdb *freezerdb) AncientDatadir() (string, error) {
+	return frdb.ancientRoot, nil
+}
+
 // Close implements io.Closer, closing both the fast key-value store as well as
 // the slow ancient tables.
 func (frdb *freezerdb) Close() error {
@@ -162,12 +169,36 @@ func NewDatabase(db ethdb.KeyValueStore) ethdb.Database {
 	return &nofreezedb{KeyValueStore: db}
 }
 
+// resolveChainFreezerDir is a helper function which resolves the absolute path
+// of chain freezer by considering backward compatibility.
+func resolveChainFreezerDir(ancient string) string {
+	// Check if the chain freezer is already present in the specified
+	// sub folder, if not then two possibilities:
+	// - chain freezer is not initialized
+	// - chain freezer exists in legacy location (root ancient folder)
+	freezer := path.Join(ancient, chainFreezerName)
+	if !common.FileExist(freezer) {
+		if !common.FileExist(ancient) {
+			// The entire ancient store is not initialized, still use the sub
+			// folder for initialization.
+		} else {
+			// Ancient root is already initialized, then we hold the assumption
+			// that chain freezer is also initialized and located in root folder.
+			// In this case fallback to legacy location.
+			freezer = ancient
+			log.Info("Found legacy ancient chain path", "location", ancient)
+		}
+	}
+	return freezer
+}
+
 // NewDatabaseWithFreezer creates a high level database on top of a given key-
 // value data store with a freezer moving immutable chain segments into cold
-// storage.
-func NewDatabaseWithFreezer(db ethdb.KeyValueStore, freezer string, namespace string, readonly bool) (ethdb.Database, error) {
+// storage. The passed ancient indicates the path of root ancient directory
+// where the chain freezer can be opened.
+func NewDatabaseWithFreezer(db ethdb.KeyValueStore, ancient string, namespace string, readonly bool) (ethdb.Database, error) {
 	// Create the idle freezer instance
-	frdb, err := newChainFreezer(freezer, namespace, readonly, freezerTableSize, FreezerNoSnappy)
+	frdb, err := newChainFreezer(resolveChainFreezerDir(ancient), namespace, readonly, freezerTableSize, chainFreezerNoSnappy)
 	if err != nil {
 		return nil, err
 	}
@@ -198,7 +229,7 @@ func NewDatabaseWithFreezer(db ethdb.KeyValueStore, freezer string, namespace st
 			// If the freezer already contains something, ensure that the genesis blocks
 			// match, otherwise we might mix up freezers across chains and destroy both
 			// the freezer and the key-value store.
-			frgenesis, err := frdb.Ancient(freezerHashTable, 0)
+			frgenesis, err := frdb.Ancient(chainFreezerHashTable, 0)
 			if err != nil {
 				return nil, fmt.Errorf("failed to retrieve genesis from ancient %v", err)
 			} else if !bytes.Equal(kvgenesis, frgenesis) {
@@ -244,6 +275,7 @@ func NewDatabaseWithFreezer(db ethdb.KeyValueStore, freezer string, namespace st
 		}()
 	}
 	return &freezerdb{
+		ancientRoot:   ancient,
 		KeyValueStore: db,
 		AncientStore:  frdb,
 	}, nil
@@ -273,13 +305,15 @@ func NewLevelDBDatabase(file string, cache int, handles int, namespace string, r
 }
 
 // NewLevelDBDatabaseWithFreezer creates a persistent key-value database with a
-// freezer moving immutable chain segments into cold storage.
-func NewLevelDBDatabaseWithFreezer(file string, cache int, handles int, freezer string, namespace string, readonly bool) (ethdb.Database, error) {
+// freezer moving immutable chain segments into cold storage. The passed ancient
+// indicates the path of root ancient directory where the chain freezer can be
+// opened.
+func NewLevelDBDatabaseWithFreezer(file string, cache int, handles int, ancient string, namespace string, readonly bool) (ethdb.Database, error) {
 	kvdb, err := leveldb.New(file, cache, handles, namespace, readonly)
 	if err != nil {
 		return nil, err
 	}
-	frdb, err := NewDatabaseWithFreezer(kvdb, freezer, namespace, readonly)
+	frdb, err := NewDatabaseWithFreezer(kvdb, ancient, namespace, readonly)
 	if err != nil {
 		kvdb.Close()
 		return nil, err
@@ -441,7 +475,7 @@ func InspectDatabase(db ethdb.Database, keyPrefix, keyStart []byte) error {
 	}
 	// Inspect append-only file store then.
 	ancientSizes := []*common.StorageSize{&ancientHeadersSize, &ancientBodiesSize, &ancientReceiptsSize, &ancientHashesSize, &ancientTdsSize}
-	for i, category := range []string{freezerHeaderTable, freezerBodiesTable, freezerReceiptTable, freezerHashTable, freezerDifficultyTable} {
+	for i, category := range []string{chainFreezerHeaderTable, chainFreezerBodiesTable, chainFreezerReceiptTable, chainFreezerHashTable, chainFreezerDifficultyTable} {
 		if size, err := db.AncientSize(category); err == nil {
 			*ancientSizes[i] += common.StorageSize(size)
 			total += common.StorageSize(size)