cmd/geth: add db commands stats, compact, put, get, delete (#22014)

This PR introduces:

- db.put to put a value into the database
- db.get to read a value from the database
- db.delete to delete a value from the database
- db.stats to check compaction info from the database
- db.compact to trigger a db compaction

It also moves inspectdb to db.inspect.

cmd/geth/chaincmd.go

@@ -20,7 +20,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
-	"path/filepath"
 	"runtime"
 	"strconv"
 	"sync/atomic"
@@ -28,7 +27,6 @@ import (
 
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/console/prompt"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -170,18 +168,6 @@ The export-preimages command export hash preimages to an RLP encoded stream`,
 		Category: "BLOCKCHAIN COMMANDS",
 		Description: `
 The first argument must be the directory containing the blockchain to download from`,
-	}
-	removedbCommand = cli.Command{
-		Action:    utils.MigrateFlags(removeDB),
-		Name:      "removedb",
-		Usage:     "Remove blockchain and state databases",
-		ArgsUsage: " ",
-		Flags: []cli.Flag{
-			utils.DataDirFlag,
-		},
-		Category: "BLOCKCHAIN COMMANDS",
-		Description: `
-Remove blockchain and state databases`,
 	}
 	dumpCommand = cli.Command{
 		Action:    utils.MigrateFlags(dump),
@@ -202,25 +188,6 @@ Remove blockchain and state databases`,
 The arguments are interpreted as block numbers or hashes.
 Use "ethereum dump 0" to dump the genesis block.`,
 	}
-	inspectCommand = cli.Command{
-		Action:    utils.MigrateFlags(inspect),
-		Name:      "inspect",
-		Usage:     "Inspect the storage size for each type of data in the database",
-		ArgsUsage: " ",
-		Flags: []cli.Flag{
-			utils.DataDirFlag,
-			utils.AncientFlag,
-			utils.CacheFlag,
-			utils.MainnetFlag,
-			utils.RopstenFlag,
-			utils.RinkebyFlag,
-			utils.GoerliFlag,
-			utils.YoloV3Flag,
-			utils.LegacyTestnetFlag,
-			utils.SyncModeFlag,
-		},
-		Category: "BLOCKCHAIN COMMANDS",
-	}
 )
 
 // initGenesis will initialise the given JSON format genesis file and writes it as
@@ -323,17 +290,7 @@ func importChain(ctx *cli.Context) error {
 	fmt.Printf("Import done in %v.\n\n", time.Since(start))
 
 	// Output pre-compaction stats mostly to see the import trashing
-	stats, err := db.Stat("leveldb.stats")
+	showLeveldbStats(db)
-	if err != nil {
-		utils.Fatalf("Failed to read database stats: %v", err)
-	}
-	fmt.Println(stats)
-
-	ioStats, err := db.Stat("leveldb.iostats")
-	if err != nil {
-		utils.Fatalf("Failed to read database iostats: %v", err)
-	}
-	fmt.Println(ioStats)
 
 	// Print the memory statistics used by the importing
 	mem := new(runtime.MemStats)
@@ -351,22 +308,12 @@ func importChain(ctx *cli.Context) error {
 	// Compact the entire database to more accurately measure disk io and print the stats
 	start = time.Now()
 	fmt.Println("Compacting entire database...")
-	if err = db.Compact(nil, nil); err != nil {
+	if err := db.Compact(nil, nil); err != nil {
 		utils.Fatalf("Compaction failed: %v", err)
 	}
 	fmt.Printf("Compaction done in %v.\n\n", time.Since(start))
 
-	stats, err = db.Stat("leveldb.stats")
+	showLeveldbStats(db)
-	if err != nil {
-		utils.Fatalf("Failed to read database stats: %v", err)
-	}
-	fmt.Println(stats)
-
-	ioStats, err = db.Stat("leveldb.iostats")
-	if err != nil {
-		utils.Fatalf("Failed to read database iostats: %v", err)
-	}
-	fmt.Println(ioStats)
 	return importErr
 }
 
@@ -499,66 +446,6 @@ func copyDb(ctx *cli.Context) error {
 	return nil
 }
 
-func removeDB(ctx *cli.Context) error {
-	stack, config := makeConfigNode(ctx)
-
-	// Remove the full node state database
-	path := stack.ResolvePath("chaindata")
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "full node state database")
-	} else {
-		log.Info("Full node state database missing", "path", path)
-	}
-	// Remove the full node ancient database
-	path = config.Eth.DatabaseFreezer
-	switch {
-	case path == "":
-		path = filepath.Join(stack.ResolvePath("chaindata"), "ancient")
-	case !filepath.IsAbs(path):
-		path = config.Node.ResolvePath(path)
-	}
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "full node ancient database")
-	} else {
-		log.Info("Full node ancient database missing", "path", path)
-	}
-	// Remove the light node database
-	path = stack.ResolvePath("lightchaindata")
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "light node database")
-	} else {
-		log.Info("Light node database missing", "path", path)
-	}
-	return nil
-}
-
-// confirmAndRemoveDB prompts the user for a last confirmation and removes the
-// folder if accepted.
-func confirmAndRemoveDB(database string, kind string) {
-	confirm, err := prompt.Stdin.PromptConfirm(fmt.Sprintf("Remove %s (%s)?", kind, database))
-	switch {
-	case err != nil:
-		utils.Fatalf("%v", err)
-	case !confirm:
-		log.Info("Database deletion skipped", "path", database)
-	default:
-		start := time.Now()
-		filepath.Walk(database, func(path string, info os.FileInfo, err error) error {
-			// If we're at the top level folder, recurse into
-			if path == database {
-				return nil
-			}
-			// Delete all the files, but not subfolders
-			if !info.IsDir() {
-				os.Remove(path)
-				return nil
-			}
-			return filepath.SkipDir
-		})
-		log.Info("Database successfully deleted", "path", database, "elapsed", common.PrettyDuration(time.Since(start)))
-	}
-}
-
 func dump(ctx *cli.Context) error {
 	stack, _ := makeConfigNode(ctx)
 	defer stack.Close()
@@ -598,16 +485,6 @@ func dump(ctx *cli.Context) error {
 	return nil
 }
 
-func inspect(ctx *cli.Context) error {
-	node, _ := makeConfigNode(ctx)
-	defer node.Close()
-
-	_, chainDb := utils.MakeChain(ctx, node, true)
-	defer chainDb.Close()
-
-	return rawdb.InspectDatabase(chainDb)
-}
-
 // hashish returns true for strings that look like hashes.
 func hashish(x string) bool {
 	_, err := strconv.Atoi(x)

cmd/geth/dbcmd.go

@@ -0,0 +1,341 @@
+// Copyright 2020 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/console/prompt"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/ethdb/leveldb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/syndtr/goleveldb/leveldb/opt"
+	"gopkg.in/urfave/cli.v1"
+)
+
+var (
+	removedbCommand = cli.Command{
+		Action:    utils.MigrateFlags(removeDB),
+		Name:      "removedb",
+		Usage:     "Remove blockchain and state databases",
+		ArgsUsage: "",
+		Flags: []cli.Flag{
+			utils.DataDirFlag,
+		},
+		Category: "DATABASE COMMANDS",
+		Description: `
+Remove blockchain and state databases`,
+	}
+	dbCommand = cli.Command{
+		Name:      "db",
+		Usage:     "Low level database operations",
+		ArgsUsage: "",
+		Category:  "DATABASE COMMANDS",
+		Subcommands: []cli.Command{
+			dbInspectCmd,
+			dbStatCmd,
+			dbCompactCmd,
+			dbGetCmd,
+			dbDeleteCmd,
+			dbPutCmd,
+		},
+	}
+	dbInspectCmd = cli.Command{
+		Action:    utils.MigrateFlags(inspect),
+		Name:      "inspect",
+		ArgsUsage: "<prefix> <start>",
+
+		Usage:       "Inspect the storage size for each type of data in the database",
+		Description: `This commands iterates the entire database. If the optional 'prefix' and 'start' arguments are provided, then the iteration is limited to the given subset of data.`,
+	}
+	dbStatCmd = cli.Command{
+		Action: dbStats,
+		Name:   "stats",
+		Usage:  "Print leveldb statistics",
+	}
+	dbCompactCmd = cli.Command{
+		Action: dbCompact,
+		Name:   "compact",
+		Usage:  "Compact leveldb database. WARNING: May take a very long time",
+		Description: `This command performs a database compaction. 
+WARNING: This operation may take a very long time to finish, and may cause database
+corruption if it is aborted during execution'!`,
+	}
+	dbGetCmd = cli.Command{
+		Action:      dbGet,
+		Name:        "get",
+		Usage:       "Show the value of a database key",
+		ArgsUsage:   "<hex-encoded key>",
+		Description: "This command looks up the specified database key from the database.",
+	}
+	dbDeleteCmd = cli.Command{
+		Action:    dbDelete,
+		Name:      "delete",
+		Usage:     "Delete a database key (WARNING: may corrupt your database)",
+		ArgsUsage: "<hex-encoded key>",
+		Description: `This command deletes the specified database key from the database. 
+WARNING: This is a low-level operation which may cause database corruption!`,
+	}
+	dbPutCmd = cli.Command{
+		Action:    dbPut,
+		Name:      "put",
+		Usage:     "Set the value of a database key (WARNING: may corrupt your database)",
+		ArgsUsage: "<hex-encoded key> <hex-encoded value>",
+		Description: `This command sets a given database key to the given value. 
+WARNING: This is a low-level operation which may cause database corruption!`,
+	}
+)
+
+func removeDB(ctx *cli.Context) error {
+	stack, config := makeConfigNode(ctx)
+
+	// Remove the full node state database
+	path := stack.ResolvePath("chaindata")
+	if common.FileExist(path) {
+		confirmAndRemoveDB(path, "full node state database")
+	} else {
+		log.Info("Full node state database missing", "path", path)
+	}
+	// Remove the full node ancient database
+	path = config.Eth.DatabaseFreezer
+	switch {
+	case path == "":
+		path = filepath.Join(stack.ResolvePath("chaindata"), "ancient")
+	case !filepath.IsAbs(path):
+		path = config.Node.ResolvePath(path)
+	}
+	if common.FileExist(path) {
+		confirmAndRemoveDB(path, "full node ancient database")
+	} else {
+		log.Info("Full node ancient database missing", "path", path)
+	}
+	// Remove the light node database
+	path = stack.ResolvePath("lightchaindata")
+	if common.FileExist(path) {
+		confirmAndRemoveDB(path, "light node database")
+	} else {
+		log.Info("Light node database missing", "path", path)
+	}
+	return nil
+}
+
+// confirmAndRemoveDB prompts the user for a last confirmation and removes the
+// folder if accepted.
+func confirmAndRemoveDB(database string, kind string) {
+	confirm, err := prompt.Stdin.PromptConfirm(fmt.Sprintf("Remove %s (%s)?", kind, database))
+	switch {
+	case err != nil:
+		utils.Fatalf("%v", err)
+	case !confirm:
+		log.Info("Database deletion skipped", "path", database)
+	default:
+		start := time.Now()
+		filepath.Walk(database, func(path string, info os.FileInfo, err error) error {
+			// If we're at the top level folder, recurse into
+			if path == database {
+				return nil
+			}
+			// Delete all the files, but not subfolders
+			if !info.IsDir() {
+				os.Remove(path)
+				return nil
+			}
+			return filepath.SkipDir
+		})
+		log.Info("Database successfully deleted", "path", database, "elapsed", common.PrettyDuration(time.Since(start)))
+	}
+}
+
+func inspect(ctx *cli.Context) error {
+	var (
+		prefix []byte
+		start  []byte
+	)
+	if ctx.NArg() > 2 {
+		return fmt.Errorf("Max 2 arguments: %v", ctx.Command.ArgsUsage)
+	}
+	if ctx.NArg() >= 1 {
+		if d, err := hexutil.Decode(ctx.Args().Get(0)); err != nil {
+			return fmt.Errorf("failed to hex-decode 'prefix': %v", err)
+		} else {
+			prefix = d
+		}
+	}
+	if ctx.NArg() >= 2 {
+		if d, err := hexutil.Decode(ctx.Args().Get(1)); err != nil {
+			return fmt.Errorf("failed to hex-decode 'start': %v", err)
+		} else {
+			start = d
+		}
+	}
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+
+	_, chainDb := utils.MakeChain(ctx, stack, true)
+	defer chainDb.Close()
+
+	return rawdb.InspectDatabase(chainDb, prefix, start)
+}
+
+func showLeveldbStats(db ethdb.Stater) {
+	if stats, err := db.Stat("leveldb.stats"); err != nil {
+		log.Warn("Failed to read database stats", "error", err)
+	} else {
+		fmt.Println(stats)
+	}
+	if ioStats, err := db.Stat("leveldb.iostats"); err != nil {
+		log.Warn("Failed to read database iostats", "error", err)
+	} else {
+		fmt.Println(ioStats)
+	}
+}
+
+func dbStats(ctx *cli.Context) error {
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+	path := stack.ResolvePath("chaindata")
+	db, err := leveldb.NewCustom(path, "", func(options *opt.Options) {
+		options.ReadOnly = true
+	})
+	if err != nil {
+		return err
+	}
+	showLeveldbStats(db)
+	err = db.Close()
+	if err != nil {
+		log.Info("Close err", "error", err)
+	}
+	return nil
+}
+
+func dbCompact(ctx *cli.Context) error {
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+	path := stack.ResolvePath("chaindata")
+	cache := ctx.GlobalInt(utils.CacheFlag.Name) * ctx.GlobalInt(utils.CacheDatabaseFlag.Name) / 100
+	db, err := leveldb.NewCustom(path, "", func(options *opt.Options) {
+		options.OpenFilesCacheCapacity = utils.MakeDatabaseHandles()
+		options.BlockCacheCapacity = cache / 2 * opt.MiB
+		options.WriteBuffer = cache / 4 * opt.MiB // Two of these are used internally
+	})
+	if err != nil {
+		return err
+	}
+	showLeveldbStats(db)
+	log.Info("Triggering compaction")
+	err = db.Compact(nil, nil)
+	if err != nil {
+		log.Info("Compact err", "error", err)
+	}
+	showLeveldbStats(db)
+	log.Info("Closing db")
+	err = db.Close()
+	if err != nil {
+		log.Info("Close err", "error", err)
+	}
+	log.Info("Exiting")
+	return err
+}
+
+// dbGet shows the value of a given database key
+func dbGet(ctx *cli.Context) error {
+	if ctx.NArg() != 1 {
+		return fmt.Errorf("required arguments: %v", ctx.Command.ArgsUsage)
+	}
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+	path := stack.ResolvePath("chaindata")
+	db, err := leveldb.NewCustom(path, "", func(options *opt.Options) {
+		options.ReadOnly = true
+	})
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+	key, err := hexutil.Decode(ctx.Args().Get(0))
+	if err != nil {
+		log.Info("Could not decode the key", "error", err)
+		return err
+	}
+	data, err := db.Get(key)
+	if err != nil {
+		log.Info("Get operation failed", "error", err)
+		return err
+	}
+	fmt.Printf("key %#x:\n\t%#x\n", key, data)
+	return nil
+}
+
+// dbDelete deletes a key from the database
+func dbDelete(ctx *cli.Context) error {
+	if ctx.NArg() != 1 {
+		return fmt.Errorf("required arguments: %v", ctx.Command.ArgsUsage)
+	}
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+	db := utils.MakeChainDatabase(ctx, stack)
+	defer db.Close()
+	key, err := hexutil.Decode(ctx.Args().Get(0))
+	if err != nil {
+		log.Info("Could not decode the key", "error", err)
+		return err
+	}
+	if err = db.Delete(key); err != nil {
+		log.Info("Delete operation returned an error", "error", err)
+		return err
+	}
+	return nil
+}
+
+// dbPut overwrite a value in the database
+func dbPut(ctx *cli.Context) error {
+	if ctx.NArg() != 2 {
+		return fmt.Errorf("required arguments: %v", ctx.Command.ArgsUsage)
+	}
+	stack, _ := makeConfigNode(ctx)
+	defer stack.Close()
+	db := utils.MakeChainDatabase(ctx, stack)
+	defer db.Close()
+	var (
+		key   []byte
+		value []byte
+		data  []byte
+		err   error
+	)
+	key, err = hexutil.Decode(ctx.Args().Get(0))
+	if err != nil {
+		log.Info("Could not decode the key", "error", err)
+		return err
+	}
+	value, err = hexutil.Decode(ctx.Args().Get(1))
+	if err != nil {
+		log.Info("Could not decode the value", "error", err)
+		return err
+	}
+	data, err = db.Get(key)
+	if err == nil {
+		fmt.Printf("Previous value:\n%#x\n", data)
+	}
+	return db.Put(key, value)
+}

cmd/geth/main.go

@@ -238,7 +238,6 @@ func init() {
 		removedbCommand,
 		dumpCommand,
 		dumpGenesisCommand,
-		inspectCommand,
 		// See accountcmd.go:
 		accountCommand,
 		walletCommand,
@@ -254,6 +253,8 @@ func init() {
 		licenseCommand,
 		// See config.go
 		dumpConfigCommand,
+		// see dbcmd.go
+		dbCommand,
 		// See cmd/utils/flags_legacy.go
 		utils.ShowDeprecated,
 		// See snapshot.go

cmd/utils/flags.go

@@ -1073,9 +1073,9 @@ func setLes(ctx *cli.Context, cfg *ethconfig.Config) {
 	}
 }
 
-// makeDatabaseHandles raises out the number of allowed file handles per process
+// MakeDatabaseHandles raises out the number of allowed file handles per process
 // for Geth and returns half of the allowance to assign to the database.
-func makeDatabaseHandles() int {
+func MakeDatabaseHandles() int {
 	limit, err := fdlimit.Maximum()
 	if err != nil {
 		Fatalf("Failed to retrieve file descriptor allowance: %v", err)
@@ -1546,7 +1546,7 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 	if ctx.GlobalIsSet(CacheFlag.Name) || ctx.GlobalIsSet(CacheDatabaseFlag.Name) {
 		cfg.DatabaseCache = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheDatabaseFlag.Name) / 100
 	}
-	cfg.DatabaseHandles = makeDatabaseHandles()
+	cfg.DatabaseHandles = MakeDatabaseHandles()
 	if ctx.GlobalIsSet(AncientFlag.Name) {
 		cfg.DatabaseFreezer = ctx.GlobalString(AncientFlag.Name)
 	}
@@ -1821,7 +1821,7 @@ func SplitTagsFlag(tagsFlag string) map[string]string {
 func MakeChainDatabase(ctx *cli.Context, stack *node.Node) ethdb.Database {
 	var (
 		cache   = ctx.GlobalInt(CacheFlag.Name) * ctx.GlobalInt(CacheDatabaseFlag.Name) / 100
-		handles = makeDatabaseHandles()
+		handles = MakeDatabaseHandles()
 
 		err     error
 		chainDb ethdb.Database

core/rawdb/database.go

@@ -270,8 +270,8 @@ func (s *stat) Count() string {
 
 // InspectDatabase traverses the entire database and checks the size
 // of all different categories of data.
-func InspectDatabase(db ethdb.Database) error {
+func InspectDatabase(db ethdb.Database, keyPrefix, keyStart []byte) error {
-	it := db.NewIterator(nil, nil)
+	it := db.NewIterator(keyPrefix, keyStart)
 	defer it.Release()
 
 	var (
@@ -307,8 +307,9 @@ func InspectDatabase(db ethdb.Database) error {
 		bloomTrieNodes stat
 
 		// Meta- and unaccounted data
-		metadata    stat
+		metadata     stat
-		unaccounted stat
+		unaccounted  stat
+		shutdownInfo stat
 
 		// Totals
 		total common.StorageSize
@@ -359,6 +360,8 @@ func InspectDatabase(db ethdb.Database) error {
 			bytes.HasPrefix(key, []byte("bltIndex-")) ||
 			bytes.HasPrefix(key, []byte("bltRoot-")): // Bloomtrie sub
 			bloomTrieNodes.Add(size)
+		case bytes.Equal(key, uncleanShutdownKey):
+			shutdownInfo.Add(size)
 		default:
 			var accounted bool
 			for _, meta := range [][]byte{
@@ -413,6 +416,7 @@ func InspectDatabase(db ethdb.Database) error {
 		{"Key-Value store", "Storage snapshot", storageSnaps.Size(), storageSnaps.Count()},
 		{"Key-Value store", "Clique snapshots", cliqueSnaps.Size(), cliqueSnaps.Count()},
 		{"Key-Value store", "Singleton metadata", metadata.Size(), metadata.Count()},
+		{"Key-Value store", "Shutdown metadata", shutdownInfo.Size(), shutdownInfo.Count()},
 		{"Ancient store", "Headers", ancientHeadersSize.String(), ancients.String()},
 		{"Ancient store", "Bodies", ancientBodiesSize.String(), ancients.String()},
 		{"Ancient store", "Receipt lists", ancientReceiptsSize.String(), ancients.String()},

ethdb/leveldb/leveldb.go

@@ -84,24 +84,36 @@ type Database struct {
 // New returns a wrapped LevelDB object. The namespace is the prefix that the
 // metrics reporting should use for surfacing internal stats.
 func New(file string, cache int, handles int, namespace string) (*Database, error) {
-	// Ensure we have some minimal caching and file guarantees
+	return NewCustom(file, namespace, func(options *opt.Options) {
-	if cache < minCache {
+		// Ensure we have some minimal caching and file guarantees
-		cache = minCache
+		if cache < minCache {
-	}
+			cache = minCache
-	if handles < minHandles {
+		}
-		handles = minHandles
+		if handles < minHandles {
-	}
+			handles = minHandles
+		}
+		// Set default options
+		options.OpenFilesCacheCapacity = handles
+		options.BlockCacheCapacity = cache / 2 * opt.MiB
+		options.WriteBuffer = cache / 4 * opt.MiB // Two of these are used internally
+	})
+}
+
+// NewCustom returns a wrapped LevelDB object. The namespace is the prefix that the
+// metrics reporting should use for surfacing internal stats.
+// The customize function allows the caller to modify the leveldb options.
+func NewCustom(file string, namespace string, customize func(options *opt.Options)) (*Database, error) {
+	options := configureOptions(customize)
 	logger := log.New("database", file)
-	logger.Info("Allocated cache and file handles", "cache", common.StorageSize(cache*1024*1024), "handles", handles)
+	usedCache := options.GetBlockCacheCapacity() + options.GetWriteBuffer()*2
+	logCtx := []interface{}{"cache", common.StorageSize(usedCache), "handles", options.GetOpenFilesCacheCapacity()}
+	if options.ReadOnly {
+		logCtx = append(logCtx, "readonly", "true")
+	}
+	logger.Info("Allocated cache and file handles", logCtx...)
 
 	// Open the db and recover any potential corruptions
-	db, err := leveldb.OpenFile(file, &opt.Options{
+	db, err := leveldb.OpenFile(file, options)
-		OpenFilesCacheCapacity: handles,
-		BlockCacheCapacity:     cache / 2 * opt.MiB,
-		WriteBuffer:            cache / 4 * opt.MiB, // Two of these are used internally
-		Filter:                 filter.NewBloomFilter(10),
-		DisableSeeksCompaction: true,
-	})
 	if _, corrupted := err.(*errors.ErrCorrupted); corrupted {
 		db, err = leveldb.RecoverFile(file, nil)
 	}
@@ -133,6 +145,20 @@ func New(file string, cache int, handles int, namespace string) (*Database, erro
 	return ldb, nil
 }
 
+// configureOptions sets some default options, then runs the provided setter.
+func configureOptions(customizeFn func(*opt.Options)) *opt.Options {
+	// Set default options
+	options := &opt.Options{
+		Filter:                 filter.NewBloomFilter(10),
+		DisableSeeksCompaction: true,
+	}
+	// Allow caller to make custom modifications to the options
+	if customizeFn != nil {
+		customizeFn(options)
+	}
+	return options
+}
+
 // Close stops the metrics collection, flushes any pending data to disk and closes
 // all io accesses to the underlying key-value store.
 func (db *Database) Close() error {

internal/flags/helpers.go

@@ -25,7 +25,7 @@ import (
 )
 
 var (
-	CommandHelpTemplate = `{{.cmd.Name}}{{if .cmd.Subcommands}} command{{end}}{{if .cmd.Flags}} [command options]{{end}} [arguments...]
+	CommandHelpTemplate = `{{.cmd.Name}}{{if .cmd.Subcommands}} command{{end}}{{if .cmd.Flags}} [command options]{{end}} {{.cmd.ArgsUsage}}
 {{if .cmd.Description}}{{.cmd.Description}}
 {{end}}{{if .cmd.Subcommands}}
 SUBCOMMANDS:
@@ -36,7 +36,7 @@ SUBCOMMANDS:
 {{end}}
 {{end}}{{end}}`
 
-	OriginCommandHelpTemplate = `{{.Name}}{{if .Subcommands}} command{{end}}{{if .Flags}} [command options]{{end}} [arguments...]
+	OriginCommandHelpTemplate = `{{.Name}}{{if .Subcommands}} command{{end}}{{if .Flags}} [command options]{{end}} {{.ArgsUsage}}
 {{if .Description}}{{.Description}}
 {{end}}{{if .Subcommands}}
 SUBCOMMANDS: