feat(rawdb): skip freezers (#220)

## Why this should be merged

As described in https://github.com/ava-labs/coreth/issues/1137, database
inspection of a Coreth chain database fails because `InspectDatabase()`
expects for freezers to be used. This PR fixes this bug by adding an
option to skip freezer inspection.

This PR should be followed with a downstream PR in Coreth to pass in an
option to skip freezer inspection during database inspection.

## How this works

Extends `inspectDatabaseConfig` with a `skipFreezers` field and adds the
associated option function for it.

## How this was tested

CI + ran `InspectDatabase()` against Coreth locally

core/rawdb/ancient_utils.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/ava-labs/libevm/common"
 	"github.com/ava-labs/libevm/ethdb"
+	"github.com/ava-labs/libevm/libevm/options"
 )
 
 type tableSize struct {
@@ -77,7 +78,10 @@ func inspect(name string, order map[string]bool, reader ethdb.AncientReader) (fr
 }
 
 // inspectFreezers inspects all freezers registered in the system.
-func inspectFreezers(db ethdb.Database) ([]freezerInfo, error) {
+func inspectFreezers(db ethdb.Database, opts ...InspectDatabaseOption) ([]freezerInfo, error) {
+	if options.As[inspectDatabaseConfig](opts...).skipFreezers {
+		return nil, nil
+	}
 	var infos []freezerInfo
 	for _, freezer := range freezers {
 		switch freezer {

core/rawdb/database.go

@@ -604,7 +604,7 @@ func InspectDatabase(db ethdb.Database, keyPrefix, keyStart []byte, opts ...Insp
 		{"Light client", "Bloom trie nodes", bloomTrieNodes.Size(), bloomTrieNodes.Count()},
 	}
 	// Inspect all registered append-only file store then.
-	ancients, err := inspectFreezers(db)
+	ancients, err := inspectFreezers(db, opts...)
 	if err != nil {
 		return err
 	}

core/rawdb/database.libevm.go

@@ -28,6 +28,7 @@ type inspectDatabaseConfig struct {
 	statRecorders     []func([]byte, common.StorageSize) bool
 	isMetas           []func([]byte) bool
 	statsTransformers []func([][]string) [][]string
+	skipFreezers      bool
 }
 
 func (c inspectDatabaseConfig) recordStat(key []byte, size common.StorageSize) bool {
@@ -91,3 +92,10 @@ func WithDatabaseStatsTransformer(transform func(rows [][]string) [][]string) In
 		c.statsTransformers = append(c.statsTransformers, transform)
 	})
 }
+
+// WithSkipFreezers returns an option that causes for freezer inspection to be skipped.
+func WithSkipFreezers() InspectDatabaseOption {
+	return newInspectOpt(func(c *inspectDatabaseConfig) {
+		c.skipFreezers = true
+	})
+}

core/rawdb/database.libevm_test.go

@@ -20,6 +20,9 @@ import (
 	"bytes"
 	"fmt"
 	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/require"
 
 	"github.com/ava-labs/libevm/common"
 	// To ensure that all methods are available to importing packages, this test
@@ -28,6 +31,18 @@ import (
 	"github.com/ava-labs/libevm/ethdb"
 )
 
+func TestSkipFreezers(t *testing.T) {
+	require := require.New(t)
+	db := rawdb.NewMemoryDatabase()
+
+	var (
+		keyPrefix []byte
+		keyStart  []byte
+	)
+
+	require.NoError(rawdb.InspectDatabase(db, keyPrefix, keyStart, rawdb.WithSkipFreezers()))
+}
+
 // ExampleDatabaseStat demonstrates the method signatures of DatabaseStat, which
 // exposes an otherwise unexported type that won't have its methods documented.
 func ExampleDatabaseStat() {