op-challenger: Find snapshot to start execution at

op-challenger/fault/cannon/cannon_provider.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/ethereum-optimism/optimism/op-challenger/config"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/log"
@@ -22,20 +23,20 @@ type proofData struct {
 	ProofData  hexutil.Bytes `json:"proof-data"`
 }
 
-type Executor interface {
+type ProofGenerator interface {
 	// GenerateProof executes cannon to generate a proof at the specified trace index in dataDir.
 	GenerateProof(dataDir string, proofAt uint64) error
 }
 
 type CannonTraceProvider struct {
-	dir      string
-	executor Executor
+	dir       string
+	generator ProofGenerator
 }
 
-func NewCannonTraceProvider(logger log.Logger, dataDir string) *CannonTraceProvider {
+func NewCannonTraceProvider(logger log.Logger, cfg *config.Config) *CannonTraceProvider {
 	return &CannonTraceProvider{
-		dir:      dataDir,
-		executor: newExecutor(logger),
+		dir:       cfg.CannonDatadir,
+		generator: NewExecutor(logger, cfg),
 	}
 }
 
@@ -76,7 +77,7 @@ func (p *CannonTraceProvider) loadProof(i uint64) (*proofData, error) {
 	path := filepath.Join(p.dir, proofsDir, fmt.Sprintf("%d.json", i))
 	file, err := os.Open(path)
 	if errors.Is(err, os.ErrNotExist) {
-		if err := p.executor.GenerateProof(p.dir, i); err != nil {
+		if err := p.generator.GenerateProof(p.dir, i); err != nil {
 			return nil, fmt.Errorf("generate cannon trace with proof at %v: %w", i, err)
 		}
 		// Try opening the file again now and it should exist.

op-challenger/fault/cannon/cannon_provider_test.go

@@ -17,73 +17,73 @@ var testData embed.FS
 func TestGet(t *testing.T) {
 	dataDir := setupTestData(t)
 	t.Run("ExistingProof", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		value, err := provider.Get(0)
 		require.NoError(t, err)
 		require.Equal(t, common.HexToHash("0x45fd9aa59768331c726e719e76aa343e73123af888804604785ae19506e65e87"), value)
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 
 	t.Run("ProofUnavailable", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		_, err := provider.Get(7)
 		require.ErrorIs(t, err, os.ErrNotExist)
-		require.Contains(t, executor.generated, 7, "should have tried to generate the proof")
+		require.Contains(t, generator.generated, 7, "should have tried to generate the proof")
 	})
 
 	t.Run("MissingPostHash", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		_, err := provider.Get(1)
 		require.ErrorContains(t, err, "missing post hash")
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 
 	t.Run("IgnoreUnknownFields", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		value, err := provider.Get(2)
 		require.NoError(t, err)
 		expected := common.HexToHash("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb")
 		require.Equal(t, expected, value)
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 }
 
 func TestGetPreimage(t *testing.T) {
 	dataDir := setupTestData(t)
 	t.Run("ExistingProof", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		value, proof, err := provider.GetPreimage(0)
 		require.NoError(t, err)
 		expected := common.Hex2Bytes("b8f068de604c85ea0e2acd437cdb47add074a2d70b81d018390c504b71fe26f400000000000000000000000000000000000000000000000000000000000000000000000000")
 		require.Equal(t, expected, value)
 		expectedProof := common.Hex2Bytes("08028e3c0000000000000000000000003c01000a24210b7c00200008000000008fa40004")
 		require.Equal(t, expectedProof, proof)
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 
 	t.Run("ProofUnavailable", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		_, _, err := provider.GetPreimage(7)
 		require.ErrorIs(t, err, os.ErrNotExist)
-		require.Contains(t, executor.generated, 7, "should have tried to generate the proof")
+		require.Contains(t, generator.generated, 7, "should have tried to generate the proof")
 	})
 
 	t.Run("MissingStateData", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		_, _, err := provider.GetPreimage(1)
 		require.ErrorContains(t, err, "missing state data")
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 
 	t.Run("IgnoreUnknownFields", func(t *testing.T) {
-		provider, executor := setupWithTestData(dataDir)
+		provider, generator := setupWithTestData(dataDir)
 		value, proof, err := provider.GetPreimage(2)
 		require.NoError(t, err)
 		expected := common.Hex2Bytes("cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc")
 		require.Equal(t, expected, value)
 		expectedProof := common.Hex2Bytes("dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd")
 		require.Equal(t, expectedProof, proof)
-		require.Empty(t, executor.generated)
+		require.Empty(t, generator.generated)
 	})
 }
 
@@ -103,19 +103,19 @@ func setupTestData(t *testing.T) string {
 	return dataDir
 }
 
-func setupWithTestData(dataDir string) (*CannonTraceProvider, *stubExecutor) {
-	executor := &stubExecutor{}
+func setupWithTestData(dataDir string) (*CannonTraceProvider, *stubGenerator) {
+	generator := &stubGenerator{}
 	return &CannonTraceProvider{
-		dir:      dataDir,
-		executor: executor,
-	}, executor
+		dir:       dataDir,
+		generator: generator,
+	}, generator
 }
 
-type stubExecutor struct {
+type stubGenerator struct {
 	generated []int // Using int makes assertions easier
 }
 
-func (e *stubExecutor) GenerateProof(dir string, i uint64) error {
+func (e *stubGenerator) GenerateProof(dir string, i uint64) error {
 	e.generated = append(e.generated, int(i))
 	return nil
 }

op-challenger/fault/cannon/executor.go

 package cannon
 
 import (
+	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
 
+	"github.com/ethereum-optimism/optimism/op-challenger/config"
 	"github.com/ethereum/go-ethereum/log"
 )
 
-type executor struct {
-	logger log.Logger
+const snapsDir = "snapshots"
+
+var snapshotNameRegexp = regexp.MustCompile(`^[0-9]+\.json$`)
+
+const snapshotFrequency = 10_000
+
+type snapshotSelect func(logger log.Logger, dir string, absolutePreState string, i uint64) (string, error)
+
+type Executor struct {
+	logger           log.Logger
+	l1               string
+	l2               string
+	cannon           string
+	absolutePreState string
+	dataDir          string
+	selectSnapshot   snapshotSelect
 }
 
-func newExecutor(logger log.Logger) Executor {
-	return &executor{
-		logger: logger,
+func NewExecutor(logger log.Logger, cfg *config.Config) *Executor {
+	return &Executor{
+		logger:           logger,
+		l1:               cfg.L1EthRpc,
+		l2:               cfg.CannonL2,
+		cannon:           cfg.CannonBin,
+		absolutePreState: cfg.CannonAbsolutePreState,
+		dataDir:          cfg.CannonDatadir,
+		selectSnapshot:   findStartingSnapshot,
 	}
 }
 
-func (e *executor) GenerateProof(dir string, i uint64) error {
-	return fmt.Errorf("please execute cannon with --proof-at %v --proof-fmt %v/%v/%%d.json", i, dir, proofsDir)
+func (e *Executor) GenerateProof(dir string, i uint64) error {
+	start, err := e.selectSnapshot(e.logger, filepath.Join(e.dataDir, snapsDir), e.absolutePreState, i)
+	if err != nil {
+		return fmt.Errorf("find starting snapshot: %w", err)
+	}
+	return fmt.Errorf("please execute cannon with --input %v --proof-at %v --proof-fmt %v/%v/%%d.json --snapshot-at %%%d --snapshot-fmt '%v/%v/%%d.json",
+		start, i, dir, proofsDir, snapshotFrequency, dir, snapsDir)
+}
+
+// findStartingSnapshot finds the closest snapshot before the specified traceIndex in snapDir.
+// If no suitable snapshot can be found it returns absolutePreState.
+func findStartingSnapshot(logger log.Logger, snapDir string, absolutePreState string, traceIndex uint64) (string, error) {
+	// Find the closest snapshot to start from
+	entries, err := os.ReadDir(snapDir)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return absolutePreState, nil
+		}
+		return "", fmt.Errorf("list snapshots in %v: %w", snapDir, err)
+	}
+	bestSnap := uint64(0)
+	for _, entry := range entries {
+		if entry.IsDir() {
+			logger.Warn("Unexpected directory in snapshots dir: %v/%v", snapDir, entry.Name())
+			continue
+		}
+		name := entry.Name()
+		if !snapshotNameRegexp.MatchString(name) {
+			logger.Warn("Unexpected file in snapshots dir: %v/%v", snapDir, entry.Name())
+			continue
+		}
+		index, err := strconv.ParseUint(name[0:len(name)-len(".json")], 10, 64)
+		if err != nil {
+			logger.Error("Unable to parse trace index of snapshot file: %v/%v", snapDir, entry.Name())
+			continue
+		}
+		if index > bestSnap && index < traceIndex {
+			bestSnap = index
+		}
+	}
+	if bestSnap == 0 {
+		return absolutePreState, nil
+	}
+	startFrom := fmt.Sprintf("%v/%v.json", snapDir, bestSnap)
+
+	return startFrom, nil
 }

op-challenger/fault/cannon/executor_test.go

+package cannon
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/ethereum-optimism/optimism/op-node/testlog"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/stretchr/testify/require"
+)
+
+const execTestCannonPrestate = "/foo/pre.json"
+
+func TestFindStartingSnapshot(t *testing.T) {
+	logger := testlog.Logger(t, log.LvlInfo)
+
+	withSnapshots := func(t *testing.T, files ...string) string {
+		dir := t.TempDir()
+		for _, file := range files {
+			require.NoError(t, os.WriteFile(fmt.Sprintf("%v/%v", dir, file), nil, 0o644))
+		}
+		return dir
+	}
+
+	t.Run("UsePrestateWhenSnapshotsDirDoesNotExist", func(t *testing.T) {
+		dir := t.TempDir()
+		snapshot, err := findStartingSnapshot(logger, filepath.Join(dir, "doesNotExist"), execTestCannonPrestate, 1200)
+		require.NoError(t, err)
+		require.Equal(t, execTestCannonPrestate, snapshot)
+	})
+
+	t.Run("UsePrestateWhenSnapshotsDirEmpty", func(t *testing.T) {
+		dir := withSnapshots(t)
+		snapshot, err := findStartingSnapshot(logger, dir, execTestCannonPrestate, 1200)
+		require.NoError(t, err)
+		require.Equal(t, execTestCannonPrestate, snapshot)
+	})
+
+	t.Run("UsePrestateWhenNoSnapshotBeforeTraceIndex", func(t *testing.T) {
+		dir := withSnapshots(t, "100.json", "200.json")
+		snapshot, err := findStartingSnapshot(logger, dir, execTestCannonPrestate, 99)
+		require.NoError(t, err)
+		require.Equal(t, execTestCannonPrestate, snapshot)
+
+		snapshot, err = findStartingSnapshot(logger, dir, execTestCannonPrestate, 100)
+		require.NoError(t, err)
+		require.Equal(t, execTestCannonPrestate, snapshot)
+	})
+
+	t.Run("UseClosestAvailableSnapshot", func(t *testing.T) {
+		dir := withSnapshots(t, "100.json", "123.json", "250.json")
+
+		snapshot, err := findStartingSnapshot(logger, dir, execTestCannonPrestate, 101)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "100.json"), snapshot)
+
+		snapshot, err = findStartingSnapshot(logger, dir, execTestCannonPrestate, 123)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "100.json"), snapshot)
+
+		snapshot, err = findStartingSnapshot(logger, dir, execTestCannonPrestate, 124)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "123.json"), snapshot)
+
+		snapshot, err = findStartingSnapshot(logger, dir, execTestCannonPrestate, 256)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "250.json"), snapshot)
+	})
+
+	t.Run("IgnoreDirectories", func(t *testing.T) {
+		dir := withSnapshots(t, "100.json")
+		require.NoError(t, os.Mkdir(filepath.Join(dir, "120.json"), 0o777))
+		snapshot, err := findStartingSnapshot(logger, dir, execTestCannonPrestate, 150)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "100.json"), snapshot)
+	})
+
+	t.Run("IgnoreUnexpectedFiles", func(t *testing.T) {
+		dir := withSnapshots(t, ".file", "100.json", "foo", "bar.json")
+		snapshot, err := findStartingSnapshot(logger, dir, execTestCannonPrestate, 150)
+		require.NoError(t, err)
+		require.Equal(t, filepath.Join(dir, "100.json"), snapshot)
+	})
+}

op-challenger/fault/service.go

@@ -56,7 +56,7 @@ func NewService(ctx context.Context, logger log.Logger, cfg *config.Config) (*se
 	var trace types.TraceProvider
 	switch cfg.TraceType {
 	case config.TraceTypeCannon:
-		trace = cannon.NewCannonTraceProvider(logger, cfg.CannonDatadir)
+		trace = cannon.NewCannonTraceProvider(logger, cfg)
 	case config.TraceTypeAlphabet:
 		trace = alphabet.NewAlphabetProvider(cfg.AlphabetTrace, uint64(cfg.GameDepth))
 	default: