refactor(sync): SyncFromHash as string (#311)

Otherwise, it's ignored by the config toml

Author: Wondertan

sync/options.go

@@ -1,6 +1,7 @@
 package sync
 
 import (
+	"encoding/hex"
 	"fmt"
 	"time"
 
@@ -24,14 +25,16 @@ type Parameters struct {
 	TrustingPeriod time.Duration
 	// PruningWindow defines the duration within which headers are retained before being pruned.
 	PruningWindow time.Duration
-	// SyncFromHash is the hash of the header from which the syncer should start syncing.
+	// SyncFromHash is the hash of the header from which Syncer should start syncing.
+	// Zero value to disable. Value updates up and down the chain are gracefully handled by Syncer.
 	//
 	// By default, Syncer maintains PruningWindow number of headers. SyncFromHash overrides this default,
 	// allowing any user to specify a custom starting point.
 	//
 	// SyncFromHash has higher priority than SyncFromHeight.
-	SyncFromHash header.Hash
-	// SyncFromHeight is the height of the header from which the syncer should start syncing.
+	SyncFromHash string
+	// SyncFromHeight is the height of the header from which Syncer should start syncing.
+	// Zero value to disable. Value updates up and down the chain are gracefully handled by Syncer.
 	//
 	// By default, Syncer maintains PruningWindow number of headers. SyncFromHeight overrides this default,
 	// allowing any user to specify a custom starting point.
@@ -48,6 +51,8 @@ type Parameters struct {
 	recencyThreshold time.Duration
 	// metrics is a flag that enables metrics collection.
 	metrics bool
+	// hash cache
+	hash header.Hash
 }
 
 // DefaultParameters returns the default params to configure the syncer.
@@ -60,11 +65,32 @@ func DefaultParameters() Parameters {
 
 func (p *Parameters) Validate() error {
 	if p.TrustingPeriod == 0 {
-		return fmt.Errorf("invalid trusting period duration: %v", p.TrustingPeriod)
+		return fmt.Errorf("invalid TrustingPeriod duration: %v", p.TrustingPeriod)
+	}
+	if (p.SyncFromHeight == 0 || p.SyncFromHash == "") && p.PruningWindow == 0 {
+		return fmt.Errorf(
+			"PruningWindow duration can't be zero when either of SyncFromHeight or SyncFromHash are not set",
+		)
+	}
+	_, err := p.Hash()
+	if err != nil {
+		return err
 	}
 	return nil
 }
 
+func (p *Parameters) Hash() (header.Hash, error) {
+	if p.hash == nil && len(p.SyncFromHash) > 0 {
+		hash, err := hex.DecodeString(p.SyncFromHash)
+		if err != nil {
+			return nil, fmt.Errorf("invalid SyncFromHash: %w", err)
+		}
+
+		p.hash = hash
+	}
+	return p.hash, nil
+}
+
 // WithMetrics enables Metrics on Syncer.
 func WithMetrics() Option {
 	return func(p *Parameters) {
@@ -105,7 +131,7 @@ func WithParams(params Parameters) Option {
 
 // WithSyncFromHash sets given header hash a starting point for syncing.
 // See [Parameters.SyncFromHash] for details.
-func WithSyncFromHash(hash header.Hash) Option {
+func WithSyncFromHash(hash string) Option {
 	return func(p *Parameters) {
 		p.SyncFromHash = hash
 	}

sync/syncer_tail.go

@@ -47,7 +47,10 @@ func (s *Syncer[H]) subjectiveTail(ctx context.Context, head H) (H, error) {
 
 // renewTail resolves the new actual tail header respecting Syncer parameters.
 func (s *Syncer[H]) renewTail(ctx context.Context, oldTail, head H) (newTail H, err error) {
-	useHash, tailHash := s.tailHash(oldTail)
+	useHash, tailHash, err := s.tailHash(oldTail)
+	if err != nil {
+		return oldTail, err
+	}
 	switch {
 	case useHash:
 		if tailHash == nil {
@@ -101,7 +104,7 @@ func (s *Syncer[H]) renewTail(ctx context.Context, oldTail, head H) (newTail H,
 	}
 
 	if err := s.store.Append(ctx, newTail); err != nil {
-		return newTail, fmt.Errorf("appending tail header: %w", err)
+		return newTail, fmt.Errorf("appending tail header %d: %w", newTail.Height(), err)
 	}
 
 	return newTail, nil
@@ -149,19 +152,22 @@ func (s *Syncer[H]) moveTail(ctx context.Context, from, to H) error {
 
 // tailHash reports whether tail hash should be used and returns it.
 // Returns empty hash if it hasn't changed from the old tail hash.
-func (s *Syncer[H]) tailHash(oldTail H) (bool, header.Hash) {
-	hash := s.Params.SyncFromHash
+func (s *Syncer[H]) tailHash(oldTail H) (bool, header.Hash, error) {
+	hash, err := s.Params.Hash()
+	if err != nil {
+		return false, nil, err
+	}
 	if len(hash) == 0 {
-		return false, nil
+		return false, nil, nil
 	}
 
 	updated := oldTail.IsZero() || !bytes.Equal(hash, oldTail.Hash())
 	if !updated {
-		return true, nil
+		return true, nil, nil
 	}
 
 	log.Debugw("tail hash updated", "hash", hash)
-	return true, hash
+	return true, hash, nil
 }
 
 // tailHeight figures the actual tail height based on the Syncer parameters.

sync/syncer_tail_test.go

@@ -37,7 +37,7 @@ func TestSyncer_TailHashOverHeight(t *testing.T) {
 		localStore,
 		headertest.NewDummySubscriber(),
 		WithBlockTime(headertest.HeaderTime),
-		WithSyncFromHash(startFrom.Hash()),
+		WithSyncFromHash(startFrom.Hash().String()),
 	)
 	require.NoError(t, err)
 
@@ -195,7 +195,7 @@ func TestSyncer_TailInitialization(t *testing.T) {
 		},
 		{
 			"SyncFromHash",
-			WithSyncFromHash(expectedTail.Hash()),
+			WithSyncFromHash(expectedTail.Hash().String()),
 			func() *headertest.DummyHeader {
 				return expectedTail
 			},
@@ -257,8 +257,10 @@ func TestSyncer_TailInitialization(t *testing.T) {
 			err = syncer.Stop(ctx)
 			require.NoError(t, err)
 			expectedTail = test.expectedAfterRestart()
+			params := DefaultParameters()
+			syncer.Params = &params
 			syncer.Params.SyncFromHeight = expectedTail.Height()
-			syncer.Params.SyncFromHash = expectedTail.Hash()
+			syncer.Params.SyncFromHash = expectedTail.Hash().String()
 
 			// simulate new head
 			err = remoteStore.Append(ctx, suite.NextHeader())
@@ -271,7 +273,9 @@ func TestSyncer_TailInitialization(t *testing.T) {
 			// ensure that the Syncer moved to the new tail after restart
 			storeTail, err = localStore.Tail(ctx)
 			require.NoError(t, err)
-			assert.EqualValues(t, expectedTail.Height(), storeTail.Height())
+			assert.EqualValues(t, int(expectedTail.Height()), int(storeTail.Height()))
+			t.Log(expectedTail.Hash().String())
+			t.Log(storeTail.Hash().String())
 		})
 	}
 }