refactor!: type paramed Header interface

header.go

@@ -6,12 +6,14 @@ import (
 )
 
 // Header abstracts all methods required to perform header sync.
-type Header interface {
+// TODO: Ideally, this should be Header[H Header[H]], but GO does not support recursive type
+// definitions (yet?)
+type Header[H any] interface {
 	// New creates new instance of a header.
 	// It exists to overcome limitation of Go's type system.
 	// See:
 	//https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md#pointer-method-example
-	New() Header
+	New() H
 	// IsZero reports whether Header is a zero value of it's concrete type.
 	IsZero() bool
 	// ChainID returns identifier of the chain.
@@ -25,7 +27,7 @@ type Header interface {
 	// Time returns time when header was created.
 	Time() time.Time
 	// Verify validates given untrusted Header against trusted Header.
-	Verify(Header) error
+	Verify(H) error
 	// Validate performs stateless validation to check for missed/incorrect fields.
 	Validate() error
 
@@ -34,6 +36,6 @@ type Header interface {
 }
 
 // New is a generic Header constructor.
-func New[H Header]() (h H) {
-	return h.New().(H)
+func New[H Header[H]]() (h H) {
+	return h.New()
 }

headertest/dummy_header.go

@@ -44,7 +44,7 @@ func RandDummyHeader(t *testing.T) *DummyHeader {
 	return dh
 }
 
-func (d *DummyHeader) New() header.Header {
+func (d *DummyHeader) New() *DummyHeader {
 	return new(DummyHeader)
 }
 
@@ -96,8 +96,8 @@ func (d *DummyHeader) IsExpired(period time.Duration) bool {
 	return expirationTime.Before(time.Now())
 }
 
-func (d *DummyHeader) Verify(header header.Header) error {
-	if dummy, _ := header.(*DummyHeader); dummy.VerifyFailure {
+func (d *DummyHeader) Verify(header *DummyHeader) error {
+	if header.VerifyFailure {
 		return ErrDummyVerify
 	}
 

headertest/store.go

@@ -8,11 +8,11 @@ import (
 	"github.com/celestiaorg/go-header"
 )
 
-type Generator[H header.Header] interface {
+type Generator[H header.Header[H]] interface {
 	NextHeader() H
 }
 
-type Store[H header.Header] struct {
+type Store[H header.Header[H]] struct {
 	Headers    map[int64]H
 	HeadHeight int64
 }
@@ -23,7 +23,7 @@ func NewDummyStore(t *testing.T) *Store[*DummyHeader] {
 }
 
 // NewStore creates a generic mock store supporting different type of Headers based on Generator.
-func NewStore[H header.Header](t *testing.T, gen Generator[H], numHeaders int) *Store[H] {
+func NewStore[H header.Header[H]](t *testing.T, gen Generator[H], numHeaders int) *Store[H] {
 	store := &Store[H]{
 		Headers:    make(map[int64]H),
 		HeadHeight: 0,
@@ -48,7 +48,7 @@ func (m *Store[H]) Height() uint64 {
 	return uint64(m.HeadHeight)
 }
 
-func (m *Store[H]) Head(context.Context, ...header.HeadOption) (H, error) {
+func (m *Store[H]) Head(context.Context, ...header.HeadOption[H]) (H, error) {
 	return m.Headers[m.HeadHeight], nil
 }
 

headertest/subscriber.go

@@ -6,7 +6,7 @@ import (
 	"github.com/celestiaorg/go-header"
 )
 
-type Subscriber[H header.Header] struct {
+type Subscriber[H header.Header[H]] struct {
 	Headers []H
 }
 

interface.go

@@ -16,7 +16,7 @@ const (
 // Subscriber encompasses the behavior necessary to
 // subscribe/unsubscribe from new Header events from the
 // network.
-type Subscriber[H Header] interface {
+type Subscriber[H Header[H]] interface {
 	// Subscribe creates long-living Subscription for validated Headers.
 	// Multiple Subscriptions can be created.
 	Subscribe() (Subscription[H], error)
@@ -28,7 +28,7 @@ type Subscriber[H Header] interface {
 }
 
 // Subscription listens for new Headers.
-type Subscription[H Header] interface {
+type Subscription[H Header[H]] interface {
 	// NextHeader returns the newest verified and valid Header
 	// in the network.
 	NextHeader(ctx context.Context) (H, error)
@@ -37,13 +37,13 @@ type Subscription[H Header] interface {
 }
 
 // Broadcaster broadcasts a Header to the network.
-type Broadcaster[H Header] interface {
+type Broadcaster[H Header[H]] interface {
 	Broadcast(ctx context.Context, header H, opts ...pubsub.PubOpt) error
 }
 
 // Exchange encompasses the behavior necessary to request Headers
 // from the network.
-type Exchange[H Header] interface {
+type Exchange[H Header[H]] interface {
 	Getter[H]
 }
 
@@ -71,7 +71,7 @@ func (ena *ErrNonAdjacent) Error() string {
 
 // Store encompasses the behavior necessary to store and retrieve Headers
 // from a node's local storage.
-type Store[H Header] interface {
+type Store[H Header[H]] interface {
 	// Start starts the store.
 	Start(context.Context) error
 
@@ -104,7 +104,7 @@ type Store[H Header] interface {
 
 // Getter contains the behavior necessary for a component to retrieve
 // headers that have been processed during header sync.
-type Getter[H Header] interface {
+type Getter[H Header[H]] interface {
 	Head[H]
 
 	// Get returns the Header corresponding to the given hash.
@@ -124,7 +124,7 @@ type Getter[H Header] interface {
 // Head contains the behavior necessary for a component to retrieve
 // the chain head. Note that "chain head" is subjective to the component
 // reporting it.
-type Head[H Header] interface {
+type Head[H Header[H]] interface {
 	// Head returns the latest known header.
-	Head(context.Context, ...HeadOption) (H, error)
+	Head(context.Context, ...HeadOption[H]) (H, error)
 }

local/exchange.go

@@ -7,12 +7,12 @@ import (
 )
 
 // Exchange is a simple Exchange that reads Headers from Store without any networking.
-type Exchange[H header.Header] struct {
+type Exchange[H header.Header[H]] struct {
 	store header.Store[H]
 }
 
 // NewExchange creates a new local Exchange.
-func NewExchange[H header.Header](store header.Store[H]) header.Exchange[H] {
+func NewExchange[H header.Header[H]](store header.Store[H]) header.Exchange[H] {
 	return &Exchange[H]{
 		store: store,
 	}
@@ -26,7 +26,7 @@ func (l *Exchange[H]) Stop(context.Context) error {
 	return nil
 }
 
-func (l *Exchange[H]) Head(ctx context.Context, _ ...header.HeadOption) (H, error) {
+func (l *Exchange[H]) Head(ctx context.Context, _ ...header.HeadOption[H]) (H, error) {
 	return l.store.Head(ctx)
 }
 

metrics.go

@@ -12,7 +12,7 @@ import (
 var meter = otel.Meter("header")
 
 // WithMetrics enables Otel metrics to monitor head and total amount of synced headers.
-func WithMetrics[H Header](store Store[H]) error {
+func WithMetrics[H Header[H]](store Store[H]) error {
 	headC, _ := meter.Int64ObservableCounter(
 		"head",
 		metric.WithDescription("Subjective head of the node"),

opts.go

@@ -1,17 +1,17 @@
 package header
 
-type HeadOption func(opts *HeadParams)
+type HeadOption[H Header[H]] func(opts *HeadParams[H])
 
 // HeadParams contains options to be used for Head interface methods
-type HeadParams struct {
+type HeadParams[H Header[H]] struct {
 	// TrustedHead allows the caller of Head to specify a trusted header
 	// against which the underlying implementation of Head can verify against.
-	TrustedHead Header
+	TrustedHead Header[H]
 }
 
 // WithTrustedHead sets the TrustedHead parameter to the given header.
-func WithTrustedHead(verified Header) func(opts *HeadParams) {
-	return func(opts *HeadParams) {
+func WithTrustedHead[H Header[H]](verified Header[H]) func(opts *HeadParams[H]) {
+	return func(opts *HeadParams[H]) {
 		opts.TrustedHead = verified
 	}
 }

p2p/exchange.go

@@ -32,7 +32,7 @@ var maxUntrustedHeadRequests = 4
 
 // Exchange enables sending outbound HeaderRequests to the network as well as
 // handling inbound HeaderRequests from the network.
-type Exchange[H header.Header] struct {
+type Exchange[H header.Header[H]] struct {
 	ctx    context.Context
 	cancel context.CancelFunc
 
@@ -47,7 +47,7 @@ type Exchange[H header.Header] struct {
 	metrics *metrics
 }
 
-func NewExchange[H header.Header](
+func NewExchange[H header.Header[H]](
 	host host.Host,
 	peers peer.IDSlice,
 	gater *conngater.BasicConnectionGater,
@@ -100,7 +100,7 @@ func (ex *Exchange[H]) Stop(ctx context.Context) error {
 // The Head must be verified thereafter where possible.
 // We request in parallel all the trusted peers, compare their response
 // and return the highest one.
-func (ex *Exchange[H]) Head(ctx context.Context, opts ...header.HeadOption) (H, error) {
+func (ex *Exchange[H]) Head(ctx context.Context, opts ...header.HeadOption[H]) (H, error) {
 	log.Debug("requesting head")
 
 	reqCtx := ctx
@@ -115,7 +115,7 @@ func (ex *Exchange[H]) Head(ctx context.Context, opts ...header.HeadOption) (H,
 		defer cancel()
 	}
 
-	reqParams := header.HeadParams{}
+	reqParams := header.HeadParams[H]{}
 	for _, opt := range opts {
 		opt(&reqParams)
 	}
@@ -344,7 +344,7 @@ func shufflePeers(peers peer.IDSlice) peer.IDSlice {
 // * should be received at least from 2 peers;
 // If neither condition is met, then latest Header will be returned (header of the highest
 // height).
-func bestHead[H header.Header](result []H) (H, error) {
+func bestHead[H header.Header[H]](result []H) (H, error) {
 	if len(result) == 0 {
 		var zero H
 		return zero, header.ErrNotFound

p2p/exchange_test.go

@@ -52,7 +52,7 @@ func TestExchange_RequestHead(t *testing.T) {
 
 	tests := []struct {
 		requestFromTrusted bool
-		lastHeader         header.Header
+		lastHeader         header.Header[*headertest.DummyHeader]
 		expectedHeight     int64
 		expectedHash       header.Hash
 	}{
@@ -74,7 +74,7 @@ func TestExchange_RequestHead(t *testing.T) {
 
 	for i, tt := range tests {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			var opts []header.HeadOption
+			var opts []header.HeadOption[*headertest.DummyHeader]
 			if !tt.requestFromTrusted {
 				opts = append(opts, header.WithTrustedHead(tt.lastHeader))
 			}
@@ -583,7 +583,7 @@ func (t *timedOutStore) HasAt(_ context.Context, _ uint64) bool {
 	return true
 }
 
-func (t *timedOutStore) Head(context.Context, ...header.HeadOption) (*headertest.DummyHeader, error) {
+func (t *timedOutStore) Head(context.Context, ...header.HeadOption[*headertest.DummyHeader]) (*headertest.DummyHeader, error) {
 	time.Sleep(t.timeout)
 	return nil, header.ErrNoHead
 }

p2p/server.go

@@ -25,7 +25,7 @@ var (
 
 // ExchangeServer represents the server-side component for
 // responding to inbound header-related requests.
-type ExchangeServer[H header.Header] struct {
+type ExchangeServer[H header.Header[H]] struct {
 	protocolID protocol.ID
 
 	host  host.Host
@@ -39,7 +39,7 @@ type ExchangeServer[H header.Header] struct {
 
 // NewExchangeServer returns a new P2P server that handles inbound
 // header-related requests.
-func NewExchangeServer[H header.Header](
+func NewExchangeServer[H header.Header[H]](
 	host host.Host,
 	store header.Store[H],
 	opts ...Option[ServerParameters],

p2p/session.go

@@ -18,17 +18,17 @@ import (
 // response.
 var errEmptyResponse = errors.New("empty response")
 
-type option[H header.Header] func(*session[H])
+type option[H header.Header[H]] func(*session[H])
 
-func withValidation[H header.Header](from H) option[H] {
+func withValidation[H header.Header[H]](from H) option[H] {
 	return func(s *session[H]) {
 		s.from = from
 	}
 }
 
 // session aims to divide a range of headers
 // into several smaller requests among different peers.
-type session[H header.Header] struct {
+type session[H header.Header[H]] struct {
 	host       host.Host
 	protocolID protocol.ID
 	queue      *peerQueue
@@ -45,7 +45,7 @@ type session[H header.Header] struct {
 	reqCh  chan *p2p_pb.HeaderRequest
 }
 
-func newSession[H header.Header](
+func newSession[H header.Header[H]](
 	ctx context.Context,
 	h host.Host,
 	peerTracker *peerTracker,
@@ -284,7 +284,7 @@ func prepareRequests(from, amount, headersPerPeer uint64) []*p2p_pb.HeaderReques
 }
 
 // processResponses converts HeaderResponses to Headers
-func processResponses[H header.Header](resps []*p2p_pb.HeaderResponse) ([]H, error) {
+func processResponses[H header.Header[H]](resps []*p2p_pb.HeaderResponse) ([]H, error) {
 	if len(resps) == 0 {
 		return nil, errEmptyResponse
 	}

p2p/subscriber.go

@@ -13,7 +13,7 @@ import (
 
 // Subscriber manages the lifecycle and relationship of header Module
 // with the "header-sub" gossipsub topic.
-type Subscriber[H header.Header] struct {
+type Subscriber[H header.Header[H]] struct {
 	pubsubTopicID string
 
 	pubsub *pubsub.PubSub
@@ -23,7 +23,7 @@ type Subscriber[H header.Header] struct {
 
 // NewSubscriber returns a Subscriber that manages the header Module's
 // relationship with the "header-sub" gossipsub topic.
-func NewSubscriber[H header.Header](
+func NewSubscriber[H header.Header[H]](
 	ps *pubsub.PubSub,
 	msgID pubsub.MsgIdFunction,
 	networkID string,

p2p/subscription.go

@@ -11,14 +11,14 @@ import (
 )
 
 // subscription handles retrieving Headers from the header pubsub topic.
-type subscription[H header.Header] struct {
+type subscription[H header.Header[H]] struct {
 	topic        *pubsub.Topic
 	subscription *pubsub.Subscription
 }
 
 // newSubscription creates a new Header event subscription
 // on the given host.
-func newSubscription[H header.Header](topic *pubsub.Topic) (*subscription[H], error) {
+func newSubscription[H header.Header[H]](topic *pubsub.Topic) (*subscription[H], error) {
 	sub, err := topic.Subscribe()
 	if err != nil {
 		return nil, err

store/batch.go

@@ -13,14 +13,14 @@ import (
 // unlike the Store which keeps 'hash -> header' and 'height -> hash'.
 // The approach simplifies implementation for the batch and
 // makes it better optimized for the GetByHeight case which is what we need.
-type batch[H header.Header] struct {
+type batch[H header.Header[H]] struct {
 	lk      sync.RWMutex
 	heights map[string]uint64
 	headers []H
 }
 
 // newBatch creates the batch with the given pre-allocated size.
-func newBatch[H header.Header](size int) *batch[H] {
+func newBatch[H header.Header[H]](size int) *batch[H] {
 	return &batch[H]{
 		heights: make(map[string]uint64, size),
 		headers: make([]H, 0, size),