cleanups and fix example

examples/gateway/graph/main.go

@@ -27,13 +27,13 @@ func main() {
 	}
 	defer (func() { _ = tp.Shutdown(ctx) })()
 
-	carFetcher, err := gateway.NewRemoteCarFetcher([]string{*gatewayUrlPtr}, nil)
+	carFetcher, err := gateway.NewRemoteCarFetcher([]string{*gatewayUrlPtr})
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	// Creates the gateway with the remote graph backend.
-	backend, err := gateway.NewGraphGatewayBackend(carFetcher)
+	backend, err := gateway.NewGraphBackend(carFetcher)
 	if err != nil {
 		log.Fatal(err)
 	}

gateway/backend.go

@@ -10,11 +10,56 @@ import (
 	"github.com/ipfs/boxo/ipns"
 	"github.com/ipfs/boxo/namesys"
 	"github.com/ipfs/boxo/path"
+	"github.com/ipfs/boxo/path/resolver"
 	"github.com/ipfs/go-cid"
 	routinghelpers "github.com/libp2p/go-libp2p-routing-helpers"
 	"github.com/libp2p/go-libp2p/core/routing"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
+type backendOptions struct {
+	ns           namesys.NameSystem
+	vs           routing.ValueStore
+	r            resolver.Resolver
+	promRegistry prometheus.Registerer
+}
+
+// WithNameSystem sets the name system to use with the different backends. If not set
+// it will use the default DNSLink resolver generated by [NewDNSResolver] along
+// with any configured [routing.ValueStore].
+func WithNameSystem(ns namesys.NameSystem) BackendOption {
+	return func(opts *backendOptions) error {
+		opts.ns = ns
+		return nil
+	}
+}
+
+// WithValueStore sets the [routing.ValueStore] to use with the different backends.
+func WithValueStore(vs routing.ValueStore) BackendOption {
+	return func(opts *backendOptions) error {
+		opts.vs = vs
+		return nil
+	}
+}
+
+// WithResolver sets the [resolver.Resolver] to use with the different backends.
+func WithResolver(r resolver.Resolver) BackendOption {
+	return func(opts *backendOptions) error {
+		opts.r = r
+		return nil
+	}
+}
+
+// WithPrometheusRegistry sets the registry to use with [GraphBackend].
+func WithPrometheusRegistry(reg prometheus.Registerer) BackendOption {
+	return func(opts *backendOptions) error {
+		opts.promRegistry = reg
+		return nil
+	}
+}
+
+type BackendOption func(options *backendOptions) error
+
 // baseBackend contains some common backend functionalities that are shared by
 // different backend implementations.
 type baseBackend struct {

gateway/backend_blocks.go

@@ -16,7 +16,6 @@ import (
 	"github.com/ipfs/boxo/ipld/merkledag"
 	ufile "github.com/ipfs/boxo/ipld/unixfs/file"
 	uio "github.com/ipfs/boxo/ipld/unixfs/io"
-	"github.com/ipfs/boxo/namesys"
 	"github.com/ipfs/boxo/path"
 	"github.com/ipfs/boxo/path/resolver"
 	blocks "github.com/ipfs/go-block-format"
@@ -35,9 +34,7 @@ import (
 	"github.com/ipld/go-ipld-prime/traversal"
 	"github.com/ipld/go-ipld-prime/traversal/selector"
 	selectorparse "github.com/ipld/go-ipld-prime/traversal/selector/parse"
-	"github.com/libp2p/go-libp2p/core/routing"
 	mc "github.com/multiformats/go-multicodec"
-	"github.com/prometheus/client_golang/prometheus"
 
 	// Ensure basic codecs are registered.
 	_ "github.com/ipld/go-ipld-prime/codec/cbor"
@@ -57,51 +54,8 @@ type BlocksBackend struct {
 
 var _ IPFSBackend = (*BlocksBackend)(nil)
 
-type blocksBackendOptions struct {
-	ns           namesys.NameSystem
-	vs           routing.ValueStore
-	r            resolver.Resolver
-	promRegistry prometheus.Registerer
-}
-
-// WithNameSystem sets the name system to use with the [BlocksBackend]. If not set
-// it will use the default DNSLink resolver generated by [NewDNSResolver] along
-// with any configured [routing.ValueStore].
-func WithNameSystem(ns namesys.NameSystem) BlocksBackendOption {
-	return func(opts *blocksBackendOptions) error {
-		opts.ns = ns
-		return nil
-	}
-}
-
-// WithValueStore sets the [routing.ValueStore] to use with the [BlocksBackend].
-func WithValueStore(vs routing.ValueStore) BlocksBackendOption {
-	return func(opts *blocksBackendOptions) error {
-		opts.vs = vs
-		return nil
-	}
-}
-
-// WithResolver sets the [resolver.Resolver] to use with the [BlocksBackend].
-func WithResolver(r resolver.Resolver) BlocksBackendOption {
-	return func(opts *blocksBackendOptions) error {
-		opts.r = r
-		return nil
-	}
-}
-
-// WithPrometheusRegistry sets the registry to use for metrics collection.
-func WithPrometheusRegistry(reg prometheus.Registerer) BlocksBackendOption {
-	return func(opts *blocksBackendOptions) error {
-		opts.promRegistry = reg
-		return nil
-	}
-}
-
-type BlocksBackendOption func(options *blocksBackendOptions) error
-
-func NewBlocksBackend(blockService blockservice.BlockService, opts ...BlocksBackendOption) (*BlocksBackend, error) {
-	var compiledOptions blocksBackendOptions
+func NewBlocksBackend(blockService blockservice.BlockService, opts ...BackendOption) (*BlocksBackend, error) {
+	var compiledOptions backendOptions
 	for _, o := range opts {
 		if err := o(&compiledOptions); err != nil {
 			return nil, err