refactor: add MountedLink to bind transport to link

Signed-off-by: Christian Stewart <christian@aperture.us>

Author: paralin

link/establish-link-ex.go

@@ -15,13 +15,11 @@ func EstablishLinkWithPeerEx(
 	b bus.Bus,
 	localPeerID, remotePeerID peer.ID,
 	returnIfIdle bool,
-) (Link, func(), error) {
+) (EstablishLinkWithPeerValue, func(), error) {
 	estl, _, ref, err := bus.ExecWaitValue[EstablishLinkWithPeerValue](
 		ctx,
 		b,
-		NewEstablishLinkWithPeer(
-			localPeerID, remotePeerID,
-		),
+		NewEstablishLinkWithPeer(localPeerID, remotePeerID),
 		bus.ReturnIfIdle(returnIfIdle),
 		nil,
 		nil,

link/establish-link.go

@@ -27,7 +27,7 @@ type EstablishLinkWithPeer interface {
 }
 
 // EstablishLinkWithPeerValue is the type emitted when resolving EstablishLinkWithPeer.
-type EstablishLinkWithPeerValue = Link
+type EstablishLinkWithPeerValue = MountedLink
 
 // establishLinkWithPeer implements EstablishLinkWithPeer with a peer ID constraint.
 type establishLinkWithPeer struct {

link/mounted-link.go

@@ -0,0 +1,34 @@
+package link
+
+import (
+	"context"
+
+	"github.com/aperturerobotics/bifrost/peer"
+	"github.com/aperturerobotics/bifrost/protocol"
+	"github.com/aperturerobotics/bifrost/stream"
+)
+
+// MountedLink is a Link managed by the transport controller.
+type MountedLink interface {
+	// GetLinkUUID returns the host-unique link ID.
+	// This should be repeatable between re-constructions of the same link.
+	GetLinkUUID() uint64
+
+	// GetTransportUUID returns the unique ID of the transport.
+	GetTransportUUID() uint64
+	// GetRemoteTransportUUID returns the reported remote transport UUID.
+	// This should be negotiated in the handshake.
+	GetRemoteTransportUUID() uint64
+
+	// GetLocalPeer returns the identity of the local peer.
+	GetLocalPeer() peer.ID
+	// GetRemotePeer returns the identity of the remote peer.
+	GetRemotePeer() peer.ID
+
+	// OpenMountedStream opens a stream on the link, with the given parameters.
+	OpenMountedStream(
+		ctx context.Context,
+		protocolID protocol.ID,
+		opts stream.OpenOpts,
+	) (MountedStream, error)
+}

link/mounted-stream.go

@@ -22,7 +22,7 @@ type MountedStream interface {
 	// GetPeerID returns the peer ID for the other end of the stream.
 	GetPeerID() peer.ID
 	// GetLink returns the associated link carrying the stream.
-	GetLink() Link
+	GetLink() MountedLink
 }
 
 // MountedStreamHandler handles an incoming mounted stream.

link/open-stream-ex.go

@@ -10,7 +10,7 @@ import (
 )
 
 // OpenStreamWithPeerEx executes a OpenStreamWithPeer directive.
-// Returns a release function for the links used for the stream.
+// Returns a release function for the reference to the link used for the stream.
 func OpenStreamWithPeerEx(
 	ctx context.Context,
 	b bus.Bus,
@@ -19,32 +19,26 @@ func OpenStreamWithPeerEx(
 	transportID uint64,
 	openOpts stream.OpenOpts,
 ) (MountedStream, func(), error) {
-	_, estLinkRef, err := b.AddDirective(
+	mlnk, _, ref, err := bus.ExecWaitValue[EstablishLinkWithPeerValue](
+		ctx,
+		b,
 		NewEstablishLinkWithPeer(localPeerID, remotePeerID),
 		nil,
+		nil,
+		nil,
 	)
 	if err != nil {
+		if ref != nil {
+			ref.Release()
+		}
 		return nil, func() {}, err
 	}
 
-	mstrm, _, ref, err := bus.ExecWaitValue[MountedStream](
-		ctx,
-		b,
-		NewOpenStreamWithPeer(
-			protocolID,
-			localPeerID, remotePeerID,
-			transportID,
-			openOpts,
-		),
-		nil,
-		nil,
-		nil,
-	)
+	mstrm, err := mlnk.OpenMountedStream(ctx, protocolID, openOpts)
 	if err != nil {
-		estLinkRef.Release()
+		ref.Release()
 		return nil, func() {}, err
 	}
-	ref.Release()
 
-	return mstrm, estLinkRef.Release, nil
+	return mstrm, ref.Release, nil
 }