refactor: rename messageSender to peerMessageSender and added comments to...

refactor: rename messageSender to peerMessageSender and added comments to clarify what peerMessageSender and messageManager do

dht.go

@@ -190,7 +190,7 @@ func New(ctx context.Context, h host.Host, options ...Option) (*IpfsDHT, error)
 	dht.Validator = cfg.validator
 	dht.messageMgr = &messageManager{
 		host:      h,
-		strmap:    make(map[peer.ID]*messageSender),
+		strmap:    make(map[peer.ID]*peerMessageSender),
 		protocols: dht.protocols,
 	}
 	dht.protoMessenger, err = pb.NewProtocolMessenger(dht.messageMgr, pb.WithValidator(dht.Validator))

message_manager.go

@@ -19,10 +19,12 @@ import (
 	"go.opencensus.io/tag"
 )
 
+// messageManager is responsible for sending requests and messages to peers efficiently, including reuse of streams.
+// It also tracks metrics for sent requests and messages.
 type messageManager struct {
 	host      host.Host // the network services we need
 	smlk      sync.Mutex
-	strmap    map[peer.ID]*messageSender
+	strmap    map[peer.ID]*peerMessageSender
 	protocols []protocol.ID
 }
 
@@ -111,14 +113,14 @@ func (m *messageManager) SendMessage(ctx context.Context, p peer.ID, pmes *pb.Me
 	return nil
 }
 
-func (m *messageManager) messageSenderForPeer(ctx context.Context, p peer.ID) (*messageSender, error) {
+func (m *messageManager) messageSenderForPeer(ctx context.Context, p peer.ID) (*peerMessageSender, error) {
 	m.smlk.Lock()
 	ms, ok := m.strmap[p]
 	if ok {
 		m.smlk.Unlock()
 		return ms, nil
 	}
-	ms = &messageSender{p: p, m: m, lk: newCtxMutex()}
+	ms = &peerMessageSender{p: p, m: m, lk: newCtxMutex()}
 	m.strmap[p] = ms
 	m.smlk.Unlock()
 
@@ -143,7 +145,8 @@ func (m *messageManager) messageSenderForPeer(ctx context.Context, p peer.ID) (*
 	return ms, nil
 }
 
-type messageSender struct {
+// peerMessageSender is responsible for sending requests and messages to a particular peer
+type peerMessageSender struct {
 	s  network.Stream
 	r  msgio.ReadCloser
 	lk ctxMutex
@@ -154,10 +157,10 @@ type messageSender struct {
 	singleMes int
 }
 
-// invalidate is called before this messageSender is removed from the strmap.
-// It prevents the messageSender from being reused/reinitialized and then
+// invalidate is called before this peerMessageSender is removed from the strmap.
+// It prevents the peerMessageSender from being reused/reinitialized and then
 // forgotten (leaving the stream open).
-func (ms *messageSender) invalidate() {
+func (ms *peerMessageSender) invalidate() {
 	ms.invalid = true
 	if ms.s != nil {
 		_ = ms.s.Reset()
@@ -165,7 +168,7 @@ func (ms *messageSender) invalidate() {
 	}
 }
 
-func (ms *messageSender) prepOrInvalidate(ctx context.Context) error {
+func (ms *peerMessageSender) prepOrInvalidate(ctx context.Context) error {
 	if err := ms.lk.Lock(ctx); err != nil {
 		return err
 	}
@@ -178,7 +181,7 @@ func (ms *messageSender) prepOrInvalidate(ctx context.Context) error {
 	return nil
 }
 
-func (ms *messageSender) prep(ctx context.Context) error {
+func (ms *peerMessageSender) prep(ctx context.Context) error {
 	if ms.invalid {
 		return fmt.Errorf("message sender has been invalidated")
 	}
@@ -205,7 +208,7 @@ func (ms *messageSender) prep(ctx context.Context) error {
 // behaviour.
 const streamReuseTries = 3
 
-func (ms *messageSender) SendMessage(ctx context.Context, pmes *pb.Message) error {
+func (ms *peerMessageSender) SendMessage(ctx context.Context, pmes *pb.Message) error {
 	if err := ms.lk.Lock(ctx); err != nil {
 		return err
 	}
@@ -242,7 +245,7 @@ func (ms *messageSender) SendMessage(ctx context.Context, pmes *pb.Message) erro
 	}
 }
 
-func (ms *messageSender) SendRequest(ctx context.Context, pmes *pb.Message) (*pb.Message, error) {
+func (ms *peerMessageSender) SendRequest(ctx context.Context, pmes *pb.Message) (*pb.Message, error) {
 	if err := ms.lk.Lock(ctx); err != nil {
 		return nil, err
 	}
@@ -293,11 +296,11 @@ func (ms *messageSender) SendRequest(ctx context.Context, pmes *pb.Message) (*pb
 	}
 }
 
-func (ms *messageSender) writeMsg(pmes *pb.Message) error {
+func (ms *peerMessageSender) writeMsg(pmes *pb.Message) error {
 	return writeMsg(ms.s, pmes)
 }
 
-func (ms *messageSender) ctxReadMsg(ctx context.Context, mes *pb.Message) error {
+func (ms *peerMessageSender) ctxReadMsg(ctx context.Context, mes *pb.Message) error {
 	errc := make(chan error, 1)
 	go func(r msgio.ReadCloser) {
 		defer close(errc)