feat: improve protocol interning

This used to specify a max size/count but that was only because this logic was
shared between all peerstores (including the on-disk one). Now that:

1. This only applies to the in-memory one.
2. We never actually GC these.

We can just intern indefinitely.

pstoremem/protobook.go

@@ -8,11 +8,6 @@ import (
 	pstore "github.com/libp2p/go-libp2p-peerstore"
 )
 
-const (
-	maxInternedProtocols    = 512
-	maxInternedProtocolSize = 256
-)
-
 type protoSegment struct {
 	sync.RWMutex
 	protocols map[peer.ID]map[string]struct{}
@@ -35,7 +30,7 @@ var _ pstore.ProtoBook = (*memoryProtoBook)(nil)
 
 func NewProtoBook() pstore.ProtoBook {
 	return &memoryProtoBook{
-		interned: make(map[string]string, maxInternedProtocols),
+		interned: make(map[string]string, 256),
 		segments: func() (ret protoSegments) {
 			for i := range ret {
 				ret[i] = &protoSegment{
@@ -48,10 +43,6 @@ func NewProtoBook() pstore.ProtoBook {
 }
 
 func (pb *memoryProtoBook) internProtocol(proto string) string {
-	if len(proto) > maxInternedProtocolSize {
-		return proto
-	}
-
 	// check if it is interned with the read lock
 	pb.lk.RLock()
 	interned, ok := pb.interned[proto]
@@ -71,11 +62,6 @@ func (pb *memoryProtoBook) internProtocol(proto string) string {
 		return interned
 	}
 
-	// if we've filled the table, throw it away and start over
-	if len(pb.interned) >= maxInternedProtocols {
-		pb.interned = make(map[string]string, maxInternedProtocols)
-	}
-
 	pb.interned[proto] = proto
 	return proto
 }