limiter: cleanup the code

p2p/net/swarm/limiter.go

@@ -34,12 +34,13 @@ func (dj *dialJob) cancelled() bool {
 }
 
 type dialLimiter struct {
-	rllock      sync.Mutex
+	lk sync.Mutex
+
 	fdConsuming int
 	fdLimit     int
 	waitingOnFd []*dialJob
 
-	dialFunc func(context.Context, peer.ID, ma.Multiaddr) (transport.Conn, error)
+	dialFunc dialfunc
 
 	activePerPeer      map[peer.ID]int
 	perPeerLimit       int
@@ -62,26 +63,26 @@ func newDialLimiterWithParams(df dialfunc, fdLimit, perPeerLimit int) *dialLimit
 	}
 }
 
-func (dl *dialLimiter) finishedDial(dj *dialJob) {
-	dl.rllock.Lock()
-	defer dl.rllock.Unlock()
-
-	if addrutil.IsFDCostlyTransport(dj.addr) {
-		dl.fdConsuming--
-
-		if len(dl.waitingOnFd) > 0 {
-			next := dl.waitingOnFd[0]
-			dl.waitingOnFd[0] = nil // clear out memory
-			dl.waitingOnFd = dl.waitingOnFd[1:]
-			if len(dl.waitingOnFd) == 0 {
-				dl.waitingOnFd = nil // clear out memory
-			}
-			dl.fdConsuming++
-
-			go dl.executeDial(next)
+// freeFDToken frees FD token and if there are any schedules another waiting dialJob
+// in it's place
+func (dl *dialLimiter) freeFDToken() {
+	dl.fdConsuming--
+
+	if len(dl.waitingOnFd) > 0 {
+		next := dl.waitingOnFd[0]
+		dl.waitingOnFd[0] = nil // clear out memory
+		dl.waitingOnFd = dl.waitingOnFd[1:]
+		if len(dl.waitingOnFd) == 0 {
+			dl.waitingOnFd = nil // clear out memory
 		}
+		dl.fdConsuming++
+
+		// we already have activePerPeer token at this point so we can just dial
+		go dl.executeDial(next)
 	}
+}
 
+func (dl *dialLimiter) freePeerToken(dj *dialJob) {
 	// release tokens in reverse order than we take them
 	dl.activePerPeer[dj.peer]--
 	if dl.activePerPeer[dj.peer] == 0 {
@@ -91,45 +92,31 @@ func (dl *dialLimiter) finishedDial(dj *dialJob) {
 	waitlist := dl.waitingOnPeerLimit[dj.peer]
 	if !dj.success && len(waitlist) > 0 {
 		next := waitlist[0]
-
 		if len(waitlist) == 1 {
-			delete(dl.waitingOnPeerLimit, dj.peer)
+			delete(dl.waitingOnPeerLimit, next.peer)
 		} else {
 			waitlist[0] = nil // clear out memory
-			dl.waitingOnPeerLimit[dj.peer] = waitlist[1:]
+			dl.waitingOnPeerLimit[next.peer] = waitlist[1:]
 		}
-		dl.activePerPeer[dj.peer]++ // just kidding, we still want this token
 
-		if addrutil.IsFDCostlyTransport(next.addr) {
-			if dl.fdConsuming >= dl.fdLimit {
-				dl.waitingOnFd = append(dl.waitingOnFd, next)
-				return
-			}
-
-			// take token
-			dl.fdConsuming++
-		}
+		dl.activePerPeer[next.peer]++ // just kidding, we still want this token
 
-		// can kick this off right here, dials in this list already
-		// have the other tokens needed
-		go dl.executeDial(next)
+		dl.addCheckFdLimit(next)
 	}
 }
 
-// AddDialJob tries to take the needed tokens for starting the given dial job.
-// If it acquires all needed tokens, it immediately starts the dial, otherwise
-// it will put it on the waitlist for the requested token.
-func (dl *dialLimiter) AddDialJob(dj *dialJob) {
-	dl.rllock.Lock()
-	defer dl.rllock.Unlock()
+func (dl *dialLimiter) finishedDial(dj *dialJob) {
+	dl.lk.Lock()
+	defer dl.lk.Unlock()
 
-	if dl.activePerPeer[dj.peer] >= dl.perPeerLimit {
-		wlist := dl.waitingOnPeerLimit[dj.peer]
-		dl.waitingOnPeerLimit[dj.peer] = append(wlist, dj)
-		return
+	if addrutil.IsFDCostlyTransport(dj.addr) {
+		dl.freeFDToken()
 	}
-	dl.activePerPeer[dj.peer]++
 
+	dl.freePeerToken(dj)
+}
+
+func (dl *dialLimiter) addCheckFdLimit(dj *dialJob) {
 	if addrutil.IsFDCostlyTransport(dj.addr) {
 		if dl.fdConsuming >= dl.fdLimit {
 			dl.waitingOnFd = append(dl.waitingOnFd, dj)
@@ -140,15 +127,35 @@ func (dl *dialLimiter) AddDialJob(dj *dialJob) {
 		dl.fdConsuming++
 	}
 
-	// take second needed token and start dial!
 	go dl.executeDial(dj)
 }
 
+func (dl *dialLimiter) addCheckPeerLimit(dj *dialJob) {
+	if dl.activePerPeer[dj.peer] >= dl.perPeerLimit {
+		wlist := dl.waitingOnPeerLimit[dj.peer]
+		dl.waitingOnPeerLimit[dj.peer] = append(wlist, dj)
+		return
+	}
+	dl.activePerPeer[dj.peer]++
+
+	dl.addCheckFdLimit(dj)
+}
+
+// AddDialJob tries to take the needed tokens for starting the given dial job.
+// If it acquires all needed tokens, it immediately starts the dial, otherwise
+// it will put it on the waitlist for the requested token.
+func (dl *dialLimiter) AddDialJob(dj *dialJob) {
+	dl.lk.Lock()
+	defer dl.lk.Unlock()
+
+	dl.addCheckPeerLimit(dj)
+}
+
 func (dl *dialLimiter) clearAllPeerDials(p peer.ID) {
-	dl.rllock.Lock()
-	defer dl.rllock.Unlock()
+	dl.lk.Lock()
+	defer dl.lk.Unlock()
 	delete(dl.waitingOnPeerLimit, p)
-	// NB: the waitingOnFd list doesnt need to be cleaned out here, we will
+	// NB: the waitingOnFd list doesn't need to be cleaned out here, we will
 	// remove them as we encounter them because they are 'cancelled' at this
 	// point
 }

p2p/net/swarm/limiter_test.go

@@ -378,9 +378,9 @@ func TestFDLimitUnderflow(t *testing.T) {
 
 	time.Sleep(time.Second * 3)
 
-	l.rllock.Lock()
+	l.lk.Lock()
 	fdConsuming := l.fdConsuming
-	l.rllock.Unlock()
+	l.lk.Unlock()
 
 	if fdConsuming < 0 {
 		t.Fatalf("l.fdConsuming < 0")