From 4a908bfe2e9c9867095927527ba7ef712a8a28d1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Magiera?= <magik6k@gmail.com>
Date: Sun, 30 Jul 2017 23:25:59 +0200
Subject: [PATCH] Fix dialLimiter.fdConsuming counting

---
 .travis.yml     |  2 +-
 limiter.go      | 19 +++++++++++---
 limiter_test.go | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 448d690..96b2d5f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ os:
 language: go
 
 go:
-    - 1.7
+    - 1.8
 
 install: true
 
diff --git a/limiter.go b/limiter.go
index 67c6af4..f2513d8 100644
--- a/limiter.go
+++ b/limiter.go
@@ -52,10 +52,10 @@ func newDialLimiter(df dialfunc) *dialLimiter {
 	return newDialLimiterWithParams(df, concurrentFdDials, defaultPerPeerRateLimit)
 }
 
-func newDialLimiterWithParams(df dialfunc, fdl, ppl int) *dialLimiter {
+func newDialLimiterWithParams(df dialfunc, fdLimit, perPeerLimit int) *dialLimiter {
 	return &dialLimiter{
-		fdLimit:            fdl,
-		perPeerLimit:       ppl,
+		fdLimit:            fdLimit,
+		perPeerLimit:       perPeerLimit,
 		waitingOnPeerLimit: make(map[peer.ID][]*dialJob),
 		activePerPeer:      make(map[peer.ID]int),
 		dialFunc:           df,
@@ -68,6 +68,7 @@ func (dl *dialLimiter) finishedDial(dj *dialJob) {
 
 	if addrutil.IsFDCostlyTransport(dj.addr) {
 		dl.fdConsuming--
+
 		if len(dl.waitingOnFd) > 0 {
 			next := dl.waitingOnFd[0]
 			dl.waitingOnFd = dl.waitingOnFd[1:]
@@ -89,6 +90,7 @@ 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)
 		} else {
@@ -96,11 +98,20 @@ func (dl *dialLimiter) finishedDial(dj *dialJob) {
 		}
 		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++
+		}
+
 		// can kick this off right here, dials in this list already
 		// have the other tokens needed
 		go dl.executeDial(next)
 	}
-
 }
 
 // AddDialJob tries to take the needed tokens for starting the given dial job.
diff --git a/limiter_test.go b/limiter_test.go
index cbb6afd..3111a5d 100644
--- a/limiter_test.go
+++ b/limiter_test.go
@@ -320,3 +320,69 @@ func TestStressLimiter(t *testing.T) {
 		}
 	}
 }
+
+func TestFDLimitUnderflow(t *testing.T) {
+	dials := 0
+
+	df := func(ctx context.Context, p peer.ID, a ma.Multiaddr) (iconn.Conn, error) {
+		dials++
+
+		timeout := make(chan bool, 1)
+		go func() {
+			time.Sleep(time.Second * 5)
+			timeout <- true
+		}()
+
+		select {
+		case <-ctx.Done():
+		case <-timeout:
+		}
+
+		return nil, fmt.Errorf("df timed out")
+	}
+
+	l := newDialLimiterWithParams(df, 20, 3)
+
+	var addrs []ma.Multiaddr
+	for i := 0; i <= 1000; i++ {
+		addrs = append(addrs, addrWithPort(t, i))
+	}
+
+	for i := 0; i < 1000; i++ {
+		go func(id peer.ID, i int) {
+			ctx, cancel := context.WithCancel(context.Background())
+
+			resp := make(chan dialResult)
+			l.AddDialJob(&dialJob{
+				addr: addrs[i],
+				ctx:  ctx,
+				peer: id,
+				resp: resp,
+			})
+
+			//cancel first 60 after 1s, next 60 after 2s
+			if i > 60 {
+				time.Sleep(time.Second * 1)
+			}
+			if i < 120 {
+				time.Sleep(time.Second * 1)
+				cancel()
+				return
+			}
+			defer cancel()
+
+			for res := range resp {
+				if res.Err != nil {
+					return
+				}
+				t.Fatal("got dial res, shouldn't")
+			}
+		}(peer.ID(fmt.Sprintf("testpeer%d", i % 20)), i)
+	}
+
+	time.Sleep(time.Second * 3)
+
+	if l.fdConsuming < 0 {
+		t.Fatalf("l.fdConsuming < 0")
+	}
+}
-- 
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