From 5b449542235ce0a059a644bfa6559cbe6dc30dab Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Wed, 17 Jul 2019 11:56:25 +1000
Subject: [PATCH] Send tracker stopped event from the tracker scraper routine

Fixes potential blocking on the announce while the client lock is held, as well as differing arguments to the other announces introduced by #321.
---
 torrent.go         |  3 ---
 tracker_scraper.go | 22 +++++-----------------
 2 files changed, 5 insertions(+), 20 deletions(-)

diff --git a/torrent.go b/torrent.go
index 266d345d..33f43b30 100644
--- a/torrent.go
+++ b/torrent.go
@@ -666,9 +666,6 @@ func (t *Torrent) numPiecesCompleted() (num int) {
 }
 
 func (t *Torrent) close() (err error) {
-	for _, ta := range t.trackerAnnouncers {
-		ta.Stop()
-	}
 	t.closed.Set()
 	t.tickleReaders()
 	if t.storage != nil {
diff --git a/tracker_scraper.go b/tracker_scraper.go
index 8148c0f6..d3820179 100644
--- a/tracker_scraper.go
+++ b/tracker_scraper.go
@@ -9,16 +9,13 @@ import (
 	"time"
 
 	"github.com/anacrolix/dht/krpc"
-	"github.com/anacrolix/missinggo"
 	"github.com/anacrolix/torrent/tracker"
 )
 
 // Announces a torrent to a tracker at regular intervals, when peers are
 // required.
 type trackerScraper struct {
-	u url.URL
-	// Causes the trackerScraper to stop running.
-	stop         missinggo.Event
+	u            url.URL
 	t            *Torrent
 	lastAnnounce trackerAnnounceResult
 }
@@ -109,6 +106,7 @@ func (me *trackerScraper) announce(event tracker.AnnounceEvent) (ret trackerAnno
 	me.t.cl.lock()
 	req := me.t.announceRequest(event)
 	me.t.cl.unlock()
+	//log.Printf("announcing %s %s to %q", me.t, req.Event, me.u.String())
 	res, err := tracker.Announce{
 		HTTPProxy:  me.t.cl.config.HTTPProxy,
 		UserAgent:  me.t.cl.config.HTTPUserAgent,
@@ -131,6 +129,7 @@ func (me *trackerScraper) announce(event tracker.AnnounceEvent) (ret trackerAnno
 }
 
 func (me *trackerScraper) Run() {
+	defer me.announceStopped()
 	// make sure first announce is a "started"
 	e := tracker.Started
 	for {
@@ -159,8 +158,6 @@ func (me *trackerScraper) Run() {
 		select {
 		case <-me.t.closed.LockedChan(me.t.cl.locker()):
 			return
-		case <-me.stop.LockedChan(me.t.cl.locker()):
-			return
 		case <-wantPeers:
 			goto wait
 		case <-time.After(time.Until(ar.Completed.Add(interval))):
@@ -168,15 +165,6 @@ func (me *trackerScraper) Run() {
 	}
 }
 
-func (me *trackerScraper) Stop() {
-	req := me.t.announceRequest(tracker.Stopped)
-	ip, _ := me.getIp()
-	tracker.Announce{
-		HTTPProxy:  me.t.cl.config.HTTPProxy,
-		UserAgent:  me.t.cl.config.HTTPUserAgent,
-		TrackerUrl: me.trackerUrl(ip),
-		Request:    req,
-		HostHeader: me.u.Host,
-		ServerName: me.u.Hostname(),
-	}.Do()
+func (me *trackerScraper) announceStopped() {
+	me.announce(tracker.Stopped)
 }
-- 
2.48.1