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Fix close of closed channel #427

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merged 2 commits into from
Jun 15, 2021
Merged

Fix close of closed channel #427

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ffa5c81
Fix close of closed channel
gammazero Jun 14, 2021
52a7006
Make close concurrent safe
gammazero Jun 14, 2021
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2 changes: 2 additions & 0 deletions go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46f
github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23/go.mod h1:bbYlZJ7hK1yFx9hf58LP0zeX7UjIGs20ufpu3evjr+s=
github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
github.com/cheekybits/genny v1.0.0 h1:uGGa4nei+j20rOSeDeP5Of12XVm7TGUd4dJA9RDitfE=
github.com/cheekybits/genny v1.0.0/go.mod h1:+tQajlRqAUrPI7DOSpB0XAqZYtQakVtB7wXkRAgjxjQ=
github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
Expand Down Expand Up @@ -600,6 +601,7 @@ gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMy
gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
gopkg.in/src-d/go-cli.v0 v0.0.0-20181105080154-d492247bbc0d/go.mod h1:z+K8VcOYVYcSwSjGebuDL6176A1XskgbtNl64NSg+n8=
gopkg.in/src-d/go-log.v1 v1.0.1/go.mod h1:GN34hKP0g305ysm2/hctJ0Y8nWP3zxXXJ8GFabTyABE=
gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
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6 changes: 5 additions & 1 deletion subscription.go
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Expand Up @@ -10,6 +10,7 @@ type Subscription struct {
topic string
ch chan *Message
cancelCh chan<- *Subscription
closed bool
ctx context.Context
err error
}
Expand Down Expand Up @@ -43,5 +44,8 @@ func (sub *Subscription) Cancel() {
}

func (sub *Subscription) close() {
close(sub.ch)
if !sub.closed {
close(sub.ch)
sub.closed = true
}
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this needs to be atomic or we can have two concurrent closes fail; can you make this an swap/compare with an atomic variable?

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Looked like close is never called concurrently; only called by the handler goroutine. ...but in case it is someday...

}
34 changes: 34 additions & 0 deletions topic_test.go
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Expand Up @@ -679,6 +679,40 @@ func TestTopicRelayOnClosedTopic(t *testing.T) {
}
}

func TestProducePanic(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()

const numHosts = 5
topicID := "foobar"
hosts := getNetHosts(t, ctx, numHosts)
ps := getPubsub(ctx, hosts[0])

// Create topic
topic, err := ps.Join(topicID)
if err != nil {
t.Fatal(err)
}

// Create subscription we're going to cancel
s, err := topic.Subscribe()
if err != nil {
t.Fatal(err)
}
// Create second subscription to keep us alive on the subscription map
// after the first one is canceled
s2, err := topic.Subscribe()
if err != nil {
t.Fatal(err)
}
_ = s2

s.Cancel()
time.Sleep(time.Second)
s.Cancel()
time.Sleep(time.Second)
}

func notifSubThenUnSub(ctx context.Context, t *testing.T, topics []*Topic) {
primaryTopic := topics[0]
msgs := make([]*Subscription, len(topics))
Expand Down