refactor: replace custom paych pubsub with existing impl

go.mod

@@ -44,6 +44,7 @@ require (
 	github.com/google/uuid v1.1.1
 	github.com/gorilla/mux v1.7.4
 	github.com/gorilla/websocket v1.4.2
+	github.com/hannahhoward/go-pubsub v0.0.0-20200423002714-8d62886cc36e
 	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/influxdata/influxdb1-client v0.0.0-20191209144304-8bf82d3c094d

paychmgr/msglistener.go

@@ -1,61 +1,56 @@
 package paychmgr
 
 import (
-	"sync"
+	"golang.org/x/xerrors"
+
+	"github.com/hannahhoward/go-pubsub"
 
-	"github.com/google/uuid"
 	"github.com/ipfs/go-cid"
 )
 
-type msgListener struct {
-	id string
-	cb func(c cid.Cid, err error)
-}
-
 type msgListeners struct {
-	lk        sync.Mutex
-	listeners []*msgListener
+	ps *pubsub.PubSub
 }
 
-func (ml *msgListeners) onMsg(mcid cid.Cid, cb func(error)) string {
-	ml.lk.Lock()
-	defer ml.lk.Unlock()
-
-	l := &msgListener{
-		id: uuid.New().String(),
-		cb: func(c cid.Cid, err error) {
-			if mcid.Equals(c) {
-				cb(err)
-			}
-		},
-	}
-	ml.listeners = append(ml.listeners, l)
-	return l.id
+type msgCompleteEvt struct {
+	mcid cid.Cid
+	err  error
 }
 
-func (ml *msgListeners) fireMsgComplete(mcid cid.Cid, err error) {
-	ml.lk.Lock()
-	defer ml.lk.Unlock()
+type subscriberFn func(msgCompleteEvt)
 
-	for _, l := range ml.listeners {
-		l.cb(mcid, err)
-	}
+func newMsgListeners() msgListeners {
+	ps := pubsub.New(func(event pubsub.Event, subFn pubsub.SubscriberFn) error {
+		evt, ok := event.(msgCompleteEvt)
+		if !ok {
+			return xerrors.Errorf("wrong type of event")
+		}
+		sub, ok := subFn.(subscriberFn)
+		if !ok {
+			return xerrors.Errorf("wrong type of subscriber")
+		}
+		sub(evt)
+		return nil
+	})
+	return msgListeners{ps: ps}
 }
 
-func (ml *msgListeners) unsubscribe(sub string) {
-	ml.lk.Lock()
-	defer ml.lk.Unlock()
-
-	for i, l := range ml.listeners {
-		if l.id == sub {
-			ml.removeListener(i)
-			return
+// onMsgComplete registers a callback for when the message with the given cid
+// completes
+func (ml *msgListeners) onMsgComplete(mcid cid.Cid, cb func(error)) pubsub.Unsubscribe {
+	var fn subscriberFn = func(evt msgCompleteEvt) {
+		if mcid.Equals(evt.mcid) {
+			cb(evt.err)
 		}
 	}
+	return ml.ps.Subscribe(fn)
 }
 
-func (ml *msgListeners) removeListener(i int) {
-	copy(ml.listeners[i:], ml.listeners[i+1:])
-	ml.listeners[len(ml.listeners)-1] = nil
-	ml.listeners = ml.listeners[:len(ml.listeners)-1]
+// fireMsgComplete is called when a message completes
+func (ml *msgListeners) fireMsgComplete(mcid cid.Cid, err error) {
+	e := ml.ps.Publish(msgCompleteEvt{mcid: mcid, err: err})
+	if e != nil {
+		// In theory we shouldn't ever get an error here
+		log.Errorf("unexpected error publishing message complete: %s", e)
+	}
 }

paychmgr/msglistener_test.go

@@ -17,12 +17,12 @@ func testCids() []cid.Cid {
 }
 
 func TestMsgListener(t *testing.T) {
-	var ml msgListeners
+	ml := newMsgListeners()
 
 	done := false
 	experr := xerrors.Errorf("some err")
 	cids := testCids()
-	ml.onMsg(cids[0], func(err error) {
+	ml.onMsgComplete(cids[0], func(err error) {
 		require.Equal(t, experr, err)
 		done = true
 	})
@@ -35,11 +35,11 @@ func TestMsgListener(t *testing.T) {
 }
 
 func TestMsgListenerNilErr(t *testing.T) {
-	var ml msgListeners
+	ml := newMsgListeners()
 
 	done := false
 	cids := testCids()
-	ml.onMsg(cids[0], func(err error) {
+	ml.onMsgComplete(cids[0], func(err error) {
 		require.Nil(t, err)
 		done = true
 	})
@@ -52,20 +52,20 @@ func TestMsgListenerNilErr(t *testing.T) {
 }
 
 func TestMsgListenerUnsub(t *testing.T) {
-	var ml msgListeners
+	ml := newMsgListeners()
 
 	done := false
 	experr := xerrors.Errorf("some err")
 	cids := testCids()
-	id1 := ml.onMsg(cids[0], func(err error) {
+	unsub := ml.onMsgComplete(cids[0], func(err error) {
 		t.Fatal("should not call unsubscribed listener")
 	})
-	ml.onMsg(cids[0], func(err error) {
+	ml.onMsgComplete(cids[0], func(err error) {
 		require.Equal(t, experr, err)
 		done = true
 	})
 
-	ml.unsubscribe(id1)
+	unsub()
 	ml.fireMsgComplete(cids[0], experr)
 
 	if !done {
@@ -74,17 +74,17 @@ func TestMsgListenerUnsub(t *testing.T) {
 }
 
 func TestMsgListenerMulti(t *testing.T) {
-	var ml msgListeners
+	ml := newMsgListeners()
 
 	count := 0
 	cids := testCids()
-	ml.onMsg(cids[0], func(err error) {
+	ml.onMsgComplete(cids[0], func(err error) {
 		count++
 	})
-	ml.onMsg(cids[0], func(err error) {
+	ml.onMsgComplete(cids[0], func(err error) {
 		count++
 	})
-	ml.onMsg(cids[1], func(err error) {
+	ml.onMsgComplete(cids[1], func(err error) {
 		count++
 	})
 

paychmgr/paych.go

@@ -35,12 +35,13 @@ type channelAccessor struct {
 
 func newChannelAccessor(pm *Manager) *channelAccessor {
 	return &channelAccessor{
-		lk:      &channelLock{globalLock: &pm.lk},
-		sm:      pm.sm,
-		sa:      &stateAccessor{sm: pm.sm},
-		api:     pm.pchapi,
-		store:   pm.store,
-		waitCtx: pm.ctx,
+		lk:           &channelLock{globalLock: &pm.lk},
+		sm:           pm.sm,
+		sa:           &stateAccessor{sm: pm.sm},
+		api:          pm.pchapi,
+		store:        pm.store,
+		msgListeners: newMsgListeners(),
+		waitCtx:      pm.ctx,
 	}
 }
 

paychmgr/simple.go

@@ -640,7 +640,7 @@ type onMsgRes struct {
 func (ca *channelAccessor) msgPromise(ctx context.Context, mcid cid.Cid) chan onMsgRes {
 	promise := make(chan onMsgRes)
 	triggerUnsub := make(chan struct{})
-	sub := ca.msgListeners.onMsg(mcid, func(err error) {
+	unsub := ca.msgListeners.onMsgComplete(mcid, func(err error) {
 		close(triggerUnsub)
 
 		// Use a go-routine so as not to block the event handler loop
@@ -671,7 +671,7 @@ func (ca *channelAccessor) msgPromise(ctx context.Context, mcid cid.Cid) chan on
 		case <-triggerUnsub:
 		}
 
-		ca.msgListeners.unsubscribe(sub)
+		unsub()
 	}()
 
 	return promise