fix: handle closed queue

When the queue closes, return instead of providing empty CIDs.

simple/provider.go

@@ -85,7 +85,12 @@ func (p *Provider) handleAnnouncements() {
 				select {
 				case <-p.ctx.Done():
 					return
-				case c := <-p.queue.Dequeue():
+				case c, ok := <-p.queue.Dequeue():
+					if !ok {
+						// queue closed.
+						return
+					}
+
 					p.doProvide(c)
 				}
 			}

simple/provider_test.go

@@ -84,6 +84,37 @@ func TestAnnouncement(t *testing.T) {
 			t.Fatal("Timeout waiting for cids to be provided.")
 		}
 	}
+	prov.Close()
+
+	select {
+	case cp := <-r.provided:
+		t.Fatal("did not expect to provide CID: ", cp)
+	case <-time.After(time.Second * 1):
+	}
+}
+
+func TestClose(t *testing.T) {
+	ctx := context.Background()
+	defer ctx.Done()
+
+	ds := sync.MutexWrap(datastore.NewMapDatastore())
+	queue, err := q.NewQueue(ctx, "test", ds)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r := mockContentRouting()
+
+	prov := NewProvider(ctx, queue, r)
+	prov.Run()
+
+	prov.Close()
+
+	select {
+	case cp := <-r.provided:
+		t.Fatal("did not expect to provide anything, provided: ", cp)
+	case <-time.After(time.Second * 1):
+	}
 }
 
 func TestAnnouncementTimeout(t *testing.T) {