Make queue operation more clear

License: MIT
Signed-off-by: Erik Ingenito <erik@carbonfive.com>

provider/provider_test.go

@@ -42,7 +42,7 @@ func TestAnnouncement(t *testing.T) {
 
 	cids := cid.NewSet()
 
-	for i := 0; i < 1000; i++ {
+	for i := 0; i < 100; i++ {
 		c := blockGenerator.Next().Cid()
 		cids.Add(c)
 	}

provider/queue.go

@@ -61,37 +61,50 @@ func (q *Queue) Dequeue() <-chan cid.Cid {
 	return q.dequeue
 }
 
+type entry struct {
+	cid cid.Cid
+	key datastore.Key
+}
+
+// Look for next Cid in the queue and return it. Skip over gaps and mangled data
+func (q *Queue) nextEntry() (datastore.Key, cid.Cid) {
+	for {
+		if q.head >= q.tail {
+			return datastore.Key{}, cid.Undef
+		}
+
+		key := q.queueKey(q.head)
+		value, err := q.ds.Get(key)
+
+		if err == datastore.ErrNotFound {
+			log.Warningf("Error missing entry in queue: %s", key)
+			q.head++ // move on
+			continue
+		} else if err != nil {
+			log.Warningf("Error fetching from queue: %s", err)
+			continue
+		}
+
+		c, err := cid.Parse(value)
+		if err != nil {
+			log.Warningf("Error marshalling Cid from queue: ", err)
+			q.head++
+			err = q.ds.Delete(key)
+			continue
+		}
+
+		return key, c
+	}
+}
+
 // Run dequeues and enqueues when available.
 func (q *Queue) work() {
 	go func() {
+
 		for {
-			var c cid.Cid = cid.Undef
-			var key datastore.Key
+			k, c := q.nextEntry()
 			var dequeue chan cid.Cid
 
-			// If we're not empty dequeue a cid and ship it
-			if q.head < q.tail {
-				key = q.queueKey(q.head)
-				value, err := q.ds.Get(key)
-
-				if err == datastore.ErrNotFound {
-					log.Warningf("Missing entry in queue: %s", err)
-					q.head++
-					continue
-				} else if err != nil {
-					log.Warningf("Error fetching from queue: %s", err)
-					continue
-				}
-
-				c, err = cid.Parse(value)
-				if err != nil {
-					log.Warningf("Error marshalling Cid from queue: ", err)
-					q.head++
-					err = q.ds.Delete(key)
-					continue
-				}
-			}
-
 			if c != cid.Undef {
 				dequeue = q.dequeue
 			}
@@ -102,16 +115,19 @@ func (q *Queue) work() {
 
 				if err := q.ds.Put(nextKey, toQueue.Bytes()); err != nil {
 					log.Errorf("Failed to enqueue cid: %s", err)
+					continue
 				}
 
 				q.tail++
 			case dequeue <- c:
-				q.head++
-				err := q.ds.Delete(key)
+				err := q.ds.Delete(k)
 
 				if err != nil {
-					log.Errorf("Failed to delete queued cid: %s", err)
+					log.Errorf("Failed to delete queued cid %s with key %s: %s", c, k, err)
+					continue
 				}
+
+				q.head++
 			case <-q.ctx.Done():
 				return
 			}