add more comments, clean up module

get.go

@@ -6,19 +6,22 @@ import (
 	"sync/atomic"
 )
 
-func handleGet(pathID string, w http.ResponseWriter, r *http.Request) {
-	queue := &Queue{ch: make(chan Transfer)}
-	if p, loaded := paths.LoadOrStore(pathID, queue); loaded {
-		queue = p.(*Queue)
-		debug("%s [GET] Loads path", pathID)
-	} else {
-		debug("%s [GET] Created path", pathID)
+// handleGet simply attempts to relay whatever data is received from the first
+// available POST request into this GET request on the same path.
+// if there is no POST waiting, it will block indefinitely until it either finds
+// a POST or the connection is cancelled.
+func (pw *Pathway) handleGet(pathID string, w http.ResponseWriter, r *http.Request) {
+	// GET creates a new path preemptively
+	queue := &transferQueue{ch: make(chan httpTransfer)}
+	if p, loaded := pw.LoadOrStore(pathID, queue); loaded {
+		// GET successfully loads a path instead
+		queue = p.(*transferQueue)
 	}
 	atomic.AddInt32(&queue.gets, 1)
 
 	select {
+	// either a POST presents itself on the other side of the queue's channel
 	case transfer := <-queue.ch:
-		debug("%s [GET] Reads from path", pathID)
 		if transfer.contentlength != "" {
 			w.Header().Set("Content-Length", transfer.contentlength)
 		}
@@ -26,17 +29,17 @@ func handleGet(pathID string, w http.ResponseWriter, r *http.Request) {
 		if err != nil {
 			transfer.reader.Close()
 		}
-		debug("%s [GET] Sends done", pathID)
 		close(transfer.done)
+	// or the request is cancelled, and this GET can continue to finish
 	case <-r.Context().Done():
-		debug("%s [GET] Cancels path", pathID)
 	}
 
+	// if this was indeed the last GET and there are no more new POST requests
+	// waiting, then go ahead and close the queue and remove the path
 	if atomic.AddInt32(&queue.gets, -1) <= 0 {
 		if atomic.LoadInt32(&queue.posts) <= 0 {
-			paths.Delete(pathID)
-			debug("%s [GET] Removes path", pathID)
+			pw.Delete(pathID)
+			close(queue.ch)
 		}
 	}
-	info("%s [GET] Finishes", pathID)
 }