don't spam searches for unused connections. todo: timeout old connections somehow

src/yggdrasil/conn.go

@@ -37,6 +37,7 @@ type Conn struct {
 	writeDeadline atomic.Value  // time.Time // TODO timer
 	searching     atomic.Value  // bool
 	searchwait    chan struct{} // Never reset this, it's only used for the initial search
+	writebuf      [][]byte      // Packets to be sent if/when the search finishes
 }
 
 // TODO func NewConn() that initializes additional fields as needed
@@ -60,23 +61,13 @@ func (c *Conn) String() string {
 func (c *Conn) startSearch() {
 	// The searchCompleted callback is given to the search
 	searchCompleted := func(sinfo *sessionInfo, err error) {
+		defer c.searching.Store(false)
 		// If the search failed for some reason, e.g. it hit a dead end or timed
 		// out, then do nothing
 		if err != nil {
 			c.core.log.Debugln(c.String(), "DHT search failed:", err)
-			go func() {
-				time.Sleep(time.Second)
-				c.mutex.RLock()
-				closed := c.closed
-				c.mutex.RUnlock()
-				if !closed {
-					// Restart the search, or else Write can stay blocked forever
-					c.core.router.admin <- c.startSearch
-				}
-			}()
 			return
 		}
-		defer c.searching.Store(false)
 		// Take the connection mutex
 		c.mutex.Lock()
 		defer c.mutex.Unlock()
@@ -102,6 +93,16 @@ func (c *Conn) startSearch() {
 			// Things were closed before the search returned
 			// Go ahead and close it again to make sure the session is cleaned up
 			go c.Close()
+		} else {
+			// Send any messages we may have buffered
+			var msgs [][]byte
+			msgs, c.writebuf = c.writebuf, nil
+			go func() {
+				for _, msg := range msgs {
+					c.Write(msg)
+					util.PutBytes(msg)
+				}
+			}()
 		}
 	}
 	// doSearch will be called below in response to one or more conditions
@@ -238,8 +239,6 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 	c.mutex.RLock()
 	sinfo := c.session
 	c.mutex.RUnlock()
-	timer := getDeadlineTimer(&c.writeDeadline)
-	defer util.TimerStop(timer)
 	// If the session doesn't exist, or isn't initialised (which probably means
 	// that the search didn't complete successfully) then we may need to wait for
 	// the search to complete or start the search again
@@ -249,22 +248,15 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 			// No search was already taking place so start a new one
 			c.core.router.doAdmin(c.startSearch)
 		}
-		// Wait for the search to complete
-		select {
-		case <-c.searchwait:
-		case <-timer.C:
-			return 0, ConnError{errors.New("Timeout"), true, false}
-		}
-		// Retrieve our session info again
-		c.mutex.RLock()
-		sinfo = c.session
-		c.mutex.RUnlock()
-		// If sinfo is still nil at this point then the search failed and the
-		// searchwait channel has been recreated, so might as well give up and
-		// return an error code
-		if sinfo == nil {
-			return 0, errors.New("search failed")
+		// Buffer the packet to be sent if/when the search is finished
+		c.mutex.Lock()
+		defer c.mutex.Unlock()
+		c.writebuf = append(c.writebuf, append(util.GetBytes(), b...))
+		for len(c.writebuf) > 32 {
+			util.PutBytes(c.writebuf[0])
+			c.writebuf = c.writebuf[1:]
 		}
+		return len(b), nil
 	}
 	var packet []byte
 	done := make(chan struct{})
@@ -283,13 +275,17 @@ func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
 		packet = p.encode()
 		sinfo.bytesSent += uint64(len(b))
 	}
+	// Set up a timer so this doesn't block forever
+	timer := getDeadlineTimer(&c.writeDeadline)
+	defer util.TimerStop(timer)
 	// Hand over to the session worker
 	select { // Send to worker
 	case sinfo.worker <- workerFunc:
 	case <-timer.C:
 		return 0, ConnError{errors.New("Timeout"), true, false}
 	}
-	<-done // Wait for the worker to finish, failing this can cause memory errors (util.[Get||Put]Bytes stuff)
+	// Wait for the worker to finish, otherwise there are memory errors ([Get||Put]Bytes stuff)
+	<-done
 	// Give the packet to the router
 	sinfo.core.router.out(packet)
 	// Finally return the number of bytes we wrote