fix: fix reload causing secondary plugin goroutine to leak. (#7694)

Signed-off-by: wenxuan70 <t736660416@gmail.com>

plugin/file/secondary.go

@@ -107,7 +107,7 @@ func less(a, b uint32) bool {
 // and uses the SOA parameters. Every refresh it will check for a new SOA number. If that fails (for all
 // server) it will retry every retry interval. If the zone failed to transfer before the expire, the zone
 // will be marked expired.
-func (z *Zone) Update() error {
+func (z *Zone) Update(updateShutdown chan bool) error {
 	// If we don't have a SOA, we don't have a zone, wait for it to appear.
 	for z.SOA == nil {
 		time.Sleep(1 * time.Second)
@@ -183,6 +183,12 @@ Restart:
 			retryTicker.Stop()
 			expireTicker.Stop()
 			goto Restart
+
+		case <-updateShutdown:
+			refreshTicker.Stop()
+			retryTicker.Stop()
+			expireTicker.Stop()
+			return nil
 		}
 	}
 }

plugin/secondary/setup.go

@@ -27,6 +27,9 @@ func setup(c *caddy.Controller) error {
 		n := zones.Names[i]
 		z := zones.Z[n]
 		if len(z.TransferFrom) > 0 {
+			// In order to support secondary plugin reloading.
+			updateShutdown := make(chan bool)
+
 			c.OnStartup(func() error {
 				z.StartupOnce.Do(func() {
 					go func() {
@@ -43,12 +46,21 @@ func setup(c *caddy.Controller) error {
 							if dur > max {
 								dur = max
 							}
+							select {
+							case <-updateShutdown:
+								return
+							default:
 							}
-						z.Update()
+						}
+						z.Update(updateShutdown)
 					}()
 				})
 				return nil
 			})
+			c.OnShutdown(func() error {
+				updateShutdown <- true
+				return nil
+			})
 		}
 	}