plugin/{file,auto}: drop fsnotify (#1090)

* plugin/{file,auto}: drop fsnotify

Reload every minute. This is more deterministic then fsnotify. Also
other thing cropped up: sharing zone files between zone; there is only
1 fsnotify event and we need to fan out the reload to all zone files.
This is a large rewrite (which could still be done), for now, poll the
zone file on disk.

Give serial no change a special error type so we can check for this.
Improve the logging for reloading:

2017/09/19 07:34:39 [INFO] Successfully reloaded zone "miek.nl." in "db.miek.nl" with serial 128263060
2017/09/19 07:34:45 [INFO] Successfully reloaded zone "miek.nl." in "db.miek.nl" with serial 128263059
2017/09/19 07:34:51 [INFO] Successfully reloaded zone "miek.nl." in "db.miek.nl" with serial 128263060

Fixes #1013

* typo

1 files changed, 29 insertions, 33 deletions

diff --git a/plugin/file/reload.go b/plugin/file/reload.go
index 18e949a94..53b57fd5e 100644
--- a/plugin/file/reload.go
+++ b/plugin/file/reload.go
@@ -3,56 +3,52 @@ package file
 import (
 	"log"
 	"os"
-	"path"
-
-	"github.com/fsnotify/fsnotify"
+	"time"
 )
 
+// TickTime is the default time we use to reload zone. Exported to be tweaked in tests.
+var TickTime = 1 * time.Minute
+
 // Reload reloads a zone when it is changed on disk. If z.NoRoload is true, no reloading will be done.
 func (z *Zone) Reload() error {
 	if z.NoReload {
 		return nil
 	}
-	watcher, err := fsnotify.NewWatcher()
-	if err != nil {
-		return err
-	}
-	err = watcher.Add(path.Dir(z.file))
-	if err != nil {
-		return err
-	}
+
+	tick := time.NewTicker(TickTime)
 
 	go func() {
-		// TODO(miek): needs to be killed on reload.
+
 		for {
 			select {
-			case event := <-watcher.Events:
-				if path.Clean(event.Name) == z.file {
 
-					reader, err := os.Open(z.file)
-					if err != nil {
-						log.Printf("[ERROR] Failed to open `%s' for `%s': %v", z.file, z.origin, err)
-						continue
-					}
+			case <-tick.C:
+				reader, err := os.Open(z.file)
+				if err != nil {
+					log.Printf("[ERROR] Failed to open zone %q in %q: %v", z.origin, z.file, err)
+					continue
+				}
 
-					serial := z.SOASerialIfDefined()
-					zone, err := Parse(reader, z.origin, z.file, serial)
-					if err != nil {
-						log.Printf("[WARNING] Parsing zone `%s': %v", z.origin, err)
-						continue
+				serial := z.SOASerialIfDefined()
+				zone, err := Parse(reader, z.origin, z.file, serial)
+				if err != nil {
+					if _, ok := err.(*serialErr); !ok {
+						log.Printf("[ERROR] Parsing zone %q: %v", z.origin, err)
 					}
+					continue
+				}
 
-					// copy elements we need
-					z.reloadMu.Lock()
-					z.Apex = zone.Apex
-					z.Tree = zone.Tree
-					z.reloadMu.Unlock()
+				// copy elements we need
+				z.reloadMu.Lock()
+				z.Apex = zone.Apex
+				z.Tree = zone.Tree
+				z.reloadMu.Unlock()
+
+				log.Printf("[INFO] Successfully reloaded zone %q in %q with serial %d", z.origin, z.file, z.Apex.SOA.Serial)
+				z.Notify()
 
-					log.Printf("[INFO] Successfully reloaded zone `%s'", z.origin)
-					z.Notify()
-				}
 			case <-z.ReloadShutdown:
-				watcher.Close()
+				tick.Stop()
 				return
 			}
 		}