.

go/zodb/storage/fs1/filestorage.go

@@ -89,7 +89,7 @@ import (
 type FileStorage struct {
 	file  *os.File
 
-	// protects updates to index and to txnh{Min,Max} - in other words
+	// mu protects updates to index and to txnh{Min,Max} - in other words
 	// to everything that depends on what current last transaction is.
 	// mu also protects downErr.
 	mu      sync.RWMutex
@@ -500,13 +500,19 @@ func (fs *FileStorage) watcher(w *fsnotify.Watcher, errFirstRead chan<- error) {
 	}
 }
 
+const watchTrace = false
+
+func traceWatch(format string, argv ...interface{}) {
+	if !watchTrace {
+		return
+	}
+	log.Printf("    fs1: watcher: " + format, argv...)
+}
+
 // _watcher serves watcher and returns either when fs is closed (ok), or when
 // it hits any kind of non-recoverable error.
 func (fs *FileStorage) _watcher(w *fsnotify.Watcher, errFirstRead chan<- error) (err error) {
-	tracef := func(format string, argv ...interface{}) {
-		log.Printf("    fs1: watcher: " + format, argv...)
-	}
-	tracef(">>>")
+	traceWatch(">>>")
 
 	f := fs.file
 	idx := fs.index
@@ -529,28 +535,28 @@ func (fs *FileStorage) _watcher(w *fsnotify.Watcher, errFirstRead chan<- error)
 mainloop:
 	for {
 		if !first {
-			tracef("select ...")
+			traceWatch("select ...")
 			select {
 			case <-fs.down:
 				// closed
-				tracef("down")
+				traceWatch("down")
 				return nil
 
 			case err := <-w.Errors:
-				tracef("error")
+				traceWatch("error: %s", err)
 				if err != fsnotify.ErrEventOverflow {
 					return err
 				}
 				// events lost, but it is safe since we are always rechecking file size
 
-			case <-w.Events:
+			case ev := <-w.Events:
 				// we got some kind of "file was modified" event (e.g.
 				// write, truncate, chown ...) -> it is time to check the file again.
-				tracef("event")
+				traceWatch("event: %s", ev)
 
 			case <-tick.C:
 				// recheck the file periodically.
-				tracef("tick")
+				traceWatch("tick")
 			}
 
 			// we will be advancing through the file as much as we can.
@@ -579,7 +585,7 @@ mainloop:
 			return err
 		}
 		fsize := fi.Size()
-		tracef("toppos: %d\tfsize: %d\n", idx.TopPos, fsize)
+		traceWatch("toppos: %d\tfsize: %d\n", idx.TopPos, fsize)
 		switch {
 		case fsize == idx.TopPos:
 			continue // same as before
@@ -590,7 +596,7 @@ mainloop:
 
 		// there is some data after toppos - try to advance as much as we can.
 		// start iterating afresh with new empty buffer.
-		tracef("scanning ...")
+		traceWatch("scanning ...")
 		it := Iterate(seqReadAt(f), idx.TopPos, IterForward)
 		for {
 			err = it.NextTxn(LoadNoStrings)
@@ -629,7 +635,7 @@ mainloop:
 			// read ok - reset t₀(partial)
 			t0partial = time.Time{}
 
-			tracef("@%d tid=%s st=%q", it.Txnh.Pos, it.Txnh.Tid, it.Txnh.Status)
+			traceWatch("@%d tid=%s st=%q", it.Txnh.Pos, it.Txnh.Tid, it.Txnh.Status)
 
 			if errFirstRead != nil {
 				errFirstRead <- nil // ok
@@ -676,7 +682,7 @@ mainloop:
 			}
 			fs.mu.Unlock()
 
-			tracef("-> tid=%s  δoidv=%v", it.Txnh.Tid, oidv)
+			traceWatch("-> tid=%s  δoidv=%v", it.Txnh.Tid, oidv)
 
 			// notify client
 			if fs.watchq != nil {