.

wcfs/wcfs.go

@@ -692,17 +692,11 @@ func traceZWatch(format string, argv ...interface{}) {
 // zwatcher watches for ZODB changes.
 //
 // see "4) when we receive an invalidation message from ZODB ..."
-func (root *Root) zwatcher(ctx context.Context) (err error) {
-	defer xerr.Contextf(&err, "zwatch")	// XXX more in context?
-	// XXX unmount on error? -> always EIO?
-
+func (root *Root) zwatcher(ctx context.Context, zwatchq chan zodb.Event) (err error) {
+	defer xerr.Contextf(&err, "zwatch %s", root.zstor.URL())
+	// XXX error -> always EIO for data operations
 	traceZWatch(">>>")
 
-	zwatchq := make(chan zodb.Event)
-	at0 := root.zstor.AddWatch(zwatchq)	// XXX -> to main thread to avoid race
-	defer root.zstor.DelWatch(zwatchq)
-	_ = at0 // XXX XXX
-
 	var zevent zodb.Event
 	var ok bool
 
@@ -2176,7 +2170,7 @@ func main() {
 		stdlog.SetFlags(stdlog.Lmicroseconds)
 	}
 
-	// open zodb storage/db/connection
+	// open zodb storage/watch/db/connection
 	ctx := context.Background()	// XXX + timeout?
 	zstor, err := zodb.Open(ctx, zurl, &zodb.OpenOptions{
 		ReadOnly: true,
@@ -2186,9 +2180,15 @@ func main() {
 	}
 	defer zstor.Close()
 
+	zwatchq := make(chan zodb.Event)
+	at0 := zstor.AddWatch(zwatchq)
+	defer zstor.DelWatch(zwatchq)
+
 	zdb := zodb.NewDB(zstor)
 	defer zdb.Close()	// XXX err
 	zhead, err := zopen(ctx, zdb, &zodb.ConnOptions{
+		At: at0,
+
 		// we need zhead.cache to be maintained across several transactions.
 		// see "3) for head/bigfile/* the following invariant is maintained ..."
 		NoPool: true,
@@ -2299,8 +2299,8 @@ func main() {
 
 	// XXX place = ok?
 	// XXX ctx = ok?
-	// XXX wait for zwatcher shutdown.
-	go root.zwatcher(ctx)
+	// XXX wait for zwatcher shutdown + log from it error
+	go root.zwatcher(ctx, zwatchq)
 
 	// TODO handle autoexit
 	// (exit when kernel forgets all our inodes - wcfs.py keeps .wcfs/zurl