.

wcfs/wcfs.go

@@ -495,6 +495,7 @@ type Watcher struct {
 	// established file watchers.
 	// XXX in-progress - where?	-> nowhere; here only established watches are added
 	// XXX locking?
+	// XXX -> {} foid -> FileWatch
 	fileTab map[*FileWatch]struct{}
 
 	// IO
@@ -1239,9 +1240,8 @@ retry:
 //
 // XXX describe more.
 // XXX explain that if rev ≤ .at there is no rev_next: rev < rev_next ≤ at.
-// XXX error - when?
+// XXX error - when? or close watch on any error?
 //
-// XXX -> WatchFile.Pin(blk, at)
 // XXX place=ok?
 func (w *FileWatch) pin(ctx context.Context, blk int64, rev zodb.Tid) (err error) {
 	foid := w.file.zfile.POid()
@@ -1275,6 +1275,35 @@ func (w *FileWatch) pin(ctx context.Context, blk int64, rev zodb.Tid) (err error
 	return nil
 }
 
+// setupWatch sets up new FileWatch when client sends `watch <file> @<at>`.
+//
+// XXX place=ok?
+func (watch *Watcher) setupWatch(ctx context.Context, foid zodb.Oid, at zodb.Tid) (err error) {
+	defer xerr.Contextf(&err, "setup watch f<%s> @%s", foid, at)
+	// XXX locking
+
+	// XXX at = zobd.InvalidTid - remove watch
+
+	// XXX if watch was already established - we need to update it
+	w = watch.fileTab[foid]
+	if w != nil {
+		// XXX update the watch
+	}
+
+	// watch was not previously established - set it up anew
+	// XXX locking
+	f := watch.head.bfdir.fileTab[foid]
+	if f == nil {
+		// by "invalidation protocol" watch is setup after data file was opened
+		return fmt.Errorf("file not yet known or is not a ZBigFile")
+	}
+
+	// XXX wait watch.head.zconn.At() ≥ at
+
+
+
+}
+
 
 // ---- Watch server ----
 
@@ -1344,18 +1373,15 @@ func (w *Watcher) _serveRX() (err error) {
 			continue
 		}
 
-		// client-initiated request
-		oid, at, err := parseWatch(msg)
+		// client-initiated watch request
+		foid, at, err := parseWatch(msg)
 		if err != nil {
 			return fmt.Errorf("%d: %s", stream, err)
 		}
 
-		_ = oid
-		_ = at
-
-		_, err = fmt.Fprintf(w.sk, "%d error TODO\n", stream)
+		err = w.setupWatch(foid, at)
 		if err != nil {
-			return err
+			return fmt.Errorf("%d: %s", stream, err)
 		}
 	}
 }