clientv3: only receive from closing streams in Watcher close

Was overcounting the number of expected closing messages; the resuming
list may have nil entries. Also the full client wasn't closing the watcher
client, only canceling its context, so client closes weren't joining with
the watcher shutdown.

Fixes #6605

clientv3/client.go

@@ -86,6 +86,7 @@ func NewFromConfigFile(path string) (*Client, error) {
 // Close shuts down the client's etcd connections.
 func (c *Client) Close() error {
 	c.cancel()
+	c.Watcher.Close()
 	return toErr(c.ctx, c.conn.Close())
 }
 

clientv3/watch.go

@@ -396,15 +396,17 @@ func (w *watchGrpcStream) run() {
 		for _, ws := range w.substreams {
 			if _, ok := closing[ws]; !ok {
 				close(ws.recvc)
+				closing[ws] = struct{}{}
 			}
 		}
 		for _, ws := range w.resuming {
 			if _, ok := closing[ws]; ws != nil && !ok {
 				close(ws.recvc)
+				closing[ws] = struct{}{}
 			}
 		}
 		w.joinSubstreams()
-		for toClose := len(w.substreams) + len(w.resuming); toClose > 0; toClose-- {
+		for range closing {
 			w.closeSubstream(<-w.closingc)
 		}