Optimize host name completion in Tramp

* lisp/net/tramp-adb.el (tramp-adb-maybe-open-connection):
* lisp/net/tramp-gvfs.el (tramp-gvfs-maybe-open-connection):
* lisp/net/tramp-rclone.el (tramp-rclone-maybe-open-connection):
* lisp/net/tramp-sh.el (tramp-maybe-open-connection):
* lisp/net/tramp-smb.el (tramp-smb-maybe-open-connection):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-maybe-open-connection):
Throw `non-essential' at the beginning of the function.

* lisp/net/tramp.el (tramp-handle-file-exists-p):
* lisp/net/tramp-sh.el (tramp-sh-handle-file-exists-p):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-file-exists-p):
Run only when host is connectable.  This is due to host name
completion, which shall be optimized.

* lisp/net/tramp-smb.el (tramp-smb-do-file-attributes-with-stat)
(tramp-smb-get-file-entries): Access connection buffer only after
sending the command.

* lisp/net/tramp.el (tramp-get-buffer, tramp-get-connection-buffer):
New argument DONT-CREATE.
(tramp-message): Use it.
(tramp-get-mutex): Check, whether host is connectable.
(tramp-file-name-handler): Set thread only when host is connectable.
(tramp-connectable-p): Allow also VEC as argument.
(tramp-completion-handle-file-name-completion): Do not expand directory.

1 files changed, 4 insertions, 9 deletions

diff --git a/lisp/net/tramp-rclone.el b/lisp/net/tramp-rclone.el
index 866e7791bf8..1f0c7eadbc5 100644
--- a/lisp/net/tramp-rclone.el
+++ b/lisp/net/tramp-rclone.el
@@ -520,19 +520,14 @@ file names."
   "Maybe open a connection VEC.
 Does not do anything if a connection is already open, but re-opens the
 connection if a previous connection has died for some reason."
+  ;; During completion, don't reopen a new connection.
+  (unless (tramp-connectable-p vec)
+    (throw 'non-essential 'non-essential))
+
   (let ((host (tramp-file-name-host vec)))
     (when (rassoc `(,host) (tramp-rclone-parse-device-names nil))
       (if (zerop (length host))
 	  (tramp-error vec 'file-error "Storage %s not connected" host))
-
-      ;; During completion, don't reopen a new connection.  We check
-      ;; this for the process related to `tramp-buffer-name';
-      ;; otherwise `start-file-process' wouldn't run ever when
-      ;; `non-essential' is non-nil.
-      (when (and (tramp-completion-mode-p)
-		 (null (get-process (tramp-buffer-name vec))))
-	(throw 'non-essential 'non-essential))
-
       ;; We need a process bound to the connection buffer.  Therefore,
       ;; we create a dummy process.  Maybe there is a better solution?
       (unless (get-buffer-process (tramp-get-connection-buffer vec))