* net/tramp.el (tramp-process-connection-type): Fix docstring.

(tramp-completion-reread-directory-timeout): Fix type.
(tramp-connection-min-time-diff): New defcustom.

* net/tramp-sh.el (tramp-maybe-open-connection): Use it.

lisp/ChangeLog

+2013-01-30  Michael Albinus  <michael.albinus@gmx.de>
+
+	* net/tramp.el (tramp-process-connection-type): Fix docstring.
+	(tramp-completion-reread-directory-timeout): Fix type.
+	(tramp-connection-min-time-diff): New defcustom.
+
+	* net/tramp-sh.el (tramp-maybe-open-connection): Use it.
+
 2013-01-30  Glenn Morris  <rgm@gnu.org>
 	* imenu.el (imenu-default-create-index-function):

lisp/net/tramp-sh.el

@@ -4357,7 +4357,7 @@ connection if a previous connection has died for some reason."
 			      (car tramp-current-connection)))
 		  (> (tramp-time-diff
 		      (current-time) (cdr tramp-current-connection))
-		     5))
+		     (or tramp-connection-min-time-diff 0)))
 	(throw 'suppress 'suppress))
 
       ;; If too much time has passed since last command was sent, look

lisp/net/tramp.el

@@ -1018,11 +1018,25 @@ this variable to be set as well."
 ;; for an override of the system default.
 (defcustom tramp-process-connection-type t
   "Overrides `process-connection-type' for connections from Tramp.
-Tramp binds process-connection-type to the value given here before
+Tramp binds `process-connection-type' to the value given here before
 opening a connection to a remote host."
   :group 'tramp
   :type '(choice (const nil) (const t) (const pty)))
 
+(defcustom tramp-connection-min-time-diff 5
+  "Defines seconds between two consecutive connection attempts.
+This is necessary as self defense mechanism, in order to avoid
+yo-yo connection attempts when the remote host is unavailable.
+
+A value of 0 or `nil' suppresses this check.  This might be
+necessary, when several out-of-order copy operations are
+performed, or when several asynchronous processes will be started
+in a short time frame.  In those cases it is recommended to
+let-bind this variable."
+  :group 'tramp
+  :version "24.4"
+  :type '(choice (const nil) integer))
+
 (defcustom tramp-completion-reread-directory-timeout 10
   "Defines seconds since last remote command before rereading a directory.
 A remote directory might have changed its contents.  In order to
@@ -1033,7 +1047,7 @@ have been gone since last remote command execution.  A value of `t'
 would require an immediate reread during filename completion, `nil'
 means to use always cached values for the directory contents."
   :group 'tramp
-  :type '(choice (const nil) integer))
+  :type '(choice (const nil) (const t) integer))
 
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