* net/tramp-cache.el (top): Autoload `tramp-time-less-p'.

(tramp-cache-inhibit-cache): Extend doc string.  It allows also
timestamps.
(tramp-get-file-property): Check for timestamps in
`tramp-cache-inhibit-cache'.
(tramp-set-file-property): Write timestamp.

diff --git a/lisp/net/tramp-cache.el b/lisp/net/tramp-cache.el
index 49bbd79cb4522ea24599680fe1bc6ea8a16c8764..3b1f4d46aaddb4eca64fb301c0941a1ed5331fda 100644 (file)
--- a/lisp/net/tramp-cache.el
+++ b/lisp/net/tramp-cache.el
@@ -62,6 +62,7 @@
   (autoload 'tramp-file-name-host "tramp")
   (autoload 'tramp-file-name-localname "tramp")
   (autoload 'tramp-run-real-handler "tramp")
+  (autoload 'tramp-time-less-p "tramp")
   (autoload 'time-stamp-string "time-stamp"))
 
 ;;; -- Cache --
@@ -70,7 +71,11 @@
   "Hash table for remote files properties.")
 
 (defvar tramp-cache-inhibit-cache nil
-  "Inhibit cache read access, when non-nil.")
+  "Inhibit cache read access, when `t'.
+`nil' means to accept cache entries unconditionally.  If the
+value is a timestamp (as returned by `current-time'), cache
+entries are not used when they have been written before this
+time.")
 
 (defcustom tramp-persistency-file-name
   (cond
@@ -106,9 +111,21 @@ Returns DEFAULT if not set."
   (let* ((hash (or (gethash vec tramp-cache-data)
                   (puthash vec (make-hash-table :test 'equal)
                            tramp-cache-data)))
-        (value (if (and (null tramp-cache-inhibit-cache) (hash-table-p hash))
-                   (gethash property hash default)
-                 default)))
+        (value (when (hash-table-p hash) (gethash property hash))))
+    (if
+       ;; We take the value only if there is any, and
+       ;; `tramp-cache-inhibit-cache' indicates that it is still
+       ;; valid.  Otherwise, DEFAULT is set.
+       (and (consp value)
+            (or (null tramp-cache-inhibit-cache)
+                (and (consp tramp-cache-inhibit-cache)
+                     (tramp-time-less-p
+                      tramp-cache-inhibit-cache (car value)))))
+       (setq value (cdr value))
+      (setq value default))
+
+    (if (consp tramp-cache-inhibit-cache)
+       (tramp-message vec 1 "%s %s %s" file property value))
     (tramp-message vec 8 "%s %s %s" file property value)
     value))
 
@@ -121,7 +138,8 @@ Returns VALUE."
   (let ((hash (or (gethash vec tramp-cache-data)
                  (puthash vec (make-hash-table :test 'equal)
                           tramp-cache-data))))
-    (puthash property value hash)
+    ;; We put the timestamp there.
+    (puthash property (cons (current-time) value) hash)
     (tramp-message vec 8 "%s %s %s" file property value)
     value))