[Emacs-diffs] /srv/bzr/emacs/trunk r101765: * files.texi (Magic File Names): New defopt remote-file-name-inhibit-cache.

[Michael Albinus]

------------------------------------------------------------
revno: 101765
committer: Michael Albinus <address@hidden>
branch nick: trunk
timestamp: Sun 2010-10-03 17:58:09 +0200
message:
  * files.texi (Magic File Names): New defopt remote-file-name-inhibit-cache.
modified:
  doc/lispref/ChangeLog
  doc/lispref/files.texi

=== modified file 'doc/lispref/ChangeLog'
--- a/doc/lispref/ChangeLog     2010-10-02 02:30:11 +0000
+++ b/doc/lispref/ChangeLog     2010-10-03 15:58:09 +0000
@@ -1,3 +1,8 @@
+2010-10-03  Michael Albinus  <address@hidden>
+
+       * files.texi (Magic File Names): New defopt
+       remote-file-name-inhibit-cache.
+
 2010-10-02  Glenn Morris  <address@hidden>
 
        * os.texi (Killing Emacs): Hook now runs in batch mode.

=== modified file 'doc/lispref/files.texi'
--- a/doc/lispref/files.texi    2010-09-05 22:03:56 +0000
+++ b/doc/lispref/files.texi    2010-10-03 15:58:09 +0000
@@ -2857,6 +2857,34 @@
 is a good way to come up with one.
 @end defun
 
address@hidden remote-file-name-inhibit-cache
+Whether to use the remote file-name cache for read access.
+
+File attributes of remote files are cached for better performance.  If
+they are changed out of Emacs' control, the cached values become
+invalid, and must be reread.
+
+When set to @code{nil}, cached values are always used.  This shall be
+set with care.  When set to @code{t}, cached values are never used.
+ALthough this is the safest value, it could result in performance
+degradation.
+
+A compromise is to set it to a positive number.  This means that
+cached values are used for that amount of seconds since they were
+cached.
+
+In case a remote file is checked regularly, it might be reasonable to
+let-bind this variable to a value less then the time period between
+two checks.  Example:
+
address@hidden
+(defun display-time-file-nonempty-p (file)
+  (let ((remote-file-name-inhibit-cache (- display-time-interval 5)))
+    (and (file-exists-p file)
+         (< 0 (nth 7 (file-attributes (file-chase-links file)))))))
address@hidden example
address@hidden defopt
+
 @node Format Conversion
 @section File Format Conversion