* Instead of an error when the users file doesn't exist, just show a

warning in the log file.
* Use 'timestamp for reading preference files.

svn: r16174

collects/handin-server/checker.ss

@@ -40,9 +40,10 @@
 
 (provide user-data)
 (define (user-data user)
-  ;; the student always assumed to exist
+  ;; the student is always assumed to exist
   (cdr (get-preference (if (string? user) (string->symbol user) user)
-                       (lambda () #f) #f (build-path server-dir "users.ss"))))
+                       (lambda () #f) 'timestamp
+                       (build-path server-dir "users.ss"))))
 
 (provide user-substs)
 (define (user-substs user str)

collects/handin-server/main.ss

@@ -325,7 +325,8 @@
    orig-custodian))
 
 (define (get-user-data username)
-  (get-preference (string->symbol username) (lambda () #f) #f "users.ss"))
+  (get-preference (string->symbol username) (lambda () #f) 'timestamp
+                  "users.ss"))
 (define (check-field value field-re field-name field-desc)
   (unless (cond [(or (string? field-re) (regexp? field-re))
                  (regexp-match field-re value)]

collects/handin-server/web-status-server.ss

@@ -24,9 +24,10 @@
 (define get-user-data
   (let ([users-file (build-path server-dir "users.ss")])
     (unless (file-exists? users-file)
-      (error 'get-user-data "users file missing at: ~a" users-file))
+      (log-line "WARNING: users file missing on startup: ~a" users-file))
     (lambda (user)
-      (get-preference (string->symbol user) (lambda () #f) #f users-file))))
+      (get-preference (string->symbol user) (lambda () #f) 'timestamp
+                      users-file))))
 
 (define (relativize-path p)
   (path->string (find-relative-path (normalize-path server-dir) p)))