--- loncom/lonnet/perl/lonnet.pm	2012/11/11 01:48:33	1.1197
+++ loncom/lonnet/perl/lonnet.pm	2012/11/11 17:33:26	1.1198
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1197 2012/11/11 01:48:33 raeburn Exp $
+# $Id: lonnet.pm,v 1.1198 2012/11/11 17:33:26 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -2694,7 +2694,7 @@ sub can_edit_resource {
             my $allowed = 0;
             if ($resurl =~ m{^/?adm/$cdom/$cnum/$group/smppg$}) {
                 if ((&allowed('mdg',$env{'request.course.id'}.
-                            ($env{'request.course.sec'}?'/'.$env{'request.course.sec'}:''))) ||
+                              ($env{'request.course.sec'}?'/'.$env{'request.course.sec'}:''))) ||
                         (&allowed('mgh',$env{'request.course.id'}.'/'.$group)) || $crsedit) {
                     $allowed = 1;
                 }
@@ -5691,6 +5691,88 @@ sub tmpdel {
     return &reply("tmpdel:$token",$server);
 }
 
+# ------------------------------------------------------------ get_timebased_id 
+
+sub get_timebased_id {
+    my ($prefix,$keyid,$namespace,$cdom,$cnum,$idtype,$who,$locktries,
+        $maxtries) = @_;
+    my ($newid,$error,$dellock);
+    unless (($prefix =~ /^\w+$/) && ($keyid =~ /^\w+$/) && ($namespace ne '')) {  
+        return ('','ok','invalid call to get suffix');
+    }
+
+# set defaults for any optional args for which values were not supplied
+    if ($who eq '') {
+        $who = $env{'user.name'}.':'.$env{'user.domain'};
+    }
+    if (!$locktries) {
+        $locktries = 3;
+    }
+    if (!$maxtries) {
+        $maxtries = 10;
+    }
+    
+    if (($cdom eq '') || ($cnum eq '')) {
+        if ($env{'request.course.id'}) {
+            $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
+            $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
+        }
+        if (($cdom eq '') || ($cnum eq '')) {
+            return ('','ok','call to get suffix not in course context');
+        }
+    }
+
+# construct locking item
+    my $lockhash = {
+                      $prefix."\0".'locked_'.$keyid => $who,
+                   };
+    my $tries = 0;
+
+# attempt to get lock on nohist_$namespace file
+    my $gotlock = &Apache::lonnet::newput('nohist_'.$namespace,$lockhash,$cdom,$cnum);
+    while (($gotlock ne 'ok') && $tries <$locktries) {
+        $tries ++;
+        sleep 1;
+        $gotlock = &Apache::lonnet::newput('nohist_'.$namespace,$lockhash,$cdom,$cnum);
+    }
+
+# attempt to get unique identifier, based on current timestamp
+    if ($gotlock eq 'ok') {
+        my %inuse = &Apache::lonnet::dump('nohist_'.$namespace,$cdom,$cnum,$prefix);
+        my $id = time;
+        $newid = $id;
+        my $idtries = 0;
+        while (exists($inuse{$prefix."\0".$newid}) && $idtries < $maxtries) {
+            if ($idtype eq 'concat') {
+                $newid = $id.$idtries;
+            } else {
+                $newid ++;
+            }
+            $idtries ++;
+        }
+        if (!exists($inuse{$prefix."\0".$newid})) {
+            my %new_item =  (
+                              $prefix."\0".$newid => $who,
+                            );
+            my $putresult = &Apache::lonnet::put('nohist_'.$namespace,\%new_item,
+                                                 $cdom,$cnum);
+            if ($putresult ne 'ok') {
+                undef($newid);
+                $error = 'error saving new item: '.$putresult;
+            }
+        } else {
+             $error = ('error: no unique suffix available for the new item ');
+        }
+#  remove lock
+        my @del_lock = ($prefix."\0".'locked_'.$keyid);
+        $dellock = &Apache::lonnet::del('nohist_'.$namespace,\@del_lock,$cdom,$cnum);
+    } else {
+        $error = "error: could not obtain lockfile\n";
+        $dellock = 'ok';
+    }
+    return ($newid,$dellock,$error);
+}
+
 # -------------------------------------------------- portfolio access checking
 
 sub portfolio_access {
@@ -13216,6 +13298,8 @@ Internal notes:
  
  Locks on files (resulting from submission of portfolio file to a homework problem stored in array of arrays.
 
+=item *
+
 modify_access_controls():
 
 Modifies access controls for a portfolio file
@@ -13233,7 +13317,51 @@ Returns:
 3. reference to hash of any new or updated access controls.
 4. reference to hash used to map incoming IDs to uniqueIDs assigned to control.
    key = integer (inbound ID)
-   value = uniqueID  
+   value = uniqueID
+
+=item *
+
+get_timebased_id():
+
+Attempts to get a unique timestamp-based suffix for use with items added to a 
+course via the Course Editor (e.g., folders, composite pages, 
+group bulletin boards).
+
+Args: (first three required; six others optional)
+
+1. prefix (alphanumeric): of keys in hash, e.g., suppsequence, docspage,
+   docssequence, or name of group
+
+2. keyid (alphanumeric): name of temporary locking key in hash,
+   e.g., num, boardids
+
+3. namespace: name of gdbm file used to store suffixes already assigned;  
+   file will be named nohist_namespace.db
+
+4. cdom: domain of course; default is current course domain from %env
+
+5. cnum: course number; default is current course number from %env
+
+6. idtype: set to concat if an additional digit is to be appended to the 
+   unix timestamp to form the suffix, if the plain timestamp is already
+   in use.  Default is to not do this, but simply increment the unix 
+   timestamp by 1 until a unique key is obtained.
+
+7. who: holder of locking key; defaults to user:domain for user.
+
+8. locktries: number of attempts to obtain a lock (sleep of 1s before 
+   retrying); default is 3.
+
+9. maxtries: number of attempts to obtain a unique suffix; default is 20.  
+
+Returns:
+
+1. suffix obtained (numeric)
+
+2. result of deleting locking key (ok if deleted, or lock never obtained)
+
+3. error: contains (localized) error message if an error occurred.
+
 
 =back