--- loncom/homework/bridgetask.pm	2005/12/21 19:10:33	1.93
+++ loncom/homework/bridgetask.pm	2006/01/26 07:12:38	1.98
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # definition of tags that give a structure to a document
 #
-# $Id: bridgetask.pm,v 1.93 2005/12/21 19:10:33 albertel Exp $
+# $Id: bridgetask.pm,v 1.98 2006/01/26 07:12:38 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -554,6 +554,8 @@ DONESCREEN
 		    $result.=&show_queue($env{'form.queue'},1);
 		} elsif ($status_code eq 'select_user') {
 		    $result.=&select_user();
+		} elsif ($status_code eq 'unable') {
+		    $result.='<b>'.&mt("Unable to aqcuire a user to grade.").'</b>'.$back;
 		} else {
 		    $result.='<b>'.&mt("No user to be graded.").'</b>'.$back;
 		}
@@ -689,6 +691,17 @@ sub get_key_todo {
     }
     return (undef,undef)
 }
+
+sub minimize_storage {
+    foreach my $key (keys(%Apache::lonhomework::results)) {
+	if ($key =~ /regrader$/) { next; }
+	if ($Apache::lonhomework::results{$key} eq
+	    $Apache::lonhomework::history{$key}) {
+	    delete($Apache::lonhomework::results{$key});
+	}
+    }
+}
+
 sub end_Task {
     my ($target,$token,$tagstack,$parstack,$parser,$safeeval)=@_;
     my $result='';
@@ -897,6 +910,7 @@ DONEBUTTON
 		$Apache::lonhomework::results{"resource.0.solved"}=
 		    $Apache::lonhomework::results{"resource.$version.0.solved"};
 	    }
+	    &minimize_storage();
 	    &Apache::structuretags::finalize_storage();
 	}
     } elsif ($target eq 'webgrade') {
@@ -1166,6 +1180,7 @@ sub get_queue_counts {
 	return (0,0,0);
     }
     my ($entries,$ready_to_grade,$locks)=(0,0,0);
+    my %slot_cache;
     foreach my $key (sort(keys(%queue))) {
 	if ($key=~/locked$/) {
 	    $locks++;
@@ -1175,8 +1190,11 @@ sub get_queue_counts {
 	    my ($symb,$uname,$udom) = &decode_queue_key($key);
 	    $entries++;
 	    my $slot=$queue{$key}->[0];
-	    my %slot_data=&Apache::lonnet::get_slot($slot);
-	    if (time > $slot_data{'endtime'}) {
+	    if (!exists($slot_cache{$slot})) {
+		my %slot_data=&Apache::lonnet::get_slot($slot);
+		$slot_cache{$slot} = \%slot_data;
+	    }
+	    if (time > $slot_cache{$slot}{'endtime'}) {
 		$ready_to_grade++;
 	    }
 	}
@@ -1213,6 +1231,7 @@ sub queue_key_locked {
 
 sub pick_from_queue_data {
     my ($queue,$check_section,$queuedata,$cdom,$cnum)=@_;
+    my @possible; # will hold queue entries that are valid to be selected
     foreach my $key (keys(%$queuedata)) {
 	if ($key =~ /\0locked$/) { next; }
 	if ($key =~ /\0timestamp$/) { next; }
@@ -1230,11 +1249,18 @@ sub pick_from_queue_data {
 	    &Apache::lonxml::debug("not time");
 	    next;
 	}
-	if (&queue_key_locked($queue,$key,$cdom,$cnum)) {
+	if (exists($queuedata->{"$key\0locked"})) {
 	    &Apache::lonxml::debug("someone already has um.");
 	    next;
 	}
-	return $key;
+	push(@possible,[$key,$slot_data{'endtime'}]);
+    }
+    if (@possible) {
+        # sort entries in order by slot end time
+	@possible = sort { $a->[1] <=> $b->[1] } @possible;
+	# pick one of the first ten entries
+	my $max=($#possible < 10) ? $#possible : 10;
+	return $possible[int(rand($max))][0];
     }
     return undef;
 }
@@ -1305,12 +1331,19 @@ sub get_from_queue {
     my $todo=&find_mid_grade($queue,$symb,$cdom,$cnum);
     &Apache::lonxml::debug("found ".join(':',&decode_queue_key($todo)));
     if ($todo) { return $todo; }
+    my $attempts=0;
     while (1) {
+	if ($attempts > 2) {
+	    # tried twice to get a queue entry, giving up
+	    return (undef,'unable');
+	}
 	my $starttime=time;
 	&Apache::lonnet::cput($queue,{"$symb\0timestamp"=>$starttime},
 			      $cdom,$cnum);
 	&Apache::lonxml::debug("$starttime");
 	my $regexp="^$symb\0queue\0";
+	my $range= ($attempts < 1 ) ? '0-100' : '0-400';
+
 	my %queue=&Apache::lonnet::dump($queue,$cdom,$cnum,$regexp);
 	#make a pass looking for a user _not_ in my section
 	if ($env{'request.course.sec'}) {
@@ -1323,8 +1356,7 @@ sub get_from_queue {
 	# ready for grading
 	if (!$todo) {
 	    &Apache::lonxml::debug("no sce");
-	    $todo=&pick_from_queue_data($queue,$env{'request.course.sec'},
-					\%queue,$cdom,$cnum);
+	    $todo=&pick_from_queue_data($queue,undef,\%queue,$cdom,$cnum);
 	    &Apache::lonxml::debug("no sce $todo");
 	}
 	# no user to grade 
@@ -1332,7 +1364,10 @@ sub get_from_queue {
 	&Apache::lonxml::debug("got $todo");
 	# otherwise found someone so lets try to lock them
 	# unless someone else already picked them
-	if (!&lock_key($queue,$todo)) { next; }
+	if (!&lock_key($queue,$todo)) {
+	    $attempts++;
+	    next;
+	}
 	my (undef,$endtime)=
 	    &Apache::lonnet::get($queue,["$symb\0timestamp"],
 				 $cdom,$cnum);
@@ -1351,6 +1386,7 @@ sub get_from_queue {
 		&Apache::lonnet::del($queue,["$todo\0locked"],
 				     $cdom,$cnum);
 		&Apache::lonxml::debug("del");
+		$attempts++;
 		next;
 	    }
 	}