openwebwork-cvs

[Sam H. v. a. <we...@ma...>]

Log Message:
-----------
HEAD backport: expansion of Mike's caching fixes. (sh002i)

Tags:
----
rel-2-1-patches

Modified Files:
--------------
    webwork2/lib:
        WeBWorK.pm
    webwork2/lib/WeBWorK:
        Authz.pm

Revision Data
-------------
Index: WeBWorK.pm
===================================================================
RCS file: /webwork/cvs/system/webwork2/lib/WeBWorK.pm,v
retrieving revision 1.68.2.1
retrieving revision 1.68.2.2
diff -Llib/WeBWorK.pm -Llib/WeBWorK.pm -u -r1.68.2.1 -r1.68.2.2
--- lib/WeBWorK.pm
+++ lib/WeBWorK.pm
@@ -224,7 +224,7 @@
 		}
 		
 		debug("Create an authz object (Authen needs it to check login permission)...\n");
-		$authz = new WeBWorK::Authz($r, $ce, $db);
+		$authz = new WeBWorK::Authz($r);
 		debug("(here's the authz object: $authz)\n");
 		$r->authz($authz);
 		
@@ -234,6 +234,9 @@
 		if ($authenOK) {
 			my $userID = $r->param("user");
 			debug("Hi, $userID, glad you made it.\n");
+			
+			# tell authorizer to cache this user's permission level
+			$authz->setCachedUser($userID);
 			
 			debug("Now we deal with the effective user:\n");
 			my $eUserID = $r->param("effectiveUser") || $userID;
Index: Authz.pm
===================================================================
RCS file: /webwork/cvs/system/webwork2/lib/WeBWorK/Authz.pm,v
retrieving revision 1.17.2.1
retrieving revision 1.17.2.2
diff -Llib/WeBWorK/Authz.pm -Llib/WeBWorK/Authz.pm -u -r1.17.2.1 -r1.17.2.2
--- lib/WeBWorK/Authz.pm
+++ lib/WeBWorK/Authz.pm
@@ -20,52 +20,184 @@
 
 WeBWorK::Authz - check user permissions.
 
+=head1 SYNOPSIS
+
+ # create new authorizer -- $r is a WeBWorK::Request object.
+ my $authz = new WeBWorK::Authz($r);
+ 
+ # tell authorizer to cache permission level of user spammy.
+ $authz->setCachedUser("spammy");
+ 
+ # this call will use the cached data.
+ if ($authz->hasPermissions("spammy", "eat_breakfast")) {
+ 	eat_breakfast();
+ }
+ 
+ # this call will not use the cached data, and will cause a database lookup.
+ if ($authz->hasPermissions("hammy", "go_to_bed")) {
+ 	go_to_bed();
+ }
+
+=head1 DESCRIPTION
+
+WeBWorK::Authen determines if a user is authorized to perform a specific
+activity, based on the user's PermissionLevel record in the WeBWorK database and
+the contents of the %permissionLevels hash in the course environment.
+
+=head2 Format of the %permissionLevels hash
+
+%permissionLevels maps text strings describing activities to numeric permission
+levels. The definitive list of activities is contained in the default version of
+%permissionLevels, in the file F<conf/global.conf.dist>.
+
+A user is able to engage in an activity if their permission level is greater
+than or equal to the level associated with the activity. If the level associated
+with an activity is undefiend, then no user is permitted to perform the
+activity, regardless of their permission level.
+
 =cut
 
 use strict;
 use warnings;
 
+################################################################################
+
+=head1 CONSTRUCTOR
+
+=over
+
+=item WeBWorK::Authz->new($r)
+
+Creates a new authorizer instance. $r is a WeBWorK::Request object. It must
+already have its C<ce> and C<db> fields set.
+
+=cut
 
 sub new {
-	my ($invocant, $r, $ce, $db) = @_;
+	my ($invocant, $r) = @_;
 	my $class = ref($invocant) || $invocant;
 	my $self = {
 		r => $r,
 	};
 	
-	my $user = $r->param("user");   
-	return 0 unless defined($user);
-	my $Permission = $db->getPermissionLevel($user); # checked
-	return 0 unless defined $Permission;
-	my $permissionLevel = $Permission->permission();
-	return 0 unless defined $permissionLevel and $permissionLevel ne "";
-	
-	my $permissionLevels = $ce->{permissionLevels};
-	$self->{permissionLevels} = $permissionLevels;
-	$self->{permissionLevel}  = $permissionLevel;
 	bless $self, $class;
 	return $self;
 }
 
-# This module assumes that neither the permissionLevels nor the permissionLevel
-# changes between the time an authz module is created and the time it's used.
+=back
+
+=cut
+
+################################################################################
+
+=head1 METHODS
+
+=over
+
+=item setCachedUser($userID)
+
+Caches the PermissionLevel of the user $userID in an existing authorizer. If a
+user's PermissionLevel is cached, it will be used whenever hasPermissions() is
+called on the same user. Only one user can be cached at a time. This is used by
+WeBWorK to cache the "real" user.
+
+=cut
+
+sub setCachedUser {
+	my ($self, $userID) = @_;
+	my $r = $self->{r};
+	my $db = $r->db;
+	
+	delete $self->{userID};
+	delete $self->{PermissionLevel};
+	
+	if (defined $userID) {
+		$self->{userID} = $userID;
+		my $PermissionLevel = $db->getPermissionLevel($userID); # checked
+		if (defined $PermissionLevel) {
+			# store permission level record in database to avoid later database calls
+			$self->{PermissionLevel} = $PermissionLevel;
+		}
+	} else {
+		warn "setCachedUser() called with userID undefined.\n";
+	}
+}
+
+=item hasPermissions($userID, $activity)
+
+Checks the %permissionLevels hash in the course environment to determine if the
+user $userID has permission to engage in the activity $activity. If the user's
+permission level is greater than or equal to the level associated with $activty,
+a true value is returned. Otherwise, a false value is returned.
+
+If $userID has been cached using the setCachedUser() call, the cached data is
+used. Otherwise, the user's PermissionLevel is looked up in the WeBWorK
+database.
+
+If the user does not have a PermissionLevel record, the permission level record
+is empty, or the activity does not appear in %permissionLevels, hasPermissions()
+assumes that the user does not have permission.
+
+=cut
 
 # This currently only uses two of it's arguments, but it accepts any number, in
 # case in the future calculating certain permissions requires more information.
 sub hasPermissions {
-	my ($self, $user, $activity) = @_;
-	my $permissionLevels = $self->{permissionLevels};
-	my $permissionLevel = $self->{permissionLevel};
+	my ($self, $userID, $activity) = @_;
+	my $r = $self->{r};
+	my $ce = $r->ce;
+	my $db = $r->db;
+	
+	my $PermissionLevel;
+	
+	my $cachedUserID = $self->{userID};
+	if (defined $cachedUserID and $cachedUserID ne "" and $cachedUserID eq $userID) {
+		# this is the same user -- we can skip the database call
+		$PermissionLevel = $self->{PermissionLevel};
+	} else {
+		# a different user, or no user was defined before
+		my $prettyCachedUserID = defined $cachedUserID ? "'$cachedUserID'" : "undefined";
+		#warn "hasPermissions called with user '$userID', but cached user is $prettyCachedUserID. Accessing database.\n";
+		$PermissionLevel = $db->getPermissionLevel($userID); # checked
+	}
+	
+	my $permission_level;
+	
+	if (defined $PermissionLevel) {
+		$permission_level = $PermissionLevel->permission;
+	} else {
+		# uh, oh. this user has no permission level record!
+		warn "User '$userID' has no PermissionLevel record -- assuming no permission.\n";
+		return 0;
+	}
+	
+	unless (defined $permission_level and $permission_level ne "") {
+		warn "User '$userID' has empty permission level -- assuming no permission.\n";
+		return 0;
+	}
+	
+	my $permissionLevels = $ce->{permissionLevels};
 	if (exists $permissionLevels->{$activity}) {
 		if (defined $permissionLevels->{$activity}) {
-			return $permissionLevel >= $permissionLevels->{$activity};
+			return $permission_level >= $permissionLevels->{$activity};
 		} else {
-			return 0;
+			return 0; # nobody has permission to do this
 		}
 	} else {
-		die "Activity '$activity' not found in %permissionLevels. Can't continue.\n";
+		warn "Activity '$activity' not found in %permissionLevels -- assuming no permission.\n";
+		return 0;
 	}
-
 }
+
+=back
+
+=cut
+
+=head1 AUTHOR
+
+Written by Dennis Lambe, malsyned at math.rochester.edu. Modified by Sam
+Hathaway, sh002i at math.rochester.edu.
+
+=cut
 
 1;