* Switched from explicit cleanup functions to "resource acquisition by definition",

  implemented by the new ScopedResource class. This change improves robustness
  with respect to signals and unexpected errors and makes the code cleaner.

git-svn-id: http://svn.openslx.org/svn/openslx/openslx/trunk@1678 95ad53e4-c205-0410-b2fa-d234c58c8868

2 files changed, 47 insertions, 41 deletions

diff --git a/installer/OpenSLX/OSSetup/Distro/Base.pm b/installer/OpenSLX/OSSetup/Distro/Base.pm
index 39572e5d..573114e8 100644
--- a/installer/OpenSLX/OSSetup/Distro/Base.pm
+++ b/installer/OpenSLX/OSSetup/Distro/Base.pm
@@ -122,11 +122,6 @@ sub startSession
     my $self  = shift;
     my $osDir = shift;
     
-    # ensure that the session will be finished even if the script crashes:
-    addCleanupFunction(
-        "slxos-setup::distro::chroot", sub { $self->finishSession(); }
-    );
-
     # setup a fixed locale environment to avoid warnings about unset locales
     # (like for instance shown by apt-get)
     $ENV{LC_ALL} = 'POSIX';
@@ -152,7 +147,7 @@ sub startSession
 
     # mount /proc (if we have 'mount' available)
     if (qx{which mount 2>/dev/null}) {
-        if (!-e "$osDir/proc" && !mkpath("$osDir/proc")) {
+        if (!-e '/proc' && !mkpath('/proc')) {
             die _tr("unable to create folder '%s' (%s)\n", "$osDir/proc", $!);
         }
         if (slxsystem("mount -t proc proc '/proc'")) {
@@ -160,15 +155,13 @@ sub startSession
         }
     }
 
-    return;
+    return 1;
 }
 
 sub finishSession
 {
     my $self = shift;
     
-    removeCleanupFunction('slxos-setup::distro::chroot');
-
     # umount /proc (if we have 'umount' available)
     if (qx{which umount 2>/dev/null}) {
         if (slxsystem("umount /proc")) {
@@ -176,7 +169,7 @@ sub finishSession
         }
     }
 
-    return;
+    return 1;
 }
 
 sub getDefaultPathList
diff --git a/installer/OpenSLX/OSSetup/Engine.pm b/installer/OpenSLX/OSSetup/Engine.pm
index 9518c74a..7fce8a59 100644
--- a/installer/OpenSLX/OSSetup/Engine.pm
+++ b/installer/OpenSLX/OSSetup/Engine.pm
@@ -31,6 +31,7 @@ use File::Basename;
 use URI;
 
 use OpenSLX::Basics;
+use OpenSLX::ScopedResource;
 use OpenSLX::Syscall;
 use OpenSLX::Utils;
 
@@ -117,8 +118,7 @@ use vars qw(%supportedDistros);
     },
 );
 
-our $localHttpServerMasterPID;
-our %localHttpServers;
+my %localHttpServers;
 
 ################################################################################
 ### interface methods
@@ -132,22 +132,6 @@ sub new
     return bless $self, $class;
 }
 
-sub DESTROY
-{
-    my $self = shift;
-
-    my $httpServerPID = $localHttpServerMasterPID || '0';
-    if ($httpServerPID == $$) {
-        # we are the master process, so we clean up all the servers that we
-        # have started:
-        while (my ($localURL, $serverInfo) = each %localHttpServers) {
-            vlog(1, _tr("stopping local HTTP-server for URL '%s'.", $localURL));
-            kill TERM => $serverInfo->{pid};
-        }
-    }
-    return;
-}
-
 sub initialize
 {
     my $self         = shift;
@@ -291,7 +275,11 @@ sub installVendorOS
     }
     $self->_createVendorOSPath();
 
-    $self->_startLocalURLServersAsNeeded();
+    my $httpServers = OpenSLX::ScopedResource->new({
+        name    => 'local-http-servers',
+        acquire => sub { $self->_startLocalURLServersAsNeeded(); 1 },
+        release => sub { $self->_stopLocalURLServers(); 1 },
+    });
 
     my $baseSystemFile = "$self->{'vendor-os-path'}/.openslx-base-system";
     if (-e $baseSystemFile) {
@@ -436,7 +424,11 @@ sub updateVendorOS
             $self->{'vendor-os-path'});
     }
 
-    $self->_startLocalURLServersAsNeeded();
+    my $httpServers = OpenSLX::ScopedResource->new({
+        name    => 'local-http-servers',
+        acquire => sub { $self->_startLocalURLServersAsNeeded(); 1 },
+        release => sub { $self->_stopLocalURLServers(); 1 },
+    });
 
     callInSubprocess(
         sub {
@@ -467,7 +459,11 @@ sub startChrootedShellForVendorOS
         );
     }
 
-    $self->_startLocalURLServersAsNeeded();
+    my $httpServers = OpenSLX::ScopedResource->new({
+        name    => 'local-http-servers',
+        acquire => sub { $self->_startLocalURLServersAsNeeded(); 1 },
+        release => sub { $self->_stopLocalURLServers(); 1 },
+    });
 
     callInSubprocess(
         sub {
@@ -500,7 +496,11 @@ sub callChrootedFunctionForVendorOS
         );
     }
 
-    $self->_startLocalURLServersAsNeeded();
+    my $httpServers = OpenSLX::ScopedResource->new({
+        name    => 'local-http-servers',
+        acquire => sub { $self->_startLocalURLServersAsNeeded(); 1 },
+        release => sub { $self->_stopLocalURLServers(); 1 },
+    });
 
     callInSubprocess(
         sub {
@@ -1189,8 +1189,6 @@ sub _startLocalURLServersAsNeeded
 {
     my $self = shift;
 
-    $localHttpServerMasterPID ||= $$;
-
     my $port = 5080;
     my %portForURL;
     foreach my $repoInfo (values %{$self->{'distro-info'}->{repository}}) {
@@ -1220,6 +1218,16 @@ sub _startLocalURLServersAsNeeded
     return;
 }
 
+sub _stopLocalURLServers
+{
+    my $self = shift;
+
+    while (my ($localURL, $serverInfo) = each %localHttpServers) {
+        vlog(1, _tr("stopping local HTTP-server for URL '%s'.", $localURL));
+        kill TERM => $serverInfo->{pid};
+    }
+}
+
 sub _setupStage1A
 {
     my $self = shift;
@@ -1582,15 +1590,20 @@ sub _callChrootedFunction
         'updateConfig' => '?',
     });
 
-    $self->{distro}->startSession($params->{chrootDir});
+    my $distro = $self->{distro};
+    my $distroSession = OpenSLX::ScopedResource->new({
+        name    => 'ossetup::distro::session',
+        acquire => sub { $distro->startSession($params->{chrootDir}); 1 },
+        release => sub { $distro->finishSession(); 1 },
+    });
 
-    # invoke given function:
-    $params->{function}->();
+    die $@ if ! eval {
+        # invoke given function:
+        $params->{function}->();
+        $distro->updateDistroConfig() if $params->{updateConfig};
+        1;
+    };
 
-    if ($params->{updateConfig}) {
-        $self->{'distro'}->updateDistroConfig();
-    }
-    $self->{'distro'}->finishSession();
     return;
 }