Improve logging modules and listing #984

Avoid sorting all modules. Only sort enabled modules.  This allows for
cycles to exist within all modules, but they are only seen as a problem if they
actually enabled.

jetty-start/src/main/java/org/eclipse/jetty/start/Main.java

@@ -308,20 +308,9 @@ public class Main
             }
         }
 
-        StartLog.debug("Sorting Modules");
-        try
-        {
-            modules.sort();
-        }
-        catch (Exception e)
-        {
-            throw new UsageException(ERR_BAD_GRAPH,e);
-        }
-
         args.setAllModules(modules);
         List<Module> activeModules = modules.getEnabled();
 
-
         final Version START_VERSION = new Version(StartArgs.VERSION);
 
         for(Module enabled: activeModules)
@@ -466,8 +455,9 @@ public class Main
         {
             invokeMain(cl, args);
         }
-        catch (Exception e)
+        catch (Throwable e)
         {
+            e.printStackTrace();
             usageExit(e,ERR_INVOKE_MAIN,startupArgs.isTestingModeEnabled());
         }
     }

jetty-start/src/main/java/org/eclipse/jetty/start/Modules.java

@@ -168,7 +168,8 @@ public class Modules implements Iterable<Module>
     public void dumpEnabled()
     {
         int i=0;
-        for (Module module:getEnabled())
+        List<Module> enabled = getEnabled();
+        for (Module module:enabled)
         {
             String name=module.getName();
             String index=(i++)+")";
@@ -240,31 +241,31 @@ public class Modules implements Iterable<Module>
         return str.toString();
     }
 
-    public void sort()
+    public List<Module> getEnabled()
     {
+        List<Module> enabled = _modules.stream().filter(m->{return m.isEnabled();}).collect(Collectors.toList());
+
         TopologicalSort<Module> sort = new TopologicalSort<>();
-        for (Module module: _modules)
+        for (Module module: enabled)
         {
             Consumer<String> add = name ->
             {
                 Module dependency = _names.get(name);
-                if (dependency!=null)
+                if (dependency!=null && dependency.isEnabled())
                     sort.addDependency(module,dependency);
                 
                 Set<Module> provided = _provided.get(name);
                 if (provided!=null)
-                    provided.forEach(p->sort.addDependency(module,p));
+                    for (Module p : provided)
+                        if (p.isEnabled())
+                            sort.addDependency(module,p);
             };
             module.getDepends().forEach(add);
             module.getOptional().forEach(add);
         }
-        
-        sort.sort(_modules);
-    }
 
-    public List<Module> getEnabled()
-    {
-        return _modules.stream().filter(m->{return m.isEnabled();}).collect(Collectors.toList());
+        sort.sort(enabled);
+        return enabled;
     }
 
     /** Enable a module
@@ -287,6 +288,12 @@ public class Modules implements Iterable<Module>
     {
         StartLog.debug("enable %s from %s transitive=%b",module,enabledFrom,transitive);
         
+        if (newlyEnabled.contains(module.getName()))
+        {
+            StartLog.debug("Cycle at %s",module);
+            return;
+        }
+        
         // Check that this is not already provided by another module!
         for (String name:module.getProvides())
         {
@@ -341,7 +348,6 @@ public class Modules implements Iterable<Module>
                 {
                     Path file = _baseHome.getPath("modules/" + dependsOn + ".mod");
                     registerModule(file).expandProperties(_args.getProperties());
-                    sort();
                     providers = _provided.get(dependsOn);
                     if (providers==null || providers.isEmpty())
                         throw new UsageException("Module %s does not provide %s",_baseHome.toShortForm(file),dependsOn);

jetty-start/src/main/resources/org/eclipse/jetty/start/usage.txt

@@ -81,7 +81,6 @@ Module Management:
                    Note: this can also be used in the ${jetty.base}/start.ini
                    or ${jetty.base}/start.d/*.ini files.
                    
-  --add=<modulename>(,<modulename>)*
   --add-to-start=<modulename>(,<modulename>)*
                    Add the modules to the list of modules enabled at start. 
                    Transitive dependencies are followed and dependent

jetty-start/src/test/java/org/eclipse/jetty/start/ModuleGraphWriterTest.java

@@ -62,7 +62,6 @@ public class ModuleGraphWriterTest
 
         Modules modules = new Modules(basehome, args);
         modules.registerAll();
-        modules.sort();
 
         Path outputFile = basehome.getBasePath("graph.dot");
 

jetty-start/src/test/java/org/eclipse/jetty/start/ModulesTest.java

@@ -168,7 +168,6 @@ public class ModulesTest
         // Enable 2 modules
         modules.enable("base",TEST_SOURCE);
         modules.enable("optional",TEST_SOURCE);
-        modules.sort();
 
         // Collect active module list
         List<Module> active = modules.getEnabled();

jetty-start/src/test/resources/usecases/dynamic-loop/start.ini

@@ -1 +1 @@
--module=root
+--module=root

jetty-start/src/test/resources/usecases/loop.prepare.txt

@@ -1 +1,2 @@
---create-startd --add=tom
+--create-startd
+--add-to-start=tom

jetty-start/src/test/resources/usecases/loop/start.ini

@@ -1 +1 @@
--module=root
+--module=root