Add option to list disabled plugins

After disabling a plugin, it can now be viewed in the ls command by
specifying the --all (-a) argument.  This will be more useful once
we add an ssh command to re-enabled plugins which are disabled.

Change-Id: I4100cd9df4ebfac87b2099ef2c916b99ef55c978
Signed-off-by: Brad Larson <bklarson@gmail.com>

gerrit-server/src/main/java/com/google/gerrit/server/plugins/ListPlugins.java

@@ -40,6 +40,9 @@ public class ListPlugins {
   @Option(name = "--format", metaVar = "FMT", usage = "Output display format")
   private OutputFormat format = OutputFormat.TEXT;
 
+  @Option(name = "--all", aliases = {"-a"}, usage = "List all plugins, including disabled plugins")
+  private boolean all;
+
   @Inject
   protected ListPlugins(PluginLoader pluginLoader) {
     this.pluginLoader = pluginLoader;
@@ -67,7 +70,7 @@ public class ListPlugins {
 
     Map<String, PluginInfo> output = Maps.newTreeMap();
 
-    List<Plugin> plugins = Lists.newArrayList(pluginLoader.getPlugins());
+    List<Plugin> plugins = Lists.newArrayList(pluginLoader.getPlugins(all));
     Collections.sort(plugins, new Comparator<Plugin>() {
       @Override
       public int compare(Plugin a, Plugin b) {
@@ -76,20 +79,22 @@ public class ListPlugins {
     });
 
     if (!format.isJson()) {
-      stdout.format("%-30s %-10s\n", "Name", "Version");
+      stdout.format("%-30s %-10s %-8s\n", "Name", "Version", "Status");
       stdout
-          .print("----------------------------------------------------------------------\n");
+          .print("-------------------------------------------------------------------------------\n");
     }
 
     for (Plugin p : plugins) {
       PluginInfo info = new PluginInfo();
       info.version = p.getVersion();
+      info.disabled = p.isDisabled() ? true : null;
 
       if (format.isJson()) {
         output.put(p.getName(), info);
       } else {
-        stdout.format("%-30s %-10s\n", p.getName(),
-            Strings.nullToEmpty(info.version));
+        stdout.format("%-30s %-10s %-8s\n", p.getName(),
+            Strings.nullToEmpty(info.version),
+            p.isDisabled() ? "DISABLED" : "");
       }
     }
 
@@ -103,5 +108,9 @@ public class ListPlugins {
 
   private static class PluginInfo {
     String version;
+    // disabled is only read via reflection when building the json output.  We
+    // do not want to show a compiler error that it isn't used.
+    @SuppressWarnings("unused")
+    Boolean disabled;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/plugins/Plugin.java

@@ -89,6 +89,7 @@ public class Plugin {
   private final File dataDir;
   private final ApiType apiType;
   private final ClassLoader classLoader;
+  private final boolean disabled;
   private Class<? extends Module> sysModule;
   private Class<? extends Module> sshModule;
   private Class<? extends Module> httpModule;
@@ -119,6 +120,7 @@ public class Plugin {
     this.dataDir = dataDir;
     this.apiType = apiType;
     this.classLoader = classLoader;
+    this.disabled = srcJar.getName().endsWith(".disabled");
     this.sysModule = sysModule;
     this.sshModule = sshModule;
     this.httpModule = httpModule;
@@ -165,6 +167,10 @@ public class Plugin {
     return snapshot.lastModified() != jar.lastModified();
   }
 
+  public boolean isDisabled() {
+    return disabled;
+  }
+
   public void start(PluginGuiceEnvironment env) throws Exception {
     Injector root = newRootInjector(env);
     manager = new LifecycleManager();
@@ -294,13 +300,15 @@ public class Plugin {
   }
 
   public void add(RegistrationHandle handle) {
-    if (handle instanceof ReloadableRegistrationHandle) {
-      if (reloadableHandles == null) {
-        reloadableHandles = Lists.newArrayList();
+    if (manager != null) {
+      if (handle instanceof ReloadableRegistrationHandle) {
+        if (reloadableHandles == null) {
+          reloadableHandles = Lists.newArrayList();
+        }
+        reloadableHandles.add((ReloadableRegistrationHandle<?>) handle);
       }
-      reloadableHandles.add((ReloadableRegistrationHandle<?>) handle);
+      manager.add(handle);
     }
-    manager.add(handle);
   }
 
   List<ReloadableRegistrationHandle<?>> getReloadableHandles() {

gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginLoader.java

@@ -45,6 +45,7 @@ import java.lang.ref.ReferenceQueue;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
@@ -67,6 +68,7 @@ public class PluginLoader implements LifecycleListener {
   private final PluginGuiceEnvironment env;
   private final ServerInformationImpl srvInfoImpl;
   private final ConcurrentMap<String, Plugin> running;
+  private final ConcurrentMap<String, Plugin> disabled;
   private final Map<String, FileSnapshot> broken;
   private final ReferenceQueue<ClassLoader> cleanupQueue;
   private final ConcurrentMap<CleanupHandle, Boolean> cleanupHandles;
@@ -85,6 +87,7 @@ public class PluginLoader implements LifecycleListener {
     env = pe;
     srvInfoImpl = sii;
     running = Maps.newConcurrentMap();
+    disabled = Maps.newConcurrentMap();
     broken = Maps.newHashMap();
     cleanupQueue = new ReferenceQueue<ClassLoader>();
     cleanupHandles = Maps.newConcurrentMap();
@@ -100,8 +103,14 @@ public class PluginLoader implements LifecycleListener {
     }
   }
 
-  public Iterable<Plugin> getPlugins() {
-    return running.values();
+  public Iterable<Plugin> getPlugins(boolean all) {
+    if (!all) {
+      return running.values();
+    } else {
+      ArrayList<Plugin> plugins = new ArrayList<Plugin>(running.values());
+      plugins.addAll(disabled.values());
+      return plugins;
+    }
   }
 
   public void installPluginFromStream(String name, InputStream in)
@@ -178,6 +187,15 @@ public class PluginLoader implements LifecycleListener {
 
         active.stop();
         running.remove(name);
+        try {
+          FileSnapshot snapshot = FileSnapshot.save(off);
+          Plugin offPlugin = loadPlugin(name, off, snapshot);
+          disabled.put(name, offPlugin);
+        } catch (Throwable e) {
+          // This shouldn't happen, as the plugin was loaded earlier.
+          log.warn(String.format("Cannot load disabled plugin %s", name),
+              e.getCause());
+        }
       }
       cleanInBackground();
     }
@@ -205,6 +223,7 @@ public class PluginLoader implements LifecycleListener {
         p.stop();
       }
       running.clear();
+      disabled.clear();
       broken.clear();
       if (cleanupHandles.size() > running.size()) {
         System.gc();
@@ -250,6 +269,7 @@ public class PluginLoader implements LifecycleListener {
   public synchronized void rescan() {
     List<File> jars = scanJarsInPluginsDirectory();
     stopRemovedPlugins(jars);
+    dropRemovedDisabledPlugins(jars);
 
     for (File jar : jars) {
       String name = nameOf(jar);
@@ -292,14 +312,20 @@ public class PluginLoader implements LifecycleListener {
         oldPlugin.stop();
         running.remove(name);
       }
-      newPlugin.start(env);
+      if (!newPlugin.isDisabled()) {
+        newPlugin.start(env);
+      }
       if (reload) {
         env.onReloadPlugin(oldPlugin, newPlugin);
         oldPlugin.stop();
-      } else {
+      } else if (!newPlugin.isDisabled()) {
         env.onStartPlugin(newPlugin);
       }
-      running.put(name, newPlugin);
+      if (!newPlugin.isDisabled()) {
+        running.put(name, newPlugin);
+      } else {
+        disabled.put(name, newPlugin);
+      }
       broken.remove(name);
     } catch (Throwable err) {
       broken.put(name, snapshot);
@@ -318,6 +344,16 @@ public class PluginLoader implements LifecycleListener {
     }
   }
 
+  private void dropRemovedDisabledPlugins(List<File> jars) {
+    Set<String> unload = Sets.newHashSet(disabled.keySet());
+    for (File jar : jars) {
+      unload.remove(nameOf(jar));
+    }
+    for (String name : unload) {
+      disabled.remove(name);
+    }
+  }
+
   synchronized int processPendingCleanups() {
     CleanupHandle h;
     while ((h = (CleanupHandle) cleanupQueue.poll()) != null) {
@@ -336,6 +372,9 @@ public class PluginLoader implements LifecycleListener {
 
   private static String nameOf(File jar) {
     String name = jar.getName();
+    if (name.endsWith(".disabled")) {
+      name = name.substring(0, name.lastIndexOf('.'));
+    }
     int ext = name.lastIndexOf('.');
     return 0 < ext ? name.substring(0, ext) : name;
   }
@@ -430,7 +469,9 @@ public class PluginLoader implements LifecycleListener {
     File[] matches = pluginsDir.listFiles(new FileFilter() {
       @Override
       public boolean accept(File pathname) {
-        return pathname.getName().endsWith(".jar") && pathname.isFile();
+        String n = pathname.getName();
+        return (n.endsWith(".jar") || n.endsWith(".jar.disabled"))
+            && pathname.isFile();
       }
     });
     if (matches == null) {