implemented restarter to move control over the restart process to the core

scm-webapp/src/main/java/sonia/scm/lifecycle/DefaultRestarter.java

@@ -0,0 +1,41 @@
+package sonia.scm.lifecycle;
+
+import com.google.common.annotations.VisibleForTesting;
+import sonia.scm.event.ScmEventBus;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+@Singleton
+public class DefaultRestarter implements Restarter {
+
+  private ScmEventBus eventBus;
+  private RestartStrategy strategy;
+
+  @Inject
+  public DefaultRestarter() {
+    this(
+      ScmEventBus.getInstance(),
+      RestartStrategy.get(Thread.currentThread().getContextClassLoader()).orElse(null)
+    );
+  }
+
+  @VisibleForTesting
+  DefaultRestarter(ScmEventBus eventBus, RestartStrategy strategy) {
+    this.eventBus = eventBus;
+    this.strategy = strategy;
+  }
+
+  @Override
+  public boolean isSupported() {
+    return strategy != null;
+  }
+
+  @Override
+  public void restart(Class<?> cause, String reason) {
+    if (!isSupported()) {
+      throw new RestartNotSupportedException("restarting is not supported");
+    }
+    eventBus.post(new RestartEvent(cause, reason));
+  }
+}

scm-webapp/src/main/java/sonia/scm/lifecycle/RestartNotSupportedException.java

@@ -1,10 +0,0 @@
-package sonia.scm.lifecycle;
-
-/**
- * Exception is thrown if a restart is not supported or a restart strategy is misconfigured.
- */
-public class RestartNotSupportedException extends RuntimeException {
-  RestartNotSupportedException(String message, Throwable cause) {
-    super(message, cause);
-  }
-}

scm-webapp/src/main/java/sonia/scm/lifecycle/modules/BootstrapModule.java

@@ -9,6 +9,8 @@ import sonia.scm.SCMContext;
 import sonia.scm.SCMContextProvider;
 import sonia.scm.io.DefaultFileSystem;
 import sonia.scm.io.FileSystem;
+import sonia.scm.lifecycle.DefaultRestarter;
+import sonia.scm.lifecycle.Restarter;
 import sonia.scm.plugin.PluginLoader;
 import sonia.scm.repository.RepositoryLocationResolver;
 import sonia.scm.repository.xml.MetadataStore;
@@ -61,6 +63,8 @@ public class BootstrapModule extends AbstractModule {
 
     bind(FileSystem.class, DefaultFileSystem.class);
 
+    bind(Restarter.class, DefaultRestarter.class);
+
     // note CipherUtil uses an other generator
     bind(CipherHandler.class).toInstance(CipherUtil.getInstance().getCipherHandler());
 

scm-webapp/src/main/java/sonia/scm/plugin/DefaultPluginManager.java

@@ -41,6 +41,7 @@ import org.slf4j.LoggerFactory;
 import sonia.scm.NotFoundException;
 import sonia.scm.event.ScmEventBus;
 import sonia.scm.lifecycle.RestartEvent;
+import sonia.scm.lifecycle.Restarter;
 import sonia.scm.version.Version;
 
 import javax.inject.Inject;
@@ -68,20 +69,21 @@ public class DefaultPluginManager implements PluginManager {
 
   private static final Logger LOG = LoggerFactory.getLogger(DefaultPluginManager.class);
 
-  private final ScmEventBus eventBus;
   private final PluginLoader loader;
   private final PluginCenter center;
   private final PluginInstaller installer;
+  private final Restarter restarter;
+
   private final Collection<PendingPluginInstallation> pendingInstallQueue = new ArrayList<>();
   private final Collection<PendingPluginUninstallation> pendingUninstallQueue = new ArrayList<>();
   private final PluginDependencyTracker dependencyTracker = new PluginDependencyTracker();
 
   @Inject
-  public DefaultPluginManager(ScmEventBus eventBus, PluginLoader loader, PluginCenter center, PluginInstaller installer) {
-    this.eventBus = eventBus;
+  public DefaultPluginManager(PluginLoader loader, PluginCenter center, PluginInstaller installer, Restarter restarter) {
     this.loader = loader;
     this.center = center;
     this.installer = installer;
+    this.restarter = restarter;
 
     this.computeInstallationDependencies();
   }
@@ -242,16 +244,8 @@ public class DefaultPluginManager implements PluginManager {
     }
   }
 
-  @VisibleForTesting
-  void triggerRestart(String cause) {
-    new Thread(() -> {
-      try {
-        Thread.sleep(200);
-      } catch (InterruptedException e) {
-        Thread.currentThread().interrupt();
-      }
-      eventBus.post(new RestartEvent(PluginManager.class, cause));
-    }).start();
+  private void triggerRestart(String cause) {
+    restarter.restart(PluginManager.class, cause);
   }
 
   private void cancelPending(List<PendingPluginInstallation> pendingInstallations) {

scm-webapp/src/main/java/sonia/scm/update/MigrationWizardServlet.java

@@ -12,6 +12,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import sonia.scm.event.ScmEventBus;
 import sonia.scm.lifecycle.RestartEvent;
+import sonia.scm.lifecycle.Restarter;
 import sonia.scm.update.repository.DefaultMigrationStrategyDAO;
 import sonia.scm.update.repository.MigrationStrategy;
 import sonia.scm.update.repository.V1Repository;
@@ -41,11 +42,13 @@ class MigrationWizardServlet extends HttpServlet {
 
   private final XmlRepositoryV1UpdateStep repositoryV1UpdateStep;
   private final DefaultMigrationStrategyDAO migrationStrategyDao;
+  private final Restarter restarter;
 
   @Inject
-  MigrationWizardServlet(XmlRepositoryV1UpdateStep repositoryV1UpdateStep, DefaultMigrationStrategyDAO migrationStrategyDao) {
+  MigrationWizardServlet(XmlRepositoryV1UpdateStep repositoryV1UpdateStep, DefaultMigrationStrategyDAO migrationStrategyDao, Restarter restarter) {
     this.repositoryV1UpdateStep = repositoryV1UpdateStep;
     this.migrationStrategyDao = migrationStrategyDao;
+    this.restarter = restarter;
   }
 
   @Override
@@ -121,7 +124,12 @@ class MigrationWizardServlet extends HttpServlet {
 
     ThreadContext.bind(new Subject.Builder(new DefaultSecurityManager()).authenticated(false).buildSubject());
 
-    ScmEventBus.getInstance().post(new RestartEvent(MigrationWizardServlet.class, "wrote migration data"));
+    if (restarter.isSupported()) {
+      restarter.restart(MigrationWizardServlet.class, "wrote migration data");
+    } else {
+      LOG.error("Restarting is not supported on this platform.");
+      LOG.error("Please do a manual restart");
+    }
   }
 
   private List<RepositoryLineEntry> getRepositoryLineEntries() {