Merged in feature/migration (pull request #249)

Feature migration

scm-webapp/src/main/java/sonia/scm/ScmContextListener.java

@@ -37,6 +37,7 @@ import com.google.common.base.Throwables;
 import com.google.common.collect.Lists;
 import com.google.inject.Injector;
 import com.google.inject.Module;
+import com.google.inject.assistedinject.Assisted;
 import org.apache.shiro.guice.web.ShiroWebModule;
 import org.jboss.resteasy.plugins.guice.GuiceResteasyBootstrapServletContextListener;
 import org.slf4j.Logger;
@@ -55,6 +56,7 @@ import sonia.scm.upgrade.UpgradeManager;
 import sonia.scm.user.UserManager;
 import sonia.scm.util.IOUtil;
 
+import javax.inject.Inject;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletContextEvent;
 import java.util.Collections;
@@ -77,9 +79,12 @@ public class ScmContextListener extends GuiceResteasyBootstrapServletContextList
   private final Set<PluginWrapper> plugins;
   private Injector injector;
   
-  //~--- constructors ---------------------------------------------------------
-  
-  public ScmContextListener(ClassLoader parent, Set<PluginWrapper> plugins)
+  public interface Factory {
+    ScmContextListener create(ClassLoader parent, Set<PluginWrapper> plugins);
+  }
+
+  @Inject
+  public ScmContextListener(@Assisted ClassLoader parent, @Assisted Set<PluginWrapper> plugins)
   {
     this.parent = parent;
     this.plugins = plugins;
@@ -127,9 +132,6 @@ public class ScmContextListener extends GuiceResteasyBootstrapServletContextList
     List<Module> moduleList = Lists.newArrayList();
 
     moduleList.add(new ResteasyModule());
-    moduleList.add(new ScmInitializerModule());
-    moduleList.add(new ScmEventBusModule());
-    moduleList.add(new EagerSingletonModule());
     moduleList.add(ShiroWebModule.guiceFilterModule());
     moduleList.add(new WebElementModule(pluginLoader));
     moduleList.add(new ScmServletModule(context, pluginLoader, overrides));

scm-webapp/src/main/java/sonia/scm/ScmServletModule.java

@@ -212,12 +212,7 @@ public class ScmServletModule extends ServletModule
   {
     install(ThrowingProviderBinder.forModule(this));
 
-    SCMContextProvider context = SCMContext.getContext();
-
-    bind(SCMContextProvider.class).toInstance(context);
-
     ScmConfiguration config = getScmConfiguration();
-    CipherUtil cu = CipherUtil.getInstance();
 
     bind(NamespaceStrategy.class).toProvider(NamespaceStrategyProvider.class);
 
@@ -234,21 +229,11 @@ public class ScmServletModule extends ServletModule
     bind(ScmEventBus.class).toInstance(ScmEventBus.getInstance());
 
     // bind core
-    bind(ConfigurationStoreFactory.class, JAXBConfigurationStoreFactory.class);
-    bind(ConfigurationEntryStoreFactory.class, JAXBConfigurationEntryStoreFactory.class);
-    bind(DataStoreFactory.class, JAXBDataStoreFactory.class);
-    bind(BlobStoreFactory.class, FileBlobStoreFactory.class);
     bind(ScmConfiguration.class).toInstance(config);
-    bind(PluginLoader.class).toInstance(pluginLoader);
     bind(PluginManager.class, DefaultPluginManager.class);
 
     // bind scheduler
     bind(Scheduler.class).to(QuartzScheduler.class);
-    
-    // note CipherUtil uses an other generator
-    bind(KeyGenerator.class).to(DefaultKeyGenerator.class);
-    bind(CipherHandler.class).toInstance(cu.getCipherHandler());
-    bind(FileSystem.class, DefaultFileSystem.class);
 
     // bind health check stuff
     bind(HealthCheckContextListener.class);
@@ -327,7 +312,6 @@ public class ScmServletModule extends ServletModule
     bind(ObjectMapper.class).toProvider(ObjectMapperProvider.class);
 
     // bind events
-    // bind(LastModifiedUpdateListener.class);
 
     bind(AccessTokenCookieIssuer.class).to(DefaultAccessTokenCookieIssuer.class);
     bind(PushStateDispatcher.class).toProvider(PushStateDispatcherProvider.class);

scm-webapp/src/main/java/sonia/scm/boot/BootstrapContextListener.java

@@ -1,9 +1,9 @@
 /**
  * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
- *
+ * <p>
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
- *
+ * <p>
  * 1. Redistributions of source code must retain the above copyright notice,
  * this list of conditions and the following disclaimer. 2. Redistributions in
  * binary form must reproduce the above copyright notice, this list of
@@ -11,7 +11,7 @@
  * materials provided with the distribution. 3. Neither the name of SCM-Manager;
  * nor the names of its contributors may be used to endorse or promote products
  * derived from this software without specific prior written permission.
- *
+ * <p>
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
@@ -22,67 +22,65 @@
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
+ * <p>
  * http://bitbucket.org/sdorra/scm-manager
- *
  */
 
 
-
 package sonia.scm.boot;
 
-//~--- non-JDK imports --------------------------------------------------------
-
 import com.google.common.base.Charsets;
 import com.google.common.collect.ImmutableList;
 import com.google.common.io.Files;
-
+import com.google.inject.AbstractModule;
+import com.google.inject.Guice;
+import com.google.inject.Injector;
+import com.google.inject.Module;
+import com.google.inject.assistedinject.FactoryModuleBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
+import sonia.scm.EagerSingletonModule;
 import sonia.scm.SCMContext;
 import sonia.scm.ScmContextListener;
+import sonia.scm.ScmEventBusModule;
+import sonia.scm.ScmInitializerModule;
 import sonia.scm.Stage;
 import sonia.scm.event.ScmEventBus;
+import sonia.scm.plugin.DefaultPluginLoader;
 import sonia.scm.plugin.Plugin;
 import sonia.scm.plugin.PluginException;
 import sonia.scm.plugin.PluginLoadException;
+import sonia.scm.plugin.PluginLoader;
 import sonia.scm.plugin.PluginWrapper;
 import sonia.scm.plugin.PluginsInternal;
 import sonia.scm.plugin.SmpArchive;
+import sonia.scm.update.UpdateEngine;
 import sonia.scm.util.ClassLoaders;
 import sonia.scm.util.IOUtil;
 
-//~--- JDK imports ------------------------------------------------------------
-
-import java.io.Closeable;
-import java.io.File;
-import java.io.IOException;
-
-import java.net.MalformedURLException;
-import java.net.URL;
-
-import java.util.Iterator;
-import java.util.List;
-import java.util.Set;
-
 import javax.servlet.ServletContext;
 import javax.servlet.ServletContextEvent;
 import javax.servlet.ServletContextListener;
-
 import javax.xml.bind.DataBindingException;
 import javax.xml.bind.JAXB;
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
+import java.io.Closeable;
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
 
 /**
  *
  * @author Sebastian Sdorra
  */
-public class BootstrapContextListener implements ServletContextListener
-{
+public class BootstrapContextListener implements ServletContextListener {
 
   /** Field description */
   private static final String DIRECTORY_PLUGINS = "plugins";
@@ -109,22 +107,16 @@ public class BootstrapContextListener implements ServletContextListener
    * @param sce
    */
   @Override
-  public void contextDestroyed(ServletContextEvent sce)
-  {
+  public void contextDestroyed(ServletContextEvent sce) {
     contextListener.contextDestroyed(sce);
 
-    for (PluginWrapper plugin : contextListener.getPlugins())
-    {
+    for (PluginWrapper plugin : contextListener.getPlugins()) {
       ClassLoader pcl = plugin.getClassLoader();
 
-      if (pcl instanceof Closeable)
-      {
-        try
-        {
+      if (pcl instanceof Closeable) {
+        try {
           ((Closeable) pcl).close();
-        }
-        catch (IOException ex)
-        {
+        } catch (IOException ex) {
           logger.warn("could not close plugin classloader", ex);
         }
       }
@@ -141,43 +133,68 @@ public class BootstrapContextListener implements ServletContextListener
    * @param sce
    */
   @Override
-  public void contextInitialized(ServletContextEvent sce)
-  {
+  public void contextInitialized(ServletContextEvent sce) {
     context = sce.getServletContext();
 
     File pluginDirectory = getPluginDirectory();
 
-    try
-    {
+    createContextListener(pluginDirectory);
+
+    contextListener.contextInitialized(sce);
+
+    // register for restart events
+    if (!registered && (SCMContext.getContext().getStage() == Stage.DEVELOPMENT)) {
+      logger.info("register for restart events");
+      ScmEventBus.getInstance().register(this);
+      registered = true;
+    }
+  }
+
+  private void createContextListener(File pluginDirectory) {
+    try {
       if (!isCorePluginExtractionDisabled()) {
         extractCorePlugins(context, pluginDirectory);
       } else {
         logger.info("core plugin extraction is disabled");
       }
 
-      ClassLoader cl =
-        ClassLoaders.getContextClassLoader(BootstrapContextListener.class);
+      ClassLoader cl = ClassLoaders.getContextClassLoader(BootstrapContextListener.class);
 
-      Set<PluginWrapper> plugins = PluginsInternal.collectPlugins(cl,
-                                     pluginDirectory.toPath());
+      Set<PluginWrapper> plugins = PluginsInternal.collectPlugins(cl, pluginDirectory.toPath());
 
-      contextListener = new ScmContextListener(cl, plugins);
-    }
-    catch (IOException ex)
-    {
+      PluginLoader pluginLoader = new DefaultPluginLoader(context, cl, plugins);
+
+      Injector bootstrapInjector = createBootstrapInjector(pluginLoader);
+
+      processUpdates(pluginLoader, bootstrapInjector);
+
+      contextListener = bootstrapInjector.getInstance(ScmContextListener.Factory.class).create(cl, plugins);
+    } catch (IOException ex) {
       throw new PluginLoadException("could not load plugins", ex);
     }
+  }
 
-    contextListener.contextInitialized(sce);
-    
-        // register for restart events
-    if (!registered
-      && (SCMContext.getContext().getStage() == Stage.DEVELOPMENT))
-    {
-      logger.info("register for restart events");
-      ScmEventBus.getInstance().register(this);
-      registered = true;
-    }
+  private Injector createBootstrapInjector(PluginLoader pluginLoader) {
+    Module scmContextListenerModule = new ScmContextListenerModule();
+    BootstrapModule bootstrapModule = new BootstrapModule(pluginLoader);
+    ScmInitializerModule scmInitializerModule = new ScmInitializerModule();
+    EagerSingletonModule eagerSingletonModule = new EagerSingletonModule();
+    ScmEventBusModule scmEventBusModule = new ScmEventBusModule();
+
+    return Guice.createInjector(
+      bootstrapModule,
+      scmContextListenerModule,
+      scmEventBusModule,
+      scmInitializerModule,
+      eagerSingletonModule
+    );
+  }
+
+  private void processUpdates(PluginLoader pluginLoader, Injector bootstrapInjector) {
+    Injector updateInjector = bootstrapInjector.createChildInjector(new UpdateStepModule(pluginLoader));
+
+    UpdateEngine updateEngine = updateInjector.getInstance(UpdateEngine.class);
+    updateEngine.update();
   }
 
   private boolean isCorePluginExtractionDisabled() {
@@ -195,41 +212,32 @@ public class BootstrapContextListener implements ServletContextListener
    * @throws IOException
    */
   private void extractCorePlugin(ServletContext context, File pluginDirectory,
-    PluginIndexEntry entry)
-    throws IOException
-  {
+                                 PluginIndexEntry entry)
+    throws IOException {
     URL url = context.getResource(PLUGIN_DIRECTORY.concat(entry.getName()));
     SmpArchive archive = SmpArchive.create(url);
     Plugin plugin = archive.getPlugin();
 
     File directory = PluginsInternal.createPluginDirectory(pluginDirectory,
-                       plugin);
+      plugin);
     File checksumFile = PluginsInternal.getChecksumFile(directory);
 
-    if (!directory.exists())
-    {
+    if (!directory.exists()) {
       logger.warn("install plugin {}", plugin.getInformation().getId());
       PluginsInternal.extract(archive, entry.getChecksum(), directory,
         checksumFile, true);
-    }
-    else if (!checksumFile.exists())
-    {
+    } else if (!checksumFile.exists()) {
       logger.warn("plugin directory {} exists without checksum file.",
         directory);
       PluginsInternal.extract(archive, entry.getChecksum(), directory,
         checksumFile, true);
-    }
-    else
-    {
+    } else {
       String checksum = Files.toString(checksumFile, Charsets.UTF_8).trim();
 
-      if (checksum.equals(entry.getChecksum()))
-      {
+      if (checksum.equals(entry.getChecksum())) {
         logger.debug("plugin {} is up to date",
           plugin.getInformation().getId());
-      }
-      else
-      {
+      } else {
         logger.warn("checksum mismatch of pluing {}, start update",
           plugin.getInformation().getId());
         PluginsInternal.extract(archive, entry.getChecksum(), directory,
@@ -247,14 +255,12 @@ public class BootstrapContextListener implements ServletContextListener
    *
    * @throws IOException
    */
-  private void extractCorePlugins(ServletContext context, File pluginDirectory) throws IOException
-  {
+  private void extractCorePlugins(ServletContext context, File pluginDirectory) throws IOException {
     IOUtil.mkdirs(pluginDirectory);
 
     PluginIndex index = readCorePluginIndex(context);
 
-    for (PluginIndexEntry entry : index)
-    {
+    for (PluginIndexEntry entry : index) {
       extractCorePlugin(context, pluginDirectory, entry);
     }
   }
@@ -267,27 +273,20 @@ public class BootstrapContextListener implements ServletContextListener
    *
    * @return
    */
-  private PluginIndex readCorePluginIndex(ServletContext context)
-  {
+  private PluginIndex readCorePluginIndex(ServletContext context) {
     PluginIndex index = null;
 
-    try
-    {
+    try {
       URL indexUrl = context.getResource(PLUGIN_COREINDEX);
 
-      if (indexUrl == null)
-      {
+      if (indexUrl == null) {
         throw new PluginException("no core plugin index found");
       }
 
       index = JAXB.unmarshal(indexUrl, PluginIndex.class);
-    }
-    catch (MalformedURLException ex)
-    {
+    } catch (MalformedURLException ex) {
       throw new PluginException("could not load core plugin index", ex);
-    }
-    catch (DataBindingException ex)
-    {
+    } catch (DataBindingException ex) {
       throw new PluginException("could not unmarshall core plugin index", ex);
     }
 
@@ -302,8 +301,7 @@ public class BootstrapContextListener implements ServletContextListener
    *
    * @return
    */
-  private File getPluginDirectory()
-  {
+  private File getPluginDirectory() {
     File baseDirectory = SCMContext.getContext().getBaseDirectory();
 
     return new File(baseDirectory, DIRECTORY_PLUGINS);
@@ -315,13 +313,12 @@ public class BootstrapContextListener implements ServletContextListener
    * Class description
    *
    *
-   * @version        Enter version here..., 14/07/09
-   * @author         Enter your name here...
+   * @version Enter version here..., 14/07/09
+   * @author Enter your name here...
    */
   @XmlAccessorType(XmlAccessType.FIELD)
   @XmlRootElement(name = "plugin-index")
-  private static class PluginIndex implements Iterable<PluginIndexEntry>
-  {
+  private static class PluginIndex implements Iterable<PluginIndexEntry> {
 
     /**
      * Method description
@@ -330,8 +327,7 @@ public class BootstrapContextListener implements ServletContextListener
      * @return
      */
     @Override
-    public Iterator<PluginIndexEntry> iterator()
-    {
+    public Iterator<PluginIndexEntry> iterator() {
       return getPlugins().iterator();
     }
 
@@ -343,10 +339,8 @@ public class BootstrapContextListener implements ServletContextListener
      *
      * @return
      */
-    public List<PluginIndexEntry> getPlugins()
-    {
-      if (plugins == null)
-      {
+    public List<PluginIndexEntry> getPlugins() {
+      if (plugins == null) {
         plugins = ImmutableList.of();
       }
 
@@ -365,13 +359,12 @@ public class BootstrapContextListener implements ServletContextListener
    * Class description
    *
    *
-   * @version        Enter version here..., 14/07/09
-   * @author         Enter your name here...
+   * @version Enter version here..., 14/07/09
+   * @author Enter your name here...
    */
   @XmlRootElement(name = "plugins")
   @XmlAccessorType(XmlAccessType.FIELD)
-  private static class PluginIndexEntry
-  {
+  private static class PluginIndexEntry {
 
     /**
      * Method description
@@ -379,8 +372,7 @@ public class BootstrapContextListener implements ServletContextListener
      *
      * @return
      */
-    public String getChecksum()
-    {
+    public String getChecksum() {
       return checksum;
     }
 
@@ -390,8 +382,7 @@ public class BootstrapContextListener implements ServletContextListener
      *
      * @return
      */
-    public String getName()
-    {
+    public String getName() {
       return name;
     }
 
@@ -415,4 +406,11 @@ public class BootstrapContextListener implements ServletContextListener
 
   /** Field description */
   private boolean registered = false;
+
+  private static class ScmContextListenerModule extends AbstractModule {
+    @Override
+    protected void configure() {
+      install(new FactoryModuleBuilder().build(ScmContextListener.Factory.class));
+    }
+  }
 }

scm-webapp/src/main/java/sonia/scm/boot/BootstrapModule.java

@@ -0,0 +1,86 @@
+package sonia.scm.boot;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.throwingproviders.ThrowingProviderBinder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import sonia.scm.ClassOverrides;
+import sonia.scm.SCMContext;
+import sonia.scm.SCMContextProvider;
+import sonia.scm.io.DefaultFileSystem;
+import sonia.scm.io.FileSystem;
+import sonia.scm.plugin.PluginLoader;
+import sonia.scm.repository.RepositoryLocationResolver;
+import sonia.scm.repository.xml.PathBasedRepositoryLocationResolver;
+import sonia.scm.security.CipherHandler;
+import sonia.scm.security.CipherUtil;
+import sonia.scm.security.DefaultKeyGenerator;
+import sonia.scm.security.KeyGenerator;
+import sonia.scm.store.BlobStoreFactory;
+import sonia.scm.store.ConfigurationEntryStoreFactory;
+import sonia.scm.store.ConfigurationStoreFactory;
+import sonia.scm.store.DataStoreFactory;
+import sonia.scm.store.FileBlobStoreFactory;
+import sonia.scm.store.JAXBConfigurationEntryStoreFactory;
+import sonia.scm.store.JAXBConfigurationStoreFactory;
+import sonia.scm.store.JAXBDataStoreFactory;
+
+public class BootstrapModule extends AbstractModule {
+
+  private static final Logger LOG = LoggerFactory.getLogger(BootstrapModule.class);
+
+  private final ClassOverrides overrides;
+  private final PluginLoader pluginLoader;
+
+  BootstrapModule(PluginLoader pluginLoader) {
+    this.overrides = ClassOverrides.findOverrides(pluginLoader.getUberClassLoader());
+    this.pluginLoader = pluginLoader;
+  }
+
+  @Override
+  protected void configure() {
+    install(ThrowingProviderBinder.forModule(this));
+
+    SCMContextProvider context = SCMContext.getContext();
+
+    bind(SCMContextProvider.class).toInstance(context);
+
+    bind(KeyGenerator.class).to(DefaultKeyGenerator.class);
+
+    bind(RepositoryLocationResolver.class).to(PathBasedRepositoryLocationResolver.class);
+
+    bind(FileSystem.class, DefaultFileSystem.class);
+
+    // note CipherUtil uses an other generator
+    bind(CipherHandler.class).toInstance(CipherUtil.getInstance().getCipherHandler());
+
+    // bind core
+    bind(ConfigurationStoreFactory.class, JAXBConfigurationStoreFactory.class);
+    bind(ConfigurationEntryStoreFactory.class, JAXBConfigurationEntryStoreFactory.class);
+    bind(DataStoreFactory.class, JAXBDataStoreFactory.class);
+    bind(BlobStoreFactory.class, FileBlobStoreFactory.class);
+    bind(PluginLoader.class).toInstance(pluginLoader);
+  }
+
+  private <T> void bind(Class<T> clazz, Class<? extends T> defaultImplementation) {
+    Class<? extends T> implementation = find(clazz, defaultImplementation);
+    LOG.debug("bind {} to {}", clazz, implementation);
+    bind(clazz).to(implementation);
+  }
+
+  private <T> Class<? extends T> find(Class<T> clazz, Class<? extends T> defaultImplementation) {
+    Class<? extends T> implementation = overrides.getOverride(clazz);
+
+    if (implementation != null) {
+      LOG.info("found override {} for {}", implementation, clazz);
+    } else {
+      implementation = defaultImplementation;
+
+      LOG.trace(
+        "no override available for {}, using default implementation {}",
+        clazz, implementation);
+    }
+
+    return implementation;
+  }
+}

scm-webapp/src/main/java/sonia/scm/boot/UpdateStepModule.java

@@ -0,0 +1,24 @@
+package sonia.scm.boot;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.multibindings.Multibinder;
+import sonia.scm.migration.UpdateStep;
+import sonia.scm.plugin.PluginLoader;
+
+class UpdateStepModule extends AbstractModule {
+
+  private final PluginLoader pluginLoader;
+
+  UpdateStepModule(PluginLoader pluginLoader) {
+    this.pluginLoader = pluginLoader;
+  }
+
+  @Override
+  protected void configure() {
+    Multibinder<UpdateStep> updateStepBinder = Multibinder.newSetBinder(binder(), UpdateStep.class);
+    pluginLoader
+      .getExtensionProcessor()
+      .byExtensionPoint(UpdateStep.class)
+      .forEach(stepClass -> updateStepBinder.addBinding().to(stepClass));
+  }
+}

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

@@ -0,0 +1,86 @@
+package sonia.scm.update;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import sonia.scm.migration.UpdateException;
+import sonia.scm.migration.UpdateStep;
+import sonia.scm.store.ConfigurationEntryStore;
+import sonia.scm.store.ConfigurationEntryStoreFactory;
+
+import javax.inject.Inject;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Set;
+
+import static java.util.stream.Collectors.toList;
+
+public class UpdateEngine {
+
+  public static final Logger LOG = LoggerFactory.getLogger(UpdateEngine.class);
+
+  private static final String STORE_NAME = "executedUpdates";
+
+  private final List<UpdateStep> steps;
+  private final ConfigurationEntryStore<UpdateVersionInfo> store;
+
+  @Inject
+  public UpdateEngine(Set<UpdateStep> steps, ConfigurationEntryStoreFactory storeFactory) {
+    this.steps = sortSteps(steps);
+    this.store = storeFactory.withType(UpdateVersionInfo.class).withName(STORE_NAME).build();
+  }
+
+  private List<UpdateStep> sortSteps(Set<UpdateStep> steps) {
+    LOG.trace("sorting available update steps:");
+    List<UpdateStep> sortedSteps = steps.stream()
+      .sorted(Comparator.comparing(UpdateStep::getTargetVersion).reversed())
+      .collect(toList());
+    sortedSteps.forEach(step -> LOG.trace("{} for version {}", step.getAffectedDataType(), step.getTargetVersion()));
+    return sortedSteps;
+  }
+
+  public void update() {
+    steps
+      .stream()
+      .filter(this::notRunYet)
+      .forEach(this::execute);
+  }
+
+  private void execute(UpdateStep updateStep) {
+    try {
+      LOG.info("running update step for type {} and version {}",
+        updateStep.getAffectedDataType(),
+        updateStep.getTargetVersion()
+      );
+      updateStep.doUpdate();
+    } catch (Exception e) {
+      throw new UpdateException(
+        String.format(
+          "could not execute update for type %s to version %s in class %s",
+          updateStep.getAffectedDataType(),
+          updateStep.getTargetVersion(),
+          updateStep.getClass()),
+        e);
+    }
+    UpdateVersionInfo newVersionInfo = new UpdateVersionInfo(updateStep.getTargetVersion().getParsedVersion());
+    store.put(updateStep.getAffectedDataType(), newVersionInfo);
+  }
+
+  private boolean notRunYet(UpdateStep updateStep) {
+    LOG.trace("checking whether to run update step for type {} and version {}",
+      updateStep.getAffectedDataType(),
+      updateStep.getTargetVersion()
+    );
+    UpdateVersionInfo updateVersionInfo = store.get(updateStep.getAffectedDataType());
+    if (updateVersionInfo == null) {
+      LOG.trace("no updates for type {} run yet; step will be executed", updateStep.getAffectedDataType());
+      return true;
+    }
+    boolean result = updateStep.getTargetVersion().isNewer(updateVersionInfo.getLatestVersion());
+    LOG.trace("latest version for type {}: {}; step will be executed: {}",
+      updateStep.getAffectedDataType(),
+      updateVersionInfo.getLatestVersion(),
+      result
+    );
+    return result;
+  }
+}

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

@@ -0,0 +1,22 @@
+package sonia.scm.update;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlRootElement;
+
+@XmlRootElement(name = "latest-version")
+@XmlAccessorType(XmlAccessType.FIELD)
+public class UpdateVersionInfo {
+  private String latestVersion;
+
+  public UpdateVersionInfo() {
+  }
+
+  public UpdateVersionInfo(String latestVersion) {
+    this.latestVersion = latestVersion;
+  }
+
+  public String getLatestVersion() {
+    return latestVersion;
+  }
+}