Run update steps only if they have not been run before

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

@@ -0,0 +1,53 @@
+package sonia.scm.update;
+
+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 {
+
+  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) {
+    return steps.stream()
+      .sorted(Comparator.comparing(UpdateStep::getTargetVersion).reversed())
+      .collect(toList());
+  }
+
+  public void update() {
+    steps
+      .stream()
+      .filter(this::notRunYet)
+      .forEach(this::execute);
+  }
+
+  private void execute(UpdateStep updateStep) {
+    updateStep.doUpdate();
+    UpdateVersionInfo newVersionInfo = new UpdateVersionInfo(updateStep.getTargetVersion().getParsedVersion());
+    store.put(updateStep.affectedDataType(), newVersionInfo);
+  }
+
+  private boolean notRunYet(UpdateStep updateStep) {
+    UpdateVersionInfo updateVersionInfo = store.get(updateStep.affectedDataType());
+    if (updateVersionInfo == null) {
+      return true;
+    }
+    return updateStep.getTargetVersion().isNewer(updateVersionInfo.getLatestVersion());
+  }
+}