ensure order & uniqueness of migrations

streampipes-extensions-api/src/main/java/org/apache/streampipes/extensions/api/migration/AdapterMigrator.java

@@ -21,5 +21,13 @@
 import org.apache.streampipes.extensions.api.extractor.IStaticPropertyExtractor;
 import org.apache.streampipes.model.connect.adapter.AdapterDescription;
 
-public interface AdapterMigrator extends ModelMigrator<AdapterDescription, IStaticPropertyExtractor> {
+public abstract class AdapterMigrator implements ModelMigrator<AdapterDescription, IStaticPropertyExtractor> {
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj instanceof ModelMigrator<?, ?>) {
+      return this.config().equals(((ModelMigrator<?, ?>) obj).config());
+    }
+    return false;
+  }
 }

streampipes-extensions-api/src/main/java/org/apache/streampipes/extensions/api/migration/DataSinkMigrator.java

@@ -21,5 +21,13 @@
 import org.apache.streampipes.extensions.api.extractor.IDataSinkParameterExtractor;
 import org.apache.streampipes.model.graph.DataSinkInvocation;
 
-public interface DataSinkMigrator extends ModelMigrator<DataSinkInvocation, IDataSinkParameterExtractor> {
+public abstract class DataSinkMigrator implements ModelMigrator<DataSinkInvocation, IDataSinkParameterExtractor> {
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj instanceof ModelMigrator<?, ?>) {
+      return this.config().equals(((ModelMigrator<?, ?>) obj).config());
+    }
+    return false;
+  }
 }

streampipes-extensions-api/src/main/java/org/apache/streampipes/extensions/api/migration/ModelMigrator.java

@@ -22,17 +22,30 @@
 import org.apache.streampipes.model.base.NamedStreamPipesEntity;
 import org.apache.streampipes.model.migration.ModelMigratorConfig;
 
-public interface ModelMigrator<T extends NamedStreamPipesEntity, ExT extends IParameterExtractor<?>> {
+public interface ModelMigrator<
+        T extends NamedStreamPipesEntity,
+        ExT extends IParameterExtractor<?>
+        > extends Comparable<Object> {
 
   ModelMigratorConfig config();
 
   /**
    * Defines the migration to be performed.
-   * @param element Entity to be transformed.
+   *
+   * @param element   Entity to be transformed.
    * @param extractor Extractor that allows to handle static properties.
    * @return Result of the migration that describes both outcomes: successful and failed migrations
    * @throws RuntimeException in case any unexpected error occurs
    */
   MigrationResult<T> migrate(T element, ExT extractor) throws RuntimeException;
 
+  @Override
+  default int compareTo(Object o) {
+    if (!(o instanceof ModelMigrator<?, ?>)) {
+      throw new ClassCastException("Given object is not an instance of `ModelMigrator` - "
+              + "only instances of `ModelMigrator` can be compared.");
+    } else {
+      return config().compareTo(((ModelMigrator<?, ?>) o).config());
+    }
+  }
 }

streampipes-extensions-management/src/main/java/org/apache/streampipes/extensions/management/model/SpServiceDefinition.java

@@ -27,6 +27,7 @@
 import org.apache.streampipes.model.extensions.configuration.ConfigItem;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
 
@@ -190,7 +191,19 @@ public void addRuntimeProvider(IStreamPipesRuntimeProvider runtimeProvider) {
     return this.migrators;
   }
 
+  /**
+   * Add a list of migrations to the service definition.
+   * This inherently checks for duplicates and sorts the migrations as such that
+   * migrations affecting lower versions always come first.
+   *
+   * @param migrators migrators to add
+   */
   public void addMigrators(List<ModelMigrator<?, ?>> migrators) {
-    this.migrators.addAll(migrators);
+    for (var migratorToAdd : migrators) {
+      if (!this.migrators.contains(migratorToAdd)) {
+        this.migrators.add(migratorToAdd);
+      }
+    }
+    Collections.sort(this.migrators);
   }
 }

streampipes-model/src/main/java/org/apache/streampipes/model/migration/ModelMigratorConfig.java

@@ -29,5 +29,29 @@
  * @param toVersion   Target version that the migration aims to achieve
  */
 public record ModelMigratorConfig(String targetAppId, SpServiceTagPrefix modelType,
-                                  Integer fromVersion, Integer toVersion) {
+                                  int fromVersion, int toVersion) implements Comparable<Object>{
+
+
+  @Override
+  public int compareTo(Object o) {
+
+    if (o == null) {
+      throw new NullPointerException();
+    }
+
+    if (!(o instanceof ModelMigratorConfig)){
+      throw new ClassCastException("Given object is not an instance of `ModelMigratorConfig` - "
+              + "only instances of `ModelMigratorConfig` can be compared.");
+    }
+
+    if (targetAppId.equals(((ModelMigratorConfig) o).targetAppId())) {
+
+      if (fromVersion != ((ModelMigratorConfig) o).fromVersion()) {
+        return this.toVersion() - ((ModelMigratorConfig) o).toVersion();
+      }
+      return this.fromVersion() - ((ModelMigratorConfig) o).fromVersion();
+    }
+
+    return 0;
+  }
 }