Merge pull request #4 from flipkart-incubator/fix-data-adapter

Support for subclassed data adapters

pom.xml

@@ -66,7 +66,7 @@
     </build>
 
     <properties>
-        <revision>0.0.1</revision>
+        <revision>0.0.2</revision>
         <guava.version>19.0</guava.version>
         <guice.version>4.2.3</guice.version>
     </properties>

tef-impl/src/main/java/flipkart/tef/exceptions/UnableToResolveDataFromAdapterRuntimeException.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright [2021] [The Original Author]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package flipkart.tef.exceptions;
+
+import flipkart.tef.bizlogics.DataAdapterBizlogic;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * This exception is thrown when Tef cannot figure the return type of data adapter.
+ * Date: 29/03/22
+ * Time: 8:28 AM
+ */
+public class UnableToResolveDataFromAdapterRuntimeException extends RuntimeException {
+
+    private static final String MESSAGE_FORMAT = "Unable to resolve data from Data Adapter Class Hierarchy %s";
+
+    public UnableToResolveDataFromAdapterRuntimeException(List<Class<? extends DataAdapterBizlogic<?>>> classHierarchy) {
+        super(String.format(MESSAGE_FORMAT,
+                classHierarchy.stream().map(Class::getSimpleName)
+                        .collect(Collectors.joining(" -> "))
+                )
+        );
+    }
+}

tef-impl/src/main/java/flipkart/tef/execution/FlowBuilder.java

@@ -28,13 +28,12 @@
 import flipkart.tef.bizlogics.DataAdapterKey;
 import flipkart.tef.bizlogics.IBizlogic;
 import flipkart.tef.bizlogics.IDataBizlogic;
-import flipkart.tef.bizlogics.TefContext;
 import flipkart.tef.capability.AdapterConflictRuntimeException;
+import flipkart.tef.exceptions.UnableToResolveDataFromAdapterRuntimeException;
 import flipkart.tef.flow.SimpleFlow;
 import sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl;
 
 import java.lang.reflect.Field;
-import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -226,30 +225,15 @@ private void populateDataAdapterMap(Class<? extends IBizlogic> bizlogic) {
 
                 Class<?> returnType = null;
 
-                try {
-                    /**
-                     * Using Sun implementation to get generic parameter type. Other considered options were
-                     * 1. Have an interface return the class type - This would require us to instantiate the class
-                     * 2. Have a Type Parameter via Guava - This would require us to instantiate the class
-                     * 3. Get the return type of a known interface method ( `adapt` ) . That is present as fallback for
-                     *      cases where DataAdapterBizlogic is not parameterized.
-                     * 4. Using sun's implementation to get the type param.
-                     */
-                    if (dataAdapterBizLogic.getGenericSuperclass() instanceof ParameterizedTypeImpl) {
-                        ParameterizedTypeImpl genericSuperClass = (ParameterizedTypeImpl) dataAdapterBizLogic.getGenericSuperclass();
-                        if (genericSuperClass.getActualTypeArguments()[0] instanceof Class) {
-                            returnType = (Class<?>) genericSuperClass.getActualTypeArguments()[0];
-                        } else if (genericSuperClass.getActualTypeArguments()[0] instanceof ParameterizedTypeImpl) {
-                            // The type itself is parameterized
-                            returnType = ((ParameterizedTypeImpl) genericSuperClass.getActualTypeArguments()[0]).getRawType();
-                        }
-                    }
-                } finally {
-                    if (returnType == null) {
-                        Method adaptMethod = bizlogic.getMethod("adapt", TefContext.class);
-                        returnType = adaptMethod.getReturnType();
-                    }
-                }
+                /*
+                 * Using Sun implementation to get generic parameter type. Other considered options were
+                 * 1. Have an interface return the class type - This would require us to instantiate the class
+                 * 2. Have a Type Parameter via Guava - This would require us to instantiate the class
+                 * 3. Get the return type of known interface method ( `adapt` ) - this will not work for cases when
+                 *          adapt method is overridden to provide custom context as inputs
+                 * 4. Using sun's implementation to get the type param. - Using this approach
+                 */
+                returnType = getReturnTypeFromBizlogicUsingSunApi(dataAdapterBizLogic, new ArrayList<>());
 
                 DataAdapterKey<?> key = new DataAdapterKey<>(
                         DataAdapterBizlogic.getEmittedDataName(dataAdapterBizLogic), returnType);
@@ -260,11 +244,35 @@ private void populateDataAdapterMap(Class<? extends IBizlogic> bizlogic) {
                     throw new AdapterConflictRuntimeException(returnType, bizlogic, dataAdapterMap.get(key));
                 }
             }
-        } catch (NoSuchMethodException e) {
+        } catch (AdapterConflictRuntimeException|UnableToResolveDataFromAdapterRuntimeException e) {
+            throw e;
+        } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }
 
+    @SuppressWarnings("unchecked")
+    private Class<?> getReturnTypeFromBizlogicUsingSunApi(Class<? extends DataAdapterBizlogic<?>> dataAdapterBizLogic, List<Class<? extends DataAdapterBizlogic<?>>> classHierarchy) {
+        classHierarchy.add(dataAdapterBizLogic);
+        if (dataAdapterBizLogic.getGenericSuperclass() instanceof ParameterizedTypeImpl) {
+            ParameterizedTypeImpl genericSuperClass = (ParameterizedTypeImpl) dataAdapterBizLogic.getGenericSuperclass();
+            if (genericSuperClass.getActualTypeArguments()[0] instanceof Class) {
+                return (Class<?>) genericSuperClass.getActualTypeArguments()[0];
+            } else if (genericSuperClass.getActualTypeArguments()[0] instanceof ParameterizedTypeImpl) {
+                // The type itself is parameterized
+                return ((ParameterizedTypeImpl) genericSuperClass.getActualTypeArguments()[0]).getRawType();
+            }
+        } else {
+            // This could be a case of a data adapter being a subclass of another
+            // data adapter where type parameter is specified on the superclass
+            if(DataAdapterBizlogic.class.isAssignableFrom(dataAdapterBizLogic.getSuperclass())) {
+                return getReturnTypeFromBizlogicUsingSunApi((Class<? extends DataAdapterBizlogic<?>>)dataAdapterBizLogic.getSuperclass(), classHierarchy);
+            }
+        }
+
+        throw new UnableToResolveDataFromAdapterRuntimeException(classHierarchy);
+    }
+
     static class Messages {
         public static final String CYCLIC_GRAPHS_ARE_NOT_SUPPORTED = "Cyclic Graphs are not supported";
         public static final String A_BIZLOGIC_CANNOT_DEPEND_ON_SELF = "A bizlogic cannot depend on Self";

tef-impl/src/test/java/flipkart/tef/execution/FlowBuilderTest.java

@@ -24,6 +24,8 @@
 import flipkart.tef.bizlogics.TefContext;
 import flipkart.tef.capability.AdapterConflictRuntimeException;
 import flipkart.tef.capability.model.MapBaseData;
+import flipkart.tef.exception.TefExecutionException;
+import flipkart.tef.exceptions.UnableToResolveDataFromAdapterRuntimeException;
 import flipkart.tef.flow.SimpleFlow;
 import org.junit.Test;
 
@@ -34,6 +36,7 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
+@SuppressWarnings("unchecked")
 public class FlowBuilderTest {
 
     /**
@@ -331,6 +334,40 @@ public void testComplexDataAdapter() {
         assertTrue(simpleFlow.getBizlogics().contains(DataAdapter3.class));
     }
 
+    @SuppressWarnings("OptionalGetWithoutIsPresent")
+    @Test
+    public void testDataAdapterExtension() {
+        FlowBuilder flowBuilder = new FlowBuilder();
+        flowBuilder.add(SubDataAdapter.class);
+        SimpleFlow simpleFlow = flowBuilder.build();
+        assertEquals(1, simpleFlow.getBizlogics().size());
+        assertTrue(simpleFlow.getBizlogics().contains(SubDataAdapter.class));
+        assertEquals(SimpleData.class, simpleFlow.getDataAdapterMap().keySet().stream().findFirst().get().getResultClass());
+    }
+
+    @SuppressWarnings("OptionalGetWithoutIsPresent")
+    @Test
+    public void testDataAdapterExtension2() {
+        FlowBuilder flowBuilder = new FlowBuilder();
+        flowBuilder.add(SubSubDataAdapter.class);
+        SimpleFlow simpleFlow = flowBuilder.build();
+        assertEquals(1, simpleFlow.getBizlogics().size());
+        assertTrue(simpleFlow.getBizlogics().contains(SubSubDataAdapter.class));
+        assertEquals(SimpleData.class, simpleFlow.getDataAdapterMap().keySet().stream().findFirst().get().getResultClass());
+    }
+
+    @Test
+    public void testDataAdapterExtensionWithoutTypeParam() {
+        FlowBuilder flowBuilder = new FlowBuilder();
+        flowBuilder.add(DataAdapterWithoutTypeParam.class);
+        try {
+            flowBuilder.build();
+            fail("UnableToResolveDataFromAdapterRuntimeException was expected");
+        } catch (UnableToResolveDataFromAdapterRuntimeException e) {
+            // No-op
+        }
+    }
+
 
     class SimpleData extends MapBaseData {
 
@@ -458,4 +495,38 @@ public Map<String, String> adapt(TefContext tefContext) {
         }
     }
 
+    class OtherContext {
+
+    }
+
+    abstract class SuperDataAdapter<T> extends DataAdapterBizlogic<T> {
+
+        @Override
+        public T adapt(TefContext tefContext) {
+            return adapt(tefContext.getAdditionalContext("other", OtherContext.class));
+        }
+
+        public abstract T adapt(OtherContext otherContext);
+
+    }
+
+    abstract class SubDataAdapter extends SuperDataAdapter<SimpleData> {
+
+    }
+
+    class SubSubDataAdapter extends SubDataAdapter {
+        @Override
+        public SimpleData adapt(OtherContext otherContext) {
+            return new SimpleData();
+        }
+    }
+
+    class DataAdapterWithoutTypeParam extends DataAdapterBizlogic {
+
+        @Override
+        public Object adapt(TefContext tefContext) throws TefExecutionException {
+            return null;
+        }
+    }
+
 }

tef-impl/src/test/java/flipkart/tef/execution/FluentCapabilityBuilderTest.java

@@ -194,7 +194,7 @@ public Object getTarget() {
         }
     }
 
-    class DataAdapterBizlogic1 extends DataAdapterBizlogic {
+    class DataAdapterBizlogic1 extends DataAdapterBizlogic<Object> {
 
         @Override
         public Object adapt(TefContext tefContext) {