| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.flink.statefun.flink.core.di; |
| |
| import java.lang.annotation.Annotation; |
| import java.lang.reflect.Constructor; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.Objects; |
| import java.util.function.Supplier; |
| import javax.annotation.Nullable; |
| import org.apache.flink.annotation.Internal; |
| |
| /** Minimal dependency injection. */ |
| @Internal |
| public class ObjectContainer { |
| |
| private final Map<Key, Supplier<Object>> factories = new HashMap<>(); |
| |
| private final Map<Key, Object> instances = new HashMap<>(); |
| |
| public <T> void add(T singleton) { |
| Class<?> type = singleton.getClass(); |
| factories.put(new Key(type), () -> singleton); |
| } |
| |
| public <T> void add(Class<T> type) { |
| factories.put(new Key(type), () -> createReflectively(type)); |
| } |
| |
| public <T> void add(String label, Class<? super T> type, T singleton) { |
| factories.put(new Key(type, label), () -> singleton); |
| } |
| |
| public <T> void add(String label, Class<? super T> type, Class<?> actual) { |
| factories.put(new Key(type, label), () -> createReflectively(actual)); |
| } |
| |
| public <T, ET> void addAlias( |
| String newLabel, |
| Class<? super T> newType, |
| String existingLabel, |
| Class<? super ET> existingType) { |
| factories.put(new Key(newType, newLabel), () -> get(existingType, existingLabel)); |
| } |
| |
| public <T> void add(String label, Lazy<T> lazyValue) { |
| factories.put(new Key(Lazy.class, label), () -> lazyValue.withContainer(this)); |
| } |
| |
| public <T> T get(Class<T> type) { |
| return get(type, null); |
| } |
| |
| public <T> T get(Class<T> type, String label) { |
| Key key = new Key(type, label); |
| return getOrCreateInstance(key); |
| } |
| |
| @SuppressWarnings("unchecked") |
| private <T> T getOrCreateInstance(Key key) { |
| @Nullable Object instance = instances.get(key); |
| if (instance == null) { |
| instances.put(key, instance = create(key)); |
| } |
| return (T) instance; |
| } |
| |
| private Object create(Key key) { |
| Supplier<Object> factory = factories.get(key); |
| if (factory == null) { |
| throw new IllegalArgumentException("was not able to find a factory for " + key); |
| } |
| return factory.get(); |
| } |
| |
| private Object createReflectively(Class<?> type) { |
| Constructor<?> constructor = findConstructorForInjection(type); |
| Class<?>[] dependencies = constructor.getParameterTypes(); |
| Annotation[][] annotations = constructor.getParameterAnnotations(); |
| Object[] resolvedDependencies = new Object[dependencies.length]; |
| int i = 0; |
| for (Class<?> dependency : dependencies) { |
| @Nullable String label = findLabel(annotations[i]); |
| Key key = new Key(dependency, label); |
| resolvedDependencies[i] = getOrCreateInstance(key); |
| i++; |
| } |
| try { |
| constructor.setAccessible(true); |
| return constructor.newInstance(resolvedDependencies); |
| } catch (Throwable e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| @Nullable |
| private static String findLabel(Annotation[] annotations) { |
| for (Annotation annotation : annotations) { |
| if (annotation.annotationType() == Label.class) { |
| return ((Label) annotation).value(); |
| } |
| } |
| return null; |
| } |
| |
| private static Constructor<?> findConstructorForInjection(Class<?> type) { |
| Constructor<?>[] constructors = type.getDeclaredConstructors(); |
| Constructor<?> defaultCont = null; |
| for (Constructor<?> constructor : constructors) { |
| Annotation annotation = constructor.getAnnotation(Inject.class); |
| if (annotation != null) { |
| return constructor; |
| } |
| if (constructor.getParameterCount() == 0) { |
| defaultCont = constructor; |
| } |
| } |
| if (defaultCont != null) { |
| return defaultCont; |
| } |
| throw new RuntimeException("not injectable type " + type); |
| } |
| |
| private static final class Key { |
| final Class<?> type; |
| |
| @Nullable final String label; |
| |
| Key(Class<?> type, @Nullable String label) { |
| this.type = type; |
| this.label = label; |
| } |
| |
| Key(Class<?> type) { |
| this(type, null); |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| Key key = (Key) o; |
| return Objects.equals(type, key.type) && Objects.equals(label, key.label); |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(type, label); |
| } |
| |
| @Override |
| public String toString() { |
| return "Key{" + "type=" + type + ", label='" + label + '\'' + '}'; |
| } |
| } |
| } |