--- /dev/null
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a simple object registry, similar in spirit to JNDI, but suitable for use in a
+ * stand-alone JVM.
+ */
+public class Registry {
+ private static final Logger logger = LoggerFactory.getLogger(Registry.class);
+
+ private static volatile Registry instance = new Registry();
+
+ /**
+ * Registry map.
+ */
+ private Map<String, Object> name2object = new ConcurrentHashMap<>();
+
+ /**
+ * Constructs the object.
+ */
+ private Registry() {
+ super();
+ }
+
+ /**
+ * Registers an object.
+ *
+ * @param name name by which the object is known
+ * @param object object to be registered
+ * @throws IllegalStateException if an object is already registered for that name
+ * @throws IllegalArgumentException if either argument is null
+ */
+ public static void register(String name, Object object) {
+ if (name == null) {
+ throw new IllegalArgumentException("attempt to register: " + name);
+ }
+
+ if (object == null) {
+ throw new IllegalArgumentException("attempt to register null object for " + name);
+ }
+
+ instance.name2object.compute(name, (key, oldval) -> {
+
+ if (oldval != null) {
+ throw new IllegalStateException("already registered: " + name);
+ }
+
+ return object;
+ });
+ }
+
+ /**
+ * Registers an object, replacing any previously existing binding.
+ *
+ * @param name name by which the object is known
+ * @param object object to be registered
+ * @throws IllegalArgumentException if either argument is null
+ */
+ public static void registerOrReplace(String name, Object object) {
+ if (name == null) {
+ throw new IllegalArgumentException("attempt to register: " + name);
+ }
+
+ if (object == null) {
+ throw new IllegalArgumentException("attempt to register null object for " + name);
+ }
+
+ instance.name2object.compute(name, (key, oldval) -> {
+
+ if (oldval != null) {
+ logger.warn("replacing previously registered: {}", name);
+ }
+
+ return object;
+ });
+ }
+
+ /**
+ * Unregisters an object.
+ *
+ * @param name name by which the object is known
+ * @return {@code true} if the object was unregistered, {@code false} if it did not
+ * exist
+ */
+ public static boolean unregister(String name) {
+ return (instance.name2object.remove(name) != null);
+ }
+
+ /**
+ * Gets the object by the given name.
+ *
+ * @param name name of the object to get
+ * @param clazz object's class
+ * @return the object
+ * @throws IllegalArgumentException if no object is registered by the given name
+ */
+ public static <T> T get(String name, Class<T> clazz) {
+ Object obj = instance.name2object.get(name);
+ if (obj == null) {
+ throw new IllegalArgumentException("not registered: " + name);
+ }
+
+ return clazz.cast(obj);
+ }
+
+ /**
+ * Gets the object by the given name, providing a default value if the name is not
+ * registered.
+ *
+ * @param name name of the object to get
+ * @param clazz object's class
+ * @param defaultVal the default value to return, if the object does not exist
+ * @return the object, if it exists, the default value, otherwise
+ */
+ public static <T> T getOrDefault(String name, Class<T> clazz, T defaultVal) {
+ Object obj = instance.name2object.get(name);
+ return (obj != null ? clazz.cast(obj) : defaultVal);
+ }
+
+ /**
+ * Creates a new registry instance. This is typically only used by junit tests, as it
+ * discards any previous registry entries.
+ */
+ public static void newRegistry() {
+ instance = new Registry();
+ }
+}
--- /dev/null
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.Test;
+
+public class RegistryTest {
+ private static final String UNKNOWN = "unknown";
+ private static final String NAME_STR = "name-string";
+ private static final String NAME_OBJ = "name-object";
+ private static final String NAME_INT = "name-integer";
+
+ private static final String DATA_STR = "data-1";
+ private static final Object DATA_OBJ = new Object();
+ private static final Integer DATA_INT = 5;
+
+ /**
+ * Set up.
+ */
+ @Before
+ public void setUp() {
+ Registry.newRegistry();
+
+ Registry.register(NAME_STR, DATA_STR);
+ Registry.register(NAME_OBJ, DATA_OBJ);
+ Registry.register(NAME_INT, DATA_INT);
+ }
+
+ /**
+ * Ensure the registry is left empty when done.
+ */
+ @AfterClass
+ public static void tearDownAfterClass() {
+ Registry.newRegistry();
+ }
+
+ /**
+ * Sunny day scenario is tested by other tests, so we focus on exceptions here.
+ */
+ @Test
+ public void testRegister_Ex() {
+ assertThatIllegalStateException().isThrownBy(() -> Registry.register(NAME_STR, DATA_STR));
+
+ assertThatIllegalArgumentException().isThrownBy(() -> Registry.register(null, DATA_STR));
+ assertThatIllegalArgumentException().isThrownBy(() -> Registry.register(UNKNOWN, null));
+ }
+
+ @Test
+ public void testRegisterOrReplace() {
+ // should be able to replace
+ Registry.registerOrReplace(NAME_STR, DATA_STR);
+ Registry.registerOrReplace(NAME_STR, DATA_STR);
+ assertSame(DATA_STR, Registry.get(NAME_STR, String.class));
+
+ // should also be able to add
+ Registry.registerOrReplace(UNKNOWN, DATA_INT);
+ assertSame(DATA_INT, Registry.get(UNKNOWN, Integer.class));
+
+ // check exception cases
+ assertThatIllegalArgumentException().isThrownBy(() -> Registry.registerOrReplace(null, DATA_STR));
+ assertThatIllegalArgumentException().isThrownBy(() -> Registry.registerOrReplace(UNKNOWN, null));
+ }
+
+ @Test
+ public void testUnregister() {
+ assertTrue(Registry.unregister(NAME_STR));
+
+ assertEquals(null, Registry.getOrDefault(NAME_STR, String.class, null));
+
+ assertFalse(Registry.unregister(NAME_STR));
+ }
+
+ @Test
+ public void testGet() {
+ assertSame(DATA_STR, Registry.get(NAME_STR, String.class));
+ assertSame(DATA_OBJ, Registry.get(NAME_OBJ, Object.class));
+ assertSame(DATA_INT, Registry.get(NAME_INT, Integer.class));
+
+ // does not exist
+ assertThatIllegalArgumentException().isThrownBy(() -> Registry.get(UNKNOWN, Object.class));
+
+ // wrong type
+ assertThatThrownBy(() -> Registry.get(NAME_INT, String.class)).isInstanceOf(ClassCastException.class);
+ }
+
+ @Test
+ public void testGetOrDefault() {
+ assertSame(DATA_STR, Registry.getOrDefault(NAME_STR, String.class, null));
+ assertSame(DATA_OBJ, Registry.getOrDefault(NAME_OBJ, Object.class, "xyz"));
+ assertSame(DATA_INT, Registry.getOrDefault(NAME_INT, Integer.class, 10));
+
+ assertEquals(null, Registry.getOrDefault(UNKNOWN, String.class, null));
+ assertEquals("abc", Registry.getOrDefault(UNKNOWN, String.class, "abc"));
+ assertEquals(Integer.valueOf(11), Registry.getOrDefault(UNKNOWN, Integer.class, 11));
+ }
+
+ @Test
+ public void testNewRegistry() {
+ assertSame(DATA_STR, Registry.get(NAME_STR, String.class));
+
+ Registry.newRegistry();
+
+ // should not exist
+ assertEquals(null, Registry.getOrDefault(NAME_STR, String.class, null));
+
+ // should be able to register it again now
+ Registry.register(NAME_STR, DATA_STR);
+ assertSame(DATA_STR, Registry.get(NAME_STR, String.class));
+ }
+
+}
Code Review / policy / common.git / commitdiff