Adding NOOP sources support

In addition, Noop* classes have been refactored to
increase code reuse and clean some checkstyle issues.
Additional Junits have been added for existing functionality.

Change-Id: I072f9ff2f415630ac82eca949a8360249f73da86
Issue-ID: POLICY-1397
Signed-off-by: Jorge Hernandez <jorge.hernandez-herrero@att.com>

1 files changed, 197 insertions, 0 deletions

diff --git a/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/bus/TopicBaseHashedFactory.java b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/bus/TopicBaseHashedFactory.java
new file mode 100644
index 00000000..f958bd01
--- /dev/null
+++ b/policy-endpoints/src/main/java/org/onap/policy/common/endpoints/event/comm/bus/TopicBaseHashedFactory.java
@@ -0,0 +1,197 @@
+/*
+ * ============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.endpoints.event.comm.bus;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Properties;
+import org.onap.policy.common.endpoints.event.comm.Topic;
+
+/**
+ * Topic Factory implementation that indexes T instances in a hash table.
+ */
+public abstract class TopicBaseHashedFactory<T extends Topic> implements TopicBaseFactory<T> {
+
+    protected static final String MISSING_TOPIC_MESSAGE = "A topic must be provided";
+    protected static final String MISSING_SERVERS_MESSAGE = "Servers must be provided";
+
+    /**
+     * endpoints.
+     */
+    protected final HashMap<String, T> endpoints = new HashMap<>();
+
+    /**
+     * get the topic names.
+     *
+     * @param properties properties.
+     * @return list of topic names.
+     */
+    protected abstract List<String> getTopicNames(Properties properties);
+
+    /**
+     * get the servers that this topic uses.
+     *
+     * @param topicName name.
+     * @param properties properties.
+     * @return list of servers.
+     */
+    protected abstract List<String> getServers(String topicName, Properties properties);
+
+    /**
+     * is this topic managed?
+     *
+     * @param topicName name.
+     * @param properties properties.
+     * @return if managed.
+     */
+    protected abstract boolean isManaged(String topicName, Properties properties);
+
+    /**
+     * construct an instance of an endpoint.
+     *
+     * @param servers servers,
+     * @param topic topic.
+     * @return an instance of T.
+     */
+    protected abstract T build(List<String> servers, String topic);
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public List<T> build(Properties properties) {
+        List<String> topicNames = getTopicNames(properties);
+        if (topicNames == null || topicNames.isEmpty()) {
+            return Collections.emptyList();
+        }
+
+        List<T> newEndpoints = new ArrayList<>();
+        synchronized (this) {
+            for (String name : topicNames) {
+                if (this.endpoints.containsKey(name)) {
+                    newEndpoints.add(this.endpoints.get(name));
+                    continue;
+                }
+
+                newEndpoints.add(this.build(getServers(name, properties), name, isManaged(name, properties)));
+            }
+        }
+        return newEndpoints;
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public T build(List<String> servers, String topic, boolean managed) {
+        if (servers == null || servers.isEmpty()) {
+            throw new IllegalArgumentException(MISSING_SERVERS_MESSAGE);
+        }
+
+        if (topic == null || topic.isEmpty()) {
+            throw new IllegalArgumentException(MISSING_TOPIC_MESSAGE);
+        }
+
+        synchronized (this) {
+            if (this.endpoints.containsKey(topic)) {
+                return this.endpoints.get(topic);
+            }
+
+            T endpoint = build(servers, topic);
+            if (managed) {
+                this.endpoints.put(topic, endpoint);
+            }
+
+            return endpoint;
+        }
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public void destroy(String topic) {
+        if (topic == null || topic.isEmpty()) {
+            throw new IllegalArgumentException(MISSING_TOPIC_MESSAGE);
+        }
+
+        T endpoint;
+        synchronized (this) {
+            if (!this.endpoints.containsKey(topic)) {
+                return;
+            }
+
+            endpoint = this.endpoints.remove(topic);
+        }
+        endpoint.shutdown();
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public void destroy() {
+        final List<T> snapshotEndpoints = this.inventory();
+        for (final T snapshot : snapshotEndpoints) {
+            snapshot.shutdown();
+        }
+
+        synchronized (this) {
+            this.endpoints.clear();
+        }
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public T get(String topic) {
+        if (topic == null || topic.isEmpty()) {
+            throw new IllegalArgumentException(MISSING_TOPIC_MESSAGE);
+        }
+
+        synchronized (this) {
+            if (this.endpoints.containsKey(topic)) {
+                return this.endpoints.get(topic);
+            } else {
+                throw new IllegalStateException(topic + " not found");
+            }
+        }
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public List<T> inventory() {
+        return new ArrayList<>(this.endpoints.values());
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public String toString() {
+        return "TopicBaseHashedFactory[ " + super.toString() + " ]";
+    }
+}