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/*
* ============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;
import org.onap.policy.common.endpoints.event.comm.bus.internal.BusTopicParams;
/**
* 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);
/**
* Determines if this topic is 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(BusTopicParams param) {
return this.build(param.getServers(), param.getTopic(), param.isManaged());
}
/**
* {@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() + " ]";
}
}
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