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/*******************************************************************************
* ============LICENSE_START==================================================
* * org.onap.dmaap
* * ===========================================================================
* * Copyright © 2017 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====================================================
* *
* * ECOMP is a trademark and service mark of AT&T Intellectual Property.
* *
******************************************************************************/
package org.onap.dmaap.datarouter.node;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import org.jetbrains.annotations.Nullable;
import org.onap.dmaap.datarouter.node.NodeConfig.ProvHop;
/**
* Given a set of node names and next hops, identify and ignore any cycles and figure out the sequence of next hops to
* get from this node to any other node.
*/
class PathFinder {
private ArrayList<String> errors = new ArrayList<>();
private HashMap<String, String> routes = new HashMap<>();
/**
* Find routes from a specified origin to all of the nodes given a set of specified next hops.
*
* @param origin where we start
* @param nodes where we can go
* @param hops detours along the way
*/
PathFinder(String origin, String[] nodes, NodeConfig.ProvHop[] hops) {
HashSet<String> known = new HashSet<>();
HashMap<String, HashMap<String, Hop>> ht = new HashMap<>();
for (String n : nodes) {
known.add(n);
ht.put(n, new HashMap<>());
}
for (NodeConfig.ProvHop ph : hops) {
Hop hop = getHop(known, ht, ph);
if (hop == null) {
continue;
}
if (ph.getVia().equals(ph.getTo())) {
errors.add(ph + " gives destination as via");
hop.bad = true;
}
}
for (String n : known) {
if (n.equals(origin)) {
routes.put(n, "");
}
routes.put(n, plot(origin, n, ht.get(n)) + "/");
}
}
/**
* Get list of errors encountered while finding paths.
*
* @return array of error descriptions
*/
String[] getErrors() {
return (errors.toArray(new String[0]));
}
/**
* Get the route from this node to the specified node.
*
* @param destination node
* @return list of node names separated by and ending with "/"
*/
String getPath(String destination) {
String ret = routes.get(destination);
if (ret == null) {
return ("");
}
return (ret);
}
private String plot(String from, String to, HashMap<String, Hop> info) {
Hop nh = info.get(from);
if (nh == null || nh.bad) {
return (to);
}
if (nh.mark) {
while (!nh.bad) {
nh.bad = true;
errors.add(nh.basis + " is part of a cycle");
nh = info.get(nh.basis.getVia());
}
return (to);
}
nh.mark = true;
String route = plot(nh.basis.getVia(), to, info);
nh.mark = false;
if (nh.bad) {
return (to);
}
return (nh.basis.getVia() + "/" + route);
}
@Nullable
private Hop getHop(HashSet<String> known, HashMap<String, HashMap<String, Hop>> ht, ProvHop ph) {
if (!known.contains(ph.getFrom())) {
errors.add(ph + " references unknown from node");
return null;
}
if (!known.contains(ph.getTo())) {
errors.add(ph + " references unknown destination node");
return null;
}
HashMap<String, Hop> ht2 = ht.get(ph.getTo());
Hop hop = ht2.get(ph.getFrom());
if (hop != null) {
hop.bad = true;
errors.add(ph + " gives duplicate next hop - previous via was " + hop.basis.getVia());
return null;
}
hop = new Hop();
hop.basis = ph;
ht2.put(ph.getFrom(), hop);
if (!known.contains(ph.getVia())) {
errors.add(ph + " references unknown via node");
hop.bad = true;
return null;
}
return hop;
}
private static class Hop {
boolean mark;
boolean bad;
NodeConfig.ProvHop basis;
}
}
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