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/*
* ============LICENSE_START==========================================
* org.onap.music
* ===================================================================
* Copyright (c) 2019 AT&T Intellectual Property
* ===================================================================
* 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.music.main;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class DeadlockDetectionUtil {
private Map<String, Node> nodeList = null;
public enum OwnershipType {NONE, CREATED, ACQUIRED};
private class Node implements Comparable<Node> {
private String id;
private List<Node> links;
private boolean visited = false;
private boolean onStack = false;
@Override
public String toString() {
StringBuffer sb = new StringBuffer();
for (Node link : links)
sb.append(link.id);
return "Node [id=" + id + ", links=" + sb.toString() + ", visited=" + visited + ", onStack=" + onStack + "]";
}
public Node(String id) {
super();
this.id = id;
this.links = new ArrayList<>();
}
public List<Node> getLinks() {
return links;
}
public void addLink(Node link) {
this.links.add(link);
}
public void removeLink(Node link) {
this.links.remove(link);
}
public boolean isVisited() {
return visited;
}
public boolean isOnStack() {
return onStack;
}
public void setVisited(boolean visited) {
this.visited = visited;
}
public void setOnStack(boolean onStack) {
this.onStack = onStack;
}
@Override
public int compareTo(Node arg0) {
return id.compareTo(arg0.id);
}
}
public DeadlockDetectionUtil() {
this.nodeList = new HashMap<>();
}
public void listAllNodes() {
System.out.println("In DeadlockDetectionUtil: ");
for (String key : nodeList.keySet()) {
System.out.println(" " + key + " : " + nodeList.get(key));
}
}
public boolean checkForDeadlock(String resource, String owner, OwnershipType operation) {
setExisting(resource, owner, operation);
Node currentNode = null;
if (operation.equals(OwnershipType.ACQUIRED)) {
currentNode = nodeList.get("r" + resource);
} else if (operation.equals(OwnershipType.CREATED)) {
currentNode = nodeList.get("o" + owner);
}
return findCycle(currentNode);
}
private boolean findCycle(Node currentNode) {
if (currentNode==null)
return false;
if (currentNode.isOnStack())
return true;
if (currentNode.isVisited())
return false;
currentNode.setOnStack(true);
currentNode.setVisited(true);
for (Node childNode : currentNode.getLinks()) {
if (findCycle(childNode))
return true;
}
currentNode.setOnStack(false);
return false;
}
public void setExisting(String resource, String owner, OwnershipType operation) {
String resourceKey = "r" + resource;
Node resourceNode = nodeList.get(resourceKey);
if (resourceNode==null) {
resourceNode = new Node(resourceKey);
nodeList.put(resourceKey, resourceNode);
}
String ownerKey = "o" + owner;
Node ownerNode = nodeList.get(ownerKey);
if (ownerNode==null) {
ownerNode = new Node(ownerKey);
nodeList.put(ownerKey, ownerNode);
}
if (operation.equals(OwnershipType.ACQUIRED)) {
resourceNode.addLink(ownerNode);
ownerNode.removeLink(resourceNode);
} else if (operation.equals(OwnershipType.CREATED)) {
ownerNode.addLink(resourceNode);
resourceNode.removeLink(ownerNode);
}
}
}
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