1 files changed, 152 insertions, 0 deletions
diff --git a/music-core/src/main/java/org/onap/music/main/DeadlockDetectionUtil.java b/music-core/src/main/java/org/onap/music/main/DeadlockDetectionUtil.java
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+++ b/music-core/src/main/java/org/onap/music/main/DeadlockDetectionUtil.java
@@ -0,0 +1,152 @@
+/*
+ * ============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);
+		}
+	}
+
+}