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Diffstat (limited to 'framework/src/onos/utils/misc/src/main/java/org/onlab/graph/KshortestPathSearch.java')
-rw-r--r-- | framework/src/onos/utils/misc/src/main/java/org/onlab/graph/KshortestPathSearch.java | 286 |
1 files changed, 0 insertions, 286 deletions
diff --git a/framework/src/onos/utils/misc/src/main/java/org/onlab/graph/KshortestPathSearch.java b/framework/src/onos/utils/misc/src/main/java/org/onlab/graph/KshortestPathSearch.java deleted file mode 100644 index 820e912c..00000000 --- a/framework/src/onos/utils/misc/src/main/java/org/onlab/graph/KshortestPathSearch.java +++ /dev/null @@ -1,286 +0,0 @@ -/* - * Copyright 2014-2015 Open Networking Laboratory - * - * 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. - */ -package org.onlab.graph; - -import java.util.ArrayList; -//import java.util.HashMap; -import java.util.Iterator; -import java.util.List; -//import java.util.Map; -//import java.util.PriorityQueue; -import java.util.Set; - -import static org.onlab.graph.GraphPathSearch.ALL_PATHS; - -/** - * K-shortest-path graph search algorithm capable of finding not just one, - * but K shortest paths with ascending order between the source and destinations. - */ - -public class KshortestPathSearch<V extends Vertex, E extends Edge<V>> { - - // Define class variables. - private Graph<V, E> immutableGraph; - private MutableGraph<V, E> mutableGraph; - private List<List<E>> pathResults = new ArrayList<List<E>>(); - private List<List<E>> pathCandidates = new ArrayList<List<E>>(); - private V source; - private V sink; - private int numK = 0; - private EdgeWeight<V, E> weight = null; - // private PriorityQueue<List<E>> pathCandidates = new PriorityQueue<List<E>>(); - - // Initialize the graph. - public KshortestPathSearch(Graph<V, E> graph) { - immutableGraph = graph; - mutableGraph = new MutableAdjacencyListsGraph<>(graph.getVertexes(), - graph.getEdges()); - } - - public List<List<E>> search(V src, - V dst, - EdgeWeight<V, E> wei, - int k) { - - weight = wei; - source = src; - sink = dst; - numK = k; - // pathCandidates = new PriorityQueue<List<E>>(); - - pathResults.clear(); - pathCandidates.clear(); - - // Double check the parameters - checkArguments(immutableGraph, src, dst, numK); - - // DefaultResult result = new DefaultResult(src, dst); - - searchKShortestPaths(); - - return pathResults; - } - - private void checkArguments(Graph<V, E> graph, V src, V dst, int k) { - if (graph == null) { - throw new NullPointerException("graph is null"); - } - if (!graph.getVertexes().contains(src)) { - throw new NullPointerException("source node does not exist"); - } - if (!graph.getVertexes().contains(dst)) { - throw new NullPointerException("target node does not exist"); - } - if (k <= 0) { - throw new NullPointerException("K is negative or 0"); - } - if (weight == null) { - throw new NullPointerException("the cost matrix is null"); - } - } - - private void searchKShortestPaths() { - // Step 1: find the shortest path. - List<E> shortestPath = searchShortestPath(immutableGraph, source, sink); - // no path exists, exit. - if (shortestPath == null) { - return; - } - - // Step 2: update the results. - pathResults.add(shortestPath); - // pathCandidates.add(shortestPath); - - // Step 3: find the other K-1 paths. - while (/*pathCandidates.size() > 0 &&*/pathResults.size() < numK) { - // 3.1 the spur node ranges from the first node to the last node in the previous k-shortest path. - List<E> lastPath = pathResults.get(pathResults.size() - 1); - for (int i = 0; i < lastPath.size(); i++) { - // 3.1.1 convert the graph into mutable. - convertGraph(); - // 3.1.2 transform the graph. - List<E> rootPath = createSpurNode(lastPath, i); - transformGraph(rootPath); - // 3.1.3 find the deviation node. - V devNode; - devNode = getDevNode(rootPath); - List<E> spurPath; - // 3.1.4 find the shortest path in the transformed graph. - spurPath = searchShortestPath(mutableGraph, devNode, sink); - // 3.1.5 update the path candidates. - if (spurPath != null) { - // totalPath = rootPath + spurPath; - rootPath.addAll(spurPath); - pathCandidates.add(rootPath); - } - } - // 3.2 if there is no spur path, exit. - if (pathCandidates.size() == 0) { - break; - } - // 3.3 add the path into the results. - addPathResult(); - } - } - - @SuppressWarnings({ "rawtypes", "unchecked" }) - private List<E> searchShortestPath(Graph<V, E> graph, V src, V dst) { - // Determine the shortest path from the source to the destination by using the Dijkstra algorithm. - DijkstraGraphSearch dijkstraAlg = new DijkstraGraphSearch(); - Set<Path> paths = dijkstraAlg.search(graph, src, dst, weight, ALL_PATHS).paths(); - Iterator<Path> itr = paths.iterator(); - if (!itr.hasNext()) { - return null; - } - // return the first shortest path only. - return (List<E>) itr.next().edges(); - } - - private void convertGraph() { - // clear the mutableGraph first - if (mutableGraph != null) { - ((MutableAdjacencyListsGraph) mutableGraph).clear(); - } - - // create a immutableGraph - Set<E> copyEa = immutableGraph.getEdges(); - Set<V> copyVa = immutableGraph.getVertexes(); - for (V vertex : copyVa) { - mutableGraph.addVertex(vertex); - } - for (E edge : copyEa) { - mutableGraph.addEdge(edge); - } - } - - private V getDevNode(List<E> path) { - V srcA; - V dstB; - - if (path.size() == 0) { - return source; - } - - E temp1 = path.get(path.size() - 1); - srcA = temp1.src(); - dstB = temp1.dst(); - - if (path.size() == 1) { - if (srcA.equals(source)) { - return dstB; - } else { - return srcA; - } - } else { - E temp2 = path.get(path.size() - 2); - if (srcA.equals(temp2.src()) || srcA.equals(temp2.dst())) { - return dstB; - } else { - return srcA; - } - } - } - - private List<E> createSpurNode(List<E> path, int n) { - List<E> root = new ArrayList<E>(); - - for (int i = 0; i < n; i++) { - root.add(path.get(i)); - } - return root; - } - - private void transformGraph(List<E> rootPath) { - List<E> prePath; - //remove edges - for (int i = 0; i < pathResults.size(); i++) { - prePath = pathResults.get(i); - if (prePath.size() == 1) { - mutableGraph.removeEdge(prePath.get(0)); - } else if (comparePath(rootPath, prePath)) { - for (int j = 0; j <= rootPath.size(); j++) { - mutableGraph.removeEdge(prePath.get(j)); - } - } - } - for (int i = 0; i < pathCandidates.size(); i++) { - prePath = pathCandidates.get(i); - if (prePath.size() == 1) { - mutableGraph.removeEdge(prePath.get(0)); - } else if (comparePath(rootPath, prePath)) { - for (int j = 0; j <= rootPath.size(); j++) { - mutableGraph.removeEdge(prePath.get(j)); - } - } - } - - if (rootPath.size() == 0) { - return; - } - - //remove nodes - List<V> nodes = new ArrayList<V>(); - nodes.add(source); - V pre = source; - V srcA; - V dstB; - for (int i = 0; i < rootPath.size() - 1; i++) { - E temp = rootPath.get(i); - srcA = temp.src(); - dstB = temp.dst(); - - if (srcA.equals(pre)) { - nodes.add(dstB); - pre = dstB; - } else { - nodes.add(srcA); - pre = srcA; - } - } - for (int i = 0; i < nodes.size(); i++) { - mutableGraph.removeVertex(nodes.get(i)); - } - } - - private boolean comparePath(List<E> path1, List<E> path2) { - if (path1.size() > path2.size()) { - return false; - } - if (path1.size() == 0) { - return true; - } - for (int i = 0; i < path1.size(); i++) { - if (path1.get(i) != path2.get(i)) { - return false; - } - } - return true; - } - - private void addPathResult() { - List<E> sp; - sp = pathCandidates.get(0); - for (int i = 1; i < pathCandidates.size(); i++) { - if (sp.size() > pathCandidates.get(i).size()) { - sp = pathCandidates.get(i); - } - } - pathResults.add(sp); - // Log.info(sp.toString()); - pathCandidates.remove(sp); - } - -} |