opendaylight/networkconfiguration/neutron/northbound/src/main/java/org/opendaylight/controller/networkconfig/neutron/northbound/PaginatedRequestFactory.java

   1 /*
   2  * Copyright (C) 2014 Red Hat, Inc.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  *
   8  *  Authors : Dave Tucker
   9  */
  10
  11 package org.opendaylight.controller.networkconfig.neutron.northbound;
  12
  13 import java.util.ArrayList;
  14 import java.util.Collections;
  15 import java.util.Comparator;
  16 import java.util.List;
  17 import javax.ws.rs.core.UriInfo;
  18
  19 import org.opendaylight.controller.networkconfig.neutron.INeutronObject;
  20 import org.opendaylight.controller.networkconfig.neutron.NeutronNetwork;
  21 import org.opendaylight.controller.networkconfig.neutron.NeutronPort;
  22 import org.opendaylight.controller.networkconfig.neutron.NeutronSubnet;
  23
  24 public class PaginatedRequestFactory {
  25     private static final Comparator<INeutronObject> NEUTRON_OBJECT_COMPARATOR = new Comparator<INeutronObject>() {
  26         @Override
  27         public int compare(INeutronObject o1, INeutronObject o2) {
  28             return o1.getID().compareTo(o2.getID());
  29         }
  30     };
  31
  32     public static class PaginationResults<T extends INeutronObject> {
  33         List<T> collection;
  34         List<NeutronPageLink> links;
  35
  36         public PaginationResults(List<T> collection, List<NeutronPageLink> links) {
  37             this.collection = collection;
  38             this.links = links;
  39         }
  40     }
  41
  42     private static final class MarkerObject implements INeutronObject {
  43         private final String id;
  44
  45         MarkerObject(String id) {
  46             this.id = id;
  47         }
  48
  49         @Override
  50         public String getID() {
  51             return id;
  52         }
  53
  54         @Override
  55         public void setID(String id) {
  56             throw new UnsupportedOperationException("Marker has constant ID");
  57         }
  58     }
  59
  60     /*
  61      * SuppressWarnings is needed because the compiler does not understand that we
  62      * are actually safe here.
  63      *
  64      * FIXME: the only caller performs a cast back, so this is not actually necessary.
  65      */
  66     @SuppressWarnings("unchecked")
  67     public static <T extends INeutronObject> INeutronRequest<T> createRequest(Integer limit, String marker,
  68                                                                            Boolean pageReverse,
  69                                                                            UriInfo uriInfo,
  70                                                                            List<T> collection,
  71                                                                            Class<T> clazz) {
  72         PaginationResults<T> results = _paginate(limit, marker, pageReverse, uriInfo, collection);
  73
  74         if (clazz.equals(NeutronNetwork.class)){
  75             return (INeutronRequest<T>) new NeutronNetworkRequest((List<NeutronNetwork>) results.collection, results.links);
  76         }
  77         if (clazz.equals(NeutronSubnet.class)){
  78             return (INeutronRequest<T>) new NeutronSubnetRequest((List<NeutronSubnet>) results.collection, results.links);
  79         }
  80         if (clazz.equals(NeutronPort.class)){
  81             return (INeutronRequest<T>) new NeutronPortRequest((List<NeutronPort>) results.collection, results.links);
  82         }
  83         return null;
  84     }
  85
  86     private static <T extends INeutronObject> PaginationResults<T> _paginate(Integer limit, String marker, Boolean pageReverse, UriInfo uriInfo, List<T> collection) {
  87         List<NeutronPageLink> links = new ArrayList<>();
  88         final int startPos;
  89         String startMarker;
  90         String endMarker;
  91         Boolean firstPage = false;
  92         Boolean lastPage = false;
  93
  94         Collections.sort(collection, NEUTRON_OBJECT_COMPARATOR);
  95
  96         if (marker != null) {
  97             int offset = Collections.binarySearch(collection, new MarkerObject(marker), NEUTRON_OBJECT_COMPARATOR);
  98             if (offset < 0) {
  99                 throw new ResourceNotFoundException("UUID for marker: " + marker + " could not be found");
 100             }
 101
 102             if (!pageReverse) {
 103                 startPos = offset + 1;
 104             }
 105             else {
 106                 startPos = offset - limit;
 107             }
 108         }
 109         else {
 110             startPos = 0;
 111         }
 112
 113         if (startPos == 0){
 114             firstPage = true;
 115         }
 116
 117         if (startPos + limit >= collection.size()) {
 118             collection = collection.subList(startPos, collection.size());
 119             startMarker = collection.get(0).getID();
 120             endMarker = collection.get(collection.size() - 1).getID();
 121             lastPage = true;
 122         }
 123         else if (startPos < 0) {
 124             if (startPos + limit > 0) {
 125                 collection = collection.subList(0, startPos + limit);
 126                 startMarker = collection.get(0).getID();
 127                 endMarker = collection.get(collection.size() - 1).getID();
 128                 firstPage = true;
 129             }
 130             else {
 131                 throw new BadRequestException("Requested page is out of bounds. Please check the supplied limit and marker");
 132             }
 133         }
 134         else {
 135             collection = collection.subList(startPos, startPos + limit);
 136             startMarker = collection.get(0).getID();
 137             endMarker = collection.get(limit-1).getID();
 138         }
 139
 140         if (!lastPage) {
 141             NeutronPageLink next = new NeutronPageLink();
 142             next.setRef("next");
 143             next.setHref(uriInfo.getAbsolutePath().toString() + "?limit=" + limit.toString() + "&marker=" + endMarker);
 144             links.add(next);
 145         }
 146
 147         if (!firstPage) {
 148             NeutronPageLink previous = new NeutronPageLink();
 149             previous.setRef("previous");
 150             previous.setHref(uriInfo.getAbsolutePath().toString() + "?limit=" + limit.toString() + "&marker=" + startMarker + "&page_reverse=True");
 151             links.add(previous);
 152         }
 153
 154         return new PaginationResults<T>(collection, links);
 155     }
 156 }