cadi/client/src/main/java/org/onap/aaf/cadi/locator/HotPeerLocator.java

   1 /**
   2  * ============LICENSE_START====================================================
   3  * org.onap.aaf
   4  * ===========================================================================
   5  * Copyright (c) 2018 AT&T Intellectual Property. All rights reserved.
   6  * ===========================================================================
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *      http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  * ============LICENSE_END====================================================
  19  *
  20  */
  21
  22 package org.onap.aaf.cadi.locator;
  23
  24 import org.onap.aaf.cadi.Access;
  25 import org.onap.aaf.cadi.Locator;
  26 import org.onap.aaf.cadi.LocatorException;
  27 import org.onap.aaf.cadi.Access.Level;
  28 import org.onap.aaf.cadi.routing.GreatCircle;
  29 import org.onap.aaf.misc.env.util.Split;
  30
  31 /**
  32  * This Locator is to handle Hot Peer load protection, when the Servers are
  33  *      1) Static
  34  *      2) Well known client URL
  35  *
  36  * The intention is to change traffic over to the Hot Peer, if a server goes down, and reinstate
  37  * when it is back up.
  38  *
  39  * Example of this kind of Service is a MS Certificate Server
  40  *
  41  * @author Jonathan
  42  *
  43  * @param <CLIENT>
  44  */
  45 public abstract class HotPeerLocator<CLIENT> implements Locator<CLIENT> {
  46         private final String[] urlstrs;
  47         private final CLIENT[] clients;
  48         private final long[] failures;
  49         private final double[] distances;
  50         private int preferred;
  51         private long invalidateTime;
  52         private Thread refreshThread;
  53         protected Access access;
  54
  55         /**
  56          * Construct:  Expect one or more Strings in the form:
  57          *    192.555.112.223:39/38.88087/-77.30122
  58          *    separated by commas
  59          *
  60          * @param trans
  61          * @param urlstr
  62          * @param invalidateTime
  63          * @param localLatitude
  64          * @param localLongitude
  65          * @throws LocatorException
  66          */
  67         @SuppressWarnings("unchecked")
  68         protected HotPeerLocator(Access access, final String urlstr, final long invalidateTime, final String localLatitude, final String localLongitude) throws LocatorException {
  69                 this.access = access;
  70                  urlstrs = Split.split(',', urlstr);
  71                  clients = (CLIENT[])new Object[urlstrs.length];
  72                  failures = new long[urlstrs.length];
  73                  distances= new double[urlstrs.length];
  74                  this.invalidateTime = invalidateTime;
  75
  76                  double distance = Double.MAX_VALUE;
  77                  for(int i=0;i<urlstrs.length;++i) {
  78                          String[] info = Split.split('/', urlstrs[i]);
  79                          if(info.length<3) {
  80                                  throw new LocatorException("Configuration needs LAT and LONG, i.e. ip:port/lat/long");
  81                          }
  82                          try {
  83                                  clients[i] = _newClient(urlstrs[i]);
  84                                  failures[i] = 0L;
  85                          } catch(LocatorException le) {
  86                                  failures[i] = System.currentTimeMillis()+invalidateTime;
  87                          }
  88
  89                          double d = GreatCircle.calc(info[1],info[2],localLatitude,localLongitude);
  90                          distances[i]=d;
  91
  92                          // find preferred server
  93                          if(d<distance) {
  94                                  preferred = i;
  95                                  distance=d;
  96                          }
  97                  }
  98
  99                  access.printf(Level.INIT,"Preferred Client is %s",urlstrs[preferred]);
 100                  for(int i=0;i<urlstrs.length;++i) {
 101                          if(i!=preferred) {
 102                                  access.printf(Level.INIT,"Alternate Client is %s",urlstrs[i]);
 103                          }
 104                  }
 105         }
 106
 107         protected abstract CLIENT _newClient(String hostInfo) throws LocatorException;
 108         /**
 109          * If client can reconnect, then return.  Otherwise, destroy and return null;
 110          * @param client
 111          * @return
 112          * @throws LocatorException
 113          */
 114         protected abstract CLIENT _invalidate(CLIENT client);
 115
 116         protected abstract void _destroy(CLIENT client);
 117
 118         @Override
 119         public Item best() throws LocatorException {
 120                 if(failures[preferred]==0L) {
 121                         return new HPItem(preferred);
 122                 } else {
 123                         long now = System.currentTimeMillis();
 124                         double d = Double.MAX_VALUE;
 125                         int best = -1;
 126                         boolean tickle = false;
 127                         // try for best existing client
 128                         for(int i=0;i<urlstrs.length;++i) {
 129                                 if(failures[i]<now && distances[i]<d) {
 130                                         if(clients[i]!=null) {
 131                                                 best = i;
 132                                                 break;
 133                                         } else {
 134                                                 tickle = true; // There's some failed clients which can be restored
 135                                         }
 136                                 }
 137                         }
 138                         if(best<0 && tickle) {
 139                                 tickle=false;
 140                                 if(refresh()) {
 141                                         // try again
 142                                         for(int i=0;i<urlstrs.length;++i) {
 143                                                 if(failures[i]==0L && distances[i]<d) {
 144                                                         if(clients[i]!=null) {
 145                                                                 best = i;
 146                                                                 break;
 147                                                         }
 148                                                 }
 149                                         }
 150                                 }
 151                         }
 152
 153                         /*
 154                          * If a valid client is available, but there are some that can refresh, return the client immediately
 155                          * but start a Thread to do the background Client setup.
 156                          */
 157                         if(tickle) {
 158                                 synchronized(clients) {
 159                                         if(refreshThread==null) {
 160                                                 refreshThread = new Thread(new Runnable(){
 161                                                         @Override
 162                                                         public void run() {
 163                                                                 refresh();
 164                                                                 refreshThread = null;
 165                                                         }
 166                                                 });
 167                                                 refreshThread.setDaemon(true);
 168                                                 refreshThread.start();
 169                                         }
 170                                 }
 171                         }
 172
 173                         if(best<0) {
 174                                 throw new LocatorException("No Clients available");
 175                         }
 176
 177                         return new HPItem(best);
 178                 }
 179         }
 180
 181
 182         @Override
 183         public CLIENT get(Item item) throws LocatorException {
 184                 HPItem hpi = (HPItem)item;
 185                 CLIENT c = clients[hpi.idx];
 186                 if(c==null) {
 187                         if(failures[hpi.idx]>System.currentTimeMillis()) {
 188                                 throw new LocatorException("Client requested is invalid");
 189                         } else {
 190                                 synchronized(clients) {
 191                                         c = _newClient(urlstrs[hpi.idx]);
 192                                         failures[hpi.idx]=0L;
 193                                 }
 194                         }
 195                 } else if(failures[hpi.idx]>0){
 196                         throw new LocatorException("Client requested is invalid");
 197                 }
 198                 return c;
 199         }
 200
 201         public String info(Item item) {
 202                 HPItem hpi = (HPItem)item;
 203                 if(hpi!=null && hpi.idx<urlstrs.length) {
 204                         return urlstrs[hpi.idx];
 205                 } else {
 206                         return "Invalid Item";
 207                 }
 208         }
 209
 210         @Override
 211         public boolean hasItems() {
 212                 for(int i=0;i<clients.length;++i) {
 213                         if(clients[i]!=null && failures[i]==0L) {
 214                                 return true;
 215                         }
 216                 }
 217                 return false;
 218         }
 219
 220         @Override
 221         public synchronized void invalidate(Item item) throws LocatorException {
 222                 HPItem hpi = (HPItem)item;
 223                 failures[hpi.idx] = System.currentTimeMillis() + invalidateTime;
 224                 CLIENT c = clients[hpi.idx];
 225                 clients[hpi.idx] = _invalidate(c);
 226         }
 227
 228         @Override
 229         public Item first() throws LocatorException {
 230                 return new HPItem(0);
 231         }
 232
 233         @Override
 234         public Item next(Item item) throws LocatorException {
 235                 HPItem hpi = (HPItem)item;
 236                 if(++hpi.idx>=clients.length) {
 237                         return null;
 238                 }
 239                 return hpi;
 240         }
 241
 242         @Override
 243         public boolean refresh() {
 244                 boolean force = !hasItems(); // If no Items at all, reset
 245                 boolean rv = true;
 246                 long now = System.currentTimeMillis();
 247                 for(int i=0;i<clients.length;++i) {
 248                         if(failures[i]>0L && (failures[i]<now || force)) { // retry
 249                                 try {
 250                                         synchronized(clients) {
 251                                                 if(clients[i]==null) {
 252                                                         clients[i]=_newClient(urlstrs[i]);
 253                                                 }
 254                                                 failures[i]=0L;
 255                                         }
 256                                 } catch (LocatorException e) {
 257                                         failures[i]=now+invalidateTime;
 258                                         rv = false;
 259                                 }
 260                         }
 261                 }
 262                 return rv;
 263         }
 264
 265         @Override
 266         public void destroy() {
 267                 for(int i=0;i<clients.length;++i) {
 268                         if(clients[i]!=null) {
 269                                 _destroy(clients[i]);
 270                                 clients[i] = null;
 271                         }
 272                 }
 273         }
 274
 275         private static class HPItem implements Item {
 276                 private int idx;
 277
 278                 public HPItem(int i) {
 279                         idx = i;
 280                 }
 281         }
 282
 283
 284         /*
 285          * Convenience Functions
 286          */
 287         public CLIENT bestClient() throws LocatorException {
 288                 return get(best());
 289         }
 290
 291         public boolean invalidate(CLIENT client) throws LocatorException {
 292                 for(int i=0;i<clients.length;++i) {
 293                         if(clients[i]==client) { // yes, "==" is appropriate here.. Comparing Java Object Reference
 294                                 invalidate(new HPItem(i));
 295                                 return true;
 296                         }
 297                 }
 298                 return false;
 299         }
 300
 301 }