client/src/main/java/com/att/cadi/locator/HotPeerLocator.java

   1 /*******************************************************************************\r
   2  * ============LICENSE_START====================================================\r
   3  * * org.onap.aaf\r
   4  * * ===========================================================================\r
   5  * * Copyright © 2017 AT&T Intellectual Property. All rights reserved.\r
   6  * * ===========================================================================\r
   7  * * Licensed under the Apache License, Version 2.0 (the "License");\r
   8  * * you may not use this file except in compliance with the License.\r
   9  * * You may obtain a copy of the License at\r
  10  * * \r
  11  *  *      http://www.apache.org/licenses/LICENSE-2.0\r
  12  * * \r
  13  *  * Unless required by applicable law or agreed to in writing, software\r
  14  * * distributed under the License is distributed on an "AS IS" BASIS,\r
  15  * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
  16  * * See the License for the specific language governing permissions and\r
  17  * * limitations under the License.\r
  18  * * ============LICENSE_END====================================================\r
  19  * *\r
  20  * * ECOMP is a trademark and service mark of AT&T Intellectual Property.\r
  21  * *\r
  22  ******************************************************************************/\r
  23 package com.att.cadi.locator;\r
  24 \r
  25 import com.att.cadi.Access;\r
  26 import com.att.cadi.Access.Level;\r
  27 import com.att.cadi.Locator;\r
  28 import com.att.cadi.LocatorException;\r
  29 import com.att.cadi.routing.GreatCircle;\r
  30 import com.att.inno.env.util.Split;\r
  31 \r
  32 /**\r
  33  * This Locator is to handle Hot Peer load protection, when the Servers are \r
  34  *      1) Static\r
  35  *      2) Well known client URL\r
  36  * \r
  37  * The intention is to change traffic over to the Hot Peer, if a server goes down, and reinstate\r
  38  * when it is back up.\r
  39  * \r
  40  * Example of this kind of Service is a MS Certificate Server\r
  41  * \r
  42  *\r
  43  *\r
  44  * @param <CLIENT>\r
  45  */\r
  46 public abstract class HotPeerLocator<CLIENT> implements Locator<CLIENT> {\r
  47                 private final String[] urlstrs;\r
  48                 private final CLIENT[] clients;\r
  49                 private final long[] failures;\r
  50                 private final double[] distances;\r
  51                 private int preferred;\r
  52                 private long invalidateTime;\r
  53                 private Thread refreshThread;\r
  54                 protected Access access;\r
  55 \r
  56                 /**\r
  57                  * Construct:  Expect one or more Strings in the form:\r
  58                  *              192.555.112.223:39/38.88087/-77.30122\r
  59                  *    separated by commas\r
  60                  * \r
  61                  * @param trans\r
  62                  * @param urlstr\r
  63                  * @param invalidateTime\r
  64                  * @param localLatitude\r
  65                  * @param localLongitude\r
  66                  * @throws LocatorException\r
  67                  */\r
  68                 @SuppressWarnings("unchecked")\r
  69                 protected HotPeerLocator(Access access, final String urlstr, final long invalidateTime, final String localLatitude, final String localLongitude) throws LocatorException {\r
  70                         this.access = access;\r
  71                         urlstrs = Split.split(',', urlstr);\r
  72                         clients = (CLIENT[])new Object[urlstrs.length];\r
  73                         failures = new long[urlstrs.length];\r
  74                         distances= new double[urlstrs.length];\r
  75                         this.invalidateTime = invalidateTime;\r
  76                         \r
  77                         double distance = Double.MAX_VALUE;\r
  78                         for(int i=0;i<urlstrs.length;++i) {\r
  79                                 String[] info = Split.split('/', urlstrs[i]);\r
  80                                 if(info.length<3) {\r
  81                                         throw new LocatorException("Configuration needs LAT and LONG, i.e. ip:port/lat/long");\r
  82                                 }\r
  83                                 try {\r
  84                                         clients[i] = _newClient(urlstrs[i]);\r
  85                                         failures[i] = 0L;\r
  86                                 } catch(LocatorException le) {\r
  87                                         failures[i] = System.currentTimeMillis()+invalidateTime;\r
  88                                 }\r
  89                                 \r
  90                                 double d = GreatCircle.calc(info[1],info[2],localLatitude,localLongitude);\r
  91                                 distances[i]=d;\r
  92                                 \r
  93                                 // find preferred server\r
  94                                 if(d<distance) {\r
  95                                         preferred = i;\r
  96                                         distance=d;\r
  97                                 }\r
  98                         }\r
  99                         \r
 100                         access.printf(Level.INIT,"Preferred Client is %s",urlstrs[preferred]);\r
 101                         for(int i=0;i<urlstrs.length;++i) {\r
 102                                 if(i!=preferred) {\r
 103                                         access.printf(Level.INIT,"Alternate Client is %s",urlstrs[i]);\r
 104                                 }\r
 105                         }\r
 106                 }\r
 107                 \r
 108                 protected abstract CLIENT _newClient(String hostInfo) throws LocatorException;\r
 109                 /**\r
 110                  * If client can reconnect, then return.  Otherwise, destroy and return null;\r
 111                  * @param client\r
 112                  * @return\r
 113                  * @throws LocatorException\r
 114                  */\r
 115                 protected abstract CLIENT _invalidate(CLIENT client);\r
 116                 \r
 117                 protected abstract void _destroy(CLIENT client);\r
 118                 \r
 119                 @Override\r
 120                 public Item best() throws LocatorException {\r
 121                         if(failures[preferred]==0L) {\r
 122                                 return new HPItem(preferred);\r
 123                         } else {\r
 124                                 long now = System.currentTimeMillis();\r
 125                                 double d = Double.MAX_VALUE;\r
 126                                 int best = -1;\r
 127                                 boolean tickle = false;\r
 128                                 // try for best existing client\r
 129                                 for(int i=0;i<urlstrs.length;++i) {\r
 130                                         if(failures[i]<now && distances[i]<d) {\r
 131                                                 if(clients[i]!=null) {\r
 132                                                         best = i;\r
 133                                                         break;\r
 134                                                 } else {\r
 135                                                         tickle = true; // There's some failed clients which can be restored\r
 136                                                 }\r
 137                                         }\r
 138                                 }\r
 139                                 if(best<0 && tickle) {\r
 140                                         tickle=false;\r
 141                                         if(refresh()) {\r
 142                                                 // try again\r
 143                                                 for(int i=0;i<urlstrs.length;++i) {\r
 144                                                         if(failures[i]==0L && distances[i]<d) {\r
 145                                                                 if(clients[i]!=null) {\r
 146                                                                         best = i;\r
 147                                                                         break;\r
 148                                                                 }\r
 149                                                         }\r
 150                                                 }\r
 151                                         }\r
 152                                 }\r
 153                         \r
 154                                 /*\r
 155                                  * If a valid client is available, but there are some that can refresh, return the client immediately\r
 156                                  * but start a Thread to do the background Client setup.\r
 157                                  */\r
 158                                 if(tickle) {\r
 159                                         synchronized(clients) {\r
 160                                                 if(refreshThread==null) {\r
 161                                                         refreshThread = new Thread(new Runnable(){\r
 162                                                                 @Override\r
 163                                                                 public void run() {\r
 164                                                                         refresh();\r
 165                                                                         refreshThread = null;\r
 166                                                                 }\r
 167                                                         });\r
 168                                                         refreshThread.setDaemon(true);\r
 169                                                         refreshThread.start();\r
 170                                                 }\r
 171                                         }\r
 172                                 }\r
 173                                 \r
 174                                 if(best<0) {\r
 175                                         throw new LocatorException("No Clients available");\r
 176                                 }\r
 177 \r
 178                                 \r
 179                                 return new HPItem(best);\r
 180                         }\r
 181                 }\r
 182                 \r
 183 \r
 184                 @Override\r
 185                 public CLIENT get(Item item) throws LocatorException {\r
 186                         HPItem hpi = (HPItem)item;\r
 187                         CLIENT c = clients[hpi.idx];\r
 188                         if(c==null) {\r
 189                                 if(failures[hpi.idx]>System.currentTimeMillis()) {\r
 190                                         throw new LocatorException("Client requested is invalid");      \r
 191                                 } else {\r
 192                                         synchronized(clients) {\r
 193                                                 c = _newClient(urlstrs[hpi.idx]);\r
 194                                                 failures[hpi.idx]=0L;\r
 195                                         }\r
 196                                 }\r
 197                         } else if(failures[hpi.idx]>0){\r
 198                                 throw new LocatorException("Client requested is invalid");\r
 199                         }\r
 200                         return c;\r
 201                 }\r
 202                 \r
 203                 public String info(Item item) {\r
 204                         HPItem hpi = (HPItem)item;\r
 205                         if(hpi!=null && hpi.idx<urlstrs.length) {\r
 206                                 return urlstrs[hpi.idx];\r
 207                         } else {\r
 208                                 return "Invalid Item";\r
 209                         }\r
 210                 }\r
 211 \r
 212                 @Override\r
 213                 public boolean hasItems() {\r
 214                         for(int i=0;i<clients.length;++i) {\r
 215                                 if(clients[i]!=null && failures[i]==0L) {\r
 216                                         return true;\r
 217                                 }\r
 218                         }\r
 219                         return false;\r
 220                 }\r
 221                 \r
 222                 @Override\r
 223                 public synchronized void invalidate(Item item) throws LocatorException {\r
 224                         HPItem hpi = (HPItem)item;\r
 225                         failures[hpi.idx] = System.currentTimeMillis() + invalidateTime;\r
 226                         CLIENT c = clients[hpi.idx];\r
 227                         clients[hpi.idx] = _invalidate(c);\r
 228                 }\r
 229                 \r
 230                 @Override\r
 231                 public Item first() throws LocatorException {\r
 232                         return new HPItem(0);\r
 233                 }\r
 234                 \r
 235                 @Override\r
 236                 public Item next(Item item) throws LocatorException {\r
 237                         HPItem hpi = (HPItem)item;\r
 238                         if(++hpi.idx>=clients.length) {\r
 239                                 return null;\r
 240                         }\r
 241                         return hpi;\r
 242                 }\r
 243                 \r
 244                 @Override\r
 245                 public boolean refresh() {\r
 246                         boolean force = !hasItems(); // If no Items at all, reset\r
 247                         boolean rv = true;\r
 248                         long now = System.currentTimeMillis();\r
 249                         for(int i=0;i<clients.length;++i) {\r
 250                                 if(failures[i]>0L && (failures[i]<now || force)) { // retry\r
 251                                         try {\r
 252                                                 synchronized(clients) {\r
 253                                                         if(clients[i]==null) {\r
 254                                                                 clients[i]=_newClient(urlstrs[i]);\r
 255                                                         }\r
 256                                                         failures[i]=0L;\r
 257                                                 }\r
 258                                         } catch (LocatorException e) {\r
 259                                                 failures[i]=now+invalidateTime;\r
 260                                                 rv = false;\r
 261                                         }\r
 262                                 }\r
 263                         }\r
 264                         return rv;\r
 265                 }\r
 266                 \r
 267                 @Override\r
 268                 public void destroy() {\r
 269                         for(int i=0;i<clients.length;++i) {\r
 270                                 if(clients[i]!=null) {\r
 271                                         _destroy(clients[i]);\r
 272                                         clients[i] = null;\r
 273                                 }\r
 274                         }\r
 275                 }\r
 276 \r
 277                 private static class HPItem implements Item {\r
 278                         private int idx;\r
 279 \r
 280                         public HPItem(int i) {\r
 281                                 idx = i;\r
 282                         }\r
 283                 }\r
 284                 \r
 285 \r
 286                 /*\r
 287                  * Convenience Functions\r
 288                  */\r
 289                 public CLIENT bestClient() throws LocatorException {\r
 290                         return get(best());\r
 291                 }\r
 292 \r
 293                 public boolean invalidate(CLIENT client) throws LocatorException {\r
 294                         for(int i=0;i<clients.length;++i) {\r
 295                                 if(clients[i]==client) { // yes, "==" is appropriate here.. Comparing Java Object Reference\r
 296                                         invalidate(new HPItem(i));\r
 297                                         return true;\r
 298                                 }\r
 299                         }\r
 300                         return false;\r
 301                 }\r
 302 \r
 303         }\r