src/java/iotcloud/Table.java

   1 package iotcloud;
   2 import java.util.HashMap;
   3 import java.util.Map;
   4 import java.util.Iterator;
   5 import java.util.HashSet;
   6 import java.util.Arrays;
   7 import java.util.Vector;
   8
   9 /**
  10  * IoTTable data structure.  Provides client inferface.
  11  * @author Brian Demsky
  12  * @version 1.0
  13  */
  14
  15
  16 final public class Table {
  17         private int numslots;
  18         private HashMap<IoTString, KeyValue> table=new HashMap<IoTString, KeyValue>();
  19         private HashMap<Long, Pair<Long, Liveness> > lastmessagetable=new HashMap<Long, Pair<Long, Liveness> >();
  20         private HashMap<Long, HashSet<RejectedMessage> > watchlist = new HashMap<Long, HashSet<RejectedMessage> >();
  21         private SlotBuffer buffer;
  22         private CloudComm cloud;
  23         private long sequencenumber;
  24         private long localmachineid;
  25         private TableStatus lastTableStatus;
  26         static final int FREE_SLOTS = 10;
  27         static final int FORCED_RESIZE_INCREMENT = 20;
  28
  29         public Table(String baseurl, String password, long _localmachineid) {
  30                 localmachineid=_localmachineid;
  31                 buffer = new SlotBuffer();
  32                 numslots = buffer.capacity();
  33                 sequencenumber = 0;
  34                 cloud=new CloudComm(baseurl, password);
  35         }
  36
  37         public Table(CloudComm _cloud, long _localmachineid) {
  38                 localmachineid=_localmachineid;
  39                 buffer = new SlotBuffer();
  40                 numslots = buffer.capacity();
  41                 sequencenumber = 0;
  42                 cloud=_cloud;
  43         }
  44
  45         public void rebuild() {
  46                 Slot[] newslots=cloud.getSlots(sequencenumber+1);
  47                 validateandupdate(newslots, true);
  48         }
  49
  50         public void update() {
  51                 Slot[] newslots=cloud.getSlots(sequencenumber+1);
  52
  53                 validateandupdate(newslots, false);
  54         }
  55
  56         public IoTString get(IoTString key) {
  57                 KeyValue kv=table.get(key);
  58                 if (kv != null)
  59                         return kv.getValue();
  60                 else
  61                         return null;
  62         }
  63
  64         public void initTable() {
  65                 Slot s=new Slot(1, localmachineid);
  66                 TableStatus status=new TableStatus(s, numslots);
  67                 s.addEntry(status);
  68                 Slot[] array=cloud.putSlot(s, numslots);
  69                 if (array == null) {
  70                         array = new Slot[] {s};
  71                         /* update data structure */
  72                         validateandupdate(array, true);
  73                 } else {
  74                         throw new Error("Error on initialization");
  75                 }
  76         }
  77
  78         public IoTString put(IoTString key, IoTString value) {
  79                 while(true) {
  80                         KeyValue oldvalue=table.get(key);
  81                         if (tryput(key, value, false)) {
  82                                 if (oldvalue==null)
  83                                         return null;
  84                                 else
  85                                         return oldvalue.getValue();
  86                         }
  87                 }
  88         }
  89
  90         private boolean tryput(IoTString key, IoTString value, boolean forcedresize) {
  91                 Slot s=new Slot(sequencenumber+1, localmachineid, buffer.getSlot(sequencenumber).getHMAC());
  92                 long seqn = buffer.getOldestSeqNum();
  93
  94                 if (forcedresize) {
  95                         TableStatus status=new TableStatus(s, FORCED_RESIZE_INCREMENT + numslots);
  96                         s.addEntry(status);
  97                 }
  98
  99                 if ((numslots - buffer.size()) < FREE_SLOTS) {
 100                         /* have to check whether we have enough free slots */
 101                         long fullfirstseqn = buffer.getNewestSeqNum() + 1 - numslots;
 102                         seqn = fullfirstseqn < 1?1:fullfirstseqn;
 103                         for(int i=0; i < FREE_SLOTS; i++, seqn++) {
 104                                 Slot prevslot=buffer.getSlot(seqn);
 105                                 if (!prevslot.isLive())
 106                                         continue;
 107                                 Vector<Entry> liveentries = prevslot.getLiveEntries();
 108                                 for(Entry liveentry:liveentries) {
 109                                         if (redundant(liveentry))
 110                                                 continue;
 111                                         if (s.hasSpace(liveentry))
 112                                                 s.addEntry(liveentry);
 113                                         else if (i==0) {
 114                                                 if (s.canFit(liveentry))
 115                                                         s.addEntry(liveentry);
 116                                                 else if (!forcedresize) {
 117                                                         return tryput(key, value, true);
 118                                                 }
 119                                         }
 120                                 }
 121                         }
 122                 }
 123                 KeyValue kv=new KeyValue(s, key, value);
 124                 boolean insertedkv=false;
 125                 if (s.hasSpace(kv)) {
 126                         s.addEntry(kv);
 127                         insertedkv=true;
 128                 }
 129
 130                 long newestseqnum=buffer.getNewestSeqNum();
 131 search:
 132                 for(; seqn<=newestseqnum; seqn++) {
 133                         Slot prevslot=buffer.getSlot(seqn);
 134                         if (!prevslot.isLive())
 135                                 continue;
 136                         Vector<Entry> liveentries = prevslot.getLiveEntries();
 137                         for(Entry liveentry:liveentries) {
 138                                 if (redundant(liveentry))
 139                                         continue;
 140                                 if (s.hasSpace(liveentry))
 141                                         s.addEntry(liveentry);
 142                                 else
 143                                         break search;
 144                         }
 145                 }
 146
 147                 int max=0;
 148                 if (forcedresize)
 149                         max = numslots + FORCED_RESIZE_INCREMENT;
 150                 Slot[] array=cloud.putSlot(s, max);
 151                 if (array == null)
 152                         array = new Slot[] {s};
 153                 else
 154                         insertedkv=false;
 155
 156                 /* update data structure */
 157                 validateandupdate(array, true);
 158
 159                 return insertedkv;
 160         }
 161
 162         boolean redundant(Entry liveentry) {
 163                 if (liveentry.getType()==Entry.TypeLastMessage) {
 164                         LastMessage lastmsg=(LastMessage) liveentry;
 165                         return lastmsg.getMachineID() == localmachineid;
 166                 }
 167                 return false;
 168         }
 169
 170
 171         private void validateandupdate(Slot[] newslots, boolean acceptupdatestolocal) {
 172                 /* The cloud communication layer has checked slot HMACs already
 173                          before decoding */
 174                 if (newslots.length==0)
 175                         return;
 176
 177                 long firstseqnum=newslots[0].getSequenceNumber();
 178                 if (firstseqnum <= sequencenumber)
 179                         throw new Error("Server Error: Sent older slots!");
 180
 181                 SlotIndexer indexer = new SlotIndexer(newslots, buffer);
 182                 checkHMACChain(indexer, newslots);
 183
 184                 HashSet<Long> machineSet=new HashSet<Long>(lastmessagetable.keySet());
 185
 186                 initExpectedSize();
 187                 for(Slot slot: newslots) {
 188                         updateExpectedSize();
 189                         processSlot(indexer, slot, acceptupdatestolocal, machineSet);
 190                 }
 191
 192                 /* If there is a gap, check to see if the server sent us everything. */
 193                 if (firstseqnum != (sequencenumber+1)) {
 194                         checkNumSlots(newslots.length);
 195                         if (!machineSet.isEmpty())
 196                                 throw new Error("Missing record for machines: "+machineSet);
 197                 }
 198
 199                 commitNewMaxSize();
 200
 201                 /* Commit new to slots. */
 202                 for(Slot slot:newslots) {
 203                         buffer.putSlot(slot);
 204                 }
 205                 sequencenumber = newslots[newslots.length - 1].getSequenceNumber();
 206         }
 207
 208         private int expectedsize, currmaxsize;
 209
 210         private void checkNumSlots(int numslots) {
 211                 if (numslots != expectedsize)
 212                         throw new Error("Server Error: Server did not send all slots.  Expected: "+expectedsize+" Received:"+numslots);
 213         }
 214
 215         private void initExpectedSize() {
 216                 long prevslots = sequencenumber;
 217                 expectedsize = (prevslots < ((long) numslots))?(int) prevslots:numslots;
 218                 currmaxsize = numslots;
 219         }
 220
 221         private void updateExpectedSize() {
 222                 expectedsize++;
 223                 if (expectedsize > currmaxsize)
 224                         expectedsize = currmaxsize;
 225         }
 226
 227         private void updateCurrMaxSize(int newmaxsize) {
 228                 currmaxsize=newmaxsize;
 229         }
 230
 231         private void commitNewMaxSize() {
 232                 if (numslots != currmaxsize)
 233                         buffer.resize(currmaxsize);
 234
 235                 numslots=currmaxsize;
 236         }
 237
 238         private void processEntry(KeyValue entry, SlotIndexer indexer) {
 239                 IoTString key=entry.getKey();
 240                 KeyValue oldvalue=table.get(key);
 241                 if (oldvalue != null) {
 242                         oldvalue.setDead();
 243                 }
 244                 table.put(key, entry);
 245         }
 246
 247         private void processEntry(LastMessage entry, SlotIndexer indexer, HashSet<Long> machineSet) {
 248                 updateLastMessage(entry.getMachineID(), entry.getSequenceNumber(), entry, false, machineSet);
 249         }
 250
 251         private void processEntry(RejectedMessage entry, SlotIndexer indexer) {
 252                 long oldseqnum=entry.getOldSeqNum();
 253                 long newseqnum=entry.getNewSeqNum();
 254                 boolean isequal=entry.getEqual();
 255                 long machineid=entry.getMachineID();
 256                 for(long seqnum=oldseqnum; seqnum<=newseqnum; seqnum++) {
 257                         Slot slot=indexer.getSlot(seqnum);
 258                         if (slot != null) {
 259                                 long slotmachineid=slot.getMachineID();
 260                                 if (isequal!=(slotmachineid==machineid)) {
 261                                         throw new Error("Server Error: Trying to insert rejected message for slot "+seqnum);
 262                                 }
 263                         }
 264                 }
 265
 266                 HashSet<Long> watchset=new HashSet<Long>();
 267                 for(Map.Entry<Long, Pair<Long,Liveness> > lastmsg_entry:lastmessagetable.entrySet()) {
 268                         long entry_mid=lastmsg_entry.getKey();
 269                         /* We've seen it, don't need to continue to watch.  Our next
 270                          * message will implicitly acknowledge it. */
 271                         if (entry_mid == localmachineid)
 272                                 continue;
 273                         Pair<Long, Liveness> v=lastmsg_entry.getValue();
 274                         long entry_seqn=v.getFirst();
 275                         if (entry_seqn < newseqnum) {
 276                                 addWatchList(entry_mid, entry);
 277                                 watchset.add(entry_mid);
 278                         }
 279                 }
 280                 if (watchset.isEmpty())
 281                         entry.setDead();
 282                 else
 283                         entry.setWatchSet(watchset);
 284         }
 285
 286         private void addWatchList(long machineid, RejectedMessage entry) {
 287                 HashSet<RejectedMessage> entries=watchlist.get(machineid);
 288                 if (entries == null)
 289                         watchlist.put(machineid, entries=new HashSet<RejectedMessage>());
 290                 entries.add(entry);
 291         }
 292
 293         private void processEntry(TableStatus entry, SlotIndexer indexer) {
 294                 int newnumslots=entry.getMaxSlots();
 295                 updateCurrMaxSize(newnumslots);
 296                 if (lastTableStatus != null)
 297                         lastTableStatus.setDead();
 298                 lastTableStatus = entry;
 299         }
 300
 301         private void updateLastMessage(long machineid, long seqnum, Liveness liveness, boolean acceptupdatestolocal, HashSet<Long> machineSet) {
 302                 machineSet.remove(machineid);
 303
 304                 HashSet<RejectedMessage> watchset=watchlist.get(machineid);
 305                 if (watchset != null) {
 306                         for(Iterator<RejectedMessage> rmit=watchset.iterator(); rmit.hasNext(); ) {
 307                                 RejectedMessage rm=rmit.next();
 308                                 if (rm.getNewSeqNum() <= seqnum) {
 309                                         /* Remove it from our watchlist */
 310                                         rmit.remove();
 311                                         /* Decrement machines that need to see this notification */
 312                                         rm.removeWatcher(machineid);
 313                                 }
 314                         }
 315                 }
 316
 317                 Pair<Long, Liveness> lastmsgentry = lastmessagetable.put(machineid, new Pair<Long, Liveness>(seqnum, liveness));
 318                 if (lastmsgentry == null)
 319                         return;
 320
 321                 long lastmsgseqnum = lastmsgentry.getFirst();
 322                 Liveness lastentry = lastmsgentry.getSecond();
 323                 if (lastentry instanceof LastMessage) {
 324                         ((LastMessage)lastentry).setDead();
 325                 } else if (lastentry instanceof Slot) {
 326                         ((Slot)lastentry).setDead();
 327                 } else {
 328                         throw new Error("Unrecognized type");
 329                 }
 330
 331                 if (machineid == localmachineid) {
 332                         if (lastmsgseqnum != seqnum && !acceptupdatestolocal)
 333                                 throw new Error("Server Error: Mismatch on local machine sequence number");
 334                 } else {
 335                         if (lastmsgseqnum > seqnum)
 336                                 throw new Error("Server Error: Rollback on remote machine sequence number");
 337                 }
 338         }
 339
 340         private void processSlot(SlotIndexer indexer, Slot slot, boolean acceptupdatestolocal, HashSet<Long> machineSet) {
 341                 updateLastMessage(slot.getMachineID(), slot.getSequenceNumber(), slot, acceptupdatestolocal, machineSet);
 342
 343                 for(Entry entry : slot.getEntries()) {
 344                         switch(entry.getType()) {
 345                         case Entry.TypeKeyValue:
 346                                 processEntry((KeyValue)entry, indexer);
 347                                 break;
 348
 349                         case Entry.TypeLastMessage:
 350                                 processEntry((LastMessage)entry, indexer, machineSet);
 351                                 break;
 352
 353                         case Entry.TypeRejectedMessage:
 354                                 processEntry((RejectedMessage)entry, indexer);
 355                                 break;
 356
 357                         case Entry.TypeTableStatus:
 358                                 processEntry((TableStatus)entry, indexer);
 359                                 break;
 360
 361                         default:
 362                                 throw new Error("Unrecognized type: "+entry.getType());
 363                         }
 364                 }
 365         }
 366
 367         private void checkHMACChain(SlotIndexer indexer, Slot[] newslots) {
 368                 for(int i=0; i < newslots.length; i++) {
 369                         Slot currslot=newslots[i];
 370                         Slot prevslot=indexer.getSlot(currslot.getSequenceNumber()-1);
 371                         if (prevslot != null &&
 372                                         !Arrays.equals(prevslot.getHMAC(), currslot.getPrevHMAC()))
 373                                 throw new Error("Server Error: Invalid HMAC Chain"+currslot+" "+prevslot);
 374                 }
 375         }
 376 }