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 import java.util.Random;
   9
  10 /**
  11  * IoTTable data structure.  Provides client inferface.
  12  * @author Brian Demsky
  13  * @version 1.0
  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 Vector<Long> rejectedmessagelist=new Vector<Long>();
  22         private SlotBuffer buffer;
  23         private CloudComm cloud;
  24         private long sequencenumber;
  25         private long localmachineid;
  26         private TableStatus lastTableStatus;
  27         static final int FREE_SLOTS = 10;
  28         static final int SKIP_THRESHOLD = 10;
  29         private long liveslotcount=0;
  30         private int chance;
  31         static final double RESIZE_MULTIPLE = 1.2;
  32         static final double RESIZE_THRESHOLD = 0.75;
  33         static final int REJECTED_THRESHOLD = 5;
  34         private int resizethreshold;
  35         private long lastliveslotseqn;
  36         private Random random=new Random();
  37
  38         public Table(String baseurl, String password, long _localmachineid) {
  39                 localmachineid=_localmachineid;
  40                 buffer = new SlotBuffer();
  41                 numslots = buffer.capacity();
  42                 setResizeThreshold();
  43                 sequencenumber = 0;
  44                 cloud=new CloudComm(this, baseurl, password);
  45                 lastliveslotseqn = 1;
  46         }
  47
  48         public Table(CloudComm _cloud, long _localmachineid) {
  49                 localmachineid=_localmachineid;
  50                 buffer = new SlotBuffer();
  51                 numslots = buffer.capacity();
  52                 setResizeThreshold();
  53                 sequencenumber = 0;
  54                 cloud=_cloud;
  55         }
  56
  57         public void rebuild() {
  58                 Slot[] newslots=cloud.getSlots(sequencenumber+1);
  59                 validateandupdate(newslots, true);
  60         }
  61
  62         public void update() {
  63                 Slot[] newslots=cloud.getSlots(sequencenumber+1);
  64
  65                 validateandupdate(newslots, false);
  66         }
  67
  68         public IoTString get(IoTString key) {
  69                 KeyValue kv=table.get(key);
  70                 if (kv != null)
  71                         return kv.getValue();
  72                 else
  73                         return null;
  74         }
  75
  76         public void initTable() {
  77                 cloud.setSalt();//Set the salt
  78                 Slot s=new Slot(this, 1, localmachineid);
  79                 TableStatus status=new TableStatus(s, numslots);
  80                 s.addEntry(status);
  81                 Slot[] array=cloud.putSlot(s, numslots);
  82                 if (array == null) {
  83                         array = new Slot[] {s};
  84                         /* update data structure */
  85                         validateandupdate(array, true);
  86                 } else {
  87                         throw new Error("Error on initialization");
  88                 }
  89         }
  90
  91         public String toString() {
  92                 return table.toString();
  93         }
  94
  95         public IoTString put(IoTString key, IoTString value) {
  96                 while(true) {
  97                         KeyValue oldvalue=table.get(key);
  98                         if (tryput(key, value, false)) {
  99                                 if (oldvalue==null)
 100                                         return null;
 101                                 else
 102                                         return oldvalue.getValue();
 103                         }
 104                 }
 105         }
 106
 107         void decrementLiveCount() {
 108                 liveslotcount--;
 109         }
 110
 111         private void setResizeThreshold() {
 112                 int resize_lower=(int) (RESIZE_THRESHOLD * numslots);
 113                 resizethreshold=resize_lower-1+random.nextInt(numslots-resize_lower);
 114         }
 115
 116         private boolean tryput(IoTString key, IoTString value, boolean resize) {
 117                 Slot s=new Slot(this, sequencenumber+1, localmachineid, buffer.getSlot(sequencenumber).getHMAC());
 118                 int newsize = 0;
 119                 if (liveslotcount > resizethreshold) {
 120                         resize=true;
 121                         newsize = (int) (numslots * RESIZE_MULTIPLE);
 122                 }
 123
 124                 if (resize) {
 125                         newsize = (int) (numslots * RESIZE_MULTIPLE);
 126                         TableStatus status=new TableStatus(s, newsize);
 127                         s.addEntry(status);
 128                 }
 129
 130                 if (!rejectedmessagelist.isEmpty()) {
 131                         long old_seqn=rejectedmessagelist.firstElement();
 132                         if (rejectedmessagelist.size() > REJECTED_THRESHOLD) {
 133                                 long new_seqn=rejectedmessagelist.lastElement();
 134                                 RejectedMessage rm=new RejectedMessage(s, localmachineid, old_seqn, new_seqn, false);
 135                                 s.addEntry(rm);
 136                         } else {
 137                                 long prev_seqn=-1;
 138                                 int i=0;
 139                                 /* Go through list of missing messages */
 140                                 for(;i<rejectedmessagelist.size();i++) {
 141                                         long curr_seqn=rejectedmessagelist.get(i);
 142                                         Slot s_msg=buffer.getSlot(curr_seqn);
 143                                         if (s_msg!=null)
 144                                                 break;
 145                                         prev_seqn=curr_seqn;
 146                                 }
 147                                 /* Generate rejected message entry for missing messages */
 148                                 if (prev_seqn != -1) {
 149                                         RejectedMessage rm=new RejectedMessage(s, localmachineid, old_seqn, prev_seqn, false);
 150                                         s.addEntry(rm);
 151                                 }
 152                                 /* Generate rejected message entries for present messages */
 153                                 for(;i<rejectedmessagelist.size();i++) {
 154                                         long curr_seqn=rejectedmessagelist.get(i);
 155                                         Slot s_msg=buffer.getSlot(curr_seqn);
 156                                         long machineid=s_msg.getMachineID();
 157                                         RejectedMessage rm=new RejectedMessage(s, machineid, curr_seqn, curr_seqn, true);
 158                                         s.addEntry(rm);
 159                                 }
 160                         }
 161                 }
 162
 163                 long newestseqnum = buffer.getNewestSeqNum();
 164                 long oldestseqnum = buffer.getOldestSeqNum();
 165                 if (lastliveslotseqn < oldestseqnum)
 166                         lastliveslotseqn = oldestseqnum;
 167
 168                 long seqn = lastliveslotseqn;
 169                 boolean seenliveslot = false;
 170                 long firstiffull = newestseqnum + 1 - numslots;
 171                 long threshold = firstiffull + FREE_SLOTS;
 172
 173                 for(; seqn < threshold; seqn++) {
 174                         Slot prevslot=buffer.getSlot(seqn);
 175                         //Push slot number forward
 176                         if (!seenliveslot)
 177                                 lastliveslotseqn = seqn;
 178
 179                         if (!prevslot.isLive())
 180                                 continue;
 181                         seenliveslot = true;
 182                         Vector<Entry> liveentries = prevslot.getLiveEntries(resize);
 183                         for(Entry liveentry:liveentries) {
 184                                 if (s.hasSpace(liveentry)) {
 185                                         s.addEntry(liveentry);
 186                                 } else if (seqn==firstiffull) {
 187                                         if (!resize) {
 188                                                 System.out.print("B");
 189                                                 return tryput(key, value, true);
 190                                         }
 191                                 }
 192                         }
 193                 }
 194
 195                 KeyValue kv=new KeyValue(s, key, value);
 196                 boolean insertedkv=false;
 197                 if (s.hasSpace(kv)) {
 198                         s.addEntry(kv);
 199                         insertedkv=true;
 200                 }
 201
 202                 int skipcount=0;
 203                 search:
 204                 for(; seqn <= newestseqnum; seqn++) {
 205                         Slot prevslot=buffer.getSlot(seqn);
 206                         //Push slot number forward
 207                         if (!seenliveslot)
 208                                 lastliveslotseqn = seqn;
 209
 210                         if (!prevslot.isLive())
 211                                 continue;
 212                         seenliveslot = true;
 213                         Vector<Entry> liveentries = prevslot.getLiveEntries(resize);
 214                         for(Entry liveentry:liveentries) {
 215                                 if (s.hasSpace(liveentry))
 216                                         s.addEntry(liveentry);
 217                                 else {
 218                                         skipcount++;
 219                                         if (skipcount > SKIP_THRESHOLD)
 220                                                 break search;
 221                                 }
 222                         }
 223                 }
 224
 225                 int max=0;
 226                 if (resize)
 227                         max = newsize;
 228                 Slot[] array=cloud.putSlot(s, max);
 229                 if (array == null) {
 230                         array = new Slot[] {s};
 231                         rejectedmessagelist.clear();
 232                 }       else {
 233                         if (array.length == 0)
 234                                 throw new Error("Server Error: Did not send any slots");
 235                         rejectedmessagelist.add(s.getSequenceNumber());
 236                         insertedkv=false;
 237                 }
 238
 239                 /* update data structure */
 240                 validateandupdate(array, true);
 241
 242                 return insertedkv;
 243         }
 244
 245         private void validateandupdate(Slot[] newslots, boolean acceptupdatestolocal) {
 246                 /* The cloud communication layer has checked slot HMACs already
 247                          before decoding */
 248                 if (newslots.length==0)
 249                         return;
 250
 251                 long firstseqnum=newslots[0].getSequenceNumber();
 252                 if (firstseqnum <= sequencenumber)
 253                         throw new Error("Server Error: Sent older slots!");
 254
 255                 SlotIndexer indexer = new SlotIndexer(newslots, buffer);
 256                 checkHMACChain(indexer, newslots);
 257
 258                 HashSet<Long> machineSet=new HashSet<Long>(lastmessagetable.keySet());
 259
 260                 initExpectedSize(firstseqnum);
 261                 for(Slot slot: newslots) {
 262                         processSlot(indexer, slot, acceptupdatestolocal, machineSet);
 263                         updateExpectedSize();
 264                 }
 265
 266                 /* If there is a gap, check to see if the server sent us everything. */
 267                 if (firstseqnum != (sequencenumber+1)) {
 268                         checkNumSlots(newslots.length);
 269                         if (!machineSet.isEmpty())
 270                                 throw new Error("Missing record for machines: "+machineSet);
 271                 }
 272
 273                 commitNewMaxSize();
 274
 275                 /* Commit new to slots. */
 276                 for(Slot slot:newslots) {
 277                         buffer.putSlot(slot);
 278                         liveslotcount++;
 279                 }
 280                 sequencenumber = newslots[newslots.length - 1].getSequenceNumber();
 281         }
 282
 283         private int expectedsize, currmaxsize;
 284
 285         private void checkNumSlots(int numslots) {
 286                 if (numslots != expectedsize)
 287                         throw new Error("Server Error: Server did not send all slots.  Expected: "+expectedsize+" Received:"+numslots);
 288         }
 289
 290         private void initExpectedSize(long firstsequencenumber) {
 291                 long prevslots = firstsequencenumber;
 292                 expectedsize = (prevslots < ((long) numslots))?(int) prevslots:numslots;
 293                 currmaxsize = numslots;
 294         }
 295
 296         private void updateExpectedSize() {
 297                 expectedsize++;
 298                 if (expectedsize > currmaxsize)
 299                         expectedsize = currmaxsize;
 300         }
 301
 302         private void updateCurrMaxSize(int newmaxsize) {
 303                 currmaxsize=newmaxsize;
 304         }
 305
 306         private void commitNewMaxSize() {
 307                 if (numslots != currmaxsize)
 308                         buffer.resize(currmaxsize);
 309
 310                 numslots=currmaxsize;
 311                 setResizeThreshold();
 312         }
 313
 314         private void processEntry(KeyValue entry, SlotIndexer indexer) {
 315                 IoTString key=entry.getKey();
 316                 KeyValue oldvalue=table.get(key);
 317                 if (oldvalue != null) {
 318                         oldvalue.setDead();
 319                 }
 320                 table.put(key, entry);
 321         }
 322
 323         private void processEntry(LastMessage entry, SlotIndexer indexer, HashSet<Long> machineSet) {
 324                 updateLastMessage(entry.getMachineID(), entry.getSequenceNumber(), entry, false, machineSet);
 325         }
 326
 327         private void processEntry(RejectedMessage entry, SlotIndexer indexer) {
 328                 long oldseqnum=entry.getOldSeqNum();
 329                 long newseqnum=entry.getNewSeqNum();
 330                 boolean isequal=entry.getEqual();
 331                 long machineid=entry.getMachineID();
 332                 for(long seqnum=oldseqnum; seqnum<=newseqnum; seqnum++) {
 333                         Slot slot=indexer.getSlot(seqnum);
 334                         if (slot != null) {
 335                                 long slotmachineid=slot.getMachineID();
 336                                 if (isequal!=(slotmachineid==machineid)) {
 337                                         throw new Error("Server Error: Trying to insert rejected message for slot "+seqnum);
 338                                 }
 339                         }
 340                 }
 341
 342                 HashSet<Long> watchset=new HashSet<Long>();
 343                 for(Map.Entry<Long, Pair<Long,Liveness> > lastmsg_entry:lastmessagetable.entrySet()) {
 344                         long entry_mid=lastmsg_entry.getKey();
 345                         /* We've seen it, don't need to continue to watch.  Our next
 346                          * message will implicitly acknowledge it. */
 347                         if (entry_mid == localmachineid)
 348                                 continue;
 349                         Pair<Long, Liveness> v=lastmsg_entry.getValue();
 350                         long entry_seqn=v.getFirst();
 351                         if (entry_seqn < newseqnum) {
 352                                 addWatchList(entry_mid, entry);
 353                                 watchset.add(entry_mid);
 354                         }
 355                 }
 356                 if (watchset.isEmpty())
 357                         entry.setDead();
 358                 else
 359                         entry.setWatchSet(watchset);
 360         }
 361
 362         private void addWatchList(long machineid, RejectedMessage entry) {
 363                 HashSet<RejectedMessage> entries=watchlist.get(machineid);
 364                 if (entries == null)
 365                         watchlist.put(machineid, entries=new HashSet<RejectedMessage>());
 366                 entries.add(entry);
 367         }
 368
 369         private void processEntry(TableStatus entry, SlotIndexer indexer) {
 370                 int newnumslots=entry.getMaxSlots();
 371                 updateCurrMaxSize(newnumslots);
 372                 if (lastTableStatus != null)
 373                         lastTableStatus.setDead();
 374                 lastTableStatus = entry;
 375         }
 376
 377         private void updateLastMessage(long machineid, long seqnum, Liveness liveness, boolean acceptupdatestolocal, HashSet<Long> machineSet) {
 378                 machineSet.remove(machineid);
 379
 380                 HashSet<RejectedMessage> watchset=watchlist.get(machineid);
 381                 if (watchset != null) {
 382                         for(Iterator<RejectedMessage> rmit=watchset.iterator(); rmit.hasNext(); ) {
 383                                 RejectedMessage rm=rmit.next();
 384                                 if (rm.getNewSeqNum() <= seqnum) {
 385                                         /* Remove it from our watchlist */
 386                                         rmit.remove();
 387                                         /* Decrement machines that need to see this notification */
 388                                         rm.removeWatcher(machineid);
 389                                 }
 390                         }
 391                 }
 392
 393                 if (machineid == localmachineid) {
 394                         /* Our own messages are immediately dead. */
 395                         if (liveness instanceof LastMessage) {
 396                                 ((LastMessage)liveness).setDead();
 397                         } else if (liveness instanceof Slot) {
 398                                 ((Slot)liveness).setDead();
 399                         } else {
 400                                 throw new Error("Unrecognized type");
 401                         }
 402                 }
 403
 404
 405                 Pair<Long, Liveness> lastmsgentry = lastmessagetable.put(machineid, new Pair<Long, Liveness>(seqnum, liveness));
 406                 if (lastmsgentry == null)
 407                         return;
 408
 409                 long lastmsgseqnum = lastmsgentry.getFirst();
 410                 Liveness lastentry = lastmsgentry.getSecond();
 411                 if (machineid != localmachineid) {
 412                         if (lastentry instanceof LastMessage) {
 413                                 ((LastMessage)lastentry).setDead();
 414                         } else if (lastentry instanceof Slot) {
 415                                 ((Slot)lastentry).setDead();
 416                         } else {
 417                                 throw new Error("Unrecognized type");
 418                         }
 419                 }
 420
 421                 if (machineid == localmachineid) {
 422                         if (lastmsgseqnum != seqnum && !acceptupdatestolocal)
 423                                 throw new Error("Server Error: Mismatch on local machine sequence number");
 424                 } else {
 425                         if (lastmsgseqnum > seqnum)
 426                                 throw new Error("Server Error: Rollback on remote machine sequence number");
 427                 }
 428         }
 429
 430         private void processSlot(SlotIndexer indexer, Slot slot, boolean acceptupdatestolocal, HashSet<Long> machineSet) {
 431                 updateLastMessage(slot.getMachineID(), slot.getSequenceNumber(), slot, acceptupdatestolocal, machineSet);
 432                 for(Entry entry : slot.getEntries()) {
 433                         switch(entry.getType()) {
 434                         case Entry.TypeKeyValue:
 435                                 processEntry((KeyValue)entry, indexer);
 436                                 break;
 437
 438                         case Entry.TypeLastMessage:
 439                                 processEntry((LastMessage)entry, indexer, machineSet);
 440                                 break;
 441
 442                         case Entry.TypeRejectedMessage:
 443                                 processEntry((RejectedMessage)entry, indexer);
 444                                 break;
 445
 446                         case Entry.TypeTableStatus:
 447                                 processEntry((TableStatus)entry, indexer);
 448                                 break;
 449
 450                         default:
 451                                 throw new Error("Unrecognized type: "+entry.getType());
 452                         }
 453                 }
 454         }
 455
 456         private void checkHMACChain(SlotIndexer indexer, Slot[] newslots) {
 457                 for(int i=0; i < newslots.length; i++) {
 458                         Slot currslot=newslots[i];
 459                         Slot prevslot=indexer.getSlot(currslot.getSequenceNumber()-1);
 460                         if (prevslot != null &&
 461                                         !Arrays.equals(prevslot.getHMAC(), currslot.getPrevHMAC()))
 462                                 throw new Error("Server Error: Invalid HMAC Chain"+currslot+" "+prevslot);
 463                 }
 464         }
 465 }