Robust/src/Runtime/DSTM/interface/dstmserver.c

   1 /* Coordinator => Machine that initiates the transaction request call for commiting a transaction
   2  * Participant => Machines that host the objects involved in a transaction commit */
   3
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <pthread.h>
   8 #include <netdb.h>
   9 #include <fcntl.h>
  10 #include "dstm.h"
  11 #include "mlookup.h"
  12 #include "llookup.h"
  13
  14 #define LISTEN_PORT 2156
  15 #define BACKLOG 10 //max pending connections
  16 #define RECEIVE_BUFFER_SIZE 2048
  17 #define PRE_BUF_SIZE 2048
  18
  19 extern int classsize[];
  20
  21 objstr_t *mainobjstore;
  22
  23 int dstmInit(void)
  24 {
  25         /* Initialize main object store */
  26         mainobjstore = objstrCreate(DEFAULT_OBJ_STORE_SIZE);
  27         /* Create machine lookup table and location lookup table */
  28         if (mhashCreate(HASH_SIZE, LOADFACTOR))
  29                 return 1; //failure
  30
  31         if (lhashCreate(HASH_SIZE, LOADFACTOR))
  32                 return 1; //failure
  33
  34         return 0;
  35 }
  36
  37 void *dstmListen()
  38 {
  39         int listenfd, acceptfd;
  40         struct sockaddr_in my_addr;
  41         struct sockaddr_in client_addr;
  42         socklen_t addrlength = sizeof(struct sockaddr);
  43         pthread_t thread_dstm_accept;
  44         int i;
  45         int setsockflag=1;
  46
  47         listenfd = socket(AF_INET, SOCK_STREAM, 0);
  48         if (listenfd == -1)
  49         {
  50                 perror("socket");
  51                 exit(1);
  52         }
  53
  54         if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &setsockflag, sizeof (setsockflag)) < 0) {
  55           perror("socket");
  56           exit(1);
  57         }
  58 #ifdef MAC
  59         if (setsockopt(listenfd, SOL_SOCKET, SO_NOSIGPIPE, &setsockflag, sizeof (setsockflag)) < 0) {
  60           perror("socket");
  61           exit(1);
  62         }
  63 #endif
  64
  65         my_addr.sin_family = AF_INET;
  66         my_addr.sin_port = htons(LISTEN_PORT);
  67         my_addr.sin_addr.s_addr = INADDR_ANY;
  68         memset(&(my_addr.sin_zero), '\0', 8);
  69
  70         if (bind(listenfd, (struct sockaddr *)&my_addr, addrlength) == -1)
  71         {
  72                 perror("bind");
  73                 exit(1);
  74         }
  75
  76         if (listen(listenfd, BACKLOG) == -1)
  77         {
  78                 perror("listen");
  79                 exit(1);
  80         }
  81
  82         printf("Listening on port %d, fd = %d\n", LISTEN_PORT, listenfd);
  83         while(1)
  84         {
  85                 acceptfd = accept(listenfd, (struct sockaddr *)&client_addr, &addrlength);
  86                 pthread_create(&thread_dstm_accept, NULL, dstmAccept, (void *)acceptfd);
  87         }
  88         pthread_exit(NULL);
  89 }
  90 /* This function accepts a new connection request, decodes the control message in the connection
  91  * and accordingly calls other functions to process new requests */
  92 void *dstmAccept(void *acceptfd)
  93 {
  94         int numbytes,i, val, retval;
  95         unsigned int oid;
  96         char buffer[RECEIVE_BUFFER_SIZE], control,ctrl;
  97         char *ptr;
  98         void *srcObj;
  99         objheader_t *h;
 100         trans_commit_data_t transinfo;
 101
 102         int fd_flags = fcntl((int)acceptfd, F_GETFD), size;
 103
 104         printf("Recieved connection: fd = %d\n", (int)acceptfd);
 105         /* Receive control messages from other machines */
 106         if((retval = recv((int)acceptfd, &control, sizeof(char), 0)) <= 0) {
 107                 if (retval == 0) {
 108                         return; // Testing connection
 109                 }
 110                 perror("Error in receiving control from coordinator\n");
 111                 return;
 112         }
 113
 114         switch(control) {
 115                 case READ_REQUEST:
 116                         /* Read oid requested and search if available */
 117                         if((retval = recv((int)acceptfd, &oid, sizeof(unsigned int), 0)) <= 0) {
 118                                 perror("Error receiving object from cooridnator\n");
 119                                 return NULL;
 120                         }
 121                         srcObj = mhashSearch(oid);
 122                         h = (objheader_t *) srcObj;
 123                         size = sizeof(objheader_t) + sizeof(classsize[h->type]);
 124                         if (h == NULL) {
 125                                 ctrl = OBJECT_NOT_FOUND;
 126                                 if(send((int)acceptfd, &ctrl, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
 127                                         perror("Error sending control msg to coordinator\n");
 128                                         return NULL;
 129                                 }
 130                         } else {
 131                                 /* Type */
 132                           char msg[]={OBJECT_FOUND, 0, 0, 0, 0};
 133                           *((int *)&msg[1])=size;
 134                           if(send((int)acceptfd, &msg, sizeof(msg), MSG_NOSIGNAL) < sizeof(msg)) {
 135                                   perror("Error sending size of object to coordinator\n");
 136                                   return NULL;
 137                           }
 138                           if(send((int)acceptfd, h, size, MSG_NOSIGNAL) < size) {
 139                                   perror("Error in sending object\n");
 140                                   return NULL;
 141                           }
 142                         }
 143                         break;
 144
 145                 case READ_MULT_REQUEST:
 146                         printf("DEBUG-> READ_MULT_REQUEST\n");
 147                         break;
 148
 149                 case MOVE_REQUEST:
 150                         printf("DEBUG -> MOVE_REQUEST\n");
 151                         break;
 152
 153                 case MOVE_MULT_REQUEST:
 154                         printf("DEBUG -> MOVE_MULT_REQUEST\n");
 155                         break;
 156
 157                 case TRANS_REQUEST:
 158                         /* Read transaction request */
 159                         printf("DEBUG -> Recv TRANS_REQUEST\n");
 160                         if((val = readClientReq(&transinfo, (int)acceptfd)) != 0) {
 161                                 printf("Error in readClientReq\n");
 162                                 return;
 163                         }
 164                         break;
 165                 case TRANS_PREFETCH:
 166                         printf("DEBUG -> Recv TRANS_PREFETCH\n");
 167                         if((val = prefetchReq((int)acceptfd)) != 0) {
 168                                 printf("Error in readClientReq\n");
 169                                 return;
 170                         }
 171                         break;
 172
 173                 default:
 174                         printf("DEBUG -> dstmAccept: Error Unknown opcode %d\n", control);
 175         }
 176
 177         /* Close connection */
 178         if (close((int)acceptfd) == -1)
 179                 perror("close");
 180         else
 181                 printf("Closed connection: fd = %d\n", (int)acceptfd);
 182
 183         pthread_exit(NULL);
 184 }
 185
 186 /* This function reads the information available in a transaction request
 187  * and makes a function call to process the request */
 188 int readClientReq(trans_commit_data_t *transinfo, int acceptfd) {
 189         char *ptr;
 190         void *modptr;
 191         fixed_data_t fixed;
 192         int sum = 0, i, N, n, val;
 193
 194         /* Read fixed_data_t data structure */
 195         N = sizeof(fixed) - 1;
 196         ptr = (char *)&fixed;;
 197         fixed.control = TRANS_REQUEST;
 198         do {
 199                 n = recv((int)acceptfd, (void *) ptr+1+sum, N-sum, 0);
 200                 sum += n;
 201         } while(sum < N && n != 0);
 202
 203         /* Read list of mids */
 204         int mcount = fixed.mcount;
 205         N = mcount * sizeof(unsigned int);
 206         unsigned int listmid[mcount];
 207         ptr = (char *) listmid;
 208         sum = 0;
 209         do {
 210                 n = recv((int)acceptfd, (void *) ptr+sum, N-sum, 0);
 211                 sum += n;
 212         } while(sum < N && n != 0);
 213
 214         /* Read oid and version tuples for those objects that are not modified in the transaction */
 215         int numread = fixed.numread;
 216         N = numread * (sizeof(unsigned int) + sizeof(short));
 217         char objread[N];
 218         if(numread != 0) { //If pile contains more than one object to be read,
 219                           // keep reading all objects
 220                 sum = 0;
 221                 do {
 222                         n = recv((int)acceptfd, (void *) objread, N, 0);
 223                         sum += n;
 224                 } while(sum < N && n != 0);
 225         }
 226
 227         /* Read modified objects */
 228         if(fixed.nummod != 0) { // If pile contains more than one modified object,
 229                                 // allocate new object store and recv all modified objects
 230                                 // TODO deallocate this space
 231                 if ((modptr = objstrAlloc(mainobjstore, fixed.sum_bytes)) == NULL) {
 232                         printf("objstrAlloc error for modified objects %s, %d\n", __FILE__, __LINE__);
 233                         return 1;
 234                 }
 235                 sum = 0;
 236                 do { // Recv the objs that are modified by the Coordinator
 237                         n = recv((int)acceptfd, modptr+sum, fixed.sum_bytes-sum, 0);
 238                         sum += n;
 239                 } while (sum < fixed.sum_bytes && n != 0);
 240         }
 241
 242         /*Process the information read */
 243         if((val = processClientReq(&fixed, transinfo, listmid, objread, modptr, acceptfd)) != 0) {
 244                 printf("Error in processClientReq %s, %d\n", __FILE__, __LINE__);
 245                 return 1;
 246         }
 247
 248         return 0;
 249 }
 250
 251 /* This function processes the Coordinator's transaction request using "handleTransReq"
 252  * function and sends a reply to the co-ordinator.
 253  * Following this it also receives a new control message from the co-ordinator and processes this message*/
 254 int processClientReq(fixed_data_t *fixed, trans_commit_data_t *transinfo,
 255                 unsigned int *listmid, char *objread, void *modptr, int acceptfd) {
 256         char *ptr, control, sendctrl;
 257         objheader_t *tmp_header;
 258         void *header;
 259         int  i = 0, val, retval;
 260
 261         /* Send reply to the Coordinator */
 262         if((retval = handleTransReq(fixed, transinfo, listmid, objread, modptr,acceptfd)) == 0 ) {
 263                 printf("Handle Trans Req error %s, %d\n", __FILE__, __LINE__);
 264                 return 1;
 265         }
 266         /* Read new control message from Coordiator */
 267         if((retval = recv((int)acceptfd, &control, sizeof(char), 0)) <= 0 ) {
 268                 perror("Error in receiving control message\n");
 269                 return 1;
 270         }
 271
 272         /* Process the new control message */
 273         switch(control) {
 274                 case TRANS_ABORT:
 275                         /* Set all ref counts as 1 and do garbage collection */
 276                         ptr = modptr;
 277                         for(i = 0; i< fixed->nummod; i++) {
 278                                 tmp_header = (objheader_t *)ptr;
 279                                 tmp_header->rcount = 1;
 280                                 ptr += sizeof(objheader_t) + classsize[tmp_header->type];
 281                         }
 282                         /* Unlock objects that was locked due to this transaction */
 283                         for(i = 0; i< transinfo->numlocked; i++) {
 284                                 header = mhashSearch(transinfo->objlocked[i]);// find the header address
 285                                 ((objheader_t *)header)->status &= ~(LOCK);
 286                         }
 287
 288                         /* Send ack to Coordinator */
 289                         printf("DEBUG -> Recv TRANS_ABORT\n");
 290                         sendctrl = TRANS_SUCESSFUL;
 291                         if(send((int)acceptfd, &sendctrl, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
 292                                 perror("Error sending ACK to coordinator\n");
 293                                 return 1;
 294                         }
 295                         ptr = NULL;
 296         //              return 0;
 297                         break;
 298
 299                 case TRANS_COMMIT:
 300                         /* Invoke the transCommit process() */
 301                         printf("DEBUG -> Recv TRANS_COMMIT \n");
 302                         if((val = transCommitProcess(transinfo, (int)acceptfd)) != 0) {
 303                                 printf("Error in transCommitProcess %s, %d\n", __FILE__, __LINE__);
 304                                 return 1;
 305                         }
 306                         break;
 307
 308                 case TRANS_ABORT_BUT_RETRY_COMMIT_WITH_RELOCATING:
 309                         //TODO expect another transrequest from client
 310                         printf("DEBUG -> Recv TRANS_ABORT_BUT_RETRY_COMMIT_WITH_RELOCATING\n");
 311                         break;
 312                 default:
 313                         printf("No response to TRANS_AGREE OR DISAGREE protocol\n");
 314                         //TODO Use fixed.trans_id  TID since Client may have died
 315                         break;
 316         }
 317         /* Free memory */
 318         printf("DEBUG -> Freeing...\n");
 319         fflush(stdout);
 320         if (transinfo->objmod != NULL) {
 321                 free(transinfo->objmod);
 322                 transinfo->objmod = NULL;
 323         }
 324         if (transinfo->objlocked != NULL) {
 325                 free(transinfo->objlocked);
 326                 transinfo->objlocked = NULL;
 327         }
 328         if (transinfo->objnotfound != NULL) {
 329                 free(transinfo->objnotfound);
 330                 transinfo->objnotfound = NULL;
 331         }
 332         return 0;
 333 }
 334
 335 /* This function increments counters while running a voting decision on all objects involved
 336  * in TRANS_REQUEST */
 337
 338 char handleTransReq(fixed_data_t *fixed, trans_commit_data_t *transinfo, unsigned int *listmid, char *objread, void *modptr, int acceptfd) {
 339         int val, i = 0;
 340         short version;
 341         char control = 0, *ptr;
 342         unsigned int oid;
 343         unsigned int *oidnotfound, *oidlocked, *oidmod;
 344         void *mobj;
 345         objheader_t *headptr;
 346
 347         /* Counters and arrays to formulate decision on control message to be sent */
 348         oidnotfound = (unsigned int *) calloc(fixed->numread + fixed->nummod, sizeof(unsigned int));
 349         oidlocked = (unsigned int *) calloc(fixed->numread + fixed->nummod, sizeof(unsigned int));
 350         oidmod = (unsigned int *) calloc(fixed->nummod, sizeof(unsigned int));
 351         int objnotfound = 0, objlocked = 0, objmod =0, v_nomatch = 0, v_matchlock = 0, v_matchnolock = 0;
 352         int objmodnotfound = 0, nummodfound = 0;
 353
 354         /* modptr points to the beginning of the object store
 355          * created at the Pariticipant.
 356          * Object store holds the modified objects involved in the transaction request */
 357         ptr = modptr;
 358
 359         /* Process each oid in the machine pile/ group per thread */
 360         for (i = 0; i < fixed->numread + fixed->nummod; i++) {
 361                 if (i < fixed->numread) {//Objs only read and not modified
 362                         int incr = sizeof(unsigned int) + sizeof(short);// Offset that points to next position in the objread array
 363                         incr *= i;
 364                         oid = *((unsigned int *)(objread + incr));
 365                         incr += sizeof(unsigned int);
 366                         version = *((short *)(objread + incr));
 367                 } else {//Objs modified
 368                         headptr = (objheader_t *) ptr;
 369                         oid = headptr->oid;
 370                         oidmod[objmod] = oid;//Array containing modified oids
 371                         objmod++;
 372                         version = headptr->version;
 373                         ptr += sizeof(objheader_t) + classsize[headptr->type];
 374                 }
 375
 376                 /* Check if object is still present in the machine since the beginning of TRANS_REQUEST */
 377
 378                 if ((mobj = mhashSearch(oid)) == NULL) {/* Obj not found */
 379                         /* Save the oids not found and number of oids not found for later use */
 380                         //oidnotfound[objnotfound] = ((objheader_t *)mobj)->oid;
 381                         oidnotfound[objnotfound] = oid;
 382                         objnotfound++;
 383                 } else { /* If Obj found in machine (i.e. has not moved) */
 384                         /* Check if Obj is locked by any previous transaction */
 385                         if ((((objheader_t *)mobj)->status & LOCK) == LOCK) {
 386                                 if (version == ((objheader_t *)mobj)->version) {      /* If not locked then match versions */
 387                                         v_matchlock++;
 388                                 } else {/* If versions don't match ...HARD ABORT */
 389                                         v_nomatch++;
 390                                         /* Send TRANS_DISAGREE to Coordinator */
 391                                         control = TRANS_DISAGREE;
 392                                         if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
 393                                                 perror("Error in sending control to the Coordinator\n");
 394                                                 return 0;
 395                                         }
 396                                         printf("DEBUG -> Sending TRANS_DISAGREE\n");
 397                                         return control;
 398                                 }
 399                         } else {/* If Obj is not locked then lock object */
 400                                 ((objheader_t *)mobj)->status |= LOCK;
 401
 402                                 /*TESTING Add random wait to make transactions run for a long time such that
 403                                  * we can test for soft abort case */
 404
 405                                 randomdelay();
 406
 407                                 /* Save all object oids that are locked on this machine during this transaction request call */
 408                                 oidlocked[objlocked] = ((objheader_t *)mobj)->oid;
 409                                 objlocked++;
 410                                 if (version == ((objheader_t *)mobj)->version) { /* Check if versions match */
 411                                         v_matchnolock++;
 412                                 } else { /* If versions don't match ...HARD ABORT */
 413                                         v_nomatch++;
 414                                         control = TRANS_DISAGREE;
 415                                         /* Send TRANS_DISAGREE to Coordinator */
 416                                         if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
 417                                                 perror("Error in sending control to the Coordinator\n");
 418                                                 return 0;
 419                                         }
 420                                         printf("DEBUG -> Sending TRANS_DISAGREE\n");
 421                                         return control;
 422                                 }
 423                         }
 424                 }
 425         }
 426
 427         /* Decide what control message to send to Coordinator */
 428         if ((val = decideCtrlMessage(fixed, transinfo, &v_matchnolock, &v_matchlock, &v_nomatch, &objnotfound, &objlocked,
 429                                         modptr, oidnotfound, oidlocked, oidmod, acceptfd)) == 0) {
 430                 printf("Error in decideCtrlMessage %s, %d\n", __FILE__, __LINE__);
 431                 return 0;
 432         }
 433
 434         return val;
 435
 436 }
 437 /* This function decides what control message such as TRANS_AGREE, TRANS_DISAGREE or TRANS_SOFT_ABORT
 438  * to send to Coordinator based on the votes of oids involved in the transaction */
 439 int decideCtrlMessage(fixed_data_t *fixed, trans_commit_data_t *transinfo, int *v_matchnolock, int *v_matchlock,
 440                 int *v_nomatch, int *objnotfound, int *objlocked, void *modptr,
 441                 unsigned int *oidnotfound, unsigned int *oidlocked, unsigned int *oidmod,
 442                 int acceptfd) {
 443         int val;
 444         char control = 0;
 445         /* Condition to send TRANS_AGREE */
 446         if(*(v_matchnolock) == fixed->numread + fixed->nummod) {
 447                 control = TRANS_AGREE;
 448                 if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
 449                         perror("Error in sending control to Coordinator\n");
 450                         return 0;
 451                 }
 452                 printf("DEBUG -> Sending TRANS_AGREE\n");
 453         }
 454         /* Condition to send TRANS_SOFT_ABORT */
 455         if((*(v_matchlock) > 0 && *(v_nomatch) == 0) || (*(objnotfound) > 0 && *(v_nomatch) == 0)) {
 456                 control = TRANS_SOFT_ABORT;
 457                 char msg[]={TRANS_SOFT_ABORT, 0,0,0,0};
 458                 *((int*)&msg[1])= *(objnotfound);
 459
 460                 printf("DEBUG -> Sending TRANS_SOFT_ABORT\n");
 461                 /* Send control message */
 462                 if((val = send(acceptfd, &msg, sizeof(msg),MSG_NOSIGNAL)) < sizeof(msg)) {
 463                         perror("Error in sending no of objects that are not found\n");
 464                         return 0;
 465                 }
 466                 /* Send number of oids not found and the missing oids if objects are missing in the machine */
 467                 if(*(objnotfound) != 0) {
 468                         int size = sizeof(unsigned int)* *(objnotfound);
 469                         if((val = send(acceptfd, oidnotfound, size ,MSG_NOSIGNAL)) < size) {
 470                                 perror("Error in sending objects that are not found\n");
 471                                 return 0;
 472                         }
 473                 }
 474         }
 475
 476         /* Fill out the trans_commit_data_t data structure. This is required for a trans commit process
 477          * if Participant receives a TRANS_COMMIT */
 478         transinfo->objmod = oidmod;
 479         transinfo->objlocked = oidlocked;
 480         transinfo->objnotfound = oidnotfound;
 481         transinfo->modptr = modptr;
 482         transinfo->nummod = fixed->nummod;
 483         transinfo->numlocked = *(objlocked);
 484         transinfo->numnotfound = *(objnotfound);
 485
 486         return control;
 487 }
 488
 489 /* This function processes all modified objects involved in a TRANS_COMMIT and updates pointer
 490  * addresses in lookup table and also changes version number
 491  * Sends an ACK back to Coordinator */
 492 int transCommitProcess(trans_commit_data_t *transinfo, int acceptfd) {
 493         objheader_t *header;
 494         int i = 0, offset = 0;
 495         char control;
 496         /* Process each modified object saved in the mainobject store */
 497         for(i=0; i<transinfo->nummod; i++) {
 498                 if((header = (objheader_t *) mhashSearch(transinfo->objmod[i])) == NULL) {
 499                         printf("mhashsearch returns NULL at %s, %d\n", __FILE__, __LINE__);
 500                 }
 501                 /* Change reference count of older address and free space in objstr ?? */
 502                 header->rcount = 1; //Not sure what would be the val
 503
 504                 /* Change ptr address in mhash table */
 505                 printf("DEBUG -> removing object oid = %d\n", transinfo->objmod[i]);
 506                 mhashRemove(transinfo->objmod[i]);
 507                 mhashInsert(transinfo->objmod[i], (transinfo->modptr + offset));
 508                 offset += sizeof(objheader_t) + classsize[header->type];
 509
 510                 /* Update object version number */
 511                 header = (objheader_t *) mhashSearch(transinfo->objmod[i]);
 512                 header->version += 1;
 513         }
 514         /* Unlock locked objects */
 515         for(i=0; i<transinfo->numlocked; i++) {
 516                 header = (objheader_t *) mhashSearch(transinfo->objlocked[i]);
 517                 header->status &= ~(LOCK);
 518         }
 519
 520         //TODO Update location lookup table
 521
 522         /* Send ack to coordinator */
 523         control = TRANS_SUCESSFUL;
 524         printf("DEBUG-> TRANS_SUCESSFUL\n");
 525         if(send((int)acceptfd, &control, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
 526                 perror("Error sending ACK to coordinator\n");
 527         }
 528
 529         return 0;
 530 }
 531
 532 int prefetchReq(int acceptfd) {
 533         int i, length, sum, n, numbytes, numoffset, N, objnotfound = 0, size, count = 0;
 534         unsigned int oid, index = 0;
 535         char *ptr, buffer[PRE_BUF_SIZE];
 536         void *mobj;
 537         unsigned int objoid;
 538         char *header, control;
 539         objheader_t * head;
 540
 541         /* Repeatedly recv the oid and offset pairs sent for prefetch */
 542         while(numbytes = recv((int)acceptfd, &length, sizeof(int), 0) != 0) {
 543                 count++;
 544                 if(length == -1)
 545                         break;
 546                 sum = 0;
 547                 index = sizeof(unsigned int); // Index starts with sizeof  unsigned int because the
 548                                               // first 4 bytes are saved to send the
 549                                               // size of the buffer (that is computed at the end of the loop)
 550                 oid = recv((int)acceptfd, &oid, sizeof(unsigned int), 0);
 551                 numoffset = (length - (sizeof(int) + sizeof(unsigned int)))/ sizeof(short);
 552                 N = numoffset * sizeof(short);
 553                 short offset[numoffset];
 554                 ptr = (char *)&offset;
 555                 /* Recv the offset values per oid */
 556                 do {
 557                         n = recv((int)acceptfd, (void *)ptr+sum, N-sum, 0);
 558                         sum += n;
 559                 } while(sum < N && n != 0);
 560
 561                 /* Process each oid */
 562                 /* Check if object is still present in the machine since the beginning of TRANS_PREFETCH */
 563                 if ((mobj = mhashSearch(oid)) == NULL) {/* Obj not found */
 564                         /* Save the oids not found in buffer for later use */
 565                         *(buffer + index) = OBJECT_NOT_FOUND;
 566                         index += sizeof(char);
 567                         memcpy(buffer+index, &oid, sizeof(unsigned int));
 568                         index += sizeof(unsigned int);
 569                 } else { /* If Obj found in machine (i.e. has not moved) */
 570                         /* send the oid, it's size, it's header and data */
 571                         header = (char *) mobj;
 572                         head = (objheader_t *) header;
 573                         size = sizeof(objheader_t) + sizeof(classsize[head->type]);
 574                         *(buffer + index) = OBJECT_FOUND;
 575                         index += sizeof(char);
 576                         memcpy(buffer+index, &oid, sizeof(unsigned int));
 577                         index += sizeof(unsigned int);
 578                         memcpy(buffer+index, &size, sizeof(int));
 579                         index += sizeof(int);
 580                         memcpy(buffer + index, header, size);
 581                         index += size;
 582                         /* Calculate the oid corresponding to the offset value */
 583                         for(i = 0 ; i< numoffset ; i++) {
 584                                 objoid = *((int *)(header + sizeof(objheader_t) + offset[i]));
 585                                 if((header = (char *) mhashSearch(objoid)) == NULL) {
 586                                         /* Obj not found, send oid */
 587                                         *(buffer + index) = OBJECT_NOT_FOUND;
 588                                         index += sizeof(char);
 589                                         memcpy(buffer+index, &oid, sizeof(unsigned int));
 590                                         index += sizeof(unsigned int);
 591                                         break;
 592                                 } else {/* Obj Found */
 593                                         /* send the oid, it's size, it's header and data */
 594                                         head = (objheader_t *) header;
 595                                         size = sizeof(objheader_t) + sizeof(classsize[head->type]);
 596                                         *(buffer + index) = OBJECT_FOUND;
 597                                         index += sizeof(char);
 598                                         memcpy(buffer+index, &oid, sizeof(unsigned int));
 599                                         index += sizeof(unsigned int);
 600                                         memcpy(buffer+index, &size, sizeof(int));
 601                                         index += sizeof(int);
 602                                         memcpy(buffer + index, header, size);
 603                                         index += size;
 604                                         continue;
 605                                 }
 606                         }
 607                 }
 608                 /* Check for overflow in the buffer */
 609                 if (index >= PRE_BUF_SIZE) {
 610                         printf("Char buffer is overflowing\n");
 611                         return 1;
 612                 }
 613                 /* Send Prefetch response control message only once*/
 614                 if(count == 1) {
 615                         control = TRANS_PREFETCH_RESPONSE;
 616                         if((numbytes = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
 617                                 perror("Error in sending PREFETCH RESPONSE to Coordinator\n");
 618                                 return 1;
 619                         }
 620                 }
 621
 622                 /* Add the buffer size into buffer as a parameter */
 623                 memcpy(buffer, &index, sizeof(unsigned int));
 624                 /* Send the entire buffer with its size and oids found and not found */
 625                 if(send((int)acceptfd, &buffer, sizeof(index - 1), MSG_NOSIGNAL) < sizeof(index -1)) {
 626                         perror("Error sending oids found\n");
 627                         return 1;
 628                 }
 629         }
 630         return 0;
 631 }