src/storage/Chunk.cxx

   1 /***************************************************************************
   2  *   Copyright (C) 2007 by www.databasecache.com                           *
   3  *   Contact: praba_tuty@databasecache.com                                 *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15   ***************************************************************************/
  16 #include<Allocator.h>
  17 #include<Database.h>
  18 #include<os.h>
  19 #include<Debug.h>
  20 #include<Config.h>
  21 #include<CatalogTables.h>
  22
  23 // sets the size of the Chunk allocator for fixed size
  24 // allocator
  25 // we need one integer to store book keeping information
  26 // whether the storage allocation unit is used of not
  27 // when it is deleted this flag is only set to unused
  28 void Chunk::setSize(size_t size)
  29 {
  30
  31     size_t needSize = size + sizeof(int);
  32     size_t multiple = (size_t) os::floor(needSize / sizeof(size_t));
  33     size_t rem = needSize % sizeof(size_t);
  34     if (0 == rem)
  35         allocSize_ = needSize;
  36     else
  37         allocSize_  = (multiple + 1) * sizeof(size_t);
  38 }
  39
  40 void* Chunk::allocateForLargeDataSize(Database *db)
  41 {
  42     PageInfo* pageInfo = ((PageInfo*)curPage_);
  43     DbRetVal ret = db->getAllocDatabaseMutex();
  44     if (ret != 0)
  45     {
  46         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
  47         return NULL;
  48     }
  49
  50     //check whether we have space in curPage
  51     if (pageInfo->hasFreeSpace_ == 1)
  52     {
  53         char *data = ((char*)curPage_) + sizeof(PageInfo);
  54         pageInfo->hasFreeSpace_ =0;
  55         *((int*)data) = 1;
  56         db->releaseAllocDatabaseMutex();
  57         return data + sizeof(int);
  58     }
  59
  60
  61     //no space in curpage , get new page from database
  62     pageInfo = (PageInfo*)db->getFreePage(allocSize_);
  63     if (NULL == pageInfo)
  64     {
  65         db->releaseAllocDatabaseMutex();
  66         printError(ErrNoMemory,"No more free pages in the database");
  67         return NULL;
  68     }
  69     printDebug(DM_Alloc, "Chunk ID:%d Large Data Item newPage:%x",
  70                                        chunkID_, pageInfo);
  71     int multiple = os::floor(allocSize_ / PAGE_SIZE);
  72     int offset = ((multiple + 1) * PAGE_SIZE);
  73
  74     pageInfo->setPageAsUsed(offset);
  75
  76     //create the link
  77    ((PageInfo*)curPage_)->nextPage_ = (Page*) pageInfo;
  78     //Make this as current page
  79     curPage_ = (Page*) pageInfo;
  80     char* data = ((char*)curPage_) + sizeof(PageInfo);
  81     //TODO::check whether it is locked
  82     *((int*)data) = 1;
  83     pageInfo->hasFreeSpace_ =0;
  84     db->releaseAllocDatabaseMutex();
  85     return data + sizeof(int);
  86
  87 }
  88
  89 void* Chunk::allocateFromFirstPage(Database *db, int noOfDataNodes)
  90 {
  91     PageInfo *pageIter = ((PageInfo*)firstPage_);
  92     printDebug(DM_Alloc, "Chunk ID:%d. No free page in database",
  93                                                        chunkID_);
  94     printDebug(DM_Alloc, "Scan from firstPage:%x for free nodes",
  95                                                      firstPage_);
  96     char *data = NULL;
  97     int i = 0;
  98     //scan from first page to locate a free node available
  99     while(NULL != pageIter)
 100     {
 101         data = ((char*)pageIter) + sizeof(PageInfo);
 102         if (pageIter->hasFreeSpace_ == 1)
 103         {
 104             for (i = 0; i< noOfDataNodes -1; i++)
 105             {
 106                 if (1 == *((int*)data))
 107                     data = data + allocSize_;
 108                 else break;
 109             }
 110             if (i != noOfDataNodes -1) break;
 111         }
 112         printDebug(DM_Alloc, "Chunk ID: %d Page :%x does not have free nodes",
 113                                                            chunkID_, pageIter);
 114         pageIter = (PageInfo*)((PageInfo*) pageIter)->nextPage_;
 115     }
 116     if (NULL == pageIter) return NULL;
 117     printDebug(DM_Alloc,"ChunkID:%d Scan for free node End:Page :%x",
 118                                                   chunkID_, pageIter);
 119     *((int*)data) = 1;
 120     return data + sizeof(int);
 121
 122 }
 123
 124 void* Chunk::allocateFromNewPage(Database *db)
 125 {
 126     DbRetVal ret = db->getAllocDatabaseMutex();
 127     if (ret != 0)
 128     {
 129         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 130         return NULL;
 131     }
 132     //get a new page from db
 133     Page *page = db->getFreePage();
 134     if (page == NULL)
 135     {
 136         db->releaseAllocDatabaseMutex();
 137         return NULL;
 138     }
 139     printDebug(DM_Alloc, "ChunkID:%d Normal Data Item newPage:%x",
 140                                                   chunkID_, page);
 141     //Initialize pageInfo for this new page
 142     PageInfo *pInfo = (PageInfo*)page;
 143     pInfo->setPageAsUsed(0);
 144
 145     //create the link between old page and the newly created page
 146     PageInfo* pageInfo = ((PageInfo*)curPage_);
 147     pageInfo->nextPage_ = page;
 148
 149     //make this new page as the current page
 150     curPage_ = page;
 151
 152     char* data = ((char*)page) + sizeof(PageInfo);
 153     *((int*)data) = 1;
 154     db->releaseAllocDatabaseMutex();
 155     return data + sizeof(int);
 156 }
 157
 158 //Allocates memory to store data
 159 //TODO::check whether it is locked before allocating.
 160 //delete tuple will set the usedflag to true, but locks will be held
 161 //till commit and it shall be rolledback.So make sure that it does not
 162 //allocate deleted tuple which is yet to be commited.
 163
 164 void* Chunk::allocate(Database *db, DbRetVal *status)
 165 {
 166     PageInfo* pageInfo = ((PageInfo*)curPage_);
 167
 168     int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 169     char *data = ((char*)curPage_) + sizeof(PageInfo);
 170     printDebug(DM_Alloc, "Chunk::allocate id:%d curPage:%x noOfDataNodes:%d",
 171                          chunkID_, curPage_, noOfDataNodes);
 172
 173     //1.scan through data list and find if any is free to use in current page
 174     //2.If there is none then
 175     //    a) get new free page from db. set the prev->next to point
 176     //       to this new page
 177     //4.  b) initialize the free page to zero and get first data ptr.
 178     //5.If there is one, return that
 179
 180     //For allocation more than PAGE_SIZE
 181     if (0 == noOfDataNodes)
 182     {
 183         data = (char*) allocateForLargeDataSize(db);
 184         return data;
 185     }
 186
 187     int ret = getChunkMutex(db->procSlot);
 188     if (ret != 0)
 189     {
 190         if (status != NULL) *status = ErrLockTimeOut;
 191         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 192         return NULL;
 193     }
 194     int i = noOfDataNodes;
 195     if (pageInfo->hasFreeSpace_ == 1)
 196     {
 197         for (i = 1; i< noOfDataNodes; i++)
 198         {
 199             if (*((int*)data) == 1) data = data + allocSize_;
 200             else break;
 201         }
 202
 203     }
 204     printDebug(DM_Alloc, "ChunkID:%d Node which might be free is %d",
 205                                                         chunkID_, i);
 206     //It comes here if the pageInfo->hasFreeSpace ==0
 207     //or there are no free data space in this page
 208     if (i == noOfDataNodes && *((int*)data) == 1)
 209     {
 210
 211         printDebug(DM_Alloc, "ChunkID:%d curPage does not have free nodes.", chunkID_);
 212         //there are no free data space in this page
 213         pageInfo->hasFreeSpace_ = 0;
 214         if (chunkID_ == LockTableId || chunkID_ == TransHasTableId)
 215         {
 216            data = (char*) allocateFromFirstPage(db, noOfDataNodes);
 217            if (NULL == data)
 218            {
 219               data = (char*) allocateFromNewPage(db);
 220               if (data == NULL)
 221               {
 222                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 223                 if (status != NULL) *status = ErrNoMemory;
 224               }
 225            }
 226         }
 227         else
 228         {
 229            data = (char*) allocateFromNewPage(db);
 230            if (NULL == data)
 231            {
 232               data = (char*) allocateFromFirstPage(db, noOfDataNodes);
 233               if (data == NULL)
 234               {
 235                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 236                 if (status != NULL) *status = ErrNoMemory;
 237               }
 238            }
 239         }
 240         releaseChunkMutex(db->procSlot);
 241         return data;
 242     }
 243     *((int*)data) = 1;
 244     releaseChunkMutex(db->procSlot);
 245     return data + sizeof(int);
 246 }
 247
 248
 249 void* Chunk::allocateForLargeDataSize(Database *db, size_t size)
 250 {
 251     //no need to take chunk mutexes for this, as we are taking alloc database mutex
 252     int multiple = os::floor(size / PAGE_SIZE);
 253     int offset = ((multiple + 1) * PAGE_SIZE);
 254     PageInfo* pageInfo = ((PageInfo*)curPage_);
 255     DbRetVal ret = db->getAllocDatabaseMutex();
 256     if (ret != 0)
 257     {
 258         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 259         return NULL;
 260     }
 261     pageInfo = (PageInfo*)db->getFreePage(allocSize_);
 262     if (NULL == pageInfo)
 263     {
 264         db->releaseAllocDatabaseMutex();
 265         printError(ErrNoMemory,"No more free pages in the database:Increase db size");
 266         return NULL;
 267     }
 268     printDebug(DM_VarAlloc,"Chunk::allocate Large Data Item id:%d Size:%d curPage:%x ",
 269                                             chunkID_, size, curPage_);
 270     //TODO:: logic pending
 271
 272
 273     //REDESIGN MAY BE REQUIRED:Lets us live with this for now.
 274     //what happens to the space lets say 10000 bytes is allocated
 275     //it needs 2 pages,= 16000 bytes, 6000 bytes should not be wasted
 276     //in this case.So need to take of this.
 277     //Will be coded at later stage as this is developed to support
 278     //undo logging and currently we shall assume that the logs generated
 279     //wont be greater than PAGE_SIZE.
 280     db->releaseAllocDatabaseMutex();
 281     return NULL;
 282
 283 }
 284
 285
 286
 287 void* Chunk::allocFromNewPageForVarSize(Database *db, size_t size)
 288 {
 289     //Should be called only for data items <PAGE_SIZE
 290     DbRetVal ret = db->getAllocDatabaseMutex();
 291     if (ret != 0)
 292     {
 293         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 294         return NULL;
 295     }
 296
 297     void *vnode = varSizeFirstFitAllocate(size);
 298     if (vnode != NULL)
 299     {
 300        db->releaseAllocDatabaseMutex();
 301        return vnode;
 302     }
 303
 304     Page *newPage = db->getFreePage();
 305     db->releaseAllocDatabaseMutex();
 306     if (NULL == newPage)
 307     {
 308         return NULL;
 309     }
 310
 311     printDebug(DM_VarAlloc, "ChunkID:%d New Page: %x ", chunkID_, newPage);
 312     PageInfo *pInfo = (PageInfo*) newPage;
 313     pInfo->setPageAsUsed(0);
 314     createDataBucket(newPage, PAGE_SIZE, size);
 315
 316     ((PageInfo*)curPage_)->nextPage_ = newPage;
 317     curPage_ = newPage;
 318     char *data= ((char*)newPage) + sizeof(PageInfo) + sizeof(VarSizeInfo);
 319     return data;
 320 }
 321
 322 //Allocates from the current page of the chunk.
 323 //Scans through the VarSizeInfo objects in the page and gets the free slot
 324 void* Chunk::allocateFromCurPageForVarSize(size_t size)
 325 {
 326     //Should be called only for data items <PAGE_SIZE
 327     Page *page = ((PageInfo*)curPage_);
 328     printDebug(DM_VarAlloc, "Chunk::allocate Normal Data Item id:%d Size:%d curPage:%x ",
 329                                                chunkID_, size, curPage_);
 330     VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) +
 331                                                 sizeof(PageInfo));
 332     while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 333     {
 334         if (0 == varInfo->isUsed_)
 335         {
 336             if( size + sizeof(VarSizeInfo) < varInfo->size_)
 337             {
 338                 splitDataBucket(varInfo, size);
 339                 printDebug(DM_VarAlloc, "Chunkid:%d splitDataBucket: Size: %d Item:%x ",
 340                                                          chunkID_, size, varInfo);
 341                 return (char*)varInfo + sizeof(VarSizeInfo);
 342             }
 343             else if (size == varInfo->size_) {
 344                 varInfo->isUsed_ = 1;
 345                 return (char *) varInfo + sizeof(VarSizeInfo);
 346             }
 347
 348         }
 349         varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 350                                     +varInfo->size_);
 351     }
 352     return NULL;
 353 }
 354
 355 //Allocates memory to store data of variable size
 356 void* Chunk::allocate(Database *db, size_t size, DbRetVal *status)
 357 {
 358     if (0 == size) return NULL;
 359     //check if the size is more than PAGE_SIZE
 360     //if it is more than the PAGE_SIZE, then allocate new
 361     //page using database and then link the curPage to the
 362     //newly allocated page
 363     //if it is less than PAGE_SIZE, then check the curpage for
 364     //free memory of specified size
 365     //if not available, then scan from the firstPage for the free
 366     //space
 367
 368     //TODO::During the scan, merge nearby nodes if both are free
 369     //if not available then allocate new page
 370
 371     size_t alignedSize = os::align(size);
 372     void *data = NULL;
 373     int ret = getChunkMutex(db->procSlot);
 374     if (ret != 0)
 375     {
 376         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 377         *status = ErrLockTimeOut;
 378         return NULL;
 379     }
 380     if (alignedSize > PAGE_SIZE)
 381     {
 382         data =  allocateForLargeDataSize(db, alignedSize);
 383     }
 384     else
 385     {
 386         data = allocateFromCurPageForVarSize(alignedSize);
 387         if (NULL == data) {
 388             //No available spaces in the current page.
 389             //allocate new page
 390             data= allocFromNewPageForVarSize(db, alignedSize);
 391             if (NULL == data) {
 392                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 393                 if (status != NULL) *status = ErrNoMemory;
 394             }
 395         }
 396     }
 397     releaseChunkMutex(db->procSlot);
 398     return data;
 399 }
 400
 401 //Assumes chunk mutex is already taken, before calling this
 402 void* Chunk::varSizeFirstFitAllocate(size_t size)
 403 {
 404     printDebug(DM_VarAlloc, "Chunk::varSizeFirstFitAllocate size:%d firstPage:%x",
 405                                                size, firstPage_);
 406
 407     Page *page = ((PageInfo*)firstPage_);
 408     size_t alignedSize = os::align(size);
 409     while(NULL != page)
 410     {
 411         VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 412         while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 413         {
 414             if (0 == varInfo->isUsed_)
 415             {
 416                 if( alignedSize +sizeof(VarSizeInfo) < varInfo->size_)
 417                 {
 418                     splitDataBucket(varInfo, alignedSize);
 419                     return ((char*)varInfo) + sizeof(VarSizeInfo);
 420                 }
 421                 else if (alignedSize == varInfo->size_) {
 422                     varInfo->isUsed_ = 1;
 423                     printDebug(DM_VarAlloc, "VarSizeFirstFitAllocate returning %x", ((char*)varInfo) +sizeof(VarSizeInfo));
 424                     return ((char *) varInfo) + sizeof(VarSizeInfo);
 425                 }
 426             }
 427             varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 428                                     +varInfo->size_);
 429         }
 430         printDebug(DM_VarAlloc, "Chunk:This page does not have free data nodes page:%x", page);
 431         page = ((PageInfo*) page)->nextPage_;
 432     }
 433     return NULL;
 434 }
 435
 436 void Chunk::freeForVarSizeAllocator(void *ptr, int pslot)
 437 {
 438     int ret = getChunkMutex(pslot);
 439     if (ret != 0)
 440     {
 441         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 442         return;
 443     }
 444     VarSizeInfo *varInfo = (VarSizeInfo*)((char*)ptr- sizeof(VarSizeInfo));
 445     varInfo->isUsed_ = 0;
 446     printDebug(DM_VarAlloc,"chunkID:%d Unset isUsed for %x", chunkID_, varInfo);
 447     releaseChunkMutex(pslot);
 448     return;
 449
 450 }
 451
 452 void Chunk::freeForLargeAllocator(void *ptr, int pslot)
 453 {
 454     //There will be max only one data element in a page.
 455     //PageInfo is stored just before the data.
 456     int ret = getChunkMutex(pslot);
 457     if (ret != 0)
 458     {
 459         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 460         return;
 461     }
 462     PageInfo *pageInfo = (PageInfo*)(((char*)
 463                          ptr) - (sizeof(PageInfo) + sizeof(int)));
 464     PageInfo *pInfo = (PageInfo*)firstPage_, *prev = (PageInfo*)firstPage_;
 465     bool found = false;
 466     while(!found)
 467     {
 468         if (pInfo == pageInfo) {found = true;  break; }
 469         prev = pInfo;
 470         pInfo = (PageInfo*)pInfo->nextPage_;
 471     }
 472     if (!found)
 473     {
 474         printError(ErrSysFatal,"Page %x not found in page list:Logical error", pageInfo );
 475         releaseChunkMutex(pslot);
 476         return ;
 477     }
 478     prev->nextPage_ = pageInfo->nextPage_;
 479     pageInfo->nextPageAfterMerge_ = NULL;
 480     pageInfo->isUsed_ = 0;
 481     os::memset(pageInfo,  0 , allocSize_);
 482     pageInfo->hasFreeSpace_ = 1;
 483     releaseChunkMutex(pslot);
 484     return;
 485 }
 486
 487 //Frees the memory pointed by ptr
 488 void Chunk::free(Database *db, void *ptr)
 489 {
 490     if (0 == allocSize_)
 491     {
 492         freeForVarSizeAllocator(ptr, db->procSlot);
 493         return;
 494     }
 495     int noOfDataNodes =os::floor((PAGE_SIZE - sizeof(PageInfo)) / allocSize_);
 496
 497     if (0 == noOfDataNodes)
 498     {
 499         freeForLargeAllocator(ptr, db->procSlot);
 500         return;
 501     }
 502     int ret = getChunkMutex(db->procSlot);
 503     if (ret != 0)
 504     {
 505         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 506         return;
 507     }
 508      //below is the code for freeing in fixed size allocator
 509
 510      //unset the used flag
 511     *((int*)ptr -1 ) = 0;
 512     PageInfo *pageInfo;
 513     pageInfo = getPageInfo(db, ptr);
 514     if (NULL == pageInfo)
 515     {
 516         printError(ErrSysFatal,"Probable Data corruption: pageInfo is NULL", pageInfo );
 517         releaseChunkMutex(db->procSlot);
 518         return;
 519     }
 520     //set the pageinfo where this ptr points
 521     pageInfo->hasFreeSpace_ = 1;
 522     releaseChunkMutex(db->procSlot);
 523     return;
 524 }
 525
 526 //returns the pageInfo of the page where this ptr points
 527 //This works only if the data size is less than PAGE_SIZE
 528 //If ptr points to data which is more than PAGE_SIZE,then
 529 //calling this might lead to memory corruption
 530 //Note:IMPORTANT::assumes db lock is taken before calling this
 531 PageInfo* Chunk::getPageInfo(Database *db, void *ptr)
 532 {
 533     if (allocSize_ < PAGE_SIZE - sizeof(PageInfo)) {
 534        int rem = (long) ptr % PAGE_SIZE;
 535        return (PageInfo*)(((char*)ptr) - rem);
 536     } else {
 537         //large size allocator
 538         char *inPtr = (char*)ptr;
 539         PageInfo* pageInfo = ((PageInfo*)firstPage_);
 540
 541         while( pageInfo != NULL )
 542         {
 543           if (inPtr > (char*) pageInfo && pageInfo->nextPageAfterMerge_ >inPtr)
 544             return pageInfo;
 545         pageInfo = (PageInfo*)pageInfo->nextPage_ ;
 546         }
 547     }
 548     return NULL;
 549 }
 550
 551 //If called on chunk used to store tuples, it returns the total number of rows
 552 //present in the table
 553 long Chunk::getTotalDataNodes()
 554 {
 555     long totalNodes =0;
 556     if (0 == allocSize_) //->variable size allocator
 557     {
 558         Page *page = ((PageInfo*)firstPage_);
 559         while(NULL != page)
 560         {
 561             VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 562             while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 563             {
 564                 if (1 == varInfo->isUsed_) totalNodes++;
 565                 varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 566                                     +varInfo->size_);
 567             }
 568             page = ((PageInfo*) page)->nextPage_;
 569         }
 570         return totalNodes;
 571     }
 572
 573     //TODO::for large size allocator
 574     if (allocSize_ >PAGE_SIZE)//->each page has only one data node
 575     {
 576         Page *page = ((PageInfo*)firstPage_);
 577         while(NULL != page)
 578         {
 579                 //current it page wise  later this will done
 580                 if(1==*(int*)(((char*)page)+sizeof(PageInfo)))
 581                         totalNodes++;
 582                 page = ((PageInfo*) page)->nextPage_;
 583         }
 584         return totalNodes;
 585     }
 586
 587     int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 588     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 589     char *data = ((char*)firstPage_) + sizeof(PageInfo);
 590     int i=0;
 591     while( pageInfo != NULL )
 592     {
 593         data = ((char*)pageInfo) + sizeof(PageInfo);
 594         for (i = 0; i< noOfDataNodes; i++)
 595         {
 596             if (*((int*)data) == 1) { totalNodes++;}
 597             data = data + allocSize_;
 598         }
 599         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 600     }
 601     return totalNodes;
 602 }
 603
 604 //TODO::for other type of allocators
 605 int Chunk::compact()
 606 {
 607     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 608     PageInfo* prevPage = pageInfo;
 609     if (NULL == pageInfo)
 610     {
 611         return 0;
 612     }
 613     pageInfo = (PageInfo*)pageInfo->nextPage_;
 614     if (0 == allocSize_)
 615     {
 616       while( pageInfo != NULL )
 617       {
 618         bool flag = false;
 619         VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)pageInfo) +
 620                                             sizeof(PageInfo));
 621         while ((char*) varInfo < ((char*)pageInfo + PAGE_SIZE))
 622         {
 623             if (1 == varInfo->isUsed_) {flag=true; break;}
 624             varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 625                                    +varInfo->size_);
 626         }
 627         if (!flag) {
 628             printDebug(DM_VarAlloc,"Freeing unused page in varsize allocator %x\n", pageInfo);
 629             prevPage->nextPage_ = pageInfo->nextPage_;
 630             pageInfo->isUsed_ = 0;
 631         }
 632         prevPage = pageInfo;
 633         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 634         printDebug(DM_VarAlloc,"compact iter %x\n", pageInfo);
 635       }
 636     }else if (allocSize_ < PAGE_SIZE)
 637     {
 638       while( pageInfo != NULL )
 639       {
 640         bool flag = false;
 641         int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 642         char *data = ((char*)pageInfo) + sizeof(PageInfo);
 643         for (int i = 0; i< noOfDataNodes -1; i++)
 644         {
 645             if (1 == *((int*)data)) { flag = true; break; }
 646             data = data +allocSize_;
 647         }
 648         if (!flag) {
 649             printDebug(DM_Alloc,"Freeing unused page in fixed allocator %x\n", pageInfo);
 650             prevPage->nextPage_ = pageInfo->nextPage_;
 651             pageInfo->isUsed_ = 0;
 652         }
 653         prevPage = pageInfo;
 654         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 655         printDebug(DM_Alloc,"compact iter %x\n", pageInfo);
 656       }
 657     }
 658     return 0;
 659 }
 660
 661 int Chunk::totalPages()
 662 {
 663     //logic is same for variable size and for large data node allocator.
 664     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 665     int totPages=0;
 666     while( pageInfo != NULL )
 667     {
 668         totPages++;
 669         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 670     }
 671     return totPages;
 672 }
 673
 674 int Chunk::initMutex()
 675 {
 676     return chunkMutex_.init("Chunk");
 677 }
 678 int Chunk::getChunkMutex(int procSlot)
 679 {
 680     return chunkMutex_.getLock(procSlot);
 681 }
 682 int Chunk::releaseChunkMutex(int procSlot)
 683 {
 684     return chunkMutex_.releaseLock(procSlot);
 685 }
 686 int Chunk::destroyMutex()
 687 {
 688     return chunkMutex_.destroy();
 689 }
 690 void Chunk::splitDataBucket(VarSizeInfo *varInfo, size_t needSize)
 691 {
 692     int remSpace = varInfo->size_ - sizeof(VarSizeInfo) - needSize;
 693     varInfo->isUsed_ = 1;
 694     varInfo->size_ = needSize;
 695     varInfo = (VarSizeInfo*)((char*)varInfo +
 696                sizeof(VarSizeInfo) +  varInfo->size_);
 697     varInfo->isUsed_ = 0;
 698     varInfo->size_  = remSpace;
 699     printDebug(DM_VarAlloc, "Remaining space is %d\n", remSpace);
 700     return;
 701 }
 702
 703
 704 void Chunk::createDataBucket(Page *page, size_t totalSize, size_t needSize)
 705 {
 706     VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 707     varInfo->isUsed_ = 0;
 708     varInfo->size_ = PAGE_SIZE - sizeof(PageInfo) - sizeof(VarSizeInfo);
 709     splitDataBucket(varInfo, needSize);
 710     return;
 711 }
 712 void Chunk::setChunkNameForSystemDB(int id)
 713 {
 714                 strcpy(chunkName,ChunkName[id]);
 715 }
 716
 717 void Chunk::print()
 718 {
 719         printf("        <Chunk Id> %d </Chunk Id> \n",chunkID_);
 720         printf("                <TotalPages> %d </TotalPages> \n",totalPages());
 721         printf("                <ChunkName > %s </ChunkName> \n",getChunkName());
 722         printf("                <TotalDataNodes> %d </TotalDataNodes> \n",getTotalDataNodes());
 723         printf("                <SizeOfDataNodes> %d </SizeOfDataNodes> \n",getSize());
 724         printf("                <Allocation Type> ");
 725         if(allocType_==0)
 726         {
 727                 printf("FixedSizeAllocator ");
 728         }else if(allocType_==1)
 729         {
 730                 printf("VariableSizeAllocator ");
 731         }else
 732         {
 733                 printf("UnknownAllocator ");
 734
 735         }
 736         printf("</Allocation Type>\n");
 737 }
 738
 739
 740