src/server/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     db->releaseAllocDatabaseMutex();
  84     return data + sizeof(int);
  85
  86 }
  87
  88 void* Chunk::allocateFromFirstPage(Database *db, int noOfDataNodes)
  89 {
  90     PageInfo *pageIter = ((PageInfo*)firstPage_);
  91     printDebug(DM_Alloc, "Chunk ID:%d. No free page in database",
  92                                                        chunkID_);
  93     printDebug(DM_Alloc, "Scan from firstPage:%x for free nodes",
  94                                                      firstPage_);
  95     char *data = NULL;
  96     int i = 0;
  97     //scan from first page to locate a free node available
  98     while(NULL != pageIter)
  99     {
 100         data = ((char*)pageIter) + sizeof(PageInfo);
 101         if (pageIter->hasFreeSpace_ == 1)
 102         {
 103             for (i = 0; i< noOfDataNodes -1; i++)
 104             {
 105                 if (1 == *((int*)data))
 106                     data = data + allocSize_;
 107                 else break;
 108             }
 109             if (i != noOfDataNodes -1) break;
 110         }
 111         printDebug(DM_Alloc, "Chunk ID: %d Page :%x does not have free nodes",
 112                                                            chunkID_, pageIter);
 113         pageIter = (PageInfo*)((PageInfo*) pageIter)->nextPage_;
 114     }
 115     if (NULL == pageIter) return NULL;
 116     printDebug(DM_Alloc,"ChunkID:%d Scan for free node End:Page :%x",
 117                                                   chunkID_, pageIter);
 118     *((int*)data) = 1;
 119     return data + sizeof(int);
 120
 121 }
 122
 123 void* Chunk::allocateFromNewPage(Database *db)
 124 {
 125     DbRetVal ret = db->getAllocDatabaseMutex();
 126     if (ret != 0)
 127     {
 128         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 129         return NULL;
 130     }
 131     //get a new page from db
 132     Page *page = db->getFreePage();
 133     if (page == NULL)
 134     {
 135         db->releaseAllocDatabaseMutex();
 136         return NULL;
 137     }
 138     printDebug(DM_Alloc, "ChunkID:%d Normal Data Item newPage:%x",
 139                                                   chunkID_, page);
 140     //Initialize pageInfo for this new page
 141     PageInfo *pInfo = (PageInfo*)page;
 142     pInfo->setPageAsUsed(0);
 143
 144     //create the link between old page and the newly created page
 145     PageInfo* pageInfo = ((PageInfo*)curPage_);
 146     pageInfo->nextPage_ = page;
 147
 148     //make this new page as the current page
 149     curPage_ = page;
 150
 151     char* data = ((char*)page) + sizeof(PageInfo);
 152     *((int*)data) = 1;
 153     db->releaseAllocDatabaseMutex();
 154     return data + sizeof(int);
 155 }
 156
 157 //Allocates memory to store data
 158 //TODO::check whether it is locked before allocating.
 159 //delete tuple will set the usedflag to true, but locks will be held
 160 //till commit and it shall be rolledback.So make sure that it does not
 161 //allocate deleted tuple which is yet to be commited.
 162
 163 void* Chunk::allocate(Database *db, DbRetVal *status)
 164 {
 165     PageInfo* pageInfo = ((PageInfo*)curPage_);
 166
 167     int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 168     char *data = ((char*)curPage_) + sizeof(PageInfo);
 169     printDebug(DM_Alloc, "Chunk::allocate id:%d curPage:%x noOfDataNodes:%d",
 170                          chunkID_, curPage_, noOfDataNodes);
 171
 172     //1.scan through data list and find if any is free to use in current page
 173     //2.If there is none then
 174     //    a) get new free page from db. set the prev->next to point
 175     //       to this new page
 176     //4.  b) initialize the free page to zero and get first data ptr.
 177     //5.If there is one, return that
 178
 179     //For allocation more than PAGE_SIZE
 180     if (0 == noOfDataNodes)
 181     {
 182         data = (char*) allocateForLargeDataSize(db);
 183         return data;
 184     }
 185
 186     int ret = getChunkMutex(db->procSlot);
 187     if (ret != 0)
 188     {
 189         if (status != NULL) *status = ErrLockTimeOut;
 190         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 191         return NULL;
 192     }
 193     int i = noOfDataNodes;
 194     if (pageInfo->hasFreeSpace_ == 1)
 195     {
 196         for (i = 1; i< noOfDataNodes; i++)
 197         {
 198             if (*((int*)data) == 1) data = data + allocSize_;
 199             else break;
 200         }
 201
 202     }
 203     printDebug(DM_Alloc, "ChunkID:%d Node which might be free is %d",
 204                                                         chunkID_, i);
 205     //It comes here if the pageInfo->hasFreeSpace ==0
 206     //or there are no free data space in this page
 207     if (i == noOfDataNodes && *((int*)data) == 1)
 208     {
 209
 210         printDebug(DM_Alloc, "ChunkID:%d curPage does not have free nodes.", chunkID_);
 211         //there are no free data space in this page
 212         pageInfo->hasFreeSpace_ = 0;
 213         if (chunkID_ == LockTableId || chunkID_ == TransHasTableId)
 214         {
 215            data = (char*) allocateFromFirstPage(db, noOfDataNodes);
 216            if (NULL == data)
 217            {
 218               data = (char*) allocateFromNewPage(db);
 219               if (data == NULL)
 220               {
 221                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 222                 if (status != NULL) *status = ErrNoMemory;
 223               }
 224            }
 225         }
 226         else
 227         {
 228            data = (char*) allocateFromNewPage(db);
 229            if (NULL == data)
 230            {
 231               data = (char*) allocateFromFirstPage(db, noOfDataNodes);
 232               if (data == NULL)
 233               {
 234                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 235                 if (status != NULL) *status = ErrNoMemory;
 236               }
 237            }
 238         }
 239         releaseChunkMutex(db->procSlot);
 240         return data;
 241     }
 242     *((int*)data) = 1;
 243     releaseChunkMutex(db->procSlot);
 244     return data + sizeof(int);
 245 }
 246
 247
 248 void* Chunk::allocateForLargeDataSize(Database *db, size_t size)
 249 {
 250     //no need to take chunk mutexes for this, as we are taking alloc database mutex
 251     int multiple = os::floor(size / PAGE_SIZE);
 252     int offset = ((multiple + 1) * PAGE_SIZE);
 253     PageInfo* pageInfo = ((PageInfo*)curPage_);
 254     DbRetVal ret = db->getAllocDatabaseMutex();
 255     if (ret != 0)
 256     {
 257         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 258         return NULL;
 259     }
 260     pageInfo = (PageInfo*)db->getFreePage(allocSize_);
 261     if (NULL == pageInfo)
 262     {
 263         db->releaseAllocDatabaseMutex();
 264         printError(ErrNoMemory,"No more free pages in the database:Increase db size");
 265         return NULL;
 266     }
 267     printDebug(DM_VarAlloc,"Chunk::allocate Large Data Item id:%d Size:%d curPage:%x ",
 268                                             chunkID_, size, curPage_);
 269     //TODO:: logic pending
 270
 271
 272     //REDESIGN MAY BE REQUIRED:Lets us live with this for now.
 273     //what happens to the space lets say 10000 bytes is allocated
 274     //it needs 2 pages,= 16000 bytes, 6000 bytes should not be wasted
 275     //in this case.So need to take of this.
 276     //Will be coded at later stage as this is developed to support
 277     //undo logging and currently we shall assume that the logs generated
 278     //wont be greater than PAGE_SIZE.
 279     db->releaseAllocDatabaseMutex();
 280     return NULL;
 281
 282 }
 283
 284
 285
 286 void* Chunk::allocFromNewPageForVarSize(Database *db, size_t size)
 287 {
 288     //Should be called only for data items <PAGE_SIZE
 289     DbRetVal ret = db->getAllocDatabaseMutex();
 290     if (ret != 0)
 291     {
 292         printError(ErrLockTimeOut,"Unable to acquire alloc database Mutex");
 293         return NULL;
 294     }
 295
 296     void *vnode = varSizeFirstFitAllocate(size);
 297     if (vnode != NULL)
 298     {
 299        db->releaseAllocDatabaseMutex();
 300        return vnode;
 301     }
 302
 303     Page *newPage = db->getFreePage();
 304     db->releaseAllocDatabaseMutex();
 305     if (NULL == newPage)
 306     {
 307         return NULL;
 308     }
 309
 310     printDebug(DM_VarAlloc, "ChunkID:%d New Page: %x ", chunkID_, newPage);
 311     PageInfo *pInfo = (PageInfo*) newPage;
 312     pInfo->setPageAsUsed(0);
 313     createDataBucket(newPage, PAGE_SIZE, size);
 314
 315     ((PageInfo*)curPage_)->nextPage_ = newPage;
 316     curPage_ = newPage;
 317     char *data= ((char*)newPage) + sizeof(PageInfo) + sizeof(VarSizeInfo);
 318     return data;
 319 }
 320
 321 //Allocates from the current page of the chunk.
 322 //Scans through the VarSizeInfo objects in the page and gets the free slot
 323 void* Chunk::allocateFromCurPageForVarSize(size_t size)
 324 {
 325     //Should be called only for data items <PAGE_SIZE
 326     Page *page = ((PageInfo*)curPage_);
 327     printDebug(DM_VarAlloc, "Chunk::allocate Normal Data Item id:%d Size:%d curPage:%x ",
 328                                                chunkID_, size, curPage_);
 329     VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) +
 330                                                 sizeof(PageInfo));
 331     while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 332     {
 333         if (0 == varInfo->isUsed_)
 334         {
 335             if( size + sizeof(VarSizeInfo) < varInfo->size_)
 336             {
 337                 splitDataBucket(varInfo, size);
 338                 printDebug(DM_VarAlloc, "Chunkid:%d splitDataBucket: Size: %d Item:%x ",
 339                                                          chunkID_, size, varInfo);
 340                 return (char*)varInfo + sizeof(VarSizeInfo);
 341             }
 342             else if (size == varInfo->size_) {
 343                 varInfo->isUsed_ = 1;
 344                 return (char *) varInfo + sizeof(VarSizeInfo);
 345             }
 346
 347         }
 348         varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 349                                     +varInfo->size_);
 350     }
 351     return NULL;
 352 }
 353
 354 //Allocates memory to store data of variable size
 355 void* Chunk::allocate(Database *db, size_t size, DbRetVal *status)
 356 {
 357     if (0 == size) return NULL;
 358     //check if the size is more than PAGE_SIZE
 359     //if it is more than the PAGE_SIZE, then allocate new
 360     //page using database and then link the curPage to the
 361     //newly allocated page
 362     //if it is less than PAGE_SIZE, then check the curpage for
 363     //free memory of specified size
 364     //if not available, then scan from the firstPage for the free
 365     //space
 366
 367     //TODO::During the scan, merge nearby nodes if both are free
 368     //if not available then allocate new page
 369
 370     size_t alignedSize = os::align(size);
 371     void *data = NULL;
 372     int ret = getChunkMutex(db->procSlot);
 373     if (ret != 0)
 374     {
 375         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 376         return NULL;
 377     }
 378     if (alignedSize > PAGE_SIZE)
 379     {
 380         data =  allocateForLargeDataSize(db, alignedSize);
 381     }
 382     else
 383     {
 384         data = allocateFromCurPageForVarSize(alignedSize);
 385         if (NULL == data) {
 386             //No available spaces in the current page.
 387             //allocate new page
 388             data= allocFromNewPageForVarSize(db, alignedSize);
 389             if (NULL == data) {
 390                 printError(ErrNoMemory, "No memory in any of the pages:Increase db size");
 391                 if (status != NULL) *status = ErrNoMemory;
 392             }
 393         }
 394     }
 395     releaseChunkMutex(db->procSlot);
 396     return data;
 397 }
 398
 399 //Assumes chunk mutex is already taken, before calling this
 400 void* Chunk::varSizeFirstFitAllocate(size_t size)
 401 {
 402     printDebug(DM_VarAlloc, "Chunk::varSizeFirstFitAllocate size:%d firstPage:%x",
 403                                                size, firstPage_);
 404
 405     Page *page = ((PageInfo*)firstPage_);
 406     size_t alignedSize = os::align(size);
 407     while(NULL != page)
 408     {
 409         VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 410         while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 411         {
 412             if (0 == varInfo->isUsed_)
 413             {
 414                 if( alignedSize < varInfo->size_)
 415                 {
 416                     splitDataBucket(varInfo, alignedSize);
 417                     return ((char*)varInfo) + sizeof(VarSizeInfo);
 418                 }
 419                 else if (alignedSize == varInfo->size_) {
 420                     varInfo->isUsed_ = 1;
 421                     printDebug(DM_VarAlloc, "VarSizeFirstFitAllocate returning %x", ((char*)varInfo) +sizeof(VarSizeInfo));
 422                     return ((char *) varInfo) + sizeof(VarSizeInfo);
 423                 }
 424             }
 425             varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 426                                     +varInfo->size_);
 427         }
 428         printDebug(DM_VarAlloc, "Chunk:This page does not have free data nodes page:%x", page);
 429         page = ((PageInfo*) page)->nextPage_;
 430     }
 431     return NULL;
 432 }
 433
 434 void Chunk::freeForVarSizeAllocator(void *ptr, int pslot)
 435 {
 436     int ret = getChunkMutex(pslot);
 437     if (ret != 0)
 438     {
 439         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 440         return;
 441     }
 442     VarSizeInfo *varInfo = (VarSizeInfo*)((char*)ptr- sizeof(VarSizeInfo));
 443     varInfo->isUsed_ = 0;
 444     printDebug(DM_VarAlloc,"chunkID:%d Unset isUsed for %x", chunkID_, varInfo);
 445     releaseChunkMutex(pslot);
 446     return;
 447
 448 }
 449
 450 void Chunk::freeForLargeAllocator(void *ptr, int pslot)
 451 {
 452     //There will be max only one data element in a page.
 453     //PageInfo is stored just before the data.
 454     int ret = getChunkMutex(pslot);
 455     if (ret != 0)
 456     {
 457         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 458         return;
 459     }
 460     PageInfo *pageInfo = (PageInfo*)(((char*)
 461                          ptr) - (sizeof(PageInfo) + sizeof(int)));
 462     PageInfo *pInfo = (PageInfo*)firstPage_, *prev = (PageInfo*)firstPage_;
 463     bool found = false;
 464     while(!found)
 465     {
 466         if (pInfo == pageInfo) {found = true;  break; }
 467         prev = pInfo;
 468         pInfo = (PageInfo*)pInfo->nextPage_;
 469     }
 470     if (!found)
 471     {
 472         printError(ErrSysFatal,"Page %x not found in page list:Logical error", pageInfo );
 473         releaseChunkMutex(pslot);
 474         return ;
 475     }
 476     prev->nextPage_ = pageInfo->nextPage_;
 477     pageInfo->nextPageAfterMerge_ = NULL;
 478     pageInfo->isUsed_ = 0;
 479     os::memset(pageInfo,  0 , allocSize_);
 480     pageInfo->hasFreeSpace_ = 1;
 481     releaseChunkMutex(pslot);
 482     return;
 483 }
 484
 485 //Frees the memory pointed by ptr
 486 void Chunk::free(Database *db, void *ptr)
 487 {
 488     if (0 == allocSize_)
 489     {
 490         freeForVarSizeAllocator(ptr, db->procSlot);
 491         return;
 492     }
 493     int noOfDataNodes =os::floor((PAGE_SIZE - sizeof(PageInfo)) / allocSize_);
 494
 495     if (0 == noOfDataNodes)
 496     {
 497         freeForLargeAllocator(ptr, db->procSlot);
 498         return;
 499     }
 500     int ret = getChunkMutex(db->procSlot);
 501     if (ret != 0)
 502     {
 503         printError(ErrLockTimeOut,"Unable to acquire chunk Mutex");
 504         return;
 505     }
 506      //below is the code for freeing in fixed size allocator
 507
 508      //unset the used flag
 509     *((int*)ptr -1 ) = 0;
 510     PageInfo *pageInfo;
 511     pageInfo = getPageInfo(db, ptr);
 512     if (NULL == pageInfo)
 513     {
 514         printError(ErrSysFatal,"Probable Data corruption: pageInfo is NULL", pageInfo );
 515         releaseChunkMutex(db->procSlot);
 516         return;
 517     }
 518     //set the pageinfo where this ptr points
 519     pageInfo->hasFreeSpace_ = 1;
 520     releaseChunkMutex(db->procSlot);
 521     return;
 522 }
 523
 524 //returns the pageInfo of the page where this ptr points
 525 //This works only if the data size is less than PAGE_SIZE
 526 //If ptr points to data which is more than PAGE_SIZE,then
 527 //calling this might lead to memory corruption
 528 //Note:IMPORTANT::assumes db lock is taken before calling this
 529 PageInfo* Chunk::getPageInfo(Database *db, void *ptr)
 530 {
 531     if (allocSize_ < PAGE_SIZE - sizeof(PageInfo)) {
 532        int rem = (long) ptr % 8192;
 533        return (PageInfo*)(((char*)ptr) - rem);
 534     } else {
 535         //large size allocator
 536         char *inPtr = (char*)ptr;
 537         PageInfo* pageInfo = ((PageInfo*)firstPage_);
 538
 539         while( pageInfo != NULL )
 540         {
 541           if (inPtr > (char*) pageInfo && pageInfo->nextPageAfterMerge_ >inPtr)
 542             return pageInfo;
 543         pageInfo = (PageInfo*)pageInfo->nextPage_ ;
 544         }
 545     }
 546     return NULL;
 547 }
 548
 549 //If called on chunk used to store tuples, it returns the total number of rows
 550 //present in the table
 551 long Chunk::getTotalDataNodes()
 552 {
 553     long totalNodes =0;
 554     if (0 == allocSize_) //->variable size allocator
 555     {
 556         Page *page = ((PageInfo*)firstPage_);
 557         while(NULL != page)
 558         {
 559             VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 560             while ((char*) varInfo < ((char*)page + PAGE_SIZE))
 561             {
 562                 if (1 == varInfo->isUsed_) totalNodes++;
 563                 varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 564                                     +varInfo->size_);
 565             }
 566             page = ((PageInfo*) page)->nextPage_;
 567         }
 568         return totalNodes;
 569     }
 570
 571     //TODO::for large size allocator
 572     if (allocSize_ >PAGE_SIZE)//->each page has only one data node
 573         return 0;
 574
 575     int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 576     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 577     char *data = ((char*)firstPage_) + sizeof(PageInfo);
 578     int i=0;
 579     while( pageInfo != NULL )
 580     {
 581         data = ((char*)pageInfo) + sizeof(PageInfo);
 582         for (i = 0; i< noOfDataNodes; i++)
 583         {
 584             if (*((int*)data) == 1) { totalNodes++;}
 585             data = data + allocSize_;
 586         }
 587         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 588     }
 589     return totalNodes;
 590 }
 591
 592 //TODO::for other type of allocators
 593 int Chunk::compact()
 594 {
 595     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 596     PageInfo* prevPage = pageInfo;
 597     if (NULL == pageInfo)
 598     {
 599         return 0;
 600     }
 601     pageInfo = (PageInfo*)pageInfo->nextPage_;
 602     if (0 == allocSize_)
 603     {
 604       while( pageInfo != NULL )
 605       {
 606         bool flag = false;
 607         VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)pageInfo) +
 608                                             sizeof(PageInfo));
 609         while ((char*) varInfo < ((char*)pageInfo + PAGE_SIZE))
 610         {
 611             if (1 == varInfo->isUsed_) {flag=true; break;}
 612             varInfo = (VarSizeInfo*)((char*)varInfo + sizeof(VarSizeInfo)
 613                                    +varInfo->size_);
 614         }
 615         if (!flag) {
 616             printDebug(DM_VarAlloc,"Freeing unused page in varsize allocator %x\n", pageInfo);
 617             prevPage->nextPage_ = pageInfo->nextPage_;
 618             pageInfo->isUsed_ = 0;
 619         }
 620         prevPage = pageInfo;
 621         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 622         printDebug(DM_VarAlloc,"compact iter %x\n", pageInfo);
 623       }
 624     }else if (allocSize_ < PAGE_SIZE)
 625     {
 626       while( pageInfo != NULL )
 627       {
 628         bool flag = false;
 629         int noOfDataNodes=os::floor((PAGE_SIZE - sizeof(PageInfo))/allocSize_);
 630         char *data = ((char*)pageInfo) + sizeof(PageInfo);
 631         for (int i = 0; i< noOfDataNodes -1; i++)
 632         {
 633             if (1 == *((int*)data)) { flag = true; break; }
 634             data = data +allocSize_;
 635         }
 636         if (!flag) {
 637             printDebug(DM_Alloc,"Freeing unused page in fixed allocator %x\n", pageInfo);
 638             prevPage->nextPage_ = pageInfo->nextPage_;
 639             pageInfo->isUsed_ = 0;
 640         }
 641         prevPage = pageInfo;
 642         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 643         printDebug(DM_Alloc,"compact iter %x\n", pageInfo);
 644       }
 645     }
 646     return 0;
 647 }
 648
 649 int Chunk::totalPages()
 650 {
 651     //logic is same for variable size and for large data node allocator.
 652     PageInfo* pageInfo = ((PageInfo*)firstPage_);
 653     int totPages=0;
 654     while( pageInfo != NULL )
 655     {
 656         totPages++;
 657         pageInfo = (PageInfo*)(((PageInfo*)pageInfo)->nextPage_) ;
 658     }
 659     return totPages;
 660 }
 661
 662 int Chunk::initMutex()
 663 {
 664     return chunkMutex_.init("Chunk");
 665 }
 666 int Chunk::getChunkMutex(int procSlot)
 667 {
 668     return chunkMutex_.getLock(procSlot);
 669 }
 670 int Chunk::releaseChunkMutex(int procSlot)
 671 {
 672     return chunkMutex_.releaseLock(procSlot);
 673 }
 674 int Chunk::destroyMutex()
 675 {
 676     return chunkMutex_.destroy();
 677 }
 678 void Chunk::splitDataBucket(VarSizeInfo *varInfo, size_t needSize)
 679 {
 680     int remSpace = varInfo->size_ - sizeof(VarSizeInfo) - needSize;
 681     varInfo->isUsed_ = 1;
 682     varInfo->size_ = needSize;
 683     varInfo = (VarSizeInfo*)((char*)varInfo +
 684                sizeof(VarSizeInfo) +  varInfo->size_);
 685     varInfo->isUsed_ = 0;
 686     varInfo->size_  = remSpace;
 687     return;
 688 }
 689
 690
 691 void Chunk::createDataBucket(Page *page, size_t totalSize, size_t needSize)
 692 {
 693     VarSizeInfo *varInfo = (VarSizeInfo*)(((char*)page) + sizeof(PageInfo));
 694     varInfo->isUsed_ = 0;
 695     varInfo->size_ = PAGE_SIZE - sizeof(PageInfo) - sizeof(VarSizeInfo);
 696     splitDataBucket(varInfo, needSize);
 697     return;
 698 }
 699
 700
 701