src/storage/ChunkIterator.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
  22 //No iterators for variable size allocators
  23 ChunkIterator Chunk::getIterator()
  24 {
  25     ChunkIterator iter;
  26     iter.chunkID_ = chunkID_;
  27     iter.allocSize_ = allocSize_;
  28     iter.allocType_ = allocType_;
  29     iter.iterPage_ = firstPage_;
  30     iter.nodeOffset_ = 0;
  31     iter.noOfNodes_ = os::floor((PAGE_SIZE - sizeof(PageInfo)) / allocSize_);
  32     return iter;
  33 }
  34
  35 void* ChunkIterator::nextElement()
  36 {
  37     if(NULL == iterPage_)
  38     {
  39         printError(ErrNotExists,"No iter page exists.");
  40         return NULL;
  41     }
  42     //No iterators for variable size allocators
  43     if(0 == allocSize_)
  44     {
  45         printError(ErrNotExists,"Iterators are not for variable size allocators");
  46         return NULL;
  47     }
  48     PageInfo* pageInfo = (PageInfo*)iterPage_;
  49     if (0 == noOfNodes_)
  50     {
  51         //means tuple larger than PAGE_SIZE
  52         iterPage_ = pageInfo->nextPage_;
  53         return (char*)pageInfo + sizeof(PageInfo)+ sizeof(int);
  54     }
  55
  56     char *data = ((char*)iterPage_) + sizeof(PageInfo) + (nodeOffset_ * allocSize_) ;
  57
  58     //check whether there are any nodes in the current page
  59     int i = nodeOffset_;
  60     while(nodeOffset_ < noOfNodes_)
  61     {
  62         if (*((int*)data) == 0)
  63         {
  64           //not used, so skip it
  65            data = data + allocSize_;
  66            nodeOffset_++;
  67            if (data >= (char*)iterPage_ + PAGE_SIZE) break;
  68         }
  69         else
  70         {
  71            //used, return element pointer
  72            nodeOffset_++;
  73            printDebug(DM_Iterator,"ChunkID:%d Returning %x nodeOffset:%d",
  74                                   chunkID_, data + sizeof(int), nodeOffset_);
  75            return data + sizeof(int);
  76         }
  77     }
  78     //go to next page and check till it exhausts
  79     while(pageInfo->nextPage_ != NULL)
  80     {
  81         iterPage_ = pageInfo->nextPage_;
  82         pageInfo = ((PageInfo*)iterPage_);
  83         data = (char*)iterPage_ + sizeof(PageInfo);
  84         nodeOffset_ = 0;
  85         while(nodeOffset_ < noOfNodes_)
  86         {
  87             if (*((int*)data) == 0)
  88             {
  89                //not used, so skip it
  90                data = data + allocSize_;
  91                nodeOffset_++;
  92             }
  93             else
  94             {
  95                 nodeOffset_++;
  96                 printDebug(DM_Iterator,"ChunkID:%d Returning %x Page:%x nodeOffset:%d",
  97                                  chunkID_, data + sizeof(int), pageInfo, nodeOffset_);
  98                 return data +sizeof(int);
  99             }
 100         }
 101     }
 102     return NULL;
 103 }