release/src/router/mysql/storage/ndb/src/kernel/vm/WOPool.hpp

   1 /* Copyright (c) 2003, 2006, 2007 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 #ifndef WOPOOL_HPP
  17 #define WOPOOL_HPP
  18
  19 #include "Pool.hpp"
  20
  21 struct WOPage
  22 {
  23   STATIC_CONST( WOPAGE_WORDS = GLOBAL_PAGE_SIZE_WORDS - 2 );
  24
  25   Uint32 m_type_id;
  26   Uint32 m_ref_count;
  27   Uint32 m_data[WOPAGE_WORDS];
  28 };
  29
  30 /**
  31  * Write Once Pool
  32  */
  33 struct WOPool
  34 {
  35   Record_info m_record_info;
  36   WOPage* m_memroot;
  37   WOPage* m_current_page;
  38   Pool_context m_ctx;
  39   Uint32 m_current_page_no;
  40   Uint16 m_current_pos;
  41   Uint16 m_current_ref_count;
  42 public:
  43   WOPool();
  44
  45   void init(const Record_info& ri, const Pool_context& pc);
  46   bool seize(Ptr<void>&);
  47   void release(Ptr<void>);
  48   void * getPtr(Uint32 i);
  49
  50 private:
  51   bool seize_new_page(Ptr<void>&);
  52   void release_not_current(Ptr<void>);
  53
  54   void handle_invalid_release(Ptr<void>);
  55   void handle_invalid_get_ptr(Uint32 i);
  56   void handle_inconsistent_release(Ptr<void>);
  57 };
  58
  59 inline
  60 bool
  61 WOPool::seize(Ptr<void>& ptr)
  62 {
  63   Uint32 pos = m_current_pos;
  64   Uint32 size = m_record_info.m_size;
  65   WOPage *pageP = m_current_page;
  66   if (likely(pos + size < WOPage::WOPAGE_WORDS))
  67   {
  68     ptr.i = (m_current_page_no << POOL_RECORD_BITS) + pos;
  69     ptr.p = (pageP->m_data + pos);
  70     pageP->m_data[pos+m_record_info.m_offset_magic] = ~(Uint32)m_record_info.m_type_id;
  71     m_current_pos = pos + size;
  72     m_current_ref_count++;
  73     return true;
  74   }
  75
  76   return seize_new_page(ptr);
  77 }
  78
  79 inline
  80 void
  81 WOPool::release(Ptr<void> ptr)
  82 {
  83   Uint32 cur_page = m_current_page_no;
  84   Uint32 ptr_page = ptr.i >> POOL_RECORD_BITS;
  85   Uint32 *magic_ptr = (((Uint32*)ptr.p)+m_record_info.m_offset_magic);
  86   Uint32 magic_val = *magic_ptr;
  87
  88   if (likely(magic_val == ~(Uint32)m_record_info.m_type_id))
  89   {
  90     * magic_ptr = 0;
  91     if (cur_page == ptr_page)
  92     {
  93       if (m_current_ref_count == 1)
  94       {
  95         m_current_pos = 0;
  96       }
  97       m_current_ref_count--;
  98       return;
  99     }
 100     return release_not_current(ptr);
 101   }
 102   handle_invalid_release(ptr);
 103 }
 104
 105 inline
 106 void*
 107 WOPool::getPtr(Uint32 i)
 108 {
 109   Uint32 page_no = i >> POOL_RECORD_BITS;
 110   Uint32 page_idx = i & POOL_RECORD_MASK;
 111   WOPage * page = m_memroot + page_no;
 112   Uint32 * record = page->m_data + page_idx;
 113   Uint32 magic_val = * (record + m_record_info.m_offset_magic);
 114   if (likely(magic_val == ~(Uint32)m_record_info.m_type_id))
 115   {
 116     return record;
 117   }
 118   handle_invalid_get_ptr(i);
 119   return 0;                                     /* purify: deadcode */
 120 }
 121
 122 #endif