include/Lock.h

   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 #ifndef LOCK_H
  17 #define LOCK_H
  18 #include<os.h>
  19 #include<Index.h>
  20 class Chunk;
  21 class Database;
  22 class Transaction;
  23
  24 class LockInfo
  25 {
  26     public:
  27     signed int noOfReaders_;
  28     //-1 indicates write lock is taken
  29
  30     unsigned char waitReaders_;
  31     unsigned char waitWriters_;
  32     LockInfo() { noOfReaders_ = 0; waitReaders_ = 0; waitWriters_ = 0; }
  33
  34 };
  35
  36 class LockHashNode
  37 {
  38     public:
  39     void *ptrToTuple_;
  40     LockInfo lInfo_;
  41     LockHashNode *next_;
  42     void print()
  43     {
  44         printf("<Lock Node>\n");
  45         printf("  <Tuple> %x </Tuple>\n", ptrToTuple_);
  46         printf("  <NoOfReaders> %d </NoOfReaders>\n", lInfo_.noOfReaders_);
  47         printf("  <WaitReaders> %x </WaitReaders>\n", lInfo_.waitReaders_);
  48         printf("  <WaitWriters> %x </WaitWriters>\n", lInfo_.waitWriters_);
  49         printf("</Lock Node>\n");
  50     }
  51 };
  52
  53 class LockListIter
  54 {
  55     LockHashNode *iter;
  56     public:
  57     LockListIter(){}
  58     LockListIter(LockHashNode *head) { iter = head;}
  59     LockHashNode* next();
  60     friend class LockList;
  61 };
  62
  63 class TransHasNode
  64 {
  65     public:
  66     LockHashNode *node_;
  67     TransHasNode *next_;
  68     void print() { node_->print(); }
  69 };
  70
  71 class DatabaseManagerImpl;
  72 //singleton
  73 //DatabaseManager has this object and give reference to it to
  74 //Table interface and so on.
  75 class LockManager
  76 {
  77     public:
  78     Database *systemDatabase_;
  79
  80     private:
  81     LockHashNode* allocLockNode(LockInfo &info, void *tuple);
  82     void deallocLockNode(LockHashNode *head, Bucket *bucket);
  83     Bucket* getLockBucket(void *tuple);
  84
  85     public:
  86
  87     LockManager(Database *sysDb_){ systemDatabase_ = sysDb_;}
  88     DbRetVal getSharedLock(void *tuple, Transaction **trans);
  89     DbRetVal getExclusiveLock(void * tuple, Transaction **trans);
  90     DbRetVal releaseLock(void *tuple);
  91     DbRetVal isExclusiveLocked(void *tuple, Transaction **trans, bool &status);
  92     void printUsageStatistics();
  93     void printDebugInfo();
  94 };
  95
  96
  97 #endif