OW_RWLocker.hpp

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#ifndef OW_RWLOCKER_HPP_INCLUDE_GUARD_
#define OW_RWLOCKER_HPP_INCLUDE_GUARD_
#include "OW_config.h"
#include "OW_NonRecursiveMutexLock.hpp"
#include "OW_Condition.hpp"
#include "OW_Exception.hpp"
#include "OW_Array.hpp"

namespace OW_NAMESPACE
{

OW_DECLARE_APIEXCEPTION(RWLocker, OW_COMMON_API);
class OW_COMMON_API RWLocker
{
public:
   RWLocker();
   ~RWLocker();
   void getReadLock(UInt32 sTimeout, UInt32 usTimeout=0);
   void getWriteLock(UInt32 sTimeout, UInt32 usTimeout=0);
   void releaseReadLock();
   void releaseWriteLock();
private:
   void doWakeups();
   Condition   m_waiting_writers;
   Condition   m_waiting_readers;
   
   int         m_num_waiting_writers;
   int         m_num_waiting_readers;
   int         m_readers_next;
   
   NonRecursiveMutex m_guard;
   // -1 means writer has lock.  0 means no one has the lock. 
   // > 0 means readers have the lock.
   int m_state;

#ifdef OW_WIN32
#pragma warning (push)
#pragma warning (disable: 4251)
#endif

   Array<Thread_t> m_readers;

#ifdef OW_WIN32
#pragma warning (pop)
#endif

   Thread_t m_writer;
};
class OW_COMMON_API ReadLock
{
public:
   ReadLock(RWLocker& locker, UInt32 sTimeout, UInt32 usTimeout=0)
      : m_locker(&locker)
      , m_released(false)
   {
      m_locker->getReadLock(sTimeout, usTimeout);
   }
   ~ReadLock()
   {
      release();
   }
   void lock(UInt32 sTimeout, UInt32 usTimeout=0)
   {
      if (m_released)
      {
         m_locker->getReadLock(sTimeout, usTimeout);
         m_released = false;
      }
   }
   void release()
   {
      if (!m_released)
      {
         m_locker->releaseReadLock();
         m_released = true;
      }
   }
private:
   RWLocker* m_locker;
   bool m_released;
   // noncopyable
   ReadLock(const ReadLock&);
   ReadLock& operator=(const ReadLock&);
};
class OW_COMMON_API WriteLock
{
public:
   WriteLock(RWLocker& locker, UInt32 sTimeout, UInt32 usTimeout=0)
      : m_locker(&locker)
      , m_released(false)
   {
      m_locker->getWriteLock(sTimeout, usTimeout);
   }
   ~WriteLock()
   {
      release();
   }
   void lock(UInt32 sTimeout, UInt32 usTimeout=0)
   {
      if (m_released)
      {
         m_locker->getWriteLock(sTimeout, usTimeout);
         m_released = false;
      }
   }
   void release()
   {
      if (!m_released)
      {
         m_locker->releaseWriteLock();
         m_released = true;
      }
   }
private:
   RWLocker* m_locker;
   bool m_released;
   
   // noncopyable
   WriteLock(const WriteLock&);
   WriteLock& operator=(const WriteLock&);
};

} // end namespace OW_NAMESPACE

#endif

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