//%2006////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
// Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
// Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation, The Open Group.
// Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; Symantec Corporation; The Open Group.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// furnished to do so, subject to the following conditions:
// 
// THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
// ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
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// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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//==============================================================================
//
//%/////////////////////////////////////////////////////////////////////////////

#ifndef Pegasus_ReadWriteSem_h
#define Pegasus_ReadWriteSem_h

#include <Pegasus/Common/Config.h>
#include <Pegasus/Common/Linkage.h>
#include <Pegasus/Common/Semaphore.h>
#include <Pegasus/Common/Mutex.h>
#include <Pegasus/Common/AtomicInt.h>

PEGASUS_NAMESPACE_BEGIN

/**
    Every platform should decide which implementation for read/write locks
    should be used in OpenPegasus by defining one of the following:
    1.) PEGASUS_USE_POSIX_RWLOCK - POSIX standard based implementation
    2.) PEGASUS_USE_SEMAPHORE_RWLOCK - mutex based implementation
 
    The definition for each platform can be found in the according platform
    header file: pegasus/src/Pegasus/Common/Platform_<Platform>.h
*/

#if !defined(PEGASUS_USE_POSIX_RWLOCK) && !defined(PEGASUS_USE_SEMAPHORE_RWLOCK)
# error "Unsupported platform: ReadWriteSem.h implementation type missing"

#endif

//==============================================================================
//
// ReadWriteSemRep
//
//==============================================================================

#ifdef PEGASUS_USE_POSIX_RWLOCK
struct ReadWriteSemRep
{
    pthread_rwlock_t rwlock;
};
#endif /* PEGASUS_USE_POSIX_RWLOCK */

#ifdef PEGASUS_USE_SEMAPHORE_RWLOCK
struct ReadWriteSemRep
{
    Semaphore _rlock;
    Mutex _wlock;
    Mutex _internal_lock;
    AtomicInt _readers;
    AtomicInt _writers;
    ReadWriteSemRep() :
        _rlock(10), _wlock(), _internal_lock(), _readers(0), _writers(0)
    {
    }
};
#endif /* PEGASUS_USE_POSIX_RWLOCK */

//==============================================================================
//
// ReadWriteSem
//
//==============================================================================

class PEGASUS_COMMON_LINKAGE ReadWriteSem
{
public:

    ReadWriteSem();

    ~ReadWriteSem();

    void waitRead();

    void waitWrite();

    void unlockRead();

    void unlockWrite();

private:

    ReadWriteSemRep _rwlock;
};

//==============================================================================
//
// ReadLock
//
//==============================================================================

class ReadLock
{
public:

    ReadLock(ReadWriteSem& rwsem) : _rwsem(rwsem)
    {
        _rwsem.waitRead();
    }

    ~ReadLock()
    {
        _rwsem.unlockRead();
    }

private:
    ReadWriteSem & _rwsem;
};

//==============================================================================
//
// WriteLock
//
//==============================================================================

class WriteLock
{
public:

    WriteLock(ReadWriteSem& rwsem) : _rwsem(rwsem)
    {
        _rwsem.waitWrite();
    }

    ~WriteLock()
    {
        _rwsem.unlockWrite();
    }

private:
    ReadWriteSem & _rwsem;
};

PEGASUS_NAMESPACE_END

#endif /* Pegasus_ReadWriteSem_h */