/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
(or a modified version of those libraries),
containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
licensors of this Program grant you additional
permission to convey the resulting work. Corresponding Source for a
non-source form of such a combination shall include the source code for
the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
work.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnUtils/Private/Win32/pnUtW32Sync.cpp
*   
***/

#include "../pnUtils.h"


/****************************************************************************
*
*   Spin lock functions
*
***/

//===========================================================================
static inline void EnterSpinLock (long * spinLock) {
    for (;;)
        if (*spinLock < 0)
            if (!InterlockedIncrement(spinLock))
                return;
            else
                InterlockedDecrement(spinLock);
}

//===========================================================================
static inline void LeaveSpinLock (long * spinLock) {
    InterlockedDecrement(spinLock);
}


/****************************************************************************
*
*   CLockWaitSet / CLockWaitSetAllocator
*
***/

class CLockWaitSet {
private:
    unsigned m_refCount;
    HANDLE   m_waitEvent;

public:
    LINK(CLockWaitSet) link;

    inline CLockWaitSet ();
    inline ~CLockWaitSet ();
    inline void DecRef ();
    inline void IncRef ();
    inline void Signal ();
    inline void Wait ();
};

class CLockWaitSetAllocator {
private:
    CLockWaitSet                   m_array[256];
    CLockWaitSetAllocator *        m_prev;
    LISTDECL(CLockWaitSet, link)   m_spareList;
    LISTDECL(CLockWaitSet, link)   m_usedList;

    static CLockWaitSetAllocator * s_allocator;
    static long                    s_spinLock;

public:
    CLockWaitSetAllocator (CLockWaitSetAllocator * prev);
    ~CLockWaitSetAllocator ();
    static CLockWaitSet * Alloc ();
    static void Free (CLockWaitSet * waitSet);
    static void __cdecl Shutdown ();
};

CLockWaitSetAllocator * CLockWaitSetAllocator::s_allocator;
long                    CLockWaitSetAllocator::s_spinLock = -1;

//===========================================================================
CLockWaitSet::CLockWaitSet () {
    m_refCount  = 0;
    m_waitEvent = CreateEvent(nil, true, false, nil);
}

//===========================================================================
CLockWaitSet::~CLockWaitSet () {
    ASSERT(!m_refCount);
    CloseHandle(m_waitEvent);
    m_waitEvent = 0;
}

//===========================================================================
void CLockWaitSet::DecRef () {
    ASSERT(m_refCount);
    if (!--m_refCount) {
        ResetEvent(m_waitEvent);
        CLockWaitSetAllocator::Free(this);
    }
}

//===========================================================================
void CLockWaitSet::IncRef () {
    ++m_refCount;
}

//===========================================================================
void CLockWaitSet::Signal () {
    ASSERT(m_refCount);
    SetEvent(m_waitEvent);
}

//===========================================================================
void CLockWaitSet::Wait () {
    ASSERT(m_refCount);
    WaitForSingleObject(m_waitEvent, INFINITE);
}

//===========================================================================
CLockWaitSetAllocator::CLockWaitSetAllocator (CLockWaitSetAllocator * prev) {
    m_prev = prev;
    if (prev) {
        m_spareList.Link(&prev->m_spareList);
        m_usedList.Link(&prev->m_usedList);
    }
    for (unsigned index = arrsize(m_array); index--; )
        m_spareList.Link(&m_array[index]);
}

//===========================================================================
CLockWaitSetAllocator::~CLockWaitSetAllocator () {
    delete m_prev;
}

//===========================================================================
CLockWaitSet * CLockWaitSetAllocator::Alloc () {
    EnterSpinLock(&s_spinLock);

    // If there is no active allocator or if the active allocator is full,
    // create a new one
    if (!s_allocator || !s_allocator->m_spareList.Head()) {
        if (!s_allocator)
            atexit(Shutdown);
        s_allocator = new CLockWaitSetAllocator(s_allocator);
    }

    // Get an available wait set from the active allocator
    CLockWaitSet * waitSet = s_allocator->m_spareList.Head();
    s_allocator->m_usedList.Link(waitSet);

    LeaveSpinLock(&s_spinLock);
    return waitSet;
}

//===========================================================================
void CLockWaitSetAllocator::Free (CLockWaitSet * waitSet) {
    EnterSpinLock(&s_spinLock);

    // Return this wait set to the active allocator's spare list
    ASSERT(s_allocator);
    s_allocator->m_spareList.Link(waitSet);

    LeaveSpinLock(&s_spinLock);
}

//===========================================================================
void CLockWaitSetAllocator::Shutdown () {
    EnterSpinLock(&s_spinLock);

    // Free all allocators
    while (s_allocator) {
        CLockWaitSetAllocator * prev = s_allocator->m_prev;
        delete s_allocator;
        s_allocator = prev;
    }

    LeaveSpinLock(&s_spinLock);
}


/****************************************************************************
*
*   CLock
*
***/

//===========================================================================
CLock::CLock () {
    m_waitSet     = nil;
    m_spinLock    = -1;
    m_readerCount = 0;
    m_writerCount = 0;
}

//===========================================================================
CLock::~CLock () {
    ASSERT(!m_waitSet);
    ASSERT(m_spinLock == -1);
    ASSERT(!m_readerCount);
    ASSERT(!m_writerCount);
}

//===========================================================================
void CLock::EnterRead () {
    EnterSpinLock(&m_spinLock);
    for (;;) {

        // If there are no writers, claim this lock for reading
        if (!m_writerCount) {
            ++m_readerCount;
            break;
        }

        // Otherwise, wait until the existing writer releases the lock
        CLockWaitSet * waitSet = m_waitSet = (m_waitSet ? m_waitSet : CLockWaitSetAllocator::Alloc());
        waitSet->IncRef();
        LeaveSpinLock(&m_spinLock);
        waitSet->Wait();
        EnterSpinLock(&m_spinLock);
        waitSet->DecRef();

    }
    LeaveSpinLock(&m_spinLock);
}

//===========================================================================
void CLock::EnterWrite () {
    EnterSpinLock(&m_spinLock);
    for (;;) {

        // If there are no readers or writers, claim this lock for writing
        if (!m_readerCount && !m_writerCount) {
            ++m_writerCount;
            break;
        }

        // Otherwise, wait until the existing writer or all existing readers
        // release the lock
        CLockWaitSet * waitSet = m_waitSet = (m_waitSet ? m_waitSet : CLockWaitSetAllocator::Alloc());
        waitSet->IncRef();
        LeaveSpinLock(&m_spinLock);
        waitSet->Wait();
        EnterSpinLock(&m_spinLock);
        waitSet->DecRef();

    }
    LeaveSpinLock(&m_spinLock);
}

//===========================================================================
void CLock::LeaveRead () {
    EnterSpinLock(&m_spinLock);

    // If this is the last reader, signal waiting threads to try claiming
    // the lock again
    ASSERT(m_readerCount);
    if (!--m_readerCount)
        if (m_waitSet) {
            m_waitSet->Signal();
            m_waitSet = nil;
        }

    LeaveSpinLock(&m_spinLock);
}

//===========================================================================
void CLock::LeaveWrite () {
    EnterSpinLock(&m_spinLock);

    // This is the last writer. Signal waiting threads to try claiming the
    // lock again.
    ASSERT(m_writerCount == 1);
    --m_writerCount;
    if (m_waitSet) {
        m_waitSet->Signal();
        m_waitSet = nil;
    }

    LeaveSpinLock(&m_spinLock);
}


/*****************************************************************************
*
*   CEvent
*
***/

//============================================================================
CEvent::CEvent (
    ECEventResetBehavior resetType,
    bool                 initialSet
) {
    m_handle = CreateEvent(
        nil,    // security attributes
        (resetType == kEventManualReset) ? true : false,
        initialSet,
        nil     // name
    );
}

//============================================================================
CEvent::~CEvent () {
    (void) CloseHandle(m_handle);
}

//============================================================================
void CEvent::Signal () {
    SetEvent(m_handle);
}

//============================================================================
void CEvent::Reset () {
    ResetEvent(m_handle);
}

//============================================================================
bool CEvent::Wait (unsigned waitMs) {
    ThreadAssertCanBlock(__FILE__, __LINE__);
    return WaitForSingleObject(m_handle, waitMs) == WAIT_OBJECT_0;
}


/****************************************************************************
*
* Exported functions
*
***/

//===========================================================================
long AtomicAdd (long * value, long increment) {
    return InterlockedExchangeAdd(value, increment);
}

//===========================================================================
long AtomicSet (long * value, long set) {
    return InterlockedExchange(value, set);
}
