genesis-3d_engine/Engine/foundation/threading/win360/win360criticalsection.h

#pragma once
/****************************************************************************
Copyright (c) 2006, Radon Labs GmbH
Copyright (c) 2011-2013,WebJet Business Division,CYOU
 
http://www.genesis-3d.com.cn

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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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 "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/

#include "core/types.h"     
#include "core/sysfunc.h"

#if __XBOX360__
// on xbox360 the critical section implementation seems to do the same as the windows user implementation
#define NEBULA3_USER_CRITICAL_SECTION 0
#else
// user implementation bases on "Fast critical sections with timeout" by Vladislav Gelfer
#define NEBULA3_USER_CRITICAL_SECTION 1
#endif

#if NEBULA3_USER_CRITICAL_SECTION
extern "C" void _WriteBarrier();
extern "C" void _ReadWriteBarrier();
#pragma intrinsic(_WriteBarrier)
#pragma intrinsic(_ReadWriteBarrier)
#endif
//------------------------------------------------------------------------------
namespace Win360
{
class Win360CriticalSection
{
public:
    /// constructor
    Win360CriticalSection();
    /// destructor
    ~Win360CriticalSection();
    /// enter the critical section
    void Enter() const;
    /// leave the critical section
    void Leave() const;
private:

#if NEBULA3_USER_CRITICAL_SECTION
    /// lock with increment
    bool PerfLockImmediate(DWORD dwThreadID) const;
    /// lock with semaphore
    bool PerfLock(DWORD dwThreadID) const;
    /// performance lock with system wait and kernel mode 
    bool PerfLockKernel(DWORD dwThreadID) const;
    /// unlock
    void PerfUnlock() const; 
    /// increment waiter count
    void WaiterPlus() const; 
    /// decrement waiter count
    void WaiterMinus() const;
    /// allocate semaphore if not done yet
    void AllocateKernelSemaphore() const;

    // Declare all variables volatile, so that the compiler won't
    // try to optimize something important.
    mutable volatile DWORD	lockerThread;
    volatile DWORD	spinMax;   
    mutable volatile long	waiterCount; 
    mutable volatile HANDLE	semaphore;
    mutable uint recursiveLockCount;
#else                                        
    mutable CRITICAL_SECTION criticalSection;
#endif
};         

#if !NEBULA3_USER_CRITICAL_SECTION
//------------------------------------------------------------------------------
/**
*/      
inline
Win360CriticalSection::Win360CriticalSection()
{
    InitializeCriticalSectionAndSpinCount(&this->criticalSection, 4096);
}

//------------------------------------------------------------------------------
/**
*/
inline
Win360CriticalSection::~Win360CriticalSection()
{
    DeleteCriticalSection(&this->criticalSection);
}

//------------------------------------------------------------------------------
/**
*/
inline void
Win360CriticalSection::Enter() const
{
    EnterCriticalSection(&this->criticalSection);
}

//------------------------------------------------------------------------------
/**
*/
inline void
Win360CriticalSection::Leave() const
{
    LeaveCriticalSection(&this->criticalSection);
}

#else
//------------------------------------------------------------------------------
/**
*/
inline void Win360CriticalSection::WaiterPlus() const
{
    _InterlockedIncrement(&this->waiterCount);
}

//------------------------------------------------------------------------------
/**
*/
inline void Win360CriticalSection::WaiterMinus() const
{
    _InterlockedDecrement(&this->waiterCount);
}

//------------------------------------------------------------------------------
/**
*/
inline bool 
Win360CriticalSection::PerfLockImmediate(DWORD dwThreadID) const 
{
    return (0 == InterlockedCompareExchange((long*) &this->lockerThread, dwThreadID, 0));
}

//------------------------------------------------------------------------------
/**
*/
inline void
Win360CriticalSection::Enter() const
{
    DWORD threadId = GetCurrentThreadId();
    if (threadId != this->lockerThread)
    {
        if ((this->lockerThread == 0) &&
            this->PerfLockImmediate(threadId))
        {
            // single instruction atomic quick-lock was successful
        }            
        else
        {
            // potentially locked elsewhere, so do a more expensive lock with system critical section
            this->PerfLock(threadId);
        }
    }
    this->recursiveLockCount++;
}
//------------------------------------------------------------------------------
/**
*/
inline void 
Win360CriticalSection::AllocateKernelSemaphore() const
{
    if (!this->semaphore)
    {
        HANDLE handle = CreateSemaphore(NULL, 0, 0x7FFFFFFF, NULL);
        n_assert(NULL != handle);
        if (InterlockedCompareExchangePointer(&this->semaphore, handle, NULL))
            CloseHandle(handle); // we're late
    }
}

//------------------------------------------------------------------------------
/**
*/
inline bool
Win360CriticalSection::PerfLock(DWORD dwThreadID) const
{
    // Attempt spin-lock
    for (DWORD dwSpin = 0; dwSpin < spinMax; dwSpin++)
    {
        if (this->PerfLockImmediate(dwThreadID))
            return true;

        YieldProcessor();
    }
           
    // Ensure we have the kernel event created
    this->AllocateKernelSemaphore();

    // do a more expensive lock
    bool result = this->PerfLockKernel(dwThreadID);
    this->WaiterMinus();

    return result;
}

//------------------------------------------------------------------------------
/**
*/
inline bool 
Win360CriticalSection::PerfLockKernel(DWORD dwThreadID) const
{
    bool waiter = false;

    for (;;)
    {
        if (!waiter)
            this->WaiterPlus();

        if (PerfLockImmediate(dwThreadID))
            return true;

        n_assert(this->semaphore);
        switch (WaitForSingleObject(this->semaphore, INFINITE))
        {
        case WAIT_OBJECT_0:
            waiter = false;
            break;
        case WAIT_TIMEOUT:
            waiter = true;
            break;
        default:
            break;
        };
    }
    // unreachable
    //return false;
}

//------------------------------------------------------------------------------
/**
*/
inline void
Win360CriticalSection::Leave() const
{
    if (--recursiveLockCount == 0)
    {
        this->PerfUnlock();
    }        
}

//------------------------------------------------------------------------------
/**
*/
inline void
Win360CriticalSection::PerfUnlock() const
{
    _WriteBarrier(); // changes done to the shared resource are committed.

    this->lockerThread = 0;

    _ReadWriteBarrier(); // The CS is released.

    if (this->waiterCount > 0) // AFTER it is released we check if there're waiters.
    {
        WaiterMinus(); 
        ReleaseSemaphore(this->semaphore, 1, NULL);                  
    }
}
#endif
};
//------------------------------------------------------------------------------