NLMISC::CFastMutex Class Reference

#include <mutex.h>

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Detailed Description

Fast mutex implementation (not fairly) The mutex ARE NOT recursive (ie don't call enter() several times on the same mutex from the same thread without having called leave()) ; The threads ARE NOT woken-up in the same order as they were put to sleep. The threads ARE NOT woken-up using signals but using Sleep(). This mutex works but is not optimal for multiprocessors because if the mutex is locked, next enter will be sleeped without waiting a little.

Implementation notes:

• Implementated under WIN32
• Other OS use CMutex

Tested: OK on Windows and Linux single & multi-processor

 CFastMutex m;
 m.enter ();
 // do critical stuffs
 m.leave ();
 *

Author:

Cyril 'Hulud' Corvazier

Olivier Cado

Nevrax France

Date:

2002, 2003

Definition at line 194 of file mutex.h.

Public Member Functions
	CFastMutex ()
	Constructor.
__forceinline void	enter () volatile
void	init () volatile
	Same as constructor, useful for init in a shared memory block.
__forceinline void	leave () volatile
Static Public Member Functions
__forceinline bool	atomic_swap (volatile uint32 *lockPtr)
	Atomic swap.
Private Attributes
volatile uint32	_Lock

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Constructor & Destructor Documentation

NLMISC::CFastMutex::CFastMutex (   )  [inline]

Constructor. Definition at line 199 of file mutex.h. References _Lock. : _Lock(0) {}

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Member Function Documentation

__forceinline bool NLMISC::CFastMutex::atomic_swap (  volatile uint32 *  lockPtr  )  [inline, static]

Atomic swap. Definition at line 205 of file mutex.h. References ASM_ASWAP_FOR_GCC_XCHG, and uint32. Referenced by enter(). { uint32 result; #ifdef NL_OS_WINDOWS #ifdef NL_DEBUG_FAST // Workaround for dumb inlining bug (returning of function goes into the choux): push/pop registers __asm { push eax push ecx mov ecx,lockPtr mov eax,1 xchg [ecx],eax mov [result],eax pop ecx pop eax } #else __asm { mov ecx,lockPtr mov eax,1 xchg [ecx],eax mov [result],eax } #endif #else ASM_ASWAP_FOR_GCC_XCHG #endif // NL_OS_WINDOWS return result != 0; }

__forceinline void NLMISC::CFastMutex::enter (   )  volatile [inline]

Definition at line 238 of file mutex.h. References _Lock, atomic_swap(), and uint. Referenced by NLMISC::CBlockMemory< CNode >::__stl_alloc_changeEltSize(), NLMISC::CBlockMemory< CNode >::allocate(), NLMISC::CBlockMemory< CNode >::free(), NLMISC::CBlockMemory< CNode >::purge(), and RenderTriangle(). { //std::cout << "Entering, Lock=" << _Lock << std::endl; if (atomic_swap (&_Lock)) { // First test uint i; for (i = 0 ;; ++i) { uint wait_time = i + 6; // Increment wait time with a log function if (wait_time > 27) wait_time = 27; // Sleep if (wait_time <= 20) wait_time = 0; else wait_time = 1 << (wait_time - 20); if (!atomic_swap (&_Lock)) break; #ifdef NL_OS_WINDOWS Sleep (wait_time); #else //std::cout << "Sleeping i=" << i << std::endl; usleep( wait_time*1000 ); #endif } } }

void NLMISC::CFastMutex::init (  void   )  volatile [inline]

Same as constructor, useful for init in a shared memory block. Definition at line 202 of file mutex.h. References _Lock. { _Lock = 0; }

__forceinline void NLMISC::CFastMutex::leave (   )  volatile [inline]

Definition at line 273 of file mutex.h. References _Lock. Referenced by NLMISC::CBlockMemory< CNode >::__stl_alloc_changeEltSize(), NLMISC::CBlockMemory< CNode >::allocate(), NLMISC::CBlockMemory< CNode >::free(), NLMISC::CBlockMemory< CNode >::purge(), and RenderTriangle(). { _Lock = 0; //std::cout << "Leave" << std::endl; }

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Field Documentation

volatile uint32 NLMISC::CFastMutex::_Lock [private]

Definition at line 280 of file mutex.h. Referenced by CFastMutex(), enter(), init(), and leave().

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The documentation for this class was generated from the following file:

• mutex.h

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