Wefts is out - comp.programming.threads

Message from discussion Wefts is out

SenderX

More options Aug 23 2003, 11:45 am

Newsgroups: comp.programming.threads

From: "SenderX" <x...@xxx.xxx>

Date: Sat, 23 Aug 2003 15:45:21 GMT

Local: Sat, Aug 23 2003 11:45 am

Subject: Re: Wefts is out

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> Because I wanted to implement some lock free algo as separate classes,
like
> the lock free list.

This is one of the best lock-free lists out there:

You can implement this algo. in x86.

I already have, and will probably post the code.

I have a special lock-free read-write mutex, that will allow for objects
that depend on membership in a collection, to exists in the lock-free list.

> You know that lock free algos are not always the best,
> or even not always desiderable (i.e. if you want to wait for a socket to
> become readable

Yep. That's what IOCP is for. On Win32 that is...

;)

> So, I would give it a try and put them on wefts...

Yes, you could put them in a separate namespace:

Wefts::LockFree::x86::

Here is another cool lock-free linked-list, using the wonderful atomic_ptr:

Here is atomic_ptr:

This is a cas64 function:

/* Atomic 64-bit Cas */
inline bool

cas64
(
void volatile* pDest,
void* pComprand,
void* pExchange
)

{
// Validate alignment
assert( ! ( (int)pDest % sizeof( __int64 ) ) );

unsigned char ucRet;

__asm
{
/* Read comprand */
mov esi, [pComprand]
mov eax, [esi + 0]
mov edx, [esi + 4]

/* Read exchange */
mov esi, [pExchange]
mov ebx, [esi + 0]
mov ecx, [esi + 4]

/* Read dest */
mov esi, [pDest]

/* Execute */

#ifdef AC_BUILD_PROC_SMP

lock cmpxchg8b qword ptr [esi]

#else

cmpxchg8b qword ptr [esi]

#endif

/* Test */
sete ucRet
jz cas64_Success

/* Update comprand */
mov esi, [pComprand]
mov [esi + 0], eax;
mov [esi + 4], edx;
};

cas64_Success:

return ( ucRet ) ? true : false;

}

Pointer passed as dest, will have to be QWORD aligned, on SMP box's.

--
The designer of the experimental, SMP and HyperThread friendly, AppCore
library.

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