>I think it would be quite useful so long as it's implemented correctly.

Reminds me of the time where this guy wanted to start a development project and stated the goals to us, including such oddities as "bug free software" and "fast code"... ;)

Well, the Posix implementation shouldn't be a problem, really. The Windows stuff is - not intuitive. The worst about the SignalAndWait() function in Windows is that I can't use a CriticalSection there. Now is the time to ask if it's worth replacing CriticalSection for Mutex in the synchronized() blocks... Either way the implementation on Windows will be less elegant.

>  And the design seems pretty clean and straightforward.  I'll certainly
>want condvars once I start doing application coding in D.
>

Yeah, I think we will need them to be able to lure Java and C# people to D. (However, the syntax in C# wasn't very attractive, so I wonder if anyone uses it.)

Tommie Gannert wrote:
>> I think it would be quite useful so long as it's implemented correctly. 
> 
> Reminds me of the time where this guy wanted to start a development project and
> stated the goals to us, including such oddities as "bug free software" and "fast
> code"... ;)
> 
> Well, the Posix implementation shouldn't be a problem, really. The Windows stuff
> is - not intuitive. The worst about the SignalAndWait() function in Windows is
> that I can't use a CriticalSection there. Now is the time to ask if it's worth
> replacing CriticalSection for Mutex in the synchronized() blocks... Either way
> the implementation on Windows will be less elegant.

hehe, I said that only because getting it right on Windows is so difficult :)  The Boost implementation uses something like three semaphores and I've heard comments that it still has issues (though this was a while ago).

>>  And the design seems pretty clean and straightforward.  I'll certainly want condvars once I start doing application coding in D.
> 
> Yeah, I think we will need them to be able to lure Java and C# people to D.
> (However, the syntax in C# wasn't very attractive, so I wonder if anyone uses
> it.)

Windows people tend not to be particularly familiar with condvars, but they're about the only way I know of to do multiple producer/consumer correctly.  All the standard Windows methods I know of tend to have subtle races and spurious wakeup problems.  This is one area that Java has become quite nice, thanks, I suppose, to Doug Lea.


Sean

Sean Kelly wrote:
> Tommie Gannert wrote:
>>> I think it would be quite useful so long as it's implemented correctly. 
>>
>> Reminds me of the time where this guy wanted to start a development project and
>> stated the goals to us, including such oddities as "bug free software" and "fast
>> code"... ;)
>>
>> Well, the Posix implementation shouldn't be a problem, really. The Windows stuff
>> is - not intuitive. The worst about the SignalAndWait() function in Windows is
>> that I can't use a CriticalSection there. Now is the time to ask if it's worth
>> replacing CriticalSection for Mutex in the synchronized() blocks... Either way
>> the implementation on Windows will be less elegant.
> 
> hehe, I said that only because getting it right on Windows is so difficult :)  The Boost implementation uses something like three semaphores and I've heard comments that it still has issues (though this was a while ago).

This topic resurfaced again recently on c.p.t so I did a bit of looking.  There are three pseudocode implementations for condvars in this (somewhat old) thread:

http://groups.google.com/group/comp.programming.threads/browse_frm/thread/6191877e72ccb3fe/846010a82d6c51b0#846010a82d6c51b0

Also, this project likely has a correct pthread implementation for Win32, though it uses the LGPL license:

http://sourceware.org/pthreads-win32/

It's worth noting that this project uses an algorithm described in the aforementioned usenet thread (Algorithm 8a).  If I suddenly find some time to play with this I'll translate one of the algothms (8a or 8c) to D code--it would be great to have cross-platform condvar support in D.


Sean