Subj : Re: Linking without -lpthread doesn't fail??
To   : comp.programming.threads
From : David Schwartz
Date : Fri Oct 07 2005 06:59 am


"David Butenhof" <david.butenhof@hp.com> wrote in message 
news:7gu1f.14123$zm1.5268@news.cpqcorp.net...

> David Schwartz wrote:

>>     Frankly, I'm surprised it indicated the successful creation of a 
>> mutex and condition variable. I agree, it should not allow you to create 
>> a mutex and condition variable and then not time out.

> The non-thread pthread stubs SHOULD allow you to allocate and initialize 
> both mutexes and condition variables. You should be able to lock and 
> unlock mutexes -- there's no chance of lock contention because there's 
> only one thread. Some might implement lock and unlock as empty stubs; 
> others might do consistency checking.

    If it indicates the successful creation of a mutex and condition 
variable, then it should support their semantics. Otherwise, it's lying when 
it said it succeeded.

> You shouldn't be able to WAIT on a condition variable, because there's no 
> way the waiting thread could ever be awakened. But correct program logic 
> makes that irrelevant because there's no way a predicate could fail to be 
> satisfied (i.e., no reason to ever wait). Or at least, if there ever is a 
> reason/need to wait the program is completely broken anyway and will just 
> hang.

    Right except ...

> Timed wait is a special case, though, because there is a common idiom of 
> treating ETIMEDOUT as the predicate condition, and that can be satisfied 
> without another thread. In MY non-threaded stubs, the function 
> pthread_cond_timedwait() would simply "sleep" until the timeout.

    Exactly.

    DS

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