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Subj : Re: Boss Told Me You Can't Use Semaphore, But I Have To Do
To   : comp.programming.threads
From : Dragan Cvetkovic
Date : Wed Jul 13 2005 05:34 pm

Chris Friesen <cfriesen@nortel.com> writes:

> David Schwartz wrote:
>
>>     Semaphores were originally designed to be process-shared and do this
>> in a natural way. Mutexes were originally designed to be process-local,
>> and have process-shared support hacked on. For example, to create a
>> semaphore, you just call the semaphore create function. To create a
>> process-shared mutex, you have to allocate shared memory and then put the
>> mutex in it.
>
> With semas, you have something like:
>
> semget() -- creation
> semctl() -- initialization
> semop() -- lock
> semop() -- unlock


Don't forget POSIX semaphores:

sem_open(), sem_post(), sem_wait(), sem_close(), sem_unlink(). 

They should be able to work both between threads and between processes, but
not all OSes support them fully.

Dragan

-- 
Dragan Cvetkovic, 

To be or not to be is true. G. Boole      No it isn't.  L. E. J. Brouwer

!!! Sender/From address is bogus. Use reply-to one !!!

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