lock oneself?

Hi,

I want to emulate aqcuire/release on locks. Traditionally, acquire called  
on acquired lock in the same process sleeps until the lock is released;  
other lisp (and non-lisp) environments do just that.

In Lispworks, I can't find a way to sleep on my own lock.  I need it for  
the following scenario:

The reader fetches the last item from the queue. After that, it raises a  
semaphore, and waits on the semaphore until the writer opens it.

How can I code it with Lispworks locks?

David

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