Re: protected type interrupts

[Jean-Pierre Rosen <rosen@adalog.fr>]

REH a �crit :

> I don't understand.  How can a procedure within a protected object
> modify data internal to the object in a thread-safe way without the
> potentially blocking effect of enforcing mutual exclusion?  If one task
> is "using" the object, and another calls one of the object's
> procedures, would the second task not be blocked until the first one
> exits the object?  
> 
The goal of the "potentially blocking" rule is to prevent *unbounded* 
blocking. Short blockings, such as those require to provide mutual 
exclusion, are OK, because thay are bounded.

Think of it this way: if it can be implemented on a multi-processor by a 
simple spin-lock, it is not potentially blocking. If it requires a 
queue, and being awaken depends on some non determinable condition, it 
is potentially blocking.
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            J-P. Rosen (rosen@adalog.fr)
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