Re: [Corelinux-develop] Smart Pointers

[Frank V. C. <fr...@co...>]

Ian Crawford wrote:

>On Sun, 9 Sep 2001, Frank V. Castellucci wrote:
>
>>To answer your first question:
>>
>>It is all to often we see the myopic view of the world where context
>>often become part of a static type. For example, rather than take the
>>time to create things like semaphore pools, a developer unilateraly
>>decided that each SP type (A, B, Foo, etc.) has a single semaphore in a
>>static variable. ugh.
>>
>
>Um... I don't follow.  I'm sure it's just my inexperience shining
>through.
>
>Each SP obviously needs a (dumb) pointer and a reference count.
>Modifications to these need to be thread safe, right?  Now... it would be
>pure evil to give each SP type a static locking mechanism.  I've done it
>by giving each SP instance a mutex, but is this overkill?
>
It is overkill, but I believe you get the idea of the semaphore (mutex) 
pool now.

>
>You mention semaphores... are you talking about implementing
>mutexes/critical sections (for pointer/ref. count mods) with semaphores?
>If not, I'm lost.
>
You are not lost, and I apologize if my phrasing isn't clear, your doing 
fine.

>
>As for semaphore pools... are you talking about something clever to avoid
>my (wasteful?) "mutex for each instance" scheme?  Like I said, I don't
>follow.  :(
>
You follow, this is a clever way, but has a price.

>
>
>>And now that you brought it up (if you knew it or not with reference count):
>>
>>8. Reference counts must be guarded
>>9. Object state must be guarded
>>
>>Thoughts?
>>
>
>Does this replace #7 or is it over and above it?  If the latter, then what
>does #7 really mean?
>
Again, re-entrancy and guarded (mutex) are two different things neh?

>
>
>[for reference...]
>
>>>>7. Must be re-entrent
>>>>
>