Patch: General locking (was Possible deadlock and solution)

[Matthias Andree]

On Tue, 01 Oct 2002, David Relson wrote:

> >You'd usually clean up in the reverse order of allocation, last
> >allocated, first freed. It's also simpler code-wise ;-)
> 
> Counting down to zero has a nice simplicity as well.  Of course, if 
> counting down is so superior, then the locking should also be done via 
> count down <My turn to duck and run ...>

So do it :-)

> (On a side note, have you ever worked with a machine architecture in which 
> the index registers are _subtracted_ from the array address?  It makes for 
> interesting assembly language coding.)

6502 and m68k don't do this. However, I found raw assembly too
cumbersome, so I went for the globally-optimizing macro assembler: C.
;-)

> >singly-linked lists stink <ducks & runs for cover>
> 
> Sometimes that's all that's needed.  For sure, they're easier to deal with 
> than doubly-linked lists.  For the case in hand, with a linked list, one 
> knows that allocation is done when the end of the list is reached.  No need 
> to count !

Yes, that's fine, provided your rollback works (I often catch off-by-one
errors when using lists...). No big deal.  If it saves setup cost (like
converting the list to an array), then go for linked lists.

In the duck & run section, we could go for C++ STL "vector"s to save
us the manual setup...

-- 
Matthias Andree