[cl-stm-devel] Counter example

[Hoan Ton-That]

Hey folks,

Transactions can be parametrized by other transactions.
For testing purposes we may want a transaction to pause
for two seconds after its calculation.  We can define a
higher order transaction that does this:

(deftransaction sleep-after (seconds transaction)
  transaction
  (trans (sleep seconds)))

With the counter example loaded (the source can be found
in src/examples/counter.lisp) we can now see what happens
when two transactions conflict.

STM> (defvar *counter* (new 'counter))
*COUNTER*
STM> (progn (perform (sleep-after 2 (increment *counter*)))
            (perform (sleep-after 2 (increment *counter*))))
[debugging output elided...]
STM> (value-of (count-of *counter*))
2
STM>

If you looked at the debugging output you would see one
of the transactions has retried due to an inconsistent log.

I'm sorry that I haven't been posting regularly, but I've been
making steady progress.  I'm managing to work on it, however
small everyday.  I'll be posting more regularly this week with
snippets like these.

Hoan