| Transactions are obviously going to be expensive and complicated,
| which
| is why I suggested implementing them outside the core:
[...]
| That's not quite sufficient for full transactions either. We
| should also allow
| user code to replace the assignment op in the virtual machine too.
| (And
| whatever else Transactions.pm decides should be abortable.) Hmm. A
| transaction
| could be a simple copy-on-write with an exception handler that
| just restored
| all original values. That'd be efficient too because SVs can't
| move.
In the RFC, you can find a suggestion to a new pragma for the
transction-behaviour. Now the RFC is in the phase that it can
control various data sources, which can acts as a two-phase commit
clients! Not only database servers, but a simple file on a
filesystem also! (read v5 of the RFC. It is still on the way). Do
you know how effective it can be?
| Somebody ;) should go through the more challenging RFCs and try to
| distill
| out general features we could put in the internals to allow
| implementing
| the RFCs outside the core. That way we wouldn't hold up Perl 6
| while waiting
| for a research project to finish.
I don't know how it can be implemented outside the core. I think a
new keyword and a new pragma is required. Maybe the
transaction-handler can be a shared object, but I think this must be
in the core.
This can make perl more acceptable for the business: perl objects
are now can be transaction-safe! That can be rolled back, supports
two-phase commits, etc.
What it needs in the core is pretty small btw:
- a new keyword, which is similar to "local"
- some extension to the TIE interface (some new callbacks)
- some extension to the object interface (new callbacks)
- two-phase commit handler, rollback coordinator (the above two is
connected to this: very simple algorhythm!)
- lock/mutex handler
- (optional, because it is a very tough alg:) multi-version
concurrency control (MVCC) like in postgreSQL
If we forget about the MVCC, then all things are very
straightforward, aren't they? It is _not_ complicated at all. It is
all Perlish!
\---
dLux
--
< Szabó, Balázs Tibor - dLux > - HuLUG - Allinphos
( mailto:[EMAIL PROTECTED] http://www.dlux.hu ICQ: 30329785)
