On 1/9/13 7:21 AM, Richard Sharpe wrote:
On Tue, 2013-01-08 at 09:20 -0800, Adrian Chadd wrote:
On 8 January 2013 08:15, Richard Sharpe <rsha...@richardsharpe.com> wrote:
On Tue, 2013-01-08 at 07:36 -0800, Adrian Chadd wrote:
.. or you could abstract it out a bit and use freebsd's
aio_waitcomplete() or kqueue aio notification.
It'll then behave much saner.
Yes, going forward that is what I want to do ... this would work nicely
with a kqueue back-end for Samba's tevent subsystem, and if someone has
not already written such a back end, I will have to do so, I guess.
Embrace FreeBSD's nice asynchronous APIs for doing things! You know you want to!
(Then, convert parts of samba over to use grand central dispatch... :-)
Seriously though - I was doing network/disk IO using real time signals
what, 10 + years ago on Linux and it plain sucked. AIO + kqueue +
waitcomplete is just brilliant. kqueue for signal delivery is also
just brilliant. Just saying.
The problem with a fully event-driven approach is that it will not work,
it seems to me. Eventually, you find something that is not async and
then you have to go threaded. (Because handling multiple clients in one
process is very useful and you do not want client-A's long-running op
preventing client-B's short-running op from being serviced.)
Then, you run into problems like Posix's insistence that all threads in
a process must use the same credentials (ie, uid and gids must be the
same across all threads), although there is a hack on Linux to work
around this behind glibc's back.
The best implementation of an async framework I've seen is the one
that Alan Cox
and friends wrote in the code they sold to IronPort/Cisco.
It'd be nice if we could get that extracted out and donated/included
into something
generally available.. even had a #ifdef Linux code path..
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