BTW: The repository is now public at:
http://bitbucket.org/eris0xaa/dendrite/ On Mon, Apr 12, 2010 at 10:02 AM, Jim Burnes <jvbur...@gmail.com> wrote: > Hi, Michael. > > I gathered that you've been away. Hope everything is going well at > BBC Research. > > I've been going over several architectural models for Dendrite lately. > It seems that, just as soon as I nail down one architecture and get > it implemented / tested, several new ideas occur to me. > > My latest realization with the 0.9 release is that, in trying to glue > Dendrite the OS level I almost created another Turing-complete > implementation of Dendrite. I think that sort of infinite recursion > is what's know as the Turing Tarpit. Generalizing your application > solution and then trying to generalize that. > > :-) > > In either case, since my OS connection layer needed a complete mailbox > system itself I figured that I would force myself to eat my own dog > food and implement the OS glue using Dendrite itself with a new async > component method I devised. This would allow me to create Console, > Session and CLI components that run within Dendrite. > > The trick with the async components so far is that I have to introduce > a "wait" primitive that handles the differences between POSIX and > Windows IO Requests. Now that I have that solved, one of the clever > library developers just *had* to ask me if my library would work > multi-core. > > Of course that question clarified some of the questions I'd been > asking myself. What would the correct Dendrite architecture look like > if it ran multi-threaded, multi-core. It turns out that the answer to > that solved other issues I've been having. > > Since Dendrite is a message passing system, making the handlers into > async components cleans up the multi-core issues. > > Also (and I think this part is pretty fascinating) one of the problems > with multi-threaded code is that to communicate between threads > requires a thread-safe mailbox. > > It turns out that there are such things. The simplest of course is to > use mutex locks around the critical mailbox send/receive code. But > mutexes are inefficient because they cause re-scheduling of the > blocked process. > > So you use a lock-free mechanism, but those are rare and somewhat > complex beasts. However there is a relatively simply mechanism that > allows a single-thread writer and single-thread reader (or > sender/receiver etc). It's a lock-free ring buffer. Normally the > one-writer, one-reader mechanism would be a limitation, but since each > Dendrite thread executes many cooperating components based on > co-routines it works out wonderfully. > > I even found a high-speed ring buffer that is cache coherent, so that > sibling threads (threads running on cores on the same CPU) are able to > communicate, thread-safe, at very high speeds. > > Anyway, you can see I'm kind of excited about all of this. The beauty > of this is, with a few changes to the way the async components work > and a new mailbox that is thread safe (at least to other threads), I > can make this thing scale way, way up. > > Then I'm really, really going to get back to the app I was writing > that I needed to write a messaging system for. :-) > > Jim > > > On Mon, Apr 12, 2010 at 9:37 AM, Michael Sparks <spark...@gmail.com> wrote: >> Hi Jim, >> >> >> On Mon, Mar 29, 2010 at 9:27 PM, Jim Burnes <jvbur...@gmail.com> wrote: >>> Kamaelia People, >>> >>> I've already sent this to Michael, but I thought I'd forward it to the group >>> because we're all in different time zones... >> >> I've been away from connectivity for the past couple of weeks, but now >> that I'm back I'd just like to say congratulations! :-) I'll try and >> take a look at my earliest opportunity. I've not used D, but this will >> be a nice introduction :-) >> >> Best Regards, >> >> Michael >> >> -- >> You received this message because you are subscribed to the Google Groups >> "kamaelia" group. >> To post to this group, send email to kamae...@googlegroups.com. >> To unsubscribe from this group, send email to >> kamaelia+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/kamaelia?hl=en. >> >> > -- You received this message because you are subscribed to the Google Groups "kamaelia" group. To post to this group, send email to kamae...@googlegroups.com. To unsubscribe from this group, send email to kamaelia+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/kamaelia?hl=en.
