Décembre 2008 - Gambit-list - mailman.iro.umontreal.ca

Edge triggered I/O with libevent
by Adam Langley 05 Avr '13

05 Avr '13

Gambit uses the select call on POSIX systems to multiplex IO operations. This is fine for small numbers of file descriptors, but falls apart quickly with large numbers[1]. libevent[2] is a wrapper library around a number of modern IO multiplexing systems (epoll on Linux, kqueue on the BSDs as well as poll and select). Attached is a patch which converts Gambit to using edge triggered I/O with epoll and libevent. This also requires a patch (attached) of libevent since the standard distribution doesn't include edge triggering support and the upstream appears to be on holiday. (epoll is required because I don't have a BSD box on which to develop edge triggering support for kqueue) This patch (for Gambit) preprocesses away to nothing unless --enable-libevent is passed to the configure script. (Note that, since this patches the configure.ac script, you'll need to run autoconf to regenerate). I hope I've not broken anything, but at this stage I've only tested that the console and tcp ports work. This patch (in the future) should also allow people, who write programs which use socket calls directly, to integrate into the main event loop at some point. Testing is more than welcome and, if you find a form of IO which is broken, please email me. [1] http://monkey.org/~provos/libevent/libevent-benchmark2.jpg [2] http://monkey.org/~provos/libevent/ -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Interactive 3D graphics with Gambit-C
by Alex Sandro Queiroz e Silva 06 Jan '10

06 Jan '10

Hallo, I am thinking about doing some basic 3D graphics with Gambit-C. Although I am sure code generated by Gambit-C is fast enough[1], I am a bit worried about the garbage collector. What's the type of garbage collector used by Gambit? If it kicks in during interactive rendering, should I expect annoying pauses? [1] - http://www.ventonegro.org/2008/09/the-need-for-speed/ -alex http://www.ventonegro.org/

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I/O puzzle...
by Marc Feeley 10 Jui '09

10 Jui '09

Puzzle... what's the bug in the following code? See end of message for answer. (define http-server-start! (lambda (hs stop?) (let ((server-port (open-tcp-server (list port-number: (server-port-number hs) backlog: 128 reuse-address: #t server-address: '#u8(127 0 0 1) ; on localhost interface only char-encoding: 'ISO-8859-1)))) (input-port-timeout-set! server-port 3) (accept-connections hs server-port stop?)))) (define accept-connections (lambda (hs server-port stop?) (let loop () (let ((connection (read server-port))) (if (eof-object? connection) (if (stop?) (close-input-port server-port) (loop)) (begin (if (server-threaded? hs) (let ((dummy-port (open-dummy))) (parameterize ((current-input-port dummy-port) (current-output-port dummy-port)) (thread-start! (make-thread (lambda () (serve-connection hs connection)))))) (serve-connection hs connection)) (loop))))))) . . . . . . . . Answer: the (input-port-timeout-set! server-port 3) is at the wrong place. It sets a timeout ***3 seconds in the future***. So after 3 seconds have passed all calls to read in accept-connections will not block (and lead to a tight, CPU intensive loop). The correct approach is to put the call to (input-port-timeout-set! server-port 3) just before the call to read. Puzzle #2: why did Gambit chose to define timeouts that are not relative to the moment that an I/O function is called? Marc

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The future of Gambit
by Bradley Lucier 01 Fév '09

01 Fév '09

I've had a draft e-mail sitting in an IMAP folder for about 8 months with the subject line "The future of Gambit", but with an empty body. Today I still don't know precisely what to put into this body, but at least I found a blog entry that explains a bit of my feelings. I'm not exactly thrilled about the level of "outside" participation in (core) Gambit development. In fact, graphing the Gambit git commit log would be a parody of the argument in http://www.gnome.org/~michael/blog/ooo-commit-stats-2008.html that the lack of non-Sun developers working on OpenOffice.org is an indicator that it is not a healthy project. For there is only one committer to Gambit, and the best that can be said about getting other developers to develop code for Gambit is that a very few times Marc has committed code he hasn't written himself. I've studied the Gambit source code a bit, and even made some contributions over the years, but Marc's programming style is something I have not seen elsewhere---highly macroized and layered, there are patterns in the coding techniques but not ones that I've been able to unravel in general. Perhaps one way to help new developers get into Gambit would be fore Marc to take a subsystem and write down an explanation of how the macros and layers of code for types, exceptions, constructors, functions, ... of that subsystem work. (Christian Jaeger seems to have had some success in doing this, but it would be good to have an explanation of how Marc sees the construction of subsystems of the runtime.) Just to get an idea of Marc's programming style would allow others to divine more easily the structure of the code. And happy holidays to everyone! Brad

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[ANN] Gambit-C v4.4.0 released
by gambit＠iro.umontreal.ca 24 Déc '08

24 Déc '08

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PICBIT, PICOBIT, etc.
by Andrew Lentvorski 18 Déc '08

18 Déc '08

A while back, there was mumbling about releasing these. Did this ever come to fruition? A small Scheme might be a nice brainteaser to mull over during Christmas break. Thanks, -a

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cross-compilation for dummies
by Oisín Mac Fhearaí 15 Déc '08

15 Déc '08

Hi all, I'm fairly out of my depth here, trying to compile Gambit such that it will cross-compile (on OS X) and produce executables that will run on my old m68k-based Palm (err, actually ARM-based, but with some weird caveats that make it easier to use 68k). There doesn't seem to be any documentation on how to do such a thing, but grepping in the latest source release implies that it can be done via the "--host" configure option. With the following configure command: ./configure --prefix=/Users/oisin/code/palm/scheme/gambit/ --host=m68k-palmos --enable-ansi-c --enable-char-size=2 --enable-single-host (the enable-ansi-c and char-size=2 options were just a stab in the dark and neither help nor hinder) and the following make line (for wchar.h): C_INCLUDE_PATH=/Users/oisin/.wine/drive_c/PalmOSCygwin/usr/include/ make ...I get hundreds of thousands of errors like this, before the build gives up: /var/folders/ra/raN9YbS9GOKB9pULa-Z47E+++TI/-Tmp-/cc7yLvmh.s:193444: Error: Value of 716162 too large for field of 2 bytes at 0x81dfa /var/folders/ra/raN9YbS9GOKB9pULa-Z47E+++TI/-Tmp-/cc7yLvmh.s:193444: Error: Signed .word overflow; switch may be too large; 716162 at 0x81dfa ..... make[1]: *** [_io.o] Error 1 make: *** [all-recursive] Error 1 Maybe this is because the 68k only has a 16-bit word size. Does it mean that Gambit C can't be build to compile for the 68k, or is there a way to do it? thanks, Oisín

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Re: [gambit-list] cross-compilation for dummies
by Oisín Mac Fhearaí 14 Déc '08

14 Déc '08

Hey all, > Error: Value of 716162 too large for field of 2 bytes at 0x81dfa Actually on further inspection, it looks like the Palm architecture limits code segments to 64k max, and clearly the code Gambit C will produce is going to be unavoidably bigger. There's presumably some way of breaking it into multiple segments, but it seems like a right headache so I'll leave it for now. Sorry for the noise! Oisín

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Matrix and linear algebra
by David St-Hilaire 12 Déc '08

12 Déc '08

Hi all! I currently need some basic linear algebra manipulation. I could easily write it myself, but I'm sure that someone else has, already! hehe Has anyone such a library available (open source)? If so, is it possible to have it on the dumping grounds? Many Thanks!! David

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SRFIs for Gambit
by Christoph Bauer 11 Déc '08

11 Déc '08

Hi, in the wiki is a link to some SRFIs [1]. Previously it seems to work, but neither yesterday nor today. Is there a mirror/copy anywhere? Thanks, Christoph [1] http://bunny.jonnay.net/zengarden/trunk/lib/srfi-pack/

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