Gambit-list Janvier 2009

gambit-list@iro.umontreal.ca

27 participants
31 discussions

Edge triggered I/O with libevent
by Adam Langley 04 Avr '13

04 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 09 Jui '09

09 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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webapp
by lowly coder 01 Fév '09

01 Fév '09

hey all, i'm thinking of writing a webapp, the type generally written w/ ruby on rails; but with gambit scheme. given existing tools / termite, I wanted to see what suggestions people had (the frontend is mainly flash + asynch javascript based, the backend needs to run on ec2; I need some type of database, but I'm not particularly attached to mysql or postgresql) please tell me anything that may be useful thanks!

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Re: [gambit-list] webframework
by Marc Feeley 01 Fév '09

01 Fév '09

On 30-Jan-09, at 10:41 PM, lowlycoder wrote: > can i write web apps using jazz scheme? if so, please give me some > pointers. thanks! You can also try out the Gambit web-server example in examples/web- server and there is also a web server on the Gambit dumping grounds which implements cookies and server pages (http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Dumping_Grounds#Full_… ). Marc

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The future of Gambit
by Bradley Lucier 31 Jan '09

31 Jan '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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Passing heterogenous lists
by Alex Ryu 30 Jan '09

30 Jan '09

Hello all I have written a C program calling scheme to evaluate logical and arithmetical expressions. It seems to work okay for integers, but floats have me at a loss. Short description of problem: I have a char buffer of known length. I know that the first four bytes represent a float, the second an int, the third an int, and so on. What I would like to do is somehow get this data into the scheme part of my program, preferably in a list form. One way is to use sprintf() to do a crummy sort of conversion, put the results in a null-terminated string, and use with-input-from-string (thanks to Marc for showing me), but that is pretty unpleasant. Are there any better methods? I was thinking about using vectors, but I can't see how that would work. Thanks for your help Alex I suppose I could just pass all 120 arguments to eval_string and list-replace? That seems pretty tedious. Here is more-or-less the relevant part of what I have now (c-define (eval-string str) (char-string) char-string "eval_string" "extern" (catch-all-errors (lambda () (write-to-string (eval (list-replace from to (read-from-string str))))))) from is a list of tokens, to is a list of values.

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Gambit manual documentation now on the wiki
by Marc Feeley 30 Jan '09

30 Jan '09

In order to improve the accessibility of the documentation and allow anyone to easily extend it with comments, clarifications and examples I have uploaded most of the Gambit manual to the Gambit wiki. All the procedure and special form sections have their own page (in the "Documentation" namespace). The top of the page is the documentation from the Gambit manual and the bottom is for user comments. I have a script which scans the wiki pages to see if there are any modifications, so that these modifications can make their way back to the Gambit manual. To make this transfer easier note that the text on the wiki uses the same texinfo markup language that is used for the Gambit manual. Here is a page with a list of all the entries in the Documentation namespace: http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php?title=Special%3AAllpa… You will notice that some pages are formatted incorrectly or have missing links. I'll improve that at a later time. Nevertheless the documentation is quite readable in its present state. Feel free to improve the documentation and contribute comments so that other Gambit users may benefit! Marc

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Fwd: [r6rs-discuss] [Scheme Steering Committee announcements] Final reminder: Scheme Steering Committee registration ends early Monday morning
by Marc Feeley 29 Jan '09

29 Jan '09

If you care about the future of Scheme, please don't forget to register to vote for the election of the Scheme steering committee which will oversee the next standardization process. I'm a nominee and you can read my statement (and those of the other nominees) at http://www.r6rs.org/steering-committee/election/nominees.html . You have to register before this **monday** so don't delay! Marc Begin forwarded message: > From: Mitchell Wand <wand(a)ccs.neu.edu> > Date: January 29, 2009 4:53:36 PM EST (CA) > To: Scheme List <scheme-announcements(a)lists.ccs.neu.edu> > Subject: [r6rs-discuss] [Scheme Steering Committee announcements] > Final reminder: Scheme Steering Committee registration ends early > Monday morning > > One last reminder: > > The registration period for voting in the election for the Scheme > Language Steering Committee ends on > > Monday, February 2, 2009, at 12:00pm GMT. > > That's 700am EST for those of you in the US (and 400am PST for > Californians). > > So unless you are an early riser, skip some of the Super Bowl (it's > almost always a blowout anyhow), and go to > http://www.r6rs.org/steering-committee/election/announcement.html > and register to vote. > > And if you aren't watching the Super Bowl, you have no excuse !-) > > This is also the deadline for nominations for the Steering > Committee. The current list of nominees can be found at http://www.r6rs.org/steering-committee/election/nominees.html > . > > Let's make sure that the electorate is a good sample of the Scheme > community. > > --Mitch Wand > > _______________________________________________ > Scheme-announcements mailing list > Scheme-announcements(a)lists.ccs.neu.edu > https://lists.ccs.neu.edu/bin/listinfo/scheme-announcements > _______________________________________________ > r6rs-discuss mailing list > r6rs-discuss(a)lists.r6rs.org > http://lists.r6rs.org/cgi-bin/mailman/listinfo/r6rs-discuss

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Re: [gambit-list] Problem in thread-sleep! may be a poor implementation of the select system call
by David St-Hilaire 29 Jan '09

29 Jan '09

sorry, i forgot to cc to gambit-list... -------- Original Message -------- Subject: Re: [gambit-list] Problem in thread-sleep! may be a poor implementation of the select system call Date: Wed, 28 Jan 2009 15:32:48 -0500 From: David St-Hilaire <sthilaid(a)iro.umontreal.ca> To: vasil <vasil.s.d(a)gmail.com> References: <A0A8D9BC-D43D-4AF1-86E9-375B3E071BDF(a)iro.umontreal.ca> <498005AE.5040703(a)gmail.com> <25B6814E-EA7D-469A-A9A5-714B015E6A50(a)iro.umontreal.ca> <4980AC02.8010705(a)gmail.com> <AB1AC1EE-9D9D-416F-81B4-AB035A663DC0(a)iro.umontreal.ca> <4980B46A.5040602(a)gmail.com> vasil wrote: > Interpreted code shows average n about 9064 (peak value was 9193), > compiled code - 9210 (peak value was 9226). Hi all! Sorry for the late response... So, even after upgrading to the latest gambit-c version: dave@david-laptop ~/sources/gambit-sources $ git log | head -n 3 commit fd8910a5c8649c037be72ec3349ffe535f0a7cd1 Author: Marc Feeley <feeley(a)iro.umontreal.ca> Date: Wed Jan 28 11:33:16 2009 -0500 I still get the bad performances... dave@david-laptop ~/sources/gambit-sources $ gsi/gsi ~/toto.scm 102 dave@david-laptop ~/sources/gambit-sources $ gsc/gsc ~/toto.scm dave@david-laptop ~/sources/gambit-sources $ gsi/gsi ~/toto.o1 102 The toto.scm file is the example provided by Marc, with a (declare (not safe)) declartion added. I'm using the gentoo kernel 2.6.28-gentoo-r1. Vasil, what kernel did you used? Thank you for the help! David

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Gambit-list Janvier 2009