From Richard.Mortier@nottingham.ac.uk Tue Nov 01 18:26:58 2011 Received: from ppsw-51.csi.cam.ac.uk ([131.111.8.151]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RLJ34-0006gQ-8g (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 01 Nov 2011 18:26:58 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195374 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from thb-mta-19-tx.emailfiltering.com ([194.116.199.150]:38898 helo=thb-mta-19.emailfiltering.com) by ppsw-51.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.148]:25) with esmtp (csa=unknown) id 1RLJ2y-0008Fq-Y9 (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 01 Nov 2011 18:26:58 +0000 Received: from smtp1.nottingham.ac.uk ([128.243.44.4]) by thb-mta-19.emailfiltering.com with emfmta (version 4.8.5.36) vanilla id 2174443734 for cl-mirage@lists.cam.ac.uk; 4f13af5089899640; Tue, 01 Nov 2011 18:26:32 +0000 Received: from uiwexhub02.ad.nottingham.ac.uk ([128.243.15.132]) by smtp1.nottingham.ac.uk with esmtp (Exim 4.60) (envelope-from ) id 1RLJ2e-0002bB-6K for cl-mirage@lists.cam.ac.uk; Tue, 01 Nov 2011 18:26:32 +0000 Received: from EXCHANGE1.ad.nottingham.ac.uk ([fe80::7962:f868:e6ee:6267]) by UIWEXHUB02.ad.nottingham.ac.uk ([2002:80f3:f84::80f3:f84]) with mapi; Tue, 1 Nov 2011 18:27:40 +0000 From: Richard Mortier To: Anil Madhavapeddy Date: Tue, 1 Nov 2011 18:26:30 +0000 Subject: sockets exn- one day i'll learn to put things down Thread-Topic: sockets exn- one day i'll learn to put things down Thread-Index: AcyYw++ShziGenztSdykVUqtLqU4OQ== Message-ID: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Nov 2011 18:26:58 -0000 X-Keywords: X-UID: 122 Status: O Content-Length: 3673 Lines: 90 ok- so i patently failed to get on and do some real work. instead, continu= ed blundering my way through figuring out this occasional exception. this = is something of a brain dump. [[ cl-mirage: ocaml gods welcome to look at this! :) i've no real idea wha= t i'm doing. symptom is that, when running the mirage-tutorial on unix -- = osx to be precise -- after "some" page reloads, it fails with a fatal error= indicating an uncaught exception: Fatal error: exception Invalid_argument("Lwt.wakeup") ...any hints welcome; roughly how far i've managed to get is below... ]] 1/ looks like cut'n'paste of c code unnecessary to get backtraces- followin= g patch appears to dtrt in terms of printing backtrace: """ : mort@greyjay:mirage.git$; git diff lib/os/unix/main.ml diff --git a/lib/os/unix/main.ml b/lib/os/unix/main.ml index 488d722..973d3ff 100644 --- a/lib/os/unix/main.ml +++ b/lib/os/unix/main.ml @@ -69,6 +69,7 @@ let run t =3D in (* Register a callback for the JS runtime to restart this function *) let _ =3D Callback.register "Main.run" fn in + Printexc.record_backtrace true; fn () =20 let () =3D at_exit (fun () -> run (call_hooks exit_hooks)) """ ... unless you know of a reason why that actually gives plausible looking g= arbage? 2/ my current impression is that we're waking up a thread that isn't actual= ly asleep. i'm basically clueless here - the exception appears to be being= thrown somewhere in std/format.ml and/or std/lwt.ml, eg., """ [00009] 2011/10/01T16:33:32Z info Server: /slides.js (backtr= ace: Raised at file "net/socket/channel.ml", line 129, characters 16-121 ) Fatal error: exception Invalid_argument("Lwt.wakeup") Raised at file "std/format.ml", line 195, characters 15-26 Called from file "std/format.ml", line 421, characters 8-33 Called from file "std/format.ml", line 436, characters 6-24 Called from file "std/lwt.ml", line 427, characters 66-71 Re-raised at file "std/lwt.ml", line 485, characters 33-36 Called from file "std/lwt.ml", line 147, characters 2-34 Called from file "std/lwt.ml", line 147, characters 2-34 ...many many repeats of line above... Called from file "std/lwt.ml", line 147, characters 2-34 Called from file "std/lwt.ml", line 130, characters 8-15 Called from file "std/lwt.ml", line 147, characters 2-34 make: *** [run-socket_fs] Error 2 """ the exn in channel.ml is the Closed exn raised to indicate file closure, an= d correctly handled. the exn in format.ml appears to come from parsing the format string, possib= ly reaching the end. after adding some extra debug output, the exn in lwt.ml is trying to wakup = a thread that's already in state "Return" any suggestions? 3/ in general, is there a well-known good setup for debugging this stuff? = useful compiler flags? useful pretty printer functions for getting state o= ut on the console? --=20 Cheers, R. = This message and any attachment are intended solely for the addressee a= nd may contain confidential information. If you have received this mess= age in error, please send it back to me, and immediately delete it. P= lease do not use, copy or disclose the information contained in this me= ssage or in any attachment. Any views or opinions expressed by the aut= hor of this email do not necessarily reflect the views of the Universit= y of Nottingham.=0D=0A=0D=0AThis message has been checked for viruses b= ut the contents of an attachment=0D=0Amay still contain software viruse= s which could damage your computer system:=0D=0Ayou are advised to perf= orm your own checks. Email communications with the=0D=0AUniversity of N= ottingham may be monitored as permitted by UK legislation.= From anil@recoil.org Tue Nov 01 18:42:14 2011 Received: from ppsw-52.csi.cam.ac.uk ([131.111.8.152]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RLJHq-0007IG-2t (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 01 Nov 2011 18:42:14 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195374 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:32772 helo=dark.recoil.org) by ppsw-52.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.149]:25) with smtp (csa=unknown) id 1RLJHp-0003LI-Eq (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 01 Nov 2011 18:42:14 +0000 Received: (qmail 25360 invoked by uid 634); 1 Nov 2011 18:42:13 -0000 X-Spam-Level: * X-Spam-Status: No, hits=-1.4 required=5.0 tests=ALL_TRUSTED X-Spam-Check-By: dark.recoil.org Received: from freak-0.srg.cl.cam.ac.uk (HELO freak-0.srg.cl.cam.ac.uk) (128.232.32.220) (smtp-auth username remote@recoil.org, mechanism cram-md5) by dark.recoil.org (qpsmtpd/0.83) with ESMTPA; Tue, 01 Nov 2011 18:42:11 +0000 Subject: Re: sockets exn- one day i'll learn to put things down Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Anil Madhavapeddy In-Reply-To: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> Date: Tue, 1 Nov 2011 18:42:10 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> To: Richard Mortier X-Mailer: Apple Mail (2.1251.1) X-Virus-Checked: Checked by ClamAV on dark.recoil.org Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Nov 2011 18:42:14 -0000 X-Keywords: X-UID: 123 Status: O Content-Length: 4875 Lines: 123 Firstly, lets add the record backtrace to the main function; very = useful! On the Lwt front, you are hitting the fact that the backtrace is lost = between threads due to the Lwt monad. However, the pa_lwt syntax = extension has an option to preserve the backtrace. I haven't turned = this on due to a certain difficulty with figuring out how to make it = optional in ocamlbuild.=20 However, I could just turn it on permanently, with us remembering to = turn it off when doing performance tests for production runs, where = thread backtrace recording may be too expensive. Any objections to that? On the general topic of debugging, what we really need is an interactive = toplevel. Lwt itself has a fantastic one if you install the Debian = package (lwt-toplevel) which could let you inspect the state of threads = as it runs. This is something that could be ported to Mirage at some = point... there's even a native code version of the toplevel now, so the = Xen backend could get in on the party too! Anil On 1 Nov 2011, at 18:26, Richard Mortier wrote: > ok- so i patently failed to get on and do some real work. instead, = continued blundering my way through figuring out this occasional = exception. this is something of a brain dump. >=20 > [[ cl-mirage: ocaml gods welcome to look at this! :) i've no real = idea what i'm doing. symptom is that, when running the mirage-tutorial = on unix -- osx to be precise -- after "some" page reloads, it fails with = a fatal error indicating an uncaught exception: >=20 > Fatal error: exception Invalid_argument("Lwt.wakeup") >=20 > ...any hints welcome; roughly how far i've managed to get is below... > ]] >=20 > 1/ looks like cut'n'paste of c code unnecessary to get backtraces- = following patch appears to dtrt in terms of printing backtrace: >=20 > """ > : mort@greyjay:mirage.git$; git diff lib/os/unix/main.ml > diff --git a/lib/os/unix/main.ml b/lib/os/unix/main.ml > index 488d722..973d3ff 100644 > --- a/lib/os/unix/main.ml > +++ b/lib/os/unix/main.ml > @@ -69,6 +69,7 @@ let run t =3D > in > (* Register a callback for the JS runtime to restart this function = *) > let _ =3D Callback.register "Main.run" fn in > + Printexc.record_backtrace true; > fn () >=20 > let () =3D at_exit (fun () -> run (call_hooks exit_hooks)) > """ > ... unless you know of a reason why that actually gives plausible = looking garbage? >=20 > 2/ my current impression is that we're waking up a thread that isn't = actually asleep. i'm basically clueless here - the exception appears to = be being thrown somewhere in std/format.ml and/or std/lwt.ml, eg., >=20 > """ > [00009] 2011/10/01T16:33:32Z info Server: /slides.js = (backtrace: Raised at file "net/socket/channel.ml", line 129, characters = 16-121 > ) > Fatal error: exception Invalid_argument("Lwt.wakeup") > Raised at file "std/format.ml", line 195, characters 15-26 > Called from file "std/format.ml", line 421, characters 8-33 > Called from file "std/format.ml", line 436, characters 6-24 > Called from file "std/lwt.ml", line 427, characters 66-71 > Re-raised at file "std/lwt.ml", line 485, characters 33-36 > Called from file "std/lwt.ml", line 147, characters 2-34 > Called from file "std/lwt.ml", line 147, characters 2-34 > ...many many repeats of line above... > Called from file "std/lwt.ml", line 147, characters 2-34 > Called from file "std/lwt.ml", line 130, characters 8-15 > Called from file "std/lwt.ml", line 147, characters 2-34 > make: *** [run-socket_fs] Error 2 > """ >=20 > the exn in channel.ml is the Closed exn raised to indicate file = closure, and correctly handled. >=20 > the exn in format.ml appears to come from parsing the format string, = possibly reaching the end. >=20 > after adding some extra debug output, the exn in lwt.ml is trying to = wakup a thread that's already in state "Return" >=20 > any suggestions? >=20 > 3/ in general, is there a well-known good setup for debugging this = stuff? useful compiler flags? useful pretty printer functions for = getting state out on the console? > --=20 > Cheers, >=20 > R. >=20 > This message and any attachment are intended solely for the addressee = and may contain confidential information. If you have received this = message in error, please send it back to me, and immediately delete it. = Please do not use, copy or disclose the information contained in this = message or in any attachment. Any views or opinions expressed by the = author of this email do not necessarily reflect the views of the = University of Nottingham. >=20 > This message has been checked for viruses but the contents of an = attachment > may still contain software viruses which could damage your computer = system: > you are advised to perform your own checks. Email communications with = the > University of Nottingham may be monitored as permitted by UK = legislation. From jac22@cl.cam.ac.uk Wed Nov 02 12:43:14 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RLa9y-0005ri-K9 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 12:43:14 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -4.1 from SpamAssassin-3.3.2-1195874 * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * -1.2 RP_MATCHES_RCVD Envelope sender domain matches handover relay * domain * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from mta1.cl.cam.ac.uk ([128.232.25.21]:43124) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with esmtp id 1RLa9y-0000Sx-py (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 12:43:14 +0000 Received: from ramsey.cl.cam.ac.uk ([128.232.1.219] helo=cl.cam.ac.uk) by mta1.cl.cam.ac.uk with esmtp (Exim 4.63) (envelope-from ) id 1RLa9y-0002Op-2p for cl-mirage@lists.cam.ac.uk; Wed, 02 Nov 2011 12:43:14 +0000 To: Mirage List Subject: not very mirage but related MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <30706.1320237791.1@cl.cam.ac.uk> Date: Wed, 02 Nov 2011 12:43:11 +0000 From: Jon Crowcroft Message-Id: X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Nov 2011 12:43:14 -0000 X-Keywords: X-UID: 124 Status: O Content-Length: 267 Lines: 13 i really like this paper Darjeeling, a feature-rich VM for the resource poor Niels Brouwers, Koen Langendoen, Peter Corke http://dl.acm.org/citation.cfm?id=1644056 or http://www.scribd.com/doc/46320830/2009-Brouwers-darjeeling seems not unrelated somehow jon From anil@recoil.org Wed Nov 02 13:09:59 2011 Received: from ppsw-41.csi.cam.ac.uk ([131.111.8.141]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RLaZr-0006qn-AC (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 13:09:59 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:35914 helo=dark.recoil.org) by ppsw-41.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.146]:25) with smtp (csa=unknown) id 1RLaZq-00086E-Qb (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 13:09:58 +0000 Received: (qmail 329 invoked by uid 634); 2 Nov 2011 13:09:57 -0000 X-Spam-Level: * X-Spam-Status: No, hits=-1.4 required=5.0 tests=ALL_TRUSTED X-Spam-Check-By: dark.recoil.org Received: from freak-0.srg.cl.cam.ac.uk (HELO freak-0.srg.cl.cam.ac.uk) (128.232.32.220) (smtp-auth username remote@recoil.org, mechanism cram-md5) by dark.recoil.org (qpsmtpd/0.83) with ESMTPA; Wed, 02 Nov 2011 13:09:57 +0000 Subject: Re: not very mirage but related Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Anil Madhavapeddy In-Reply-To: Date: Wed, 2 Nov 2011 13:09:56 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: <7CB7157D-DCA3-4FBD-808F-B371D7DFFDBF@recoil.org> References: To: Jon Crowcroft X-Mailer: Apple Mail (2.1251.1) X-Virus-Checked: Checked by ClamAV on dark.recoil.org Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Nov 2011 13:09:59 -0000 X-Keywords: X-UID: 125 Status: O Content-Length: 733 Lines: 27 Very neat! There's an OCaml project with similar goals: http://www.algo-prog.info/ocapic/web/index.php?id=3Docapic Runs the OCaml VM on a 16-bit PIC, nearly unmodified code. I've actually = got a half-finished tree that integrates its deadcode elimination into = Mirage, so our microkernels also benefit... will post that next week = after I finish some other paper work! Anil On 2 Nov 2011, at 12:43, Jon Crowcroft wrote: > i really like this paper > Darjeeling, a feature-rich VM for the resource poor > Niels Brouwers, Koen Langendoen, Peter Corke >=20 > http://dl.acm.org/citation.cfm?id=3D1644056 > or > http://www.scribd.com/doc/46320830/2009-Brouwers-darjeeling >=20 > seems not unrelated somehow >=20 > jon >=20 >=20 From Richard.Mortier@nottingham.ac.uk Wed Nov 02 17:25:09 2011 Received: from ppsw-52.csi.cam.ac.uk ([131.111.8.152]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RLeYn-0003h1-O9 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 17:25:09 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from ixe-mta-19-tx.emailfiltering.com ([194.116.198.150]:53092 helo=ixe-mta-19.emailfiltering.com) by ppsw-52.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.149]:25) with esmtp (csa=unknown) id 1RLeYh-0008Fh-DC (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 02 Nov 2011 17:25:09 +0000 Received: from smtp2.nottingham.ac.uk ([128.243.44.5]) by ixe-mta-19.emailfiltering.com with emfmta (version 4.8.5.36) vanilla id 2023499756 for cl-mirage@lists.cam.ac.uk; 4b6a9c9d6f1bef98; Wed, 02 Nov 2011 17:24:42 +0000 Received: from uiwexhub01.ad.nottingham.ac.uk ([128.243.15.133]) by smtp2.nottingham.ac.uk with esmtp (Exim 4.60) (envelope-from ) id 1RLeYM-0000Ei-PB for cl-mirage@lists.cam.ac.uk; Wed, 02 Nov 2011 17:24:42 +0000 Received: from EXCHANGE1.ad.nottingham.ac.uk ([fe80::7962:f868:e6ee:6267]) by UIWEXHUB01.ad.nottingham.ac.uk ([2002:80f3:f85::80f3:f85]) with mapi; Wed, 2 Nov 2011 17:25:50 +0000 From: Richard Mortier To: Anil Madhavapeddy Date: Wed, 2 Nov 2011 17:24:41 +0000 Subject: Re: sockets exn- one day i'll learn to put things down Thread-Topic: sockets exn- one day i'll learn to put things down Thread-Index: AcyZhHb4o1mdFD0vQdCNTEfKq6R89A== Message-ID: References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> In-Reply-To: <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Nov 2011 17:25:09 -0000 X-Keywords: X-UID: 126 Status: O Content-Length: 2145 Lines: 48 On 1 Nov 2011, at 18:42, Anil Madhavapeddy wrote: > Firstly, lets add the record backtrace to the main function; very useful! pull request sent :) > On the Lwt front, you are hitting the fact that the backtrace is lost bet= ween threads due to the Lwt monad. However, the pa_lwt syntax extension has= an option to preserve the backtrace. I haven't turned this on due to a ce= rtain difficulty with figuring out how to make it optional in ocamlbuild.=20 >=20 > However, I could just turn it on permanently, with us remembering to turn= it off when doing performance tests for production runs, where thread back= trace recording may be too expensive. >=20 > Any objections to that? aha. i have no objections - i'll start making use of that now anyway. (pre= sume you mean passing -lwt-debug to camlp4 as noted at ?) > On the general topic of debugging, what we really need is an interactive = toplevel. Lwt itself has a fantastic one if you install the Debian package = (lwt-toplevel) which could let you inspect the state of threads as it runs.= This is something that could be ported to Mirage at some point... there's= even a native code version of the toplevel now, so the Xen backend could g= et in on the party too! hm- perhaps a challenge for after ofelia tutorial is written :) --=20 Cheers, R. = This message and any attachment are intended solely for the addressee a= nd may contain confidential information. If you have received this mess= age in error, please send it back to me, and immediately delete it. P= lease do not use, copy or disclose the information contained in this me= ssage or in any attachment. Any views or opinions expressed by the aut= hor of this email do not necessarily reflect the views of the Universit= y of Nottingham.=0D=0A=0D=0AThis message has been checked for viruses b= ut the contents of an attachment=0D=0Amay still contain software viruse= s which could damage your computer system:=0D=0Ayou are advised to perf= orm your own checks. Email communications with the=0D=0AUniversity of N= ottingham may be monitored as permitted by UK legislation.= From avsm@dark.recoil.org Fri Nov 04 09:40:05 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RMGFp-0006wc-5e (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 04 Nov 2011 09:40:05 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:13059 helo=dark.recoil.org) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with smtp (csa=unknown) id 1RMGFn-0006d5-rK (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 04 Nov 2011 09:40:05 +0000 Received: (qmail 16750 invoked by uid 10000); 4 Nov 2011 09:40:03 -0000 Date: Fri, 4 Nov 2011 09:40:03 +0000 From: Anil Madhavapeddy To: Richard Mortier Subject: Re: sockets exn- one day i'll learn to put things down Message-ID: <20111104094003.GB10177@dark.recoil.org> References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Nov 2011 09:40:05 -0000 X-Keywords: X-UID: 127 Status: O Content-Length: 974 Lines: 24 On Wed, Nov 02, 2011 at 05:24:41PM +0000, Richard Mortier wrote: > > > On the Lwt front, you are hitting the fact that the backtrace is lost > > between threads due to the Lwt monad. However, the pa_lwt syntax > > extension has an option to preserve the backtrace. I haven't turned > > this on due to a certain difficulty with figuring out how to make it > > optional in ocamlbuild. > > > > However, I could just turn it on permanently, with us remembering to > > turn it off when doing performance tests for production runs, where > > thread backtrace recording may be too expensive. > > > > Any objections to that? > > aha. i have no objections - i'll start making use of that now anyway. > (presume you mean passing -lwt-debug to camlp4 as noted at > ?) Yeah. Did it work if you just manually add it to ocamlbuild? I've not had a chance to try it yet. -- Anil Madhavapeddy http://anil.recoil.org From Richard.Mortier@nottingham.ac.uk Fri Nov 04 21:19:26 2011 Received: from ppsw-51.csi.cam.ac.uk ([131.111.8.151]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RMRAc-0004mO-Ky (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 04 Nov 2011 21:19:26 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from thb-mta-19-tx.emailfiltering.com ([194.116.199.150]:55218 helo=thb-mta-19.emailfiltering.com) by ppsw-51.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.148]:25) with esmtp (csa=unknown) id 1RMRAW-0001Ya-Ye (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 04 Nov 2011 21:19:26 +0000 Received: from smtp1.nottingham.ac.uk ([128.243.44.4]) by thb-mta-19.emailfiltering.com with emfmta (version 4.8.5.36) vanilla id 2179228958 for cl-mirage@lists.cam.ac.uk; 610683950cbf499b; Fri, 04 Nov 2011 21:19:00 +0000 Received: from uiwexhub01.ad.nottingham.ac.uk ([128.243.15.133]) by smtp1.nottingham.ac.uk with esmtp (Exim 4.60) (envelope-from ) id 1RMR92-0002Pn-AU for cl-mirage@lists.cam.ac.uk; Fri, 04 Nov 2011 21:17:48 +0000 Received: from EXCHANGE1.ad.nottingham.ac.uk ([fe80::7962:f868:e6ee:6267]) by UIWEXHUB01.ad.nottingham.ac.uk ([2002:80f3:f85::80f3:f85]) with mapi; Fri, 4 Nov 2011 21:17:52 +0000 From: Richard Mortier To: Anil Madhavapeddy , Mirage List Date: Fri, 4 Nov 2011 21:16:43 +0000 Subject: Re: sockets exn- one day i'll learn to put things down Thread-Topic: sockets exn- one day i'll learn to put things down Thread-Index: AcybNzXcWfQMgrSfTDCjKEdxwsUYjQ== Message-ID: References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> <20111104094003.GB10177@dark.recoil.org> In-Reply-To: <20111104094003.GB10177@dark.recoil.org> Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Nov 2011 21:19:26 -0000 X-Keywords: X-UID: 128 Status: O Content-Length: 3172 Lines: 87 On 4 Nov 2011, at 09:40, Anil Madhavapeddy wrote: > On Wed, Nov 02, 2011 at 05:24:41PM +0000, Richard Mortier wrote: >> aha. i have no objections - i'll start making use of that now anyway. >> (presume you mean passing -lwt-debug to camlp4 as noted at >> ?) >=20 > Yeah. Did it work if you just manually add it to ocamlbuild? I've not had > a chance to try it yet. i *think* so... to summarise: + i've sent (or will send shortly) another pull req as i forgot to commit t= he addition of "-g" to ocamlc commands (required to actually have the backt= races filled in) + adding -lwt-debug to all builds changes the backtrace output i see to: """ Fatal error: exception Invalid_argument("Lwt.wakeup") Raised at file "std/format.ml", line 195, characters 15-26 Called from file "std/format.ml", line 421, characters 8-33 Called from file "std/format.ml", line 436, characters 6-24 Called from file "std/lwt.ml", line 922, characters 66-71 Re-raised at file "net/socket/flow.ml", line 51, characters 2-287 Re-raised at file "std/lwt.ml", line 485, characters 33-36 Called from file "std/lwt.ml", line 147, characters 2-34 Called from file "std/lwt.ml", line 147, characters 2-34 ... """ the reason i say "i think so" above is, surely i should see more detail tha= n that with debugging turned on? (though checking line numbers, it is the = backtrace_* versions of lwt bind etc that are being called.) + anyway, investigating flow.ml around line 51 i see: """ let close t =3D R.close t.fd; Lwt.wakeup t.abort_u (); return () let close_on_exit t fn =3D try_lwt=20 lwt x =3D fn t in close t=20 >> return x with exn ->=20 close t >> fail exn """ where line 51 is the "lwt x =3D ...". now, that looks suspicious to me- if an exception is raised in the initial = call of close then won't this attempt to wakeup the abort_u thread twice, l= eading to the Lwt.wakeup exception observed? =20 unfortunately, commenting out the try/catch sections doesn't solve the prob= lem, so i'll keep looking... any hints welcome- i'm getting this crash suf= ficiently frequently that i'd really prefer to fix it before the tutorial n= ext week... --=20 Cheers, R. i apologise for the rather long and pointless legalese that usually follows= - i have no control over this. it embarrasses me as much as it irritates y= ou... = This message and any attachment are intended solely for the addressee a= nd may contain confidential information. If you have received this mess= age in error, please send it back to me, and immediately delete it. P= lease do not use, copy or disclose the information contained in this me= ssage or in any attachment. Any views or opinions expressed by the aut= hor of this email do not necessarily reflect the views of the Universit= y of Nottingham.=0D=0A=0D=0AThis message has been checked for viruses b= ut the contents of an attachment=0D=0Amay still contain software viruse= s which could damage your computer system:=0D=0Ayou are advised to perf= orm your own checks. Email communications with the=0D=0AUniversity of N= ottingham may be monitored as permitted by UK legislation.= From anil@recoil.org Sat Nov 05 00:04:32 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RMTkO-0007QG-Fz (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Sat, 05 Nov 2011 00:04:32 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:4348 helo=dark.recoil.org) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with smtp (csa=unknown) id 1RMTkN-0007NT-rU (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Sat, 05 Nov 2011 00:04:32 +0000 Received: (qmail 32260 invoked by uid 634); 5 Nov 2011 00:04:31 -0000 X-Spam-Level: * X-Spam-Status: No, hits=-1.4 required=5.0 tests=ALL_TRUSTED X-Spam-Check-By: dark.recoil.org Received: from cpc2-belf1-0-0-cust23.2-1.cable.virginmedia.com (HELO [10.0.1.14]) (82.29.224.24) (smtp-auth username remote@recoil.org, mechanism cram-md5) by dark.recoil.org (qpsmtpd/0.83) with ESMTPA; Sat, 05 Nov 2011 00:04:31 +0000 Subject: Re: sockets exn- one day i'll learn to put things down Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Anil Madhavapeddy In-Reply-To: Date: Sat, 5 Nov 2011 00:04:28 +0000 Content-Transfer-Encoding: 7bit Message-Id: References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> <20111104094003.GB10177@dark.recoil.org> To: Richard Mortier X-Mailer: Apple Mail (2.1251.1) X-Virus-Checked: Checked by ClamAV on dark.recoil.org Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Nov 2011 00:04:32 -0000 X-Keywords: X-UID: 129 Status: O Content-Length: 328 Lines: 20 On 4 Nov 2011, at 21:16, Richard Mortier wrote: > let close t = > R.close t.fd; > Lwt.wakeup t.abort_u (); > return () > The try/catch would need to go locally here; can you try let close t = R.close t.fd; (try Lwt.wakeup t.abort_u () with _ -> ()); return () This should make multiple close() calls safe. Anil From Richard.Mortier@nottingham.ac.uk Sat Nov 05 08:49:26 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RMbwM-0006Gt-58 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Sat, 05 Nov 2011 08:49:26 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from ixe-mta-19-tx.emailfiltering.com ([194.116.198.150]:43672 helo=ixe-mta-19.emailfiltering.com) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with esmtp (csa=unknown) id 1RMbwG-0007W5-s4 (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Sat, 05 Nov 2011 08:49:26 +0000 Received: from smtp1.nottingham.ac.uk ([128.243.44.4]) by ixe-mta-19.emailfiltering.com with emfmta (version 4.8.5.36) vanilla id 2026504340 for cl-mirage@lists.cam.ac.uk; 4310feed0aaee424; Sat, 05 Nov 2011 08:49:00 +0000 Received: from uiwexhub01.ad.nottingham.ac.uk ([128.243.15.133]) by smtp1.nottingham.ac.uk with esmtp (Exim 4.60) (envelope-from ) id 1RMbvJ-0005E3-6I for cl-mirage@lists.cam.ac.uk; Sat, 05 Nov 2011 08:48:21 +0000 Received: from EXCHANGE1.ad.nottingham.ac.uk ([fe80::7962:f868:e6ee:6267]) by UIWEXHUB01.ad.nottingham.ac.uk ([2002:80f3:f85::80f3:f85]) with mapi; Sat, 5 Nov 2011 08:47:47 +0000 From: Richard Mortier To: Anil Madhavapeddy Date: Sat, 5 Nov 2011 08:46:38 +0000 Subject: Re: sockets exn- one day i'll learn to put things down Thread-Topic: sockets exn- one day i'll learn to put things down Thread-Index: Acybl5cr70FkBMx8Qoir6BK6ZMKizA== Message-ID: <05566CBD-3E60-4BD0-80BF-78F43E91388C@nottingham.ac.uk> References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> <20111104094003.GB10177@dark.recoil.org> In-Reply-To: Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Nov 2011 08:49:26 -0000 X-Keywords: X-UID: 130 Status: O Content-Length: 1697 Lines: 44 On 5 Nov 2011, at 00:04, Anil Madhavapeddy wrote: > The try/catch would need to go locally here; can you try >=20 > let close t =3D > R.close t.fd; > (try Lwt.wakeup t.abort_u () with _ -> ()); > return () >=20 > This should make multiple close() calls safe. done- pull req sent, both for this fix and modifications to enable turning = on/off lwt-debug. seems to fix the crashes i've been observing, which is nice :) though i'm = still a little disconcerted as to what was actually causing it- the debug o= utput i had in place suggested it wasn't getting called twice due to the ex= n handler. (but that might be my debug output coming out in an unexpected = order.) anyway- back to content production i guess ;) --=20 Cheers, R. i apologise for the rather long and pointless legalese that usually follows= - i have no control over this. it embarrasses me as much as it irritates y= ou... = This message and any attachment are intended solely for the addressee a= nd may contain confidential information. If you have received this mess= age in error, please send it back to me, and immediately delete it. P= lease do not use, copy or disclose the information contained in this me= ssage or in any attachment. Any views or opinions expressed by the aut= hor of this email do not necessarily reflect the views of the Universit= y of Nottingham.=0D=0A=0D=0AThis message has been checked for viruses b= ut the contents of an attachment=0D=0Amay still contain software viruse= s which could damage your computer system:=0D=0Ayou are advised to perf= orm your own checks. Email communications with the=0D=0AUniversity of N= ottingham may be monitored as permitted by UK legislation.= From avsm@dark.recoil.org Tue Nov 08 10:35:23 2011 Received: from ppsw-41.csi.cam.ac.uk ([131.111.8.141]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RNj1X-0002IB-O6 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 08 Nov 2011 10:35:23 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:9880 helo=dark.recoil.org) by ppsw-41.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.146]:25) with smtp (csa=unknown) id 1RNj1X-00073F-Qo (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Tue, 08 Nov 2011 10:35:23 +0000 Received: (qmail 7781 invoked by uid 10000); 8 Nov 2011 10:35:23 -0000 Date: Tue, 8 Nov 2011 10:35:23 +0000 From: Anil Madhavapeddy To: Richard Mortier Subject: Re: sockets exn- one day i'll learn to put things down Message-ID: <20111108103522.GA21522@dark.recoil.org> References: <6A87E742-82F2-479A-A587-309D2143CF4E@nottingham.ac.uk> <7691AA1C-3B04-4FDF-8983-91538CAC4313@recoil.org> <20111104094003.GB10177@dark.recoil.org> <05566CBD-3E60-4BD0-80BF-78F43E91388C@nottingham.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05566CBD-3E60-4BD0-80BF-78F43E91388C@nottingham.ac.uk> User-Agent: Mutt/1.5.20 (2009-06-14) Cc: Mirage List X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Nov 2011 10:35:23 -0000 X-Keywords: X-UID: 131 Status: O Content-Length: 1120 Lines: 32 On Sat, Nov 05, 2011 at 08:46:38AM +0000, Richard Mortier wrote: > > On 5 Nov 2011, at 00:04, Anil Madhavapeddy wrote: > > > The try/catch would need to go locally here; can you try > > > > let close t = > > R.close t.fd; > > (try Lwt.wakeup t.abort_u () with _ -> ()); > > return () > > > > This should make multiple close() calls safe. > > done- pull req sent, both for this fix and modifications to enable > turning on/off lwt-debug. Thanks, merged! Very handy to have this... > seems to fix the crashes i've been observing, which is nice :) though > i'm still a little disconcerted as to what was actually causing it- the > debug output i had in place suggested it wasn't getting called twice due > to the exn handler. (but that might be my debug output coming out in an > unexpected order.) Its somewhat complicated by libev; at some point, I'm going to take a look at removing libev and (maybe) integrating the system that node.js uses (libuv). For now though, it works well enough to not make it worth the trouble. I've updated the live website and it seems to have to stopped crashing too! Anil From h.rotsos@gmail.com Fri Nov 11 09:35:24 2011 Received: from ppsw-51.csi.cam.ac.uk ([131.111.8.151]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1ROnW8-0004E0-4k (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 11 Nov 2011 09:35:24 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -2.6 from SpamAssassin-3.3.2-1195874 * -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low * trust * [209.85.212.51 listed in list.dnswl.dnsbl.ja.net] * 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider * (h.rotsos[at]gmail.com) * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily * valid * -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from mail-vw0-f51.google.com ([209.85.212.51]:62711) by ppsw-51.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.148]:25) with esmtp (csa=unknown) id 1ROnW6-0000BE-XW (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 11 Nov 2011 09:35:23 +0000 Received: by vwl15 with SMTP id 15so3654025vwl.38 for ; Fri, 11 Nov 2011 01:35:21 -0800 (PST) MIME-Version: 1.0 Received: by 10.229.42.8 with SMTP id q8mr1709693qce.51.1321004121670; Fri, 11 Nov 2011 01:35:21 -0800 (PST) Sender: h.rotsos@gmail.com Received: by 10.229.242.70 with HTTP; Fri, 11 Nov 2011 01:35:21 -0800 (PST) Date: Fri, 11 Nov 2011 09:35:21 +0000 X-Google-Sender-Auth: mxuMurw1YxX3cDD2-ppw31DPDeQ Message-ID: Subject: wildcard match like comparison in ocaml From: Haris Rotsos To: "cl-mirage@lists.cam.ac.uk Mailing List" Content-Type: text/plain; charset=UTF-8 X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Nov 2011 09:35:24 -0000 X-Keywords: X-UID: 132 Status: O Content-Length: 605 Lines: 25 Hi all, I have a quick question regarding pattern matching in ocaml. I am interested for a module that can perform multiple wildcarded pattern matches in parallel in an efficient way. In routers a mechanism to achieve such functionality is to use a trie structure or a tcam. Are you aware of any readily available modules in ocaml that implements such fucntionality. thanks in advance for tips/pointers, -- Charalampos Rotsos PhD student The University of Cambridge Computer Laboratory William Gates Building JJ Thomson Avenue Cambridge CB3 0FD Phone: +44-(0) 1223 767032 Email: cr409@cl.cam.ac.uk From anil@recoil.org Fri Nov 11 10:16:54 2011 Received: from ppsw-41.csi.cam.ac.uk ([131.111.8.141]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1ROoAI-0007A6-F2 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 11 Nov 2011 10:16:54 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:46472 helo=dark.recoil.org) by ppsw-41.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.146]:25) with smtp (csa=unknown) id 1ROoAG-00004w-SU (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Fri, 11 Nov 2011 10:16:54 +0000 Received: (qmail 640 invoked by uid 634); 11 Nov 2011 10:16:52 -0000 X-Spam-Level: * X-Spam-Status: No, hits=-1.4 required=5.0 tests=ALL_TRUSTED X-Spam-Check-By: dark.recoil.org Received: from freak-0.srg.cl.cam.ac.uk (HELO [192.168.2.8]) (128.232.32.220) (smtp-auth username remote@recoil.org, mechanism cram-md5) by dark.recoil.org (qpsmtpd/0.83) with ESMTPA; Fri, 11 Nov 2011 10:16:47 +0000 Subject: Re: wildcard match like comparison in ocaml Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Anil Madhavapeddy In-Reply-To: Date: Fri, 11 Nov 2011 10:16:44 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Haris Rotsos X-Mailer: Apple Mail (2.1251.1) X-Virus-Checked: Checked by ClamAV on dark.recoil.org Cc: "cl-mirage@lists.cam.ac.uk Mailing List" X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Nov 2011 10:16:54 -0000 X-Keywords: X-UID: 133 Status: O Content-Length: 1108 Lines: 41 There's quite a few out there. You could grab the one locally in Mirage, = which is currently specialised for DNS lookups (a 256-way one) https://github.com/avsm/mirage/blob/master/lib/dns/dnstrie.ml Alternatively, there's a general one here: http://www.lri.fr/~filliatr/ftp/ocaml/ds/trie.ml.html Both are pretty small so you should be able to customise/tweak them as = needed... -anil On 11 Nov 2011, at 09:35, Haris Rotsos wrote: > Hi all, >=20 > I have a quick question regarding pattern matching in ocaml. I am > interested for a module that can perform multiple wildcarded pattern > matches in parallel in an efficient way. In routers a mechanism to > achieve such functionality is to use a trie structure or a tcam. Are > you aware of any readily available modules in ocaml that implements > such fucntionality. >=20 > thanks in advance for tips/pointers, >=20 >=20 > --=20 > Charalampos Rotsos > PhD student > The University of Cambridge > Computer Laboratory > William Gates Building > JJ Thomson Avenue > Cambridge > CB3 0FD >=20 > Phone: +44-(0) 1223 767032 > Email: cr409@cl.cam.ac.uk >=20 From h.rotsos@gmail.com Wed Nov 16 10:29:06 2011 Received: from ppsw-41.csi.cam.ac.uk ([131.111.8.141]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RQcjq-00029e-2q (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 10:29:06 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -2.6 from SpamAssassin-3.3.2-1195874 * -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low * trust * [209.85.212.51 listed in list.dnswl.dnsbl.ja.net] * 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider * (h.rotsos[at]gmail.com) * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily * valid * -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from mail-vw0-f51.google.com ([209.85.212.51]:34062) by ppsw-41.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.146]:25) with esmtp (csa=unknown) id 1RQcjo-0006eL-QQ (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 10:29:06 +0000 Received: by vws8 with SMTP id 8so1104977vws.38 for ; Wed, 16 Nov 2011 02:29:03 -0800 (PST) MIME-Version: 1.0 Received: by 10.224.27.11 with SMTP id g11mr8202281qac.51.1321439343442; Wed, 16 Nov 2011 02:29:03 -0800 (PST) Sender: h.rotsos@gmail.com Received: by 10.229.242.70 with HTTP; Wed, 16 Nov 2011 02:29:03 -0800 (PST) Date: Wed, 16 Nov 2011 10:29:03 +0000 X-Google-Sender-Auth: LOswLcMTWNIykQOmqv59GFQR7jw Message-ID: Subject: micro second timestamps from a regression test progrsm From: Haris Rotsos To: "cl-mirage@lists.cam.ac.uk Mailing List" Content-Type: text/plain; charset=UTF-8 X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 10:29:06 -0000 X-Keywords: X-UID: 134 Status: O Content-Length: 417 Lines: 20 Hi all, i was wondering how I can get microsecond timestamps from a test progrm of the mirge library. I tried the Unix.gettimeofday, but the module is not include at compile time. Is there some other module I can use? -- Charalampos Rotsos PhD student The University of Cambridge Computer Laboratory William Gates Building JJ Thomson Avenue Cambridge CB3 0FD Phone: +44-(0) 1223 767032 Email: cr409@cl.cam.ac.uk From Richard.Mortier@nottingham.ac.uk Wed Nov 16 12:04:33 2011 Received: from ppsw-41.csi.cam.ac.uk ([131.111.8.141]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RQeED-0007Dz-PZ (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:04:33 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from ixe-mta-19-tx.emailfiltering.com ([194.116.198.150]:46781 helo=ixe-mta-19.emailfiltering.com) by ppsw-41.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.146]:25) with esmtp (csa=unknown) id 1RQeE8-0006Yv-Qz (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:04:33 +0000 Received: from smtp2.nottingham.ac.uk ([128.243.44.5]) by ixe-mta-19.emailfiltering.com with emfmta (version 4.8.5.36) vanilla id 2038377728 for cr409@cl.cam.ac.uk; ffbf049f29a664f1; Wed, 16 Nov 2011 12:03:41 +0000 Received: from uiwexhub02.ad.nottingham.ac.uk ([128.243.15.132]) by smtp2.nottingham.ac.uk with esmtp (Exim 4.60) (envelope-from ) id 1RQeCh-0008Ak-57; Wed, 16 Nov 2011 12:02:59 +0000 Received: from EXCHANGE1.ad.nottingham.ac.uk ([fe80::7962:f868:e6ee:6267]) by UIWEXHUB02.ad.nottingham.ac.uk ([2002:80f3:f84::80f3:f84]) with mapi; Wed, 16 Nov 2011 12:04:11 +0000 From: Richard Mortier To: Haris Rotsos Date: Wed, 16 Nov 2011 12:02:56 +0000 Subject: Re: micro second timestamps from a regression test progrsm Thread-Topic: micro second timestamps from a regression test progrsm Thread-Index: AcykV9UXYXiwM1P/R9G7lLMN+oo1GQ== Message-ID: References: In-Reply-To: Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "cl-mirage@lists.cam.ac.uk Mailing List" X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 12:04:33 -0000 X-Keywords: X-UID: 135 Status: O Content-Length: 1444 Lines: 46 ought to be pretty easy to add as a c extension to the unix-* backends (i t= hink- happy to be contradicted... :) On 16 Nov 2011, at 10:29, Haris Rotsos wrote: > Hi all, >=20 > i was wondering how I can get microsecond timestamps from a test > progrm of the mirge library. I tried the Unix.gettimeofday, but the > module is not include at compile time. Is there some other module I > can use? >=20 > --=20 > Charalampos Rotsos > PhD student > The University of Cambridge > Computer Laboratory > William Gates Building > JJ Thomson Avenue > Cambridge > CB3 0FD >=20 > Phone: +44-(0) 1223 767032 > Email: cr409@cl.cam.ac.uk >=20 --=20 Cheers, R. = This message and any attachment are intended solely for the addressee a= nd may contain confidential information. If you have received this mess= age in error, please send it back to me, and immediately delete it. P= lease do not use, copy or disclose the information contained in this me= ssage or in any attachment. Any views or opinions expressed by the aut= hor of this email do not necessarily reflect the views of the Universit= y of Nottingham.=0D=0A=0D=0AThis message has been checked for viruses b= ut the contents of an attachment=0D=0Amay still contain software viruse= s which could damage your computer system:=0D=0Ayou are advised to perf= orm your own checks. Email communications with the=0D=0AUniversity of N= ottingham may be monitored as permitted by UK legislation.= From h.rotsos@gmail.com Wed Nov 16 12:09:10 2011 Received: from ppsw-52.csi.cam.ac.uk ([131.111.8.152]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RQeIg-0007Sm-6U (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:09:10 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -2.6 from SpamAssassin-3.3.2-1195874 * -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low * trust * [209.85.161.179 listed in list.dnswl.dnsbl.ja.net] * 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider * (h.rotsos[at]gmail.com) * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily * valid * -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from mail-gx0-f179.google.com ([209.85.161.179]:63162) by ppsw-52.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.149]:25) with esmtp (csa=unknown) id 1RQeIe-0000Ed-EW (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:09:10 +0000 Received: by ggnq2 with SMTP id q2so5909159ggn.38 for ; Wed, 16 Nov 2011 04:09:07 -0800 (PST) MIME-Version: 1.0 Received: by 10.229.67.213 with SMTP id s21mr4746990qci.89.1321445347650; Wed, 16 Nov 2011 04:09:07 -0800 (PST) Sender: h.rotsos@gmail.com Received: by 10.229.242.70 with HTTP; Wed, 16 Nov 2011 04:09:07 -0800 (PST) In-Reply-To: References: Date: Wed, 16 Nov 2011 12:09:07 +0000 X-Google-Sender-Auth: rMacmGfFv56-jSry1kiVq9l4FMc Message-ID: Subject: Re: micro second timestamps from a regression test progrsm From: Haris Rotsos To: Richard Mortier Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: "cl-mirage@lists.cam.ac.uk Mailing List" X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 12:09:10 -0000 X-Keywords: X-UID: 136 Status: O Content-Length: 1843 Lines: 68 I found something at OS.Clock.time() (unit -> float). This I think binds back to the libc gettimeofday. On 16 November 2011 12:02, Richard Mortier wrote: > ought to be pretty easy to add as a c extension to the unix-* backends (i= think- happy to be contradicted... :) > > On 16 Nov 2011, at 10:29, Haris Rotsos wrote: > >> Hi all, >> >> i was wondering how I can get microsecond timestamps from a test >> progrm of the mirge library. I tried the Unix.gettimeofday, but the >> module is not include at compile time. Is there some other module I >> can use? >> >> -- >> Charalampos Rotsos >> PhD student >> The University of Cambridge >> Computer Laboratory >> William Gates Building >> JJ Thomson Avenue >> Cambridge >> CB3 0FD >> >> Phone: +44-(0) 1223 767032 >> Email: cr409@cl.cam.ac.uk >> > > -- > Cheers, > > R. > > > > This message and any attachment are intended solely for the addressee and= may contain confidential information. If you have received this message in= error, please send it back to me, and immediately delete it. =C2=A0 Please= do not use, copy or disclose the information contained in this message or = in any attachment. =C2=A0Any views or opinions expressed by the author of t= his email do not necessarily reflect the views of the University of Notting= ham. > > This message has been checked for viruses but the contents of an attachme= nt > may still contain software viruses which could damage your computer syste= m: > you are advised to perform your own checks. Email communications with the > University of Nottingham may be monitored as permitted by UK legislation. --=20 Charalampos Rotsos PhD student The University of Cambridge Computer Laboratory William Gates Building JJ Thomson Avenue Cambridge CB3 0FD Phone: +44-(0) 1223 767032 Email: cr409@cl.cam.ac.uk From robert.watson@cl.cam.ac.uk Wed Nov 16 12:12:20 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RQeLk-0007jd-79 (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:12:20 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from cyrus.watson.org ([65.122.17.42]:11008) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with esmtp (csa=unknown) id 1RQeLg-0000BH-s3 (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 12:12:20 +0000 Received: from c0166.aw.cl.cam.ac.uk (c0166.aw.cl.cam.ac.uk [128.232.100.166]) by cyrus.watson.org (Postfix) with ESMTPSA id B079B46B09; Wed, 16 Nov 2011 07:12:14 -0500 (EST) Subject: Re: micro second timestamps from a regression test progrsm Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: "Robert N. M. Watson" In-Reply-To: Date: Wed, 16 Nov 2011 12:12:13 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: <73EEBDDB-33D7-4180-BA74-EE55A2B6E94C@cl.cam.ac.uk> References: To: Haris Rotsos X-Mailer: Apple Mail (2.1084) Cc: Richard Mortier , "cl-mirage@lists.cam.ac.uk Mailing List" X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 12:12:20 -0000 X-Keywords: X-UID: 137 Status: O Content-Length: 748 Lines: 19 On 16 Nov 2011, at 12:09, Haris Rotsos wrote: > I found something at OS.Clock.time() (unit -> float). This I think > binds back to the libc gettimeofday. On the UNIX side, a good general piece of advice for accurate = time-keeping is to use clock_gettime() and name a high-accuracy clock. = You can also use clock_getres() to ask questions about the resolution of = the timestamps you get back. On FreeBSD, at least, you can request = accurate vs. fast using different clock names. Finally, asking for the = time of day is not quite the same as asking for elapsed time, so you = might or might not be interested in asking for a monotonic time source = instead of a time-of-day time source, depending on your goals and how = NTP feels. Robert From anil@recoil.org Wed Nov 16 13:30:44 2011 Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]) by lists-2.csi.cam.ac.uk (lists.cam.ac.uk [131.111.8.15]:25) with esmtp id 1RQfZc-0003mm-Rr (Exim 4.70) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 13:30:44 +0000 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: score -1.9 from SpamAssassin-3.3.2-1195874 * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from recoil.dh.bytemark.co.uk ([89.16.177.154]:32952 helo=dark.recoil.org) by ppsw-50.csi.cam.ac.uk (mx.cam.ac.uk [131.111.8.147]:25) with smtp (csa=unknown) id 1RQfZc-0007BI-r5 (Exim 4.72) for cl-mirage@lists.cam.ac.uk (return-path ); Wed, 16 Nov 2011 13:30:44 +0000 Received: (qmail 11962 invoked by uid 634); 16 Nov 2011 13:30:44 -0000 X-Spam-Level: * X-Spam-Status: No, hits=-1.4 required=5.0 tests=ALL_TRUSTED X-Spam-Check-By: dark.recoil.org Received: from host81-149-102-120.in-addr.btopenworld.com (HELO [192.168.0.18]) (81.149.102.120) (smtp-auth username remote@recoil.org, mechanism cram-md5) by dark.recoil.org (qpsmtpd/0.83) with ESMTPA; Wed, 16 Nov 2011 13:30:44 +0000 Subject: Re: micro second timestamps from a regression test progrsm Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Anil Madhavapeddy In-Reply-To: Date: Wed, 16 Nov 2011 13:30:42 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Haris Rotsos X-Mailer: Apple Mail (2.1251.1) X-Virus-Checked: Checked by ClamAV on dark.recoil.org Cc: Richard Mortier , "cl-mirage@lists.cam.ac.uk Mailing List" X-BeenThere: cl-mirage@lists.cam.ac.uk X-Mailman-Version: 2.1.8 Precedence: list List-Id: MirageOS development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2011 13:30:44 -0000 X-Keywords: X-UID: 138 Status: O Content-Length: 2288 Lines: 81 That's the correct call. It uses the Xen monotonic timer, or the UNIX = equivalent. This is current gettimeofday(), but could easily be upgraded = to a higher resolution timer on UNIX (as Robert suggests) if necessary = (which it isn't at the moment for your tests). Anil On 16 Nov 2011, at 12:09, Haris Rotsos wrote: > I found something at OS.Clock.time() (unit -> float). This I think > binds back to the libc gettimeofday. >=20 > On 16 November 2011 12:02, Richard Mortier > wrote: >> ought to be pretty easy to add as a c extension to the unix-* = backends (i think- happy to be contradicted... :) >>=20 >> On 16 Nov 2011, at 10:29, Haris Rotsos wrote: >>=20 >>> Hi all, >>>=20 >>> i was wondering how I can get microsecond timestamps from a test >>> progrm of the mirge library. I tried the Unix.gettimeofday, but the >>> module is not include at compile time. Is there some other module I >>> can use? >>>=20 >>> -- >>> Charalampos Rotsos >>> PhD student >>> The University of Cambridge >>> Computer Laboratory >>> William Gates Building >>> JJ Thomson Avenue >>> Cambridge >>> CB3 0FD >>>=20 >>> Phone: +44-(0) 1223 767032 >>> Email: cr409@cl.cam.ac.uk >>>=20 >>=20 >> -- >> Cheers, >>=20 >> R. >>=20 >>=20 >>=20 >> This message and any attachment are intended solely for the addressee = and may contain confidential information. If you have received this = message in error, please send it back to me, and immediately delete it. = Please do not use, copy or disclose the information contained in this = message or in any attachment. Any views or opinions expressed by the = author of this email do not necessarily reflect the views of the = University of Nottingham. >>=20 >> This message has been checked for viruses but the contents of an = attachment >> may still contain software viruses which could damage your computer = system: >> you are advised to perform your own checks. Email communications with = the >> University of Nottingham may be monitored as permitted by UK = legislation. >=20 >=20 >=20 > --=20 > Charalampos Rotsos > PhD student > The University of Cambridge > Computer Laboratory > William Gates Building > JJ Thomson Avenue > Cambridge > CB3 0FD >=20 > Phone: +44-(0) 1223 767032 > Email: cr409@cl.cam.ac.uk >=20