http://blog.gmane.org/gmane.comp.lang.erlang.general hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.comp.lang.erlang.general/33621 Hi, Anyone out there made some erlang examples working with MonetDB? using ODBC acceptable. Cheers, Bryan Rasmussen bryan rasmussen 2008-10-07T11:54:37 http://comments.gmane.org/gmane.comp.lang.erlang.general/33605 This is an interesting article that I've found when it comes to security that a programming language can provide. http://www.net-security.org/secworld.php?id=6619 By no means I'm trying to compare Ada to Erlang. There are far too many things to take into account. However, I would like to know just how well Erlang measures up to the features that are part of the Ada language which make it so predictable and secure. I'd love to hear some input from fellow Erlang programmers who have a background in Ada. YourSurrogateGod 2008-10-06T23:51:46 http://comments.gmane.org/gmane.comp.lang.erlang.general/33604 Tony Arcieri 2008-10-06T23:34:07 http://comments.gmane.org/gmane.comp.lang.erlang.general/33603 Hi, trawling through the archives I found the answer to how to do a ? FUNCTION macro. How would you do ?DATE and ?TIME (apart from erlc -DDATE=`time` .... or something similar, which is *nix specific) Would there be any mileage in adding these (and ?FUNCTION) to epp? Rgds, Matthew (aka Harry) harry 2008-10-06T21:17:01 http://comments.gmane.org/gmane.comp.lang.erlang.general/33593 Greg Burri 2008-10-06T14:17:55 http://comments.gmane.org/gmane.comp.lang.erlang.general/33580 Quviq provides a QuickCheck course before this years Erlang User Conference. The course will take place in Stockholm, November 10-12, 2008. The course is ment for Erlang developers interested in test driven development. The course consists of two and a half days with a mixture of theory and practical sessions, and includes a one month QuickCheck licence, which can be used to gain further experience with our tool after the course is over. November, 10: 9:00 - 17:00 Properties and generators, Symbolic test cases, Positive and negative testing. November, 11: 9:00 - 17:00 Testing stateful systems, Protocol testing. November 13: 9:00 - 13:00 Minimizing counter-examples. You can get more information and register for the course by email to thomas.arts< at >quviq.com. Registration is on a first come, first served basis and the number of seats is restricted to a maximum of 12. The price is 12 500 sek per participant. This price is excluding hotel costs. Participants are expected to book their hotel themselves. The course is given in collaboration with Sjöland&Thyselius. /Thomas Thomas Arts 2008-10-06T08:41:56 http://comments.gmane.org/gmane.comp.lang.erlang.general/33570 Hello, its me again... so I've been having this problem for days, with the bellow code. Most of it is straight out of the "Programming Erlang" book from Joe Armstrong... however when Im compiling it its telling me that the function data_process/1 is not being used, gives me a warning, but then still compiles. however when Im sending data from a client side via TCP ofcourse it exits on me because there's nothing to process the message... I HAVE NO IDEA WHAT'S WRONG WITH IT. I've read up on all the spawn_link() definitions and as far as I can tell Im using it correctly... the PiD that spawn_link() returns is being returned so it executes successfully. please help out, its stalling my project progress. thanks -module(tcp_manager). %API-------------------------------------------- -export([start/1]). %----------------------------------------------- start(Port) -> {ok, ListeningSocket} = gen_tcp:listen( Port, [ binary, %receive data in binary form {packet , 0}, {reuseaddr, true}, %hybrid - active for only one message %it auto-receives one message after which it blocks %has to be set to active-once again to receive the next message {active , once} ] ), accept_connection(ListeningSocket). %----------------------------------------------- accept_connection(ListeningSocket) -> io:format("waiting to accept~n"), {ok, Socket} = gen_tcp:accept(ListeningSocket), io:format("Socket is:~p~n", [Socket]), %----------------------------------------------- Listen_for_errors = fun() -> io:format("listening started~n"), receive {'EXIT', Pid, Why} -> io:format("~p exited because:~p", [Pid,Why]); Other -> io:format("Other:~p~n", [Other]) end end, Listen_for_errors(), %----------------------------------------------- Handler_process = spawn_link(?MODULE, data_process, [Socket]), %,[]]), io:format("handlers process ID:~p", [Handler_process]). accept_connection(ListeningSocket). %----------------------------------------------- data_process( Socket, DataSoFar) -> io:format("responder_loop() entered~n"), receive {tcp, Socket, Data} -> %Source_ip = inet:peername(Socket), %io:format("*~p - data coming in:~p~n",[Source_ip,Data]), io:format("works - Data:~p~n", [Data]), %has to be done, since its an active-once socket inet:setopts( Socket, [{active,once}] ), data_process( Socket, %append the new binary fragment to what has been received so far [Data | DataSoFar] ); {tcp_closed, Socket} -> io:format("*client socket closed~n"); %reverse because data has been appended to the head of the list as it was coming in list_to_binary(lists:reverse(SoFar)); Other -> io:format("undefined message came in:~p", [Other]) end. %----------------------------------------------- deepblue_other 2008-10-05T16:39:41 http://comments.gmane.org/gmane.comp.lang.erlang.general/33569 Michael Regen 2008-10-05T17:04:12 http://comments.gmane.org/gmane.comp.lang.erlang.general/33560 Today I sat down to try to make working with mochiweb a little cleaner for myself. I wanted a way to specify a list of mappings between url patterns and methods to be called with the matched variables from them. I quickly ran into issues with not being able to create patterns dynamically, and then tried using funs to wrap that functionality but pretty soon I was back at the same mess I started with. This is kind of my "if the world were perfect" module (that doesn't work at all but I hope might show what I was going for). I was hoping folks might help be think up some ways to handle use cases like this. -module(roto_web_routes). -export([ call/1 ]). -define(VIEWS_MODULE, roto_web_views). routes() -> [ url(["version"], version), url(["register"], register), url(["node", NodeName, "messages"], messages), url(["node", NodeName, "messages", Id], message), url(["node", NodeName, "messages"], subscriptions), url(["node", NodeName, "messages", Id], subscriptions) ]. url(Pattern, View) -> {route, Pattern, View, View}. url(Pattern, View, Name) -> {route, Pattern, View, Name}. % should take a request, find the matching url config and pass % the matched variables into the function specified in the url % config for that entry. call(Req) -> Path = string:tokens(Req:get(path), "/"), match_route(Path). match_route(Path) -> %does something fancy with routes() to get to the function % I want to call and call it with the matched variables ok. Thanks! ~ Anders anders conbere 2008-10-05T22:15:26 http://comments.gmane.org/gmane.comp.lang.erlang.general/33554 Folks, I run Mac OSX 10.5.5 on a Mac Pro 2x2.8Ghz Xeon, 14Gb of memory. Erlang (BEAM) emulator version 5.6.3 [source] [64-bit] [smp:8] [async- threads:2] [kernel-poll:true] I found that when I run everything on a single VM and launch 500 games everything runs through just fine. I then distributed my OpenPoker test harness over 3 VMs: one hosts Mnesia tables and launches games, one runs games and launches bots, one runs the bots. The last two VMs are added as extra Mnesia nodes, i.e. have RAM copies of tables. Here's is when I started getting player timeouts. Each player (bot actually) is supposed to make a bet within 15 seconds but a lot of bots fail to do so in a distributed configuration. Unlike my previous testing, I now launch all games at the same time. There are about 5 players per game so 500 games would make about 2500 player bots and the same amount of open sockets. Dumping core upon a player timeout reveals that most of queue lengths are 0, a lot of queues have just 1 message in them and two queues have 2 messages. I decided to time packets and measure the time it takes for a packet to travel from the server to the client and from the client to the server. This is where I got results that I can't quite explain... The time a packet travels from a server to the client is consistently greater by a large margin!!! Would someone kindly offer an explanation? Rather than adding timestamps to each individual packet, I send a ping packet right after any packet the server sends out. I do this from my tcpsend macro, i.e. -define(tcpsend(Socket, Data), fun() -> XXX = pp:write(Data), case catch gen_tcp:send(Socket, XXX) of ok -> ok; ... end, YYY = pp:write(#ping{}), case catch gen_tcp:send(Socket, YYY) of ok -> ok; ... end end()). The ping packet looks like this: -record(ping, { send_time = now() }). Once a bot receives the ping packet, it sends a pong back: handle_ping(R, Bot) -> handle_cast(#pong{ orig_send_time = R#ping.send_time }, Bot), {noreply, Bot}. Here I copy the original send time into the pong packet and stamp it with send time on the bot side: -record(pong, { orig_send_time, send_time = now(), recv_time }). Once my server receives the pong packet, it plugs receive time in: process_pong(Client, _Socket, R) -> R1 = R#pong{ recv_time = now() }, gen_server:cast(Client#client.server, {'PONG', R1}), Client. I measure the time to client by subtracting original send time from the bot send time. The bots are dumb, they reply back as quickly as possible and don't contain any logic so there's should be very little overhead on the bot side. The time to server is the difference between time of receipt on the server side and the bot send time. handle_cast({'PONG', R = #pong{}}, Server) -> TC = timer:now_diff(R#pong.send_time, R#pong.orig_send_time), TS = timer:now_diff(R#pong.recv_time, R#pong.send_time), gen_server:cast(?STATS, {'AVG', time_to_client, TC}), gen_server:cast(?STATS, {'AVG', time_to_server, TS}), {noreply, Server}; I have a separate "statistics" server that keeps track of averages: handle_cast({'AVG', Id, New}, Data) -> Old = case gb_trees:lookup(Id, Data#stats.avg) of {value, Val} -> Val; none -> 0 end, Avg1 = gb_trees:enter(Id, (Old + New) / 2, Data#stats.avg), {noreply, Data#stats{ avg = Avg1 }}; When dumping stats, I divide averages by 1000 to get time in milliseconds. So far so good? Here are the results from testing on a single VM. Note that at some point the time to server starts to exceed the time to client. Timings from testing on a cluster of 3 VMs follow at the bottom. --- single VM --- gateway:start('1< at >mothership', 4000, 500000) Waiting for game servers... Starting a port server on 4000... Simulating gameplay with 500 games... 50 games started, 262 players 100 games started, 504 players 150 games started, 743 players 200 games started, 1019 players 250 games started, 1288 players 300 games started, 1529 players 350 games started, 1766 players 400 games started, 2057 players 450 games started, 2304 players 500 games started, 2562 players dmb: 500 games launching simultaneously dmb: waiting for games to end... =INFO REPORT==== 6-Oct-2008::08:14:55 === module: stats elapsed: 5.000022 time_to_client: 0.3116982504004592 time_to_server: 0.26828120427789537 bytes: 110919 packets: 6202 {bytes,per_sec}: 22183 {packets,per_sec}: 1240 =INFO REPORT==== 6-Oct-2008::08:15:00 === module: stats elapsed: 4.999943 time_to_client: 0.335493890834141 time_to_server: 0.2682274480913192 bytes: 35447 packets: 1984 {bytes,per_sec}: 7089 {packets,per_sec}: 396 =INFO REPORT==== 6-Oct-2008::08:15:10 === module: stats elapsed: 4.999295 time_to_client: 0.8764044453192754 time_to_server: 0.5871947161189068 bytes: 600493 packets: 25147 {bytes,per_sec}: 120115 {packets,per_sec}: 5030 =INFO REPORT==== 6-Oct-2008::08:15:15 === module: stats elapsed: 5.000729 time_to_client: 0.416 time_to_server: 198.9885 bytes: 25 packets: 1 {bytes,per_sec}: 4 {packets,per_sec}: 0 =INFO REPORT==== 6-Oct-2008::08:15:25 === module: stats elapsed: 5.131727 time_to_client: 4.039440742060922 time_to_server: 44.38444315504353 bytes: 49034 packets: 1979 {bytes,per_sec}: 9555 {packets,per_sec}: 385 =INFO REPORT==== 6-Oct-2008::08:15:30 === module: stats elapsed: 4.994361 time_to_client: 5.236234569474154 time_to_server: 15.505128105674318 bytes: 8907 packets: 358 {bytes,per_sec}: 1783 {packets,per_sec}: 71 50 games finished =INFO REPORT==== 6-Oct-2008::08:15:35 === module: stats elapsed: 4.923643 time_to_client: 7.458330178363772 time_to_server: 49.56836180504743 bytes: 14380 packets: 581 {bytes,per_sec}: 2920 {packets,per_sec}: 118 100 games finished 150 games finished =INFO REPORT==== 6-Oct-2008::08:15:40 === module: stats elapsed: 5.014354 time_to_client: 10.303327121777983 time_to_server: 64.27703119134696 bytes: 23849 packets: 960 {bytes,per_sec}: 4756 {packets,per_sec}: 191 200 games finished 250 games finished 300 games finished =INFO REPORT==== 6-Oct-2008::08:15:45 === module: stats elapsed: 4.973468 time_to_client: 13.492860654918857 time_to_server: 106.97844814674687 bytes: 28758 packets: 1162 {bytes,per_sec}: 5782 {packets,per_sec}: 233 350 games finished 400 games finished 450 games finished =INFO REPORT==== 6-Oct-2008::08:15:50 === module: stats elapsed: 4.965927 time_to_client: 20.687073726427755 time_to_server: 46.96422948544525 bytes: 76007 packets: 3071 {bytes,per_sec}: 15305 {packets,per_sec}: 618 500 games finished dmb: exited successfully, 58.529502 seconds elapsed ok (1< at >mothership)5> =INFO REPORT==== 6-Oct-2008::08:15:55 === module: stats elapsed: 4.996499 time_to_client: 1.8395921187621034 time_to_server: 3.3051747276788346 bytes: 3845004 packets: 161772 {bytes,per_sec}: 769539 {packets,per_sec}: 32377 Here are the baffling results from testing on a cluster of 3 separate VMs. Note that the time to client is consistently higher and reaches 3.5 seconds at the end, when the game VM is forced to crash upon a player timeout. --- Distributed --- (1< at >mothership)2> dmb:test(500) gateway:start('1< at >mothership', 4000, 500000) Waiting for game servers... Starting a port server on 4000... Simulating gameplay with 500 games... 50 games started, 262 players 100 games started, 504 players 150 games started, 743 players 200 games started, 1019 players 250 games started, 1288 players 300 games started, 1529 players 350 games started, 1766 players 400 games started, 2057 players 450 games started, 2304 players 500 games started, 2562 players dmb: 500 games launching simultaneously dmb: waiting for games to end... =INFO REPORT==== 6-Oct-2008::08:17:12 === module: stats elapsed: 5.000164 time_to_client: 0.7472338659989799 time_to_server: 0.2868026026862225 bytes: 97276 packets: 5438 {bytes,per_sec}: 19454 {packets,per_sec}: 1087 =INFO REPORT==== 6-Oct-2008::08:17:17 === module: stats elapsed: 4.999986 time_to_client: 0.9655462464556185 time_to_server: 0.30163815339577854 bytes: 49090 packets: 2748 {bytes,per_sec}: 9818 {packets,per_sec}: 549 =INFO REPORT==== 6-Oct-2008::08:17:22 === module: stats elapsed: 4.999992 =INFO REPORT==== 6-Oct-2008::08:17:27 === module: stats elapsed: 5.000022 time_to_client: 903.3217931168908 time_to_server: 8.179055363354317 bytes: 346499 packets: 14736 {bytes,per_sec}: 69299 {packets,per_sec}: 2947 =INFO REPORT==== 6-Oct-2008::08:17:32 === module: stats elapsed: 4.999981 time_to_client: 301.7944063249315 time_to_server: 0.13660450764194335 bytes: 254019 packets: 10412 {bytes,per_sec}: 50803 {packets,per_sec}: 2082 =INFO REPORT==== 6-Oct-2008::08:17:37 === module: stats elapsed: 5.000355 time_to_client: 185.66359294523173 time_to_server: 2.651532941434563 bytes: 63537 packets: 2565 {bytes,per_sec}: 12706 {packets,per_sec}: 512 =INFO REPORT==== 6-Oct-2008::08:17:42 === module: stats elapsed: 4.999885 time_to_client: 1501.014993336486 time_to_server: 35.811546393119464 bytes: 405683 packets: 16375 {bytes,per_sec}: 81138 {packets,per_sec}: 3275 vvvvv the game serving VM crash dumps here, as requested ** exception error: no case clause matching noconnection in function dmb:wait_for_games/1 (1< at >mothership)3> =INFO REPORT==== 6-Oct-2008::08:17:47 === module: stats elapsed: 4.999809 time_to_client: 3496.1493304273376 time_to_server: 0.09871293629933679 bytes: 286105 packets: 11573 {bytes,per_sec}: 57223 {packets,per_sec}: 2314 -- wagerlabs.com Joel Reymont 2008-10-06T07:53:52 http://comments.gmane.org/gmane.comp.lang.erlang.general/33553 Hi There, The Erlang Course: * http://www.erlang.org/course/course.html ...doesn't have any obvious attribution as to who or what legal entity owns the copyright and other rights to it. Does anyone know who the IP owner actually is and if there are any specific restrictions on its use (eg. not in a commercial setting)? DSL David Lloyd 2008-10-06T05:31:23 http://comments.gmane.org/gmane.comp.lang.erlang.general/33552 term_to_binary() outputs a binary. what is the format of that binary? I would like to create a "unpacker/packer" for that format in ActionScript3, and avoid the use of XML (which Im using now for Flash-to-Erlang) communication altogether. it would be faster, less code, and much more efficient from the bandwidth point of view. is there a document someplace that gives the byte layout maybe? thank you deepblue_other 2008-10-06T01:13:59 http://comments.gmane.org/gmane.comp.lang.erlang.general/33546 hello everyone Im building a system with a Flash front-end and an Erlang back-end and have some confusion in a case where there is a single socket on the back-end per user (per single socket on the front-end). I want to have multiple independent objects on the front-end send messages to the back-end, but am not sure how the simultaneous transmission would be handled. This probably stems from my somewhat clowdly understanding of TCP. Say there are 3 objects that initiate a send() method on the front-end (almost at the same time) and send a semi large message each to the back-end. Each message would be ID'd by the front-end so that when received back it can be routed to the appropriate callback. Is this possible? since the packets are being assembled in the {tcp, Socket, Data} pattern match, peace by peace, would the correct peaces of the individual messages be stiched together? (doesnt seem like they would). if that wont work then I would just have the serialize the sending/receiving, which is not too horrible... thanks deepblue_other 2008-10-05T16:07:08 http://comments.gmane.org/gmane.comp.lang.erlang.general/33542 Dear Erlang Folks in Berlin and thereabouts, This month's Erlang User Group[1] meeting will sport an "Introduction to Erlang" by Florian Ebeling. Florian stepped up to satisfy frequent request by newcomers to give a introductory presentation about Erlang. Thanks Florian! This event is open to everyone, not just members of the Erlang User. Please give us a shout on the Google Group [1] if you are planning to come. We meet at Z-Bar[2], Bergstr.2, Berlin Mitte[3], 20:00 on October 8th, 2008, listen to Florian's presentation and then have a few beers. Please spread the word, thank you! Cheers, Jan -- [1] http://groups.google.com/group/erlang-berlin [2] http://z-bar.de/ [3] http://maps.google.com/maps?f=q&hl=en&geocode=&q=z-bar&sll=52.491349,13.427872&sspn=0.006637,0.013733&ie=UTF8&ll=52.531887,13.401947&spn=0.053048,0.109863&z=13 Jan Lehnardt 2008-10-05T11:02:20 http://comments.gmane.org/gmane.comp.lang.erlang.general/33536 hello everyone Im building a system with a Flash front-end and an Erlang back-end and have some confusion in a case where there is a single socket on the back-end per user (per single socket on the front-end). I want to have multiple independent objects on the front-end send messages to the back-end, but am not sure how the simultaneous transmission would be handled. This probably stems from my somewhat clowdly understanding of TCP. Say there are 3 objects that initiate a send() method on the front-end (almost at the same time) and send a semi large message each to the back-end. Each message would be ID'd by the front-end so that when received back it can be routed to the appropriate callback. Is this possible? since the packets are being assembled in the {tcp, Socket, Data} pattern match, peace by peace, would the correct peaces of the individual messages be stiched together? (doesnt seem like they would). if that wont work then I would just have the serialize the sending/receiving, which is not too horrible... thanks deepblue_other 2008-10-05T03:16:23 http://comments.gmane.org/gmane.comp.lang.erlang.general/33535 hello I have this going on FunVar = fun() -> ... FunVar() end. so the compiler is complaining that FunVar is unbound at the place where its being used inside fun(); this makes sense, however Im wondering how to make this into a recursive function since there's no name to reference the function with. thanks deepblue_other 2008-10-05T03:19:04 http://comments.gmane.org/gmane.comp.lang.erlang.general/33526 Greg Burri 2008-10-04T16:19:53 http://comments.gmane.org/gmane.comp.lang.erlang.general/33516 denis 2008-10-03T21:40:43 http://comments.gmane.org/gmane.comp.lang.erlang.general/33514 Edwin Fine 2008-10-03T19:02:15 http://comments.gmane.org/gmane.comp.lang.erlang.general/33513 Sean Payne 2008-10-03T18:52:09 http://comments.gmane.org/gmane.comp.lang.erlang.general/33511 Will 2008-10-03T17:20:00 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.comp.lang.erlang.general