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• XNA - Keyboard text input

  - by Sekhat

  Okay, so basically I want to be able to retrieve keyboard text. Like entering text into a text field or something. I'm only writing my game for windows. I've disregarded using Guide.BeginShowKeyboardInput because it breaks the feel of a self contained game, and the fact that the Guide always shows XBOX buttons doesn't seem right to me either. Yes it's the easiest way, but I don't like it. Next I tried using System.Windows.Forms.NativeWindow. I created a class that inherited from it, and passed it the Games window handle, implemented the WndProc function to catch WM_CHAR (or WM_KEYDOWN) though the WndProc got called for other messages, WM_CHAR and WM_KEYDOWN never did. So I had to abandon that idea, and besides, I was also referencing the whole of Windows forms, which meant unnecessary memory footprint bloat. So my last idea was to create a Thread level, low level keyboard hook. This has been the most successful so far. I get WM_KEYDOWN message, (not tried WM_CHAR yet) translate the virtual keycode with Win32 funcation MapVirtualKey to a char. And I get my text! (I'm just printing with Debug.Write at the moment) A couple problems though. It's as if I have caps lock on, and an unresponsive shift key. (Of course it's not however, it's just that there is only one Virtual Key Code per key, so translating it only has one output) and it adds overhead as it attaches itself to the Windows Hook List and isn't as fast as I'd like it to be, but the slowness could be more due to Debug.Write. Has anyone else approached this and solved it, without having to resort to an on screen keyboard? or does anyone have further ideas for me to try? thanks in advance. note: This is cross posted from the XNA Creators Forums, so if I get an answer there I'll post it here and Vice-Versa Question asked by Jimmy Maybe I'm not understanding the question, but why can't you use the XNA Keyboard and KeyboardState classes? My comment: It's because though you can read keystates, you can't get access to typed text as and how it is typed by the user. So let me further clarify. I want to implement being able to read text input from the user as if they are typing into textbox is windows. The keyboard and KeyboardState class get states of all keys, but I'd have to map each key and combination to it's character representation. This falls over when the user doesn't use the same keyboard language as I do especially with symbols (my double quotes is shift + 2, while american keyboards have theirs somewhere near the return key).

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• XmlReader throws on an RSS feed, when the RSS document includes an embedded <script> block.

  - by Cheeso

  The code: using (XmlReader xmlr = XmlReader.Create(new StringReader(allXml))) { var items = from item in SyndicationFeed.Load(xmlr).Items select item; } The exception: Exception: System.Xml.XmlException: Unexpected node type Element. ReadElementString method can only be called on elements with simple or empty content. Line 11, position 25. at System.Xml.XmlReader.ReadElementString() at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadXml(XmlReader reader, SyndicationFeed result) at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadFeed(XmlReader reader) at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadFrom(XmlReader reader) at System.ServiceModel.Syndication.SyndicationFeed.Load[TSyndicationFeed](XmlReader reader) at System.ServiceModel.Syndication.SyndicationFeed.Load(XmlReader reader) at Ionic.ToolsAndTests.ReadRss.Run() in c:\dev\dotnet\ReadRss.cs:line 90 The XML content: <?xml version="1.0" encoding="utf-8"?> <?xml-stylesheet type="text/xsl" href="https://www.ibm.com/developerworks/mydeveloperworks/blogs/roller-ui/styles/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" > <channel> <title>Software architecture, software engineering, and Renaissance Jazz</title> <link>https://www.ibm.com/developerworks/mydeveloperworks/blogs/gradybooch</link> <atom:link rel="self" type="application/rss+xml" href="https://www.ibm.com/developerworks/mydeveloperworks/blogs/gradybooch/feed/entries/rss?lang=en" /> <description>Software architecture, software engineering, and Renaissance Jazz</description> <language>en-us</language> <copyright>Copyright <script type='text/javascript'> document.write(blogsDate.date.localize (1273534889181));</script></copyright> <lastBuildDate>Mon, 10 May 2010 19:41:29 -0400</lastBuildDate> As you can see, on line 11, at position 25, there's a script block inside the <copyright> element. Other people have reported similar errors with other XML documents. The way I worked around this was to do a StreamReader.ReadToEnd, then do Regex.Replace on the result of that to yank out the script block, before passing the modified string to XmlReader.Create(). Feels like a hack. Has anyone got a better approach? I don't like this because I have to read in a 125k string into memory. Is it valid rss to include "complex content" like that - a script block inside an element? Thanks.

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• C++ How to deep copy a struct with unknown datatype?

  - by Ewald Peters

  hi, i have a "data provider" which stores its output in a struct of a certain type, for instance struct DATA_TYPE1{ std::string data_string; }; then this struct has to be casted into a general datatype, i thought about void * or char *, because the "intermediate" object that copies and stores it in its binary tree should be able to store many different types of such struct data. struct BINARY_TREE_ENTRY{ void * DATA; struct BINARY_TREE_ENTRY * next; }; this void * is then later taken by another object that casts the void * back into the (struct DATA_TYPE1 *) to get the original data. so the sender and the receiver know about the datatype DATA_TYPE1 but not the copying object inbetween. but how can the intermidiate object deep copy the contents of the different structs, when it doesn't know the datatype, only void * and it has no method to copy the real contents; dynamic_cast doesn't work for void *; the "intermediate" object should do something like: void store_data(void * CASTED_DATA_STRUCT){ void * DATA_COPY = create_a_deepcopy_of(CASTED_DATA_STRUCT); push_into_bintree(DATA_COPY); } a simple solution would be that the sending object doesn't delete the sent data struct, til the receiving object got it, but the sending objects are dynamically created and deleted, before the receiver got the data from the intermediate object, for asynchronous communication, therefore i want to copy it. instead of converting it to void * i also tried converting to a superclass pointer of which the intermediate copying object knows about, and which is inherited by all the different datatypes of the structs: struct DATA_BASE_OBJECT{ public: DATA_BASE_OBJECT(){} DATA_BASE_OBJECT(DATA_BASE_OBJECT * old_ptr){ std::cout << "this should be automatically overridden!" << std::endl; } virtual ~DATA_BASE_OBJECT(){} }; struct DATA_TYPE1 : public DATA_BASE_OBJECT { public: string str; DATA_TYPE1(){} ~DATA_TYPE1(){} DATA_TYPE1(DATA_TYPE1 * old_ptr){ str = old_ptr->str; } }; and the corresponding binary tree entry would then be: struct BINARY_TREE_ENTRY{ struct DATA_BASE_OBJECT * DATA; struct BINARY_TREE_ENTRY * next; }; and to then copy the unknown datatype, i tried in the class that just gets the unknown datatype as a struct DATA_BASE_OBJECT * (before it was the void *): void * copy_data(DATA_BASE_OBJECT * data_that_i_get_in_the_sub_struct){ struct DATA_BASE_OBJECT * copy_sub = new DATA_BASE_OBJECT(data_that_i_get_in_the_sub_struct); push_into_bintree(copy_sub); } i then added a copy constructor to the DATA_BASE_OBJECT, but if the struct DATA_TYPE1 is first casted to a DATA_BASE_OBJECT and then copied, the included sub object DATA_TYPE1 is not also copied. i then thought what about finding out the size of the actual object to copy and then just memcopy it, but the bytes are not stored in one row and how do i find out the real size in memory of the struct DATA_TYPE1 which holds a std::string? Which other c++ methods are available to deepcopy an unknown datatype (and to maybe get the datatype information somehow else during runtime) thanks Ewald

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• Nginx + php-fpm "504 Gateway Time-out" error with almost zero load (on a test-server)

  - by rahul286

  After debugging for 6-hours - I am giving this up :| We have a nginx+php-fpm+mysql in LAN with almost 100 wordpress (created and used by different designers/developers all working on test wordpres setup) We are using nginx without any issues from long. Today, all of a sudden - nginx started returning "504 Gateway Time-out" out of the blue... I checked nginx error log for a virtual host... 2010/09/06 21:24:24 [error] 12909#0: *349 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *349 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *443 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:12 [error] 12909#0: *443 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:08:32 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:33 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:44 [error] 12909#0: *1313 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:53 [error] 12909#0: *1313 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" As I run php-fpm on port 9000 via TCP mode, I ran "netstat | grep 9000" and noticed something unusual... (Pasting partial output here for ease of read) tcp 9 0 localhost:9000 localhost:36094 CLOSE_WAIT 14269/php5-fpm tcp 0 0 localhost:46664 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36135 CLOSE_WAIT - tcp 1257 0 localhost:9000 localhost:36125 CLOSE_WAIT - tcp 9 0 localhost:9000 localhost:36102 CLOSE_WAIT 14268/php5-fpm tcp 0 0 localhost:46662 localhost:9000 FIN_WAIT2 - tcp 745 0 localhost:9000 localhost:46644 CLOSE_WAIT - tcp 0 0 localhost:46658 localhost:9000 FIN_WAIT2 - tcp 1265 0 localhost:9000 localhost:46607 CLOSE_WAIT - tcp 0 0 localhost:46672 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1257 0 localhost:9000 localhost:36119 CLOSE_WAIT - tcp 1265 0 localhost:9000 localhost:46613 CLOSE_WAIT - tcp 0 0 localhost:46646 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36137 CLOSE_WAIT - tcp 0 0 localhost:46670 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1265 0 localhost:9000 localhost:46619 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46668 ESTABLISHED - tcp 0 0 localhost:46648 localhost:9000 FIN_WAIT2 - tcp 1336 0 localhost:9000 localhost:46670 ESTABLISHED - tcp 9 0 localhost:9000 localhost:36108 CLOSE_WAIT 14274/php5-fpm tcp 1336 0 localhost:9000 localhost:46684 ESTABLISHED - tcp 0 0 localhost:46674 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1336 0 localhost:9000 localhost:46666 ESTABLISHED - tcp 1257 0 localhost:9000 localhost:46648 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46678 ESTABLISHED - tcp 0 0 localhost:46668 localhost:9000 ESTABLISHED 12909/nginx: wo There are plenty of "CLOSE_WAIT" & "FIN_WAIT2" pairs as highlighted below (in above output): tcp 1337 0 localhost:9000 localhost:46680 CLOSE_WAIT - tcp 0 0 localhost:46680 localhost:9000 FIN_WAIT2 - Please note port 46680 in above. I enabled mysql slow queries error log, but it didn't work. As of now restarting php5-fpm every minute via a cronjob (see command below) keeping everything running "smoothly" but I hate patchwork and want to solve this... 1 * * * * service php5-fpm restart > /dev/null I searched extensively on Google - got no help. As mentioned, this a test-server in LAN, CPU load is never crossed 0.10 and memory usage is also below 25% (System has 2GB RAM and ubuntu-server installed) So if you find its time-confusing to help me out, please atleast drop a hint. Thanks in advance for help. -Rahul (note - this is reposting of - http://forum.nginx.org/read.php?11,127694) Update: I found answer, which is posted below.

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• Seeking for faster $.(':data(key)')

  - by PoltoS

  I'm writing an extension to jQuery that adds data to DOM elements using el.data('lalala', my_data); and then uses that data to upload elements dynamically. Each time I get new data from the server I need to update all elements having el.data('lalala') != null; To get all needed elements I use an extension by James Padolsey: $(':data(lalala)').each(...); Everything was great until I came to the situation where I need to run that code 50 times - it is very slow! It takes about 8 seconds to execute on my page with 3640 DOM elements var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery(':data(lalala)').each(function() { x++; }); }; console.log(((new Date).getTime()-t)/1000); Since I don't need RegExp as parameter of :data selector I've tried to replace this by var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery('*').each(function() { if ($(this).data('lalala')) x++; }); }; console.log(((new Date).getTime()-t)/1000); This code is faster (5 sec), but I want get more. Q Are there any faster way to get all elements with this data key? In fact, I can keep an array with all elements I need, since I execute .data('key') in my module. Checking 100 elements having the desired .data('lalala') is better then checking 3640 :) So the solution would be like for (i in elements) { el = elements[i]; .... But sometimes elements are removed from the page (using jQuery .remove()). Both solutions described above [$(':data(lalala)') solution and if ($(this).data('lalala'))] will skip removed items (as I need), while the solution with array will still point to removed element (in fact, the element would not be really deleted - it will only be deleted from the DOM tree - because my array will still have a reference). I found that .remove() also removes data from the node, so my solution will change into var toRemove = []; for (vari in elements) { var el = elements[i]; if ($(el).data('lalala')) .... else toRemove.push(i); }; for (var ii in toRemove) elements.splice(toRemove[ii], 1); // remove element from array This solution is 100 times faster! Q Will the garbage collector release memory taken by DOM elements when deleted from that array? Remember, elements have been referenced by DOM tree, we made a new reference in our array, then removed with .remove() and then removed from the array. Is there a better way to do this?

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• Load-balancing between a Procurve switch and a server

  - by vlad

  Hello I've been searching around the web for this problem i've been having. It's similar in a way to this question: How exactly & specifically does layer 3 LACP destination address hashing work? My setup is as follows: I have a central switch, a Procurve 2510G-24, image version Y.11.16. It's the center of a star topology, there are four switches connected to it via a single gigabit link. Those switches service the users. On the central switch, I have a server with two gigabit interfaces that I want to bond together in order to achieve higher throughput, and two other servers that have single gigabit connections to the switch. The topology looks as follows: sw1 sw2 sw3 sw4 | | | | --------------------- | sw0 | --------------------- || | | srv1 srv2 srv3 The servers were running FreeBSD 8.1. On srv1 I set up a lagg interface using the lacp protocol, and on the switch I set up a trunk for the two ports using lacp as well. The switch showed that the server was a lacp partner, I could ping the server from another computer, and the server could ping other computers. If I unplugged one of the cables, the connection would keep working, so everything looked fine. Until I tested throughput. There was only one link used between srv1 and sw0. All testing was conducted with iperf, and load distribution was checked with systat -ifstat. I was looking to test the load balancing for both receive and send operations, as I want this server to be a file server. There were therefore two scenarios: iperf -s on srv1 and iperf -c on the other servers iperf -s on the other servers and iperf -c on srv1 connected to all the other servers. Every time only one link was used. If one cable was unplugged, the connections would keep going. However, once the cable was plugged back in, the load was not distributed. Each and every server is able to fill the gigabit link. In one-to-one test scenarios, iperf was reporting around 940Mbps. The CPU usage was around 20%, which means that the servers could withstand a doubling of the throughput. srv1 is a dell poweredge sc1425 with onboard intel 82541GI nics (em driver on freebsd). After troubleshooting a previous problem with vlan tagging on top of a lagg interface, it turned out that the em could not support this. So I figured that maybe something else is wrong with the em drivers and / or lagg stack, so I started up backtrack 4r2 on this same server. So srv1 now uses linux kernel 2.6.35.8. I set up a bonding interface bond0. The kernel module was loaded with option mode=4 in order to get lacp. The switch was happy with the link, I could ping to and from the server. I could even put vlans on top of the bonding interface. However, only half the problem was solved: if I used srv1 as a client to the other servers, iperf was reporting around 940Mbps for each connection, and bwm-ng showed, of course, a nice distribution of the load between the two nics; if I run the iperf server on srv1 and tried to connect with the other servers, there was no load balancing. I thought that maybe I was out of luck and the hashes for the two mac addresses of the clients were the same, so I brought in two new servers and tested with the four of them at the same time, and still nothing changed. I tried disabling and reenabling one of the links, and all that happened was the traffic switched from one link to the other and back to the first again. I also tried setting the trunk to "plain trunk mode" on the switch, and experimented with other bonding modes (roundrobin, xor, alb, tlb) but I never saw any traffic distribution. One interesting thing, though: one of the four switches is a Cisco 2950, image version 12.1(22)EA7. It has 48 10/100 ports and 2 gigabit uplinks. I have a server (call it srv4) with a 4 channel trunk connected to it (4x100), FreeBSD 8.0 release. The switch is connected to sw0 via gigabit. If I set up an iperf server on one of the servers connected to sw0 and a client on srv4, ALL 4 links are used, and iperf reports around 330Mbps. systat -ifstat shows all four interfaces are used. The cisco port-channel uses src-mac to balance the load. The HP should use both the source and destination according to the manual, so it should work as well. Could this mean there is some bug in the HP firmware? Am I doing something wrong?

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• Which OAuth library do you find works best for Objective-C/iPhone?

  - by Brennan

  I have been looking to switch to OAuth for my Twitter integration code and now that there is a deadline in less than 7 weeks (see countdown link) it is even more important to make the jump to OAuth. I have been doing Basic Authentication which is extremely easy. Unfortunately OAuth does not appear to be something that I would whip together in a couple of hours. http://www.countdowntooauth.com/ So I am looking to use a library. I have put together the following list. MPOAuth MGTwitterEngine OAuthConsumer I see that MPOAuth has some great features with a good deal of testing code in place but there is one big problem. It does not work. The sample iPhone project that is supposed to authenticate with Twitter causes an error which others have identified and logged as a bug. http://code.google.com/p/mpoauthconnection/issues/detail?id=29 The last code change was March 11 and this bug was filed on March 30. It has been over a month and this critical bug has not been fixed yet. So I have moved on to MGTwitterEngine. I pulled down the source code and loaded it up in Xcode. Immediately I find that there are a few dependencies and the README file does not have a clear list of steps to fetch those dependencies and integrate them with the project so that it builds successfully. I see this as a sign that the project is not mature enough for prime time. I see also that the project references 2 libraries for JSON when one should be enough. One is TouchJSON which has worked well for me so I am again discouraged from relying on this project for my applications. I did find that MGTwitterEngine makes use of OAuthConsumer which is one of many OAuth projects hosted by an OAuth project on Google Code. http://code.google.com/p/oauth/ http://code.google.com/p/oauthconsumer/wiki/UsingOAuthConsumer It looks like OAuthConsumer is a good choice at first glance. It is hosted with other OAuth libraries and has some nice documentation with it. I pulled down the code and it builds without errors but it does have many warnings. And when I run the new Build and Analyze feature in Xcode 3.2 I see 50 analyzer results. Many are marked as potential memory leaks which would likely lead to instability in any app which uses this library. It seems there is no clear winner and I have to go with something before the big Twitter OAuth deadline. Any suggestions?

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• ASP.Net Web Farm Monitoring

  - by cisellis

  I am looking for suggestions on doing some simple monitoring of an ASP.Net web farm as close to real-time as possible. The objectives of this question are to: Identify the best way to monitor several Windows Server production boxes during short (minutes long) period of ridiculous load Receive near-real-time feedback on a few key metrics about each box. These are simple metrics available via WMI such as CPU, Memory and Disk Paging. I am defining my time constraints as soon as possible with 120 seconds delayed being the absolute upper limit. Monitor whether any given box is up (with "up" being defined as responding web requests in a reasonable amount of time) Here are more details, things I've tried, etc. I am not interested in logging. We have logging solutions in place. I have looked at solutions such as ELMAH which don't provide much in the way of hardware monitoring and are not visible across an entire web farm. ASP.Net Health Monitoring is too broad, focuses too much on logging and is not acceptable for deep analysis. We are on Amazon Web Services and we have looked into CloudWatch. It looks great but messages in the forum indicate that the metrics are often a few minutes behind, with one thread citing 2 minutes as the absolute soonest you could expect to receive the feedback. This would be good to have for later analysis but does not help us real-time Stuff like JetBrains profiler is good for testing but again, not helpful during real-time monitoring. The closest out-of-box solution I've seen is Nagios which is free and appears to measure key indicators on any kind of box, including Windows. However, it appears to require a Linux box to run itself on and a good deal of manual configuration. I'd prefer to not spend my time mining config files and then be up a creek when it fails in production since Linux is not my main (or even secondary) environment. Are there any out-of-box solutions that I am missing? Obviously a windows-based solution that is easy to setup is ideal. I don't require many bells and whistles. In the absence of an out-of-box solution, it seems easy for me to write something simple to handle what I need. I've been thinking a simple client-server setup where the server requests a few WMI metrics from each client over http and sticks them in a database. We could then monitor the metrics via a query or a dashboard or something. If the client doesn't respond, it's effectively down. Any problems with this, best practices, or other ideas? Thanks for any help/feedback.

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• Using FFmpeg in .net?

  - by daniel

  So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management than if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Converting AES encryption token code in C# to php

  - by joey

  Hello, I have the following .Net code which takes two inputs. 1) A 128 bit base 64 encoded key and 2) the userid. It outputs the AES encrypted token. I need the php equivalent of the same code, but dont know which corresponding php classes are to be used for RNGCryptoServiceProvider,RijndaelManaged,ICryptoTransform,MemoryStream and CryptoStream. Im stuck so any help regarding this would be really appreciated. using System; using System.Text; using System.IO; using System.Security.Cryptography; class AESToken { [STAThread] static int Main(string[] args) { if (args.Length != 2) { Console.WriteLine("Usage: AESToken key userId\n"); Console.WriteLine("key Specifies 128-bit AES key base64 encoded supplied by MediaNet to the partner"); Console.WriteLine("userId specifies the unique id"); return -1; } string key = args[0]; string userId = args[1]; StringBuilder sb = new StringBuilder(); // This example code uses the magic string “CAMB2B”. The implementer // must use the appropriate magic string for the web services API. sb.Append("CAMB2B"); sb.Append(args[1]); // userId sb.Append('|'); // pipe char sb.Append(System.DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ssUTC")); //timestamp Byte[] payload = Encoding.ASCII.GetBytes(sb.ToString()); byte[] salt = new Byte[16]; // 16 bytes of random salt RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(salt); // the plaintext is 16 bytes of salt followed by the payload. byte[] plaintext = new byte[salt.Length + payload.Length]; salt.CopyTo(plaintext, 0); payload.CopyTo(plaintext, salt.Length); // the AES cryptor: 128-bit key, 128-bit block size, CBC mode RijndaelManaged cryptor = new RijndaelManaged(); cryptor.KeySize = 128; cryptor.BlockSize = 128; cryptor.Mode = CipherMode.CBC; cryptor.GenerateIV(); cryptor.Key = Convert.FromBase64String(args[0]); // the key byte[] iv = cryptor.IV; // the IV. // do the encryption ICryptoTransform encryptor = cryptor.CreateEncryptor(cryptor.Key, iv); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write); cs.Write(plaintext, 0, plaintext.Length); cs.FlushFinalBlock(); byte[] ciphertext = ms.ToArray(); ms.Close(); cs.Close(); // build the token byte[] tokenBytes = new byte[iv.Length + ciphertext.Length]; iv.CopyTo(tokenBytes, 0); ciphertext.CopyTo(tokenBytes, iv.Length); string token = Convert.ToBase64String(tokenBytes); Console.WriteLine(token); return 0; } } Please help. Thank You.

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• Manipulating matrix operations (transpose, negation, addition, and mutiplication) using functions in

  - by user292489

  I was trying to manipulate matrices in my input file using functions. My input file is: A 3 3 1 2 3 4 5 6 7 8 9 B 3 3 1 0 0 0 1 0 0 0 1 C 2 3 3 5 8 -1 -2 -3 D 3 5 0 0 0 1 0 1 0 1 0 1 0 1 0 0 1 E 1 1 10 F 3 10 1 0 2 0 3 0 4 0 5 0 0 2 3 -1 -3 -4 -3 8 3 7 0 0 0 4 6 5 8 2 -1 10 I am having trouble in implementing the functions that I declared. I assumed my program will perform those operations: transpose, negate, add, and multiply matices according to the users choice: /* once this program is compiled and executed, it will perform the basic matrix * operations: negation, transpose, addition, and multiplication. */ #include <stdio.h> #include <stdlib.h> #define MAX 10 int readmatrix(FILE *input, char martixname[6],int , mat[10][10], int i, int j); void printmatrix(char matrixname[6], int mat[10][10], int i, int j); void Negate(char matrixname[6], int mat[10][10], int i, int j); void add(char matrixname[6], int mat[10][10],int i, int k); void multiply(char matrixname[], int mat[][10], char A[], int i, int k); void transpose (char matrixname[], int mat[][10], char A[], int); void printT(int mat[][10], int); int selctoption(); char selectmatrix(); int main(int argc, char *argv[]) { char matrixtype[6]; int mat[][10]; FILE *filein; int size; int optionop; int matrixop; int option; if (argc != 2) { printf("Usage: executable input.\n"); exit(0); } filein = fopen(argv[1], "r"); if (!filein) { printf("ERROR: input file not found.\n"); exit (0); } size = readmatrix (filein, matrixtype); printmatrix(matrix[][10], size); option = selectoption(); matrixtype = selectmatrix(); //printf("You have: %5.2f ", deposit); optionop = readmatrix(option, matrix[][10], size); if (choiceop == 6) { printf("Thanks for using the matrix operation program.\n"); exit(0); } printf("Please select from the following matrix operations:\n") printf("\t1. Print matrix\n"); printf("\t2. Negate matrix\n"); printf("\t3. Transpose matrix\n"); printf("\t4. Add matrices\n"); printf("\t5. Multiply matrices\n"); printf("\t6. Quit\n"); fclose(filein); return 0; } do { printf("Please select option(1-%d):", optionop); scanf("%d", &matrixop); } while(matrixop <= 0 || matrixop > optionop); void readmatrix (FILE *in, int mat[][10], char A[], int i, int j) { int i=0,j = 0; while (fscanf(in, "%d", &mat[i][j]) != EOF) return 0; } // I would appreciate anyone's feedback.

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• Simple Convention Automapper for two-way Mapping (Entities to/from ViewModels)

  - by Omu

  UPDATE: this stuff has evolved into a nice project, see it at http://valueinjecter.codeplex.com check this out, I just wrote a simple automapper, it takes the value from the property with the same name and type of one object and puts it into another, and you can add exceptions (ifs, switch) for each type you may need so tell me what do you think about it ? I did it so I could do something like this: Product –> ProductDTO ProductDTO –> Product that's how it begun: I use the "object" type in my Inputs/Dto/ViewModels for DropDowns because I send to the html a IEnumerable<SelectListItem> and I receive a string array of selected keys back public void Map(object a, object b) { var pp = a.GetType().GetProperties(); foreach (var pa in pp) { var value = pa.GetValue(a, null); // property with the same name in b var pb = b.GetType().GetProperty(pa.Name); if (pb == null) { //no such property in b continue; } if (pa.PropertyType == pb.PropertyType) { pb.SetValue(b, value, null); } } } UPDATE: the real usage: the Build methods (Input = Dto): public static TI BuildInput<TI, T>(this T entity) where TI: class, new() { var input = new TI(); input = Map(entity, input) as TI; return input; } public static T BuildEntity<T, TI, TR>(this TI input) where T : class, new() where TR : IBaseAdvanceService<T> { var id = (long)input.GetType().GetProperty("Id").GetValue(input, null); var entity = LocatorConfigurator.Resolve<TR>().Get(id) ?? new T(); entity = Map(input, entity) as T; return entity; } public static TI RebuildInput<T, TI, TR>(this TI input) where T: class, new() where TR : IBaseAdvanceService<T> where TI : class, new() { return input.BuildEntity<T, TI, TR>().BuildInput<TI, T>(); } in the controller: public ActionResult Create() { return View(new Organisation().BuildInput<OrganisationInput, Organisation>()); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(OrganisationInput o) { if (!ModelState.IsValid) { return View(o.RebuildInput<Organisation,OrganisationInput, IOrganisationService>()); } organisationService.SaveOrUpdate(o.BuildEntity<Organisation, OrganisationInput, IOrganisationService>()); return RedirectToAction("Index"); } The real Map method public static object Map(object a, object b) { var lookups = GetLookups(); var propertyInfos = a.GetType().GetProperties(); foreach (var pa in propertyInfos) { var value = pa.GetValue(a, null); // property with the same name in b var pb = b.GetType().GetProperty(pa.Name); if (pb == null) { continue; } if (pa.PropertyType == pb.PropertyType) { pb.SetValue(b, value, null); } else if (lookups.Contains(pa.Name) && pa.PropertyType == typeof(LookupItem)) { pb.SetValue(b, (pa.GetValue(a, null) as LookupItem).GetSelectList(pa.Name), null); } else if (lookups.Contains(pa.Name) && pa.PropertyType == typeof(object)) { pb.SetValue(b, pa.GetValue(a, null).ReadSelectItemValue(), null); } else if (pa.PropertyType == typeof(long) && pb.PropertyType == typeof(Organisation)) { pb.SetValue(b, pa.GetValue<long>(a).ReadOrganisationId(), null); } else if (pa.PropertyType == typeof(Organisation) && pb.PropertyType == typeof(long)) { pb.SetValue(b, pa.GetValue<Organisation>(a).Id, null); } } return b; }

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• Is this question too hard for a seasoned C++ architect?

  - by Monomer

  Background Information We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++. The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence. Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test. After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs) My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question. The Question There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j. class C { public: int foo() {...} int boo() {...} int boo_and_foo() {...} int foo_and_boo() {...} }; In code one might write: C c; . . int i = c.foo() + c.boo(); But it would be better to have: int i = c.foo_and_boo(); What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter. Note that foo and boo are not commutative. Possible Solution We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail. We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more. Is this really a difficult question? Should it be removed? Or are we just not seeing the right candidates?

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• Unable to cast lists with Reflection in C#

  - by DrLazer

  I am having a lot of trouble with Reflection in C# at the moment. The app I am writing allows the user to modify the attributes of certain objects using a config file. I want to be able to save the object model (users project) to XML. The function below is called in the middle of a foreach loop, looping through a list of objects that contain all the other objects in the project within them. The idea is, that it works recursively to translate the object model into XML. Dont worry about the call to "Unreal" that just modifes the name of the objects slightly if they contain certain words. private void ReflectToXML(object anObject, XmlElement parentElement) { Type aType = anObject.GetType(); XmlElement anXmlElement = m_xml.CreateElement(Unreal(aType.Name)); parentElement.AppendChild(anXmlElement); PropertyInfo[] pinfos = aType.GetProperties(); //loop through this objects public attributes foreach (PropertyInfo aInfo in pinfos) { //if the attribute is a list Type propertyType = aInfo.PropertyType; if ((propertyType.IsGenericType)&&(propertyType.GetGenericTypeDefinition() == typeof(List<>))) { List<object> listObjects = (aInfo.GetValue(anObject,null) as List<object>); foreach (object aListObject in listObjects) { ReflectToXML(aListObject, anXmlElement); } } //attribute is not a list else anXmlElement.SetAttribute(aInfo.Name, ""); } } If an object attributes are just strings then it should be writing them out as string attributes in the XML. If an objects attributes are lists, then it should recursively call "ReflectToXML" passing itself in as a parameter, thereby creating the nested structure I require that nicely reflect the object model in memory. The problem I have is with the line List<object> listObjects = (aInfo.GetValue(anObject,null) as List<object>); The cast doesn't work and it just returns null. While debugging I changed the line to object temp = aInfo.GetValue(anObject,null); slapped a breakpoint on it to see what "GetValue" was returning. It returns a "Generic list of objects" Surely I should be able to cast that? The annoying thing is that temp becomes a generic list of objects but because i declared temp as a singular object, I can't loop through it because it has no Enumerator. How can I loop through a list of objects when I only have it as a propertyInfo of a class? I know at this point I will only be saving a list of empty strings out anyway, but thats fine. I would be happy to see the structure save out for now. Thanks in advance

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• Modeling distribution of performance measurements

  - by peterchen

  How would you mathematically model the distribution of repeated real life performance measurements - "Real life" meaning you are not just looping over the code in question, but it is just a short snippet within a large application running in a typical user scenario? My experience shows that you usually have a peak around the average execution time that can be modeled adequately with a Gaussian distribution. In addition, there's a "long tail" containing outliers - often with a multiple of the average time. (The behavior is understandable considering the factors contributing to first execution penalty). My goal is to model aggregate values that reasonably reflect this, and can be calculated from aggregate values (like for the Gaussian, calculate mu and sigma from N, sum of values and sum of squares). In other terms, number of repetitions is unlimited, but memory and calculation requirements should be minimized. A normal Gaussian distribution can't model the long tail appropriately and will have the average biased strongly even by a very small percentage of outliers. I am looking for ideas, especially if this has been attempted/analysed before. I've checked various distributions models, and I think I could work out something, but my statistics is rusty and I might end up with an overblown solution. Oh, a complete shrink-wrapped solution would be fine, too ;) Other aspects / ideas: Sometimes you get "two humps" distributions, which would be acceptable in my scenario with a single mu/sigma covering both, but ideally would be identified separately. Extrapolating this, another approach would be a "floating probability density calculation" that uses only a limited buffer and adjusts automatically to the range (due to the long tail, bins may not be spaced evenly) - haven't found anything, but with some assumptions about the distribution it should be possible in principle. Why (since it was asked) - For a complex process we need to make guarantees such as "only 0.1% of runs exceed a limit of 3 seconds, and the average processing time is 2.8 seconds". The performance of an isolated piece of code can be very different from a normal run-time environment involving varying levels of disk and network access, background services, scheduled events that occur within a day, etc. This can be solved trivially by accumulating all data. However, to accumulate this data in production, the data produced needs to be limited. For analysis of isolated pieces of code, a gaussian deviation plus first run penalty is ok. That doesn't work anymore for the distributions found above. [edit] I've already got very good answers (and finally - maybe - some time to work on this). I'm starting a bounty to look for more input / ideas.

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• Efficiency of Java "Double Brace Initialization"?

  - by Jim Ferrans

  In Hidden Features of Java the top answer mentions Double Brace Initialization, with a very enticing syntax: Set<String> flavors = new HashSet<String>() {{ add("vanilla"); add("strawberry"); add("chocolate"); add("butter pecan"); }}; This idiom creates an anonymous inner class with just an instance initializer in it, which "can use any [...] methods in the containing scope". Main question: Is this as inefficient as it sounds? Should its use be limited to one-off initializations? (And of course showing off!) Second question: The new HashSet must be the "this" used in the instance initializer ... can anyone shed light on the mechanism? Third question: Is this idiom too obscure to use in production code? Summary: Very, very nice answers, thanks everyone. On question (3), people felt the syntax should be clear (though I'd recommend an occasional comment, especially if your code will pass on to developers who may not be familiar with it). On question (1), The generated code should run quickly. The extra .class files do cause jar file clutter, and slow program startup slightly (thanks to coobird for measuring that). Thilo pointed out that garbage collection can be affected, and the memory cost for the extra loaded classes may be a factor in some cases. Question (2) turned out to be most interesting to me. If I understand the answers, what's happening in DBI is that the anonymous inner class extends the class of the object being constructed by the new operator, and hence has a "this" value referencing the instance being constructed. Very neat. Overall, DBI strikes me as something of an intellectual curiousity. Coobird and others point out you can achieve the same effect with Arrays.asList, varargs methods, Google Collections, and the proposed Java 7 Collection literals. Newer JVM languages like Scala, JRuby, and Groovy also offer concise notations for list construction, and interoperate well with Java. Given that DBI clutters up the classpath, slows down class loading a bit, and makes the code a tad more obscure, I'd probably shy away from it. However, I plan to spring this on a friend who's just gotten his SCJP and loves good natured jousts about Java semantics! ;-) Thanks everyone!

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• Java ExecutorService java heap space ptoblems

  - by Sergey Aganezov jr

  I have a little bit of a problem in a multitasking java department. I have a class, called public class ThreadWorker implements Runnable { //some code in here public void run(){ // invokes some recursion method in the ThreadWorker itself, // which will stop eventually { } all in all, pretty simple "worker" that can work on it's on. To work with threads I'm using public static int THREAD_NUMBER = 4; public static ExecutorServide es = Executors.newFixedThreadPool(THREAD_NUMBER); adding instances of ThreadWroker class happens here: public void recursiveMethod(Arraylist<Integers> elements, MyClass data){ if (elements.size() == 0 && data.qualifies()){ ThreadWorker tw = new ThreadWorker(data); es.execute(tw); return; } for (int i=0; i< elements.size(); i++){ // some code to prevent my problem MyClass data1 = new MyClass(data); MyClass data2 = new MyClass(data); ArrayList<Integer> newElements = (ArrayList<Integer>)elements.clone(); data1.update(elements.get(i)); data2.update(-1 * elements.get(i)); newElements.remove(i); recursiveMethod(newElements, data1); recursiveMethod(newElements, data2); { } and the problem is that the depth of the recursion tree is quite big, so as it's width, so a lot of ThreadWorkers are added to the ExecutorService, so after some time on the big input a get Exception in thread "pool-1-thread-2" java.lang.OutOfMemoryError: Java heap space which is caused, as I think because of a ginormous number of ThreadWorkers i'm adding to ExecutorSirvice to be executed, so it runs out of memory. Every ThreadWorker takes about 40 Mb of RAM for all it needs. Is there a method to get how many threads (instances of classes implementing runnable interface) have been added to ExecutorService? So I can add it in the shown above code (int the " // some code to prevent my problem"), as while ("number of threads in the ExecutorService" > 10){ Thread.sleep(10000); } so I won't go to deep or to broad with my recursion and prevent those exception-throwing situations. Sincerely, Sergey Aganezov jr.

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• My block is not retaining some of its objects

  - by Drew Crawford

  From the Blocks documentation: In a reference-counted environment, by default when you reference an Objective-C object within a block, it is retained. This is true even if you simply reference an instance variable of the object. I am trying to implement a completion handler pattern, where a block is given to an object before the work is performed and the block is executed by the receiver after the work is performed. Since I am being a good memory citizen, the block should own the objects it references in the completion handler and then they will be released when the block goes out of scope. I know enough to know that I must copy the block to move it to the heap since the block will survive the stack scope in which it was declared. However, one of my objects is getting deallocated unexpectedly. After some playing around, it appears that certain objects are not retained when the block is copied to the heap, while other objects are. I am not sure what I am doing wrong. Here's the smallest test case I can produce: typedef void (^ActionBlock)(UIView*); In the scope of some method: NSObject *o = [[[NSObject alloc] init] autorelease]; mailViewController = [[[MFMailComposeViewController alloc] init] autorelease]; NSLog(@"o's retain count is %d",[o retainCount]); NSLog(@"mailViewController's retain count is %d",[mailViewController retainCount]); ActionBlock myBlock = ^(UIView *view) { [mailViewController setCcRecipients:[NSArray arrayWithObjects:@"[email protected]",nil]]; [o class]; }; NSLog(@"mailViewController's retain count after the block is %d",[mailViewController retainCount]); NSLog(@"o's retain count after the block is %d",[o retainCount]); Block_copy(myBlock); NSLog(@"o's retain count after the copy is %d",[o retainCount]); NSLog(@"mailViewController's retain count after the copy is %d",[mailViewController retainCount]); I expect both objects to be retained by the block at some point, and I certainly expect their retain counts to be identical. Instead, I get this output: o's retain count is 1 mailViewController's retain count is 1 mailViewController's retain count after the block is 1 o's retain count after the block is 1 o's retain count after the copy is 2 mailViewController's retain count after the copy is 1 o (subclass of NSObject) is getting retained properly and will not go out of scope. However mailViewController is not retained and will be deallocated before the block is run, causing a crash.

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• WPF Choppy Animation

  - by Chris Dunaway

  WPF Windows-XP SP3 I'm having a problem with a simple WPF animation. I use the following Xaml code (in XamlPad and also in a WPF project): <Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" > <Border Name="MyBorder" BorderThickness="10" BorderBrush="Blue" CornerRadius="10" Background="DarkRed" > <Rectangle Name="MyRectangle" Margin="10" StrokeDashArray="2.0,1.0" StrokeThickness="10" RadiusX="10" RadiusY="10" Stroke="Black" StrokeDashOffset="0"> <Rectangle.Triggers> <EventTrigger RoutedEvent="Rectangle.Loaded"> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetName="MyRectangle" Storyboard.TargetProperty="StrokeDashOffset" From="0.0" To="3.0" Duration="0:0:1" RepeatBehavior="Forever" Timeline.DesiredFrameRate="30" /> </Storyboard> </BeginStoryboard> </EventTrigger> </Rectangle.Triggers> </Rectangle> </Border> </Page> It has the effect of causing the border to animate around the rectangle. After a fresh reboot of the machine, this animation is nice and smooth. However, I tend to leave my machine on all the time and after a period time elapses (I don't know how long), the animation starts stuttering and becomes choppy. I thought that it may be memory or resource issues, but after shutting down all other apps and any services that seem unnecessary, the stuttering still continues. However, after a system reboot, the animation is smooth again! I get the same symptoms in a WPF app or in XamlPad. In the case of the app, it doesn't seem to make any difference whether I run in the debugger or if I run the executable directly. I applied the patch at this link: http://support.microsoft.com/kb/981741 and I thought that it had taken care of the issue, but it seems not to have. I have seen some posts that might indicate that using transparency might affect animation, but as you can see, my xaml does not use transparency. Can anyone give me some suggestions on how to determine what the problem is? Are there any WPF diagnostic tools that might help? UPDATE: I have checked my video drivers and they are the latest version. (nVidia GeForce 8400 GS)

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• HP-UX: libstd_v2 in stack trace of JNI code compiled with g++

  - by Miguel Rentes

  Hello, uname -mr: B.11.23 ia64 g++ --version: g++ (GCC) 4.4.0 java -version: Java(TM) SE Runtime Environment (build 1.6.0.06-jinteg_20_jan_2010_05_50-b00) Java HotSpot(TM) Server VM (build 14.3-b01-jre1.6.0.06-rc1, mixed mode) I'm trying to run a Java application that uses JNI. It is crashing inside the JNI code with the following (abbreviated) stack trace: (0) 0xc0000000249353e0 VMError::report_and_die{_ZN7VMError14report_and_dieEv} + 0x440 at /CLO/Components/JAVA_HOTSPOT/Src/src/share/vm/utilities/vmError.cpp:738 [/opt/java6/jre/lib/IA64W/server/libjvm.so] (1) 0xc000000024559240 os::Hpux::JVM_handle_hpux_signal{_ZN2os4Hpux22JVM_handle_hpux_signalEiP9 __siginfoPvi} + 0x760 at /CLO/Components/JAVA_HOTSPOT/Src/src/os_cpu/hp-ux_ia64/vm/os_hp-ux_ia64.cpp:1051 [/opt/java6/jre/lib/IA64W/server/libjvm.so] (2) 0xc0000000245331c0 os::Hpux::signalHandler{_ZN2os4Hpux13signalHandlerEiP9__siginfoPv} + 0x80 at /CLO/Components/JAVA_HOTSPOT/Src/src/os/hp-ux/vm/os_hp-ux.cpp:4295 [/opt/java6/jre/lib/IA64W/server/libjvm.so] (3) 0xe00000010e002620 ---- Signal 11 (SIGSEGV) delivered ---- (4) 0xc0000000000d2d20 __pthread_mutex_lock + 0x400 at /ux/core/libs/threadslibs/src/common/pthreads/mutex.c:3895 [/usr/lib/hpux64/libpthread.so.1] (5) 0xc000000000342e90 __thread_mutex_lock + 0xb0 at ../../../../../core/libs/libc/shared_em_64/../core/threads/wrappers1.c:273 [/usr/lib/hpux64/libc.so.1] (6) 0xc00000000177dff0 _HPMutexWrapper::lock{_ZN15_HPMutexWrapper4lockEPv} + 0x90 [/usr/lib/hpux64/libstd_v2.so.1] (7) 0xc0000000017e9960 std::basic_string,std::allocator{_ZNSsC1ERKSs} + 0x80 [/usr/lib/hpux64/libstd_v2.so.1] (8) 0xc000000008fd9fe0 JniString::str{_ZNK9JniString3strEv} + 0x50 at eg_handler_jni.cxx:50 [/soft/bus-7_0/lib/libbus_registry_jni.so.7.0.0] (9) 0xc000000008fd7060 pt_efacec_se_aut_frk_cmp_registry_REGHandler::getKey{_ZN44pt_efacec_se_aut_frk_cmp_registry_REGHandler6getKeyEP8_jstringi} + 0xa0 [/soft/bus-7_0/lib/libbus_registry_jni.so.7.0.0] (10) 0xc000000008fd17f0 Java_pt_efacec_se_aut_frk_cmp_registry_REGHandler_getKey__Ljava_lang_String_2I + 0xa0 [/soft/bus-7_0/lib/libbus_registry_jni.so.7.0.0] (11) 0x9fffffffdf400ed0 Internal error (-3) while unwinding stack [/CLO/Components/JAVA_HOTSPOT/Src/src/os_cpu/hp-ux_ia64/vm/thread_hp-ux_ia64.cpp:142] This JNI code and dependencies are being compiled using g++, are multithreaded and 64 bit (-pthread -mlp64 -shared -fPIC). The LD_LIBRARY_PATH environment variable is set the dependencies location, and running ldd on the JNI shared libraries finds them all: ldd libbus_registry_jni.so: libefa-d.so.7 = /soft/bus-7_0/lib/libefa-d.so.7 libbus_registry-d.so.7 = /soft/bus-7_0/lib/libbus_registry-d.so.7 libboost_thread-gcc44-mt-d-1_41.so = /usr/local/lib/libboost_thread-gcc44-mt-d-1_41.so libboost_system-gcc44-mt-d-1_41.so = /usr/local/lib/libboost_system-gcc44-mt-d-1_41.so libboost_regex-gcc44-mt-d-1_41.so = /usr/local/lib/libboost_regex-gcc44-mt-d-1_41.so librt.so.1 = /usr/lib/hpux64/librt.so.1 libstdc++.so.6 = /opt/hp-gcc-4.4.0/lib/gcc/ia64-hp-hpux11.23/4.4.0/../../../hpux64/libstdc++.so.6 libm.so.1 = /usr/lib/hpux64/libm.so.1 libgcc_s.so.0 = /opt/hp-gcc-4.4.0/lib/gcc/ia64-hp-hpux11.23/4.4.0/../../../hpux64/libgcc_s.so.0 libunwind.so.1 = /usr/lib/hpux64/libunwind.so.1 librt.so.1 = /usr/lib/hpux64/librt.so.1 libm.so.1 = /usr/lib/hpux64/libm.so.1 libunwind.so.1 = /usr/lib/hpux64/libunwind.so.1 libdl.so.1 = /usr/lib/hpux64/libdl.so.1 libunwind.so.1 = /usr/lib/hpux64/libunwind.so.1 libc.so.1 = /usr/lib/hpux64/libc.so.1 libuca.so.1 = /usr/lib/hpux64/libuca.so.1 Looking at the stack trace, it seams odd that, although ldd list g++'s libstdc++ is being used, the std:string copy c'tor being reported as used is the one in libstd_v2, the implementation provided by aCC. The crash happens in the following code, when method str() returns: class JniString { std::string m_utf8; public: JniString(JNIEnv* env, jstring instance) { const char* utf8Chars = env-GetStringUTFChars(instance, 0); if (utf8Chars == 0) { env-ExceptionClear(); // RPF throw std::runtime_error("GetStringUTFChars returned 0"); } m_utf8.assign(utf8Chars); env-ReleaseStringUTFChars(instance, utf8Chars); } std::string str() const { return m_utf8; } }; Simultaneous usage of the two C++ implementations could likely be a reason for the crash, but that should not be happening. Any ideas?

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• Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

  - by Henrik

  Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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• Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

  - by Henrik

  Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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• Best way to handle multiple tables to replace one big table in Rails? (e.g. 'Books1', 'Books2', etc.

  - by mikep

  Hello, I've decided to use multiple tables for an entity (e.g. Books1, Books2, Books3, etc.), instead of just one main table which could end up having a lot of rows (e.g. just Books). I'm doing this to try and to avoid a potential future performance drop that could come with having too many rows in one table. With that, I'm looking for a good way to handle this in Rails, mainly by trying to avoid loading a bunch of unused associations. (I know that I could use a partition for this, but, for now, I've decided to go the 'multiple tables' route.) Each user has their books placed into a specific table. The actual book table is chosen when the user is created, and all of their books go into the same table. I'm going to split the adds across the tables. The goal is to try and keep each table pretty much even -- but that's a different issue. One thing I don't particularly want to have is a bunch of unused associations in the User class. Right now, it looks like I'd have to do the following: class User < ActiveRecord::Base has_many :books1, :books2, :books3, :books4, :books5 end class Books1 < ActiveRecord::Base belongs_to :user end class Books2 < ActiveRecord::Base belongs_to :user end class Books3 < ActiveRecord::Base belongs_to :user end I'm assuming that the main performance hit would come in terms of memory and possibly some method call overhead for each User object, since it has to load all of those associations, which in turn creates all of those nice, dynamic model accessor methods like User.find_by_. But for each specific user, only one of the book tables would be usable/applicable, since all of a user's books are stored in the same table. So, only one of the associations would be in use at any time and any other has_many :bookX association that was loaded would be a waste. For example, with a user.id of 2, I'd only need books3.find_by_author('Author'), but the way I'm thinking of setting this up, I'd still have access to Books1..n. I don't really know Ruby/Rails does internally with all of those has_many associations though, so maybe it's not so bad. But right now I'm thinking that it's really wasteful, and that there may just be a better, more efficient way of doing this. So, a few questions: 1) Is there's some sort of special Ruby/Rails methodology that could be applied to this 'multiple tables to represent one entity' scheme? Are there any 'best practices' for this? 2) Is it really bad to have so many unused has_many associations for each object? Is there a better way to do this? 3) Does anyone have any advice on how to abstract the fact that there's multiple book tables behind a single books model/class? For example, so I can call books.find_by_author('Author') instead of books3.find_by_author('Author'). Thank you!

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• Sockets server design advice

  - by Rob

  We are writing a socket server in c# and need some advice on the design. Background: Clients (from mobile devices) connect to our server app and we leave their socket open so we can send data back down to them whenever we need to. The amount of data varies but we generally send/receive data from each client every few seconds, so it's quite intensive. The amount of simultaneous connections can range from 50-500 (and more in the future). We have already written a server app using async sockets and it works, however we've come across some stumbling blocks and we need to make sure that what we're doing is correct. We have a collection which holds our client states (we have no socket/connection pool at the moment, should we?). Each time a client connects we create a socket and then wait for them to send us some data and in receiveCallBack we add their clientstate object to our connections dictionary (once we have verified who they are). When a client object then signs off we shutdown their socket and then close it as well as remove them from our collection of clients dictionary. Presumably everything happens in the right order, everything works as expected. However, almost everyday it stops accepting connections, or so we think, either that or it connects but doesn't actually do anything past that and we can't work out why it's just stopping. There are few things that we'r'e unsure about 1) Should we be creating some kind of connection pool as opposed to just a dictionary of client sockets 2) What happens to the sockets that connect but then don't get added to our dictionary, they just linger around in memory doing nothing, should we create ANOTHER dictionary that holds the sockets as soon as they are created? 3) What's the best way of finding if clients are no longer connected? We've read some many methods but we're not sure of the best one to use, send data or read data, if so how? 4) If we loop through the connections dictonary to check for disposed clients, should we be locking the dictionary, if so how does this affect other clients objects trying to use it at the same time, will it throw an error or just wait? 5) We often get disposedSocketException within ReceiveCallBack method at random times, does this mean we are safe to remove that socket from the collection? We can't seem to find any production type examples which show any of this working. Any advice would be greatly received

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