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  • Sync Vs. Async Sockets Performance in .NET

    - by Michael Covelli
    Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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  • Find the flaws in the concept...

    - by Trindaz
    A web based web browser. Sounds silly right? Here's a use case. All comments about what could go wrong, and if anyone has tried and failed at this, very much wanted User goes to www.theBrowser.com and logs in with credentials specific to theBrowser.com. User tells theBrowser what their username and password for various sites are User goes to theBrowser.com/?uri=somesite.com theBrowser sends off the http request with User's log in details, then sends the http response back to User. This lets theBrowser do weird and wonderful functions like change colours / style sheets / etc. to every site that gets passed through it. From a technical stand point, storing username and password and passing them along is not a challenge for one user, but if there were a few, I'd have to use some kind of server based browser software to store a session per user logged in at theBrowser.com. How could I do that? Will I have to start from scratch? Obviously privacy and security are issues. Would theBrowser.com be too great a risk, even if users are fully warned? Cheers, Dave

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  • Implementing A Static NSOutlineView

    - by spamguy
    I'm having a hard time scraping together enough snippets of knowledge to implement an NSOutlineView with a static, never-changing structure defined in an NSArray. This link has been great, but it's not helping me grasp submenus. I'm thinking they're just nested NSArrays, but I have no clear idea. Let's say we have an NSArray inside an NSArray, defined as NSArray *subarray = [[NSArray alloc] initWithObjects:@"2.1", @"2.2", @"2.3", @"2.4", @"2.5", nil]; NSArray *ovStructure = [[NSArray alloc] initWithObjects:@"1", subarray, @"3", nil]; The text is defined in outlineView:objectValueForTableColumn:byItem:. - (id)outlineView:(NSOutlineView *)ov objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)ovItem { if ([[[tableColumn headerCell] stringValue] compare:@"Key"] == NSOrderedSame) { // Return the key for this item. First, get the parent array or dictionary. // If the parent is nil, then that must be root, so we'll get the root // dictionary. id parentObject = [ov parentForItem:ovItem] ? [ov parentForItem:ovItem] : ovStructure; if ([parentObject isKindOfClass:[NSArray class]]) { // Arrays don't have keys (usually), so we have to use a name // based on the index of the object. NSLog([NSString stringWithFormat:@"%@", ovItem]); //return [NSString stringWithFormat:@"Item %d", [parentObject indexOfObject:ovItem]]; return (NSString *) [ovStructure objectAtIndex:[ovStructure indexOfObject:ovItem]]; } } else { // Return the value for the key. If this is a string, just return that. if ([ovItem isKindOfClass:[NSString class]]) { return ovItem; } else if ([ovItem isKindOfClass:[NSDictionary class]]) { return [NSString stringWithFormat:@"%d items", [ovItem count]]; } else if ([ovItem isKindOfClass:[NSArray class]]) { return [NSString stringWithFormat:@"%d items", [ovItem count]]; } } return nil; } The result is '1', '(' (expandable), and '3'. NSLog shows the array starting with '(', hence the second item. Expanding it causes a crash due to going 'beyond bounds.' I tried using parentForItem: but couldn't figure out what to compare the result to. What am I missing?

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  • MINA: Performing synchronous write requests / read responses

    - by Matt Huggins
    I'm attempting to perform a synchronous write/read in a demux-based client application with MINA 2.0 RC1, but it seems to get stuck. Here is my code: public boolean login(final String username, final String password) { // block inbound messages session.getConfig().setUseReadOperation(true); // send the login request final LoginRequest loginRequest = new LoginRequest(username, password); final WriteFuture writeFuture = session.write(loginRequest); writeFuture.awaitUninterruptibly(); if (writeFuture.getException() != null) { session.getConfig().setUseReadOperation(true); return false; } // retrieve the login response final ReadFuture readFuture = session.read(); readFuture.awaitUninterruptibly(); if (readFuture.getException() != null) { session.getConfig().setUseReadOperation(true); return false; } // stop blocking inbound messages session.getConfig().setUseReadOperation(false); // determine if the login info provided was valid final LoginResponse loginResponse = (LoginResponse)readFuture.getMessage(); return loginResponse.getSuccess(); } I can see on the server side that the LoginRequest object is retrieved, and a LoginResponse message is sent. On the client side, the DemuxingProtocolCodecFactory receives the response, but after throwing in some logging, I can see that the client gets stuck on the call to readFuture.awaitUninterruptibly(). I can't for the life of me figure out why it is stuck here based upon my own code. I properly set the read operation to true on the session config, meaning that messages should be blocked. However, it seems as if the message no longer exists by time I try to read response messages synchronously. Any clues as to why this won't work for me?

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  • Securely store a password in program code?

    - by Nick
    My application makes use of the RijndaelManaged class to encrypt data. As a part of this encryption, I use a SecureString object loaded with a password which get's get converted to a byte array and loaded into the RajindaelManaged object's Key at runtime. The question I have is the storage of this SecureString. A user entered password can be entered at run-time, and that can be "securely" loaded into a SecureString object, but if no user entered password is given, then I need to default to something. So ultimately the quesiton comes down to: If I have to have some known string or byte array to load into a SecureString object each time my application runs, how do I do that? The "encrypted" data ultimately gets decrypted by another application, so even if no user entered password is specified, I still need the data to be encrypted while it goes from one app to another. This means I can't have the default password be random, because the other app wouldn't be able to properly decrypt it. One possible solution I'm thinking is to create a dll which only spits out a single passphrase, then I use that passphrase and run it through a couple of different hashing/reorganizing functions at runtime before I ultimately feed it into the secureString object. Would this be secure enough?

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  • Extract wrong data from a frame in C?

    - by ipkiss
    I am writing a program that reads the data from the serial port on Linux. The data are sent by another device with the following frame format: |start | Command | Data | CRC | End | |0x02 | 0x41 | (0-127 octets) | | 0x03| ---------------------------------------------------- The Data field contains 127 octets as shown and octet 1,2 contains one type of data; octet 3,4 contains another data. I need to get these data. Because in C, one byte can only holds one character and in the start field of the frame, it is 0x02 which means STX which is 3 characters. So, in order to test my program, On the sender side, I construct an array as the frame formatted above like: char frame[254]; frame[0] = 0x02; // starting field frame[1] = 0x41; // command field which is character 'A' ..so on.. And, then On the receiver side, I take out the fields like: char result[254]; // read data read(result); printf("command = %c", result[1]); // get the command field of the frame // get other field's values the command field value (result[1]) is not character 'A'. I think, this because the first field value of the frame is 0x02 (STX) occupying 3 first places in the array frame and leading to the wrong results on the receiver side. How can I correct the issue or am I doing something wrong at the sender side? Thanks all. related questions: http://stackoverflow.com/questions/2500567/parse-and-read-data-frame-in-c http://stackoverflow.com/questions/2531779/clear-data-at-serial-port-in-linux-in-c

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  • Help with fql.multiQuery

    - by Daniel Schaffer
    I'm playing around with the Facebook API's fql.multiQuery method. I'm just using the API Test Console, and trying to get a successful response but can't seem to figure out exactly what it wants. Here's the text I'm entering into the "queries" field: {"tags" : "select subject from photo_tag where subject != 601599551 and pid in ( select pid from photo_tag where subject = 601599551 ) and subject in ( select uid2 from friend where uid1 = 601599551 )", "foo" : "select uid from user where uid = 601599551"} All it'll give me is a queries parameter: array expected. error. I've also tried just about every permutation I could think of involving wrapping the name/query pairs in their own curly braces, adding brackets, adding whitespace, removing whitespace in case it didn't want an associative array (for those watching the edits, I just found out about these wonderful things now... oy), all to no avail. Is there something painfully obvious I'm missing here, or do I need to make like Chuck Norris Jon Skeet and simply will it to do my bidding? Update: A note to anyone finding this question now: The fql.multiquery test console appears to be broken. You can test your query by clicking on the generated url in the test console and manually adding the "queries" parameter into the querystring.

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  • What is the relationship between Turing Machine & Modern Computer ? [closed]

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge between a conceptual Turing Machine and a modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • Zend Framework: Zend_translate and routing related issue

    - by Dan
    I have implemented Zend_Navigation, Zend_Translate in my application. The routing is setup in Bootstrap.php like below. $fc = Zend_Controller_Front::getInstance(); $zl=new Zend_Locale(); Zend_Registry::set('Zend_Locale',$zl); $lang=$zl->getLanguage().'_'.$zl->getRegion(); $router = $fc->getRouter(); $route = new Zend_Controller_Router_Route(':lang/:module/:controller/:action/*', array( 'lang'=>$lang, 'module'=>'default', 'controller'=>'index', 'action'=>'index' )); $router->addRoute('default', $route); $fc->setRouter($router); $fc->registerPlugin( new Plugin_LanguageSetup()); in LaunguageSetup Plugin i have defined the dispatchLoopStartup method to do the checking of the language param public function dispatchLoopStartup(Zend_Controller_Request_Abstract $request) { $this->createLangUrl($request); $this->_language = $request->getParam('lang'); if ((!isset($this->_language)) || !in_array($this->_language, $this->_languagesArray)) { $this->_language = 'en_US'; $request->setParam('lang', 'en_US'); } $file = APPLICATION_PATH.$this->_directory.$this->_language.'.csv'; $translate = new Zend_Translate('csv', $file, $this->_language); Zend_Registry::set('Zend_Translate', $translate); $zl = Zend_Registry::get('Zend_Locale'); $zl->setLocale($this->_language); Zend_Registry::set('Zend_Locale', $zl); // $fc = Zend_Controller_Front::getInstance(); // $router = $fc->getRouter(); // $route = new Zend_Controller_Router_Route(':lang/:module/:controller/:action/*', array( // 'lang'=>$this->_language, 'module'=>'default', 'controller'=>'index', 'action'=>'index' // )); // $router->addRoute('default', $route); // $fc->setRouter($router); } What happen is the language always have the default value, the 'lang' param never default lang value in route, even if i type it in the address bar manually i.e /en_US/module/controller/action/ It always get revert back to the default Zend_locale(); Only way i can fix it is to setup the route again in the plugin and inject a correct language value as default. Any Idea why?

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  • Cannot create instance of abstract class

    - by SmartestVEGA
    I am trying to compile the following code and i am getting the error: Cannot create instance of abstract class . Please help m_objExcel = new Excel.Application(); m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks; m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt)); m_objSheets = (Excel.Sheets)m_objBook.Worksheets; m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1)); // Create an array for the headers and add it to cells A1:C1. object[] objHeaders = {"Order ID", "Amount", "Tax"}; m_objRange = m_objSheet.get_Range("A1", "C1"); m_objRange.Value = objHeaders; m_objFont = m_objRange.Font; m_objFont.Bold=true; // Create an array with 3 columns and 100 rows and add it to // the worksheet starting at cell A2. object[,] objData = new Object[100,3]; Random rdm = new Random((int)DateTime.Now.Ticks); double nOrderAmt, nTax; for(int r=0;r<100;r++) { objData[r,0] = "ORD" + r.ToString("0000"); nOrderAmt = rdm.Next(1000); objData[r,1] = nOrderAmt.ToString("c"); nTax = nOrderAmt*0.07; objData[r,2] = nTax.ToString("c"); } m_objRange = m_objSheet.get_Range("A2", m_objOpt); m_objRange = m_objRange.get_Resize(100,3); m_objRange.Value = objData; // Save the Workbook and quit Excel. m_objBook.SaveAs(m_strSampleFolder + "Book2.xls", m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange, m_objOpt, m_objOpt, m_objOpt, m_objOpt); m_objBook.Close(false, m_objOpt, m_objOpt); m_objExcel.Quit();

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  • Filtering Wikipedia's XML dump: error on some accents

    - by streetpc
    I'm trying to index Wikpedia dumps. My SAX parser make Article objects for the XML with only the fields I care about, then send it to my ArticleSink, which produces Lucene Documents. I want to filter special/meta pages like those prefixed with Category: or Wikipedia:, so I made an array of those prefixes and test the title of each page against this array in my ArticleSink, using article.getTitle.startsWith(prefix). In English, everything works fine, I get a Lucene index with all the pages except for the matching prefixes. In French, the prefixes with no accent also work (i.e. filter the corresponding pages), some of the accented prefixes don't work at all (like Catégorie:), and some work most of the time but fail on some pages (like Wikipédia:) but I cannot see any difference between the corresponding lines (in less). I can't really inspect all the differences in the file because of its size (5 GB), but it looks like a correct UTF-8 XML. If I take a portion of the file using grep or head, the accents are correct (even on the incriminated pages, the <title>Catégorie:something</title> is correctly displayed by grep). On the other hand, when I rectreate a wiki XML by tail/head-cutting the original file, the same page (here Catégorie:Rock par ville) gets filtered in the small file, not in the original… Any idea ? Alternatives I tried: Getting the file (commented lines were tried wihtout success): FileInputStream fis = new FileInputStream(new File(xmlFileName)); //ReaderInputStream ris = ReaderInputStream.forceEncodingInputStream(fis, "UTF-8" ); //(custom function opening the stream, reading it as UFT-8 into a Reader and returning another byte stream) //InputSource is = new InputSource( fis ); is.setEncoding("UTF-8"); parser.parse(fis, handler); Filtered prefixes: ignoredPrefix = new String[] {"Catégorie:", "Modèle:", "Wikipédia:", "Cat\uFFFDgorie:", "Mod\uFFFDle:", "Wikip\uFFFDdia:", //invalid char "Catégorie:", "Modèle:", "Wikipédia:", // UTF-8 as ISO-8859-1 "Image:", "Portail:", "Fichier:", "Aide:", "Projet:"}; // those last always work

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  • Optimizing mathematics on arrays of floats in Ada 95 with GNATC

    - by mat_geek
    Consider the bellow code. This code is supposed to be processing data at a fixed rate, in one second batches, It is part of an overal system and can't take up too much time. When running over 100 lots of 1 seconds worth of data the program takes 35 seconds; or 35%. How do I improce the code to get the processing time down to a minimum? The code will be running on an Intel Pentium-M which is a P3 with SSE2. package FF is new Ada.Numerics.Generic_Elementary_Functions(Float); N : constant Integer := 820; type A is array(1 .. N) of Float; type A3 is array(1 .. 3) of A; procedure F(state : in out A3; result : out A3; l : in A; r : in A) is s : Float; t : Float; begin for i in 1 .. N loop t := l(i) + r(i); t := t / 2.0; state(1)(i) := t; state(2)(i) := t * 0.25 + state(2)(i) * 0.75; state(3)(i) := t * 1.0 /64.0 + state(2)(i) * 63.0 /64.0; for r in 1 .. 3 loop s := state(r)(i); t := FF."**"(s, 6.0) + 14.0; if t > MAX then t := MAX; elsif t < MIN then t := MIN; end if; result(r)(i) := FF.Log(t, 2.0); end loop; end loop; end;

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  • Optimal Serialization of Primitive Types

    - by Greg Dean
    We are beginning to roll out more and more WAN deployments of our product (.Net fat client w/ IIS hosted Remoting backend). Because of this we are trying to reduce the size of the data on the wire. We have overridden the default serialization by implementing ISerializable (similar to this), we are seeing anywhere from 12% to 50% gains. Most of our efforts focus on optimizing arrays of primitive types. I would like to know if anyone knows of any fancy way of serializing primitive types, beyond the obvious? For example today we serialize an array of ints as follows: [4-bytes (array length)][4-bytes][4-bytes] Can anyone do significantly better? The most obvious example of a significant improvement, for boolean arrays, is putting 8 bools in each byte, which we already do. Note: Saving 7 bits per bool may seem like a waste of time, but when you are dealing with large magnitudes of data (which we are), it adds up very fast. Note: We want to avoid general compression algorithms because of the latency associated with it. Remoting only supports buffered requests/responses(no chunked encoding). I realize there is a fine line between compression and optimal serialization, but our tests indicate we can afford very specific serialization optimizations at very little cost in latency. Whereas reprocessing the entire buffered response into new compressed buffer is too expensive.

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  • How to get top and left style property values in Javascript

    - by Dude-Dastic
    Hi all, I have a little bit of Javascript that almost works correctly. Here's the code: function toggle(curlink) { curlink.style.backgroundColor = curlink.style.backgroundColor == "yellow" ? "transparent" : "yellow"; var maindiv = document.getElementById("grid"); var links = maindiv.getElementsByTagName("a"); var list = ""; for (var i = 0; i < links.length; ++i) { var link = links[i]; if (link.style.backgroundColor == "yellow") { list += ("," + parseInt(link.style.left, 10) + "-" + parseInt(link.style.top, 10)); } } document.theForm.theList.value = list.substring(1); return false; }; window.onload = function() { var links = document.getElementById("grid").getElementsByTagName("a"); for (var i = 0; i < links.length; ++i) { links[i].onclick = function() { return toggle(this); } } }; The issue is with line #9; it only works when I specify values for the top and left style property of every link in the array. How do I get the top and left style property values (or X and Y coordinates) of each link in the array with Javascript when those values aren't given? Also, what would the code above look like in jquery? Not that it's needed - I just want to reduce the code a little and dabble in the jquery framework (I'm a Javascript newbie). Thanks in advance, Dude-Dastic

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  • Linux Lightweight Distro and X Windows for Development

    - by Fernando Barrocal
    Heyall... I want to build a lightweight linux configuration to use for development. The first idea is to use it inside a Virtual Machine under Windows, or old Laptops with 1Gb RAM top. Maybe even a distributable environment for developers. So the whole idea is to use a LAMP server, Java Application Server (Tomcat or Jetty) and X Windows (any Window manager, from FVWM to Enlightment), Eclipse, maybe jEdit and of course Firefox. Edit: I am changing this post to compile a possible list of distros and window managers that can be used to configure a real lightweight development environment. I am using as base personal experiences on this matter. Info about the distros can be easily found in their sites. So please, focus on personal use of those systems Distros Ubuntu / Xubuntu Pros: Personal Experience in old systems or low RAM environment - @Schroeder, @SCdF Several sugestions based on personal knowledge - @Kyle, @Peter Hoffmann Gentoo Pros: Not targeted to Desktop Users - @paan Don't come with a huge ammount of applications - @paan Slackware Pros: Suggested as best performance in a wise install/configuration - @Ryan Damn Small Linux Pros: Main focus is the lightweight factor - 50MB LiveCD - @Ryan Debian Pros: Very versatile, can be configured for both heavy and lightweight computers - @Ryan APT as package manager - @Kyle Based on compatibility and usability - @Kyle -- Fell Free to add Prós and Cons on this, so we can compile a good Reference. -- X Windows suggestion keep coming about XFCE. If others are to add here, open a session for it Like the distro one :)

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  • How to avoid "Illegal type in constant pool" using "ldc_w <classname>" in Jasmin?

    - by jazzdev
    I'm writing a compiler that generates Jasmin code and want to invoke a method that takes a Class as a parameter. public class CTest { public static void main(String[] args) throws Exception { java.lang.reflect.Array.newInstance(CTest.class, 0); } } So in Jasmin, I think that should be: .class public CTest2 .super java/lang/Object .method public static main([Ljava/lang/String;)V .limit stack 2 .limit locals 1 ldc_w CTest2 iconst_0 invokestatic java/lang/reflect/Array/newInstance(Ljava/lang/Class;I)Ljava/lang/Object; pop return .end method When I assemble it and run it I get: Exception in thread "main" java.lang.VerifyError: (class: CTest2, method: main signature: ([Ljava/lang/String;)V) Illegal type in constant pool Looking at the disassembled code for both CTest.class (the Java version) and CTest2.class (the Jasmin version) with "javap -c -verbose" they both appear to set up the constant pool the same way: const #2 = class #16; // CTest const #16 = Asciz CTest; 0: ldc_w #2; //class CTest const #14 = Asciz CTest2; const #17 = class #14; // CTest2 0: ldc_w #17; //class CTest2 I've fixed two bugs in Jasmin already, but I can't see what it's doing wrong when putting the class in the constant pool for "ldc_w" it puts classes in the constant pool for other instructions, like "new" and "anewarray" correctly. I've tried looking at the .class files with TraceClassVisitor in ASM, but it doesn't dump the constant pool. Any ideas what I can try next?

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  • Inconsistent get_class_methods vs method_exists when using UTF8 characters in PHP code

    - by coma
    I have this class in a UTF-8 encoded file called EnUTF8.Class.php: class EnUTF8 { public function ñññ() { return 'ñññ()'; } } and in another UTF-8 encoded file: require_once('EnUTF8.Class.php'); require_once('OneBuggy.Class.php'); $utf8 = new EnUTF8(); //$buggy = new OneBuggy(); echo (method_exists($utf8, 'ñññ')) ? 'ñññ() exists!' : 'ñññ() does not exist...'; echo "\n\n----------------------------------\n\n" print_r(get_class_methods($utf8)); echo "\n----------------------------------\n\n" echo $utf8->ñññ(); that produces the expected result: ñññ() exists! ---------------------------------- Array ( [0] => ñññ ) ---------------------------------- ñññ() but if... require_once('EnUTF8.Class.php'); require_once('OneBuggy.Class.php'); $utf8 = new EnUTF8(); $buggy = new OneBuggy(); echo (method_exists($utf8, 'ñññ')) ? 'ñññ() exists!' : 'ñññ() does not exist...'; echo "\n\n----------------------------------\n\n" print_r(get_class_methods($utf8)); echo "\n----------------------------------\n\n" echo $utf8->ñññ(); then the weirdness appears!!!: ñññ() does not exist! ---------------------------------- Array ( [0] => ñññ ) ---------------------------------- Fatal error: Call to undefined method EnUTF8::ñññ() in /var/www/test.php on line 16 Well, the thing is that OneBuggy.Class.php is UTF-8 encoded too and shares absolutly nothing with EnUTF8.Class.php so... where is the bug? UPDATED: Well, after a long debugging time I found this in OneBuggy.Class.php constructor: setlocale (LC_ALL, "es_ES@euro", "es_ES", "esp"); so I did... //setlocale (LC_ALL, "es_ES@euro", "es_ES", "esp"); and now it works but why?.

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  • Safe to update separate regions of a BufferedImage in separate threads?

    - by finnw
    I have a collection of BufferedImage instances, one main image and some subimages created by calling getSubImage on the main image. The subimages do not overlap. I am also making modifications to the subimage and I want to split this into multiple threads, one per subimage. From my understanding of how BufferedImage, Raster and DataBuffer work, this should be safe because: Each instance of BufferedImage (and its respective WritableRaster) is accessed from only one thread. The shared ColorModel is immutable The DataBuffer has no fields that can be modified (the only thing that can change is elements of the backing array.) Modifying disjoint segments of an array in separate threads is safe. However I cannot find anything in the documentation that says that it is definitely safe to do this. Can I assume it is safe? I know that it is possible to work on copies of the child Rasters but I would prefer to avoid this because of memory constraints. Otherwise, is it possible to make the operation thread-safe without copying regions of the parent image?

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  • TextBox should display text in hexadecimal in a specific format

    - by Owais Wani
    I have a textbox in my xaml file which is editable. Now according to my project requirements content in textbox should only be 0-9 and a-f (hexadecimal values) and textbox should take the input based on hexadecimal values. Demonstratation: 12 ab 32 a5 64 Now if my cursor is at the end and i go on pressing backspace, it shud remove the values as it happens in a general text box. Now If my cursor is at the beginning of a5, and i press "delete key", the value should become like: 12 ab 32 56 4 If my cursor is at the end of a5 and i press the 'delete key" nothing should happen. I had done this successful in my C++ application as follows: void CMSP430CommPanel::textEditorTextChanged (TextEditor& editor) { if(&editor == m_texti2cWrite) { int count = 0; int location; String text1 = m_texti2cWrite->getText(); String text = m_texti2cWrite->getText().removeCharacters(" "); String hexString = String::empty; int countCaret = m_texti2cWrite->getCaretPosition(); for(int i=0; i < text.length(); i++) { hexString = hexString + String (&text[i], 1); if((i+1) % 2 == 0) { if(i != text.length()-1) { hexString = hexString + T(" "); count ++; } } count ++; } m_texti2cWrite->setText(hexString,false); if(text1.length() == m_texti2cWrite->getCaretPosition()) { m_texti2cWrite->setCaretPosition(count); } else { m_texti2cWrite->setCaretPosition(countCaret); } } } where m_texti2cWrite is the name given to textbox. How can i implement the same case in my wpf application which is MVVM based. I have a textbox which shud take inputs as I said above. please help!!!

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  • How can I build something like Amazon S3 in Perl?

    - by Joel G
    I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe REST (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

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  • iPhone app stopped building crash reports

    - by BankStrong
    My app formerly created useful crash logs. I synced my iPhone in the past and found crash logs in library/logs/CrashReporter About a month ago, my app stopped creating crash reports. When I first discovered this problem, I assumed it was due to memory corruption (a possibility in my app). I just created a new project and added a crash to it. // Implement viewDidLoad to do additional setup after loading the view, // typically from a nib. - (void)viewDidLoad { NSMutableArray *array = [[NSMutableArray alloc] init]; [array removeObjectAtIndex:-1]; [super viewDidLoad]; } This app does not create a crash report either. Ideas I've started to explore: My phone is corrupted (tried restoring - somehow I brought it to the state from a few months ago) My XCode is corrupt (tried reinstalling, but current download demands Snow Leopard - and I can't upgrade to Snow Leopard online). This seems possible - I may have messed with device support around a month ago (similar to http://stackoverflow.com/questions/1224867/does-iphone-os-3-0-1-ruin-your-development-phone ) The location for crash logs has somehow moved. Suggestions?

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  • PHP set timeout for script with system call, set_time_limit not working

    - by tehalive
    I have a command-line PHP script that runs a wget request using each member of an array with foreach. This wget request can sometimes take a long time so I want to be able to set a timeout for killing the script if it goes past 15 seconds for example. I have PHP safemode disabled and tried set_time_limit(15) early in the script, however it continues indefinitely. Update: Thanks to Dor for pointing out this is because set_time_limit() does not respect system() calls. So I was trying to find other ways to kill the script after 15 seconds of execution. However, I'm not sure if it's possible to check the time a script has been running while it's in the middle of a wget request at the same time (a do while loop did not work). Maybe fork a process with a timer and set it to kill the parent after a set amount of time? Thanks for any tips! Update: Below is my relevant code. $url is passed from the command-line and is an array of multiple URLs (sorry for not posting this initially): foreach( $url as $key => $value){ $wget = "wget -r -H -nd -l 999 $value"; system($wget); }

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  • Empty POST from jQuery UI Dialog to PHP function with $.post

    - by solefald
    Hello, I am having hell of a time trying to figure this one out. Maybe someone can help me here or point me in the right direction. I have a jQuery UI dialog that pops up when user clicks on an image. The dialog displays a form with 2 drop down windows. "dept" and "group". Group drop down is disabled, until something is selected in the "dept" dropdown menu. When user selects a department, I do a POST to php function and then enable and populate the group drop down. Simple enough... <select name="dept" id="dept_select" onchange="getDeptGroups(this.value);"> // Some data here </select> JS function: function getDeptGroups(dept) { // This alert works and displays department name. //alert(dept); $.post("/am/ldap/getDepartmentGroups.php", { department: dept }, function(data){ alert(data); }); } and finally in php page i just do <? print_r($_POST); ?> and end up with empty array. Array ( ) This happens in both, Chrome and Firefox, however, FireBug clearly shows post data being submitted: What am i doing wrong here?

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  • Cloud-aware programming and help choosing a good framework

    - by Shoaibi
    How can i write a cloud-aware application? e.g. an application that takes benefit of being deployed on cloud. Is it same as an application that runs or a vps/dedicated server? if not then what are the differences? are there any design changes? What are the procedures that i need to take if i am to migrate an application to cloud-aware? Also i am about to implement a web application idea which would need features like security, performance, caching, and more importantly free. I have been comparing some frameworks and found that django has least RAM/CPU usage and works great in prefork+threaded mode, but i have also read that django based sites stop to respond with huge load of connections. Other frameworks that i have seen/know are Zend, CakePHP, Lithium/Cake3, CodeIgnitor, Symfony, Ruby on Rails.... So i would leave this to your opinion as well, suggest me a good free framework based on my needs. Finally thanks for reading the essay ;)

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  • Optimize existing code and need to list alphabetically.

    - by Brad
    I need help optimizing the code to run faster, unless it is optimized the best. I also want to alphabetize the list and I am unsure how to do that. It should be alphabetized by $userinfo[0]["sn"][0] I am using the adLDAP class: http://adldap.sourceforge.net/ <?php require_once('adLDAP.php'); //header('Content-type: text/json'); $adldap = new adLDAP(); $groupMembers = $adldap->group_members('STAFF'); //print_r($groupMembers); $userinfo = $adldap->user_info($username, array("givenname","sn","telephonenumber")); $displayname = $userinfo[0]["givenname"][0]." ".$userinfo[0]["sn"][0]; print "<ul>"; foreach ($groupMembers as $i => $username) { $userinfo = $adldap->user_info($username, array("*")); $displayname = "<strong>".$userinfo[0]["givenname"][0]." ".$userinfo[0]["sn"][0]."</strong> - ".$userinfo[0]["telephonenumber"][0]; if($userinfo[0]["sn"][0] != "" && $userinfo[0]["givenname"][0] != "" && $userinfo[0]["telephonenumber"][0] != "") { print "<li>".$displayname."</li>"; } } print "</ul>"; ?>

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