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  • Why am I seeing so many instantiable classes without state?

    - by futlib
    I'm seeing a lot of instantiable classes in the C++ and Java world that don't have any state. I really can't figure out why people do that, they could just use a namespace with free functions in C++, or a class with a private constructor and only static methods in Java. The only benefit I can think of is that you don't have to change most of your code if you later decide that you want a different implementation in certain situations. But isn't that a case of premature design? It could be turned into a class later, when/if it becomes appropriate. Am I getting this wrong? Is it not OOP if I don't put everything into objects (i.e. instantiated classes)? Then why are there so many utility namespaces and classes in the standard libraries of C++ and Java? Update: I've certainly seen a lot examples of this in my previous jobs, but I'm struggling to find open source examples, so maybe it's not that common after all. Still, I'm wondering why people do it, and how common it is.

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  • In developing a soap client proxy, which return structure is easier to use and more sensible?

    - by cori
    I'm writing (in PHP) a client/proxy for a SOAP web service. The return types are consistently wrapped in response objects that contain the return values. In many cases this make a lot of sense - for instance when multiple values are being returned: GetDetailsResponse Object ( Results Object ( [TotalResults] => 10 [NextPage] => 2 ) [Details] => Array ( [0] => Detail Object ( [Id] => 1 ) ) ) But some of the methods return a single scalar value or a single object or array wrapped in a response object: GetThingummyIdResponse Object ( [ThingummyId] => 42 ) In some cases these objects might be pretty deep, so getting at properties within requires drilling down several layers: $response->Details->Detail[0]->Contents->Item[5]->Id And if I unwrap them before passing them back I can strip out a layer from consumers' code. I know I'm probably being a little bit of an Architecture Astronaut here, but the latter style really bug me, so I've been working through my code to have my proxy methods just return the scalar value to the client code where there's no absolute need for a wrapper object. My question is, am I actually making things more difficult for the consumers of my code? Would I be better off just leaving the return values wrapped in response objects so that everything is consistent, or is removing unneccessary layers of indirection/abstraction worthwhile?

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  • Grub gives messages about the boot sector being used by other software. What should I do?

    - by Bobble
    This only happens with one of my computers. It is an elderly laptop that has had a long and varied history with several operating systems, but in its retirement it is acting as a server for my home network using Ubuntu 12.04. It is a single-boot system, there are no other systems installed. Every so often, whenever there is a grub upgrade, I notice a message like this: Setting up grub-common (1.99-21ubuntu3.4) ... Installing new version of config file /etc/grub.d/00_header ... Setting up grub2-common (1.99-21ubuntu3.4) ... Setting up grub-pc-bin (1.99-21ubuntu3.4) ... Setting up grub-pc (1.99-21ubuntu3.4) ... /usr/sbin/grub-setup: warn: Sector 32 is already in use by FlexNet; avoiding it. This software may cause boot or other problems in future. Please ask its authors not to store data in the boot track. Installation finished. No error reported. Should I be worried about this? What (if anything) should I do about it?

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  • Using the RadTransitionControl in Task-It

    Download Source Code NOTE: To run the source code provided your will need to update to the RC (release candidate) versions of Silverlight 4 and VisualStudio 2010.  In a recent Ask the Experts webinar I showed a simple solution that had similarities to one that I had used in my recent MVVM post, but had a few extra twists on it. I have since been asked if I could post the source code for this demo, so here it is (I am using similar techniques in my Task-It application). The database Before running the code for this app you will need to create the database. First, create a database called MVVMProject in SQL Server, then run MVVMProject.sql in the MVVMProjectDemo/Database directory of your downloaded .zip file. This should give you a Task table with 3 records in it. You will also need to update the connection string in web.config to point to your database ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Using the Coherence ConcurrentMap Interface (Locking API)

    - by jpurdy
    For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

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  • what will EcmaScript 6 bring to the table for us

    - by user697296
    Our company ported moderate chunks of business logic to JavaScript. We compile the code with a minifier, which further improves performance. Since the language is dynamically typed, it lends itself well to obfuscation, which occurs as a byproduct of minification. We went to great efforts to ensure it positively screams, performance-wise. We can now do what we did before, faster, better, with less code, on more platforms. In summary, we are very satisfied with the current state of the language. I personally love the language especially for its cross-platform nature. So naturally, I read up a lot about the state of JavaScript compilers, performance and compatibility across as many browsers and platforms as I have time to research. The one theme which has been growing louder and louder these days, is the news about ECMAScript 6. So far, what I have been able to gather is that ES6 promises a better development experience; firstly by enabling new ways to do things, secondly by reporting errors early. This sounds great for those who are still waiting for the language to meet their needs before jumping on board. But we have already jumped on board in a big way. Sure, I expect that we will have to do ongoing maintenance and feature revisions on our code through the years, and that we would obviously make use of best practices at the time. But I don't see us refactoring major portions of it to take advantage of language features that are mostly intended to boost developer productivity. I keep wondering, what impact will the language advances ultimately have on our existing, well-written, well-performing code base? Is there something I am missing? Is there something we ought to look out for? Does anyone have tips or guidance on how we should approach the ecmascript.next finalization? Should we care?

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  • Monday at Oracle OpenWorld 2012 - Must See Session: “Using the Right Tools, Techniques, and Technologies for Integration Projects”

    - by Lionel Dubreuil
    Don’t miss this “CON8669 - Using the Right Tools, Techniques, and Technologies for Integration Projects“ session with Timothy Hall - Sr. Director, Oracle: Date: Monday, Oct 1, Time: 3:15 PM - 4:15 PM Location: Moscone South - 308 Every integration project brings its own unique set of challenges. There are many tools and techniques to choose from. How do you ensure that you have a means of consistently and repeatedly making decisions about which tools, techniques, and technologies are used? In working with many customers around the globe, Oracle has developed a set of criteria to help evaluate a variety of common integration questions. This session explores these criteria and how they have been further organized into decision trees that offer a repeatable means for ensuring that project teams are given the same guidance from project to project. Using these techniques, the presentation shows how you can reduce risk and speed productivity for your projects Objectives for this session are to: Discuss common questions that arise at the start of integration projects Review various decision criteria and approaches for getting to a consistent set of answers Explore how these techniques can be used to reduce risk and speed productivity Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

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  • When uninstalling all GRUB packages for EC2 AMI build script, how do I bypass prompting?

    - by Skaperen
    When I try to uninstall all GRUB packages from the cloud-image version of Ubuntu I use in AWS EC2, I get an interactive prompt. I need put this all in a script under automation, so prompts need to be avoided. I have searched for means to bypass this, and all of the features like debconf apply to prompts for config settings which can be provided in advance. But the prompt I am getting is not a config prompt. It would be in the class of "are you sure" prompts. I tried --force-all and that did not work. The prompt is referring to the files in /boot/grub so I tried by first doing "rm -fr /boot/grub" (they do all go away) and it still prompts to ask me if I want to delete them even though there is nothing to delete. The wording of the prompt is: Do you want to have all GRUB 2 files removed from /boot/grub? This will make the system unbootable unless another boot loader is installed. Remove GRUB 2 from /boot/grub? <YES> <NO> The command I am doing is: dpkg --purge grub-common grub-gfxpayload-lists grub-legacy-ec2 grub-pc grub-pc-bin grub2-common How can I get past this prompt without trying to encapsulate it in something that tries to answer (which itself has issues when there is no TTY so I want to avoid that) ?

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  • Problem with understanding how to start

    - by Coolface
    Okay, this might be a little off-topic but i try anyway. Sorry to bother. So i'm working as sysadmin for at least 5 years now and i quite enjoy IT field in general. Somehow i was never interested in programming much but always want to learn something at least easy and for personal usage. As sysadmin i need scripting skills so learn shell scripting without much problems, i also try to learn pascal, delphi, basic over time and must recent was python. Well, my problem is when i try to learn programming i just can't apply what i learn from the books to the real word. What i mean is i understand there are data structures, algorithms, variables, lib's, if-then logic, etc. but i just can't understand how to apply this things when i want to do real things. Like i want to get a something simple as parse web page, i draw a quick algorithm like get a web page, find a word on it and write a to file, on the paper everything look simple but when i get to the coding i just stuck pretty much from the start. I try read code of the real programs that just totally confusing especially big parts with many classes so i'm just quickly lost a trail what this code do. I think i just lack some fundamentals to see a big picture but don't really know what this might be? Or maybe i just don't have a passion to programming at all... My best bet was a shell scripting so i have really no problems to write complex scripts but this just not enough. Recently i was read around 5 or 6 python books because everyone say it's so easy even kid can code something but still no much luck, python is good and easy but i can't make something harder then a prodecurial style code like in bash for easy things but when i want harder things i'm still stuck. In college i was also not a math and tech guy and like to study non-tech stuff mostly like economy, psychology maybe that my problem? Anyway any advice would be greatly appriciated.

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  • SDL blitting multiple surfaces at once

    - by extropic_engine
    I'm trying to write a platforming game where the sprites for the level backgrounds are broken up into 512x512 chunks. I keep 3 chunks in memory at a time and I'm trying to write code to blit all three to the screen. Here is the current code I have: SDL_Rect where; where.y = -game->camera->y; where.x = -game->camera->x - MAP_WIDTH; SDL_BlitSurface(left_chunk, NULL, screen, &where); where.x = -game->camera->x; SDL_BlitSurface(center_chunk, NULL, screen, &where); where.x = -game->camera->x + MAP_WIDTH; SDL_BlitSurface(right_chunk, NULL, screen, &where); The issue I'm running into is that whichever chunk gets blitted first is the only one that shows up. The rest fail to appear onscreen. I think the issue might have something to do with alpha transparency, but even if the chunks don't overlap at all they still fail to blit. In other parts of the code I'm blitting multiple things to the screen at once, such as characters and backgrounds, and they all show up correctly. This particular segment of code is the only area I'm encountering this problem. If I comment out the line that blits left_chunk, it changes to this:

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  • How to use Twitter4j With JSF2 for Login? [on hold]

    - by subodh
    I am trying to do login with Twitter and using Twitter4j for that and wrote this code In JSF <h:commandButton id="twitterbutton" value="Sign up with Twitter" action="#{twitterLoginBean.redirectTwitterLogin}" immediate="true" styleClass="twitterbutton"/> In ManagedBean public String redirectTwitterLogin() throws ServletException, IOException, TwitterException { HttpServletRequest request = (HttpServletRequest) FacesContext .getCurrentInstance().getExternalContext().getRequest(); HttpServletResponse response = (HttpServletResponse) FacesContext .getCurrentInstance().getExternalContext().getResponse(); Twitter twitter = TwitterFactory.getSingleton(); twitter.setOAuthConsumer(apiKey, apiSecret); RequestToken requestToken = twitter.getOAuthRequestToken(); if (requestToken != null) { AccessToken accessToken = null; BufferedReader br = new BufferedReader(new InputStreamReader( System.in)); while (null == accessToken) { try { String pin = br.readLine(); accessToken = twitter .getOAuthAccessToken(requestToken, pin); } catch (TwitterException te) { System.out .println("Failed to get access token, caused by: " + te.getMessage()); System.out.println("Retry input PIN"); } } request.setAttribute(IS_AUTHENTICATED, true); if (accessToken != null) { LOGGER.debug("We have a valid oauth token! Make the facebook request"); doApiCall(twitter, request, response); return null; } } else { LOGGER.debug("We don't have auth code yet, fetching the Authorization URL..."); String authorizationUrl = requestToken.getAuthorizationURL(); LOGGER.debug("Redirecting to the Authorization URL: {}", authorizationUrl); request.setAttribute(IS_AUTHENTICATED, false); redirect(authorizationUrl, response); return null; } return null; } In above code i want first Login window of twitter will show and then again same method will call and after user will login i can show user information userId,Handel,location etc. Redirect private void redirect(String url, HttpServletResponse response) throws IOException { String urlWithSessionID = response.encodeRedirectURL(url); response.sendRedirect(urlWithSessionID); } But this code is not working Can anyone tell better Solution for this ?

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  • jquery is not working over local network [migrated]

    - by Kortyell Davis
    i have a fedora server running apache web server. the server is connected to a home network. i have a laptop connected to the same network. i can enter the ip address of my server into the browser of my laptop and pull up the index.html file located in the document root directory of the fedora home server. the index.html file contains jquery code. the jquery code only works when i open it locally in my browser (e.g. right click open with firefox), but when i attempt to view the webpage from my laptop the jquery code is not executed. the code is here below. <script type="text/javascript" src="jquery-1.8.2.js"></script> ' $(document).ready(function() { $('#form').hide(); $('input[type=text]').focus(function() { $(this).val(''); }); $('input[type=password]').focus(function() { $(this).val(''); }); $('.form').hide(); $('#log').click(function(){ $('#form').toggle(); }); $('#reg').click(function(){ $('.form').toggle(); }); });

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  • ?????????????????:???????Oracle Solaris Studio 12.3?

    - by kazun
    2011?12?16??????????????????????? Oracle Solaris Studio 12.3 ??????????? Oracle Solaris Studio 12.3 ??C?C++?Fortran?????????????????????????????·??????????SPARC T4?x86??????????????????????????????300%??????????????????Studio 12.3 ?Oracle Solaris?Oracle Linux?Red Hat Enterprise Linux ???????????????????????? ??????Oracle Solaris Studio 12.3???????????????????? Oracle Solaris Studio 12.3 ?3?????? - ?????????????????????????? - ??????? - ??????·??????????????? Oracle Solaris Studio 12.3 ??? ???????????????? SPARC-T4???????????GCC???????300%, x86??????150%????????????????Sun Studio 12??????SPARC-T4?40%?x86?20%??????????????? ???????????????? ?????????????????????????????????Code Analyzer??????????????????????????????????????????Performance Analyzer???????????????????????????????????? ???????? Oracle Solaris?Oracle Linux??OS??????????????????????????·???????????????????????????????????????????????????20%???????????????????????????????·??????(SSH??)???????????Oracle Solaris?Linux?Windows?Mac OS?????????Oracle Solaris?Linux??????????????????????????????????????????·??????????????????Oracle Database????????????????????Pro*C ??????Oracle Solaris Studio?????????? Oracle Solaris Studio 12.3 ??? ?:Oracle Solaris Studio ??? Compiler Suite C/C++?Fortran ??????????????????????????(?????????????????)?????????????????·???????????????????????????????????????????? Analysis Suite ?Performance Analyzer??Code Analyzer??Thread Analyzer??3???????????????Code Analyzer?????????????????·???????????????????????????Performance Analyzer??????????????????????????????·??????????????????????????????????????Thread Analyzer????????????????????????????Solaris ?????P-?????OpenMP3.1???????????????????????????????????????????????????????????????????????????????????? ?:Code Analyzer ?????IDE?? ?Oracle Solaris Studio????????????(IDE)???????NetBeans???????????????????Oracle DB?MySQL???????Pro*C?OCI????????????????????????????·??????????????????????????????????????????????????????????????????????????????? Oracle Solaris Studio 12.3???? ???????????????Solaris Studio 12.3???????????????????????·?????????????????·??????????????????????????????? ??????????? ?Oracle Solaris Studio 12.3???????????????? ?????? Solaris Studio 12.3 ????????? ?????? ??????????????????????????????????????Solaris Studio ??????????????????????????????????????Oracle Solaris Studio ??????????????????? Oracle Solaris Studio Oracle Solaris

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  • Implements EAN13 and UPC-A barcode in PDF using fpdf in classic ASP

    - by Jeremy N
    /* FPDF library for ASP can be downloaded from: http://www.aspxnet.it/public/default.asp INFORMATIONS: Translated by: Jeremy Author: Olivier License: Freeware DESCRIPTION: This script implements EAN13 and UPC-A barcodes (the second being a particular case of the first one). Bars are drawn directly in the PDF (no image is generated) function EAN13(x,y,barcode,h,w) -x = x coordinate to start drawing the barcode -y = y coordinate to start drawing the barcode -barcode = code to write (must be all numeric) -h = height of the bar -w = the minimum width of individual bar function UPC_A(x,y,barcode,h,w) Same parameters An EAN13 barcode is made up of 13 digits, UPC-A of 12 (leading zeroes are added if necessary). The last digit is a check digit; if it's not supplied or if it is incorrect, it will be automatically computed. USAGE: Copy all of this text and save it in a file called barcode.ext file under fpdf/extends folder EXAMPLE: Set pdf=CreateJsObject("FPDF") pdf.CreatePDF "P","mm","letter" pdf.SetPath("fpdf/") pdf.LoadExtension("barcode") pdf.Open() pdf.AddPage() 'set the fill color to black pdf.setfillcolor 0,0,0 pdf.UPC_A 80,40,"123456789012",16,0.35 pdf.Close() pdf.NewOutput "" , true, "test.pdf" */ this.EAN13=function (x,y,barcode,h,w) { return this.Barcode(x,y,barcode,h,w,13); }; this.UPC_A=function (x,y,barcode,h,w) { return this.Barcode(x,y,barcode,h,w,12); }; function GetCheckDigit(barCode) { bc = barCode.replace(/[^0-9]+/g,''); total = 0; //Get Odd Numbers for (i=bc.length-1; i=0; i=i-2) { total = total + parseInt(bc.substr(i,1)); } //Get Even Numbers for (i=bc.length-2; i=0; i=i-2) { temp = parseInt(bc.substr(i,1)) * 2; if (temp 9) { tens = Math.floor(temp/10); ones = temp - (tens*10); temp = tens + ones; } total = total + temp; } //Determine the checksum modDigit = (10 - total % 10) % 10; return modDigit.toString(); } //Test validity of check digit function TestCheckDigit(barcode) { var cd=GetCheckDigit(barcode.substring(0,barcode.length-1)); return cd==parseInt(barcode.substring(barcode.length-1,1)); } this.Barcode=function Barcode(x,y,barcode,h,w,len) { //Padding while(barcode.length < len-1) { barcode = '0' + barcode; } if(len==12) {barcode='0' + barcode;} //Add or control the check digit if(barcode.length==12) { barcode += GetCheckDigit(barcode); } else { //if the check digit is incorrect, fix the check digit. if(!TestCheckDigit(barcode)) { barcode = barcode.substring(0,barcode.length-1) + GetCheckDigit(barcode.substring(0,barcode.length-1)); } } //Convert digits to bars var codes=[['0001101','0011001','0010011','0111101','0100011','0110001','0101111','0111011','0110111','0001011'], ['0100111','0110011','0011011','0100001','0011101','0111001','0000101','0010001','0001001','0010111'], ['1110010','1100110','1101100','1000010','1011100','1001110','1010000','1000100','1001000','1110100'] ]; var parities=[[0,0,0,0,0,0], [0,0,1,0,1,1], [0,0,1,1,0,1], [0,0,1,1,1,0], [0,1,0,0,1,1], [0,1,1,0,0,1], [0,1,1,1,0,0], [0,1,0,1,0,1], [0,1,0,1,1,0], [0,1,1,0,1,0] ]; var code='101'; var p=parities[parseInt(barcode.substr(0,1))]; var i; for(i=1;i<=6;i++) { code+= codes[p[i-1]][parseInt(barcode.substr(i,1))]; } code+='01010'; for(i=7;i<=12;i++) { code+= codes[2][parseInt(barcode.substr(i,1))]; } code+='101'; //Draw bars for(i=0;i<code.length;i++) { if(code.substr(i,1)=='1') { this.Rect(x+i*w,y,w,h,'F'); } } //Print text uder barcode. this.SetFont('Arial','',12); //Set the x so that the font is centered under the barcode this.Text(x+parseInt(0.5*barcode.length)*w,y+h+11/this.k,barcode.substr(barcode.length-len,len)); }

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  • no namenode error in pseudo-mode

    - by Anshu Basia
    I'm new to hadoop and is in learning phase. As per Hadoop Definitve guide, i have set up my hadoop in pseudo distributed mode and everything was working fine. I was even able to execute all the examples from chapter 3 yesterday. Today, when i rebooted my unix and tried to run start-dfs.sh and then tried http://localhost/50070....it is showing error and when i try to stop dfs (stop-dfs.sh) it says no namenode to stop. I have been googling the issue but no result. Also, when i format my namenode again...everything starts working fine and i'm able to connect to the localhost/50070 and even replicate files and directories in hdfs but as soon as i restart my linux and try to connect to hdfs the same problem comes up. Below is the error log: ************************************************************/ 2011-06-22 15:45:55,249 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: STARTUP_MSG: /************************************************************ STARTUP_MSG: Starting NameNode STARTUP_MSG: host = ubuntu/127.0.1.1 STARTUP_MSG: args = [] STARTUP_MSG: version = 0.20.203.0 STARTUP_MSG: build = http://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-203 -r 1099333; compiled by 'oom' on Wed May 4 07:57:50 PDT 2011 ************************************************************/ 2011-06-22 15:45:56,383 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties 2011-06-22 15:45:56,455 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source MetricsSystem,sub=Stats registered. 2011-06-22 15:45:56,494 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s). 2011-06-22 15:45:56,494 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started 2011-06-22 15:45:57,007 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source ugi registered. 2011-06-22 15:45:57,031 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists! 2011-06-22 15:45:57,059 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source jvm registered. 2011-06-22 15:45:57,070 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source NameNode registered. 2011-06-22 15:45:57,374 INFO org.apache.hadoop.hdfs.util.GSet: VM type = 32-bit 2011-06-22 15:45:57,374 INFO org.apache.hadoop.hdfs.util.GSet: 2% max memory = 19.33375 MB 2011-06-22 15:45:57,374 INFO org.apache.hadoop.hdfs.util.GSet: capacity = 2^22 = 4194304 entries 2011-06-22 15:45:57,374 INFO org.apache.hadoop.hdfs.util.GSet: recommended=4194304, actual=4194304 2011-06-22 15:45:57,854 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: fsOwner=anshu 2011-06-22 15:45:57,854 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: supergroup=supergroup 2011-06-22 15:45:57,854 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isPermissionEnabled=true 2011-06-22 15:45:57,868 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: dfs.block.invalidate.limit=100 2011-06-22 15:45:57,869 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s) 2011-06-22 15:45:58,769 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Registered FSNamesystemStateMBean and NameNodeMXBean 2011-06-22 15:45:58,809 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Caching file names occuring more than 10 times **2011-06-22 15:45:58,825 INFO org.apache.hadoop.hdfs.server.common.Storage: Storage directory /tmp/hadoop-anshu/dfs/name does not exist. 2011-06-22 15:45:58,827 ERROR org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem initialization failed. org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /tmp/hadoop-anshu/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible. at org.apache.h**adoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:291) at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:97) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:379) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:353) at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:254) at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:434) at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1153) at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1162) 2011-06-22 15:45:58,828 ERROR org.apache.hadoop.hdfs.server.namenode.NameNode: org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /tmp/hadoop-anshu/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible. at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:291) at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:97) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:379) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:353) at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:254) at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:434) at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1153) at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1162) 2011-06-22 15:45:58,829 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down NameNode at ubuntu/127.0.1.1 ************************************************************/ Any help is appreciated Thank-you

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  • Android: get current location from best available provider

    - by AP257
    Hi all, I have some Android code that needs to get the best available location QUICKLY, from GPS, network or whatever is available. Accuracy is less important than speed. Getting the best available location is surely a really standard task. Yet I can't find any code to demonstrate it. The Android location code expects you to specify criteria, register for updates, and wait - which is fine if you have detailed criteria and don't mind waiting around. But my app needs to work a bit more like the Maps app does when it first locates you - work from any available provider, and just check the location isn't wildly out of date or null. I've attempted to roll my own code to do this, but am having problems. (It's inside an IntentService where an upload happens, if that makes any difference. I've included all the code for info.) What's wrong with this code? @Override protected void onHandleIntent(Intent arg0) { testProviders(); doUpload(); } private boolean doUpload() { int j = 0; // check if we have accurate location data yet - wait up to 30 seconds while (j < 30) { if ((latString == "") || (lonString == "")) { Log.d(LOG_TAG, "latlng null"); Thread.sleep(1000); j++; } else { Log.d(LOG_TAG, "found lat " + latString + " and lon " + lonString); break; } //do the upload here anyway, with or without location data //[code removed for brevity] } public boolean testProviders() { Log.e(LOG_TAG, "testProviders"); String location_context = Context.LOCATION_SERVICE; locationmanager = (LocationManager) getSystemService(location_context); List<String> providers = locationmanager.getProviders(true); for (String provider : providers) { Log.e(LOG_TAG, "registering provider " + provider); listener = new LocationListener() { public void onLocationChanged(Location location) { // keep checking the location - until we have // what we need //if (!checkLoc(location)) { Log.e(LOG_TAG, "onLocationChanged"); locationDetermined = checkLoc(location); //} } public void onProviderDisabled(String provider) { } public void onProviderEnabled(String provider) { } public void onStatusChanged(String provider, int status, Bundle extras) { } }; locationmanager.requestLocationUpdates(provider, 0, 0, listener); } Log.e(LOG_TAG, "getting updates"); return true; } private boolean checkLoc(Location location) { float tempAccuracy = location.getAccuracy(); int locAccuracy = (int) tempAccuracy; Log.d(LOG_TAG, "locAccuracy = " + locAccuracy); if ((locAccuracy != 0) && (locAccuracy < LOCATION_ACCURACY)) { latitude = location.getLatitude(); longitude = location.getLongitude(); latString = latitude.toString(); lonString = longitude.toString(); return true; } return false; } public void removeListeners() { // Log.e(LOG_TAG, "removeListeners"); if ((locationmanager != null) && (listener != null)) { locationmanager.removeUpdates(listener); } locationmanager = null; // Log.d(LOG_TAG, "Removed " + listener.toString()); } @Override public void onDestroy() { super.onDestroy(); removeListeners(); } Unfortunately, this finds the network provider, but only ever outputs latlng null 30 times - it never seems to get a location at all. I never even get a log statement of locationChanged. It's funny, because from ddms I can see output like: NetworkLocationProvider: onCellLocationChanged [305,8580] NetworkLocationProvider: getNetworkLocation(): returning cache location with accuracy 75.0 seeming to suggest that the network provider does have some location info after all, I'm just not getting at it. Can anyone help? I think working example code would be a useful resource for the Android/StackOverflow community.

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  • Connection to webservice times out first time

    - by Neo
    My application needs to connect to a web service. The WSDL file given by the client was converted to java using the wsdl2java utility in axis 2-1.5.2. The problem occurs during the first connection to the webservice. It gives me java.net.SocketTimeoutException: Read timed out at jrockit.net.SocketNativeIO.readBytesPinned(Native Method) at jrockit.net.SocketNativeIO.socketRead(SocketNativeIO.java:46) at java.net.SocketInputStream.socketRead0(SocketInputStream.java) at java.net.SocketInputStream.read(SocketInputStream.java:129) at com.sun.net.ssl.internal.ssl.InputRecord.readFully(InputRecord.java:293) at com.sun.net.ssl.internal.ssl.InputRecord.read(InputRecord.java:331) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:789) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:747) at com.sun.net.ssl.internal.ssl.AppInputStream.read(AppInputStream.java:75) at java.io.BufferedInputStream.fill(BufferedInputStream.java:218) at java.io.BufferedInputStream.read(BufferedInputStream.java:238) at org.apache.commons.httpclient.HttpParser.readRawLine(HttpParser.java:78) at org.apache.commons.httpclient.HttpParser.readLine(HttpParser.java:106) at org.apache.commons.httpclient.HttpConnection.readLine(HttpConnection.java:1116) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.readLine(MultiThreadedHttpConnectionManager.java:1413) at org.apache.commons.httpclient.HttpMethodBase.readStatusLine(HttpMethodBase.java:1974) at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodBase.java:1735) at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:1100) at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:398) at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171) at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397) at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:346) at org.apache.axis2.transport.http.AbstractHTTPSender.executeMethod(AbstractHTTPSender.java:558) at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:199) at org.apache.axis2.transport.http.HTTPSender.send(HTTPSender.java:77) at org.apache.axis2.transport.http.CommonsHTTPTransportSender.writeMessageWithCommons(CommonsHTTPTransportSender.java:400) at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:225) at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:438) at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:402) at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:230) at org.apache.axis2.client.OperationClient.execute(OperationClient.java:166) at com.jmango.webservice.talker.WCFServiceStub.addSaleSupportRequest(WCFServiceStub.java:270) at com.jmango.domain.salessystem.talkerimp.RequestServiceInfoImp.addanewServiceRequest(RequestServiceInfoImp.java:58) at com.jmango.mobilenexus.service.MobileServiceImp.sendQueryforServiceInfo(MobileServiceImp.java:358) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.springframework.remoting.support.RemoteInvocationTraceInterceptor.invoke(RemoteInvocationTraceInterceptor.java:77) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) at $Proxy8.sendQueryforServiceInfo(Unknown Source) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:180) at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:110) at org.springframework.remoting.caucho.Hessian2SkeletonInvoker.invoke(Hessian2SkeletonInvoker.java:94) at org.springframework.remoting.caucho.HessianExporter.invoke(HessianExporter.java:142) at org.springframework.remoting.caucho.HessianServiceExporter.handleRequest(HessianServiceExporter.java:70) at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:50) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:807) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:512) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:718) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:111) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190) at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291) at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:776) at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:705) at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:899) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690) at java.lang.Thread.run(Thread.java:619) I tried searching the web for answers though there was one place which mentions it could be the firewall at the webservice end that is blocking, I wasnt able to find a valid solution. Any help will be much appreciated. Running: Apache Tomcat 6.0 Axis2 1.5.2

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  • CUDA not working in 64 bit windows 7

    - by Programmer
    I have cuda toolkit 4.0 installed in a 64 bit windows 7. I try building my cuda code, #include<iostream> #include"cuda_runtime.h" #include"cuda.h" __global__ void kernel(){ } int main(){ kernel<<<1,1>>>(); int c = 0; cudaGetDeviceCount(&c); cudaDeviceProp prop; cudaGetDeviceProperties(&prop, 0); std::cout<<"the name is"<<prop.name; std::cout<<"Hello World!"<<c<<std::endl; system("pause"); return 0; } but operation fails. Below is the build log: Build Log Rebuild started: Project: god, Configuration: Debug|Win32 Command Lines Creating temporary file "c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\Debug\BAT0000482007500.bat" with contents [ @echo off echo "C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" -gencode=arch=compute_20,code=\"sm_20,compute_20\" --machine 32 -ccbin "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\bin" -Xcompiler "/EHsc /W3 /nologo /O2 /Zi /MT " -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\include" -maxrregcount=0 --compile -o "Debug/sample.cu.obj" sample.cu "C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" -gencode=arch=compute_20,code=\"sm_20,compute_20\" --machine 32 -ccbin "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\bin" -Xcompiler "/EHsc /W3 /nologo /O2 /Zi /MT " -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\include" -maxrregcount=0 --compile -o "Debug/sample.cu.obj" "c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\sample.cu" if errorlevel 1 goto VCReportError goto VCEnd :VCReportError echo Project : error PRJ0019: A tool returned an error code from "Compiling with CUDA Build Rule..." exit 1 :VCEnd ] Creating command line """c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\Debug\BAT0000482007500.bat""" Creating temporary file "c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\Debug\RSP0000492007500.rsp" with contents [ /OUT:"C:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\Debug\god.exe" /LIBPATH:"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\lib\x64" /MANIFEST /MANIFESTFILE:"Debug\god.exe.intermediate.manifest" /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /DEBUG /PDB:"C:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\Debug\god.pdb" /DYNAMICBASE /NXCOMPAT /MACHINE:X86 cudart.lib cuda.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib ".\Debug\sample.cu.obj" ] Creating command line "link.exe @"c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\Debug\RSP0000492007500.rsp" /NOLOGO /ERRORREPORT:PROMPT" Output Window Compiling with CUDA Build Rule... "C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" -gencode=arch=compute_20,code=\"sm_20,compute_20\" --machine 32 -ccbin "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\bin" -Xcompiler "/EHsc /W3 /nologo /O2 /Zi /MT " -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.0\include" -maxrregcount=0 --compile -o "Debug/sample.cu.obj" sample.cu sample.cu sample.cu.obj : error LNK2019: unresolved external symbol _cudaLaunch@4 referenced in function "enum cudaError cdecl cudaLaunch(char *)" (??$cudaLaunch@D@@YA?AW4cudaError@@PAD@Z) sample.cu.obj : error LNK2019: unresolved external symbol ___cudaRegisterFunction@40 referenced in function "void __cdecl _sti_cudaRegisterAll_52_tmpxft_00001c68_00000000_8_sample_compute_10_cpp1_ii_b81a68a1(void)" (?sti__cudaRegisterAll_52_tmpxft_00001c68_00000000_8_sample_compute_10_cpp1_ii_b81a68a1@@YAXXZ) sample.cu.obj : error LNK2019: unresolved external symbol _cudaRegisterFatBinary@4 referenced in function "void __cdecl _sti_cudaRegisterAll_52_tmpxft_00001c68_00000000_8_sample_compute_10_cpp1_ii_b81a68a1(void)" (?sti__cudaRegisterAll_52_tmpxft_00001c68_00000000_8_sample_compute_10_cpp1_ii_b81a68a1@@YAXXZ) sample.cu.obj : error LNK2019: unresolved external symbol _cudaGetDeviceProperties@8 referenced in function _main sample.cu.obj : error LNK2019: unresolved external symbol _cudaGetDeviceCount@4 referenced in function _main sample.cu.obj : error LNK2019: unresolved external symbol _cudaConfigureCall@32 referenced in function _main C:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\Debug\god.exe : fatal error LNK1120: 7 unresolved externals Results Build log was saved at "file://c:\Users\t-sudhk\Documents\Visual Studio 2008\Projects\god\god\Debug\BuildLog.htm" god - 8 error(s), 0 warning(s) I will be highly obliged if someone could help me. Thanks

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  • Servlet/JSP Flow Control: Enums, Exceptions, or Something Else?

    - by Christopher Parker
    I recently inherited an application developed with bare servlets and JSPs (i.e.: no frameworks). I've been tasked with cleaning up the error-handling workflow. Currently, each <form> in the workflow submits to a servlet, and based on the result of the form submission, the servlet does one of two things: If everything is OK, the servlet either forwards or redirects to the next page in the workflow. If there's a problem, such as an invalid username or password, the servlet forwards to a page specific to the problem condition. For example, there are pages such as AccountDisabled.jsp, AccountExpired.jsp, AuthenticationFailed.jsp, SecurityQuestionIncorrect.jsp, etc. I need to redesign this system to centralize how problem conditions are handled. So far, I've considered two possible solutions: Exceptions Create an exception class specific to my needs, such as AuthException. Inherit from this class to be more specific when necessary (e.g.: InvalidUsernameException, InvalidPasswordException, AccountDisabledException, etc.). Whenever there's a problem condition, throw an exception specific to the condition. Catch all exceptions via web.xml and route them to the appropriate page(s) with the <error-page> tag. enums Adopt an error code approach, with an enum keeping track of the error code and description. The descriptions can be read from a resource bundle in the finished product. I'm leaning more toward the enum approach, as an authentication failure isn't really an "exceptional condition" and I don't see any benefit in adding clutter to the server logs. Plus, I'd just be replacing one maintenance headache with another. Instead of separate JSPs to maintain, I'd have separate Exception classes. I'm planning on implementing "error" handling in a servlet that I'm writing specifically for this purpose. I'm also going to eliminate all of the separate error pages, instead setting an error request attribute with the error message to display to the user and forwarding back to the referrer. Each target servlet (Logon, ChangePassword, AnswerProfileQuestions, etc.) would add an error code to the request and redirect to my new servlet in the event of a problem. My new servlet would look something like this: public enum Error { INVALID_PASSWORD(5000, "You have entered an invalid password."), ACCOUNT_DISABLED(5002, "Your account has been disabled."), SESSION_EXPIRED(5003, "Your session has expired. Please log in again."), INVALID_SECURITY_QUESTION(5004, "You have answered a security question incorrectly."); private final int code; private final String description; Error(int code, String description) { this.code = code; this.description = description; } public int getCode() { return code; } public String getDescription() { return description; } }; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String sendTo = "UnknownError.jsp"; String message = "An unknown error has occurred."; int errorCode = Integer.parseInt((String)request.getAttribute("errorCode"), 10); Error errors[] = Error.values(); Error error = null; for (int i = 0; error == null && i < errors.length; i++) { if (errors[i].getCode() == errorCode) { error = errors[i]; } } if (error != null) { sendTo = request.getHeader("referer"); message = error.getDescription(); } request.setAttribute("error", message); request.getRequestDispatcher(sendTo).forward(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } Being fairly inexperienced with Java EE (this is my first real exposure to JSPs and servlets), I'm sure there's something I'm missing, or my approach is suboptimal. Am I on the right track, or do I need to rethink my strategy?

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  • Preventing multiple repeat selection of synchronized Controls ?

    - by BillW
    The working code sample here synchronizes (single) selection in a TreeView, ListView, and ComboBox via the use of lambda expressions in a dictionary where the Key in the dictionary is a Control, and the Value of each Key is an Action<int. Where I am stuck is that I am getting multiple repetitions of execution of the code that sets the selection in the various controls in a way that's unexpected : it's not recursing : there's no StackOverFlow error happening; but, I would like to figure out why the current strategy for preventing multiple selection of the same controls is not working. Perhaps the real problem here is distinguishing between a selection update triggered by the end-user and a selection update triggered by the code that synchronizes the other controls ? Note: I've been experimenting with using Delegates, and forms of Delegates like Action<T>, to insert executable code in Dictionaries : I "learn best" by posing programming "challenges" to myself, and implementing them, as well as studying, at the same time, the "golden words" of luminaries like Skeet, McDonald, Liberty, Troelsen, Sells, Richter. Note: Appended to this question/code, for "deep background," is a statement of how I used to do things in pre C#3.0 days where it seemed like I did need to use explicit measures to prevent recursion when synchronizing selection. Code : Assume a WinForms standard TreeView, ListView, ComboBox, all with the same identical set of entries (i.e., the TreeView has only root nodes; the ListView, in Details View, has one Column). private Dictionary<Control, Action<int>> ControlToAction = new Dictionary<Control, Action<int>>(); private void Form1_Load(object sender, EventArgs e) { // add the Controls to be synchronized to the Dictionary // with appropriate Action<int> lambda expressions ControlToAction.Add(treeView1, (i => { treeView1.SelectedNode = treeView1.Nodes[i]; })); ControlToAction.Add(listView1, (i => { listView1.Items[i].Selected = true; })); ControlToAction.Add(comboBox1, (i => { comboBox1.SelectedIndex = i; })); } private void synchronizeSelection(int i, Control currentControl) { foreach(Control theControl in ControlToAction.Keys) { // skip the 'current control' if (theControl == currentControl) continue; // for debugging only Console.WriteLine(theControl.Name + " synchronized"); // execute the Action<int> associated with the Control ControlToAction[theControl](i); } } private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { synchronizeSelection(e.Node.Index, treeView1); } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { synchronizeSelection(listView1.SelectedIndices[0], listView1); } } private void comboBox1_SelectedValueChanged(object sender, EventArgs e) { if (comboBox1.SelectedIndex > -1) { synchronizeSelection(comboBox1.SelectedIndex, comboBox1); } } background : pre C# 3.0 Seems like, back in pre C# 3.0 days, I was always using a boolean flag to prevent recursion when multiple controls were updated. For example, I'd typically have code like this for synchronizing a TreeView and ListView : assuming each Item in the ListView was synchronized with a root-level node of the TreeView via a common index : // assume ListView is in 'Details View,' has a single column, // MultiSelect = false // FullRowSelect = true // HideSelection = false; // assume TreeView // HideSelection = false // FullRowSelect = true // form scoped variable private bool dontRecurse = false; private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { if(dontRecurse) return; dontRecurse = true; listView1.Items[e.Node.Index].Selected = true; dontRecurse = false; } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { if(dontRecurse) return // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { dontRecurse = true; treeView1.SelectedNode = treeView1.Nodes[listView1.SelectedIndices[0]]; dontRecurse = false; } } Then it seems, somewhere around FrameWork 3~3.5, I could get rid of the code to suppress recursion, and there was was no recursion (at least not when synchronizing a TreeView and a ListView). By that time it had become a "habit" to use a boolean flag to prevent recursion, and that may have had to do with using a certain third party control.

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  • Tomcat stops responding to JK requests

    - by Bruno Reis
    Hello. I have a nasty issue with load-balanced Tomcat servers that are hanging up. Any help would be greatly appreciated. The system I'm running Tomcat 6.0.26 on HotSpot Server 14.3-b01 (Java 1.6.0_17-b04) on three servers sitting behind another server that acts as load balancer. The load balancer runs Apache (2.2.8-1) + MOD_JK (1.2.25). All of the servers are running Ubuntu 8.04. The Tomcat's have 2 connectors configured: an AJP one, and a HTTP one. The AJP is to be used with the load balancer, while the HTTP is used by the dev team to directly connect to a chosen server (if we have a reason to do so). I have Lambda Probe 1.7b installed on the Tomcat servers to help me diagnose and fix the problem soon to be described. The problem Here's the problem: after about 1 day the application servers are up, JK Status Manager starts reporting status ERR for, say, Tomcat2. It will simply get stuck on this state, and the only fix I've found so far is to ssh the box and restart Tomcat. I must also mention that JK Status Manager takes a lot longer to refresh when there's a Tomcat server in this state. Finally, the "Busy" count of the stuck Tomcat on JK Status Manager is always high, and won't go down per se -- I must restart the Tomcat server, wait, then reset the worker on JK. Analysis Since I have 2 connectors on each Tomcat (AJP and HTTP), I still can connect to the application through the HTTP one. The application works just fine like this, very, very fast. That is perfectly normal, since I'm the only one using this server (as JK stopped delegating requests to this Tomcat). To try to better understand the problem, I've taken a thread dump from a Tomcat which is not responding anymore, and from another one that has been restarted recently (say, 1 hour before). The instance that is responding normally to JK shows most of the TP-ProcessorXXX threads in "Runnable" state, with the following stack trace: java.net.SocketInputStream.socketRead0 ( native code ) java.net.SocketInputStream.read ( SocketInputStream.java:129 ) java.io.BufferedInputStream.fill ( BufferedInputStream.java:218 ) java.io.BufferedInputStream.read1 ( BufferedInputStream.java:258 ) java.io.BufferedInputStream.read ( BufferedInputStream.java:317 ) org.apache.jk.common.ChannelSocket.read ( ChannelSocket.java:621 ) org.apache.jk.common.ChannelSocket.receive ( ChannelSocket.java:559 ) org.apache.jk.common.ChannelSocket.processConnection ( ChannelSocket.java:686 ) org.apache.jk.common.ChannelSocket$SocketConnection.runIt ( ChannelSocket.java:891 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:690 ) java.lang.Thread.run ( Thread.java:619 ) The instance that is stuck show most (all?) of the TP-ProcessorXXX threads in "Waiting" state. These have the following stack trace: java.lang.Object.wait ( native code ) java.lang.Object.wait ( Object.java:485 ) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run ( ThreadPool.java:662 ) java.lang.Thread.run ( Thread.java:619 ) I don't know of the internals of Tomcat, but I would infer that the "Waiting" threads are simply threads sitting on a thread pool. So, if they are threads waiting inside of a thread pool, why wouldn't Tomcat put them to work on processing requests from JK? Solution? So, as I've stated before, the only fix I've found is to stop the Tomcat instance, stop the JK worker, wait the latter's busy count slowly go down, start Tomcat again, and enable the JK worker once again. What is causing this problem? How should I further investigate it? What can I do to solve it? Thanks in advance.

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  • Thread Synchronisation 101

    - by taspeotis
    Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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  • Maven not setting classpath for dependencies properly

    - by Matthew
    OS name: "linux" version: "2.6.32-27-generic" arch: "i386" Family: "unix" Apache Maven 2.2.1 (r801777; 2009-08-06 12:16:01-0700) Java version: 1.6.0_20 I am trying to use the mysql dependency in with maven in ubuntu. If I move the "mysql-connector-java-5.1.14.jar" file that maven downloaded into my $JAVA_HOME/jre/lib/ext/ folder, everything is fine when I run the jar. I think I should be able to just specify the dependency in the pom.xml file and maven should take care of setting the classpath for the dependency jars automatically. Is this incorrect? My pom.xml file looks like this: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.ion.common</groupId> <artifactId>TestPreparation</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <name>TestPrep</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <configuration> <archive> <manifest> <addClasspath>true</addClasspath> <mainClass>com.ion.common.App</mainClass> </manifest> </archive> </configuration> </plugin> </plugins> </build> <dependencies> <!-- JUnit testing dependency --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <!-- MySQL database driver --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.14</version> <scope>compile</scope> </dependency> </dependencies> </project> The command "mvn package" builds it without any problems, and I can run it, but when the application attempts to access the database, this error is presented: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:186) at com.ion.common.Functions.databases(Functions.java:107) at com.ion.common.App.main(App.java:31) The line it is failing on is: Class.forName("com.mysql.jdbc.Driver"); Can anyone tell me what I'm doing wrong or how to fix it?

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  • Broken corba object references

    - by cube
    I'm working on a homework and got stuck. The task is to serve objects using a default servant. But when I try to use the reference, weird things happen. Some part of corba prints a stack trace, but no exception is thrown. The problem happens when the server receives the reference and should call some method on it. The reference is then shortened and doesn't contain the object ID (which means that my servant implementation can't do anything reasonable). This is the implementation of the servant, where the problem appears: public class ModelFileImpl extends ModelFilePOA{ @Override public String getName() { try { return new String(_poa().reference_to_id(_this_object())); } catch (Throwable e) {} assert false; return null; } } If I take _this_object().toString() inside the try block and put it into dior -i i get this: ------IOR components----- TypeId : IDL:termproject/idl/ModelFile:1.0 TAG_INTERNET_IOP Profiles: Profile Id: 0 IIOP Version: 1.2 Host: 127.0.0.1 Port: 45954 Object key (URL): %AF%AB%CB%00%00%00%00%20Q%BA%F4%FF%00%00%00%01%00%00%00%00%00%00%00%01%0000%00%08RootPOA%00%00%00%00%08%00%00%00%02%00%00%00%00%14 Object key (hex): 0xAF AB CB 00 00 00 00 20 51 BA F4 FF 00 00 00 01 00 00 00 00 00 00 00 01 00 00 00 08 52 6F 6F 74 50 4F 41 00 00 00 00 08 00 00 00 02 00 00 00 00 14 -- Found 2 Tagged Components-- #0: TAG_CODE_SETS ForChar native code set Id: ISO8859_1 Char Conversion Code Sets: UTF8 , Unknown TCS: 10020 ForWChar native code set Id: UTF16 WChar Conversion Code Sets: Unknown TCS: 10100 Unknown tag : 38 however the part of server that makes the reference and the client see the reference as ------IOR components----- TypeId : IDL:termproject/idl/ModelFile:1.0 TAG_INTERNET_IOP Profiles: Profile Id: 0 IIOP Version: 1.2 Host: 127.0.0.1 Port: 45954 Object key (URL): %AF%AB%CB%00%00%00%00%20Q%BA%F4%FF%00%00%00%01%00%00%00%00%00%00%00%02%00%00%00%08RootPOA%00%00%00%00%09modelPoa%00%00%00%00%00%00%00%10testModel1.MyIDL%14 Object key (hex): 0xAF AB CB 00 00 00 00 20 51 BA F4 FF 00 00 00 01 00 00 00 00 00 00 00 02 00 00 00 08 52 6F 6F 74 50 4F 41 00 00 00 00 09 6D 6F 64 65 6C 50 6F 61 00 00 00 00 00 00 00 10 74 65 73 74 4D 6F 64 65 6C 31 2E 4D 79 49 44 4C 14 -- Found 2 Tagged Components-- #0: TAG_CODE_SETS ForChar native code set Id: ISO8859_1 Char Conversion Code Sets: UTF8 , Unknown TCS: 10020 ForWChar native code set Id: UTF16 WChar Conversion Code Sets: Unknown TCS: 10100 Unknown tag : 38 ("modelPoa" (the name of the poa working with default clients) and "testModel1.MyIDL" (the identifier of the object) in the object key are missing in the first one) I've tried sniffing the traffic and found out that the client still sends the correct reference. This is how i create the references: ret[i] = ModelFileHelper.narrow(modelFilePoa.create_reference_with_id(files[i].getBytes(), ModelFileHelper.id())); And this is how i set up the server: // init ORB ORB orb = ORB.init(args, null); // init POA POA poa = POAHelper.narrow(orb.resolve_initial_references("RootPOA")); // create the POA for the models. Policy[] policies = { poa.create_request_processing_policy(RequestProcessingPolicyValue.USE_DEFAULT_SERVANT), poa.create_servant_retention_policy(ServantRetentionPolicyValue.NON_RETAIN), poa.create_id_assignment_policy(IdAssignmentPolicyValue.USER_ID) }; POA modelPoa = poa.create_POA("modelPoa", poa.the_POAManager(), policies); modelPoa.the_POAManager().activate(); modelPoa.set_servant(new ModelFileImpl()); modelPoa.the_POAManager().activate(); ModelStoreImpl impl = new ModelStoreImpl(modelPoa); // create the object reference org.omg.CORBA.Object obj = poa.servant_to_reference(impl); // ... store the IOR file ... orb.run(); I'd be really grateful for any pointers (or references :-) )

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  • Why doesn't my QsciLexerCustom subclass work in PyQt4 using QsciScintilla?

    - by Jon Watte
    My end goal is to get Erlang syntax highlighting in QsciScintilla using PyQt4 and Python 2.6. I'm running on Windows 7, but will also need Ubuntu support. PyQt4 is missing the necessary wrapper code for the Erlang lexer/highlighter that "base" scintilla has, so I figured I'd write a lightweight one on top of QsciLexerCustom. It's a little bit problematic, because the Qsci wrapper seems to really want to talk about line+index rather than offset-from-start when getting/setting subranges of text. Meanwhile, the lexer gets arguments as offset-from-start. For now, I get a copy of the entire text, and split that up as appropriate. I have the following lexer, and I apply it with setLexer(). It gets all the appropriate calls when I open a new file and sets this as the lexer, and prints a bunch of appropriate lines based on what it's doing... but there is no styling in the document. I tried making all the defined styles red, and the document is still stubbornly black-on-white, so apparently the styles don't really "take effect" What am I doing wrong? If nobody here knows, what's the appropriate discussion forum where people might actually know these things? (It's an interesting intersection between Python, Qt and Scintilla, so I imagine the set of people who would know is small) Let's assume prefs.declare() just sets up a dict that returns the value for the given key (I've verified this -- it's not the problem). Let's assume scintilla is reasonably properly constructed into its host window QWidget. Specifically, if I apply a bundled lexer (such as QsciLexerPython), it takes effect and does show styled text. prefs.declare('font.name.margin', "MS Dlg") prefs.declare('font.size.margin', 8) prefs.declare('font.name.code', "Courier New") prefs.declare('font.size.code', 10) prefs.declare('color.editline', "#d0e0ff") class LexerErlang(Qsci.QsciLexerCustom): def __init__(self, obj = None): Qsci.QsciLexerCustom.__init__(self, obj) self.sci = None self.plainFont = QtGui.QFont() self.plainFont.setPointSize(int(prefs.get('font.size.code'))) self.plainFont.setFamily(prefs.get('font.name.code')) self.marginFont = QtGui.QFont() self.marginFont.setPointSize(int(prefs.get('font.size.code'))) self.marginFont.setFamily(prefs.get('font.name.margin')) self.boldFont = QtGui.QFont() self.boldFont.setPointSize(int(prefs.get('font.size.code'))) self.boldFont.setFamily(prefs.get('font.name.code')) self.boldFont.setBold(True) self.styles = [ Qsci.QsciStyle(0, QtCore.QString("base"), QtGui.QColor("#000000"), QtGui.QColor("#ffffff"), self.plainFont, True), Qsci.QsciStyle(1, QtCore.QString("comment"), QtGui.QColor("#008000"), QtGui.QColor("#eeffee"), self.marginFont, True), Qsci.QsciStyle(2, QtCore.QString("keyword"), QtGui.QColor("#000080"), QtGui.QColor("#ffffff"), self.boldFont, True), Qsci.QsciStyle(3, QtCore.QString("string"), QtGui.QColor("#800000"), QtGui.QColor("#ffffff"), self.marginFont, True), Qsci.QsciStyle(4, QtCore.QString("atom"), QtGui.QColor("#008080"), QtGui.QColor("#ffffff"), self.plainFont, True), Qsci.QsciStyle(5, QtCore.QString("macro"), QtGui.QColor("#808000"), QtGui.QColor("#ffffff"), self.boldFont, True), Qsci.QsciStyle(6, QtCore.QString("error"), QtGui.QColor("#000000"), QtGui.QColor("#ffd0d0"), self.plainFont, True), ] print("LexerErlang created") def description(self, ix): for i in self.styles: if i.style() == ix: return QtCore.QString(i.description()) return QtCore.QString("") def setEditor(self, sci): self.sci = sci Qsci.QsciLexerCustom.setEditor(self, sci) print("LexerErlang.setEditor()") def styleText(self, start, end): print("LexerErlang.styleText(%d,%d)" % (start, end)) lines = self.getText(start, end) offset = start self.startStyling(offset, 0) print("startStyling()") for i in lines: if i == "": self.setStyling(1, self.styles[0]) print("setStyling(1)") offset += 1 continue if i[0] == '%': self.setStyling(len(i)+1, self.styles[1]) print("setStyling(%)") offset += len(i)+1 continue self.setStyling(len(i)+1, self.styles[0]) print("setStyling(n)") offset += len(i)+1 def getText(self, start, end): data = self.sci.text() print("LexerErlang.getText(): " + str(len(data)) + " chars") return data[start:end].split('\n') Applied to the QsciScintilla widget as follows: _lexers = { 'erl': (Q.SCLEX_ERLANG, LexerErlang), 'hrl': (Q.SCLEX_ERLANG, LexerErlang), 'html': (Q.SCLEX_HTML, Qsci.QsciLexerHTML), 'css': (Q.SCLEX_CSS, Qsci.QsciLexerCSS), 'py': (Q.SCLEX_PYTHON, Qsci.QsciLexerPython), 'php': (Q.SCLEX_PHP, Qsci.QsciLexerHTML), 'inc': (Q.SCLEX_PHP, Qsci.QsciLexerHTML), 'js': (Q.SCLEX_CPP, Qsci.QsciLexerJavaScript), 'cpp': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'h': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'cxx': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'hpp': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'c': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'hxx': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'tpl': (Q.SCLEX_CPP, Qsci.QsciLexerCPP), 'xml': (Q.SCLEX_XML, Qsci.QsciLexerXML), } ... inside my document window class ... def addContentsDocument(self, contents, title): handler = self.makeScintilla() handler.title = title sci = handler.sci sci.append(contents) self.tabWidget.addTab(sci, title) self.tabWidget.setCurrentWidget(sci) self.applyLexer(sci, title) EventBus.bus.broadcast('command.done', {'text': 'Opened ' + title}) return handler def applyLexer(self, sci, title): (language, lexer) = language_and_lexer_from_title(title) if lexer: l = lexer() print("making lexer: " + str(l)) sci.setLexer(l) else: print("setting lexer by id: " + str(language)) sci.SendScintilla(Qsci.QsciScintillaBase.SCI_SETLEXER, language) linst = sci.lexer() print("lexer: " + str(linst)) def makeScintilla(self): sci = Qsci.QsciScintilla() sci.setUtf8(True) sci.setTabIndents(True) sci.setIndentationsUseTabs(False) sci.setIndentationWidth(4) sci.setMarginsFont(self.smallFont) sci.setMarginWidth(0, self.smallFontMetrics.width('00000')) sci.setFont(self.monoFont) sci.setAutoIndent(True) sci.setBraceMatching(Qsci.QsciScintilla.StrictBraceMatch) handler = SciHandler(sci) self.handlers[sci] = handler sci.setMarginLineNumbers(0, True) sci.setCaretLineVisible(True) sci.setCaretLineBackgroundColor(QtGui.QColor(prefs.get('color.editline'))) return handler Let's assume the rest of the application works, too (because it does :-)

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