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• Hibernate Communications Link Failure in Hibernate Based Java Servlet application powered by MySQL

  - by Vatsala

  Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?) edit - Here are the c3p0 parameters I tried out - select 1; 2

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• Impersonation on Windows 2000 to Windows XP Leaves Connections Open

  - by Tallek

  I'm running on a Windows 2000 Pro SP4 box (off domain) and trying to impersonate a local user on a Windows XP box (on domain). I'm using code very similar to the WindowsImpersonationContextFacade in the question posted here: http://stackoverflow.com/questions/879704/how-can-i-temporarily-impersonate-a-user-to-open-a-file. I am using impersonation to remotely start and stop windows services as well as access network shares (for some automated integration tests). To get this working, i had to use LOGON32_PROVIDER_DEFAULT and LOGON32_LOGON_NEW_CREDENTIALS when calling LogonUser. Everything worked beautifully ( Windows XP on domain to Windows XP on domain, Windows XP on domain to Windows Server 2003 off domain, and even Windows XP on domain to Windows 2000 off domain). The one issue was running on Windows 2000 Pro SP4 off the domain and trying to impersonate a local user on a Windows XP box running on the domain. To get the Windows 2000 piece working, i had to use LOGON32_PROVIDER_WINNT50 and LOGON32_LOGON_NEW_CREDENTIALS when calling LogonUser. This seemed to get me 95% of the way there, i could now impersonate the local user on the XP box and start/stop services as well as access a network share using the impersonated credentials. I'm running in to one problem though, calling Undo impersonation and closing the token handle seems to leave the connection to the remote box open. After about 10 or so impersonation calls, further impersonation attempts will fail with an error saying something about too many connections are currently open. If i look at the Computer Management - System Tools - Shared Folders - Sessions on my remote Windows XP box, i can see about 10 sessions open to the Windows 2000 box. I can manually close these (i think they may eventually close themselves, but not very quickly) and then impersonation begins working again few more times. This open session issue doesn't seem to be a problem in any of my other test scenarios, just when running locally on a Windows 2000 box. Any ideas? Edit 1: After some more testing and trying out many different things, this seems to be an issue with open sessions not being reused. On Windows 2000 only, every call to LogonUser to get a token and then using that token to impersonate seems to result in a new session being created. I'm guessing Windows XP & Windows Server 2003 are reusing open sessions since i don't seem to be having any issues with them. If I call LogonUser once, then cache the token, I seem to be able to make as many calls to impersonate as I need using the cached token without running in to the "too many connections" issue. This seems like an ugly work around though since i can't call CloseHandle() on my token every time i perform impersonation. Anybody have any thoughts or ideas, or am i stuck with this ugly hack? Thanks

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• Recommendations for a free GIS library supporting raster images

  - by gspr

  Hi. I'm quite new to the whole field of GIS, and I'm about to make a small program that essentially overlays GPS tracks on a map together with some other annotations. I primarily need to allow scanned (thus raster) maps (although it would be nice to support proper map formats and something like OpenStreetmap in the long run). My first exploratory program uses Qt's graphics view framework and overlays the GPS points by simply projecting them onto the tangent plane to the WGS84 ellipsoid at a calibration point. This gives half-decent accuracy, and actually looks good. But then I started wondering. To get the accuracy I need (i.e. remove the "half" in "half-decent"), I have to correct for the map projection. While the math is not a problem in itself, supporting many map projection feels like needless work. Even though a few projections would probably be enough, I started thinking about just using something like the PROJ.4 library to do my projections. But then, why not take it all the way? Perhaps I might aswell use a full-blown map library such as Mapnik (edit: Quantum GIS also looks very nice), which will probably pay off when I start to want even more fancy annotations or some other symptom of featuritis. So, finally, to the question: What would you do? Would you use a full-blown map library? If so, which one? Again, it's important that it supports using (and zooming in and out with) raster maps and has pretty overlay features. Or would you just keep it simple, and go with Qt's own graphics view framework together with something like PROJ.4 to handle the map projections? I appreciate any feedback! Some technicalities: I'm writing in C++ with a Qt-based GUI, so I'd prefer something that plays relatively nicely with those. Also, the library must be free software (as in FOSS), and at least decently cross-platform (GNU/Linux, Windows and Mac, at least). Edit: OK, it seems I didn't do quite enough research before asking this question. Both Quantum GIS and Mapnik seem very well suited for my purpose. The former especially so since it's based on Qt.

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• symfony/zend integration - blank screen

  - by user142176

  Hi, I need to use ZendAMF on a symfony project and I'm currently working on integrating the two. I have a frontend app with two modules, one of which is 'gateway' - the AMF gateway. In my frontend app config, I have the following in the configure function: // load symfony autoloading first parent::initialize(); // Integrate Zend Framework require_once('[MY PATH TO ZEND]\Loader.php'); spl_autoload_register(array('Zend_Loader', 'autoload')); The executeIndex function my the gateway actions.class.php looks like this // No Layout $this->setLayout(false); // Set MIME Type $this->getResponse()->setContentType('application/x-amf; charset='.sfConfig::get('sf_charset')); // Disable cause this is a non-html page sfConfig::set('sf_web_debug', false); // Create AMF Server $server = new Zend_Amf_Server(); $server->setClass('MYCLASS'); echo $server->handle(); return sfView::NONE; Now when I try to visit the url for the gateway module, or even the other module which was working perfectly fine until this attempt, I only see a blank screen, with not even the symfony dev bar loaded. Oddly enough, my symfony logs are not being updated as well, which suggests that Synfony is not even being 'reached'. So presumably the error has something to do with Zend, but I have no idea how to figure out what the error could be. One thing I do know for sure is that this is not a file path error, because if I change the path in the following line (a part of frontendConfiguration as shown above), I get a Zend_Amf_Server not found error. So the path must be correct. Also if I comment out this very same line, the second module resumes to normality, and my gateway broadcasts a blank x-amf stream. spl_autoload_register(array('Zend_Loader', 'autoload')); Does anyone have any tips on how I could attach this problem? Thanks P.S. I'm currently running an older version of Zend, which is why I am using Zend_Loader instead of Zend_autoLoader (I think). But I've tried switching to the new lib, but the error still remains. So it's not a version problem as well.

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• Django Encoding Issues with MySQL

  - by Jordan Reiter

  Okay, so I have a MySQL database set up. Most of the tables are latin1 and Django handles them fine. But, some of them are UTF-8 and Django does not handle them. Here's a sample table (these tables are all from django-geonames): DROP TABLE IF EXISTS `geoname`; SET @saved_cs_client = @@character_set_client; SET character_set_client = utf8; CREATE TABLE `geoname` ( `id` int(11) NOT NULL, `name` varchar(200) NOT NULL, `ascii_name` varchar(200) NOT NULL, `latitude` decimal(20,17) NOT NULL, `longitude` decimal(20,17) NOT NULL, `point` point default NULL, `fclass` varchar(1) NOT NULL, `fcode` varchar(7) NOT NULL, `country_id` varchar(2) NOT NULL, `cc2` varchar(60) NOT NULL, `admin1_id` int(11) default NULL, `admin2_id` int(11) default NULL, `admin3_id` int(11) default NULL, `admin4_id` int(11) default NULL, `population` int(11) NOT NULL, `elevation` int(11) NOT NULL, `gtopo30` int(11) NOT NULL, `timezone_id` int(11) default NULL, `moddate` date NOT NULL, PRIMARY KEY (`id`), KEY `country_id_refs_iso_alpha2_e2614807` (`country_id`), KEY `admin1_id_refs_id_a28cd057` (`admin1_id`), KEY `admin2_id_refs_id_4f9a0f7e` (`admin2_id`), KEY `admin3_id_refs_id_f8a5e181` (`admin3_id`), KEY `admin4_id_refs_id_9cc00ec8` (`admin4_id`), KEY `fcode_refs_code_977fe2ec` (`fcode`), KEY `timezone_id_refs_id_5b46c585` (`timezone_id`), KEY `geoname_52094d6e` (`name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; SET character_set_client = @saved_cs_client; Now, if I try to get data from the table directly using MySQLdb and a cursor, I get the text with the proper encoding: >>> import MySQLdb >>> from django.conf import settings >>> >>> conn = MySQLdb.connect (host = "localhost", ... user = settings.DATABASES['default']['USER'], ... passwd = settings.DATABASES['default']['PASSWORD'], ... db = settings.DATABASES['default']['NAME']) >>> cursor = conn.cursor () >>> cursor.execute("select name from geoname where name like 'Uni%Hidalgo'"); 1L >>> g = cursor.fetchone() >>> g[0] 'Uni\xc3\xb3n Hidalgo' >>> print g[0] Unión Hidalgo However, if I try to use the Geoname model (which is actually a django.contrib.gis.db.models.Model), it fails: >>> from geonames.models import Geoname >>> g = Geoname.objects.get(name__istartswith='Uni',name__icontains='Hidalgo') >>> g.name u'Uni\xc3\xb3n Hidalgo' >>> print g.name Unión Hidalgo There's pretty clearly an encoding error here. In both cases the database is returning 'Uni\xc3\xb3n Hidalgo' but Django is (incorrectly?) translating the '\xc3\xb3n' to ó. What can I do to fix this?

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• Choosing a distributed shared memory solution

  - by mindas

  I have a task to build a prototype for a massively scalable distributed shared memory (DSM) app. The prototype would only serve as a proof-of-concept, but I want to spend my time most effectively by picking the components which would be used in the real solution later on. The aim of this solution is to take data input from an external source, churn it and make the result available for a number of frontends. Those "frontends" would just take the data from the cache and serve it without extra processing. The amount of frontend hits on this data can literally be millions per second. The data itself is very volatile; it can (and does) change quite rapidly. However the frontends should see "old" data until the newest has been processed and cached. The processing and writing is done by a single (redundant) node while other nodes only read the data. In other words: no read-through behaviour. I was looking into solutions like memcached however this particular one doesn't fulfil all our requirements which are listed below: The solution must at least have Java client API which is reasonably well maintained as the rest of app is written in Java and we are seasoned Java developers; The solution must be totally elastic: it should be possible to add new nodes without restarting other nodes in the cluster; The solution must be able to handle failover. Yes, I realize this means some overhead, but the overall served data size isn't big (1G max) so this shouldn't be a problem. By "failover" I mean seamless execution without hardcoding/changing server IP address(es) like in memcached clients when a node goes down; Ideally it should be possible to specify the degree of data overlapping (e.g. how many copies of the same data should be stored in the DSM cluster); There is no need to permanently store all the data but there might be a need of post-processing of some of the data (e.g. serialization to the DB). Price. Obviously we prefer free/open source but we're happy to pay a reasonable amount if a solution is worth it. In any way, paid 24hr/day support contract is a must. The whole thing has to be hosted in our data centers so SaaS offerings like Amazon SimpleDB are out of scope. We would only consider this if no other options would be available. Ideally the solution would be strictly consistent (as in CAP); however, eventual consistence can be considered as an option. Thanks in advance for any ideas.

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• MySQL Connection error in spring MVC

  - by nidhi

  i am working on spring MVC facing the following exception while connecting to my sql. Blocorg.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.) at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80) at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:572) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:636) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:665) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:673) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:728) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:744) at org.springframework.jdbc.core.JdbcTemplate.queryForInt(JdbcTemplate.java:775) at com.trackmeetings.dao.InboxDAOImpl.getNotificationsCount(InboxDAOImpl.java:51) at com.trackmeetings.service.InboxService.getNotificationsCount(InboxService.java:56) at com.trackmeetings.controller.HomePageController.getLogInUserDetails(HomePageController.java:80) 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.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:175) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:421) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:409) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:774) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560) at javax.servlet.http.HttpServlet.service(HttpServlet.java:710) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.trackmeetings.util.NoCacheFilter.doFilter(NoCacheFilter.java:56) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) 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:175) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:680) Caused by: org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.) at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1225) at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880) at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111) at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77) ... 38 more Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failurekquote how can i resolve this. please help,

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• Validating against a Schema with JAXB

  - by fwgx

  I've been looking for solutions to this problem for far too long considering how easy it sounds so I've come for some help. I have an XML Schema which I have used with xjc to create my JAXB binding. This works fine when the XML is well formed. Unfortunately it also doesn't complain when the XML is not well formed. I cannot figure out how to do proper full validation against the schema when I try to unmarshall an XML file. I have managed to use a ValidationEventCollector to handle events, which works for XML parsing errors such as mismatched tags but doesn't raise any events when there is a tag that is required but is completely absent. From what I have seen validation can be done againsta schema, but you must know the path to the schema in order to pass it into the setSchema() method. The problem I have is that the path to the schema is stored in the XML header and I can't knwo at run time where the schema is going to be. Which is why it's stored in the XML file: <?xml version="1.0" encoding="utf-8"?> <DDSSettings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="/a/big/long/path/to/a/schema/file/DDSSettings.xsd"> <Field1>1</Field1> <Field2>-1</Field2> ...etc Every example I see uses setValidating(true), which is now deprecated, so throws an exception. This is the Java code I have so far, which seems to only do XML validation, not schema validation: try { JAXBContext jc = new JAXBContext() { private final JAXBContext jaxbContext = JAXBContext.newInstance("blah"); @Override public Unmarshaller createUnmarshaller() throws JAXBException { Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); ValidationEventCollector vec = new ValidationEventCollector() { @Override public boolean handleEvent(ValidationEvent event) throws RuntimeException { ValidationEventLocator vel = event.getLocator(); if (event.getSeverity() == event.ERROR || event.getSeverity() == event.FATAL_ERROR) { String error = "XML Validation Exception: " + event.getMessage() + " at row: " + vel.getLineNumber() + " column: " + vel.getColumnNumber(); System.out.println(error); } m_unmarshallingOk = false; return false; } }; unmarshaller.setEventHandler(vec); return unmarshaller; } @Override public Marshaller createMarshaller() throws JAXBException { throw new UnsupportedOperationException("Not supported yet."); } @Override @SuppressWarnings("deprecation") public Validator createValidator() throws JAXBException { throw new UnsupportedOperationException("Not supported yet."); } }; Unmarshaller unmarshaller = jc.createUnmarshaller(); m_ddsSettings = (com.ultra.DDSSettings)unmarshaller.unmarshal(new File(xmlfileName)); } catch (UnmarshalException ex) { Logger.getLogger(UniversalDomainParticipant.class.getName()).log( Level.SEVERE, null, ex); } catch (JAXBException ex) { Logger.getLogger(UniversalDomainParticipant.class.getName()).log( Level.SEVERE, null, ex); } So what is the proper way to do this validation? I was expecting there to be a validate() method on the JAXB generated classes, but I guess that would be too simple for Java.

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• Container item implementation

  - by onurozcelik

  Hi, I am working in Train Traffic Controller software project. My responsibility in this project is to develop the visual railroad GUI. We are implementing the project with Qt. By now I am using QGraphicsLinearLayout to hold my items. I am using the layout because I do not want to calculate coordinates of each item. So far I wrote item classes to add the layout. For instance SwitchItem class symbolizes railroad switch in real world. Each item class is responsible for its own painting and events. So far so good. Now I need a composite item that can contain two or more item. This class is going to be responsible for painting the items contained in it. I need this class because I have to put two or more items inside same layout cell. If I don' t put them in same cell I can' t use layout. See the image below. BlockSegmentItem and SignalItem inside same cell. Here is my compositeitem implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { FieldItem *child; QRectF rect(0,0,0,0); foreach(child,children) { rect = rect.united(child->boundingRect()); } return rect; } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } This code works good with painting but when it comes to item events it is problematic. QGraphicsScene treats the composite item like a single item which is right for layout but not for events. Because each item has its own event implementation.(e.g. SignalItem has its special context menu event.) I have to handle item events seperately. Also I need a composite item implementation for the layout. How can I overcome this dilemma?

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• How can I make the C# compiler infer these type parameters automatically?

  - by John Feminella

  I have some code that looks like the following. First I have some domain classes and some special comparators for them. public class Fruit { public int Calories { get; set; } public string Name { get; set; } } public class FruitEqualityComparer : IEqualityComparer<Fruit> { // ... } public class BasketEqualityComparer : IEqualityComparer<IEnumerable<Fruit>> { // ... } Next, I have a helper class called ConstraintChecker. It has a simple BaseEquals method that makes sure some simple base cases are considered: public static class ConstraintChecker { public static bool BaseEquals(T lhs, T rhs) { bool sameObject = l == r; bool leftNull = l == null; bool rightNull = r == null; return sameObject && !leftNull && !rightNull; } There's also a SemanticEquals method which is just a BaseEquals check and a comparator function that you specify. public static bool SemanticEquals<T>(T lhs, T rhs, Func<T, T, bool> f) { return BaseEquals(lhs, rhs) && f(lhs, rhs); } And finally there's a SemanticSequenceEquals method which accepts two IEnumerable<T> instances to compare, and an IEqualityComparer instance that will get called on each pair of elements in the list via Enumerable.SequenceEquals. public static bool SemanticSequenceEquals<T, U, V>(U lhs, U rhs, V comparator) where U : IEnumerable<T> where V : IEqualityComparer<T> { return SemanticEquals(lhs, rhs, (l, r) => lhs.SequenceEqual(rhs, comparator)); } } // end of ConstraintChecker The point of SemanticSequenceEquals is that you don't have to define two comparators whenever you want to compare both IEnumerable<T> and T instances; now you can just specify an IEqualityComparer<T> and it will also handle lists when you invoke SemanticSequenceEquals. So I could get rid of the BasketEqualityComparer class, which would be nice. But there's a problem. The C# compiler can't figure out the types involved when you invoke SemanticSequenceEquals: return ConstraintChecker.SemanticSequenceEquals(lhs, rhs, new FruitEqualityComparer()); If I specify them explicitly, it works: return ConstraintChecker.SemanticSequenceEquals< Fruit, IEnumerable<Fruit>, IEqualityComparer<Fruit> > (lhs, rhs, new FruitEqualityComparer()); What can I change here so that I don't have to write the type parameters explicitly?

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• find window text and save txt to file named that wont work.

  - by blood

  hi, my code wont work and idk why. the point of my code is to find the top window and save a text file with the name the same as the text on the top menu bar (task bar i think?). then save some data to that text file. but everytime i try to use it the write fails if i set the name of the text file before hand so it wont change it will write the data to the file. but if i don't set it before hand it will make the text doc but not write anything to it. or sometimes it will just write numbers for the name (i think it's the handle number) then it will write the data. :\ it's odd can anyone help? #include <iostream> #include <windows.h> #include <fstream> #include <string> #include <sstream> #include <time.h> using namespace std; string header_str = ("NULL"); #define DTTMFMT "%Y-%m-%d %H:%M:%S " #define DTTMSZ 21 char buff[DTTMSZ]; fstream filestr; string ff = ("C:\\System logs\\txst.txt"); TCHAR buf[255]; int main() { GetWindowText(GetForegroundWindow(), buf, 255); stringstream header(stringstream::in | stringstream::out); header.flush(); header << ("C:\\System logs\\"); header << buf; header << (".txt"); header_str = header.str(); ff = header_str; cout << header_str << "\n"; filestr.open (ff.c_str(), fstream::in | fstream::out | fstream::app | ios_base::binary | ios_base::out); filestr << "dfg"; filestr.close(); Sleep(10000); return 0; }

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• Unmanaged Code calling leads to heavy memory leak!!

  - by konnychen

  Maybe I need change the title as "Unmanaged Code calling leads to heavy memory leak!" The leak is around 30M/hour I think maybe I need complete my code here because the memory leak maybe not from a static string whereas my real code derive this string from external device (see new code attached). so I handle also unmanaged code. Could it be possible the leak comes from unmanaged code? But I freed the resouce by Marshal.FreeCoTaskMem(pos); oThread2 = new Thread(new ThreadStart(Cyclic_Call)); oThread2.Start(); delegate void SetText_lab_Statubar(string text); private void m_SetText_lab_Statubar(string text) { if (this.lab_Statubar.InvokeRequired) { SetText_lab_Statubar d = new SetText_lab_Statubar(m_SetText_lab_Statubar); this.Invoke(d, new object[] { text }); } else { this.lab_Statubar.Text = text; } } private void Cyclic_Call() { do { //... ... ReadMatrixCode(Station6, 0, str_Code); this.m_SetText_lab_Statubar(str_Code[4]); Thread.Sleep(100); } while (!b_AbortThraed); } private void ReadMatrixCode(Station st, int ItemNr, string[] str_Code) { IntPtr pItemStates = IntPtr.Zero; IntPtr pErrors = IntPtr.Zero; int NumItems = itemServerHandles.Length; m_SyncIO.Read(DataSrc, NumItems, itemServerHandles, out pItemStates, out pErrors); // This calls external dll which has some of "out IntPtr" errors = new int[NumItems]; Marshal.Copy(pErrors, errors, 0, NumItems); IntPtr pos = pItemStates; // Now get the read values and check errors for (int dwCount = 0; dwCount < NumItems; dwCount++) { result[dwCount] = (ITEMSTATE)Marshal.PtrToStructure(pos, typeof(ITEMSTATE)); pos = (IntPtr)(pos.ToInt32() + Marshal.SizeOf(typeof(ITEMSTATE))); } // Free allocated COM-ressouces Marshal.FreeCoTaskMem(pItemStates); Marshal.FreeCoTaskMem(pErrors); pItemStates = IntPtr.Zero; pErrors = IntPtr.Zero; } m_syncIO is a class and finally it will call COM component which is defined below [Guid("39C12B52-011E-11D0-9675-1020AFD8ADB3")] [InterfaceType(1)] [ComConversionLoss] public interface ISyncIO { void Read(DATASOURCE dwSource, int dwCount, int[] phServer, out IntPtr ppItemValues, out IntPtr ppErrors); void Write(int dwCount, int[] phServer, object[] pItemValues, out IntPtr ppErrors); }

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• Count total children divs inside a container

  - by kuswantin

  I want to count the total divs inside a container and toggle their visibilities with structure like this. Please also note that the div.content may also reside inside another nested or even nested-nested containers. That's why I handle it with jquery to add div.topmost for each topmost parent container: <div id="parent"> <div class="counter">There are 3 div.contents inside the container below</div> <div class="container"> <div class="content"> 1 </div> <div class="container"> <!--container inside container --> <div class="content"> 2 </div> <div class="content"> 3 </div> </div> </div> <div class="counter">There are 5 div.contents inside the container below</div> <div class="container"> <div class="content"> 1 </div> <div class="content"> 2 </div> <div class="content"> 3 </div> <div class="content"> 4 </div> <div class="content"> 5 </div> </div> </div> And the jquery: // only grab the top most container $('#parent > .container').addClass('topmost'); var topMost = $(".topmost"); var totContent = topMost.children('.content').size(); if (topMost.length > 0) { topMost.before('<div class="toggle">There are ' + totContent + ' div.contents inside the container below</div>'); } topMost.hide(); $('#parent > .counter').click(function() { $(this).next('.topmost').toggle(); //alert(totContent); return false; }); But I can't make it work to loop for each div.counter. The counter always shows all div.content. So placing the each function is suspected to be the problem. Any hep would be very much appreciated. Thanks

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• Custom Tag implementation issue

  - by Appps

  I have a custom tag as follows. repeat and heading tag have doAfterBody method implemented. <csajsp:repeat reps="5"> <LI> <csajsp:heading bgColor="BLACK"> White on Black Heading </csajsp:heading> </LI> </csajsp:repeat> /* Repeat tag Class*/ public void setReps(String repeats) { System.out.println("TESTING"+repeats); //sets the reps variable. } public int doAfterBody() { System.out.println("Inside repeate tag"+reps); if (reps-- >= 1) { BodyContent body = getBodyContent(); try { JspWriter out = body.getEnclosingWriter(); System.out.println("BODY"+body.getString()); out.println(body.getString()); body.clearBody(); // Clear for next evaluation } catch(IOException ioe) { System.out.println("Error in RepeatTag: " + ioe); } return(EVAL_BODY_TAG); } else { return(SKIP_BODY); } } /* Class of Heading tag */ public int doAfterBody() { System.out.println("inside heading tag"); BodyContent body = getBodyContent(); System.out.println(body.getString()); try { JspWriter out = body.getEnclosingWriter(); out.print("NEW TEXT"); } catch(IOException ioe) { System.out.println("Error in FilterTag: " + ioe); } // SKIP_BODY means I'm done. If I wanted to evaluate // and handle the body again, I'd return EVAL_BODY_TAG. return(SKIP_BODY); } public int doEndTag() { try { JspWriter out = pageContext.getOut(); out.print("NEW TEXT 2"); } catch(IOException ioe) { System.out.println("Error in HeadingTag: " + ioe); } return(EVAL_PAGE); // Continue with rest of JSP page } The order in which SOP are printed is 1) Setter method of csajsp:repeat is called. 2) White on Black Heading is printed. ie doAfterBody of csajsp:heading tag is called. I don't know why it is not calling doAfterBody of csajsp:repeat tag. Please help me to understand this. Thanks in advance.

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• Escaping Code for Different Shells

  - by Jon Purdy

  Question: What characters do I need to escape in a user-entered string to securely pass it into shells on Windows and Unix? What shell differences and version differences should be taken into account? Can I use printf "%q" somehow, and is that reliable across shells? Backstory (a.k.a. Shameless Self-Promotion): I made a little DSL, the Vision Web Template Language, which allows the user to create templates for X(HT)ML documents and fragments, then automatically fill them in with content. It's designed to separate template logic from dynamic content generation, in the same way that CSS is used to separate markup from presentation. In order to generate dynamic content, a Vision script must defer to a program written in a language that can handle the generation logic, such as Perl or Python. (Aside: using PHP is also possible, but Vision is intended to solve some of the very problems that PHP perpetuates.) In order to do this, the script makes use of the @system directive, which executes a shell command and expands to its output. (Platform-specific generation can be handled using @unix or @windows, which only expand on the proper platform.) The problem is obvious, I should think: test.htm: <!-- ... --> <form action="login.vis" method="POST"> <input type="text" name="USERNAME"/> <input type="password" name="PASSWORD"/> </form> <!-- ... --> login.vis: #!/usr/bin/vision # Think USERNAME = ";rm -f;" @system './login.pl' { USERNAME; PASSWORD } One way to safeguard against this kind of attack is to set proper permissions on scripts and directories, but Web developers may not always set things up correctly, and the naive developer should get just as much security as the experienced one. The solution, logically, is to include a @quote directive that produces a properly escaped string for the current platform. @system './login.pl' { @quote : USERNAME; @quote : PASSWORD } But what should @quote actually do? It needs to be both cross-platform and secure, and I don't want to create terrible problems with a naive implementation. Any thoughts?

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• Why doesn't my form post when I disable the submit button to prevent double clicking?

  - by John MacIntyre

  Like every other web developer on the planet, I have an issue with users double clicking the submit button on my forms. My understanding is that the conventional way to handle this issue, is to disable the button immediately after the first click, however when I do this, it doesn't post. I did do some research on this, god knows there's enough information, but other questions like Disable button on form submission, disabling the button appears to work. The original poster of Disable button after submit appears to have had the same problem as me, but there is no mention on how/if he resolved it. Here's some code on how to repeat it (tested in IE8 Beta2, but had same problem in IE7) My aspx code <%@ Page Language="C#" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <script language="javascript" type="text/javascript"> function btn_onClick() { var chk = document.getElementById("chk"); if(chk.checked) { var btn = document.getElementById("btn"); btn.disabled = true; } } </script> <body> <form id="form1" runat="server"> <asp:Literal ID="lit" Text="--:--:--" runat="server" /> <br /> <asp:Button ID="btn" Text="Submit" runat="server" /> <br /> <input type="checkbox" id="chk" />Disable button on first click </form> </body> </html> My cs code using System; public partial class _Default : System.Web.UI.Page { protected override void OnInit(EventArgs e) { base.OnInit(e); btn.Click += new EventHandler(btn_Click); btn.OnClientClick = "btn_onClick();"; } void btn_Click(object sender, EventArgs e) { lit.Text = DateTime.Now.ToString("HH:mm:ss"); } } Notice that when you click the button, a postback occurs, and the time is updated. But when you check the check box, the next time you click the button, the button is disabled (as expected), but never does the postback. WHAT THE HECK AM I MISSING HERE??? Thanks in advance.

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• iPhone: Problems releasing UIViewController in a multithreaded environment

  - by bart-simpson

  Hi! I have a UIViewController and in that controller, i am fetching an image from a URL source. The image is fetched in a separate thread after which the user-interface is updated on the main thread. This controller is displayed as a page in a UIScrollView parent which is implemented to release controllers that are not in view anymore. When the thread finishes fetching content before the UIViewController is released, everything works fine - but when the user scrolls to another page before the thread finishes, the controller is released and the only handle to the controller is owned by the thread making releaseCount of the controller equals to 1. Now, as soon as the thread drains NSAutoreleasePool, the controller gets releases because the releaseCount becomes 0. At this point, my application crashes and i get the following error message: bool _WebTryThreadLock(bool), 0x4d99c60: Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now... The backtrace reveals that the application crashed on the call to [super dealloc] and it makes total sense because the dealloc function must have been triggered by the thread when the pool was drained. My question is, how i can overcome this error and release the controller without leaking memory? One solution that i tried was to call [self retain] before the pool is drained so that retainCount doesn't fall to zero and then using the following code to release controller in the main thread: [self performSelectorOnMainThread:@selector(autorelease) withObject:nil waitUntilDone:NO]; Unfortunately, this did not work out. Below is the function that is executed on a thread: - (void)thread_fetchContent { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSURL *imgURL = [NSURL URLWithString:@"http://www.domain.com/image.png"]; // UIImage *imgHotspot is declared as private - The image is retained // here and released as soon as it is assigned to UIImageView imgHotspot = [[[UIImage alloc] initWithData: [NSData dataWithContentsOfURL: imgURL]] retain]; if ([self retainCount] == 1) { [self retain]; // increment retain count ~ workaround [pool drain]; // drain pool // this doesn't work - i get the same error [self performSelectorOnMainThread:@selector(autorelease) withObject:nil waitUntilDone:NO]; } else { // show fetched image on the main thread - this works fine! [self performSelectorOnMainThread:@selector(showImage) withObject:nil waitUntilDone:NO]; [pool drain]; } } Please help! Thank you in advance.

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• Python: Script works, but seems to deadlock after some time

  - by sberry2A

  I have the following script, which is working for the most part Link to PasteBin The script's job is to start a number of threads which in turn each start a subprocess with Popen. The output from each subprocess is as follows: 1 2 3 . . . n Done Bascially the subprocess is transferring 10M records from tables in one database to different tables in another db with a lot of data massaging/manipulation in between because of the different schemas. If the subprocess fails at any time in it's execution (bad records, duplicate primary keys, etc), or it completes successfully, it will output "Done\n". If there are no more records to select against for transfer then it will output "NO DATA\n" My intent was to create my script "tableTransfer.py" which would spawn a number of these processes, read their output, and in turn output information such as number of updates completed, time remaining, time elapsed, and number of transfers per second. I started running the process last night and checked in this morning to see it had deadlocked. There were not subprocceses running, there are still records to be updated, and the script had not exited. It was simply sitting there, no longer outputting the current information because no subprocces were running to update the total number complete which is what controls updates to the output. This is running on OS X. I am looking for three things: I would like to get rid of the possibility of this deadlock occurring so I don't need to check in on it as frequently. Is there some issue with locking? Am I doing this in a bad way (gThreading variable to control looping of spawning additional thread... etc.) I would appreciate some suggestions for improving my overall methodology. How should I handle ctrl-c exit? Right now I need to kill the process, but assume I should be able to use the signal module or other to catch the signal and kill the threads, is that right? I am not sure whether I should be pasting my entire script here, since I usually just paste snippets. Let me know if I should paste it here as well.

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• why custom state won't work with compound drawable?

  - by schwiz

  Hello I am trying to make a password registration widget that will show a little checkbox in the textbox when both password boxes match. I decided to go about this by extending EditText to implement a valid and an empty state and then just use a state-list drawable to handle everything else. I followed the same method that the CompoundButton uses to add a custom state and everything seems to be right but the image will never change no matter what the state is (custom state or even state_focused etc) Is there some reason that the compound drawables of a TextView wouldn't work as a state-list drawable? Or, am I doing something wrong? Here is attrs.xml <resources> <declare-styleable name="ValidyState"> <attr name="state_valid" format="boolean"/> <attr name="state_has_text" format="boolean"/> </declare-styleable> </resources> my selector <selector xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res/com.schwiz.test"> <item android:drawable="@drawable/emptyspace" app:state_has_text="false"/> <item android:drawable="@drawable/ic_valid" app:state_valid="true" app:state_has_text="true"/> <item android:drawable="@drawable/ic_invalid" app:state_valid="false" app:state_has_text="true"/> </selector> and in my overridden EditText class private static final int[] VALID_STATE_SET = { R.attr.state_valid }; private static final int[] HASTEXT_STATE_SET = { R.attr.state_has_text }; ... private void refreshDrawables(){ Drawable[] drawables = getCompoundDrawables(); for(int i = 0; i < drawables.length; i++){ if(drawables[i] != null) { drawables[i].setState(getDrawableState()); } } invalidate(); } @Override protected void drawableStateChanged() { super.drawableStateChanged(); refreshDrawables(); } @Override protected int[] onCreateDrawableState(int extraSpace) { final int[] drawableState = super.onCreateDrawableState(extraSpace + 2); if(hasText){ mergeDrawableStates(drawableState, HASTEXT_STATE_SET); } if(isValid){ mergeDrawableStates(drawableState, VALID_STATE_SET); } return drawableState; }

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• What is your most productive shortcut with Vim?

  - by Olivier Pons

  I've heard a lot about Vim, both pros and cons. It really seems you should be (as a developer) faster with Vim than with any other editor. I'm using Vim to do some basic stuff and I'm at best 10 times less productive with Vim. The only two things you should care about when you talk about speed (you may not care enough about them, but you should) are: Using alternatively left and right hands is the fastest way to use the keyboard. Never touching the mouse is the second way to be as fast as possible. It takes ages for you to move your hand, grab the mouse, move it, and bring it back to the keyboard (and you often have to look at the keyboard to be sure you returned your hand properly to the right place) Here are two examples demonstrating why I'm far less productive with Vim. Copy/Cut & paste. I do it all the time. With all the classical editors you press Shift with the left hand, and you move the cursor with your right hand to select text. Then Ctrl+C copies, you move the cursor and Ctrl+V pastes. With Vim it's horrible: yy to copy one line (you almost never want the whole line!) [number xx]yy to copy xx lines into the buffer. But you never know exactly if you've selected what you wanted. I often have to do [number xx]dd then u to undo! Another example? Search & replace. In PSPad: Ctrl+f then type what you want you search for, then press Enter. In Vim: /, then type what you want to search for, then if there are some special characters put \ before each special character, then press Enter. And everything with Vim is like that: it seems I don't know how to handle it the right way. NB : I've already read the Vim cheat sheet :) My question is: What is the way you use Vim that makes you more productive than with a classical editor?

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• Overloading framework methods in objective-c, or retaining local changes with framework updates.

  - by Jeff B

  I am using cocos2d to build an iPhone game. It's mostly done, but along the way I came across some things that I would like to handle better. I am fairly new to Objective C, and honestly I do more Perl scripting in my day-to-day job than anything, so my C skills are a little rusty. One of them is the fact that I have modified cocos2d files for some specific cases in my game. However, when I update to a new version, I have to manually pull my changes forward. So, the question is, what is the best way to deal with this? Some options I have thought of: Overload/redefine the cocos2d classes. I was under the impression that I cannot overload existing class functions, so I don't think this will work. Create patches that I re-apply after library updates. I don't think this will work as the new files won't necessarily be the same as the old ones, and if they were, I could just copy the whole file forward. Turn in my changes to Cocos2d. Not an option as my changes are very specific to my application. Am I missing something obvious? UPDATE: I will explain what I am doing to be more clear. Cocos2d has a CCNode object, which can contain children, etc. I added a shadow, which is very similar to a child, but handled a little differently. The shadow has an offset from the parent, and translates with it's parent, rotates around it's own center when the parent rotates, etc. The shadow is not included as a true child, however, so given the correct z-index, the shadows can render under ALL other objects, but still move with the parent. To do this I added addShadow functions to CCNode, and modified the setPosition and setRotate functions to move the shadowSprite: CCNode.m: -(id) init { if ((self=[super init]) ) { ... shadowSprite_ = nil; ... } } ... -(BOOL) addShadow: (CCNode*) child offset: (CGPoint) offset { shadowSprite_ = child; shadowSprite_.position = CGPointMake(position_.x+offset.x, position_.y+offset.y); return YES; } ... -(void) setRotation: (float)newRotation { rotation_ = newRotation; isTransformDirty_ = isInverseDirty_ = YES; if(shadowSprite_) { [shadowSprite_ setRotation: newRotation]; } } There is more, of course, including the prototypes in the .h file, but that is the basics. I don't think I need shadowSprite to be a property, because I don't need to access it after it has been added.

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• bundler/capistrano is not installing gems with correct ruby version

  - by Douglas

  I'm trying to deploy my first app on a server with Capistrano, and I'm a bit lost with managing gemsets and ruby version. These are my (server and workstation) versions : Rails 3.2.8 RVM 1.16.17 Gem 1.8.24 Bundler 1.2.1 pg gem 0.14.1 My gemset are : Gemsets for ruby-1.9.3-p194 (found in /usr/local/rvm/gems/ruby-1.9.3-p194) (default) global = rail3dev20120606 I set the default gemset with : rvm use 1.9.3-p194@rail3dev20120606 --default --passenger When I run a : cap bundle:install The task end with success, but when I do a : gem list There are many missing gems though they are present in my Gemfile. When I go to check my gems in /var/www/opf/shared/bundle/ruby/ I find a folder called 1.9.1 and in /var/www/opf/shared/bundle/ruby/1.9.1/gems/ I can fond all of my needed gems (specified in Gemfile). I'm sure there is a problem with ruby version, but how do I solve this ? At the moment, if I do any rake command, I got a ruby crash [Bug] Segmentation fault, as it try to access the db and using postgresql_adapter. I think as many gems are missing there must have some gem dependencies not verified, and maybe a gem is using an incompatible ruby version 1.9.1 though it expect a 1.9.3. I think the issue is around managing ruby versions and gems. I'm certainly doing some mix with gemset and my capistrano deployement. I'm missing experience and info. Could anybody advise me how to handle this on the server ? What are the best practices ? How am I suppose to update my ruby version ? with Capistrano deploy.rb ? manually ? with/without rvm ? I saw a new version of ruby 1.9.3-p327 has just released. Should I use gemset or not ? What about the :rvm_ruby_string in my deploy.rb. Is it correctly spelled or should I remove the p194 part ? Should I Remove the :rvm_ruby_string ? Keep it ? Use a .rvmrc file ??? I'm really lost and some kind help would be welcome. This is my config/deploy.rb in any case : require 'bundler/capistrano' require File.join(File.dirname(__FILE__), 'deploy') + '/capistrano_database' set :rvm_type, :system set :rvm_ruby_string, 'ruby-1.9.3-p194@rail3dev20120606' require 'rvm/capistrano' set :application, 'opf' set :deploy_to, '/var/www/opf' set :rails_env, 'production' set :user, 'the_user' set :use_sudo, false set :group_writable, false set :scm, :git set :repository, '[email protected]:user/opf.git' set :branch, 'master' default_run_options[:pty] = true set :deploy_via, :remote_cache server '192.168.5.200', :web, :app, :db, :primary => true # If you are using Passenger mod_rails uncomment this: namespace :deploy do task :start do ; end task :stop do ; end task :restart, :roles => :app, :except => { :no_release => true } do run "#{try_sudo} touch #{File.join(current_path,'tmp','restart.txt')}" end end Thanks for any help

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• Performance tuning of a Hibernate+Spring+MySQL project operation that stores images uploaded by user

  - by Umar

  Hi I am working on a web project that is Spring+Hibernate+MySQL based. I am stuck at a point where I have to store images uploaded by a user into the database. Although I have written some code that works well for now, but I believe that things will mess up when the project would go live. Here's my domain class that carries the image bytes: @Entity public class Picture implements java.io.Serializable{ long id; byte[] data; ... // getters and setters } And here's my controller that saves the file on submit: public class PictureUploadFormController extends AbstractBaseFormController{ ... protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object command, BindException errors) throws Exception{ MutlipartFile file; // getting MultipartFile from the command object ... // beginning hibernate transaction ... Picture p=new Picture(); p.setData(file.getBytes()); pictureDAO.makePersistent(p); // this method simply calls getSession().saveOrUpdate(p) // committing hiernate transaction ... } ... } Obviously a bad piece of code. Is there anyway I could use InputStream or Blob to save the data, instead of first loading all the bytes from the user into the memory and then pushing them into the database? I did some research on hibernate's support for Blob, and found this in Hibernate In Action book: java.sql.Blob and java.sql.Clob are the most efficient way to handle large objects in Java. Unfortunately, an instance of Blob or Clob is only useable until the JDBC transaction completes. So if your persistent class defines a property of java.sql.Clob or java.sql.Blob (not a good idea anyway), you’ll be restricted in how instances of the class may be used. In particular, you won’t be able to use instances of that class as detached objects. Furthermore, many JDBC drivers don’t feature working support for java.sql.Blob and java.sql.Clob. Therefore, it makes more sense to map large objects using the binary or text mapping type, assuming retrieval of the entire large object into memory isn’t a performance killer. Note you can find up-to-date design patterns and tips for large object usage on the Hibernate website, with tricks for particular platforms. Now apparently the Blob cannot be used, as it is not a good idea anyway, what else could be used to improve the performance? I couldn't find any up-to-date design pattern or any useful information on Hibernate website. So any help/recommendations from stackoverflowers will be much appreciated. Thanks

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• What's a clean way to break up a DataTable into chunks of a fixed size with Linq?

  - by Michael Haren

  Update: Here's a similar question Suppose I have a DataTable with a few thousand DataRows in it. I'd like to break up the table into chunks of smaller rows for processing. I thought C#3's improved ability to work with data might help. This is the skeleton I have so far: DataTable Table = GetTonsOfData(); // Chunks should be any IEnumerable<Chunk> type var Chunks = ChunkifyTableIntoSmallerChunksSomehow; // ** help here! ** foreach(var Chunk in Chunks) { // Chunk should be any IEnumerable<DataRow> type ProcessChunk(Chunk); } Any suggestions on what should replace ChunkifyTableIntoSmallerChunksSomehow? I'm really interested in how someone would do this with access C#3 tools. If attempting to apply these tools is inappropriate, please explain! Update 3 (revised chunking as I really want tables, not ienumerables; going with an extension method--thanks Jacob): Final implementation: Extension method to handle the chunking: public static class HarenExtensions { public static IEnumerable<DataTable> Chunkify(this DataTable table, int chunkSize) { for (int i = 0; i < table.Rows.Count; i += chunkSize) { DataTable Chunk = table.Clone(); foreach (DataRow Row in table.Select().Skip(i).Take(chunkSize)) { Chunk.ImportRow(Row); } yield return Chunk; } } } Example consumer of that extension method, with sample output from an ad hoc test: class Program { static void Main(string[] args) { DataTable Table = GetTonsOfData(); foreach (DataTable Chunk in Table.Chunkify(100)) { Console.WriteLine("{0} - {1}", Chunk.Rows[0][0], Chunk.Rows[Chunk.Rows.Count - 1][0]); } Console.ReadLine(); } static DataTable GetTonsOfData() { DataTable Table = new DataTable(); Table.Columns.Add(new DataColumn()); for (int i = 0; i < 1000; i++) { DataRow Row = Table.NewRow(); Row[0] = i; Table.Rows.Add(Row); } return Table; } }

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• Does Hibernate create tables in the database automatically.

  - by theJava

  http://www.vaannila.com/spring/spring-hibernate-integration-1.html Upon reading this tutorial, they have not mentioned anything over creating tables in the DB. Does the Hibernate handle it automatically by creating tables and fields once i specify them. Here is my beans configuration. <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> <bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://127.0.0.1:3306/spring"/> <property name="username" value="monwwty"/> <property name="password" value="www"/> </bean> <bean id="mySessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="dataSource" ref="myDataSource" /> <property name="annotatedClasses"> <list> <value>uk.co.vinoth.spring.domain.User</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.hbm2ddl.auto">create</prop> </props> </property> </bean> <bean id="myUserDAO" class="uk.co.vinoth.spring.dao.UserDAOImpl"> <property name="sessionFactory" ref="mySessionFactory"/> </bean> <bean name="/user/*.htm" class="uk.co.vinoth.spring.web.UserController" > <property name="userDAO" ref="myUserDAO" /> </bean> </beans>

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