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  • Handling exceptions, is this a good way?

    - by Jorge Córdoba
    We're struggling with a policy to correctly handle exceptions in our application. Here's our goals for it (summarized): Handle only specific exceptions. Handle only exceptions that you can correct Log only once. We've come out with a solution that involves a generic Application Specific Exception and works like this in a piece of code: try { // Do whatever } catch(ArgumentNullException ane) { // Handle, optinally log and continue } catch(AppSpecificException) { // Rethrow, don't log, don't do anything else throw; } catch(Exception e) { // Log, encapsulate (so that it won't be logged again) and throw Logger.Log("Really bad thing", e.Message, e); throw new AppSpecificException(e) } All exception is logged and then turned to an AppSpecificException so that it won't be logged again. Eventually it will reach the last resort event handler that will deal with it if it has to. I don't have so much experience with exception handling patterns... Is this a good way to solve our goals? Has it any major drawbacks or big red warnings?

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  • How to Log Exception in a file?

    - by Ismail
    I want to be able to do logging in every catch block. Something like this. catch (Exception exception) { Logger.Write(exception); } and then the settings in the configuration will pick up the Message and StackTrace property etc using customer listener. I would like to use Enterprise Library Logging Application Block. I'm sure someone must have done this already.

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  • Which web-safe fonts are more readable to eyes as a body text? Which web-safe fonts should not be us

    - by metal-gear-solid
    Which web-safe fonts are more readable to eyes as a body text? Which web-safe fonts should not be used? What should be the minimum font size of <p>body text</p> for better readability? What font size should we use for <H1/2/3/4/5/6>, <p> <ul>, <ol>? Should we use same font-size for <p>, <ul>, <ol> and <th> <td>? What would be the balanced typography font sizing scheme?

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  • How to catch any exception (System.Exception) without a warning in F#?

    - by LLS
    I tried to catch an Exception but the compiler gives warning: This type test or downcast will always hold let testFail () = try printfn "Ready for failing..." failwith "Fails" with | :? System.ArgumentException -> () | :? System.Exception -> () The question is: how to I do it without the warning? (I believe there must be a way to do this, otherwise there should be no warning) Like C# try { Console.WriteLine("Ready for failing..."); throw new Exception("Fails"); } catch (Exception) { }

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  • What are the standard practices for throwing Javascript Exceptions?

    - by T.R.
    w3schools says that exceptions can be strings, integers, booleans, or objects, but the example given doesn't strike me as good practice, since exception type checking is done through string comparison. Is this the preferred method of exception handling in Javascript? Are there built-in exception types (like NullPointerException)? (if so, what are they, what kind of inheritance do they use, and are they preferred over other options?)

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  • try except block in Delphi

    - by Nik
    Do you guys know a way to trap log and re-raise exception in Delphi code. A simple example: procedure TForm3.Button1Click(Sender: TObject); begin try raise Exception.Create('Bum'); except on E: Exception do begin MyHandleException(E); end; end; end; procedure TForm3.MyHandleException(AException: Exception); begin ShowMessage(AException.Message); // raise AException; - this will access violate end; So I need to re-raise it in the except block but I was wondering is there a better way to write my own method to handle and (on specific conditions) to re-raise exceptions?

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  • What are the standard practices for throwing JavasScript Exceptions?

    - by T.R.
    w3schools says that exceptions can be strings, integers, booleans, or objects, but the example given doesn't strike me as good practice, since exception type checking is done through string comparison. Is this the preferred method of exception handling in JavaScript? Are there built-in exception types (like NullPointerException)? (if so, what are they, what kind of inheritance do they use, and are they preferred over other options?)

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  • GPL exception that allows linking to free licenses only?

    - by fNek
    There is the GPL license and the linking exception which allows closed-source programs to use the program as a library. There is also the slightly more restrictive LGPL (more restrictive than GPL with exception since it requires that the user can change the library in the resulting project, etc.). And there is the Cygwin exception that allows linking to open source programs. I see clear advantages: Open-Source programs may use the library. People may use these programs for closed-source programs, but then they lose the permission to use the (GPL) library. However, there are two things I don't like about the Cygwin exception: - Its legal status is disputed - I keep hearing that it is basically worthless - It requires certification by the OSI, I would rather have certification by FSF Is there an exception to the GNU General Public License that meets my requirements?

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  • .NET Process.Kill() in a safe way

    - by Orborde
    I'm controlling a creaky old FORTRAN simulator from a VB.NET GUI, using redirected I/O to communicate with the simulator executable. The GUI pops up a "status" window with a progress bar, estimated time, and a "STOP" button (Button_Stop). Now, I want the Button_Stop to terminate the simulator process immediately. The obvious way to do this is to call Kill() on the Child Process object. This gives an exception if it's done after the process has exited, but I can test whether the process is exited before trying to kill it, right? OK, so I do the following when the button is clicked: If Not Child.HasExited Then Child.Kill() Button_Stop.Enabled = False End If However, what if the process happens to exit between the test and the call to Kill()? In that case, I get an exception. The next thing to occur to me was that I can do Button_Stop.Enabled = False in the Process.Exited event handler, and thus prevent the Child.Kill() call in the Button_Stop.Clicked handler. But since the Process.Exited handler is called on a different thread, that still leaves the following possible interleaving: Child process exits. Process.Exited fires, calls Invoke to schedule the Button_Stop.Enabled = False User clicks on Button_Stop, triggering Child.Kill() Button_Stop.Enabled = False actually happens. An exception would then be thrown on step 3. How do I kill the process without any race conditions? Am I thinking about this entirely wrong?

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  • PHP include() alternative?

    - by Adrian M.
    Hello, I want to know if my code is safe and if there are other safer alternatives to include external files.. So this is my code example, is it safe? How can I make it safer? Thanks! <?php switch($_GET['p']){ case 'test1': include 'test1.php'; break; case 'test2': include 'test2.php'; break; case 'test': echo 'something'; include 'pages/test.php'; echo 'something'; break; default: include 'main.php'; break; } ?>

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  • Unable to start tomcat6: Java error (Exception in thread "main")

    - by Nyxynyx
    After installing tomcat6 on CentOS 6.3, I am unable to start tomcat6 server. root@host [/var/log/tomcat6]# service tomcat6 start Starting tomcat6: [ OK ] Although it says OK, I cant access http://mydomain.com:8080. catalina.out Exception in thread "main" java.lang.NullPointerException at java.lang.VMClassLoader.defineClass(libgcj.so.10) at java.lang.ClassLoader.defineClass(libgcj.so.10) at java.security.SecureClassLoader.defineClass(libgcj.so.10) at java.net.URLClassLoader.findClass(libgcj.so.10) at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.10) at java.lang.ClassLoader.loadClass(libgcj.so.10) at java.lang.ClassLoader.loadClass(libgcj.so.10) at gnu.java.lang.MainThread.run(libgcj.so.10) Tomcat6 was installed using yum: yum -y install java tomcat6 tomcat6-webapps tomcat6-admin-webapps When I tried to find the version: tomcat6 version: Exception in thread "main" java.lang.NoClassDefFoundError: org.apache.catalina.util.ServerInfo at gnu.java.lang.MainThread.run(libgcj.so.10) Caused by: java.lang.ClassNotFoundException: org.apache.catalina.util.ServerInfo not found in gnu.gcj.runtime.SystemClassLoader{urls=[], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}} at java.net.URLClassLoader.findClass(libgcj.so.10) at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.10) at java.lang.ClassLoader.loadClass(libgcj.so.10) at java.lang.ClassLoader.loadClass(libgcj.so.10) at gnu.java.lang.MainThread.run(libgcj.so.10) Any idea what I should do? Thanks!

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  • IIS 6 + ASP.NET web service - DW20 and stackoverflow exception

    - by pcampbell
    Consider an ASP.NET SOAP web service that starts up fine, but craters hard when receiving its first hit. Please note that this is deployment works in the Test environment, but not in the PreProd environment. Both are Windows 2003 SP3 + IIS 6 + ASP.NET 3.5. All up-to-date. The behaviour that we're seeing is: restart the site & app pool the app pool is configured to run under Network Service. browsing to the .asmx and .wsdl responds normally, as expected. send a normal well-formed SOAP request / normal payload to the web service 100% CPU usage after 5 seconds, the page request / site returns "Service Unavailable" no entry is created in the IIS log file (i.e. c:\windows\system32\logfiles\W3C-foo) the app pool ends up being stopped The processes that hit the CPU hard are dw20.exe. I am unsure why Dr Watson is involved here. Event Log shows an ASP.NET Runtime error: Task Manager: Event log text: EventType clr20r3, P1 w3wp.exe, P2 6.0.3790.3959, P3 45d6968e, P4 errormanagement, P5 1.0.0.0, P6 4b86a13f, P7 24, P8 0, P9 system.stackoverflowexception, P10 NIL. Questions Any thoughts on what this system.stackoverflow exception might be? Given that the code is the same between environments, might it be a payload problem? Could it be a configuration issue? You can see the name of my .NET assembly there in the exception message: "ErrorManagement"

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  • jdbc4 CommunicationsException

    - by letronje
    I have a machine running a java app talking to a mysql instance running on the same instance. the app uses jdbc4 drivers from mysql. I keep getting com.mysql.jdbc.exceptions.jdbc4.CommunicationsException at random times. Here is the whole message. Could not open JDBC Connection for transaction; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was25899 milliseconds ago.The last packet sent successfully to the server was 25899 milliseconds ago, which is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem. For mysql, the value of global 'wait_timeout' and 'interactive_timeout' is set to 3600 seconds and 'connect_timeout' is set to 60 secs. the wait timeout value is much higher than the 26 secs(25899 msecs). mentioned in the exception trace. I use dbcp for connection pooling and here is spring bean config for the datasource. <bean id="dataSource" destroy-method="close" class="org.apache.commons.dbcp.BasicDataSource" > <property name="driverClassName" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/db"/> <property name="username" value="xxx"/> <property name="password" value="xxx" /> <property name="poolPreparedStatements" value="false" /> <property name="maxActive" value="3" /> <property name="maxIdle" value="3" /> </bean> Any idea why this could be happening? Will using c3p0 solve the problem ?

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  • How to read cell data in excel and output to command prompt

    - by Max Ollerenshaw
    Hi All, I'm a sys admin and I am trying to learn how to use powershell... I have never done any type of scripting or coding before and I have been teaching myself online by learning from the technet script centre and online forums. What I am trying to accomplish is to open an excel spreadsheet get information from it (usernames and password) and then output it into the command prompt in powershell. When ever I try to do this I get an Exception calling "InvokeMember" anyway, here is the code I have so far: function Invoke([object]$m, [string]$method, $parameters) { $m.PSBase.GetType().InvokeMember( $method, [Reflection.BindingFlags]::InvokeMethod, $null, $m, $parameters,$ciUS ) } $ciUS = [System.Globalization.CultureInfo]'en-US' $objExcel = New-Object -comobject Excel.Application $objExcel.Visible = $False $objExcel.DisplayAlerts = $False $objWorkbook = Invoke $objExcel.Workbooks.Open "C:\PS\User Data.xls" Write-Host "Numer of worksheets: " $objWorkbook.Sheets.Count $objWorksheet = $objWorkbook.Worksheets.Item(1) Write-Host "Worksheet: " $objWorksheet.Name $Forename = $objWorksheet.Cells.Item(2,1).Text $Surname = $objWorksheet.Cells.Item(2,2).Text Write-Host "Forename: " $Forename Write-Host "Surname: " $Surname $objExcel.Quit() If (ps excel) { kill -name excel} I have read many different posts on forums and articles on how to try and get around the en-US problem but I cannot seem to get around it and hope that someone here can help! Here is the Exeption problem I mentioned: Exception calling "InvokeMember" with "6" argument(s): "Method 'System.Management.Automation.PSMethod.C:\PS\User Data.x ls' not found." At C:\PS\excel.ps1:3 char:33 + $m.PSBase.GetType().InvokeMember <<<< ( + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : DotNetMethodException Numer of worksheets: You cannot call a method on a null-valued expression. At C:\PS\excel.ps1:18 char:45 + $objWorksheet = $objWorkbook.Worksheets.Item <<<< (1) + CategoryInfo : InvalidOperation: (Item:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull Worksheet: You cannot call a method on a null-valued expression. At C:\PS\excel.ps1:21 char:37 + $Forename = $objWorksheet.Cells.Item <<<< (2,1).Text + CategoryInfo : InvalidOperation: (Item:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull You cannot call a method on a null-valued expression. At C:\PS\excel.ps1:22 char:36 + $Surname = $objWorksheet.Cells.Item <<<< (2,2).Text + CategoryInfo : InvalidOperation: (Item:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull Forename: Surname: This is the first question I have ever asked, try to be nice! :)) Many Thanks Max

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  • What is causing a Hibernate SQL query exception?

    - by Dark Star1
    Hi all and sorry in advance for this post but I've spent way too much time going around in circles so I'm hoping someone could shed a light on it here for me. I updated a webapp on Tomcat and I'm getting the following error which didn't exist on the previous version. Though I am quite confident that the part of code I modifed isn't to blame as I have tested the app on two different dev servers. The production server is configured thus: CentOS 5.4 virtual server with tomcat 5.5.23 running mysql 5.0.77. The two dev servers are: Windows XP SP2 running tomcat 5.5.23 with mysql 5.1.49 Mac OSX 10.6.6 Running tomcat 6 with mysql 5.1.51 The application was developed using struts (1.1 as far as I can gather) with hibernate 3 as the peristence layer. It only fails on the production server for some reason I can't fathom. I'd like to draw your attention to the java.sql.SQLException near the bottom. After some long searching I found this but because it was posted years ago (about 1 year before development started on this app I'm sure Hibernate has evolved from that version. as I can't find a way of implementing his solution. I use Eclipse Helios as an IDE. Thanks in advance for taking your time to read this, to all who manage to reply. javax.servlet.ServletException: org.hibernate.exception.SQLGrammarException: could not execute query at fr.company.action.login.LoginAction.execute(LoginAction.java:219) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525) 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:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at fr.company.util.EncodingFilter.doFilter(EncodingFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:113) at java.lang.Thread.run(Thread.java:636) javax.servlet.ServletException: org.hibernate.exception.SQLGrammarException: could not execute query at fr.company.action.login.LoginAction.execute(LoginAction.java:219) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525) 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:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at fr.company.util.EncodingFilter.doFilter(EncodingFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:113) at java.lang.Thread.run(Thread.java:636) java.lang.Exception: org.hibernate.exception.SQLGrammarException: could not execute query at fr.company.dao.GenericDAO.findOne(GenericDAO.java:204) at fr.company.dao.UserDAO.findOneUser(UserDAO.java:146) at fr.company.service.UserPeer.logUser(UserPeer.java:72) at fr.company.action.login.LoginAction.execute(LoginAction.java:127) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525) 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:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at fr.company.util.EncodingFilter.doFilter(EncodingFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:113) at java.lang.Thread.run(Thread.java:636) Caused by: org.hibernate.exception.SQLGrammarException: could not execute query at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:65) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) at org.hibernate.loader.Loader.doList(Loader.java:2153) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2029) at org.hibernate.loader.Loader.list(Loader.java:2024) at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:369) at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:300) at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:153) at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1128) at org.hibernate.impl.QueryImpl.list(QueryImpl.java:79) at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:749) at fr.company.dao.GenericDAO.findOne(GenericDAO.java:198) ... 26 more Caused by: java.sql.SQLException: Unknown column 'user0_1_.poloSize' in 'field list' at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2928) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1571) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1666) at com.mysql.jdbc.Connection.execSQL(Connection.java:2994) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:936) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1030) at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76) at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:139) at org.hibernate.loader.Loader.getResultSet(Loader.java:1669) at org.hibernate.loader.Loader.doQuery(Loader.java:662) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224) at org.hibernate.loader.Loader.doList(Loader.java:2150) ... 35 more

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  • Is Structuremap singleton thread safe?

    - by Ben
    Hi, Currently I have the following class: public class PluginManager { private static bool s_initialized; private static object s_lock = new object(); public static void Initialize() { if (!s_initialized) { lock (s_lock) { if (!s_initialized) { // initialize s_initialized = true; } } } } } The important thing here is that Initialize() should only be executed once whilst the application is running. I thought that I would refactor this into a singleton class since this would be more thread safe?: public sealed class PluginService { static PluginService() { } private static PluginService _instance = new PluginService(); public static PluginService Instance { get { return _instance; } } private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } Question one, is it still necessary to have the lock here (I have removed it) since we will only ever be working on the same instance? Finally, I want to use DI and structure map to initialize my servcices so I have refactored as below: public interface IPluginService { void Initialize(); } public class NewPluginService : IPluginService { private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } And in my registry: ForRequestedType<IPluginService>() .TheDefaultIsConcreteType<NewPluginService>().AsSingletons(); This works as expected (singleton returning true in the following code): var instance1 = ObjectFactory.GetInstance<IPluginService>(); var instance2 = ObjectFactory.GetInstance<IPluginService>(); bool singleton = (instance1 == instance2); So my next question, is the structure map solution as thread safe as the singleton class (second example). The only downside is that this would still allow NewPluginService to be instantiated directly (if not using structure map). Many thanks, Ben

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  • Is NSPasteboard thread-safe?

    - by Joe
    Is it safe to write data to an NSPasteboard object from a background thread? I can't seem to find a definitive answer anywhere. I think the assumption is that the data will be written to the pasteboard before the drag begins. Background: I have an application that is fetching data from Evernote. When the application first loads, it gets the meta data for each note, but not the note content. The note stubs are then listed in an outline view. When the user starts to drag a note, the notes are passed to the background thread that handles getting the note content from Evernote. Having the main thread block until the data is gotten results in a significant delay and a poor user experience, so I have the [outlineView:writeItems:toPasteboard:] function return YES while the background thread processes the data and invokes the main thread to write the data to the pasteboard object. If the note content gets transferred before the user drops the note somewhere, everything works perfectly. If the user drops the note somewhere before the data has been processed... well, everything blocks forever. Is it safe to just have the background thread write the data to the pasteboard?

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  • Thread safe lazy contruction of a singleton in C++

    - by pauldoo
    Is there a way to implement a singleton object in C++ that is: Lazily constructed in a thread safe manner (two threads might simultaneously be the first user of the singleton - it should still only be constructed once). Doesn't rely on static variables being constructed beforehand (so the singleton object is itself safe to use during the construction of static variables). (I don't know my C++ well enough, but is it the case that integral and constant static variables are initialized before any code is executed (ie, even before static constructors are executed - their values may already be "initialized" in the program image)? If so - perhaps this can be exploited to implement a singleton mutex - which can in turn be used to guard the creation of the real singleton..) Excellent, it seems that I have a couple of good answers now (shame I can't mark 2 or 3 as being the answer). There appears to be two broad solutions: Use static initialisation (as opposed to dynamic initialisation) of a POD static varible, and implementing my own mutex with that using the builtin atomic instructions. This was the type of solution I was hinting at in my question, and I believe I knew already. Use some other library function like pthread_once or boost::call_once. These I certainly didn't know about - and am very grateful for the answers posted.

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  • P/Invoke declarations should not be safe-critical

    - by Bobrovsky
    My code imports following native methods: DeleteObject, GetFontData and SelectObject from gdi32.dll GetDC and ReleaseDC from user32.dll I want to run the code in full trust and medium trust environments (I am fine with exceptions being thrown when these imported methods are indirectly used in medium trust environments). When I run Code Analysis on the code I get warnings like: CA5122 P/Invoke declarations should not be safe-critical. P/Invoke method 'GdiFont.DeleteObject(IntPtr)' is marked safe-critical. Since P/Invokes may only be called by critical code, this declaration should either be marked as security critical, or have its annotation removed entirely to avoid being misleading. Could someone explain me (in layman terms) what does this warning really mean? I tried putting these imports in static SafeNativeMethods class as internal static methods but this doesn't make the warnings go away. I didn't try to put them in NativeMethods because after reading this article I am unsure that it's the right way to go because I don't want my code to be completely unusable in medium trust environments (I think this will be the consequence of moving imports to NativeMethods). Honestly, I am pretty much confused about the real meaning of the warning and consequences of different options to suppressing it. Could someone shed some light on all this? EDIT: My code target .NET 2.0 framework. Assembly is marked with [assembly: AllowPartiallyTrustedCallers] Methods are declared like this: [DllImport("gdi32")] internal static extern int DeleteObject(HANDLE hObject);

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  • Is private method in spring service implement class thread safe

    - by Roger Ray
    I got a service in an project using Spring framework. public class MyServiceImpl implements IMyService { public MyObject foo(SomeObject obj) { MyObject myobj = this.mapToMyObject(obj); myobj.setLastUpdatedDate(new Date()); return myobj; } private MyObject mapToMyObject(SomeObject obj){ MyObject myojb = new MyObject(); ConvertUtils.register(new MyNullConvertor(), String.class); ConvertUtils.register(new StringConvertorForDateType(), Date.class); BeanUtils.copyProperties(myojb , obj); ConvertUtils.deregister(Date.class); return myojb; } } Then I got a class to call foo() in multi-thread; There goes the problem. In some of the threads, I got error when calling BeanUtils.copyProperties(myojb , obj); saying Cannot invoke com.my.MyObject.setStartDate - java.lang.ClassCastException@2da93171 obviously, this is caused by ConvertUtils.deregister(Date.class) which is supposed to be called after BeanUtils.copyProperties(myojb , obj);. It looks like one of the threads deregistered the Date class out while another thread was just about to call BeanUtils.copyProperties(myojb , obj);. So My question is how do I make the private method mapToMyObject() thread safe? Or simply make the BeanUtils thread safe when it's used in a private method. And will the problem still be there if I keep the code this way but instead I call this foo() method in sevlet? If many sevlets call at the same time, would this be a multi-thread case as well?

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  • Is it safe to use a boolean flag to stop a thread from running in C#

    - by Lirik
    My main concern is with the boolean flag... is it safe to use it without any synchronization? I've read in several places that it's atomic. class MyTask { private ManualResetEvent startSignal; private CountDownLatch latch; private bool running; MyTask(CountDownLatch latch) { running = false; this.latch = latch; startSignal = new ManualResetEvent(false); } // A method which runs in a thread public void Run() { startSignal.WaitOne(); while(running) { startSignal.WaitOne(); //... some code } latch.Signal(); } public void Stop() { running = false; startSignal.Set(); } public void Start() { running = true; startSignal.Set(); } public void Pause() { startSignal.Reset(); } public void Resume() { startSignal.Set(); } } Is this a safe way to design a task? Any suggestions, improvements, comments? Note: I wrote my custom CountDownLatch class in case you're wondering where I'm getting it from.

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  • Is this a safe PHP mail function?

    - by Eystein
    I've finally got this PHP email script working (didn't work on localhost…), but my concern is that it's not safe. So - is this safe for spamming and any other security pitfalls I'm not aware of? <?php $email = '[email protected]'; $subject = 'Notify about stuff'; $notify = $_REQUEST['email']; if (!preg_match("/\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/", $notify)) { echo "<h4>Your email address doesn't validate, please check that you typed it correct.</h4>"; echo "<a href='javascript:history.back(1);'>Back</a>"; } elseif(mail($email, $subject, $notify)) { echo "<h4>Thank you, you will be notified.</h4>"; } else { echo "<h4>Sorry, your email didn't get registered.</h4>"; } ?> Unrelated: is there a PHP function I can use instead of javascript:history.back(1) ?

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  • whether rand_r is real thread safe?

    - by terry
    Well, rand_r function is supposed to be a thread safe function. However, by its implementation, I cannot believe it could make itself not change by other threads. Suppose that two threads will invoke rand_r in the same time with the same variable seed. So read-write race will occur. The code rand_r implemented by glibc is listed below. Anybody knows why rand_r is called thread safe? int rand_r (unsigned int *seed) { unsigned int next = *seed; int result; next *= 1103515245; next += 12345; result = (unsigned int) (next / 65536) % 2048; next *= 1103515245; next += 12345; result <<= 10; result ^= (unsigned int) (next / 65536) % 1024; next *= 1103515245; next += 12345; result <<= 10; result ^= (unsigned int) (next / 65536) % 1024; *seed = next; return result; }

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  • Is Storing Cookies in a Database Safe?

    - by viatropos
    If I use mechanize, I can, for instance, create a new google analytics profile for a website. I do this by programmatically filling out the login form and storing the cookies in the database. Then, for at least until the cookie expires, I can access my analytics admin panel without having to enter my username and password again. Assuming you can't create a new analytics profile any other way (with OpenAuth or any of that, I don't think it works for actually creating a new Google Analytics profile, the Analytics API is for viewing the data, but I need to create an new analytics profile), is storing the cookie in the database a bad thing? If I do store the cookie in the database, it makes it super easy to programatically login to Google Analytics without the user ever having to go to the browser (maybe the app has functionality that says "user, you can schedule a hook that creates a new anaytics profile for each new domain you create, just enter your credentials once and we'll keep you logged in and safe"). Otherwise I have to keep transferring around emails and passwords which seems worse. So is storing cookies in the database safe?

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