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  • VB.net: Is my Thread Safe List Solution actually safe?

    - by Shiftbit
    I've added teh following Extensions to my Project in order to create a thread safe list: Extensions If I want to conduct a simple operation on my list <Extension()> _ Public Sub Action(Of T)(ByVal list As List(Of T), ByVal action As Action(Of List(Of T))) SyncLock (list) action(list) End SyncLock End Sub If I want to pass it more than one parameter I could simply extend it with more items... <Extension()> _ Public Sub Action(Of T)(ByVal list As List(Of T), ByVal action As Action(Of List(Of T), T), ByVal item As T) SyncLock (list) Action(list, item) End SyncLock End Sub Actions I have created the following Action Examples: Private Sub Read(Of T)(ByVal list As List(Of T)) Console.WriteLine("Read") For Each item As T In list Console.WriteLine(item.ToString) Thread.Sleep(10) Next End Sub and also one that takes a parameter: Private Sub Write(Of T)(ByVal list As List(Of T), ByVal item As T) Thread.Sleep(100) list.Add(item) Console.WriteLine("Write") End Sub Initiating Then in my various threads I will call my Actions with: list.Action(AddressOf Read) or list.Action(AddressOf Write2, 10) Are these Extenxion methods thread safe or do you have other recommendations?

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  • How to simulate OutOfMemory exception

    - by Gacek
    I need to refactor my project in order to make it immune to OutOfMemory exception. There are huge collections used in my project and by changing one parameter I can make my program to be more accurate or use less of the memory... OK, that's the background. What I would like to do is to run the routines in a loop: Run the subroutines with the default parameter. Catch the OutOfMemory exception, change the parameter and try to run it again. Do the 2nd point until parameters allow to run the subroutines without throwing the exception (usually, there will be only one change needed). Now, I would like to test it. I know, that I can throw the OutOfMemory exception on my own, but I would like to simulate some real situation. So the main question is: Is there a way of setting some kind of memory limit for my program, after reaching which the OutOfMemory exception will be thrown automatically? For example, I would like to set a limit, let's say 400MB of memory for my whole program to simulate the situation when there is such an amount of memory available in the system. Can it be done?

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  • localtime_r supposed to be thread safe, but causing errors in Valgrind DRD

    - by Nik
    I searched google as much as I could but I couldn't find any good answers to this. localtime_r is supposed to be a thread-safe function for getting the system time. However, when checking my application with Valgrind --tool=drd, it consistantly tells me that there is a data race condition on this function. Are the common search results lying to me, or am I just missing something? It doesn't seem efficient to surround each localtime_r call with a mutex, especially if it is supposed to by thread safe in the first place. here is how i'm using it: timeval handlerTime; gettimeofday(&handlerTime,NULL); tm handlerTm; localtime_r(&handlerTime.tv_sec,&handlerTm); Any ideas?

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  • Exception handling in Boost.Asio

    - by Alex B
    Boost.Asio documentation suggests the following exception handling pattern: boost::asio::io_service io_service; ... for (;;) { try { io_service.run(); break; // run() exited normally } catch (my_exception& e) { // Deal with exception as appropriate. } } The problem with it is that the context of exception is lost at the point when it's handled. For example, if I have multiple socket sessions going on, I don't know which one caused the exception to be thrown. What would be a better way to handle the exceptions from asynchronous handlers without wrapping them in try/catch blocks?

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  • Exception thrown when using WScript via COM in PHP

    - by user198729
    try { $cmd = 'php path_to_file.php args'; $WshShell = new COM("WScript.Shell"); $oExec = $WshShell->Run($cmd, 1, false); } catch( Exception $e ) { echo 'Caught exception: ', $e->getMessage(), "\n"; } It reports: Caught exception: Source: Unknown Description: Unknown Has anyone met this kind of problem ?

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  • Calling the LWRP from the Exception Handler

    - by Sarah Haskins
    Is it possible to call out to a Provider (LWRP) from a Chef Exception Handler? I think my Provider is out of scope, but I don't know if what I am trying to do is possible? or advisable? Here is my provider code (cookbooks/config/provider/signal.rb): action :failure do Chef::Log.info("Yeah success") end Here is my exception handler code (exception_handler/handlers/exceptionHandler.rb): require 'chef/handler' config_signal "signal" do action :nothing end class Chef class Handler class LogCollector < Chef::Handler notifies :failure, resources(:config_signal => signal) end end end Also, if anyone has a good recommendation for general reading about scope in the context of Chef I'd appreciate it.

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  • The uncatchable exception, pt 2

    - by chaiguy
    Ok I've done some testing and I've reduced the problem to something very simple: i. Create a method in a new class that throws an exception: public class Class1 { public void CallMe() { string blah = null; blah.ToLower(); } } ii. Create a MethodInfo that points to this method somewhere else: Type class1 = typeof( Class1 ); Class1 obj = new Class1(); MethodInfo method = class1.GetMethod( "CallMe" ); iii. Wrap a call to Invoke() in a try/catch block: try { method.Invoke( obj, null ); // exception is not being caught! } catch { } iv. Run the program without the debugger (works fine). v. Now run the program with the debugger. The debugger will halt the program when the exception occurs, even though it's wrapped in a catch handler that tries to ignore it. (Even if you put a breakpoint in the catch block it will halt before it reaches it!) In fact, the exception is happening when you run it without the debugger too. In a simple test project it's getting ignored at some other level, but if your app has any kind of global exception handling, it will get triggered there as well. This is causing me a real headache because it keeps triggering my app's crash-handler, not to mention the pain it is to attempt to debug.

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  • Thoughts on try-catch blocks

    - by John Boker
    What are your thoughts on code that looks like this: public void doSomething() { try { // actual code goes here } catch (Exception ex) { throw; } } The problem I see is the actual error is not handled, just throwing the exception in a different place. I find it more difficult to debug because i don't get a line number where the actual problem is. So my question is why would this be good? ---- EDIT ---- From the answers it looks like most people are saying it's pointless to do this with no custom or specific exceptions being caught. That's what i wanted comments on, when no specific exception is being caught. I can see the point of actually doing something with a caught exception, just not the way this code is.

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  • Which framework exceptions should every programmer know about ?

    - by Thibault Falise
    I've recently started a new project in C#, and, as I was coding some exception throw in a function, I figured out I didn't really know which exception I should use. Here are common exceptions that are often thrown in many programs : ArgumentException ArgumentNullException InvalidOperationException Are there any framework exceptions you often use in your programs ? Which exceptions should every .net programmer know about ? When do you use custom exception ?

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  • Logging exceptions to database in NServiceBus

    - by IGoor
    If an exception occurs in my MessageHandler I want to write the exception details to my database. How do I do this? Obviously, I cant just catch the exception, write to database, and rethrow it since NSB rollbacks all changes. (IsTransactional is set to true) I tried adding logging functionality in a seperate handler, which I caledl using SendLocal if an exception occured, but this does not work: public void Handle(MessageItem message) { try { DoWork(); } catch(Exception exc) { Bus.SendLocal(new ExceptionMessage(exc.Message)); throw; } } I also tried using Log4Net with a custom appender, but this also rolled back. Configure.With() .Log4Net<DatabaseAppender>(a => a.Log = "Log") appender: public class DatabaseAppender : log4net.Appender.AppenderSkeleton { public string Log { get; set; } protected override void Append(log4net.Core.LoggingEvent loggingEvent) { if (loggingEvent.ExceptionObject != null) WriteToDatabase(loggingEvent.ExceptionObject); } } Is there anyway to log unhandled exceptions in the messagehandler when IsTransactional is true? Thanks in advance.

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  • not output exception stack trace in EUnit

    - by hpyhacking
    I'm write a test with EUnit, but not anything exception detail output in console. exp_test() -> ?assertEqual(0, 1/0). Run this module:exp_test() in the Erlang Shell output following ** exception error: bad argument in an arithmetic expression in function exp_test:'-exp_test/0-fun-0-'/1 (src/test/eunit/xxx_test.erl, line 8) But in EUnit output following > eunit:test(xxx). > xxx_test: exp_test...*failed* ::badarith EUnit not output anything exception trace info Im trying the verbose config in eunit, but no effect. I want to output some exception detail in eunit test result. Thanks~

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  • Communication between layers in an application

    - by Petar Minchev
    Hi guys! Let's assume we have the following method in the business layer. What's the best practice to tell the UI layer that something went wrong and give also the error message? Should the method return an empty String when it was OK, otherwise the error message, or should it throw another exception in the catch code wrapping the caught exception? If we choose the second variant then the UI should have another try,catch which is too much try,catch maybe. Here is a pseudocode for the first variant. public String updateSomething() { try { //Begin transaction here dataLayer.do1(); dataLayer.do2(); dataLayer.doN(); } catch(Exception exc) { //Rollback transaction code here return exc.message; } return ""; } Is this a good practice or should I throw another exception in the catch(then the method will be void)?

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  • How to handle all exceptions in a web java project

    - by Nick Donovan
    I am doing an web java project about an hotel reservation. I am using, sql, hibernate, java server pages. I want to know how can I redirect an incoming exception to an error.jsp file . There are a lot of java code , and a lot of jsp file. So I want to rederict every exception that I haven't handle to an error page, is there any way to do it ? An exception can come from everywhere and I can't know and handle them all ( for example an user can write to much data in an textfield, and it will generate me an sql exception for data to long) Thank you, sorry for my english.

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  • Exception in inserting data into data using JPA in netbeans

    - by sandeep
    SEVERE: Local Exception Stack: Exception [EclipseLink-7092] (Eclipse Persistence Services - 2.0.0.v20091127-r5931): org.eclipse.persistence.exceptions.ValidationException Exception Description: Cannot add a query whose types conflict with an existing query. Query To Be Added: [ReadAllQuery(name="Voter.findAll" referenceClass=Voter jpql="SELECT v FROM Voter v")] is named: [Voter.findAll] with arguments [[]].The existing conflicting query: [ReadAllQuery(name="Voter.findAll" referenceClass=Voter jpql="SELECT v FROM Voter v")] is named: [Voter.findAll] with arguments: [[]].

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  • javax.persistence.NoResultException: getSingleResult() did not retrieve any entities

    - by apple1988
    Hello, i have created a namedquery with ejb to check if the username is used. When the singleResult is null, then i get the following Exception : javax.persistence.NoResultException: getSingleResult() did not retrieve any entities But this exception is the result that i want when the username is free. ^^ Here is the code: public User getUserByUsername(String username) throws DAOException{ try{ Query q = em.createNamedQuery(User.getUserByUsername); q.setParameter("username", username); return (User) q.getSingleResult(); }catch(Exception e){ throwException(username, e); return null; } } Does anybody know what the problem is. :( I will return null andy don`t get an Exception. Thank you very much

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  • How do I fix this Django error "Exception Type: OperationalError Exception Value: no such table?"

    - by user319045
    I've finally installed all the requirements (so i think!) of a Django project, and I'm trying to get a local install running on my Mac (OSX 10.4). I'm getting the following error: Blockquote OperationalError at / no such table: django_content_type Request Method: GET Request URL: http://127.0.0.1:8000/ Exception Type: OperationalError Exception Value: no such table: django_content_type Exception Location: /Users/Diesel/Desktop/DjangoWork/pinax-ev/lib/python2.5/site-packages/django/db/backends/sqlite3/base.py in execute, line 170 Python Executable: /Users/Diesel/Desktop/DjangoWork/pinax-ev/bin/python Python Version: 2.5.1

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  • Method return values and exceptions

    - by dnagirl
    I have an interface called iIncident which defines a single method when(). when() should return a DateTime object. I'm trying to decide what to do if $object->when() has no DateTime to return as might be the case just after an object is instantiated and before all its properties are set. My choices are: return false throw some kind of Exception return some default DateTime like '9999-01-01' My inclination is to go with an Exception since $object really can't act as an incident until it knows when it occurred. I don't want to return a default DateTime because it complicates comparisons and it's not true. And I don't really want to return false because then I have to check for it every time I call the method- but if that is the preferred method, I guess I will. Is throwing an exception the best way? And is there a predefined exception type I should use (none of the SPL ones struck me as particularly appropriate- but that might just indicate my lack of experience)?

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  • iphone dev - how to catch exception 'NSRangeException'

    - by Brian
    In my app I try to scroll a UITableView to the top once after I updated the content of the table. However, under some circumstance, my table is EMPTY. So I got the following exception: Terminating app due to uncaught exception 'NSRangeException', reason: '-[UITableView scrollToRowAtIndexPath:atScrollPosition:animated:]: row (0) beyond bounds (0) for section (0).' how can I catch this exception? I tried NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0]; if (indexPath != nil) { [EventTable scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES]; } but it doesn't catch the exception because indexPath is not nil.

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  • Win32 Thread Exits Unexpectedly

    - by sahs
    Hello, I'm writing a C++ application. I realized that one of my worker threads may terminate unexpectedly. The (VS 2005) debug log says: The thread 'Win32 Thread' (0x5d98) has exited with code -858993460 (0xcccccccc). I surrounded all the worker thread code with a try/catch block. So, if the reason was an exception, I would catch it. But I can't: try{ ... Connection* conn = connectionPool->getConnection(); // unexpected exit occurs here ... } catch(exception& e) { ... } I have ten threads running concurrently, and only one of them gets crashed after some time, while the others continue running (and getting new [OCCI] connections). Is there an exception type that is not caught by "exception"? Or what do I not know about threads/exceptions? Thanks.

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  • NUnit: Assert.Throws

    - by epitka
    How do I use Assert.Throws to assert type of the exception and the actual message workding. Something like this: Assert.Throws<Exception>( ()=>user.MakeUserActive()).WithMessage("Actual exception message") Method I am testing throws multiple messages of the same type, with different message and I need a way to test that correct message is thrown depending on the context.

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  • Equivalent of IllegalArgumentException of Java in C++

    - by vito
    In Java if an input argument to a method is invalid, we can throw an IllegalArgumentException (which is of type RuntimeException). In C++, there is no notion of checked and unchecked exceptions. Is there a similar exception in standard C++ which can be used to indicate a runtime exception? Or is there a common style not in the standard but everyone follows in practice for a situation like this? Or, should I just create my own custom exception and throw it?

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  • Fault exception trashes a register causing a crash in [NSInvocation invoke]

    - by Mike Weller
    I have an NSOperation which fetches some objects from a core data persistent store and sums up a few totals. Sometimes an object is deleted while the operation in in progress, so a core data fault exception occurs. I try/catch the exception while summing to ignore it because I just want to skip objects that cannot be faulted in. However, when one of these fault exceptions occurs (and I swallow it) there is a crash after the invocation returns in [NSInvocation invoke]. It's a bad memory access when dereferencing the value in r10 which according to GDB on a successful run points to one of these: (gdb) x 0x38388348 0x38388348 <OBJC_IVAR_$_NSInvocation._retdata>: 0x00000008 If a fault exception occured a value of 0x02 is in the register which causes the crash. A quick google search tells me that r10 should be saved by the callee, meaning it is not being restored by whatever code is changing it when this exception occurs. Can anybody explain this? I'm not an expert when it comes to these kinds of low-level details

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  • How do I 'globally' catch exceptions thrown in object instances.

    - by SleepyBobos
    I am currently writing a winforms application (C#). I am making use of the Enterprise Library Exception Handling Block, following a fairly standard approach from what I can see. IE : In the Main method of Program.cs I have wired up event handler to Application.ThreadException event etc. This approach works well and handles the applications exceptional circumstances. In one of my business objects I throw various exceptions in the Set accessor of one of the objects properties set { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum trim..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message..."); _minimumTrim = value; } My logic for this approach (without turning this into a 'when to throw exceptions' discussion) is simply that the business objects are responsible for checking business rule constraints and throwing an exception that can bubble up and be caught as required. It should be noted that in the UI of my application I do explictly check the values that the public property is being set to (and take action there displaying friendly dialog etc) but with throwing the exception I am also covering the situation where my business object may not be used by a UI eg : the Property is being set by another business object for example. Anyway I think you all get the idea. My issue is that these exceptions are not being caught by the handler wired up to Application.ThreadException and I don't understand why. From other reading I have done the Application.ThreadException event and it handler "... catches any exception that occurs on the main GUI thread". Are the exceptions being raised in my business object not in this thread? I have not created any new threads. I can get the approach to work if I update the code as follows, explicity calling the event handler that is wired to Application.ThreadException. This is the approach outlined in Enterprise Library samples. However this approach requires me to wrap any exceptions thrown in a try catch, something I was trying to avoid by using a 'global' handler to start with. try { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message"); _minimumTrim = value; } catch (Exception ex) { Program.ThreadExceptionHandler.ProcessUnhandledException(ex); } I have also investigated using wiring a handler up to AppDomain.UnhandledException event but this does not catch the exceptions either. I would be good if someone could explain to me why my exceptions are not being caught by my global exception handler in the first code sample. Is there another approach I am missing or am I stuck with wrapping code in try catch, shown above, as required?

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