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• How might I schedule a C# Windows Service to perform a task daily?

  - by ctrlalt3nd

  I have a service written in C# (.NET 1.1) and want it to perform some cleanup actions at midnight every night. I have to keep all code contained within the service, so what's the easiest way to accomplish this? Use of Thread.Sleep() and checking for the time rolling over?

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• Synchronous database reads inside IHttpAsyncHandler

  - by sayao

  On asp.net if i call a synchronous database query inside an IHttpAsyncHandler with delegate.BeginInvoke, would it still release the asp.net worker thread while reading the database? For example, this post: http://madskristensen.net/post/How-to-use-the-IHttpAsyncHandler-in-ASPNET.aspx If i put a synchronous database call inside ServeContent, would the request still happen asynchronously?

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• Hosted SVN - RepositoryHosting.com

  - by SVN User

  I'm currently reviewing repositoryhosting.com for possibly hosting our company code, however, I'm weary about pushing forward for a few reasons. First, if the company goes under, I have no assurance that I will have access to grab backups of the code prior. Secondly, their terms state this: "User agrees that Repository Hosting shall not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, including but not limited to, damages for loss of profits, goodwill, use, data or other intangible losses resulting from the use of or inability to use the Service." Basically, I want to ensure that our data is safe. I understand that they do offsite backups and such, however, if there were to be a catastrophic loss of data that was their fault, would we be left with just a "sorry"? What about your thoughts on hosted svn and is it better to just continue to do it yourself?

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• Abnormally disconnected TCP sockets and write timeout

  - by James

  Hello I will try to explain the problem in shortest possible words. I am using c++ builder 2010. I am using TIdTCPServer and sending voice packets to a list of connected clients. Everything works ok untill any client is disconnected abnormally, For example power failure etc. I can reproduce similar disconnect by cutting the ethernet connection of a connected client. So now we have a disconnected socket but as you know it is not yet detected at server side so server will continue to try to send data to that client too. But when server try to write data to that disconnected client ...... Write() or WriteLn() HANGS there in trying to write, It is like it is wating for somekind of Write timeout. This hangs the hole packet distribution process as a result creating a lag in data transmission to all other clients. After few seconds "Socket Connection Closed" Exception is raised and data flow continues. Here is the code try { EnterCriticalSection(&SlotListenersCriticalSection); for(int i=0;i<SlotListeners->Count;i++) { try { //Here the process will HANG for several seconds on a disconnected socket ((TIdContext*) SlotListeners->Objects[i])->Connection->IOHandler->WriteLn("Some DATA"); }catch(Exception &e) { SlotListeners->Delete(i); } } }__finally { LeaveCriticalSection(&SlotListenersCriticalSection); } Ok i already have a keep alive mechanism which disconnect the socket after n seconds of inactivity. But as you can imagine, still this mechnism cant sync exactly with this braodcasting loop because this braodcasting loop is running almost all the time. So is there any Write timeouts i can specify may be through iohandler or something ? I have seen many many threads about "Detecting disconnected tcp socket" but my problem is little different, i need to avoid that hangup for few seconds during the write attempt. So is there any solution ? Or should i consider using some different mechanism for such data broadcasting for example the broadcasting loop put the data packet in some kind of FIFO buffer and client threads continuously check for available data and pick and deliver it to themselves ? This way if one thread hangs it will not stop/delay the over all distribution thread. Any ideas please ? Thanks for your time and help. Regards Jams

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• Securing files on IPhone

  - by clearbrian

  Hi Is there a way to decompile the binary from an IPhone app. I jailbroke my IPhone and was surprised to find other app's dbs wide open to be copied. So I exported my most important table and hardcoded it into code. Instead of loading table into array from a db I just generated code to fill the array and kept only the most basic DB info so relationships still work. Took a while but now works fine. I was just wondering am I safe, could someone decompile the binary for the app easily and extract the data. In Java its easy to decompile *.class files though thats bytecode where I presume iphone apps are more low level. I know IPhone sdk 4 can mark files as secure. Anyone know can this be overridden by jailbreaks or is this an unix lock?

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• Error Exception 2048 on my website using OpenClassifieds software

  - by Rich Baxter

  I have a website called e-waitress.net, it is a jobs employment website for the restaurant industry. I installed an open source program called OpenClassifieds and a couple days after installing the OpenClassifieds, I get an error message when I enter my url that is this: ErrorException [ 2048 ]: date_default_timezone_get(): It is not safe to rely on the system's timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EDT/-4.0/DST' instead ~ APPPATH/ko322/classes/kohana/date.php [ 592 ] I am wondering is this a server issue with my host provider or is it within the OpenClassifieds installation software? I've reinstalled the software twice and it's returned this error after a couple days of working great. Any ideas?

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• How does JVM handles dynamic allocation

  - by Nile

  I want to understand how JVM manages heap for the dynamic allocations. Since every java program is invoked as a thread, when does JVM's garbage collector come into play. Also, how things work for javascript's dynamic allocation ?

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• Is there any cross-platform threading library in C or C++?

  - by NumberFour

  Hello, I'm looking for some easy to use cross-platform threading library written in C or C++. What's your opinion on boost::thread or Pthreads? Does Pthreads run only on POSIX compliant systems? What about the threading support in the Qt library? Thanks for any hints.

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• Your creative PHP Obfuscation - Dynamic Variables

  - by Email

  Hi No thread about use or unuse of obfuscusion please ^^ Just share creative approaches how to obfuscate in php the really smart way plz. plain md5 and base64_decode is too static .. what you think regarding hash, salt what about dynamic Variables (even for the same $var). Thx for any creative input

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• How to properly reserve identity values for usage in a database?

  - by esac

  We have some code in which we need to maintain our own identity (PK) column in SQL. We have a table in which we bulk insert data, but we add data to related tables before the bulk insert is done, thus we can not use an IDENTITY column and find out the value up front. The current code is selecting the MAX value of the field and incrementing it by 1. Although there is a highly unlikely chance that two instances of our application will be running at the same time, it is still not thread-safe (not to mention that it goes to the database everytime). I am using the ADO.net entity model. How would I go about 'reserving' a range of id's to use, and when that range runs out, grab a new block to use, and guarantee that the same range will not be used.

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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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• Attaching files to WCF REST service responses

  - by David Seiler

  I have a resource that looks something like this: /users/{id}/summary?format={format} When format is "xml" or "json" I respond with a user summary object that gets automagically encoded by WCF - fine so far. But when format equals "pdf", I want my response to consist of a trivial HTTP response body and a PDF file attachment. How is this done? Hacking on WebOperationContext.Current.OutgoingResponse doesn't seem to work, and wouldn't be the right thing even if it did. Including the bits of the file in a CDATA section or something in the response isn't safe. Should I create a subclass of Message, then provide a custom IDispatchMessageFormatter that responds with it? I went a short distance down that path but ultimately found the documentation opaque. What's the right thing?

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• how to show a UTC time as local time in a webpage

  - by Retrocoder

  I have a database that holds a time as UTC. This time can be shown in a webpage, so I’ve been asked to show it as local time in the page as it can be viewed from any country. A colleague mentioned something about getting the country settings from the current thread but I couldn’t find any details on this. Is what I want to do possible?

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• Opengl-es android best way to preload images

  - by lacas

  I have a game app, and i have many screens. The first screen will be the SCREEN.LOADING screen. When the app starting, I want to show a picture "loading please wait" while the images, menus, etc loaded succesfull. I tried asynctask to do this, but its not work in GLThread. What is the way to do this in opengl-es? 03-06 12:46:35.282: ERROR/AndroidRuntime(32736): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() Thanks, Leslie

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• Fast response on first Socket I/O request but slow every other time when communicating with remote serial port

  - by GreenGodot

  I'm using sockets to pass Serial commands to a remote device. And the response to that request is sent back and printed out. However, I am having a problem in that the first time it is instant but the rest of the time it can take up to 20 seconds to receive a reply. I think the problem is with my attempt at threading but I am not entirely sure. new Thread() { @Override public void run() { System.out.println("opened"); try { isSocketRetrieving.setText("Opening Socket"); socket = new Socket(getAddress(), getRemotePort())); DataOutput = new DataOutputStream(socket .getOutputStream()); inFromServer = new BufferedReader( new InputStreamReader(socket .getInputStream())); String line = ""; isSocketRetrieving.setText("Reading Stream......"); while ((line = inFromServer.readLine()) != null) { System.out.println(line); if (line.contains(getHandshakeRequest())) { DataOutput.write((getHandshakeResponse()toString() + "\r").getBytes()); DataOutput.flush(); DataOutput .write((getCommand().toString() + "\r").getBytes()); DataOutput.flush(); int pause = (line.length()*8*1000)/getBaud(); sleep(pause); } else if (line.contains(readingObject .getExpected())) { System.out.println(line); textArea.append("value = " + line + "\n"); textAreaScroll.revalidate(); System.out.println("Got Value"); break; } } System.out.println("Ended"); try { inFromServer.close(); DataOutput.close(); socket.close(); isSocketRetrieving.setText("Socket is inactive..."); rs232Table.addMouseListener(listener); interrupt(); join(); } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { System.out.println("Thread exited"); } } catch (NumberFormatException e1) { e1.printStackTrace(); } catch (UnknownHostException e1) { e1.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start();

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• Running a Java program with input from a file

  - by Katy

  I am writing a program that reads the input from a file and then prints it to the screen. When I run it without taking the input from the file, it works perfectly fine. However, every time I try to run it from the file it gives me an "Exception in thread "main" java.util.NoSuchElementException: No line found at" error that occurs every place the input is suppose to be read. I have no idea what is going on.

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• Does my TPL partitioner cause a deadlock?

  - by Scott Chamberlain

  I am starting to write my first parallel applications. This partitioner will enumerate over a IDataReader pulling chunkSize records at a time from the data-source. protected class DataSourcePartitioner<object[]> : System.Collections.Concurrent.Partitioner<object[]> { private readonly System.Data.IDataReader _Input; private readonly int _ChunkSize; public DataSourcePartitioner(System.Data.IDataReader input, int chunkSize = 10000) : base() { if (chunkSize < 1) throw new ArgumentOutOfRangeException("chunkSize"); _Input = input; _ChunkSize = chunkSize; } public override bool SupportsDynamicPartitions { get { return true; } } public override IList<IEnumerator<object[]>> GetPartitions(int partitionCount) { var dynamicPartitions = GetDynamicPartitions(); var partitions = new IEnumerator<object[]>[partitionCount]; for (int i = 0; i < partitionCount; i++) { partitions[i] = dynamicPartitions.GetEnumerator(); } return partitions; } public override IEnumerable<object[]> GetDynamicPartitions() { return new ListDynamicPartitions(_Input, _ChunkSize); } private class ListDynamicPartitions : IEnumerable<object[]> { private System.Data.IDataReader _Input; int _ChunkSize; private object _ChunkLock = new object(); public ListDynamicPartitions(System.Data.IDataReader input, int chunkSize) { _Input = input; _ChunkSize = chunkSize; } public IEnumerator<object[]> GetEnumerator() { while (true) { List<object[]> chunk = new List<object[]>(_ChunkSize); lock(_Input) { for (int i = 0; i < _ChunkSize; ++i) { if (!_Input.Read()) break; var values = new object[_Input.FieldCount]; _Input.GetValues(values); chunk.Add(values); } if (chunk.Count == 0) yield break; } var chunkEnumerator = chunk.GetEnumerator(); lock(_ChunkLock) //Will this cause a deadlock? { while (chunkEnumerator.MoveNext()) { yield return chunkEnumerator.Current; } } } } IEnumerator IEnumerable.GetEnumerator() { return ((IEnumerable<object[]>)this).GetEnumerator(); } } } I wanted IEnumerable object it passed back to be thread safe (the .Net example was so I am assuming PLINQ and TPL could need it) will the lock on _ChunkLock near the bottom help provide thread safety or will it cause a deadlock? From the documentation I could not tell if the lock would be released on the yeld return. Also if there is built in functionality to .net that will do what I am trying to do I would much rather use that. And if you find any other problems with the code I would appreciate it.

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• What about the Sql transaction log

  - by Michel

  Hi, i always thought that the sql transaction log keeps track of all the transactions done in the database so it could help recovering the database file in case of a unexpected power down or something like that So then, in normal usage, when the data is committed and written to disk, it is cleared because all the data is nice and safe in the mdf file. Seeing the ldf file grow and reading some i understand that that is not the case, and it will keep growing, until: you shrink the log. Only at that point all the commited transactions are cleared and the log file is shrinked. I found some sp's who should do this, but also found the theory that you first have to backup the database? That last step doesn't make sense to me, so can anyone tell me of that is correct and if so, why that is?

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• Linq to SQL: how get row security between write access??

  - by Francisco

  I would like to allow two threads to write in a table at the same time (I know the problem of updating the same row, but this would be a story apart). I need that in behalf of speed up the operations in my aplication (one thread could write in row X while another could do the same in row X+n instead of waiting the first to finalize). So, can I block rows instead of tables with Linq to SQL? Thanks.

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• Forcing a method to be non-transactional in JPA (Eclipselink)

  - by rhinds

  Hi, I am developing an application using Eclipselink and as part of the app I need to be able to manipulate some of the objects which involves changing data without it being persisted to the database (i merging/changing objects for some batch generation processes). I am reluctant to change the data in the Entity objects, as there is a risk that even though i have not marked the methods as @Transactional, this method could in the future be inadvertantly called from within a transactional method and these changes could be persisted. So my question is, is there anyway to get around this? Such as force a method to always be non-transactional regardless; terminate any transactionality as soon as the method is started; etc. I know there is a .detach() method that can detach the objects from the Entity Manager, however, there are many objects and this seems like a potentially error prone fail-safe on my code.

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• rails large amount of data in single insert activerecord gave out

  - by Nik

  So I have I think around 36,000 just to be safe, a number I wouldn't think was too large for a modern sql database like mysql. Each record has just two attributes. So I do: so I collected them into one single insert statement sql = "INSERT INTO tasks (attrib_a, attrib_b) VALUES (c1,d1),(c2,d2),(c3,d3)...(c36000,d36000);" ActiveRecord::Base.connection.execute sql from C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract_adapter.rb:219:in `log' from C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/mysql_adapter.rb:323:in `execute_without_analyzer from c:/r/projects/vendor/plugins/rails-footnotes/lib/rails-footnotes/notes/queries_note.rb:130:in `execute' from C:/Ruby/lib/ruby/1.8/benchmark.rb:308:in `realtime' from c:/r/projects/vendor/plugins/rails-footnotes/lib/rails-footnotes/notes/queries_note.rb:130:in `execute' from (irb):53 from C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/vendor/tzinfo-0.3.12/tzinfo/time_or_datetime.rb:242 I don't know if the above info is enough, please do ask for anything that I didn't provide here. So any idea what this is about? THANK YOU!!!!

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• C: Pointers to any type?

  - by dragme

  I hear that C isn't so type-safe and I think that I could use that as an advantage for my current project. I'm designing an interpreter with the goal for the VM to be extremely fast, much faster than Ruby and Python, for example. Now I know that premature optimization "is the root of all evil" but this is rather a conceptual problem. I have to use some sort of struct to represent all values in my language (from number over string to list and map) Would the following be possible? struct Value { ValueType type; void* value; } I would store the actual values elsewhere, e.g: a separate array for strings and integers, value* would then point to some member in this table. I would always know the type of the value via the type variable, so there wouldn't be any problems with type errors. Now: Is this even possible in terms of syntax and typing?

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• Javascript: Writing a firefox extension with sockets

  - by Johnny Grass

  I need to write a firefox extension that creates a server socket (I think that's what it's called) and returns the browser's current url when a client application (running on the same computer) sends it a request. The thing is that I have no Java/Javascript background at all and I'm pressed for time so I am trying to hack something together from code samples. So far I've been mildly successful. I've been working with code from this question which is used in the open source Firefox exension PolyChrome I have the following code: var reader = { onInputStreamReady : function(input) { var input_stream = Components.classes["@mozilla.org/scriptableinputstream;1"] .createInstance(Components.interfaces.nsIScriptableInputStream); input_stream.init(input); input_stream.available(); var request = ''; while (input_stream.available()) { request = request + input_stream.read(512); } var checkString = "foo" if (request.toString() == checkString.toString()) { output_console('URL: ' + content.location.href); } else output_console("nothing"); var thread_manager = Components.classes["@mozilla.org/thread-manager;1"].getService(); input.asyncWait(reader,0,0,thread_manager.mainThread); } } var listener = { onSocketAccepted: function(serverSocket, clientSocket) { output_console("Accepted connection on "+clientSocket.host+":"+clientSocket.port); input = clientSocket.openInputStream(0, 0, 0).QueryInterface(Components.interfaces.nsIAsyncInputStream); output = clientSocket.openOutputStream(Components.interfaces.nsITransport.OPEN_BLOCKING, 0, 0); var thread_manager = Components.classes["@mozilla.org/thread-manager;1"].getService(); input.asyncWait(reader,0,0,thread_manager.mainThread); } } var serverSocket = Components.classes["@mozilla.org/network/server-socket;1"]. createInstance(Components.interfaces.nsIServerSocket); serverSocket.init(9999, true, 5); output_console("Opened socket on " + serverSocket.port); serverSocket.asyncListen(listener); I have a few questions. So far I can telnet into localhost and get a response, but my string comparison in the reader seems to fail even if I enter "foo". I don't get why. What am I missing? The sample code I'm using opens up a console window and prints output when I telnet into localhost. Ideally I would like the output to be returned as a response when the client sends a request to the server socket with a passphrase. How do I go about doing that? Is doing this a good idea? Does it create security vulnerabilities on the computer? How can I block connections to the socket from other computers? What is a good place to read about javascript sockets? My google searches have been pretty fruitless but then maybe I'm not using the right keywords.

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• Java 7 API design best practice - return Array or return Collection

  - by Shengjie

  I know this question has be asked before generic comes out. Array does win out a bit given Array enforces the return type, it's more type-safe. But now, with latest JDK 7, every time when I design this type of APIs: public String[] getElements(String type) vs public List<String> getElements(String type) I am always struggling to think of some good reasons to return A Collection over An Array or another way around. What's the best practice when it comes to the case of choosing String[] or List as the API's return type? Or it's courses for horses. I don't have a special case in my mind, I am more looking for a generic pros/cons comparison.

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• Multithreading, when to yield versus sleep

  - by aaa

  hello. To clarify terminology, yield is when thread gives up its time slice. My platform of interest is POSIX threads, but I think question is general. Suppose I have consumer/producer pattern. If I want to throttle either consumer or producer, which is better to use, sleep or yield? I am mostly interested in efficiency of using either function. Thanks

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