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  • C#, Can I check on a lock without trying to acquire it?

    - by Biff MaGriff
    Hello, I have a lock in my c# web app that prevents users from running the update script once it has started. I was thinking I would put a notification in my master page to let the user know that the data isn't all there yet. Currently I do my locking like so. protected void butRefreshData_Click(object sender, EventArgs e) { Thread t = new Thread(new ParameterizedThreadStart(UpdateDatabase)); t.Start(this); //sleep for a bit to ensure that javascript has a chance to get rendered Thread.Sleep(100); } public static void UpdateDatabase(object con) { if (Monitor.TryEnter(myLock)) { Updater.RepopulateDatabase(); Monitor.Exit(myLock); } else { Common.RegisterStartupScript(con, AlreadyLockedJavaScript); } } And I do not want to do if(Monitor.TryEnter(myLock)) Monitor.Exit(myLock); else //show processing labal As I imagine there is a slight possibility that it might display the notification when it isn't actually running. Is there an alternative I can use? Edit: Hi Everyone, thanks a lot for your suggestions! Unfortunately I couldn't quite get them to work... However I combined the ideas on 2 answers and came up with my own solution.

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  • android: consume key press, bypassing framework processing

    - by user360024
    What I want android to do: when user presses a single key, have the view respond, but do so without opening a text area and displaying the character associated with the key that was pressed, and without requiring that the Enter key be pressed, and without requiring that the user press Esc to make the text area go away. For example, when user presses "u" (and doesn't press Enter), that means "undo the last action", so the controller and model immediately undo the last action, then the view does an invalidate() and user sees that their last action has been undone. In other words the "u" key press should be silently processed, such that the only visual result is that user's last action has been undone. I've implemented OnKeyListener and provided an onKey() method: the class: public class MyGameView extends View implements OnKeyListener{ in the constructor: //2010jun06, phj: With onKey(), helps let this View consume key presses // before the framework gets a chance to consume the key press. setOnKeyListener((View.OnKeyListener)this); the onKey() method: public boolean onKey(View v, int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_R) { Log.d("BWA", "In onKey received keycode associated with R."); } return true; // meaning the event (key press) has been consumed, so // the framework should not handle this event. } but when user presses "u" key on the emulator keypad, a textarea is opened at the bottom of the screen, the "u" charater is displayed there, and the onKey() method doesn't execute until user presses the Enter key. Is there a way to make android do what I want? Thanks,

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  • MSI install sequence - run DB scripts before services start

    - by marc_s
    Folks, we're running into some sequencing troubles with our MSI install. As part of our app, we install a bunch of services and allow the user to pick whether to start them right away or later. When they start right away, they seem to start too early in the install sequence - before our database manager had a chance to update the database. Right now, our custom action to run the database updater looks like this - it's being run after "InstallFinalize" - very late in the process. <InstallExecuteSequence> <RemoveExistingProducts After='InstallInitialize' /> <Custom Action='RunDbUpdateManagerAction' After='InstallFinalize'> DbUpdateManager=3</Custom> </InstallExecuteSequence> What would be the more appropriate step to run after or before, to make sure the DB scripts are executed before any of the installed services start up? Is there a "BeforeServiceStart" step? EDIT: Just defining the "Before='StartServices'" attribute on the tag didn't solve my problem. I am assuming the issue is this: the custom action has an "inner text", which represents a condition, and this condition is: "&DbUpdateManager=3". From what I can deduce from trial & error, this probably means "the DbUpdateManager feature must be published". Now, trouble is: "PublishFeature" comes way at the end in the install sequence, just before "InstallFinalize", and definitely AFTER InstallServices / StartServices. So when I specify the "Before=StartServices" requirement, the condition "DbUpdateManager feature must be published" isn't true yet, so the DbUpdateManager doesn't get executed :-( I tried removing the condition - in that case, my DbUpdateManager sometimes doesn't execute at all, sometimes more than once - no real clear pattern as to what happens when..... Any more ideas?? Is there a way I could check for a condition "the DbUpdateManager feature is installed" which would be true after the "InstallFiles" step?? Marc

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  • Accurately and securely measure the time spent viewing a web page

    - by balpha
    Suppose the following: You have a web page that presents a simple game to a user (e.g. a quiz, a puzzle, etc). The user solves the puzzle, submits the result, and you want to measure as precisely as possible how long they took to solve it. Assume it's quite simple, so we're talking seconds, not hours. Also assume JavaScript is required anyway, so there's no need to think of JS-disabled browsers. Finally, assume we don't want to use anything like Flash, Silverlight, or the like. I can think of several techniques: Simply take the time between the points when the data was sent from the server and when the submission arrives. Since this is exclusively server-side, there's no chance for cheating. However, issues like network latency and page rendering time might make this unfair for users with slow computers / browsers / internet connections. On the first request, just send the page without the actual game data. When everything is loaded so far, retrieve the game data through an AJAX call and populate it into the page. This is similar to 1., but reduces some of the caveats introduced through time spent on overhead. Have the time measured on the client side using JavaScript and submitted alongside with the solution. This would theoretically be the most accurate, but it introduces the possibility of cheating, because you're relying on client data. Use the request time headers of a "ready to play" AJAX call and the result submission request. Same caveat as 3., as it is still client data. A combination of server side and client side measuring with some kind of plausibility analysis. I can't think of a good way, but maybe you can. Thoughts? Other ideas?

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  • How to decide between using PLINQ and LINQ at runtime?

    - by Hamish Grubijan
    Or decide between a parallel and a sequential operation in general. It is hard to know without testing whether parallel or sequential implementation is best due to overhead. Obviously it will take some time to train "the decider" which method to use. I would say that this method cannot be perfect, so it is probabilistic in nature. The x,y,z do influence "the decider". I think a very naive implementation would be to give both 1/2 chance at the beginning and then start favoring them according to past performance. This disregards x,y,z, however. I suspect that this question would be better answered by academics than practitioners. Anyhow, please share your heuristic, your experience if any, your tips on this. Sample code: public interface IComputer { decimal Compute(decimal x, decimal y, decimal z); } public class SequentialComputer : IComputer { public decimal Compute( ... // sequential implementation } public class ParallelComputer : IComputer { public decimal Compute( ... // parallel implementation } public class HybridComputer : IComputer { private SequentialComputer sc; private ParallelComputer pc; private TheDecider td; // Helps to decide between the two. public HybridComputer() { sc = new SequentialComputer(); pc = new ParallelComputer(); td = TheDecider(); } public decimal Compute(decimal x, decimal y, decimal z) { decimal result; decimal time; if (td.PickOneOfTwo() == 0) { // Time this and save result into time. result = sc.Compute(...); } else { // Time this and save result into time. result = pc.Compute(); } td.Train(time); return result; } }

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  • ASP.NET Web Application: use 1 or multiple virtual directories

    - by tster
    I am working on a (largish) internal web application which has multiple modules (security, execution, features, reports, etc.). All the pages in the app share navigation, CSS, JS, controls, etc. I want to make a single "Web Application" project, which includes all the pages for the app, then references various projects which will have the database and business logic in them. However, some of the people on the project want to have separate projects for the pages of each module. To make this more clear, this is what I'm advocating to be the projects. /WebInterface* /SecurityLib /ExecutionLib etc... And here is what they are advocating: /SecurityInterface* /SecutiryLib /ExecutionInterface* /ExecutionLib etc... *project will be published to a virtual directory of IIS Basically What I'm looking for is the advantages of both approaches. Here is what I can think of so far: Single Virtual Directory Pros Modules can share a single MasterPage Modules can share UserControls (this will be common) Links to other modules are within the same Virtual directory, and thus don't need to be fully qualified. Less chance of having incompatible module versions together. Multiple Virtual Directories Pros Can publish a new version of a single module without disrupting other modules Module is more compartmentalized. Less likely that changes will break other modules. I don't buy those arguments though. First, using load balanced servers (which we will have) we should be able to publish new versions of the project with zero downtime assuming there are no breaking database changes. Second, If something "breaks" another module, then there is either an improper dependency or the break will show up eventually in the other module, when the developers copy over the latest version of the UserControl, MasterPage or dll. As a point of reference, there are about 10 developers on the project for about 50% of their time. The initial development will be about 9 months.

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  • Why does Firefox + My code Destroys FireFox refresh

    - by acidzombie24
    I am soo angry right now. I lost hours and i dont know why this happens. Its a semi rant but i'll try to keep it short My code would not work, even after refreshing it was broken I fixed my code or so i thought because it stops working without me changing anything (you would think i am imagining this...) I somehow decide to make a new window or tab i run my code and verifies it works. I write more code and see everything is broken again I write test in a new window and see my code does work I see my code doesnt work and firebug DOES NOT HELP I notice when i create a new tab everything works I realize refreshing does not work and i MUST make a new tab for my code to work. Then i knew instantly what the problem was. I modify a display:none textbox but i set the values incorrectly. I cant see it because it is hidden. Now some of you might say its my fault because when doing a refresh all of the data may be cache. But here is the kicker. I was using POST data. I posted in between of the refresh each and everytime. Whats the point of using POST when the same data is cached and use anyways? If theres no chance for a search engine to follow a block user get link then why should i bother making anything post when security or repeat actions are not an issue? POST didnt seem to do anything.

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  • ASP.NET server data persistence

    - by Wayne Werner
    Hi, I'm not really sure exactly how the question should be phrased, so please be patient if I ask the wrong thing. I'm writing an ASP.NET application using VB as the code behind language. I have a data access class that connects to the DB to run the query (parameterized, of course), and another class to perform the validation tasks - I access this class from my aspx page. What I would like is to be able to store the data server side and wait for the user to choose from a few options based on the validity of the data. But unless my understanding is completely off, having persistent data objects on the server will give problems when multiple users connect? My ultimate goal is that once the data has been validated the end user can't modify it. Currently I'm validating the data, but I still have to retrieve it from the web form AFTER the user says OK, which obviously leaves open the possibility of injecting bad data either accidentally (unlikely) or on purpose (also unlikely for the use, but I'd prefer not to take the chance). So am I completely off in my understanding? If so, can someone point me to a resource that provides some instructions on keeping persistent data on the server, or provide instruction? Thanks!

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  • Searching For A Record After A LINQ query

    - by Justin
    I'm confused to why this is happening. I'm new to LINQ so I'm clearly missing something here, that is probably pretty easy. I've looked up help on the topic, but I don't really know what to ask so I haven't found any answers that really address my question. This doesn't work It throws an EntityCommandExecutionException when the FirstOrDefault method is executed. var query = from band in context.BandsEntitySet where band.ID == 12345 select band; string venueName = "Willis Park"; foreach (var item in query) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } This works var query = from band in context.BandsEntitySet where band.ID == 12345 select band; var bandList = query.toList(); string venueName = "Willis Park"; foreach (var item in bandList) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } My question is simple: Why is the exception being thrown? And why does creating a list from the query allow me to use the FirstOrDefault method? Exception Message: A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll I guess I am wrong in my assumption that query is a list? Then what is it exactly? I'm confused because this doesn't throw an exception: foreach (var item in query) { var area = item.VenueArea; } I'd appreciate any help on this issue. thanks, Justin

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  • Chinese Characters in email sent via PHP not showing up.

    - by rye
    hi All, a funny problem. I send mail via PHP from my testing server with Chinese chars in it and it sends perfectly. Encoding is utf-8. When I upload the same PHP file to another server and try to send from there, the e-mail will look 90% fine in one mail client (web-based mail actually, gmail), but in my mail client (Apple Mail) it's all gibberish even when I try changing the encoding in the mail client. I'm stuck here because everything works fine on one server, but not on another so I'm not sure where to start looking for solutions. What's even more puzzling is that on the production server, the mail looks somewhat ok (strange case of some characters not showing) but in other mail apps it looks like garbage. any idea where I can start looking to solve this? thanks for any help here! Regards.. php script $books = json_decode ($_POST['books']); $body = ' ?? ' . $_POST['name'] . ',?????????,????????,???????? '; $iLen = count($books); for ($i = 0; $i ' . $book-title . '' . $book-author . ''; $body .= '??: ' . $book-synopsis . ''; $body .= '???: ' . $book-age . ''; $body .= '??: ' . $book-setting . ''; $body .= '??: ' . $book-purpose . ''; $body .= '???: ' . $book-call . ''; $body .= '???: ' . $book-publisher . ''; } $body .= ' ????,Name '; $headers = 'MIME-Version: 1.0' . "\r\n"; $headers .= 'Content-type: text/html; charset=utf-8' . "\r\n"; $headers .= 'From: Name ' . "\r\n"; $ok = mail ($_POST['email'], '???????:???????????', $body, $headers); result ä? å¥? ryan, 以丗æ?¯ä? ä»/å–œä’ ç?Œç«?,ç»?å–©å–?è®”æ??亗è¯=稗,昕蜙æ±?ç°=䒜籟å?ŸåŸ? ç‘?ç‘?ævŒæ?˜å¤°çv±ä? 麜å?—å¸8é?·å°p, å±±å§? Synopsis: ç?—å?¯çv±ç°=å°?å?‰å®?å®?æ•/ä’v牨å®8痬瘒ç°=戒åp?å‚‘å?‰åœvåœv说å®8æ?˜å¤°çv±å®8ã•? Age Group: 4 - 6 å”™ Setting: ç=¤ä?„ Purpose: ä»·å•pè§?å‚‘ä¿8è¿?五å–?ç°=æ=ƒæ8? Call no: JP MAC Publisher: 麜å?—å¸8é?·å°p, å±±å§?. ç‘?ç‘?ævŒæ?˜å¤°çv±ä? .丅海 : 尌咴å=¿ç«¥åOºç˜vç¤=, 2005.

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  • Running processes at different times stops events from working - C

    - by Jamie Keeling
    Hello, This is a question which follows on from my previously answered question here At first I assumed I had a problem with the way I was creating my events due to the handles for OpenEvent returning NULL, I have managed to find the real cause however I am not sure how to go about it. Basically I use Visual Studio to launch both Process A and B at the same time, in the past my OpenEvent handle wouldn't work due to Process A looking for the address of the event a fraction of a second before Process B had time to make it. My solution was to simply allow Process B to run before Process A, fixing the error. The problem I have now is that Process B now reads events from Process A and as you expect it too returns a null handle when trying to open the events from Process A. I am creating the events in WM_CREATE message of both processes, furthermore I also create a thread at the same time to open/read/act upon the events. It seems if I run them at the same time they don't get chance to see each other, alternatively if I run one before the other one of them misses out and can't open a Handle. Can anyone suggest a solution? Thanks.

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  • Reduce durability in MySQL for performance

    - by Paul Prescod
    My site occasionally has fairly predictable bursts of traffic that increase the throughput by 100 times more than normal. For example, we are going to be featured on a television show, and I expect in the hour after the show, I'll get more than 100 times more traffic than normal. My understanding is that MySQL (InnoDB) generally keeps my data in a bunch of different places: RAM Buffers commitlog binary log actual tables All of the above places on my DB slave This is too much "durability" given that I'm on an EC2 node and most of the stuff goes across the same network pipe (file systems are network attached). Plus the drives are just slow. The data is not high value and I'd rather take a small chance of a few minutes of data loss rather than have a high probability of an outage when the crowd arrives. During these traffic bursts I would like to do all of that I/O only if I can afford it. I'd like to just keep as much in RAM as possible (I have a fair chunk of RAM compared to the data size that would be touched over an hour). If buffers get scarce, or the I/O channel is not too overloaded, then sure, I'd like things to go to the commitlog or binary log to be sent to the slave. If, and only if, the I/O channel is not overloaded, I'd like to write back to the actual tables. In other words, I'd like MySQL/InnoDB to use a "write back" cache algorithm rather than a "write through" cache algorithm. Can I convince it to do that? If this is not possible, I am interested in general MySQL write-performance optimization tips. Most of the docs are about optimizing read performance, but when I get a crowd of users, I am creating accounts for all of them, so that's a write-heavy workload.

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  • How do I implement a group of strings that starts randomly, but is bound by relevance upon selection?

    - by Freakishly
    Okay the title may be a little confusing, but here's what I'm trying to do :) I have a game in XNA where every tap from the user draws a moving circle on the screen. The circle has a tag, say 'dogs' displayed on it. So imagine multiple taps on the screen, and we have all these circles of various colors and sizes moving around the screen with different (but constant) velocities. Each circle with different tags: 'dogs', 'cats' and so on... Clicking on empty space generates a new circle at that point. Clicking on one of the circles "selects" it, turning it into a greeen shade and slowing its velocity down to a fraction of what it was. Clicking on it again "unselects" it, and restores its original color and velocity (trajectory does not change). With each circle comes a tag, and as of now I'm populating these tags randomly from a string array (which means there's a chance tags will repeat). I would like the tags for newly created circles to be relevant to previous "selected" tags. So when I click on 'dogs', I would like 'German Shepherd' but I would also like 'dog parks' and 'lemurs' assuming dogs get along well with lemurs. What would be the best way to approach this problem. In my head I have a massive many-to-many mapping, but I can't seem to translate it to code. Thanks for looking. FYI I'm using the sample project from here: http://mobile.tutsplus.com/tutorials/windows/introduction-to-xna-on-windows-phone-7/

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  • How would you organize this in asp.net mvc?

    - by chobo
    I have an asp.net mvc 2.0 application that contains Areas/Modules like calendar, admin, etc... There may be cases where more than one area needs to access the same Repo, so I am not sure where to put the Data Access Layers and Repositories. First Option: Should I create Data Access Layer files (Linq to SQL in my case) with their accompanying Repositories for each area, so each area only contains the Tables, and Repositories needed by those areas. The benefit is that everything needed to run that module is one place, so it is more encapsulated (in my mind anyway). The downside is that I may have duplicate queries, because other modules may use the same query. Second Option Or, would it be better to place the DAL and Repositories outside the Area's and treat them as Global? The advantage is I won't have any duplicate queries, but I may be loading a lot of unnecessary queries and DAL tables up for certain modules. It is also more work to reuse or modify these modules for future projects (though the chance of reusing them is slim to none :)) Which option makes more sense? If someone has a better way I'd love to hear it. Thanks!

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  • I'm graduating with a Computer Science degree but I don't feel like I know how to program.

    - by Wendy Peters
    I'm graduating with a Computer Science degree but I see websites like Stackoverflow and search engines like Google and don't know where I'd even begin to write something like that. During one summer I worked as a iPhone developer, but I felt like I was mostly gluing together libraries that other people had written with little understanding of what's happening underneath the hood. I'm trying to improve my knowledge by studying algorithms, but it is a long and painful process. I find algorithms difficult and at the rate I am working through my book it will a decade will have passed before I will finish. Given my current situation, I've spent a month looking for work but my skills (C, Python, Objective-C) are not so desirable in the local market, where C#, Java, and web development are much higher in demand. My GPA is ok (3.0) but it's not high enough to apply to the large companies or return for graduate studies and I don't have a good network of friends. Basically I'm graduating with a Computer Science degree but I don't feel like I know how to program. I thought that joining a company and programming full-time would give me a chance to develop my skills and learn from those more experienced than myself, but I'm struggling to find work and am starting to get really frustrated. I am going to cast my net wider and look beyond the city I've grown up in, but what have other people in similar situation tried to do?

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  • How long is the time frame between context switches on Windows?

    - by mattcodes
    Reading CLR via C# 2.0 (I dont have 3.0 with me at the moment) Is this still the case: If there is only one CPU in a computer, only one thread can run at any one time. Windows has to keep track of the thread objects, and every so often, Windows has to decide which thread to schedule next to go to the CPU. This is additional code that has to execute once every 20 milliseconds or so. When Windows makes a CPU stop executing one thread's code and start executing another thread's code, we call this a context switch. A context switch is fairly expensive because the operating system has to: So circa CLR via C# 2.0 lets say we are on Pentium 4 2.4ghz 1 core non-HT, XP. Every 20 milliseconds? Where a CLR thread or Java thread is mapped to an OS thread only a maximum of 50 threads per second may get a chance to to run? I've read that context switching is very fast in mircoseconds here on SO, but how often roughly (magnitude style guesses) will say a modest 5 year old server Windows 2003 Pentium Xeon single core give the OS the opportunity to context switch? 20ms in the right area? I dont need exact figures I just want to be sure that's in the right area, seems rather long to me.

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  • "Detecting" and loading of "plugins" in GAE

    - by Patrick Cornelissen
    Hi! I have a "plugin like" architecture and I want to create one instance of each class that implements a dedicated interface and put these in a cache. (To have a singleton-ish effect). The plugins will be provided as jars and put into the app engine war file before the app is uploaded. I have tried to use the ClassPathScanningCandidateComponentProvider as I'm using spring anyway, but this didn't work. The provider complained that it was not able to find the HttpServletResponse class file while scanning the classpath. I can't get around this, when I add the servlet jar, then I'll get of course problems, because the same jar is also provided by the GAE. If I don't, I'm getting the error above... So I tried to add a static initialization code, but of course this doesn't work, because the class is initialized when it's instantiated for the first time. (Well I knew that but it was worth a try) The last chance I currently see is that I create a properties file with all plugin classes when the package is created, but this requires writing of a maven plugin etc. and I'd like to avoid that. Is there something that I am missing?

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  • Getting moved out of a development job

    - by Jay
    I'm a year out of college and I started my first dev job at a small (<15 people) company several months ago. It was an internship position that recently turned full time. The position started out as development but for full time I got offered a grab bag of positions: qa, docs, call support and some dev work. It's clear that my employers feel I am lacking dev skills, which is true. I did not major in CS in college and did not have much dev experience. However, I'm convinced that I can be a good developer and I will be a good developer once given the chance to write lots of code. My question is simple: what should I do? As I see it, there are two options. Work hard in the non-dev duties so that my employers may eventually give me significant dev responsibilities. Look for a new job where I will be a developer first and an all purpose guy second (if at all). Thanks guys.

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  • Have Microsoft changed how ASP.NET MVC deals with duplicate action method names?

    - by Jason Evans
    I might be missing something here, but in ASP.NET MVC 4, I can't get the following to work. Given the following controller: public class HomeController : Controller { public ActionResult Index() { return View(); } [HttpPost] public ActionResult Index(string order1, string order2) { return null; } } and it's view: @{ ViewBag.Title = "Home"; } @using (Html.BeginForm()) { @Html.TextBox("order1")<br /> @Html.TextBox("order2") <input type="submit" value="Save"/> } When start the app, all I get is this: The current request for action 'Index' on controller type 'HomeController' is ambiguous between the following action methods: System.Web.Mvc.ActionResult Index() on type ViewData.Controllers.HomeController System.Web.Mvc.ActionResult Index(System.String, System.String) on type ViewData.Controllers.HomeController Now, in ASP.NET MVC 3 the above works fine, I just tried it, so what's changed in ASP.NET MVC 4 to break this? OK there could be a chance that I'm doing something silly here, and not noticing it. EDIT: I notice that in the MVC 4 app, the Global.asax.cs file did not contain this: public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults ); } which the MVC 3 app does, by default. So I added the above to the MVC 4 app but it fails with the same error. Note that the MVC 3 app does work fine with the above route. I'm passing the "order" data via the Request.Form. EDIT: In the file RouteConfig.cs I can see RegisterRoutes is executed, with the following default route: routes.MapRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }); I still get the original error, regards ambiguity between which Index() method to call.

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  • Callers block until getFoo() has a value ready?

    - by Sean Owen
    I have a Java Thread which exposes a property which other threads want to access: class MyThread extends Thread { private Foo foo; ... Foo getFoo() { return foo; } ... public void run() { ... foo = makeTheFoo(); ... } } The problem is that it takes some short time from the time this runs until foo is available. Callers may call getFoo() before this and get a null. I'd rather they simply block, wait, and get the value once initialization has occurred. (foo is never changed afterwards.) It will be a matter of milliseconds until it's ready, so I'm comfortable with this approach. Now, I can make this happen with wait() and notifyAll() and there's a 95% chance I'll do it right. But I'm wondering how you all would do it; is there a primitive in java.util.concurrent that would do this, that I've missed? Or, how would you structure it? Yes, make foo volatile. Yes, synchronize on an internal lock Object and put the check in a while loop until it's not null. Am I missing anything?

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  • How can I programmatically position a view using relative points?

    - by Steve Madsen
    What is the best way to position a view relative to the size of its superview, when the bounds of the superview are not yet known? I am trying to avoid hard-coding coordinates if it is at all possible. Perhaps this is silly, and if so, that's a perfectly acceptable answer. I've run into this many times when working with custom UI. The most recent example is that I'm trying to replace the UINavigationItem plain-text title with a custom view. I want that view to fill the superview, but in addition, I want a UIActivityIndicatorView on the right side, inset about 2 pixels and centered vertically. Here's the code: - (void) viewDidLoad { [super viewDidLoad]; customTitleView = [[UIView alloc] initWithFrame:CGRectZero]; customTitleView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; titleLabel = [[UILabel alloc] initWithFrame:CGRectZero]; titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; titleLabel.lineBreakMode = UILineBreakModeWordWrap; titleLabel.numberOfLines = 2; titleLabel.minimumFontSize = 11.0; titleLabel.font = [UIFont systemFontOfSize:17.0]; titleLabel.adjustsFontSizeToFitWidth = YES; [customTitleView addSubview:titleLabel]; spinnerView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]; spinnerView.center = CGPointMake(customTitleView.bounds.size.width - (spinnerView.bounds.size.width / 2) - 2, customTitleView.bounds.size.height / 2); spinnerView.hidesWhenStopped = YES; [customTitleView addSubview:spinnerView]; self.navigationItem.titleView = customTitleView; [customTitleView release]; } Here's my problem: at the time that this code runs, customTitleView.bounds is still zeroes. The auto-resizing mask hasn't had a chance to do its thing yet, but I very much want those values so that I can compute the relative positions of other sub-views (here, the activity indicator). Is this possible without being ugly?

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  • Advice: Python Framework Server/Worker Queue management (not Website)

    - by Muppet Geoff
    I am looking for some advice/opinions of which Python Framework to use in an implementation of multiple 'Worker' PCs co-ordinated from a central Queue Manager. For completeness, the 'Worker' PCs will be running Audio Conversion routines (which I do not need advice on, and have standalone code that works). The Audio conversion takes a long time, and I need to co-ordinate an arbitrary number of the 'Workers' from a central location, handing them conversion tasks (such as where to get the source files, or where to ask for the job configuration) with them reporting back some additional info, such as the runtime of the converted audio etc. At present, I have a script that makes a webservice call to get the 'configuration' for a conversion task, based on source files located on the worker already (we manually copy the source files to the worker, and that triggers a conversion routine). I want to change this, so that we can distribute conversion tasks ("Oy you, process this: xxx") based on availability, and in an ideal world, based on pending tasks too. There is a chance that Workers can go offline mid-conversion (but this is not likely). All the workers are Windows based, the co-ordinator can be WIndows or Linux. I have (in my initial searches) come across the following - and I know that some are cross-dependent: Celery (with RabbitMQ) Twisted Django Using a framework, rather than home-brewing, seems to make more sense to me right now. I have a limited timeframe in which to develop this functional extension. An additional consideration would be using a Framework that is compatible with PyQT/PySide so that I can write a simple UI to display Queue status etc. I appreciate that the specifics above are a little vague, and I hope that someone can offer me a pointer or two. Again: I am looking for general advice on which Python framework to investigate further, for developing a Server/Worker 'Queue management' solution, for non-web activities (this is why DJango didn't seem the right fit).

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  • Avoid slowdowns while using off-site database

    - by Anders Holmström
    The basic layout of my problem is this: Website (ASP.NET/C#) hosted at a dedicated hosting company (location 1) Company database (SQL Server) with records of relevant data (location 2). Location 1 & 2 connected through VPN. Customer visiting the website and wanting to pull data from the company database. No possibility of changing the server locations or layout (i.e. moving the website to an in-office server isn't possible). What I want to do is figure out the best way to handle the data acces in this case, minimizing the need for time-expensive database calls over the VPN. The first idea I'm getting is this: When a user enters the section of the website needing the DB data, you pull all the needed tables from the database into a in-memory dataset. All subsequent views/updates to the data is done on this dataset. When the user leaves (logout, session timeout, browser closed etc) the dataset gets sent to the SQL server. I'm not sure if this is a realistic solution, and it obviously has some problems. If two web visitors are performing updates on the same data, the one finishing up last will have their changes overwriting the first ones. There's also no way of knowing you have the latest data (i.e. if a customer pulls som info on their projects and we update this info while they are viewing them, they won't see these changes PLUS the above overwriting issue will arise). The other solution would be to somehow aggregate database calls and make sure they only happen when you need them, e.g. during data updates but not during data views. But then again the longer a pause between these refreshing DB calls, the bigger a chance that the data view is out of date as per the problem described above. Any input on the above or some fresh ideas would be most welcome.

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  • C++ Optimize if/else condition

    - by Heye
    I have a single line of code, that consumes 25% - 30% of the runtime of my application. It is a less-than comparator for an std::set (the set is implemented with a Red-Black-Tree). It is called about 180 Million times within 52 seconds. struct Entry { const float _cost; const long _id; // some other vars Entry(float cost, float id) : _cost(cost), _id(id) { } }; template<class T> struct lt_entry: public binary_function <T, T, bool> { bool operator()(const T &l, const T &r) const { // Most readable shape if(l._cost != r._cost) { return r._cost < l._cost; } else { return l._id < r._id; } } }; The entries should be sorted by cost and if the cost is the same by their id. I have many insertions for each extraction of the minimum. I thought about using Fibonacci-Heaps, but I have been told that they are theoretically nice, but suffer from high constants and are pretty complicated to implement. And since insert is in O(log(n)) the runtime increase is nearly constant with large n. So I think its okay to stick to the set. To improve performance I tried to express it in different shapes: return l._cost < r._cost || r._cost > l._cost || l._id < r._id; return l._cost < r._cost || (l._cost == r._cost && l._id < r._id); Even this: typedef union { float _f; int _i; } flint; //... flint diff; diff._f = (l._cost - r._cost); return (diff._i && diff._i >> 31) || l._id < r._id; But the compiler seems to be smart enough already, because I haven't been able to improve the runtime. I also thought about SSE but this problem is really not very applicable for SSE... The assembly looks somewhat like this: movss (%rbx),%xmm1 mov $0x1,%r8d movss 0x20(%rdx),%xmm0 ucomiss %xmm1,%xmm0 ja 0x410600 <_ZNSt8_Rb_tree[..]+96> ucomiss %xmm0,%xmm1 jp 0x4105fd <_ZNSt8_Rb_[..]_+93> jne 0x4105fd <_ZNSt8_Rb_[..]_+93> mov 0x28(%rdx),%rax cmp %rax,0x8(%rbx) jb 0x410600 <_ZNSt8_Rb_[..]_+96> xor %r8d,%r8d I have a very tiny bit experience with assembly language, but not really much. I thought it would be the best (only?) point to squeeze out some performance, but is it really worth the effort? Can you see any shortcuts that could save some cycles? The platform the code will run on is an ubuntu 12 with gcc 4.6 (-stl=c++0x) on a many-core intel machine. Only libraries available are boost, openmp and tbb. I am really stuck on this one, it seems so simple, but takes that much time. I have been crunching my head since days thinking how I could improve this line... Can you give me a suggestion how to improve this part, or is it already at its best?

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  • queued view updates not happening when performSelector afterDelay:0 used

    - by JosephH
    Hi all, I have an app that performs some calculations based on data arriving on a socket or local user interaction. I want to show an 'activity spinner' whilst the calculation happens. spinner = [[UIActivityIndiactorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; [spinner setCenter:self.view.center]; [self.view addSubview:spinner]; [spinner startAnimating]; [self performSelector:@selector(doCalcs) withObject:nil afterDelay:0]; This works well, except in the case where the code is run as a result of a message arriving over the network. I'm using http://code.google.com/p/cocoaasyncsocket/ to handle sockets and the code is running in the onSocket:didReadData:withTag: method. 'doCalcs' takes a few seconds. The spinner doesn't appear whilst it's running. If I change afterDelay:0 to afterDelay:1 then the spinner does appear the whole time doCalcs is running, but with the downside that it takes an extra second. So it seems the code is all correct, but for whatever reason the spinner isn't getting a chance to get on screen before doCalcs runs. Any suggestions would be most welcome.

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