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  • How can I make permanent death in a MUD seem acceptable and fair to players?

    - by Luke Laupheimer
    I have considered writing a MUD for years, and I have a lot of ideas my friends think are really cool (and that's how I'd hope to get anywhere -- word of mouth). Thing is, there's one thing I have always wanted, that my friends and strangers hated: permanent death. Now, the emotional response I get to this is visceral revulsion, every time. I'm pretty sure I am the only person that wants this, or if I'm not, I'm a tiny minority. Now, the reason I want it is because I want the actions of the players to matter. Unlike a lot of other MUDs, which have a set of static city-states and social institutions etc, I want the things my players do, should I get any, to actually change the situation. And that includes killing people. If you kill someone, you didn't send them to time out, you killed them. What happens when you kill people? They go away. They don't come back in half an hour to smack talk you some more. They're gone. Forever. By making death non-permanent, you make death not matter. It would be similar if a climax to a character's arc is getting a speeding ticket. It cheapens it. Non-permanent death cheapens death. How can I: 1) Convince my players (and random people!) that this is actually a good idea?, or 2) Find some other way to make death and violence matter as much as it does in real life (except within the game, of course) sans character deletion? What alternatives are there out there?

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  • Iphone build error - literal-pointer symbol(s) not found

    - by Nick
    Sorry I imagine I'm missing something basic here. Before I write up a bunch of details on the specifics of the class I'd appreciate a nudge or smack on the head about the meaning of this build error. I have a subclass of NSObject SiteAnnotation that should be conforming to the MKAnnotation protocol. It is #imported in the ViewController in question When I try to alloc/init: SiteAnnotation *thisAnnotation = [[SiteAnnotation alloc] init]; This is the build error which occurs: Link /build/Debug-iphonesimulator/testbed.app/testbed ".objc_class_name_SiteAnnotation", referenced from: literal-pointer@__OBJC@__cls_refs@SiteAnnotation in MapViewController.o Symbol(s) not found collect2: ld returned 1 exit status Any tips appreciated.

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  • gcc returns error with nested class

    - by Nate
    Howdy, I am attempting to use the fully qualified name of my nested class as below, but the compiler is balking! template <class T> class Apple { //constructors, members, whatevers, etc... public: class Banana { public: Banana() { //etc... } //other constructors, members, etc... }; }; template <class K> class Carrot{ public: //etc... void problemFunction() { Apple<int>::Banana freshBanana = someVar.returnsABanana(); //line 85 giveMonkey(freshBanana); //line 86 } }; My issue is, the compiler says: Carrot.h:85: error: expected ';' before 'freshBanana' Carrot.h:86: error: 'freshBanana' was not declared in this scope I had thought that using the fully qualified name permitted me to access this nested class? It's probably going to smack me in the face, but what on earth am I not seeing here??

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  • How to configure XMPP to allow all logged in user to see each other and chat with each other?

    - by Nachiket
    Hello guys, I am new to XMPP. I am using Openfire server, and created a console client using Smack library. My usecase: All users anonymous, logged in (In future, website visitors) will be able to see other anonymous, logged-in users. And they can initiate a private chat (one-to-one) with any of them. So, I am able to logged in as Anonymous user, but I am not able to see other Anon / Logged in users (using Roster), because they are not in anon user's roster. So, What should be configuration OR custom=component/code to to achieve this usecase? Do I need to create server component? Any hint? OR It can be done using proper configuration? Cheers

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  • Yammer, Berkeley DB, and the 3rd Platform

    - by Eric Jensen
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:major-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:major-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:major-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:major-bidi; mso-bidi-language:EN-US;} If you read the news, you know that the latest high-profile social media acquisition was just confirmed. Microsoft has agreed to acquire Yammer for 1.2 billion. Personally, I believe that Yammer’s amazing success can be mainly attributed to their wise decision to use Berkeley DB Java Edition as their backend data store. :-) I’m only kidding, of course. However, as Ryan Kennedy points out in the video I recently blogged about, BDB JE did provide the right feature set that allowed them to reliably grow their business. Which in turn allowed them to focus on their core value add. As it turns out, their ‘add’ is quite valuable! This actually makes sense to me, a lot more sense than certain other recent social acquisitions, and here’s why. Last year, IDC declared that we are entering a new computing era, the era of the “3rd Platform.” In case you’re curious, the first 2 were terminal computing and client/server computing, IIRC. Anyway, this 3rd one is more complicated. This year, IDC refined the concept further. It now involves 4 distinct buzzwords: cloud, social, mobile, and big data. Yammer is a social media platform that runs in the cloud, designed to be used from mobile devices. Their approach, using Berkeley DB Java Edition with High Availability, qualifies as big data. This means that Yammer is sitting right smack in the center if IDC’s new computing era. Another way to put it is: the folks at Yammer were prescient enough to predict where things were headed, and get there first. They chose Berkeley DB to handle their data. Maybe you should too!

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  • NHibernate.MappingException (no persister for) weirdness

    - by Berryl
    The weird part being that I have other tests that validate the mapping and even the method being called (Nhib session.SaveOrUpdate) that run just fine. The entire exception is below. Here is some debug output from a test that does work: Item type: Domain.Model.Projects.Project item: 007-00-056 ATM Machine Replacement Is transient: True Id: 0 NHibernate: INSERT INTO Projects (Code, Description) VALUES (@p0, @p1); select insert_rowid();@p0 = '007-00-056', @p1 = 'ATM Machine Replacement' Here is the same debug output before the exception: Item type: Smack.ConstructionAdmin.Domain.Model.Projects.Project item: 006-00-023 Refinish Casino Chairs Is transient: True Id: 0 The two tests are different in that the one that works is just testing the repository, and saving in memory test data. The failing one is saving data that has been converted from a legacy db (which has it's own session). The repository is also a replacement design for a different IProjectRepsitory that worked fine doing this, so the new repository is also a likely suspect here. Does anyone see what I'm missing or have some questions to narrow it down? Cheers, Berryl === the Exception trace ===== failed: NHibernate.MappingException : No persister for: Domain.Model.Projects.Project at NHibernate.Impl.SessionFactoryImpl.GetEntityPersister(String entityName) at NHibernate.Impl.SessionImpl.GetEntityPersister(String entityName, Object obj) at NHibernate.Event.Default.AbstractSaveEventListener.SaveWithGeneratedId(Object entity, String entityName, Object anything, IEventSource source, Boolean requiresImmediateIdAccess) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.SaveWithGeneratedOrRequestedId(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveEventListener.SaveWithGeneratedOrRequestedId(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.EntityIsTransient(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveEventListener.PerformSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.OnSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.FireSave(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.Save(Object obj) NHibernate\Repository\NHibRepository.cs(40,0): at Core.Data.NHibernate.Repository.NHibRepository`1.Add(T item) Repositories\ProjectRepository.cs(30,0): at Data.Repositories.ProjectRepository.SaveAll(IEnumerable`1 projects) LegacyConversion\LegacyBatchUpdater.cs(20,0): at Data.LegacyConversion.LegacyBatchUpdater.ConvertOpenLegacyProjects(ILegacyProjectDao legacyProjectDao, IProjectRepository greenProjectRepository) Data\Brownfield\ProjectBatchUpdate_SQLiteTests.cs(31,0): at .Tests.Data.Brownfield.ProjectBatchUpdate_SQLiteTests.Test()

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  • equality on the sender of an event

    - by Berryl
    I have an interface for a UI widget, two of which are attributes of a presenter. public IMatrixWidget NonProjectActivityMatrix { set { // validate the incoming value and set the field _nonProjectActivityMatrix = value; .... // configure & load non-project activities } public IMatrixWidget ProjectActivityMatrix { set { // validate the incoming value and set the field _projectActivityMatrix = value; .... // configure & load project activities } The widget has an event that both presenter objects subscribe to, and so there is an event handler in the presenter like so: public void OnActivityEntry(object sender, EntryChangedEventArgs e) { // calculate newTotal here .... if (ReferenceEquals(sender, _nonProjectActivityMatrix)) { _nonProjectActivityMatrix.UpdateTotalHours(feedback.ActivityTotal); } else if (ReferenceEquals(sender, _projectActivityMatrix)) { _projectActivityMatrix.UpdateTotalHours(feedback.ActivityTotal); } else { // ERROR - we should never be here } } The problem is that the ReferenceEquals on the sender fails, even though it is the implemented widget that is the sender - the same implemented widget that was set to the presenter attribute! Can anyone spot what the problem / fix is? Cheers, Berryl I didn't know you could edit nicely. Cool. Here is the event raising code: void OnGridViewNumericUpDownEditingControl_ValueChanged(object sender, EventArgs e) { // omitted to save sapce if (EntryChanged == null) return; var args = new EntryChangedEventArgs(activityID, dayID, Convert.ToDouble(amount)); EntryChanged(this, args); } Here is the debugger dump of the presenter attribute, sans namespace info: ?_nonProjectActivityMatrix {WinPresentation.Widgets.MatrixWidgetDgv} [WinPresentation.Widgets.MatrixWidgetDgv]: {WinPresentation.Widgets.MatrixWidgetDgv} Here is the debugger dump of the sender: ?sender {WinPresentation.Widgets.MatrixWidgetDgv} base {Core.GUI.Widgets.Lookup.MatrixWidgetBase<Core.GUI.Widgets.Lookup.DynamicDisplayDto>}: {WinPresentation.Widgets.MatrixWidgetDgv} _configuration: {Domain.Presentation.Timesheet.Matrix.WeeklyMatrixConfiguration} _wrappedWidget: {Win.Widgets.DataGridViewDynamicLookupWidget} AllowUserToAddRows: true ColumnCount: 11 Count: 4 EntryChanged: {Method = {Void OnActivityEntry(System.Object, Smack.ConstructionAdmin.Domain.Presentation.Timesheet.Matrix.EntryChangedEventArgs)}} SelectedCell: {DataGridViewNumericUpDownCell { ColumnIndex=3, RowIndex=3 }} SelectedCellValue: "0.00" SelectedColumn: {DataGridViewNumericUpDownColumn { Name=MONDAY, Index=3 }} SelectedItem: {'AdministrativeActivity: 130-04', , AdministrativeTime, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00} Berryl

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  • PDF reviewer in C# (ASP.NET/Silverlight?)

    - by Anders Holmström
    Hi. I'm essentially planning to mimic the comment functions on PDF files, but online. That is; a user should be able to log in and upload a PDF file, and then numerous different users should be able to add comments etc to this same file (and view the file, with comments, online). External libraries are ok. Free obviously preferred, but commercial ones are fine if they provide a lot of the needed functionality. Note that this is meant to be used in a commercial environment. Comments don't necessarily need to be able to be exported from the site. I.e. if the comments are just put as a layer on top of a PDF file (and not in the actual file) that's ok. But obviously the more export functionality the better. I have looked at a few libraries (using the related questions and google) and while I find some that seem to do sort of what I want I'm not sure they are the bee's knees plus I would like to do as much myself as possible. The three basic approaches I've thought of is: Use some sort of native PDF viewing and then just smack down a layer on top of it where you can move around comments etc. Convert PDFs to HTML and work from there. Problem here it would either require proper PDFs (e.g. non-scanned) or really good OCR which seems a bit tedious. Convert PDFs to images and work from there. I'm afraid this will create massive images however. We're talking PDFs that can be hundreds of pages. One option would of course to just display one PDF page (image) at a time. And last - should I look at Silverlight for this or go with ASP.NET? Ideas and input concerning this project are much appreciated.

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  • How do I avoid the loader lock?

    - by Mark0978
    We have a managed app, that uses an assembly. That assembly uses some unmanaged C++ code. The Managed C++ code is in a dll, that depends on several other dlls. All of those Dlls are loaded by this code. (We load all the dll's that ImageCore.dll depends on first, so we can tell which ones are missing, otherwise it would just show up as ImageCore.dll failed to load, and the log file would give no clues as to why). class Interop { private const int DONT_RESOLVE_DLL_REFERENCES = 1; private static log4net.ILog log = log4net.LogManager.GetLogger("Imagecore.NET"); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr LoadLibraryEx(string fileName, IntPtr dummy, int flags); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr FreeLibrary(IntPtr hModule); static private String[] libs = { "log4cplus.dll", "yaz.dll", "zlib1.dll", "libxml2.dll" }; public static void PreloadAssemblies() { for (int i=0; i < libs.Length; ++i) { String libname = libs[i]; IntPtr hModule = LoadLibraryEx(libname, IntPtr.Zero, DONT_RESOLVE_DLL_REFERENCES); if(hModule == IntPtr.Zero) { log.Error("Unable to pre-load '" + libname + "'"); throw new DllNotFoundException("Unable to pre-load '" + libname + "'"); } else { FreeLibrary(hModule); } } IntPtr h = LoadLibraryEx("ImageCore.dll", IntPtr.Zero, 0); if (h == IntPtr.Zero) { throw new DllNotFoundException("Unable to pre-load ImageCore.dll"); } } } And this code is called by public class ImageDoc : IDisposable { static ImageDoc() { ImageHawk.ImageCore.Utility.Interop.PreloadAssemblies(); } ... } Which is static constructor. As near as I can understand it, as soon as we attempt to use an ImageDoc object, the dll that contains that assembly is loaded and as part of that load, the static constructor is called which in turn causes several other DLLs to be loaded as well. What I'm trying to figure out, is how do we defer loading of those DLLs so that we don't run smack dab into this loader lock that is being kicked out because of the static constructor. I've pieced this much together by looking at: http://social.msdn.microsoft.com/Forums/en-US/vsto/thread/dd192d7e-ce92-49ce-beef-3816c88e5a86 http://msdn.microsoft.com/en-us/library/aa290048%28VS.71%29.aspx http://forums.devx.com/showthread.php?t=53529 http://www.yoda.arachsys.com/csharp/beforefieldinit.html But I just can't seem to find a way to get these external DLLs to load without it happening at the point the class is loading. I think I need to get these LoadLibrary calls out of the static constructor, but don't know how to get them called before they are needed (except for how it is done here). I would prefer to not have to put this kind of knowledge of the dlls into every app that uses this assembly. (And I'm not sure that would even fix the problem.... The strange thing is that the exception only appears to be happening while running within the debugger, not while running outside the debugger.

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  • DependencyProperty binding not happening on initial load

    - by Ari Roth
    I'm trying to do something simple -- make a DependencyProperty and then bind to it. However, the getter doesn't appear to fire when I start up the app. (I'm guessing the solution will make me smack my head and go "Doh!", but still. :) ) Any ideas? Code-behind code: public static readonly DependencyProperty PriorityProperty = DependencyProperty.Register("Priority", typeof (Priority), typeof (PriorityControl), null); public Priority Priority { get { return (Priority)GetValue(PriorityProperty); } set { SetValue(PriorityProperty, value); } } Control XAML: <ListBox Background="Transparent" BorderThickness="0" ItemsSource="{Binding Path=Priorities}" Name="PriorityList" SelectedItem="{Binding Path=Priority, Mode=TwoWay}"> <ListBox.ItemTemplate> <DataTemplate> <Grid Height="16" Width="16"> <Border BorderBrush="Black" BorderThickness="2" CornerRadius="3" Visibility="{Binding RelativeSource= {RelativeSource Mode=FindAncestor, AncestorType=ListBoxItem}, Path=IsSelected, Converter={StaticResource boolToVisibilityConverter}}" /> <Border CornerRadius="3" Height="12" Width="12"> <Border.Background> <SolidColorBrush Color="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ListBoxItem}, Path=Content, Converter={StaticResource priorityToColorConverter}}" /> </Border.Background> </Border> </Grid> </DataTemplate> </ListBox.ItemTemplate> <ListBox.ItemsPanel> <ItemsPanelTemplate> <StackPanel Orientation="Horizontal"/> </ItemsPanelTemplate> </ListBox.ItemsPanel> </ListBox> Binding statement: <UI:PriorityControl Grid.Column="8" Priority="{Binding Path=Priority}" VerticalAlignment="Center"/> Some other notes: Binding is in a UserControl UserControl contains the PriorityControl PriorityControl contains the DependencyProperty I've checked that the data the UserControl is getting the appropriate data -- every other binding works. If I change the selection on the PriorityControl via the mouse, everything fires as appropriate. It's just that initial setting of the value that isn't working. Priority is an enum.

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  • Can Microsoft Build Appliances?

    - by andrewbrust
    Billy Hollis, my Visual Studio Live! colleague and fellow Microsoft Regional Director said recently, and I am paraphrasing, that the computing world, especially on the consumer side, has shifted from one of building hardware and software that makes things possible to do, to building products and technologies that make things easy to do.  Billy crystalized things perfectly, as he often does. In this new world of “easy to do,” Apple has done very well and Microsoft has struggled.  In the old world, customers wanted a Swiss Army Knife, with the most gimmicks and gadgets possible.  In the new world, people want elegantly cutlery.  They may want cake cutters and utility knives too, but they don’t want one device that works for all three tasks.  People don’t want tools, they want utensils.  People don’t want machines.  They want appliances. Microsoft Appliances: They Do Exist Microsoft has built a few appliance-like devices.  I would say XBox 360 is an appliance,  It’s versatile, mind you, but it’s the kind of thing you plug in, turn on and use, as opposed to set-up, tune, and open up to upgrade the internals.  Windows Phone 7 is an appliance too.  It’s a true smartphone, unlike Windows Mobile which was a handheld computer with a radio stack.  Zune is an appliance too, and a nice one.  It hasn’t attained much traction in the market, but that’s probably because the seminal consumer computing appliance -- the iPod – got there so much more quickly. In the embedded world, Mediaroom, Microsoft’s set-top product for the cable industry (used by AT&T U-Verse and others) is an appliance.  So is Microsoft’s Sync technology, used in Ford automobiles.  Even on the enterprise side, Microsoft has an appliance: SQL Server Parallel Data Warehouse Edition (PDW) combines Microsoft software with select OEMs’ server, networking and storage hardware.  You buy the appliance units from the OEMs, plug them in, connect them and go. I would even say that Bing is an appliance.  Not in the hardware sense, mind you.  But from the software perspective, it’s a single-purpose product that you visit or run, use and then move on.  You don’t have to install it (except the iOS and Android native apps where it’s pretty straightforward), you don’t have to customize it, you don’t have to program it.  Basically, you just use it. Microsoft Appliances that Should Exist But Microsoft builds a bunch of things that are not appliances.  Media Center is not an appliance, and it most certainly should be.  Instead, it’s an app that runs on Windows 7.  It runs full-screen and you can use this configuration to conceal the fact that Windows is under it, but eventually something will cause you to abandon that masquerade (like Patch Tuesday). The next version of Windows Home Server won’t, in my opinion, be an appliance either.  Now that the Drive Extender technology is gone, and users can’t just add and remove drives into and from a single storage pool, the product is much more like a IT server and less like an appliance-premised one.  Much has been written about this decision by Microsoft.  I’ll just sum it up in one word: pity. Microsoft doesn’t have anything remotely appliance-like in the tablet category, either.  Until it does, it likely won’t have much market share in that space either.  And of course, the bulk of Microsoft’s product catalog on the business side is geared to enterprise machines and not personal appliances. Appliance DNA: They Gotta Have It. The consumerization of IT is real, because businesspeople are consumers too.  They appreciate the fit and finish of appliances at home, and they increasingly feel entitled to have it at work too.  Secure and reliable push email in a smartphone is necessary, but it isn’t enough.  People want great apps and a pleasurable user experience too.  The full Microsoft Office product is needed at work, but a PC with a keyboard and mouse, or maybe a touch screen that uses a stylus (or requires really small fingers), to run Office isn’t enough either.  People want a flawless touch experience available for the times they want to read and take quick notes.  Until Microsoft realizes this fully and internalizes it, it will suffer defeats in the consumer market and even setbacks in the business market.  Think about how slow the Office upgrade cycle is…now imagine if the next version of Office had a first-class alternate touch UI and consider the possible acceleration in adoption rates. Can Microsoft make the appliance switch?  Can the appliance mentality become pervasive at the company?  Can Microsoft hasten its release cycles dramatically and shed the “some assembly required” paradigm upon which many of its products are based?  Let’s face it, the chances that Microsoft won’t make this transition are significant. But there are also encouraging signs, and they should not be ignored.  The appliances we have already discussed, especially Xbox, Zune and Windows Phone 7, are the most obvious in this regard.  The fact that SQL Server has an appliance SKU now is a more subtle but perhaps also more significant outcome, because that product sits so smack in the middle of Microsoft’s enterprise stack.  Bing is encouraging too, especially given its integrated travel, maps and augmented reality capabilities.  As Bing gains market share, Microsoft has tangible proof that it can transform and win, even when everyone outside the company, and many within it, would bet otherwise. That Great Big Appliance in the Sky Perhaps the most promising (and evolving) proof points toward the appliance mentality, though, are Microsoft’s cloud offerings -- Azure and BPOS/Office 365.  While the cloud does not represent a physical appliance (quite the opposite in fact) its ability to make acquisition, deployment and use of technology simple for the user is absolutely an embodiment of the appliance mentality and spirit.  Azure is primarily a platform as a service offering; it doesn’t just provide infrastructure.  SQL Azure does likewise for databases.  And Office 365 does likewise for SharePoint, Exchange and Lync. You don’t administer, tune and manage servers; instead, you create databases or site collections or mailboxes and start using them. Upgrades come automatically, and it seems like releases will come more frequently.  Fault tolerance and content distribution is just there.  No muss.  No fuss.  You use these services; you don’t have to set them up and think about them.  That’s how appliances work.  To me, these signs point out that Microsoft has the full capability of transforming itself.  But there’s a lot of work ahead.  Microsoft may say they’re “all in” on the cloud, but the majority of the company is still oriented around its old products and models.  There needs to be a wholesale cultural transformation in Redmond.  It can happen, but product management, program management, the field and executive ranks must unify in the effort. So must partners, and even customers.  New leaders must rise up and Microsoft must be able to see itself as a winner.  If Microsoft does this, it could lock-in decades of new success, and be a standard business school case study for doing so.  If not, the company will have missed an opportunity, and may see its undoing.

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  • DBCC CHECKDB on VVLDB and latches (Or: My Pain is Your Gain)

    - by Argenis
      Does your CHECKDB hurt, Argenis? There is a classic blog series by Paul Randal [blog|twitter] called “CHECKDB From Every Angle” which is pretty much mandatory reading for anybody who’s even remotely considering going for the MCM certification, or its replacement (the Microsoft Certified Solutions Master: Data Platform – makes my fingers hurt just from typing it). Of particular interest is the post “Consistency Options for a VLDB” – on it, Paul provides solid, timeless advice (I use the word “timeless” because it was written in 2007, and it all applies today!) on how to perform checks on very large databases. Well, here I was trying to figure out how to make CHECKDB run faster on a restored copy of one of our databases, which happens to exceed 7TB in size. The whole thing was taking several days on multiple systems, regardless of the storage used – SAS, SATA or even SSD…and I actually didn’t pay much attention to how long it was taking, or even bothered to look at the reasons why - as long as it was finishing okay and found no consistency errors. Yes – I know. That was a huge mistake, as corruption found in a database several days after taking place could only allow for further spread of the corruption – and potentially large data loss. In the last two weeks I increased my attention towards this problem, as we noticed that CHECKDB was taking EVEN LONGER on brand new all-flash storage in the SAN! I couldn’t really explain it, and were almost ready to blame the storage vendor. The vendor told us that they could initially see the server driving decent I/O – around 450Mb/sec, and then it would settle at a very slow rate of 10Mb/sec or so. “Hum”, I thought – “CHECKDB is just not pushing the I/O subsystem hard enough”. Perfmon confirmed the vendor’s observations. Dreaded @BlobEater What was CHECKDB doing all the time while doing so little I/O? Eating Blobs. It turns out that CHECKDB was taking an extremely long time on one of our frankentables, which happens to be have 35 billion rows (yup, with a b) and sucks up several terabytes of space in the database. We do have a project ongoing to purge/split/partition this table, so it’s just a matter of time before we deal with it. But the reality today is that CHECKDB is coming to a screeching halt in performance when dealing with this particular table. Checking sys.dm_os_waiting_tasks and sys.dm_os_latch_stats showed that LATCH_EX (DBCC_OBJECT_METADATA) was by far the top wait type. I remembered hearing recently about that wait from another post that Paul Randal made, but that was related to computed-column indexes, and in fact, Paul himself reminded me of his article via twitter. But alas, our pathologic table had no non-clustered indexes on computed columns. I knew that latches are used by the database engine to do internal synchronization – but how could I help speed this up? After all, this is stuff that doesn’t have a lot of knobs to tweak. (There’s a fantastic level 500 talk by Bob Ward from Microsoft CSS [blog|twitter] called “Inside SQL Server Latches” given at PASS 2010 – and you can check it out here. DISCLAIMER: I assume no responsibility for any brain melting that might ensue from watching Bob’s talk!) Failed Hypotheses Earlier on this week I flew down to Palo Alto, CA, to visit our Headquarters – and after having a great time with my Monkey peers, I was relaxing on the plane back to Seattle watching a great talk by SQL Server MVP and fellow MCM Maciej Pilecki [twitter] called “Masterclass: A Day in the Life of a Database Transaction” where he discusses many different topics related to transaction management inside SQL Server. Very good stuff, and when I got home it was a little late – that slow DBCC CHECKDB that I had been dealing with was way in the back of my head. As I was looking at the problem at hand earlier on this week, I thought “How about I set the database to read-only?” I remembered one of the things Maciej had (jokingly) said in his talk: “if you don’t want locking and blocking, set the database to read-only” (or something to that effect, pardon my loose memory). I immediately killed the CHECKDB which had been running painfully for days, and set the database to read-only mode. Then I ran DBCC CHECKDB against it. It started going really fast (even a bit faster than before), and then throttled down again to around 10Mb/sec. All sorts of expletives went through my head at the time. Sure enough, the same latching scenario was present. Oh well. I even spent some time trying to figure out if NUMA was hurting performance. Folks on Twitter made suggestions in this regard (thanks, Lonny! [twitter]) …Eureka? This past Friday I was still scratching my head about the whole thing; I was ready to start profiling with XPERF to see if I could figure out which part of the engine was to blame and then get Microsoft to look at the evidence. After getting a bunch of good news I’ll blog about separately, I sat down for a figurative smack down with CHECKDB before the weekend. And then the light bulb went on. A sparse column. I thought that I couldn’t possibly be experiencing the same scenario that Paul blogged about back in March showing extreme latching with non-clustered indexes on computed columns. Did I even have a non-clustered index on my sparse column? As it turns out, I did. I had one filtered non-clustered index – with the sparse column as the index key (and only column). To prove that this was the problem, I went and setup a test. Yup, that'll do it The repro is very simple for this issue: I tested it on the latest public builds of SQL Server 2008 R2 SP2 (CU6) and SQL Server 2012 SP1 (CU4). First, create a test database and a test table, which only needs to contain a sparse column: CREATE DATABASE SparseColTest; GO USE SparseColTest; GO CREATE TABLE testTable (testCol smalldatetime SPARSE NULL); GO INSERT INTO testTable (testCol) VALUES (NULL); GO 1000000 That’s 1 million rows, and even though you’re inserting NULLs, that’s going to take a while. In my laptop, it took 3 minutes and 31 seconds. Next, we run DBCC CHECKDB against the database: DBCC CHECKDB('SparseColTest') WITH NO_INFOMSGS, ALL_ERRORMSGS; This runs extremely fast, as least on my test rig – 198 milliseconds. Now let’s create a filtered non-clustered index on the sparse column: CREATE NONCLUSTERED INDEX [badBadIndex] ON testTable (testCol) WHERE testCol IS NOT NULL; With the index in place now, let’s run DBCC CHECKDB one more time: DBCC CHECKDB('SparseColTest') WITH NO_INFOMSGS, ALL_ERRORMSGS; In my test system this statement completed in 11433 milliseconds. 11.43 full seconds. Quite the jump from 198 milliseconds. I went ahead and dropped the filtered non-clustered indexes on the restored copy of our production database, and ran CHECKDB against that. We went down from 7+ days to 19 hours and 20 minutes. Cue the “Argenis is not impressed” meme, please, Mr. LaRock. My pain is your gain, folks. Go check to see if you have any of such indexes – they’re likely causing your consistency checks to run very, very slow. Happy CHECKDBing, -Argenis ps: I plan to file a Connect item for this issue – I consider it a pretty serious bug in the engine. After all, filtered indexes were invented BECAUSE of the sparse column feature – and it makes a lot of sense to use them together. Watch this space and my twitter timeline for a link.

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  • Set-Cookie Headers getting stripped in ASP.NET HttpHandlers

    - by Rick Strahl
    Yikes, I ran into a real bummer of an edge case yesterday in one of my older low level handler implementations (for West Wind Web Connection in this case). Basically this handler is a connector for a backend Web framework that creates self contained HTTP output. An ASP.NET Handler captures the full output, and then shoves the result down the ASP.NET Response object pipeline writing out the content into the Response.OutputStream and seperately sending the HttpHeaders in the Response.Headers collection. The headers turned out to be the problem and specifically Http Cookies, which for some reason ended up getting stripped out in some scenarios. My handler works like this: Basically the HTTP response from the backend app would return a full set of HTTP headers plus the content. The ASP.NET handler would read the headers one at a time and then dump them out via Response.AppendHeader(). But I found that in some situations Set-Cookie headers sent along were simply stripped inside of the Http Handler. After a bunch of back and forth with some folks from Microsoft (thanks Damien and Levi!) I managed to pin this down to a very narrow edge scenario. It's easiest to demonstrate the problem with a simple example HttpHandler implementation. The following simulates the very much simplified output generation process that fails in my handler. Specifically I have a couple of headers including a Set-Cookie header and some output that gets written into the Response object.using System.Web; namespace wwThreads { public class Handler : IHttpHandler { /* NOTE: * * Run as a web.config set handler (see entry below) * * Best way is to look at the HTTP Headers in Fiddler * or Chrome/FireBug/IE tools and look for the * WWHTREADSID cookie in the outgoing Response headers * ( If the cookie is not there you see the problem! ) */ public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; HttpResponse response = context.Response; // If ClearHeaders is used Set-Cookie header gets removed! // if commented header is sent... response.ClearHeaders(); response.ClearContent(); // Demonstrate that other headers make it response.AppendHeader("RequestId", "asdasdasd"); // This cookie gets removed when ClearHeaders above is called // When ClearHEaders is omitted above the cookie renders response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); // *** This always works, even when explicit // Set-Cookie above fails and ClearHeaders is called //response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); response.Write(@"Output was created.<hr/> Check output with Fiddler or HTTP Proxy to see whether cookie was sent."); } public bool IsReusable { get { return false; } } } } In order to see the problem behavior this code has to be inside of an HttpHandler, and specifically in a handler defined in web.config with: <add name=".ck_handler" path="handler.ck" verb="*" type="wwThreads.Handler" preCondition="integratedMode" /> Note: Oddly enough this problem manifests only when configured through web.config, not in an ASHX handler, nor if you paste that same code into an ASPX page or MVC controller. What's the problem exactly? The code above simulates the more complex code in my live handler that picks up the HTTP response from the backend application and then peels out the headers and sends them one at a time via Response.AppendHeader. One of the headers in my app can be one or more Set-Cookie. I found that the Set-Cookie headers were not making it into the Response headers output. Here's the Chrome Http Inspector trace: Notice, no Set-Cookie header in the Response headers! Now, running the very same request after removing the call to Response.ClearHeaders() command, the cookie header shows up just fine: As you might expect it took a while to track this down. At first I thought my backend was not sending the headers but after closer checks I found that indeed the headers were set in the backend HTTP response, and they were indeed getting set via Response.AppendHeader() in the handler code. Yet, no cookie in the output. In the simulated example the problem is this line:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); which in my live code is more dynamic ( ie. AppendHeader(token[0],token[1[]) )as it parses through the headers. Bizzaro Land: Response.ClearHeaders() causes Cookie to get stripped Now, here is where it really gets bizarre: The problem occurs only if: Response.ClearHeaders() was called before headers are added It only occurs in Http Handlers declared in web.config Clearly this is an edge of an edge case but of course - knowing my relationship with Mr. Murphy - I ended up running smack into this problem. So in the code above if you remove the call to ClearHeaders(), the cookie gets set!  Add it back in and the cookie is not there. If I run the above code in an ASHX handler it works. If I paste the same code (with a Response.End()) into an ASPX page, or MVC controller it all works. Only in the HttpHandler configured through Web.config does it fail! Cue the Twilight Zone Music. Workarounds As is often the case the fix for this once you know the problem is not too difficult. The difficulty lies in tracking inconsistencies like this down. Luckily there are a few simple workarounds for the Cookie issue. Don't use AppendHeader for Cookies The easiest and obvious solution to this problem is simply not use Response.AppendHeader() to set Cookies. Duh! Under normal circumstances in application level code there's rarely a reason to write out a cookie like this:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); but rather create the cookie using the Response.Cookies collection:response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); Unfortunately, in my case where I dynamically read headers from the original output and then dynamically  write header key value pairs back  programmatically into the Response.Headers collection, I actually don't look at each header specifically so in my case the cookie is just another header. My first thought was to simply trap for the Set-Cookie header and then parse out the cookie and create a Cookie object instead. But given that cookies can have a lot of different options this is not exactly trivial, plus I don't really want to fuck around with cookie values which can be notoriously brittle. Don't use Response.ClearHeaders() The real mystery in all this is why calling Response.ClearHeaders() prevents a cookie value later written with Response.AppendHeader() to fail. I fired up Reflector and took a quick look at System.Web and HttpResponse.ClearHeaders. There's all sorts of resetting going on but nothing that seems to indicate that headers should be removed later on in the request. The code in ClearHeaders() does access the HttpWorkerRequest, which is the low level interface directly into IIS, and so I suspect it's actually IIS that's stripping the headers and not ASP.NET, but it's hard to know. Somebody from Microsoft and the IIS team would have to comment on that. In my application it's probably safe to simply skip ClearHeaders() in my handler. The ClearHeaders/ClearContent was mainly for safety but after reviewing my code there really should never be a reason that headers would be set prior to this method firing. However, if for whatever reason headers do need to be cleared, it's easy enough to manually clear the headers out:private void RemoveHeaders(HttpResponse response) { List<string> headers = new List<string>(); foreach (string header in response.Headers) { headers.Add(header); } foreach (string header in headers) { response.Headers.Remove(header); } response.Cookies.Clear(); } Now I can replace the call the Response.ClearHeaders() and I don't get the funky side-effects from Response.ClearHeaders(). Summary I realize this is a total edge case as this occurs only in HttpHandlers that are manually configured. It looks like you'll never run into this in any of the higher level ASP.NET frameworks or even in ASHX handlers - only web.config defined handlers - which is really, really odd. After all those frameworks use the same underlying ASP.NET architecture. Hopefully somebody from Microsoft has an idea what crazy dependency was triggered here to make this fail. IAC, there are workarounds to this should you run into it, although I bet when you do run into it, it'll likely take a bit of time to find the problem or even this post in a search because it's not easily to correlate the problem to the solution. It's quite possible that more than cookies are affected by this behavior. Searching for a solution I read a few other accounts where headers like Referer were mysteriously disappearing, and it's possible that something similar is happening in those cases. Again, extreme edge case, but I'm writing this up here as documentation for myself and possibly some others that might have run into this. © Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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