Search Results

Search found 7264 results on 291 pages for 'deferred loading'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 8/291 | < Previous Page | 4 5 6 7 8 9 10 11 12 13 14 15  | Next Page >

  • ODI 12c - Loading Files into Oracle, community post from ToadWorld

    - by David Allan
    There's a complete soup to nuts post from Deepak Vohra on the Oracle community pages of ToadWorld on loading a fixed length file into the Oracle database. This post is interesting from a few fronts; firstly this is the out of the box experience, no specialized KMs so just basic integration from getting the software installed to running a mapping. Also it demonstrates fixed length file integration including how to use the ODI UI to define the fields and pertinent properties.  Check the blog post out below.... http://www.toadworld.com/platforms/oracle/w/wiki/10935.loading-text-file-data-into-oracle-database-12c-with-oracle-data-integrator-12c.aspx Hopefully you also find this useful, many thanks to Deepak for sharing his experiences. You could take this example further and illustrate how to load into Oracle using the LKM File to Oracle via External table knowledge module which will perform much better and also leverage such things as using wildcards for loading many files into the 12c database.

    Read the article

  • Dynamically loading Assemblies to reduce Runtime Depencies

    - by Rick Strahl
    I've been working on a request to the West Wind Application Configuration library to add JSON support. The config library is a very easy to use code-first approach to configuration: You create a class that holds the configuration data that inherits from a base configuration class, and then assign a persistence provider at runtime that determines where and how the configuration data is store. Currently the library supports .NET Configuration stores (web.config/app.config), XML files, SQL records and string storage.About once a week somebody asks me about JSON support and I've deflected this question for the longest time because frankly I think that JSON as a configuration store doesn't really buy a heck of a lot over XML. Both formats require the user to perform some fixup of the plain configuration data - in XML into XML tags, with JSON using JSON delimiters for properties and property formatting rules. Sure JSON is a little less verbose and maybe a little easier to read if you have hierarchical data, but overall the differences are pretty minor in my opinion. And yet - the requests keep rolling in.Hard Link Issues in a Component LibraryAnother reason I've been hesitant is that I really didn't want to pull in a dependency on an external JSON library - in this case JSON.NET - into the core library. If you're not using JSON.NET elsewhere I don't want a user to have to require a hard dependency on JSON.NET unless they want to use the JSON feature. JSON.NET is also sensitive to versions and doesn't play nice with multiple versions when hard linked. For example, when you have a reference to V4.4 in your project but the host application has a reference to version 4.5 you can run into assembly load problems. NuGet's Update-Package can solve some of this *if* you can recompile, but that's not ideal for a component that's supposed to be just plug and play. This is no criticism of JSON.NET - this really applies to any dependency that might change.  So hard linking the DLL can be problematic for a number reasons, but the primary reason is to not force loading of JSON.NET unless you actually need it when you use the JSON configuration features of the library.Enter Dynamic LoadingSo rather than adding an assembly reference to the project, I decided that it would be better to dynamically load the DLL at runtime and then use dynamic typing to access various classes. This allows me to run without a hard assembly reference and allows more flexibility with version number differences now and in the future.But there are also a couple of downsides:No assembly reference means only dynamic access - no compiler type checking or IntellisenseRequirement for the host application to have reference to JSON.NET or else get runtime errorsThe former is minor, but the latter can be problematic. Runtime errors are always painful, but in this case I'm willing to live with this. If you want to use JSON configuration settings JSON.NET needs to be loaded in the project. If this is a Web project, it'll likely be there already.So there are a few things that are needed to make this work:Dynamically create an instance and optionally attempt to load an Assembly (if not loaded)Load types into dynamic variablesUse Reflection for a few tasks like statics/enumsThe dynamic keyword in C# makes the formerly most difficult Reflection part - method calls and property assignments - fairly painless. But as cool as dynamic is it doesn't handle all aspects of Reflection. Specifically it doesn't deal with object activation, truly dynamic (string based) member activation or accessing of non instance members, so there's still a little bit of work left to do with Reflection.Dynamic Object InstantiationThe first step in getting the process rolling is to instantiate the type you need to work with. This might be a two step process - loading the instance from a string value, since we don't have a hard type reference and potentially having to load the assembly. Although the host project might have a reference to JSON.NET, that instance might have not been loaded yet since it hasn't been accessed yet. In ASP.NET this won't be a problem, since ASP.NET preloads all referenced assemblies on AppDomain startup, but in other executable project, assemblies are just in time loaded only when they are accessed.Instantiating a type is a two step process: Finding the type reference and then activating it. Here's the generic code out of my ReflectionUtils library I use for this:/// <summary> /// Creates an instance of a type based on a string. Assumes that the type's /// </summary> /// <param name="typeName">Common name of the type</param> /// <param name="args">Any constructor parameters</param> /// <returns></returns> public static object CreateInstanceFromString(string typeName, params object[] args) { object instance = null; Type type = null; try { type = GetTypeFromName(typeName); if (type == null) return null; instance = Activator.CreateInstance(type, args); } catch { return null; } return instance; } /// <summary> /// Helper routine that looks up a type name and tries to retrieve the /// full type reference in the actively executing assemblies. /// </summary> /// <param name="typeName"></param> /// <returns></returns> public static Type GetTypeFromName(string typeName) { Type type = null; // Let default name binding find it type = Type.GetType(typeName, false); if (type != null) return type; // look through assembly list var assemblies = AppDomain.CurrentDomain.GetAssemblies(); // try to find manually foreach (Assembly asm in assemblies) { type = asm.GetType(typeName, false); if (type != null) break; } return type; } To use this for loading JSON.NET I have a small factory function that instantiates JSON.NET and sets a bunch of configuration settings on the generated object. The startup code also looks for failure and tries loading up the assembly when it fails since that's the main reason the load would fail. Finally it also caches the loaded instance for reuse (according to James the JSON.NET instance is thread safe and quite a bit faster when cached). Here's what the factory function looks like in JsonSerializationUtils:/// <summary> /// Dynamically creates an instance of JSON.NET /// </summary> /// <param name="throwExceptions">If true throws exceptions otherwise returns null</param> /// <returns>Dynamic JsonSerializer instance</returns> public static dynamic CreateJsonNet(bool throwExceptions = true) { if (JsonNet != null) return JsonNet; lock (SyncLock) { if (JsonNet != null) return JsonNet; // Try to create instance dynamic json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); if (json == null) { try { var ass = AppDomain.CurrentDomain.Load("Newtonsoft.Json"); json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); } catch (Exception ex) { if (throwExceptions) throw; return null; } } if (json == null) return null; json.ReferenceLoopHandling = (dynamic) ReflectionUtils.GetStaticProperty("Newtonsoft.Json.ReferenceLoopHandling", "Ignore"); // Enums as strings in JSON dynamic enumConverter = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.Converters.StringEnumConverter"); json.Converters.Add(enumConverter); JsonNet = json; } return JsonNet; }This code's purpose is to return a fully configured JsonSerializer instance. As you can see the code tries to create an instance and when it fails tries to load the assembly, and then re-tries loading.Once the instance is loaded some configuration occurs on it. Specifically I set the ReferenceLoopHandling option to not blow up immediately when circular references are encountered. There are a host of other small config setting that might be useful to set, but the default seem to be good enough in recent versions. Note that I'm setting ReferenceLoopHandling which requires an Enum value to be set. There's no real easy way (short of using the cardinal numeric value) to set a property or pass parameters from static values or enums. This means I still need to use Reflection to make this work. I'm using the same ReflectionUtils class I previously used to handle this for me. The function looks up the type and then uses Type.InvokeMember() to read the static property.Another feature I need is have Enum values serialized as strings rather than numeric values which is the default. To do this I can use the StringEnumConverter to convert enums to strings by adding it to the Converters collection.As you can see there's still a bit of Reflection to be done even in C# 4+ with dynamic, but with a few helpers this process is relatively painless.Doing the actual JSON ConversionFinally I need to actually do my JSON conversions. For the Utility class I need serialization that works for both strings and files so I created four methods that handle these tasks two each for serialization and deserialization for string and file.Here's what the File Serialization looks like:/// <summary> /// Serializes an object instance to a JSON file. /// </summary> /// <param name="value">the value to serialize</param> /// <param name="fileName">Full path to the file to write out with JSON.</param> /// <param name="throwExceptions">Determines whether exceptions are thrown or false is returned</param> /// <param name="formatJsonOutput">if true pretty-formats the JSON with line breaks</param> /// <returns>true or false</returns> public static bool SerializeToFile(object value, string fileName, bool throwExceptions = false, bool formatJsonOutput = false) { dynamic writer = null; FileStream fs = null; try { Type type = value.GetType(); var json = CreateJsonNet(throwExceptions); if (json == null) return false; fs = new FileStream(fileName, FileMode.Create); var sw = new StreamWriter(fs, Encoding.UTF8); writer = Activator.CreateInstance(JsonTextWriterType, sw); if (formatJsonOutput) writer.Formatting = (dynamic)Enum.Parse(FormattingType, "Indented"); writer.QuoteChar = '"'; json.Serialize(writer, value); } catch (Exception ex) { Debug.WriteLine("JsonSerializer Serialize error: " + ex.Message); if (throwExceptions) throw; return false; } finally { if (writer != null) writer.Close(); if (fs != null) fs.Close(); } return true; }You can see more of the dynamic invocation in this code. First I grab the dynamic JsonSerializer instance using the CreateJsonNet() method shown earlier which returns a dynamic. I then create a JsonTextWriter and configure a couple of enum settings on it, and then call Serialize() on the serializer instance with the JsonTextWriter that writes the output to disk. Although this code is dynamic it's still fairly short and readable.For full circle operation here's the DeserializeFromFile() version:/// <summary> /// Deserializes an object from file and returns a reference. /// </summary> /// <param name="fileName">name of the file to serialize to</param> /// <param name="objectType">The Type of the object. Use typeof(yourobject class)</param> /// <param name="binarySerialization">determines whether we use Xml or Binary serialization</param> /// <param name="throwExceptions">determines whether failure will throw rather than return null on failure</param> /// <returns>Instance of the deserialized object or null. Must be cast to your object type</returns> public static object DeserializeFromFile(string fileName, Type objectType, bool throwExceptions = false) { dynamic json = CreateJsonNet(throwExceptions); if (json == null) return null; object result = null; dynamic reader = null; FileStream fs = null; try { fs = new FileStream(fileName, FileMode.Open, FileAccess.Read); var sr = new StreamReader(fs, Encoding.UTF8); reader = Activator.CreateInstance(JsonTextReaderType, sr); result = json.Deserialize(reader, objectType); reader.Close(); } catch (Exception ex) { Debug.WriteLine("JsonNetSerialization Deserialization Error: " + ex.Message); if (throwExceptions) throw; return null; } finally { if (reader != null) reader.Close(); if (fs != null) fs.Close(); } return result; }This code is a little more compact since there are no prettifying options to set. Here JsonTextReader is created dynamically and it receives the output from the Deserialize() operation on the serializer.You can take a look at the full JsonSerializationUtils.cs file on GitHub to see the rest of the operations, but the string operations are very similar - the code is fairly repetitive.These generic serialization utilities isolate the dynamic serialization logic that has to deal with the dynamic nature of JSON.NET, and any code that uses these functions is none the wiser that JSON.NET is dynamically loaded.Using the JsonSerializationUtils WrapperThe final consumer of the SerializationUtils wrapper is an actual ConfigurationProvider, that is responsible for handling reading and writing JSON values to and from files. The provider is simple a small wrapper around the SerializationUtils component and there's very little code to make this work now:The whole provider looks like this:/// <summary> /// Reads and Writes configuration settings in .NET config files and /// sections. Allows reading and writing to default or external files /// and specification of the configuration section that settings are /// applied to. /// </summary> public class JsonFileConfigurationProvider<TAppConfiguration> : ConfigurationProviderBase<TAppConfiguration> where TAppConfiguration: AppConfiguration, new() { /// <summary> /// Optional - the Configuration file where configuration settings are /// stored in. If not specified uses the default Configuration Manager /// and its default store. /// </summary> public string JsonConfigurationFile { get { return _JsonConfigurationFile; } set { _JsonConfigurationFile = value; } } private string _JsonConfigurationFile = string.Empty; public override bool Read(AppConfiguration config) { var newConfig = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfiguration)) as TAppConfiguration; if (newConfig == null) { if(Write(config)) return true; return false; } DecryptFields(newConfig); DataUtils.CopyObjectData(newConfig, config, "Provider,ErrorMessage"); return true; } /// <summary> /// Return /// </summary> /// <typeparam name="TAppConfig"></typeparam> /// <returns></returns> public override TAppConfig Read<TAppConfig>() { var result = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfig)) as TAppConfig; if (result != null) DecryptFields(result); return result; } /// <summary> /// Write configuration to XmlConfigurationFile location /// </summary> /// <param name="config"></param> /// <returns></returns> public override bool Write(AppConfiguration config) { EncryptFields(config); bool result = JsonSerializationUtils.SerializeToFile(config, JsonConfigurationFile,false,true); // Have to decrypt again to make sure the properties are readable afterwards DecryptFields(config); return result; } }This incidentally demonstrates how easy it is to create a new provider for the West Wind Application Configuration component. Simply implementing 3 methods will do in most cases.Note this code doesn't have any dynamic dependencies - all that's abstracted away in the JsonSerializationUtils(). From here on, serializing JSON is just a matter of calling the static methods on the SerializationUtils class.Already, there are several other places in some other tools where I use JSON serialization this is coming in very handy. With a couple of lines of code I was able to add JSON.NET support to an older AJAX library that I use replacing quite a bit of code that was previously in use. And for any other manual JSON operations (in a couple of apps I use JSON Serialization for 'blob' like document storage) this is also going to be handy.Performance?Some of you might be thinking that using dynamic and Reflection can't be good for performance. And you'd be right… In performing some informal testing it looks like the performance of the native code is nearly twice as fast as the dynamic code. Most of the slowness is attributable to type lookups. To test I created a native class that uses an actual reference to JSON.NET and performance was consistently around 85-90% faster with the referenced code. That being said though - I serialized 10,000 objects in 80ms vs. 45ms so this isn't hardly slouchy. For the configuration component speed is not that important because both read and write operations typically happen once on first access and then every once in a while. But for other operations - say a serializer trying to handle AJAX requests on a Web Server one would be well served to create a hard dependency.Dynamic Loading - Worth it?On occasion dynamic loading makes sense. But there's a price to be paid in added code complexity and a performance hit. But for some operations that are not pivotal to a component or application and only used under certain circumstances dynamic loading can be beneficial to avoid having to ship extra files and loading down distributions. These days when you create new projects in Visual Studio with 30 assemblies before you even add your own code, trying to keep file counts under control seems a good idea. It's not the kind of thing you do on a regular basis, but when needed it can be a useful tool. Hopefully some of you find this information useful…© Rick Strahl, West Wind Technologies, 2005-2013Posted in .NET  C#   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); })();

    Read the article

  • Install wont boot up, stuck on loading text dots / restarts

    - by Franz Mayo Horkovic
    Friend gave me her laptop, we agreed on Ubuntu, but I have troubles even booting up live version (see the notebook). I tried 12.04 64bit on USB stick, it does nothing, when I choose booting live version, it just restarts PC. Then I tried 32bit version, it starts loading, but its stuck on loading components, printing on black screen just dots ........... I Googled it, found similar problem - somebody suggested to use older version and then upgrade it. I went through 11.04, 10.04 - 64 and 32 same result. Restart or infinite loading. I did memtest, it showed 4 errors, Windows Vista is running "fine", no "bluescreens" etc. Any ideas what am I doing wrong?

    Read the article

  • Android loading screens blocking, good practice?

    - by Oren
    I've noticed many (if not all) android games don't support the "back" button functionality during their loading screens. Which leads to some frustrating moments when a user accidentally starts up the game and has to wait for the long loading stage to end in order to close it. So my questions are: 1) Why is that ? Is there a good reason to avoid something like asynchronous loading (or some other solution to this problem) in android games ? 2) If there is no good reason not to support this functionality, what would be the best way to accomplish it ?

    Read the article

  • Dynamic XAP loading in Task-It - Part 1

    Download Source Code NOTE 1: The source code provided is running against the RC versions of Silverlight 4 and VisualStudio 2010, so you will need to update to those bits to run it. NOTE 2: After downloading the source, be sure to set the .Web project as the StartUp Project, and Default.aspx as the Start Page In my MEF into post, MEF to the rescue in Task-It, I outlined a couple of issues I was facing and explained why I chose MEF (the Managed Extensibility Framework) to solve these issues. Other posts to check out There are a few other resources out there around dynamic XAP loading that you may want to review (by the way, Glenn Block is the main dude when it comes to MEF): Glenn Blocks 3-part series on a dynamically loaded dashboard Glenn and John Papas Silverlight TV video on dynamic xap loading These provide some great info, but didnt exactly cover the scenario I wanted to achieve in Task-Itand that is dynamically loading each of the apps pages the first time the user enters a page. The code In the code I provided for download above, I created a simple solution that shows the technique I used for dynamic XAP loading in Task-It, but without all of the other code that surrounds it. Taking all that other stuff away should make it easier to grasp. Having said that, there is still a fair amount of code involved. I am always looking for ways to make things simpler, and to achieve the desired result with as little code as possible, so if I find a better/simpler way I will blog about it, but for now this technique works for me. When I created this solution I started by creating a new Silverlight Navigation Application called DynamicXAP Loading. I then added the following line to my UriMappings in MainPage.xaml: <uriMapper:UriMapping Uri="/{assemblyName};component/{path}" MappedUri="/{assemblyName};component/{path}"/> In the section of MainPage.xaml that produces the page links in the upper right, I kept the Home link, but added a couple of new ones (page1 and page 2). These are the pages that will be dynamically (lazy) loaded: <StackPanel x:Name="LinksStackPanel" Style="{StaticResource LinksStackPanelStyle}">      <HyperlinkButton Style="{StaticResource LinkStyle}" NavigateUri="/Home" TargetName="ContentFrame" Content="home"/>      <Rectangle Style="{StaticResource DividerStyle}"/>      <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 1" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage1}"/>      <Rectangle Style="{StaticResource DividerStyle}"/>      <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 2" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage2}"/>  </StackPanel> In App.xaml.cs I added a bit of MEF code. In Application_Startup I call a method called InitializeContainer, which creates a PackageCatalog (a MEF thing), then I create a CompositionContainer and pass it to the CompositionHost.Initialize method. This is boiler-plate MEF stuff that allows you to do 'composition' and import 'packages'. You're welcome to do a bit more MEF research on what is happening here if you'd like, but for the purpose of this example you can just trust that it works. :-) private void Application_Startup(object sender, StartupEventArgs e) {     InitializeContainer();     this.RootVisual = new MainPage(); }   private static void InitializeContainer() {     var catalog = new PackageCatalog();     catalog.AddPackage(Package.Current);     var container = new CompositionContainer(catalog);     container.ComposeExportedValue(catalog);     CompositionHost.Initialize(container); } Infrastructure In the sample code you'll notice that there is a project in the solution called DynamicXAPLoading.Infrastructure. This is simply a Silverlight Class Library project that I created just to move stuff I considered application 'infrastructure' code into a separate place, rather than cluttering the main Silverlight project (DynamicXapLoading). I did this same thing in Task-It, as the amount of this type of code was starting to clutter up the Silverlight project, and it just seemed to make sense to move things like Enums, Constants and the like off to a separate place. In the DynamicXapLoading.Infrastructure project you'll see 3 classes: Enums - There is only one enum in here called ModuleEnum. We'll use these later. PageMetadata - We will use this class later to add metadata to a new dynamically loaded project. ViewModelBase - This is simply a base class for view models that we will use in this, as well as future samples. As mentioned in my MVVM post, I will be using the MVVM pattern throughout my code for reasons detailed in the post. By the way, the ViewModelExtension class in there allows me to do strongly-typed property changed notification, so rather than OnPropertyChanged("MyProperty"), I can do this.OnPropertyChanged(p => p.MyProperty). It's just a less error-prown approach, because if you don't spell "MyProperty" correctly using the first method, nothing will break, it just won't work. Adding a new page We currently have a couple of pages that are being dynamically (lazy) loaded, but now let's add a third page. 1. First, create a new Silverlight Application project: In this example I call it Page3. In the future you may prefer to use a different name, like DynamicXAPLoading.Page3, or even DynamicXAPLoading.Modules.Page3. It can be whatever you want. In my Task-It application I used the latter approach (with 'Modules' in the name). I do think of these application as 'modules', but Prism uses the same term, so some folks may not like that. Use whichever naming convention you feel is appropriate, but for now Page3 will do. When you change the name to Page3 and click OK, you will be presented with the Add New Project dialog: It is important that you leave the 'Host the Silverlight application in a new or existing Web site in the solution' checked, and the .Web project will be selected in the dropdown below. This will create the .xap file for this project under ClientBin in the .Web project, which is where we want it. 2. Uncheck the 'Add a test page that references the application' checkbox, and leave everything else as is. 3. Once the project is created, you can delete App.xaml and MainPage.xaml. 4. You will need to add references your new project to the following: DynamicXAPLoading.Infrastructure.dll (this is a Project reference) DynamicNavigation.dll (this is in the Libs directory under the DynamicXAPLoading project) System.ComponentModel.Composition.dll System.ComponentModel.Composition.Initialization.dll System.Windows.Controls.Navigation.dll If you have installed the latest RC bits you will find the last 3 dll's under the .NET tab in the Add Referenced dialog. They live in the following location, or if you are on a 64-bit machine like me, it will be Program Files (x86).       C:\Program Files\Microsoft SDKs\Silverlight\v4.0\Libraries\Client Now let's create some UI for our new project. 5. First, create a new Silverlight User Control called Page3.dyn.xaml 6. Paste the following code into the xaml: <dyn:DynamicPageShim xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     xmlns:my="clr-namespace:Page3;assembly=Page3">     <my:Page3Host /> </dyn:DynamicPageShim> This is just a 'shim', part of David Poll's technique for dynamic loading. 7. Expand the icon next to Page3.dyn.xaml and delete the code-behind file (Page3.dyn.xaml.cs). 8. Next we will create a control that will 'host' our page. Create another Silverlight User Control called Page3Host.xaml and paste in the following XAML: <dyn:DynamicPage x:Class="Page3.Page3Host"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     xmlns:Views="clr-namespace:Page3.Views"      mc:Ignorable="d"     d:DesignHeight="300" d:DesignWidth="400"     Title="Page 3">       <Views:Page3/>   </dyn:DynamicPage> 9. Now paste the following code into the code-behind for this control: using DynamicXAPLoading.Infrastructure;   namespace Page3 {     [PageMetadata(NavigateUri = "/Page3;component/Page3.dyn.xaml", Module = Enums.Page3)]     public partial class Page3Host     {         public Page3Host()         {             InitializeComponent();         }     } } Notice that we are now using that PageMetadata custom attribute class that we created in the Infrastructure project, and setting its two properties. NavigateUri - This tells it that the assembly is called Page3 (with a slash beforehand), and the page we want to load is Page3.dyn.xaml...our 'shim'. That line we added to the UriMapper in MainPage.xaml will use this information to load the page. Module - This goes back to that ModuleEnum class in our Infrastructure project. However, setting the Module to ModuleEnum.Page3 will cause a compilation error, so... 10. Go back to that Enums.cs under the Infrastructure project and add a 3rd entry for Page3: public enum ModuleEnum {     Page1,     Page2,     Page3 } 11. Now right-click on the Page3 project and add a folder called Views. 12. Right-click on the Views folder and create a new Silverlight User Control called Page3.xaml. We won't bother creating a view model for this User Control as I did in the Page 1 and Page 2 projects, just for the sake of simplicity. Feel free to add one if you'd like though, and copy the code from one of those other projects. Right now those view models aren't really doing anything anyway...though they will in my next post. :-) 13. Now let's replace the xaml for Page3.xaml with the following: <dyn:DynamicPage x:Class="Page3.Views.Page3"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     mc:Ignorable="d"     d:DesignHeight="300" d:DesignWidth="400"     Style="{StaticResource PageStyle}">       <Grid x:Name="LayoutRoot">         <ScrollViewer x:Name="PageScrollViewer" Style="{StaticResource PageScrollViewerStyle}">             <StackPanel x:Name="ContentStackPanel">                 <TextBlock x:Name="HeaderText" Style="{StaticResource HeaderTextStyle}" Text="Page 3"/>                 <TextBlock x:Name="ContentText" Style="{StaticResource ContentTextStyle}" Text="Page 3 content"/>             </StackPanel>         </ScrollViewer>     </Grid>   </dyn:DynamicPage> 14. And in the code-behind remove the inheritance from UserControl, so it should look like this: namespace Page3.Views {     public partial class Page3     {         public Page3()         {             InitializeComponent();         }     } } One thing you may have noticed is that the base class for the last two User Controls we created is DynamicPage. Once again, we are using the infrastructure that David Poll created. 15. OK, a few last things. We need a link on our main page so that we can access our new page. In MainPage.xaml let's update our links to look like this: <StackPanel x:Name="LinksStackPanel" Style="{StaticResource LinksStackPanelStyle}">     <HyperlinkButton Style="{StaticResource LinkStyle}" NavigateUri="/Home" TargetName="ContentFrame" Content="home"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 1" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage1}"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 2" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage2}"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 3" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage3}"/> </StackPanel> 16. Next, we need to add the following at the bottom of MainPageViewModel in the ViewModels directory of our DynamicXAPLoading project: public ModuleEnum ModulePage3 {     get { return ModuleEnum.Page3; } } 17. And at last, we need to add a case for our new page to the switch statement in MainPageViewModel: switch (module) {     case ModuleEnum.Page1:         DownloadPackage("Page1.xap");         break;     case ModuleEnum.Page2:         DownloadPackage("Page2.xap");         break;     case ModuleEnum.Page3:         DownloadPackage("Page3.xap");         break;     default:         break; } Now fire up the application and click the page 1, page 2 and page 3 links. What you'll notice is that there is a 2-second delay the first time you hit each page. That is because I added the following line to the Navigate method in MainPageViewModel: Thread.Sleep(2000); // Simulate a 2 second initial loading delay The reason I put this in there is that I wanted to simulate a delay the first time the page loads (as the .xap is being downloaded from the server). You'll notice that after the first hit to the page though that there is no delay...that's because the .xap has already been downloaded. Feel free to comment out this 2-second delay, or remove it if you'd like. I just wanted to show how subsequent hits to the page would be quicker than the initial one. By the way, you may want to display some sort of BusyIndicator while the .xap is loading. I have that in my Task-It appplication, but for the sake of simplicity I did not include it here. In the future I'll blog about how I show and hide the BusyIndicator using events (I'm currently using the eventing framework in Prism for that, but may move to the one in the MVVM Light Toolkit some time soon). Whew, that felt like a lot of steps, but it does work quite nicely. As I mentioned earlier, I'll try to find ways to simplify the code (I'd like to get away from having things like hard-coded .xap file names) and will blog about it in the future if I find a better way. In my next post, I'll talk more about what is actually happening with the code that makes this all work.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • SQLAuthority News – SQL Server Technical Article – The Data Loading Performance Guide

    - by pinaldave
    The white paper describes load strategies for achieving high-speed data modifications of a Microsoft SQL Server database. “Bulk Load Methods” and “Other Minimally Logged and Metadata Operations” provide an overview of two key and interrelated concepts for high-speed data loading: bulk loading and metadata operations. After this background knowledge, white paper describe how these methods can be [...]

    Read the article

  • Determining cause of random latency and loading issues

    - by Sherwin Flight
    I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of CSS and JS files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well.

    Read the article

  • Determining cause of random latency/loading issues

    - by Sherwin Flight
    I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of css/js files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well. Any help or advice is much appreciated.

    Read the article

  • Managed game frameworks with Model loading support [on hold]

    - by codymanix
    Iam looking for an alternative to XNA with support of model loading. Does anybody know when/if there if a MonoGame release is planned which includes its own content pipeline which works without XNA beeing installed? If not, what are the alternatives in managed game development? As far as I know, SlimDX and SharpDX on its own brings no functionality for loading models. Are there any open source libraries that can do that?

    Read the article

  • Shadow mapping with deffered shading for directional lights - shadow map projection problem

    - by Harry
    I'm trying to implement shadow mapping to my engine. I started with directional lights because they seemed to be the easiest one, but I was wrong :) I have implemented deferred shading and I retrieve position from depth. I think that there is the biggest problem but code looks ok for me. Now more about problem: Shadow map projected onto meshes looks bad scaled and translated and also some informations from shadow map texture aren't visible. You can see it on this screen: http://img5.imageshack.us/img5/2254/93dn.png Yelow frustum is light frustum and I have mixed shadow map preview and actual scene. As you can see shadows are in wrong place and shadow of cone and sphere aren't visible. Could you look at my codes and tell me where I have a mistake? // create shadow map if(!_shd)glGenTextures(1, &_shd); glBindTexture(GL_TEXTURE_2D, _shd); glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 1024, 1024, 0, GL_DEPTH_COMPONENT, GL_FLOAT,NULL); // shadow map size glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, _shd, 0); glDrawBuffer(GL_NONE); // setting camera Vector dire=Vector(0,0,1); ACamera.setLookAt(dire,Vector(0)); ACamera.setPerspectiveView(60.0f,1,0.1f,10.0f); // currently needed for proper frustum corners calculation Vector min(ACamera._point[0]),max(ACamera._point[0]); for(int i=0;i<8;i++){ max=Max(max,ACamera._point[i]); min=Min(min,ACamera._point[i]); } ACamera.setOrthogonalView(min.x,max.x,min.y,max.y,-max.z,-min.z); glBindFramebuffer(GL_DRAW_FRAMEBUFFER, _s_buffer); // framebuffer for shadow map // rendering to depth buffer glBindFramebuffer(GL_DRAW_FRAMEBUFFER, _g_buffer); Shaders["DirLight"].set(true); Matrix4 bias; bias.x.set(0.5,0.0,0.0,0.0); bias.y.set(0.0,0.5,0.0,0.0); bias.z.set(0.0,0.0,0.5,0.0); bias.w.set(0.5,0.5,0.5,1.0); Shaders["DirLight"].set("textureMatrix",ACamera.matrix*Projection3D*bias); // order of multiplications are 100% correct, everything gives mi the same result as using glm glActiveTexture(GL_TEXTURE5); glBindTexture(GL_TEXTURE_2D,_shd); lightDir(dir); // light calculations Vertex Shader makes nothing related to shadow calculatons Pixel shader function which calculates if pixel is in shadow or not: float readShadowMap(vec3 eyeDir) { // retrieve depth of pixel float z = texture2D(depth, gl_FragCoord.xy/screen).z; vec3 pos = vec3(gl_FragCoord.xy/screen, z); // transform by the projection and view inverse vec4 worldSpace = inverse(View)*inverse(ProjectionMatrix)*vec4(pos*2-1,1); worldSpace /= worldSpace.w; vec4 coord=textureMatrix*worldSpace; float vis=1.0f; if(texture2D(shadow, coord.xy).z < coord.z-0.001)vis=0.2f; return vis; } I also have question about shadows specifically for directional light. Currently I always look at 0,0,0 position and in further implementation I have to move light frustum along to camera frustum. I've found how to do this here: http://www.gamedev.net/topic/505893-orthographic-projection-for-shadow-mapping/ but it doesn't give me what I want. Maybe because of problems mentioned above, but I want know your opinion. EDIT: vec4 worldSpace is position read from depht of the scene (not shadow map). Maybe I wasn't precise so I'll try quick explain what is what: View is camera view matrix, ProjectionMatrix is camera projection,. First I try to get world space position from depth map and then multiply it by textureMatrix which is light view *light projection*bias. Rest of code is the same as in many tutorials. I can't use vertex shader to make something like gl_Position=textureMatrix*gl_Vertex and get it interpolated in fragment shader because of deffered rendering use so I want get it from depht buffer. EDIT2: I also tried make it as in Coding Labs tutorial about Shadow Mapping with Deferred Rendering but unfortunately this either works wrong.

    Read the article

  • External table and preprocessor for loading LOBs

    - by David Allan
    I was using the COLUMN TRANSFORMS syntax to load LOBs into Oracle using the Oracle external which is a handy way of doing several stuff - from loading LOBs from the filesystem to having constants as fields. In OWB you can use unbound external tables to define an external table using your own arbitrary access parameters - I blogged a while back on this for doing preprocessing before it was added into OWB 11gR2. For loading LOBs using the COLUMN TRANSFORMS syntax have a read through this post on loading CLOB, BLOB or any LOB, the files to load can be specified as a field that is a filename field, the content of this file will be the LOB data. So using the example from the linked post, you can define the columns; Then define the access parameters - if you go the unbound external table route you can can put whatever you want in here (your external table get out of jail free card); This will let you read the LOB files fromn the filesystem and use the external table in a mapping. Pushing the envelope a little further I then thought about marrying together the preprocessor with the COLUMN TRANSFORMS, this would have let me have a shell script for example as the preprocessor which listed the contents of a directory and let me read the files as LOBs via an external table. Unfortunately that doesn't quote work - there is now a bug/enhancement logged, so one day maybe. So I'm afraid my blog title was a little bit of a teaser....

    Read the article

  • Brightness going up to 100% on loading certain websites in Chrome

    - by picheto
    I'm using Google Chrome version 21.0.1180.89 on Ubuntu 12.04 and my laptop is a Sony VAIO VPCCW15FL (spec sheet). My video driver is the propietary "NVIDIA accelerated graphics driver (post-release updates)(version-current updates)". After installing Ubuntu, I discovered that neither the brightness control buttons (hardware) or the brightness slider (software) worked, and found out I could get the hardware buttons to work by installing the nvidiabl.deb package and oBacklight script. I'm using nvidiabl-dkms 0.77 and oBacklight 0.3.8. Still, the slider on the Ubuntu "Settings" does not work, but I don't care. There is an annoying thing happening when loading certain pages in Google Chrome: the brightness goes up to 100% when loading the webpage or when leaving it (closing the tab or typing a different URL on the omnibox). However, the "brightness tooltip" (that default brightness notification) remembers the position it was set to, so if I adjust the brightness with the HW buttons, the level gets adjusted relative to the value it was set to before "going 100%". I disabled the flash PPAPI plugin, but left the NPAPI plugin enabled, and the problem went away for pages with flash content. Still, the same thing happens when viewing HTML5 video, or when loading, for example, the Chrome Web Store or using the Scratchpad extension. I suppose it has to do with the rendering of certain elements using the GPU, but this is just a guess. This brightness thing does not happen when using Firefox 15.0 or any other application I have used yet. Does anybody know why this may be happening and what could I do to fix this without changing browser? Thanks a lot.

    Read the article

  • How can I use back button while loading a page in an Android WebView?

    - by Sara
    I have a link in my application that triggers a webview to open from webview.loadUrl(...). Sometimes it's takes quite a while to load the page, and in these cases I want to be able to use the built in back button on the phone to cancel the loading and go back to my application. How do I do this? Is there some way I can listen to the backbutton while loading the url?

    Read the article

  • How can I use the dualforward parameter in my unity shader to use lightmaps and normal maps together?

    - by Raphaeltm
    I'm using the free version of unity and I would like to combine lightmaps with specularity and normal maps. After doing a -bunch- of research, I've figured out that there doesn't seem to be any easy way to do this in the free version of unity, which doesn't support deferred rendering/easy use of dual lightmaps. However, it looks like it's possible, by writing a custom shader, using the "dualforward" parameter in a shader, switching the lightmapping mode to "dual lightmaps" and turning on "Use in forward ren." (basically, writing a shader that specifies the use of dual lightmaps, which should allow for a combination of lightmaps and normal maps) So I downloaded the source code for the default shaders (because all I need is a normal specular bumped shader) and added "dualforward" to the parameters: Shader "Bumped Specular Dual Lightmaps" { Properties { _Color ("Main Color", Color) = (1,1,1,1) _SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 1) _Shininess ("Shininess", Range (0.03, 1)) = 0.078125 _MainTex ("Base (RGB) Gloss (A)", 2D) = "white" {} _BumpMap ("Normalmap", 2D) = "bump" {} } SubShader { Tags { "RenderType"="Opaque" } LOD 400 CGPROGRAM #pragma surface surf BlinnPhong dualforward sampler2D _MainTex; sampler2D _BumpMap; fixed4 _Color; half _Shininess; struct Input { float2 uv_MainTex; float2 uv_BumpMap; }; void surf (Input IN, inout SurfaceOutput o) { fixed4 tex = tex2D(_MainTex, IN.uv_MainTex); o.Albedo = tex.rgb * _Color.rgb; o.Gloss = tex.a; o.Alpha = tex.a * _Color.a; o.Specular = _Shininess; o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap)); } ENDCG } FallBack "Specular" } This, however, doesn't seem to work. When I keep the "dualforward" param, every object that uses it seems to be lit by the one directional light in the scene. When I remove the "dualforward" param, it they look like normal lightmapped objects with no normal maps or specularity. I noticed that the support for "dualforward" seems to be new in v.3.4.2, so I made sure to download it (I was running 3.4.1), but it still doesn't work. Anybody have any advice for me?

    Read the article

  • how to organize rendering

    - by Irbis
    I use a deferred rendering. During g-buffer stage my rendering loop for a sponza model (obj format) looks like this: int i = 0; int sum = 0; map<string, mtlItem *>::const_iterator itrEnd = mtl.getIteratorEnd(); for(map<string, mtlItem *>::const_iterator itr = mtl.getIteratorBegin(); itr != itrEnd; ++itr) { glActiveTexture(GL_TEXTURE0 + 0); glBindTexture(GL_TEXTURE_2D, itr->second->map_KdId); glDrawElements(GL_TRIANGLES, indicesCount[i], GL_UNSIGNED_INT, (GLvoid*)(sum * 4)); sum += indicesCount[i]; ++i; glBindTexture(GL_TEXTURE_2D, 0); } I sorted faces based on materials. I switch only a diffuse texture but I can place there more material properties. Is it a good approach ? I also wonder how to handle a different kind of materials, for example: some material use a normal map, other doesn't use. Should I have a different shaders for them ?

    Read the article

  • how to get the type of a deferred template parameter

    - by smerlin
    Is there a way to get the defered type of a class template parameter ? template <class TPtr> struct foo { typedef TPtr ptr_type; typedef ??? element_type; /* shall be the type of a deferred TPtr*/ }; so foo<const char*>::element_type results in const char, and foo<std::vector<int>::iterator_type>::element_type results in int. i am aware of that i can use the value_type typedef for c++ iterators (like std::vector<int>::iterator_type::value_type), but raw pointers havent got a value_type typedef, so i am out of luck there.

    Read the article

  • E_FAIL: An undetermined error occurred (-2147467259) when loading a cube texture

    - by Boreal
    I'm trying to implement a skybox into my engine, and I'm having some trouble loading the image as a cube map. Everything works (but it doesn't look right) if I don't load using an ImageLoadInformation struct in the ShaderResourceView.FromFile() method, but it breaks if I do. I need to, of course, because I need to tell SlimDX to load it as a cubemap. How can I fix this? Here is my new loading code after the "fix": public static void LoadCubeTexture(string filename) { ImageLoadInformation loadInfo = new ImageLoadInformation() { BindFlags = BindFlags.ShaderResource, CpuAccessFlags = CpuAccessFlags.None, Depth = 32, FilterFlags = FilterFlags.None, FirstMipLevel = 0, Format = SlimDX.DXGI.Format.B8G8R8A8_UNorm, Height = 512, MipFilterFlags = FilterFlags.Linear, MipLevels = 1, OptionFlags = ResourceOptionFlags.TextureCube, Usage = ResourceUsage.Default, Width = 512 }; textures.Add(filename, ShaderResourceView.FromFile(Graphics.device, "Resources/" + filename, loadInfo)); } Each of the faces of my cube texture are 512x512.

    Read the article

  • E_INVALIDARG: An invalid parameter was passed to the returning function (-2147024809) when loading a cube texture

    - by Boreal
    I'm trying to implement a skybox into my engine, and I'm having some trouble loading the image as a cube map. Everything works (but it doesn't look right) if I don't load using an ImageLoadInformation struct in the ShaderResourceView.FromFile() method, but it breaks if I do. I need to, of course, because I need to tell SlimDX to load it as a cubemap. How can I fix this? Here is my new loading code after the "fix": public static void LoadCubeTexture(string filename) { ImageLoadInformation loadInfo = ImageLoadInformation.FromDefaults(); loadInfo.OptionFlags = ResourceOptionFlags.TextureCube; textures.Add(filename, ShaderResourceView.FromFile(Graphics.device, "Resources/" + filename, loadInfo)); }

    Read the article

  • Parallel Classloading Revisited: Fully Concurrent Loading

    - by davidholmes
    Java 7 introduced support for parallel classloading. A description of that project and its goals can be found here: http://openjdk.java.net/groups/core-libs/ClassLoaderProposal.html The solution for parallel classloading was to add to each class loader a ConcurrentHashMap, referenced through a new field, parallelLockMap. This contains a mapping from class names to Objects to use as a classloading lock for that class name. This was then used in the following way: protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException { synchronized (getClassLoadingLock(name)) { // First, check if the class has already been loaded Class c = findLoadedClass(name); if (c == null) { long t0 = System.nanoTime(); try { if (parent != null) { c = parent.loadClass(name, false); } else { c = findBootstrapClassOrNull(name); } } catch (ClassNotFoundException e) { // ClassNotFoundException thrown if class not found // from the non-null parent class loader } if (c == null) { // If still not found, then invoke findClass in order // to find the class. long t1 = System.nanoTime(); c = findClass(name); // this is the defining class loader; record the stats sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0); sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); sun.misc.PerfCounter.getFindClasses().increment(); } } if (resolve) { resolveClass(c); } return c; } } Where getClassLoadingLock simply does: protected Object getClassLoadingLock(String className) { Object lock = this; if (parallelLockMap != null) { Object newLock = new Object(); lock = parallelLockMap.putIfAbsent(className, newLock); if (lock == null) { lock = newLock; } } return lock; } This approach is very inefficient in terms of the space used per map and the number of maps. First, there is a map per-classloader. As per the code above under normal delegation the current classloader creates and acquires a lock for the given class, checks if it is already loaded, then asks its parent to load it; the parent in turn creates another lock in its own map, checks if the class is already loaded and then delegates to its parent and so on till the boot loader is invoked for which there is no map and no lock. So even in the simplest of applications, you will have two maps (in the system and extensions loaders) for every class that has to be loaded transitively from the application's main class. If you knew before hand which loader would actually load the class the locking would only need to be performed in that loader. As it stands the locking is completely unnecessary for all classes loaded by the boot loader. Secondly, once loading has completed and findClass will return the class, the lock and the map entry is completely unnecessary. But as it stands, the lock objects and their associated entries are never removed from the map. It is worth understanding exactly what the locking is intended to achieve, as this will help us understand potential remedies to the above inefficiencies. Given this is the support for parallel classloading, the class loader itself is unlikely to need to guard against concurrent load attempts - and if that were not the case it is likely that the classloader would need a different means to protect itself rather than a lock per class. Ultimately when a class file is located and the class has to be loaded, defineClass is called which calls into the VM - the VM does not require any locking at the Java level and uses its own mutexes for guarding its internal data structures (such as the system dictionary). The classloader locking is primarily needed to address the following situation: if two threads attempt to load the same class, one will initiate the request through the appropriate loader and eventually cause defineClass to be invoked. Meanwhile the second attempt will block trying to acquire the lock. Once the class is loaded the first thread will release the lock, allowing the second to acquire it. The second thread then sees that the class has now been loaded and will return that class. Neither thread can tell which did the loading and they both continue successfully. Consider if no lock was acquired in the classloader. Both threads will eventually locate the file for the class, read in the bytecodes and call defineClass to actually load the class. In this case the first to call defineClass will succeed, while the second will encounter an exception due to an attempted redefinition of an existing class. It is solely for this error condition that the lock has to be used. (Note that parallel capable classloaders should not need to be doing old deadlock-avoidance tricks like doing a wait() on the lock object\!). There are a number of obvious things we can try to solve this problem and they basically take three forms: Remove the need for locking. This might be achieved by having a new version of defineClass which acts like defineClassIfNotPresent - simply returning an existing Class rather than triggering an exception. Increase the coarseness of locking to reduce the number of lock objects and/or maps. For example, using a single shared lockMap instead of a per-loader lockMap. Reduce the lifetime of lock objects so that entries are removed from the map when no longer needed (eg remove after loading, use weak references to the lock objects and cleanup the map periodically). There are pros and cons to each of these approaches. Unfortunately a significant "con" is that the API introduced in Java 7 to support parallel classloading has essentially mandated that these locks do in fact exist, and they are accessible to the application code (indirectly through the classloader if it exposes them - which a custom loader might do - and regardless they are accessible to custom classloaders). So while we can reason that we could do parallel classloading with no locking, we can not implement this without breaking the specification for parallel classloading that was put in place for Java 7. Similarly we might reason that we can remove a mapping (and the lock object) because the class is already loaded, but this would again violate the specification because it can be reasoned that the following assertion should hold true: Object lock1 = loader.getClassLoadingLock(name); loader.loadClass(name); Object lock2 = loader.getClassLoadingLock(name); assert lock1 == lock2; Without modifying the specification, or at least doing some creative wordsmithing on it, options 1 and 3 are precluded. Even then there are caveats, for example if findLoadedClass is not atomic with respect to defineClass, then you can have concurrent calls to findLoadedClass from different threads and that could be expensive (this is also an argument against moving findLoadedClass outside the locked region - it may speed up the common case where the class is already loaded, but the cost of re-executing after acquiring the lock could be prohibitive. Even option 2 might need some wordsmithing on the specification because the specification for getClassLoadingLock states "returns a dedicated object associated with the specified class name". The question is, what does "dedicated" mean here? Does it mean unique in the sense that the returned object is only associated with the given class in the current loader? Or can the object actually guard loading of multiple classes, possibly across different class loaders? So it seems that changing the specification will be inevitable if we wish to do something here. In which case lets go for something that more cleanly defines what we want to be doing: fully concurrent class-loading. Note: defineClassIfNotPresent is already implemented in the VM as find_or_define_class. It is only used if the AllowParallelDefineClass flag is set. This gives us an easy hook into existing VM mechanics. Proposal: Fully Concurrent ClassLoaders The proposal is that we expand on the notion of a parallel capable class loader and define a "fully concurrent parallel capable class loader" or fully concurrent loader, for short. A fully concurrent loader uses no synchronization in loadClass and the VM uses the "parallel define class" mechanism. For a fully concurrent loader getClassLoadingLock() can return null (or perhaps not - it doesn't matter as we won't use the result anyway). At present we have not made any changes to this method. All the parallel capable JDK classloaders become fully concurrent loaders. This doesn't require any code re-design as none of the mechanisms implemented rely on the per-name locking provided by the parallelLockMap. This seems to give us a path to remove all locking at the Java level during classloading, while retaining full compatibility with Java 7 parallel capable loaders. Fully concurrent loaders will still encounter the performance penalty associated with concurrent attempts to find and prepare a class's bytecode for definition by the VM. What this penalty is depends on the number of concurrent load attempts possible (a function of the number of threads and the application logic, and dependent on the number of processors), and the costs associated with finding and preparing the bytecodes. This obviously has to be measured across a range of applications. Preliminary webrevs: http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.hotspot/ http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.jdk/ Please direct all comments to the mailing list [email protected].

    Read the article

  • Problem in Loading certain Websites in Ubuntu 11.10

    - by Cody
    I have a DSL connection in Ubuntu 11.04 and am having problems loading content from certain websites mostly providing CDN services. I have tried every suggestion asked at problem loading internet pages as I have the same problem. Also tried to remove the DNS Cache and Browser Cache. I have tried using Google DNS Server: 8.8.8.8 and 8.8.4.4, but nothing seems to work. Though when I browse the websites in Windows XP then it does not pose any problem. This problem has come up only few days ago and has affected every browser(Chrome, Firefox and Opera) in Ubuntu 11.04. Thanks in advance.

    Read the article

  • Explicit resource loading in Ogre (Mogre)

    - by sebf
    I am just starting to learn Mogre and what I would like to do is to be able to load resources 'explicitly' (i.e. I just provide an absolute path instead of using a resource group tied to a directory). This is very different to manually loading resources, which I believe in Ogre has a very specific meaning, to build up the object using Ogres methods. I want to use Ogres resource management system/resource loading code, but to have finer control over which files are loaded and in what groups they are. I remember reading how to do this but cannot find the page again; I think its possible to do something like: Declare a resource group Declare the resource(s) (this is when the actual resource file name is provided) Initialise the resource group to actually load the resource(s) Is this the correct procedure? If so, is there any example code showing how to do this?

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 4 5 6 7 8 9 10 11 12 13 14 15  | Next Page >