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• How to explain traits?

  - by Partial

  How would you explain traits to a new C++ programmer? How would you explain traits to a C programmer? How would you explain traits to a Java/Ruby/Python/C# or any other OOP language programmer?

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• C#: Oracle Data Type Equivalence with OracleDbType

  - by Partial

  Situation: I am creating an app in C# that uses Oracle.DataAccess.Client (11g) to do certain operations on a Oracle database with stored procedures. I am aware that there is a certain enum (OracleDbType) that contains the Oracle data types, but I am not sure which one to use for certain types. Questions: What is the equivalent Oracle PL/SQL data type for each enumerated type in the OracleDbType enumeration? There are three types of integer (Int16, Int32, Int64) in the OracleDbType... how to know which one to use or are they all suppose to work?

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• ASP.NET exception gives irrelevant stack trace on YSOD, very challenging!

  - by pootow

  Here is the YSOD: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.] System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +428 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 ECommerce.PMethod.Sql.SqlConns.Open() +78 ECommerce.PMethod.Sql.SqlConns..ctor() +120 ECommerce.login.DatasInfo.Proc.UserCenter.IsLogin(String UserGUID, Int32 UserID) +49 ECommerce.login.Rules.Users.UserLogin.isLogin() +44 Config.isUserLogined() +5 Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 [TypeInitializationException: The type initializer for 'ECommerce.ERP.DAL.DBConn' threw an exception.] ECommerce.ERP.DAL.DBConn.get_ConnString() +0 [ObjectDefinitionStoreException: Factory method 'System.String get_ConnString()' threw an Exception.] Spring.Objects.Factory.Support.SimpleInstantiationStrategy.Instantiate(RootObjectDefinition definition, String name, IObjectFactory factory, MethodInfo factoryMethod, Object[] arguments) +257 Spring.Objects.Factory.Support.ConstructorResolver.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +624 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +60 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +56 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +436 [ObjectCreationException: Error thrown by a dependency of object 'styleService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 56' : Initialization of object failed : Factory method 'System.String get_ConnString()' threw an Exception. while resolving 'constructor argument with name promotionservice' to 'promotionService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 31' while resolving 'constructor argument with name domainservice' to 'promotionDomainService' defined in 'assembly [ECommerce.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Domain.AppContext.xml] line 20' while resolving 'constructor argument with name promotionrepos' to 'promotionRepos' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34' while resolving 'constructor argument with name connstr' to 'ECommerce.ERP.DAL.DBConn#389F399' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveReference(IObjectDefinition definition, String name, String argumentName, RuntimeObjectReference reference) +394 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +312 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +17 Spring.Objects.Factory.Support.ConstructorResolver.ResolveConstructorArguments(String objectName, RootObjectDefinition definition, ObjectWrapper wrapper, ConstructorArgumentValues cargs, ConstructorArgumentValues resolvedValues) +993 Spring.Objects.Factory.Support.ConstructorResolver.AutowireConstructor(String objectName, RootObjectDefinition rod, ConstructorInfo[] chosenCtors, Object[] explicitArgs) +171 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.AutowireConstructor(String name, RootObjectDefinition definition, ConstructorInfo[] ctors, Object[] explicitArgs) +65 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +161 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +636 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +174 Spring.Objects.Factory.Support.WebObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +150 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) +990 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObject(String name) +10 Spring.Context.Support.AbstractApplicationContext.GetObject(String name) +20 ECommerce.Common.ServiceLocator.GetService() +334 ECommerce.Mvc.Controllers.StylesController..ctor() +72 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80 [InvalidOperationException: An error occurred when trying to create a controller of type 'ECommerce.Mvc.Controllers.StylesController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +190 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +68 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +118 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +46 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +63 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +13 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677954 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Question is: the first stack trace is irrelevant to others, what happened? Any ideas? Let me make this more clear: a MVC page uses the spring part trying to load a lazy-init service which constructor wants a connection string through a static property like this: <object id="promotionRepos" type="ECommerce.Data.AdoNet.Promotions.PromotionRepos, ECommerce.Data.AdoNet" lazy-init="true"> <constructor-arg name="provider"> <null /> </constructor-arg> <constructor-arg name="connStr"> <object type="ECommerce.ERP.DAL.DBConn, ECommerce.ERP.DAL" factory-method="get_ConnString" /> </constructor-arg> <property name="RefreshInterval" value="00:00:10" /> </object> the timeout part is some what irrelevent to all others. see this in the first exception: Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 it's another page at all. And also, ECommerce.PMethod.Sql.SqlConns.Open() uses its own connection string, not the one loaded by spring, it's different module from diffrent team. And I am sure the connection string is correct. And, this ysod cames up randomly. Sometimes nothing is wrong, and sometimes, it appears. I thought there could be something wrong with my database or the network/firewall, I will check it later, but now I want understand this tricky stack trace.

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• Automating deployments with the SQL Compare command line

  - by Jonathan Hickford

  In my previous article, “Five Tips to Get Your Organisation Releasing Software Frequently” I looked at how teams can automate processes to speed up release frequency. In this post, I’m looking specifically at automating deployments using the SQL Compare command line. SQL Compare compares SQL Server schemas and deploys the differences. It works very effectively in scenarios where only one deployment target is required – source and target databases are specified, compared, and a change script is automatically generated and applied. But if multiple targets exist, and pressure to increase the frequency of releases builds, this solution quickly becomes unwieldy.   This is where SQL Compare’s command line comes into its own. I’ve put together a PowerShell script that loops through the Servers table and pulls out the server and database, these are then passed to sqlcompare.exe to be used as target parameters. In the example the source database is a scripts folder, a folder structure of scripted-out database objects used by both SQL Source Control and SQL Compare. The script can easily be adapted to use schema snapshots.     -- Create a DeploymentTargets database and a Servers table CREATE DATABASE DeploymentTargets GO USE DeploymentTargets GO CREATE TABLE [dbo].[Servers]( [id] [int] IDENTITY(1,1) NOT NULL, [serverName] [nvarchar](50) NULL, [environment] [nvarchar](50) NULL, [databaseName] [nvarchar](50) NULL, CONSTRAINT [PK_Servers] PRIMARY KEY CLUSTERED ([id] ASC) ) GO -- Now insert your target server and database details INSERT INTO dbo.Servers ( serverName , environment , databaseName) VALUES ( N'myserverinstance' , N'myenvironment1' , N'mydb1') INSERT INTO dbo.Servers ( serverName , environment , databaseName) VALUES ( N'myserverinstance' , N'myenvironment2' , N'mydb2') Here’s the PowerShell script you can adapt for yourself as well. # We're holding the server names and database names that we want to deploy to in a database table. # We need to connect to that server to read these details $serverName = "" $databaseName = "DeploymentTargets" $authentication = "Integrated Security=SSPI" #$authentication = "User Id=xxx;PWD=xxx" # If you are using database authentication instead of Windows authentication. # Path to the scripts folder we want to deploy to the databases $scriptsPath = "SimpleTalk" # Path to SQLCompare.exe $SQLComparePath = "C:\Program Files (x86)\Red Gate\SQL Compare 10\sqlcompare.exe" # Create SQL connection string, and connection $ServerConnectionString = "Data Source=$serverName;Initial Catalog=$databaseName;$authentication" $ServerConnection = new-object system.data.SqlClient.SqlConnection($ServerConnectionString); # Create a Dataset to hold the DataTable $dataSet = new-object "System.Data.DataSet" "ServerList" # Create a query $query = "SET NOCOUNT ON;" $query += "SELECT serverName, environment, databaseName " $query += "FROM dbo.Servers; " # Create a DataAdapter to populate the DataSet with the results $dataAdapter = new-object "System.Data.SqlClient.SqlDataAdapter" ($query, $ServerConnection) $dataAdapter.Fill($dataSet) | Out-Null # Close the connection $ServerConnection.Close() # Populate the DataTable $dataTable = new-object "System.Data.DataTable" "Servers" $dataTable = $dataSet.Tables[0] #For every row in the DataTable $dataTable | FOREACH-OBJECT { "Server Name: $($_.serverName)" "Database Name: $($_.databaseName)" "Environment: $($_.environment)" # Compare the scripts folder to the database and synchronize the database to match # NB. Have set SQL Compare to abort on medium level warnings. $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/AbortOnWarnings:Medium") # + @("/sync" ) # Commented out the 'sync' parameter for safety, write-host $arguments & $SQLComparePath $arguments "Exit Code: $LASTEXITCODE" # Some interesting variations # Check that every database matches a folder. # For example this might be a pre-deployment step to validate everything is at the same baseline state. # Or a post deployment script to validate the deployment worked. # An exit code of 0 means the databases are identical. # # $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/Assertidentical") # Generate a report of the difference between the folder and each database. Generate a SQL update script for each database. # For example use this after the above to generate upgrade scripts for each database # Examine the warnings and the HTML diff report to understand how the script will change objects # #$arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/ScriptFile:update_$($_.environment+"_"+$_.databaseName).sql", "/report:update_$($_.environment+"_"+$_.databaseName).html" , "/reportType:Interactive", "/showWarnings", "/include:Identical") } It’s worth noting that the above example generates the deployment scripts dynamically. This approach should be problem-free for the vast majority of changes, but it is still good practice to review and test a pre-generated deployment script prior to deployment. An alternative approach would be to pre-generate a single deployment script using SQL Compare, and run this en masse to multiple targets programmatically using sqlcmd, or using a tool like SQL Multi Script.  You can use the /ScriptFile, /report, and /showWarnings flags to generate change scripts, difference reports and any warnings.  See the commented out example in the PowerShell: #$arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/ScriptFile:update_$($_.environment+"_"+$_.databaseName).sql", "/report:update_$($_.environment+"_"+$_.databaseName).html" , "/reportType:Interactive", "/showWarnings", "/include:Identical") There is a drawback of running a pre-generated deployment script; it assumes that a given database target hasn’t drifted from its expected state. Often there are (rightly or wrongly) many individuals within an organization who have permissions to alter the production database, and changes can therefore be made outside of the prescribed development processes. The consequence is that at deployment time, the applied script has been validated against a target that no longer represents reality. The solution here would be to add a check for drift prior to running the deployment script. This is achieved by using sqlcompare.exe to compare the target against the expected schema snapshot using the /Assertidentical flag. Should this return any differences (sqlcompare.exe Exit Code 79), a drift report is outputted instead of executing the deployment script.  See the commented out example. # $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/Assertidentical") Any checks and processes that should be undertaken prior to a manual deployment, should also be happen during an automated deployment. You might think about triggering backups prior to deployment – even better, automate the verification of the backup too.   You can use SQL Compare’s command line interface along with PowerShell to automate multiple actions and checks that you need in your deployment process. Automation is a practical solution where multiple targets and a higher release cadence come into play. As we know, with great power comes great responsibility – responsibility to ensure that the necessary checks are made so deployments remain trouble-free.  (The code sample supplied in this post automates the simple dynamic deployment case – if you are considering more advanced automation, e.g. the drift checks, script generation, deploying to large numbers of targets and backup/verification, please email me at [email protected] for further script samples or if you have further questions)

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• General Purpose ASP.NET Data Source Control

  - by Ricardo Peres

  OK, you already know about the ObjectDataSource control, so what’s wrong with it? Well, for once, it doesn’t pass any context to the SelectMethod, you only get the parameters supplied on the SelectParameters plus the desired ordering, starting page and maximum number of rows to display. Also, you must have two separate methods, one for actually retrieving the data, and the other for getting the total number of records (SelectCountMethod). Finally, you don’t get a chance to alter the supplied data before you bind it to the target control. I wanted something simple to use, and more similar to ASP.NET 4.5, where you can have the select method on the page itself, so I came up with CustomDataSource. Here’s how to use it (I chose a GridView, but it works equally well with any regular data-bound control): 1: <web:CustomDataSourceControl runat="server" ID="datasource" PageSize="10" OnData="OnData" /> 2: <asp:GridView runat="server" ID="grid" DataSourceID="datasource" DataKeyNames="Id" PageSize="10" AllowPaging="true" AllowSorting="true" /> The OnData event handler receives a DataEventArgs instance, which contains some properties that describe the desired paging location and size, and it’s where you return the data plus the total record count. Here’s a quick example: 1: protected void OnData(object sender, DataEventArgs e) 2: { 3: //just return some data 4: var data = Enumerable.Range(e.StartRowIndex, e.PageSize).Select(x => new { Id = x, Value = x.ToString(), IsPair = ((x % 2) == 0) }); 5: e.Data = data; 6: //the total number of records 7: e.TotalRowCount = 100; 8: } Here’s the code for the DataEventArgs: 1: [Serializable] 2: public class DataEventArgs : EventArgs 3: { 4: public DataEventArgs(Int32 pageSize, Int32 startRowIndex, String sortExpression, IOrderedDictionary parameters) 5: { 6: this.PageSize = pageSize; 7: this.StartRowIndex = startRowIndex; 8: this.SortExpression = sortExpression; 9: this.Parameters = parameters; 10: } 11:  12: public IEnumerable Data 13: { 14: get; 15: set; 16: } 17:  18: public IOrderedDictionary Parameters 19: { 20: get; 21: private set; 22: } 23:  24: public String SortExpression 25: { 26: get; 27: private set; 28: } 29:  30: public Int32 StartRowIndex 31: { 32: get; 33: private set; 34: } 35:  36: public Int32 PageSize 37: { 38: get; 39: private set; 40: } 41:  42: public Int32 TotalRowCount 43: { 44: get; 45: set; 46: } 47: } As you can guess, the StartRowIndex and PageSize receive the starting row and the desired page size, where the page size comes from the PageSize property on the markup. There’s also a SortExpression, which gets passed the sorted-by column and direction (if descending) and a dictionary containing all the values coming from the SelectParameters collection, if any. All of these are read only, and it is your responsibility to fill in the Data and TotalRowCount. The code for the CustomDataSource is very simple: 1: [NonVisualControl] 2: public class CustomDataSourceControl : DataSourceControl 3: { 4: public CustomDataSourceControl() 5: { 6: this.SelectParameters = new ParameterCollection(); 7: } 8:  9: protected override DataSourceView GetView(String viewName) 10: { 11: return (new CustomDataSourceView(this, viewName)); 12: } 13:  14: internal void GetData(DataEventArgs args) 15: { 16: this.OnData(args); 17: } 18:  19: protected virtual void OnData(DataEventArgs args) 20: { 21: EventHandler<DataEventArgs> data = this.Data; 22:  23: if (data != null) 24: { 25: data(this, args); 26: } 27: } 28:  29: [Browsable(false)] 30: [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)] 31: [PersistenceMode(PersistenceMode.InnerProperty)] 32: public ParameterCollection SelectParameters 33: { 34: get; 35: private set; 36: } 37:  38: public event EventHandler<DataEventArgs> Data; 39:  40: public Int32 PageSize 41: { 42: get; 43: set; 44: } 45: } Also, the code for the accompanying internal – as there is no need to use it from outside of its declaring assembly - data source view: 1: sealed class CustomDataSourceView : DataSourceView 2: { 3: private readonly CustomDataSourceControl dataSourceControl = null; 4:  5: public CustomDataSourceView(CustomDataSourceControl dataSourceControl, String viewName) : base(dataSourceControl, viewName) 6: { 7: this.dataSourceControl = dataSourceControl; 8: } 9:  10: public override Boolean CanPage 11: { 12: get 13: { 14: return (true); 15: } 16: } 17:  18: public override Boolean CanRetrieveTotalRowCount 19: { 20: get 21: { 22: return (true); 23: } 24: } 25:  26: public override Boolean CanSort 27: { 28: get 29: { 30: return (true); 31: } 32: } 33:  34: protected override IEnumerable ExecuteSelect(DataSourceSelectArguments arguments) 35: { 36: IOrderedDictionary parameters = this.dataSourceControl.SelectParameters.GetValues(HttpContext.Current, this.dataSourceControl); 37: DataEventArgs args = new DataEventArgs(this.dataSourceControl.PageSize, arguments.StartRowIndex, arguments.SortExpression, parameters); 38:  39: this.dataSourceControl.GetData(args); 40:  41: arguments.TotalRowCount = args.TotalRowCount; 42: arguments.MaximumRows = this.dataSourceControl.PageSize; 43: arguments.AddSupportedCapabilities(DataSourceCapabilities.Page | DataSourceCapabilities.Sort | DataSourceCapabilities.RetrieveTotalRowCount); 44: arguments.RetrieveTotalRowCount = true; 45:  46: if (!(args.Data is ICollection)) 47: { 48: return (args.Data.OfType<Object>().ToList()); 49: } 50: else 51: { 52: return (args.Data); 53: } 54: } 55: } As always, looking forward to hearing from you!

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• Part 14: Execute a PowerShell script

  In the series the following parts have been published Part 1: Introduction Part 2: Add arguments and variables Part 3: Use more complex arguments Part 4: Create your own activity Part 5: Increase AssemblyVersion Part 6: Use custom type for an argument Part 7: How is the custom assembly found Part 8: Send information to the build log Part 9: Impersonate activities (run under other credentials) Part 10: Include Version Number in the Build Number Part 11: Speed up opening my build process template Part 12: How to debug my custom activities Part 13: Get control over the Build Output Part 14: Execute a PowerShell script Part 15: Fail a build based on the exit code of a console application With PowerShell you can add powerful scripting to your build to for example execute a deployment. If you want more information on PowerShell, please refer to http://technet.microsoft.com/en-us/library/aa973757.aspx For this example we will create a simple PowerShell script that prints “Hello world!”. To create the script, create a new text file and name it “HelloWorld.ps1”. Add to the contents of the script: Write-Host “Hello World!” To test the script do the following: Open the command prompt To run the script you must change the execution policy. To do this execute in the command prompt: powershell set-executionpolicy remotesigned Now go to the directory where you have saved the PowerShell script Execute the following command powershell .\HelloWorld.ps1 In this example I use a relative path, but when the path to the PowerShell script contains spaces, you need to change the syntax to powershell "& '<full path to script>' " for example: powershell "& ‘C:\sources\Build Customization\SolutionToBuild\PowerShell Scripts\HellloWorld.ps1’ " In this blog post, I create a new solution and that solution includes also this PowerShell script. I want to create an argument on the Build Process Template that holds the path to the PowerShell script. In the Build Process Template I will add an InvokeProcess activity to execute the PowerShell command. This InvokeProcess activity needs the location of the script as an argument for the PowerShell command. Since you don’t know the full path at the build server of this script, you can either specify in the argument the relative path of the script, but it is hard to find out what the relative path is. I prefer to specify the location of the script in source control and then convert that server path to a local path. To do this conversion you can use the ConvertWorkspaceItem activity. So to complete the task, open the Build Process Template CustomTemplate.xaml that we created in earlier parts, follow the following steps Add a new argument called “DeploymentScript” and set the appropriate settings in the metadata. See Part 2: Add arguments and variables  for more information. Scroll down beneath the TryCatch activity called “Try Compile, Test, and Associate Changesets and Work Items” Add a new If activity and set the condition to "Not String.IsNullOrEmpty(DeploymentScript)" to ensure it will only run when the argument is passed. Add in the Then branch of the If activity a new Sequence activity and rename it to “Start deployment” Click on the activity and add a new variable called DeploymentScriptFilename (scoped to the “Start deployment” Sequence Add a ConvertWorkspaceItem activity on the “Start deployment” Sequence Add a InvokeProcess activity beneath the ConvertWorkspaceItem activity in the “Start deployment” Sequence Click on the ConvertWorkspaceItem activity and change the properties DisplayName = Convert deployment script filename Input = DeploymentScript Result = DeploymentScriptFilename Workspace = Workspace Click on the InvokeProcess activity and change the properties Arguments = String.Format(" ""& '{0}' "" ", DeploymentScriptFilename) DisplayName = Execute deployment script FileName = "PowerShell" To see results from the powershell command drop a WriteBuildMessage activity on the "Handle Standard Output" and pass the stdOutput variable to the Message property. Do the same for a WriteBuildError activity on the "Handle Error Output" To publish it, check in the Build Process Template This leads to the following result We now go to the build definition that depends on the template and set the path of the deployment script to the server path to the HelloWorld.ps1. (If you want to see the result of the PowerShell script, change the Logging verbosity to Detailed or Diagnostic). Save and run the build. A lot of the deployment scripts you have will have some kind of arguments (like username / password or environment variables) that you want to define in the Build Definition. To make the PowerShell configurable, you can follow the following steps. Create a new script and give it the name "HelloWho.ps1". In the contents of the file add the following lines: param (         $person     ) $message = [System.String]::Format(“Hello {0}!", $person) Write-Host $message When you now run the script on the command prompt, you will see the following So lets change the Build Process Template to accept one parameter for the deployment script. You can of course make it configurable to add a for-loop that reads through a collection of parameters but that is out of scope of this blog post. Add a new Argument called DeploymentScriptParameter In the InvokeProcess activity where the PowerShell command is executed, modify the Arguments property to String.Format(" ""& '{0}' '{1}' "" ", DeploymentScriptFilename, DeploymentScriptParameter) Check in the Build Process Template Now modify the build definition and set the Parameter of the deployment to any value and run the build. You can download the full solution at BuildProcess.zip. It will include the sources of every part and will continue to evolve.

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• Silverlight Cream Top Posted Authors June to November, 2010

  - by Dave Campbell

  It's just past the first of December, but I've been busy and it's now time to recognize devs that have a large number of posts in Silverlight Cream. Ground Rules I pick what posts are on the blog Only posts that go in the database are included The author has to appear in SC at least 4 of the 6 months considered I averaged the monthly posts and am only showing Authors with an average greater than 1. Here are the Top Posted Authors at Silverlight Cream for June 1, 2010 through November 30, 2010: It is my intention to post a new list sometime shortly after the 1st of every month to recognize the top posted in the previous 6 months, so next up is January 1! Some other metrics for Silverlight Cream: At the time of this posting there are 7087 articles aggregated and searchable by partial Author, partial Title, keywords (in the synopsis), or partial URL. There are also 116 tags by which the articles can be searched. At the time of this posting there are 664 articles tagged wp7dev. Stay in the 'Light!

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• Scripting out Contained Database Users

  - by Argenis

    Today’s blog post comes from a Twitter thread on which @SQLSoldier, @sqlstudent144 and @SQLTaiob were discussing the internals of contained database users. Unless you have been living under a rock, you’ve heard about the concept of contained users within a SQL Server database (hit the link if you have not). In this article I’d like to show you that you can, indeed, script out contained database users and recreate them on another database, as either contained users or as good old fashioned logins/server principals as well. Why would this be useful? Well, because you would not need to know the password for the user in order to recreate it on another instance. I know there is a limited number of scenarios where this would be necessary, but nonetheless I figured I’d throw this blog post to show how it can be done. A more obscure use case: with the password hash (which I’m about to show you how to obtain) you could also crack the password using a utility like hashcat, as highlighted on this SQLServerCentral article. The Investigation SQL Server uses System Base Tables to save the password hashes of logins and contained database users. For logins it uses sys.sysxlgns, whereas for contained database users it leverages sys.sysowners. I’ll show you what I do to figure this stuff out: I create a login/contained user, and then I immediately browse the transaction log with, for example, fn_dblog. It’s pretty obvious that only two base tables touched by the operation are sys.sysxlgns, and also sys.sysprivs – the latter is used to track permissions. If I connect to the DAC on my instance, I can query for the password hash of this login I’ve just created. A few interesting things about this hash. This was taken on my laptop, and I happen to be running SQL Server 2014 RTM CU2, which is the latest public build of SQL Server 2014 as of time of writing. In 2008 R2 and prior versions (back to 2000), the password hashes would start with 0x0100. The reason why this changed is because starting with SQL Server 2012 password hashes are kept using a SHA512 algorithm, as opposed to SHA-1 (used since 2000) or Snefru (used in 6.5 and 7.0). SHA-1 is nowadays deemed unsafe and is very easy to crack. For regular SQL logins, this information is exposed through the sys.sql_logins catalog view, so there is really no need to connect to the DAC to grab an SID/password hash pair. For contained database users, there is (currently) no method of obtaining SID or password hashes without connecting to the DAC. If we create a contained database user, this is what we get from the transaction log: Note that the System Base Table used in this case is sys.sysowners. sys.sysprivs is used as well, and again this is to track permissions. To query sys.sysowners, you would have to connect to the DAC, as I mentioned previously. And this is what you would get: There are other ways to figure out what SQL Server uses under the hood to store contained database user password hashes, like looking at the execution plan for a query to sys.dm_db_uncontained_entities (Thanks, Robert Davis!) SIDs, Logins, Contained Users, and Why You Care…Or Not. One of the reasons behind the existence of Contained Users was the concept of portability of databases: it is really painful to maintain Server Principals (Logins) synced across most shared-nothing SQL Server HA/DR technologies (Mirroring, Availability Groups, and Log Shipping). Often times you would need the Security Identifier (SID) of these logins to match across instances, and that meant that you had to fetch whatever SID was assigned to the login on the principal instance so you could recreate it on a secondary. With contained users you normally wouldn’t care about SIDs, as the users are always available (and synced, as long as synchronization takes place) across instances. Now you might be presented some particular requirement that might specify that SIDs synced between logins on certain instances and contained database users on other databases. How would you go about creating a contained database user with a specific SID? The answer is that you can’t do it directly, but there’s a little trick that would allow you to do it. Create a login with a specified SID and password hash, create a user for that server principal on a partially contained database, then migrate that user to contained using the system stored procedure sp_user_migrate_to_contained, then drop the login. CREATE LOGIN <login_name> WITH PASSWORD = <password_hash> HASHED, SID = <sid> ; GO USE <partially_contained_db>; GO CREATE USER <user_name> FROM LOGIN <login_name>; GO EXEC sp_migrate_user_to_contained @username = <user_name>, @rename = N’keep_name’, @disablelogin = N‘disable_login’; GO DROP LOGIN <login_name>; GO Here’s how this skeleton would look like in action: And now I have a contained user with a specified SID and password hash. In my example above, I renamed the user after migrated it to contained so that it is, hopefully, easier to understand. Enjoy!

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• PTLQueue : a scalable bounded-capacity MPMC queue

  - by Dave

  Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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• Extreme Optimization – Numerical Algorithm Support

  - by JoshReuben

  Function Delegates Many calculations involve the repeated evaluation of one or more user-supplied functions eg Numerical integration. The EO MathLib provides delegate types for common function signatures and the FunctionFactory class can generate new delegates from existing ones. RealFunction delegate - takes one Double parameter – can encapsulate most of the static methods of the System.Math class, as well as the classes in the Extreme.Mathematics.SpecialFunctions namespace: var sin = new RealFunction(Math.Sin); var result = sin(1); BivariateRealFunction delegate - takes two Double parameters: var atan2 = new BivariateRealFunction (Math.Atan2); var result = atan2(1, 2); TrivariateRealFunction delegate – represents a function takes three Double arguments ParameterizedRealFunction delegate - represents a function taking one Integer and one Double argument that returns a real number. The Pow method implements such a function, but the arguments need order re-arrangement: static double Power(int exponent, double x) { return ElementaryFunctions.Pow(x, exponent); } ... var power = new ParameterizedRealFunction(Power); var result = power(6, 3.2); A ComplexFunction delegate - represents a function that takes an Extreme.Mathematics.DoubleComplex argument and also returns a complex number. MultivariateRealFunction delegate - represents a function that takes an Extreme.Mathematics.LinearAlgebra.Vector argument and returns a real number. MultivariateVectorFunction delegate - represents a function that takes a Vector argument and returns a Vector. FastMultivariateVectorFunction delegate - represents a function that takes an input Vector argument and an output Matrix argument – avoiding object construction  The FunctionFactory class RealFromBivariateRealFunction and RealFromParameterizedRealFunction helper methods - transform BivariateRealFunction or a ParameterizedRealFunction into a RealFunction delegate by fixing one of the arguments, and treating this as a new function of a single argument. var tenthPower = FunctionFactory.RealFromParameterizedRealFunction(power, 10); var result = tenthPower(x); Note: There is no direct way to do this programmatically in C# - in F# you have partial value functions where you supply a subset of the arguments (as a travelling closure) that the function expects. When you omit arguments, F# generates a new function that holds onto/remembers the arguments you passed in and "waits" for the other parameters to be supplied. let sumVals x y = x + y     let sumX = sumVals 10     // Note: no 2nd param supplied.     // sumX is a new function generated from partially applied sumVals.     // ie "sumX is a partial application of sumVals." let sum = sumX 20     // Invokes sumX, passing in expected int (parameter y from original)  val sumVals : int -> int -> int val sumX : (int -> int) val sum : int = 30 RealFunctionsToVectorFunction and RealFunctionsToFastVectorFunction helper methods - combines an array of delegates returning a real number or a vector into vector or matrix functions. The resulting vector function returns a vector whose components are the function values of the delegates in the array. var funcVector = FunctionFactory.RealFunctionsToVectorFunction(     new MultivariateRealFunction(myFunc1),     new MultivariateRealFunction(myFunc2));  The IterativeAlgorithm<T> abstract base class Iterative algorithms are common in numerical computing - a method is executed repeatedly until a certain condition is reached, approximating the result of a calculation with increasing accuracy until a certain threshold is reached. If the desired accuracy is achieved, the algorithm is said to converge. This base class is derived by many classes in the Extreme.Mathematics.EquationSolvers and Extreme.Mathematics.Optimization namespaces, as well as the ManagedIterativeAlgorithm class which contains a driver method that manages the iteration process.  The ConvergenceTest abstract base class This class is used to specify algorithm Termination , convergence and results - calculates an estimate for the error, and signals termination of the algorithm when the error is below a specified tolerance. Termination Criteria - specify the success condition as the difference between some quantity and its actual value is within a certain tolerance – 2 ways: absolute error - difference between the result and the actual value. relative error is the difference between the result and the actual value relative to the size of the result. Tolerance property - specify trade-off between accuracy and execution time. The lower the tolerance, the longer it will take for the algorithm to obtain a result within that tolerance. Most algorithms in the EO NumLib have a default value of MachineConstants.SqrtEpsilon - gives slightly less than 8 digits of accuracy. ConvergenceCriterion property - specify under what condition the algorithm is assumed to converge. Using the ConvergenceCriterion enum: WithinAbsoluteTolerance / WithinRelativeTolerance / WithinAnyTolerance / NumberOfIterations Active property - selectively ignore certain convergence tests Error property - returns the estimated error after a run MaxIterations / MaxEvaluations properties - Other Termination Criteria - If the algorithm cannot achieve the desired accuracy, the algorithm still has to end – according to an absolute boundary. Status property - indicates how the algorithm terminated - the AlgorithmStatus enum values:NoResult / Busy / Converged (ended normally - The desired accuracy has been achieved) / IterationLimitExceeded / EvaluationLimitExceeded / RoundOffError / BadFunction / Divergent / ConvergedToFalseSolution. After the iteration terminates, the Status should be inspected to verify that the algorithm terminated normally. Alternatively, you can set the ThrowExceptionOnFailure to true. Result property - returns the result of the algorithm. This property contains the best available estimate, even if the desired accuracy was not obtained. IterationsNeeded / EvaluationsNeeded properties - returns the number of iterations required to obtain the result, number of function evaluations.  Concrete Types of Convergence Test classes SimpleConvergenceTest class - test if a value is close to zero or very small compared to another value. VectorConvergenceTest class - test convergence of vectors. This class has two additional properties. The Norm property specifies which norm is to be used when calculating the size of the vector - the VectorConvergenceNorm enum values: EuclidianNorm / Maximum / SumOfAbsoluteValues. The ErrorMeasure property specifies how the error is to be measured – VectorConvergenceErrorMeasure enum values: Norm / Componentwise ConvergenceTestCollection class - represent a combination of tests. The Quantifier property is a ConvergenceTestQuantifier enum that specifies how the tests in the collection are to be combined: Any / All  The AlgorithmHelper Class inherits from IterativeAlgorithm<T> and exposes two methods for convergence testing. IsValueWithinTolerance<T> method - determines whether a value is close to another value to within an algorithm's requested tolerance. IsIntervalWithinTolerance<T> method - determines whether an interval is within an algorithm's requested tolerance.

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• Best way to store a large amount of game objects and update the ones onscreen

  - by user3002473

  Good afternoon guys! I'm a young beginner game developer working on my first large scale game project and I've run into a situation where I'm not quite sure what the best solution may be (if there is a lone solution). The question may be vague (if anyone can think of a better title after having read the question, please edit it) or broad but I'm not quite sure what to do and I thought it would help just to discuss the problem with people more educated in the field. Before we get started, here are some of the questions I've looked at for help in the past: Best way to keep track of game objects Elegant way to simulate large amounts of entities within a game world What is the most efficient container to store dynamic game objects in? I've also read articles about different data structures commonly used in games to store game objects such as this one about slot maps, but none of them are really what I'm looking for. Also, if it helps at all I'm using Python 3 to design the game. It has to be Python 3, if I could I would use C++ or Unityscript or something else, but I'm restricted to having to use Python 3. My game will be a form of side scroller shooter game. In said game the player will traverse large rooms with large amounts of enemies and other game objects to update (think some of the larger areas in Cave Story or Iji). The player obviously can't see the entire room all at once, so there is a viewport that follows the player around and renders only a selection of the room and the game objects that it contains. This is not a foreign concept. The part that's getting me confused has to do with how certain game objects are updated. Some of them are to be updated constantly, regardless of whether or not they can be seen. Other objects however are only to be updated when they are onscreen (for example, an enemy would only be updated to react to the player when it is onscreen or when it is in a certain range of the screen). Another problem is that game objects have to be easily referable by other game objects; something that happens in the player's update() method may affect another object in the world. Collision detection in games is always a serious problem. I need a way of containing the game objects such that it minimizes the number of cases when testing for collisions against one another. The final problem is that of creating and destroying game objects. I think this problem is pretty self explanatory. To store the game objects then I've considered a number of different methods. The original method I had was to simply store all the objects in a hash table by an id. This method was simple, and decently fast as it allows all the objects to be looked up in O(1) complexity, and also allows them to be deleted fairly easily. Hash collisions would not be a major problem; I wasn't originally planning on using computer generated ids to store the game objects I was going to rely on them all using ids given to them by the game designer (such names would be strings like 'Player' or 'EnemyWeapon4'), and even if I did use computer generated ids, if I used a decent hashing algorithm then the chances of collisions would be around 1 in 4 billion. The problem with using a hash table however is that it is inefficient in checking to see what objects are in range of the viewport. Considering the fact that certain game objects move (as well as the viewport itself), the only solution I could think of in order to only update objects that are in the viewport would be to iterate through every object in the hash table and check if it is in the viewport or not, updating only the ones that are in the valid area. This would be incredibly slow in scenarios where the amount of game objects exceeds 500, or even 200. The second solution was to store everything in a 2-d list. The world is partitioned up into cells (a tilemap essentially), where each cell or tile is the same size and is square. Each cell would contain a list of the game objects that are currently occupying it (each game object would be inserted into a cell depending on the center of the object's collision mask). A 2-d list would allow me to take the top-left and bottom-right corners of the viewport and easily grab a rectangular area of the grid containing only the cells containing entities that are in valid range to be updated. This method also solves the problem of collision detection; when I take an entity I can find the cell that it is currently in, then check only against entities in it's cell and the 8 cells around it. One problem with this system however is that it prohibits easy lookup of game objects. One solution I had would be to simultaneously keep a hash table that would contain all the positions of the objects in the 2-d list indexed by the id of said object. The major problem with a 2-d list is that it would need to be rebuilt every single game frame (along with the hash table of object positions), which may be a serious detriment to game speed. Both systems have ups and downs and seem to solve some of each other's problems, however using them both together doesn't seem like the best solution either. If anyone has any thoughts, ideas, suggestions, comments, opinions or solutions on new data structures or better implementations of the existing data structures I have in mind, please post, any and all criticism and help is welcome. Thanks in advance! EDIT: Please don't close the question because it has a bad title, I'm just bad with names!

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• Custom graph comparison?

  - by user57828

  I'm trying to compare two graphs using hash value ( i.e, at the time of comparison, try to avoid traversing the graph ) Is there a way to make a function such that the hash values compared can also lead to determining at which height the graphs differ? The comparisons between two graphs are to be made by comparing children at a certain level. One way to compare the graphs is have a final hash value for the root node and compare them, but that wouldn't directly reflect at which level the graphs differ, since their immediate children might be the same ( or any other case ).

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• in memory datastore in haskell

  - by Simon

  I want to implement an in memory datastore for a web service in Haskell. I want to run transactions in the stm monad. When I google hash table steam Haskell I only get this: Data. BTree. HashTable. STM. The module name and complexities suggest that this is implemented as a tree. I would think that an array would be more efficient for mutable hash tables. Is there a reason to avoid using an array for an STM hashtable? Do I gain anything with this stem hash table or should I just use a steam ref to an IntMap?

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• Is there a name for this functional programming construct/pattern?

  - by dietbuddha

  I wrote a function and I'd like to find out if it is an implementation of some functional programming pattern or construct. I'd like to find out the name of this pattern or construct (if it exists)? I have a function which takes a list of functions and does this to them: wrap(fn1, fn2, fn3, fn4) # returns partial(fn4, partial(fn3, partial(fn2, fn1))) There are strong similarities to compose, reduce, and other fp metaprogramming constructs, since the functions are being arranged together and returned as one function. It also has strong similarities to decorators and Python context managers since it provides a way to encapsulate pre and post execution behaviors in one function. Which was the impetus for writing this function. I wanted the ability that context managers provide, but I wanted to be able to have it defined in one function, and to be able to layer function after function on top.

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• Why to let / not let developers test their own work

  - by pyvi

  I want to gather some arguments as to why letting a developer testing his/her own work as the last step before the product goes into production is a bad idea, because unfortunately, my place of work sometimes does this (the last time this came up, the argument boiled down to most people being too busy with other things and not having the time to get another person familiar with that part of the program - it's very specialised software). There are test plans in this case (though not always), but I am very much in favor of making a person who didn't make the changes that are tested actually doing the final testing. So I am asking if you could provide me with a good and solid list of arguments I can bring up the next time this is discussed. Or to provide counter-arguments, in case you think this is perfectly fine especially when there are formal test cases to test.

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• problem showing my website correctly in search engines

  - by dinbrca

  Hello guys, I have a website which i have indexed on google for example (like 15 days ago). some of my pages pass arguments like: http://www.bla.com/products.php?pro=bla&page=view suddently i saw that passing arguments like this isn't good for SEO purposes and started using htaccess rewrite. and changed the arguments to like this: http://www.bla.com/products/bla/*view*/ now my site on google still shows as i showed at link number 1 what should i do? i thought i should wait for the search engine to crawl my site again but nothing happened. thanks in advanced, Din

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• Writing a basic C Shell - understanding argv[] [on hold]

  - by Flame

  I have an assignment for my class to write a basic C Shell. I have found many pages that explain parts of it and some fully implemented code. I'm not going to copy, i'm just using it right now as a way to get started. So I'm at the beginning of this project obviously. One example I am looking at parses the user's input and stores a pointer to the beginning of the argument in char *argv[3]; Am I just misunderstanding this or would this technically break if there are more than 3 arguments? (say /a.out arg1 arg2 arg3 etc). Would I wanna malloc this somehow? I know a.out is considered argv[0], and the arguments argv1 - however many there are. It's probably bad practice to have too many arguments for a program, but I still would at least want to address it as I don't know what my TA's are going to use to test my shell.

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• Are HTTP requests cached? [closed]

  - by nischayn22

  Many HTTP requests are sent repeatedly by browsers on almost every page load, such as requesting the jQuery .js file etc. Since these are already used on too many sites doesn't modern browsers keep a cache for this? I am thinking of a system where the browser has a cached copy of the .js file used very very frequently. On a new request for the .js file, it sends the server a request for a hash of the .js file (provided the server can reply to that) and compares the returned hash with the cached copy's hash... rest is intuitive.

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• htaccess 301 redirect help needed

  - by John

  Due to some issues in my site many pages are visible as duplicate using : www.example.com/page.html?task=view but it's content is exactly same as www.example.com/page.html. One way is to use http 301 redirect from www.example.com/page.html?task=view to www.example.com/page.html when anybody fetches page with arguments. But links like www.example.com/page.html?task=view will remain visible to outside world. Another way is canonicalization which I don't want to use as it is difficult to insert the tag in Joomla CMS. I want to hide www.example.com/page.html?task=view from external world. Is it possible to change the url from www.example.com/page.html?task=view to www.example.com/page.html ? I mean if there is href link of www.example.com/page.html?task=view in my web page, it should be visible to external world as without any arguments. This is different from using 301 to convert externally accessed page : www.example.com/page.html?task=view to without using arguments in .htaccess.

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• Data structure for file search

  - by poly

  I've asked this question before and I got a few answers/idea, but I'm not sure how to implement them. I'm building a telecom messaging solution. Currently, I'm using a database to save my transaction/messages for the network stack I've built, and as you know it's slower than using a data structure (hash, linkedlist, etc...). My problem is that the data can be really huge, and it won't fit in the memory. I was thinking of saving the records in a file and the a key and line number in a hash, then if I want to access some record then I can get the line number from the hash, and get it from the file. I don't know how efficient is this; I think the database is doing a way better job than this on my behalf. Please share whatever you have in mind.

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• How can I track the last location of a shipment effeciently using latest date of reporting?

  - by hash

  I need to find the latest location of each cargo item in a consignment. We mostly do this by looking at the route selected for a consignment and then finding the latest (max) time entered against nodes of this route. For example if a route has 5 nodes and we have entered timings against first 3 nodes, then the latest timing (max time) will tell us its location among the 3 nodes. I am really stuck on this query regarding performance issues. Even on few hundred rows, it takes more than 2 minutes. Please suggest how can I improve this query or any alternative approach I should acquire? Note: ATA= Actual Time of Arrival and ATD = Actual Time of Departure SELECT DISTINCT(c.id) as cid,c.ref as cons_ref , c.Name, c.CustRef FROM consignments c INNER JOIN routes r ON c.Route = r.ID INNER JOIN routes_nodes rn ON rn.Route = r.ID INNER JOIN cargo_timing ct ON c.ID=ct.ConsignmentID INNER JOIN (SELECT t.ConsignmentID, Max(t.firstata) as MaxDate FROM cargo_timing t GROUP BY t.ConsignmentID ) as TMax ON TMax.MaxDate=ct.firstata AND TMax.ConsignmentID=c.ID INNER JOIN nodes an ON ct.routenodeid = an.ID INNER JOIN contract cor ON cor.ID = c.Contract WHERE c.Type = 'Road' AND ( c.ATD = 0 AND c.ATA != 0 ) AND (cor.contract_reference in ('Generic','BP001','020-543-912')) ORDER BY c.ref ASC

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• JQuery Checkbox generation

  - by Hash

  I have used the following code to generate some dynamic checkboxes. This works for the first time and adds the check box chk2 to the page and then after the trigger for the $('#newLink').click is not working. Please help me with this. <div id="chkBoxesDiv"> <input type="checkbox" id="chk1" ></input> <input id="answerText" type="text" size="30" ></input>&nbsp; <input type="button" value="add new" id="newLink"/> </div> $(document).ready(function(){ $('#newLink').click(function (event){ var i = 0; //To count the children $("#chkBoxesDiv").children().each(function(){ var child = $(this); if(child.is(":checkbox")){ i++; } }); //prevent action event.preventDefault(); //get textbox value to fill checkbox var text = $("#answerText").val(); alert(i); //if text not empty do stuff if(text != ""){ //add label $("#chk"+i).after("<label for=\"chk"+i+"\" id=\"lblchk"+i+"\">"+text+"</label>"); $("#newLink").remove(); $("#answerText").remove(); $("#lblchk1").after("<br /><input type=\"checkbox\" id=\"chk"+(1+i)+"\" ></input><input type=\"text\" id=\"answerText\" size=\"30\" ></input>&nbsp;<input type=\"button\" value=\"add new\" id=\"newLink\"/>"); } }); });

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• dot asterix operator in c++

  - by hash

  is there, and if, what it does? .*

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• dot asterisk operator in c++

  - by hash

  is there, and if, what it does? .*

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• JDK 7u25: Solutions to Issues caused by changes to Runtime.exec

  - by Devika Gollapudi

  The following examples were prepared by Java engineering for the benefit of Java developers who may have faced issues with Runtime.exec on the Windows platform. Background In JDK 7u21, the decoding of command strings specified to Runtime.exec(String), Runtime.exec(String,String[]) and Runtime.exec(String,String[],File) methods, has been made more strict. See JDK 7u21 Release Notes for more information. This caused several issues for applications. The following section describes some of the problems faced by developers and their solutions. Note: In JDK 7u25, the system property jdk.lang.Process.allowAmbigousCommands can be used to relax the checking process and helps as a workaround for some applications that cannot be changed. The workaround is only effective for applications that are run without a SecurityManager. See JDK 7u25 Release Notes for more information. Note: To understand the details of the Windows API CreateProcess call, see: http://msdn.microsoft.com/en-us/library/windows/desktop/ms682425%28v=vs.85%29.aspx There are two forms of Runtime.exec calls: with the command as string: "Runtime.exec(String command[, ...])" with the command as string array: "Runtime.exec(String[] cmdarray [, ...] )" The issues described in this section relate to the first form of call. With the first call form, developers expect the command to be passed "as is" to Windows where the command needs be split into its executable name and arguments parts first. But, in accordance with Java API, the command argument is split into executable name and arguments by spaces. Problem 1: "The file path for the command includes spaces" In the call: Runtime.getRuntime().exec("c:\\Program Files\\do.exe") the argument is split by spaces to an array of strings as: c:\\Program, Files\\do.exe The first element of parsed array is interpreted as the executable name, verified by SecurityManager (if present) and surrounded by quotations to avoid ambiguity in executable path. This results in the wrong command: "c:\\Program" "Files\\do.exe" which will fail. Solution: Use the ProcessBuilder class, or the Runtime.exec(String[] cmdarray [, ...] ) call, or quote the executable path. Where it is not possible to change the application code and where a SecurityManager is not used, the Java property jdk.lang.Process.allowAmbigousCommands could be used by setting its value to "true" from the command line: -Djdk.lang.Process.allowAmbigousCommands=true This will relax the checking process to allow ambiguous input. Examples: new ProcessBuilder("c:\\Program Files\\do.exe").start() Runtime.getRuntime().exec(new String[]{"c:\\Program Files\\do.exe"}) Runtime.getRuntime().exec("\"c:\\Program Files\\do.exe\"") Problem 2: "Shell command/.bat/.cmd IO redirection" The following implicit cmd.exe calls: Runtime.getRuntime().exec("dir temp.txt") new ProcessBuilder("foo.bat", "", "temp.txt").start() Runtime.getRuntime().exec(new String[]{"foo.cmd", "", "temp.txt"}) lead to the wrong command: "XXXX" "" temp.txt Solution: To specify the command correctly, use the following options: Runtime.getRuntime().exec("cmd /C \"dir temp.txt\"") new ProcessBuilder("cmd", "/C", "foo.bat temp.txt").start() Runtime.getRuntime().exec(new String[]{"cmd", "/C", "foo.cmd temp.txt"}) or Process p = new ProcessBuilder("cmd", "/C" "XXX").redirectOutput(new File("temp.txt")).start(); Problem 3: "Group execution of shell command and/or .bat/.cmd files" Due to enforced verification procedure, arguments in the following calls create the wrong commands.: Runtime.getRuntime().exec("first.bat && second.bat") new ProcessBuilder("dir", "&&", "second.bat").start() Runtime.getRuntime().exec(new String[]{"dir", "|", "more"}) Solution: To specify the command correctly, use the following options: Runtime.exec("cmd /C \"first.bat && second.bat\"") new ProcessBuilder("cmd", "/C", "dir && second.bat").start() Runtime.exec(new String[]{"cmd", "/C", "dir | more"}) The same scenario also works for the "&", "||", "^" operators of the cmd.exe shell. Problem 4: ".bat/.cmd with special DOS chars in quoted params” Due to enforced verification, arguments in the following calls will cause exceptions to be thrown.: Runtime.getRuntime().exec("log.bat \"error new ProcessBuilder("log.bat", "error Runtime.getRuntime().exec(new String[]{"log.bat", "error Solution: To specify the command correctly, use the following options: Runtime.getRuntime().exec("cmd /C log.bat \"error new ProcessBuilder("cmd", "/C", "log.bat", "error Runtime.getRuntime().exec(new String[]{"cmd", "/C", "log.bat", "error Examples: Complicated redirection for shell construction: cmd /c dir /b C:\ "my lovely spaces.txt" becomes Runtime.getRuntime().exec(new String[]{"cmd", "/C", "dir \b \"my lovely spaces.txt\"" }); The Golden Rule: In most cases, cmd.exe has two arguments: "/C" and the command for interpretation.

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