Search Results

Search found 24018 results on 961 pages for 'platform specific'.

Page 607/961 | < Previous Page | 603 604 605 606 607 608 609 610 611 612 613 614  | Next Page >

• Database - Designing an "Events" Table

  - by Alix Axel

  After reading the tips from this great Nettuts+ article I've come up with a table schema that would separate highly volatile data from other tables subjected to heavy reads and at the same time lower the number of tables needed in the whole database schema, however I'm not sure if this is a good idea since it doesn't follow the rules of normalization and I would like to hear your advice, here is the general idea: I've four types of users modeled in a Class Table Inheritance structure, in the main "user" table I store data common to all the users (id, username, password, several flags, ...) along with some TIMESTAMP fields (date_created, date_updated, date_activated, date_lastLogin, ...). To quote the tip #16 from the Nettuts+ article mentioned above: Example 2: You have a “last_login” field in your table. It updates every time a user logs in to the website. But every update on a table causes the query cache for that table to be flushed. You can put that field into another table to keep updates to your users table to a minimum. Now it gets even trickier, I need to keep track of some user statistics like how many unique times a user profile was seen how many unique times a ad from a specific type of user was clicked how many unique times a post from a specific type of user was seen and so on... In my fully normalized database this adds up to about 8 to 10 additional tables, it's not a lot but I would like to keep things simple if I could, so I've come up with the following "events" table: |------|----------------|----------------|--------------|-----------| | ID | TABLE | EVENT | DATE | IP | |------|----------------|----------------|--------------|-----------| | 1 | user | login | 201004190030 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 1 | user | login | 201004190230 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | created | 201004190031 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | activated | 201004190234 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | approved | 201004190930 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | login | 201004191200 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | created | 201004191230 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | impressed | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | blocked | 201004200319 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | deleted | 201004200320 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| Basically the ID refers to the primary key (id) field in the TABLE table, I believe the rest should be pretty straightforward. One thing that I've come to like in this design is that I can keep track of all the user logins instead of just the last one, and thus generate some interesting metrics with that data. Due to the nature of the events table I also thought of making some optimizations, such as: #9: Since there is only a finite number of tables and a finite (and predetermined) number of events, the TABLE and EVENTS columns could be setup as ENUMs instead of VARCHARs to save some space. #14: Store IPs as UNSIGNED INT with INET_ATON() instead of VARCHARs. Store DATEs as TIMESTAMPs instead of DATETIMEs. Use the ARCHIVE (or the CSV?) engine instead of InnoDB / MyISAM. Overall, each event would only consume 14 bytes which is okay for my traffic I guess. Pros: Ability to store more detailed data (such as logins). No need to design (and code for) almost a dozen additional tables (dates and statistics). Reduces a few columns per table and keeps volatile data separated. Cons: Non-relational (still not as bad as EAV): SELECT * FROM events WHERE id = 2 AND table = 'user' ORDER BY date DESC(); 6 bytes overhead per event (ID, TABLE and EVENT). I'm more inclined to go with this approach since the pros seem to far outweigh the cons, but I'm still a little bit reluctant.. Am I missing something? What are your thoughts on this? Thanks!

  Read the article

• How can I read the verbose output from a Cmdlet in C# using Exchange Powershell

  - by mrkeith

  Environment: Exchange 2007 sp3 (2003 sp2 mixed mode) Visual Studio 2008, .Net 3.5 Hello, I'm working with an Exchange powershell move-mailbox cmdlet and have noted when I do so from the Exchange Management shell (using the Verbose switch) there is a ton of real-time information provided. To provide a little context, I'm attempting to create a UI application that moves mailboxes similarly to the Exchange Management Console but desire to support an input file and specific server/database destinations for each entry (and threading). Here's roughly what I have at present but I'm not sure if there is an event I need to register for or what... And to be clear, I desire to get this information in real-time so I may update my UI to reflect what's occurring in the move sequence for the appropriate user (pretty much like the native functionality offered in the Management Console). And in case you are wondering, the reason why I'm not content with the Management Console functionality is, I have an algorithm which I'm using to balance users depending on storage limit, Blackberry use, journaling, exception mailbox size etc which demands user be mapped to specific locations... and I do not desire to create many/several move groups for each common destination or to hunt for lists of users individually through the management console UI. I can not seem to find any good documentation or examples of how to tie into reading the verbose messages that are provided within the console using C# (I see value in being able to read this kind of information in many different scenarios). I've explored the Invoke and InvokeAsync methods and the StateChanged & DataReady events but none of these seem to provide the information (verbose comments) that I'm after. Any direction or examples that can be provided will be very appreciated! A code sample which is little more than how I would ordinarily call any other powershell command follows: // config to use ExMgmt shell, create runspace and open it RunspaceConfiguration rsConfig = RunspaceConfiguration.Create(); PSSnapInException snapInException = null; PSSnapInInfo info = rsConfig.AddPSSnapIn("Microsoft.Exchange.Management.PowerShell.Admin", out snapInException); if (snapInException != null) throw snapInException; Runspace runspace = RunspaceFactory.CreateRunspace(rsConfig); try { runspace.Open(); // create a pipeline and feed script text Pipeline pipeline = runspace.CreatePipeline(); string targetDatabase = @"myServer\myStorageGroup\myDB"; string mbxOwner = "[email protected]"; Command myMoveMailbox = new Command("Move-Mailbox", false, false); myMoveMailbox.Parameters.Add("Identity", mbxOwner); myMoveMailbox.Parameters.Add("TargetDatabase", targetDatabase); myMoveMailbox.Parameters.Add("Verbose"); myMoveMailbox.Parameters.Add("ValidateOnly"); myMoveMailbox.Parameters.Add("Confirm", false); pipeline.Commands.Add(myMoveMailbox); System.Collections.ObjectModel.Collection output = null; // these next few lines that are commented out are where I've tried // registering for events and calling asynchronously but this doesn't // seem to get me anywhere closer // //pipeline.StateChanged += new EventHandler(pipeline_StateChanged); //pipeline.Output.DataReady += new EventHandler(Output_DataReady); //pipeline.InvokeAsync(); //pipeline.Input.Close(); //return; tried these variations that are commented out but none seem to be useful output = pipeline.Invoke(); // Check for errors in the pipeline and throw an exception if necessary if (pipeline.Error != null && pipeline.Error.Count 0) { StringBuilder pipelineError = new StringBuilder(); pipelineError.AppendFormat("Error calling Test() Cmdlet. "); foreach (object item in pipeline.Error.ReadToEnd()) pipelineError.AppendFormat("{0}\n", item.ToString()); throw new Exception(pipelineError.ToString()); } foreach (PSObject psObject in output) { // blah, blah, blah // this is normally where I would read details about a particular PS command // but really pertains to a command once it finishes and has nothing to do with // the verbose messages that I'm after... since this part of the methods pertains // to the after-effects of a command having run, I'm suspecting I need to look to // the asynch invoke method but am not certain or knowing how. } } finally { runspace.Close(); } Thanks! Keith

  Read the article

• Adding functionality to any TextReader

  - by strager

  I have a Location class which represents a location somewhere in a stream. (The class isn't coupled to any specific stream.) The location information will be used to match tokens to location in the input in my parser, to allow for nicer error reporting to the user. I want to add location tracking to a TextReader instance. This way, while reading tokens, I can grab the location (which is updated by the TextReader as data is read) and give it to the token during the tokenization process. I am looking for a good approach on accomplishing this goal. I have come up with several designs. Manual location tracking Every time I need to read from the TextReader, I call AdvanceString on the Location object of the tokenizer with the data read. Advantages Very simple. No class bloat. No need to rewrite the TextReader methods. Disadvantages Couples location tracking logic to tokenization process. Easy to forget to track something (though unit testing helps with this). Bloats existing code. Plain TextReader wrapper Create a LocatedTextReaderWrapper class which surrounds each method call, tracking a Location property. Example: public class LocatedTextReaderWrapper : TextReader { private TextReader source; public Location Location { get; set; } public LocatedTextReaderWrapper(TextReader source) : this(source, new Location()) { } public LocatedTextReaderWrapper(TextReader source, Location location) { this.Location = location; this.source = source; } public override int Read(char[] buffer, int index, int count) { int ret = this.source.Read(buffer, index, count); if(ret >= 0) { this.location.AdvanceString(string.Concat(buffer.Skip(index).Take(count))); } return ret; } // etc. } Advantages Tokenization doesn't know about Location tracking. Disadvantages User needs to create and dispose a LocatedTextReaderWrapper instance, in addition to their TextReader instance. Doesn't allow different types of tracking or different location trackers to be added without layers of wrappers. Event-based TextReader wrapper Like LocatedTextReaderWrapper, but decouples it from the Location object raising an event whenever data is read. Advantages Can be reused for other types of tracking. Tokenization doesn't know about Location tracking or other tracking. Can have multiple, independent Location objects (or other methods of tracking) tracking at once. Disadvantages Requires boilerplate code to enable location tracking. User needs to create and dispose the wrapper instance, in addition to their TextReader instance. Aspect-orientated approach Use AOP to perform like the event-based wrapper approach. Advantages Can be reused for other types of tracking. Tokenization doesn't know about Location tracking or other tracking. No need to rewrite the TextReader methods. Disadvantages Requires external dependencies, which I want to avoid. I am looking for the best approach in my situation. I would like to: Not bloat the tokenizer methods with location tracking. Not require heavy initialization in user code. Not have any/much boilerplate/duplicated code. (Perhaps) not couple the TextReader with the Location class. Any insight into this problem and possible solutions or adjustments are welcome. Thanks! (For those who want a specific question: What is the best way to wrap the functionality of a TextReader?) I have implemented the "Plain TextReader wrapper" and "Event-based TextReader wrapper" approaches and am displeased with both, for reasons mentioned in their disadvantages.

  Read the article

• Backbone.js Model change events in nested collections not firing as expected

  - by Pallavi Kaushik

  I'm trying to use backbone.js in my first "real" application and I need some help debugging why certain model change events are not firing as I would expect. I have a web service at /employees/{username}/tasks which returns a JSON array of task objects, with each task object nesting a JSON array of subtask objects. For example, [{ "id":45002, "name":"Open Dining Room", "subtasks":[ {"id":1,"status":"YELLOW","name":"Clean all tables"}, {"id":2,"status":"RED","name":"Clean main floor"}, {"id":3,"status":"RED","name":"Stock condiments"}, {"id":4,"status":"YELLOW","name":"Check / replenish trays"} ] },{ "id":47003, "name":"Open Registers", "subtasks":[ {"id":1,"status":"YELLOW","name":"Turn on all terminals"}, {"id":2,"status":"YELLOW","name":"Balance out cash trays"}, {"id":3,"status":"YELLOW","name":"Check in promo codes"}, {"id":4,"status":"YELLOW","name":"Check register promo placards"} ] }] Another web service allows me to change the status of a specific subtask in a specific task, and looks like this: /tasks/45002/subtasks/1/status/red [aside - I intend to change this to a HTTP Post-based service, but the current implementation is easier for debugging] I have the following classes in my JS app: Subtask Model and Subtask Collection var Subtask = Backbone.Model.extend({}); var SubtaskCollection = Backbone.Collection.extend({ model: Subtask }); Task Model with a nested instance of a Subtask Collection var Task = Backbone.Model.extend({ initialize: function() { // each Task has a reference to a collection of Subtasks this.subtasks = new SubtaskCollection(this.get("subtasks")); // status of each Task is based on the status of its Subtasks this.update_status(); }, ... }); var TaskCollection = Backbone.Collection.extend({ model: Task }); Task View to renders the item and listen for change events to the model var TaskView = Backbone.View.extend({ tagName: "li", template: $("#TaskTemplate").template(), initialize: function() { _.bindAll(this, "on_change", "render"); this.model.bind("change", this.on_change); }, ... on_change: function(e) { alert("task model changed!"); } }); When the app launches, I instantiate a TaskCollection (using the data from the first web service listed above), bind a listener for change events to the TaskCollection, and set up a recurring setTimeout to fetch() the TaskCollection instance. ... TASKS = new TaskCollection(); TASKS.url = ".../employees/" + username + "/tasks" TASKS.fetch({ success: function() { APP.renderViews(); } }); TASKS.bind("change", function() { alert("collection changed!"); APP.renderViews(); }); // Poll every 5 seconds to keep the models up-to-date. setInterval(function() { TASKS.fetch(); }, 5000); ... Everything renders as expected the first time. But at this point, I would expect either (or both) a Collection change event or a Model change event to get fired if I change a subtask's status using my second web service, but this does not happen. Funnily, I did get change events to fire if I added one additional level of nesting, with the web service returning a single object that has the Tasks Collection embedded, for example: "employee":"pkaushik", "tasks":[{"id":45002,"subtasks":[{"id":1..... But this seems klugey... and I'm afraid I haven't architected my app right. I'll include more code if it helps, but this question is already rather verbose. Thoughts?

  Read the article

• Why do we need different CPU architecture for server & mini/mainframe & mixed-core?

  - by claws

  Hello, I was just wondering what other CPU architectures are available other than INTEL & AMD. So, found List of CPU architectures on Wikipedia. It categorizes notable CPU architectures into following categories. Embedded CPU architectures Microcomputer CPU architectures Workstation/Server CPU architectures Mini/Mainframe CPU architectures Mixed core CPU architectures I was analyzing the purposes and have few doubts. I taking Microcomputer CPU (PC) architecture as reference and comparing others. Embedded CPU architecture: They are a completely new world. Embedded systems are small & do very specific task mostly real time & low power consuming so we do not need so many & such wide registers available in a microcomputer CPU (typical PC). In other words we do need a new small & tiny architecture. Hence new architecture & new instruction RISC. The above point also clarifies why do we need a separate operating system (RTOS). Workstation/Server CPU architectures I don't know what is a workstation. Someone clarify regarding the workstation. As of the server. It is dedicated to run a specific software (server software like httpd, mysql etc.). Even if other processes run we need to give server process priority therefore there is a need for new scheduling scheme and thus we need operating system different than general purpose one. If you have any more points for the need of server OS please mention. But I don't get why do we need a new CPU Architecture. Why cant Microcomputer CPU architecture do the job. Can someone please clarify? Mini/Mainframe CPU architectures Again I don't know what are these & what miniframes or mainframes used for? I just know they are very big and occupy complete floor. But I never read about some real world problems they are trying to solve. If any one working on one of these. Share your knowledge. Can some one clarify its purpose & why is it that microcomputer CPU archicture not suitable for it? Is there a new kind of operating system for this too? Why? Mixed core CPU architectures Never heard of these. If possible please keep your answer in this format: XYZ CPU architectures Purpose of XYZ Need for a new architecture. why can't current microcomputer CPU architecture work? They go upto 3GHZ & have upto 8 cores. Need for a new Operating System Why do we need a new kind of operating system for this kind of archictures?

  Read the article

• nhibernate sql Express connection issue - error: 26 - Error Locating Server/Instance Specified

  - by frosty

  I can connect fine with normal ado.net. However i get the following error when i tried to connect nHibernate. hibernate.cfg.xml <?xml version="1.0" encoding="utf-8" ?> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</property> <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property> <property name="connection.connection_string">Server=xxxxx\SQLEXPRESS; Database=xxxxx; User ID=xxxxx; Password=xxxxx; Trusted_Connection=True</property> <property name="proxyfactory.factory_class">NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle</property> <property name="show_sql">true</property> </session-factory> </hibernate-configuration> Server error A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) Full stack [SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)] System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +4845255 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +194 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject) +4858557 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +90 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +342 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +221 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +189 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +185 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +31 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +433 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +499 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 NHibernate.Connection.DriverConnectionProvider.GetConnection() +102 NHibernate.Tool.hbm2ddl.SuppliedConnectionProviderConnectionHelper.Prepare() +15 NHibernate.Tool.hbm2ddl.SchemaMetadataUpdater.GetReservedWords(Dialect dialect, IConnectionHelper connectionHelper) +65 NHibernate.Tool.hbm2ddl.SchemaMetadataUpdater.Update(ISessionFactory sessionFactory) +80 NHibernate.Impl.SessionFactoryImpl..ctor(Configuration cfg, IMapping mapping, Settings settings, EventListeners listeners) +599 NHibernate.Cfg.Configuration.BuildSessionFactory() +87 XXX.Domain.Repositories.NHibernateHelper.get_SessionFactory() in D:\dev\MyProject\XXX\XXX.Domain\Repositories\NHibernateHelper.cs:23 XXX.Domain.Repositories.NHibernateHelper.OpenSession() in D:\dev\MyProject\XXX\XXX.Domain\Repositories\NHibernateHelper.cs:31 XXX.Domain.Repositories.EntryRepository.GetCountByGmapId(Int32 gmapId) in D:\dev\MyProject\XXX\XXX.Domain\Repositories\EntryRepository.cs:152 XXX.Controls.Activity.BindRepeater(Int32 id) in D:\dev\MyProject\XXX\XXX.Controls\Activity.ascx.cs:58 XXX.Controls.Activity.DropDownListMaps_SelectedIndexChanged(Object sender, EventArgs e) in D:\dev\MyProject\XXX\XXX.Controls\Activity.ascx.cs:75 System.Web.UI.WebControls.ListControl.OnSelectedIndexChanged(EventArgs e) +111 System.Web.UI.WebControls.DropDownList.RaisePostDataChangedEvent() +134 System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent() +10 System.Web.UI.Page.RaiseChangedEvents() +165 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1485

  Read the article

• Partial generic type inference possible in C#?

  - by Lasse V. Karlsen

  I am working on rewriting my fluent interface for my IoC class library, and when I refactored some code in order to share some common functionality through a base class, I hit upon a snag. Note: This is something I want to do, not something I have to do. If I have to make do with a different syntax, I will, but if anyone has an idea on how to make my code compile the way I want it, it would be most welcome. I want some extension methods to be available for a specific base-class, and these methods should be generic, with one generic type, related to an argument to the method, but the methods should also return a specific type related to the particular descendant they're invoked upon. Better with a code example than the above description methinks. Here's a simple and complete example of what doesn't work: using System; namespace ConsoleApplication16 { public class ParameterizedRegistrationBase { } public class ConcreteTypeRegistration : ParameterizedRegistrationBase { public void SomethingConcrete() { } } public class DelegateRegistration : ParameterizedRegistrationBase { public void SomethingDelegated() { } } public static class Extensions { public static ParameterizedRegistrationBase Parameter<T>( this ParameterizedRegistrationBase p, string name, T value) { return p; } } class Program { static void Main(string[] args) { ConcreteTypeRegistration ct = new ConcreteTypeRegistration(); ct .Parameter<int>("age", 20) .SomethingConcrete(); // <-- this is not available DelegateRegistration del = new DelegateRegistration(); del .Parameter<int>("age", 20) .SomethingDelegated(); // <-- neither is this } } } If you compile this, you'll get: 'ConsoleApplication16.ParameterizedRegistrationBase' does not contain a definition for 'SomethingConcrete' and no extension method 'SomethingConcrete'... 'ConsoleApplication16.ParameterizedRegistrationBase' does not contain a definition for 'SomethingDelegated' and no extension method 'SomethingDelegated'... What I want is for the extension method (Parameter<T>) to be able to be invoked on both ConcreteTypeRegistration and DelegateRegistration, and in both cases the return type should match the type the extension was invoked on. The problem is as follows: I would like to write: ct.Parameter<string>("name", "Lasse") ^------^ notice only one generic argument but also that Parameter<T> returns an object of the same type it was invoked on, which means: ct.Parameter<string>("name", "Lasse").SomethingConcrete(); ^ ^-------+-------^ | | +---------------------------------------------+ .SomethingConcrete comes from the object in "ct" which in this case is of type ConcreteTypeRegistration Is there any way I can trick the compiler into making this leap for me? If I add two generic type arguments to the Parameter method, type inference forces me to either provide both, or none, which means this: public static TReg Parameter<TReg, T>( this TReg p, string name, T value) where TReg : ParameterizedRegistrationBase gives me this: Using the generic method 'ConsoleApplication16.Extensions.Parameter<TReg,T>(TReg, string, T)' requires 2 type arguments Using the generic method 'ConsoleApplication16.Extensions.Parameter<TReg,T>(TReg, string, T)' requires 2 type arguments Which is just as bad. I can easily restructure the classes, or even make the methods non-extension-methods by introducing them into the hierarchy, but my question is if I can avoid having to duplicate the methods for the two descendants, and in some way declare them only once, for the base class. Let me rephrase that. Is there a way to change the classes in the first code example above, so that the syntax in the Main-method can be kept, without duplicating the methods in question? The code will have to be compatible with both C# 3.0 and 4.0. Edit: The reason I'd rather not leave both generic type arguments to inference is that for some services, I want to specify a parameter value for a constructor parameter that is of one type, but pass in a value that is a descendant. For the moment, matching of specified argument values and the correct constructor to call is done using both the name and the type of the argument. Let me give an example: ServiceContainerBuilder.Register<ISomeService>(r => r .From(f => f.ConcreteType<FileService>(ct => ct .Parameter<Stream>("source", new FileStream(...))))); ^--+---^ ^---+----^ | | | +- has to be a descendant of Stream | +- has to match constructor of FileService If I leave both to type inference, the parameter type will be FileStream, not Stream.

  Read the article

• round off and displaying the values

  - by S.PRATHIBA

  Hi all, I have the following code: import java.io.; import java.sql.; import java.math.; import java.lang.; public class Testd1{ public static void main(String[] args) { System.out.println("Sum of the specific column!"); Connection con = null; int m=1; double sum,sum1,sum2; int e[]; e=new int[100]; int p; int decimalPlaces = 5; for( int i=0;i< e.length;i++) { e[i]=0; } double b2,c2,d2,u2,v2; int i,j,k,x,y; double mat[][]=new double[10][10]; try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection ("jdbc:mysql://localhost:3306/prathi","root","mysql"); try{ Statement st = con.createStatement(); ResultSet res = st.executeQuery("SELECT Service_ID,SUM(consumer_feedback) FROM consumer1 group by Service_ID"); while (res.next()){ int data=res.getInt(1); System.out.println(data); System.out.println("\n\n"); int c1 = res.getInt(2); e[m]=res.getInt(2); if(e[m]<0) e[m]=0; m++; System.out.print(c1); System.out.println("\t\t"); } sum=e[1]+e[2]+e[3]+e[4]+e[5]; System.out.println("\n \n The sum is" +sum); for( p=21; p<=25; p++) { if(e[p] != 0) e[p]=e[p]/(int)sum; //I have type casted sum to get output BigDecimal bd1 = new BigDecimal(e[p]); bd1 = bd1.setScale(decimalPlaces, BigDecimal.ROUND_HALF_UP); // setScale is immutable e[p] = bd1.intValue(); System.out.println("\n\n The normalized value is" +e[p]); mat[4][p-21]=e[p]; } } catch (SQLException s){ System.out.println("SQL statement is not executed!"); } } catch (Exception e1){ e1.printStackTrace(); } } } I have a table named consumer1.After calculating the sum i am getting the values as follows mysql select Service_ID,sum(consumer_feedback) from consumer1 group by Service_ ID; Service_ID sum(consumer_feedback) 31 17 32 0 33 60 34 38 35 | 38 In my program I am getting the sum for each Service_ID correctly.But,after normalization ie while I am calculating 17/153=0.111 I am getting the normalized value is 0.I want the normalized values to be displayed correctly after rounding off.My output is as follows C:javac Testd1.java C:java Testd1 Sum of the specific column! 31 17 32 0 33 60 34 38 35 38 The sum is153.0 The normalized value is0 The normalized value is0 The normalized value is0 The normalized value is0 The normalized value is0 But,after normalization i want to get 17/153=0.111 I am getting the normalized value is 0.I want these values to be rounded off.

  Read the article

• Code golf: Word frequency chart

  - by ChristopheD

  The challenge: Build an ASCII chart of the most commonly used words in a given text. The rules: Only accept a-z and A-Z (alphabetic characters) as part of a word. Ignore casing (She == she for our purpose). Ignore the following words (quite arbitary, I know): the, and, of, to, a, i, it, in, or, is Clarification: considering don't: this would be taken as 2 different 'words' in the ranges a-z and A-Z: (don and t). Optionally (it's too late to be formally changing the specifications now) you may choose to drop all single-letter 'words' (this could potentially make for a shortening of the ignore list too). Parse a given text (read a file specified via command line arguments or piped in; presume us-ascii) and build us a word frequency chart with the following characteristics: Display the chart (also see the example below) for the 22 most common words (ordered by descending frequency). The bar width represents the number of occurences (frequency) of the word (proportionally). Append one space and print the word. Make sure these bars (plus space-word-space) always fit: bar + [space] + word + [space] should be always <= 80 characters (make sure you account for possible differing bar and word lenghts: e.g.: the second most common word could be a lot longer then the first while not differing so much in frequency). Maximize bar width within these constraints and scale the bars appropriately (according to the frequencies they represent). An example: The text for the example can be found here (Alice's Adventures in Wonderland, by Lewis Carroll). This specific text would yield the following chart: _________________________________________________________________________ |_________________________________________________________________________| she |_______________________________________________________________| you |____________________________________________________________| said |____________________________________________________| alice |______________________________________________| was |__________________________________________| that |___________________________________| as |_______________________________| her |____________________________| with |____________________________| at |___________________________| s |___________________________| t |_________________________| on |_________________________| all |______________________| this |______________________| for |______________________| had |_____________________| but |____________________| be |____________________| not |___________________| they |__________________| so For your information: these are the frequencies the above chart is built upon: [('she', 553), ('you', 481), ('said', 462), ('alice', 403), ('was', 358), ('that ', 330), ('as', 274), ('her', 248), ('with', 227), ('at', 227), ('s', 219), ('t' , 218), ('on', 204), ('all', 200), ('this', 181), ('for', 179), ('had', 178), (' but', 175), ('be', 167), ('not', 166), ('they', 155), ('so', 152)] A second example (to check if you implemented the complete spec): Replace every occurence of you in the linked Alice in Wonderland file with superlongstringstring: ________________________________________________________________ |________________________________________________________________| she |_______________________________________________________| superlongstringstring |_____________________________________________________| said |______________________________________________| alice |________________________________________| was |_____________________________________| that |______________________________| as |___________________________| her |_________________________| with |_________________________| at |________________________| s |________________________| t |______________________| on |_____________________| all |___________________| this |___________________| for |___________________| had |__________________| but |_________________| be |_________________| not |________________| they |________________| so The winner: Shortest solution (by character count, per language). Have fun! Edit: Table summarizing the results so far (2012-02-15) (originally added by user Nas Banov): Language Relaxed Strict ========= ======= ====== GolfScript 130 143 Perl 185 Windows PowerShell 148 199 Mathematica 199 Ruby 185 205 Unix Toolchain 194 228 Python 183 243 Clojure 282 Scala 311 Haskell 333 Awk 336 R 298 Javascript 304 354 Groovy 321 Matlab 404 C# 422 Smalltalk 386 PHP 450 F# 452 TSQL 483 507 The numbers represent the length of the shortest solution in a specific language. "Strict" refers to a solution that implements the spec completely (draws |____| bars, closes the first bar on top with a ____ line, accounts for the possibility of long words with high frequency etc). "Relaxed" means some liberties were taken to shorten to solution. Only solutions shorter then 500 characters are included. The list of languages is sorted by the length of the 'strict' solution. 'Unix Toolchain' is used to signify various solutions that use traditional *nix shell plus a mix of tools (like grep, tr, sort, uniq, head, perl, awk).

  Read the article

• Performing Aggregate Functions on Multi-Million Row Tables

  - by Daniel Short

  I'm having some serious performance issues with a multi-million row table that I feel I should be able to get results from fairly quick. Here's a run down of what I have, how I'm querying it, and how long it's taking: I'm running SQL Server 2008 Standard, so Partitioning isn't currently an option I'm attempting to aggregate all views for all inventory for a specific account over the last 30 days. All views are stored in the following table: CREATE TABLE [dbo].[LogInvSearches_Daily]( [ID] [bigint] IDENTITY(1,1) NOT NULL, [Inv_ID] [int] NOT NULL, [Site_ID] [int] NOT NULL, [LogCount] [int] NOT NULL, [LogDay] [smalldatetime] NOT NULL, CONSTRAINT [PK_LogInvSearches_Daily] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY] ) ON [PRIMARY] This table has 132,000,000 records, and is over 4 gigs. A sample of 10 rows from the table: ID Inv_ID Site_ID LogCount LogDay -------------------- ----------- ----------- ----------- ----------------------- 1 486752 48 14 2009-07-21 00:00:00 2 119314 51 16 2009-07-21 00:00:00 3 313678 48 25 2009-07-21 00:00:00 4 298863 0 1 2009-07-21 00:00:00 5 119996 0 2 2009-07-21 00:00:00 6 463777 534 7 2009-07-21 00:00:00 7 339976 503 2 2009-07-21 00:00:00 8 333501 570 4 2009-07-21 00:00:00 9 453955 0 12 2009-07-21 00:00:00 10 443291 0 4 2009-07-21 00:00:00 (10 row(s) affected) I have the following index on LogInvSearches_Daily: /****** Object: Index [IX_LogInvSearches_Daily_LogDay] Script Date: 05/12/2010 11:08:22 ******/ CREATE NONCLUSTERED INDEX [IX_LogInvSearches_Daily_LogDay] ON [dbo].[LogInvSearches_Daily] ( [LogDay] ASC ) INCLUDE ( [Inv_ID], [LogCount]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] I need to pull inventory only from the Inventory for a specific account id. I have an index on the Inventory as well. I'm using the following query to aggregate the data and give me the top 5 records. This query is currently taking 24 seconds to return the 5 rows: StmtText ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- SELECT TOP 5 Sum(LogCount) AS Views , DENSE_RANK() OVER(ORDER BY Sum(LogCount) DESC, Inv_ID DESC) AS Rank , Inv_ID FROM LogInvSearches_Daily D (NOLOCK) WHERE LogDay DateAdd(d, -30, getdate()) AND EXISTS( SELECT NULL FROM propertyControlCenter.dbo.Inventory (NOLOCK) WHERE Acct_ID = 18731 AND Inv_ID = D.Inv_ID ) GROUP BY Inv_ID (1 row(s) affected) StmtText ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |--Top(TOP EXPRESSION:((5))) |--Sequence Project(DEFINE:([Expr1007]=dense_rank)) |--Segment |--Segment |--Sort(ORDER BY:([Expr1006] DESC, [D].[Inv_ID] DESC)) |--Stream Aggregate(GROUP BY:([D].[Inv_ID]) DEFINE:([Expr1006]=SUM([LOALogs].[dbo].[LogInvSearches_Daily].[LogCount] as [D].[LogCount]))) |--Sort(ORDER BY:([D].[Inv_ID] ASC)) |--Nested Loops(Inner Join, OUTER REFERENCES:([D].[Inv_ID])) |--Nested Loops(Inner Join, OUTER REFERENCES:([Expr1011], [Expr1012], [Expr1010])) | |--Compute Scalar(DEFINE:(([Expr1011],[Expr1012],[Expr1010])=GetRangeWithMismatchedTypes(dateadd(day,(-30),getdate()),NULL,(6)))) | | |--Constant Scan | |--Index Seek(OBJECT:([LOALogs].[dbo].[LogInvSearches_Daily].[IX_LogInvSearches_Daily_LogDay] AS [D]), SEEK:([D].[LogDay] > [Expr1011] AND [D].[LogDay] < [Expr1012]) ORDERED FORWARD) |--Index Seek(OBJECT:([propertyControlCenter].[dbo].[Inventory].[IX_Inventory_Acct_ID]), SEEK:([propertyControlCenter].[dbo].[Inventory].[Acct_ID]=(18731) AND [propertyControlCenter].[dbo].[Inventory].[Inv_ID]=[LOA (13 row(s) affected) I tried using a CTE to pick up the rows first and aggregate them, but that didn't run any faster, and gives me essentially the same execution plan. (1 row(s) affected) StmtText ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --SET SHOWPLAN_TEXT ON; WITH getSearches AS ( SELECT LogCount -- , DENSE_RANK() OVER(ORDER BY Sum(LogCount) DESC, Inv_ID DESC) AS Rank , D.Inv_ID FROM LogInvSearches_Daily D (NOLOCK) INNER JOIN propertyControlCenter.dbo.Inventory I (NOLOCK) ON Acct_ID = 18731 AND I.Inv_ID = D.Inv_ID WHERE LogDay DateAdd(d, -30, getdate()) -- GROUP BY Inv_ID ) SELECT Sum(LogCount) AS Views, Inv_ID FROM getSearches GROUP BY Inv_ID (1 row(s) affected) StmtText ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |--Stream Aggregate(GROUP BY:([D].[Inv_ID]) DEFINE:([Expr1004]=SUM([LOALogs].[dbo].[LogInvSearches_Daily].[LogCount] as [D].[LogCount]))) |--Sort(ORDER BY:([D].[Inv_ID] ASC)) |--Nested Loops(Inner Join, OUTER REFERENCES:([D].[Inv_ID])) |--Nested Loops(Inner Join, OUTER REFERENCES:([Expr1008], [Expr1009], [Expr1007])) | |--Compute Scalar(DEFINE:(([Expr1008],[Expr1009],[Expr1007])=GetRangeWithMismatchedTypes(dateadd(day,(-30),getdate()),NULL,(6)))) | | |--Constant Scan | |--Index Seek(OBJECT:([LOALogs].[dbo].[LogInvSearches_Daily].[IX_LogInvSearches_Daily_LogDay] AS [D]), SEEK:([D].[LogDay] > [Expr1008] AND [D].[LogDay] < [Expr1009]) ORDERED FORWARD) |--Index Seek(OBJECT:([propertyControlCenter].[dbo].[Inventory].[IX_Inventory_Acct_ID] AS [I]), SEEK:([I].[Acct_ID]=(18731) AND [I].[Inv_ID]=[LOALogs].[dbo].[LogInvSearches_Daily].[Inv_ID] as [D].[Inv_ID]) ORDERED FORWARD) (8 row(s) affected) (1 row(s) affected) So given that I'm getting good Index Seeks in my execution plan, what can I do to get this running faster? Thanks, Dan

  Read the article

• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

  Read the article

• Log a user in to an ASP.net application using Windows Authentication without using Windows Authentic

  - by Rising Star

  I have an ASP.net application I'm developing authentication for. I am using an existing cookie-based log on system to log users in to the system. The application runs as an anonymous account and then checks the cookie when the user wants to do something restricted. This is working fine. However, there is one caveat: I've been told that for each page that connects to our SQL server, I need to make it so that the user connects using an Active Directory account. because the system I'm using is cookie based, the user isn't logged in to Active Directory. Therefore, I use impersonation to connect to the server as a specific account. However, the powers that be here don't like impersonation; they say that it clutters up the code. I agree, but I've found no way around this. It seems that the only way that a user can be logged in to an ASP.net application is by either connecting with Internet Explorer from a machine where the user is logged in with their Active Directory account or by typing an Active Directory username and password. Neither of these two are workable in my application. I think it would be nice if I could make it so that when a user logs in and receives the cookie (which actually comes from a separate log on application, by the way), there could be some code run which tells the application to perform all network operations as the user's Active Directory account, just as if they had typed an Active Directory username and password. It seems like this ought to be possible somehow, but the solution evades me. How can I make this work? Update To those who have responded so far, I apologize for the confusion I have caused. The responses I've received indicate that you've misunderstood the question, so please allow me to clarify. I have no control over the requirement that users must perform network operations (such as SQL queries) using Active Directory accounts. I've been told several times (online and in meat-space) that this is an unusual requirement and possibly bad practice. I also have no control over the requirement that users must log in using the existing cookie-based log on application. I understand that in an ideal MS ecosystem, I would simply dis-allow anonymous access in my IIS settings and users would log in using Windows Authentication. This is not the case. The current system is that as far as IIS is concerned, the user logs in anonymously (even though they supply credentials which result in the issuance of a cookie) and we must programmatically check the cookie to see if the user has access to any restricted resources. In times past, we have simply used a single SQL account to perform all queries. My direct supervisor (who has many years of experience with this sort of thing) wants to change this. He says that if each user has his own AD account to perform SQL queries, it gives us more of a trail to follow if someone tries to do something wrong. The closest thing I've managed to come up with is using WIF to give the user a claim to a specific Active Directory account, but I still have to use impersonation because even still, the ASP.net process presents anonymous credentials to the SQL server. It boils down to this: Can I log users in with Active Directory accounts in my ASP.net application without having the users manually enter their AD credentials? (Windows Authentication)

  Read the article

• N-tier Repository POCOs - Aggregates?

  - by Sam

  Assume the following simple POCOs, Country and State: public partial class Country { public Country() { States = new List<State>(); } public virtual int CountryId { get; set; } public virtual string Name { get; set; } public virtual string CountryCode { get; set; } public virtual ICollection<State> States { get; set; } } public partial class State { public virtual int StateId { get; set; } public virtual int CountryId { get; set; } public virtual Country Country { get; set; } public virtual string Name { get; set; } public virtual string Abbreviation { get; set; } } Now assume I have a simple respository that looks something like this: public partial class CountryRepository : IDisposable { protected internal IDatabase _db; public CountryRepository() { _db = new Database(System.Configuration.ConfigurationManager.AppSettings["DbConnName"]); } public IEnumerable<Country> GetAll() { return _db.Query<Country>("SELECT * FROM Countries ORDER BY Name", null); } public Country Get(object id) { return _db.SingleById(id); } public void Add(Country c) { _db.Insert(c); } /* ...And So On... */ } Typically in my UI I do not display all of the children (states), but I do display an aggregate count. So my country list view model might look like this: public partial class CountryListVM { [Key] public int CountryId { get; set; } public string Name { get; set; } public string CountryCode { get; set; } public int StateCount { get; set; } } When I'm using the underlying data provider (Entity Framework, NHibernate, PetaPoco, etc) directly in my UI layer, I can easily do something like this: IList<CountryListVM> list = db.Countries .OrderBy(c => c.Name) .Select(c => new CountryListVM() { CountryId = c.CountryId, Name = c.Name, CountryCode = c.CountryCode, StateCount = c.States.Count }) .ToList(); But when I'm using a repository or service pattern, I abstract away direct access to the data layer. It seems as though my options are to: Return the Country with a populated States collection, then map over in the UI layer. The downside to this approach is that I'm returning a lot more data than is actually needed. -or- Put all my view models into my Common dll library (as opposed to having them in the Models directory in my MVC app) and expand my repository to return specific view models instead of just the domain pocos. The downside to this approach is that I'm leaking UI specific stuff (MVC data validation annotations) into my previously clean POCOs. -or- Are there other options? How are you handling these types of things?

  Read the article

• surfaceDestroyed called out of turn

  - by Avasulthiris

  I'm currently developing on minimum sdk version 3 (Android 1.5 - cupcake) and I'm having a strange unexplained issue that I have not been able to solve on my own. It is now becoming a rather urgent issue as I've already missed 1 deadline... I'm writing a high-level library to make long term android development easier and quicker. The one specific module has to capture images for a application... I've gotten everything right so far over the last couple months, except this one little thing and I don't know what to do any more: When I use the Camera object and implement a SurfaceHolder.Callback, the methods surfaceCreated() and surfaceChanged() are called one after the other. Then when the activity finishes, surfaceDestroyed() is called. This is how it should be, but when I stick the exact same code in my library (plain Java library that references the Android API - not in an activity), surfaceDestroyed() is called directly after created and changed. As a result - the camera object is closed before I can use it and the application force closes. What a pain. I can't do anything! This method call is controlled by the device.. Why does the surface close for no reason? Even when I post it to run on the activity thread through my own invokeAndWait(Runnable) method, like I do for many other things. I have 5 different working examples of different ways and implementations of capturing images in android but I still get the same issue when I plug it into my library. I don't understand what the difference is. The code is pretty much the same - and I post all the related code to the UI thread so its not a thread handling issue or anything like that. I've rewritten it about 20 times in different ways - same issue every time.. The only other way to approach it that I know of is creating a new Camera and setting it to the VideoView. The android source (c++ native code) however provides no Camera constructor, only an open() method which automatically forwards the camera's state to 'prepared' but I can only set the camera to the VideoView from the 'initialized' state. Pretty silly, I know, but there is no way around it unless I modify the Android library source code haha. not an option! The API does not allow for this method - you are expected to use it like my first example. So essentially - i just need to understand exactly why surfaceDestroyed() is called out of turn and if there is anything I can do to avoid it closing? If i can just understand the exact logic behind it and how it works! The documentation isn't much help! Secondly, if someone knows of any alternative ways to do it, as my second example, but hopefully one which the API actually allows for? haha Thanks guys. I would post code, but its fairly complicated, a couple thousand lines for this specific class and it would probably take a couple days to explain with all the threading and event listeners and what not. I just need help with this 1 single thing. Please let me know if you have any questions.

  Read the article

• Organising XML results as cells in container (AS3)

  - by PJ Palomaki

  Hi, I'm having some problems figuring out how to organise data pulled off XML in cells within a container. I'm sure this should be a basic thing in AS3, but my head's fried.. can anyone help? Basically an array if fed to callThumbs() which iterates through it and compares the entries with preloaded XML _my_images. If match is found, it's sent to processXML which loads all relevant info and loads a .jpg thumbnail. All this is then fed to createCell which creates a specific cell with position values depending on x_counter and y_counter values (4 cells in a row) and adds the cell into a container _container_mc. The Problem: This all works fine and looks fine, the problem is that the cells within the container do not display in descending order. They are in random order, probably because some of the .jpg's takes longer to load etc. How do I easily organise the cells within the container in descending order by the XML .id value? Or how do I tell Flash to wait till the thumbnail and data is loaded and the cell created and added? Thanks guys, would really appreciate all the help! PJ //Flash (AS3) function callThumbs(_my_results:Array):void { // selector = 1 for specific items, 2 for search items var _thumb_url:XML; for (var r:Number=0; r < _my_results.length; r++) { // iterate through results vector, compare with _my_images XML .id for (var i:Number=0; i < _my_images.length(); i++) { if (_my_images[i][email protected]() == _my_results[r]) { _thumb_url=_my_images[i]; processXML(_thumb_url, i); } } } } // End callThumbs function processXML(imageXML:XML, num:Number) { // Processes XML data and loads .jpg thumbnail var _thumb_loader=new Loader(); _thumb_loader.load(new URLRequest("thumbs/thumb_sm/" + imageXML.@id + "_st.jpg")); _thumb_loader.contentLoaderInfo.addEventListener(Event.COMPLETE,thumbLoaded); _thumb_loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, urlNotFound); var id:XMLList = new XMLList; id = imageXML.@id; var description:XMLList = new XMLList; description = imageXML.@description; function urlNotFound(event:IOErrorEvent):void { trace("The image URL '" + String(imageXML.@id) + "' was not found."); } function thumbLoaded(e:Event):void { var imageLoader:Loader = Loader(e.target.loader); var bm:Bitmap = Bitmap(imageLoader.content); createCell(bm, id, description, num); adjustFooterBar(); // Adjust bottom footer } } // End processXML private function createCell(_image:Bitmap, _id, _description:String, _position):void { // Creates a cell with data, add to container var _cell_mc = new CellTitle(); _cell_mc.initCell(_image, _id, _description, _position, x_counter, y_counter); if (x_counter+1 < 4) { x_counter++; } else { x_counter = 0; y_counter++; } _container_mc.addChild(_cell_mc); // movieclip container } // End createCell

  Read the article

• Apache/PHP serving file multiple times

  - by easement

  I have a system with a download.php page. The page takes and id and loads a file based on from the DB Record and then serves it up. I've noticed a couple instances where files are requested multiple times in short time spans (20ms). Times that are too quick for human input. There are plenty of instances where the downloader functions fine. However, in taking a closer look at the downloader’s usage, I did see some interesting behavior. For instance, the IP address xxx.xxx.xxx.xxx (which is one in a range owned by xxxxxx.de in Germany) came to the site through Google. They browsed around and then came to the page http://site.com/xxxx/press+125.php There they issued a request for /download.php?id=/ZZ/n+aH55Y= (a PDF) at 9:04:23AM. That alone is not a big deal. However, what is interesting is that the server seems to have been quite preoccupied with serving that request. In the logs the request first completes between 9:09:48 and 9:10:00. It looks like the user must have gotten tired of waiting during that time and requested the document two more times. Between 09:14:47 and 09:15:00 the same request appears again, except it is from 9:04:43AM, 20ms later than the first request. Then it pops up a third time, with a request that started at 09:05:06 completing between 09:19:55 and 09:19:58! I’m suspicious of that document. In looking through the logs I see other instances where it takes the server a little while to handle that specific file. Check out this list of requests from zzz.zzz.zzz.zzz[different than above] for the file /download.php?id=/ZZ/n+aH55Y= (the same docuemnt as before): Request time Complete Time 04:32:43 04:33:36 04:32:50 04:33:36 04:32:51 04:33:38 04:33:05 04:33:38 04:33:34 04:33:42 04:33:05 04:33:42 So something is definitely going on. Whether it has to do with this specific document tripping up the server, the download.php page’s code, or if we’re just seeing the evidence of some server level overload as it plays out in real time I’m not yet sure. In fairness, there are other instances of people downloading /download.php?id=/ZZ/n+aH55Y= (the same PDF) without error. However, it is interesting that the multiple processes only seem to happen with this one file, and then only when it is accessed through the page http://site.com/press+125.php . It bears further investigation if there’s something amiss inside the code that causes the system to fire off multiple download requests that occupy the server. I don't know if this press+125.php is a rabbit hole, but there is weird consicence. Any ideas? I'm totally out of ideas. Apache maxed out? Things like that. ///DOWNLOAD.php $file = new files(); $file->comparison_filter("id", "=", $id); //sql to load if ($file->load()) { $file->serve(); } //FILES function serve() { if ($this->is_loaded) { if (file_exists($this->get_value("filename"))) { if ($this->get_value("content_type") != "") { header("Content-Type: " . $this->get_value("content_type")); } header("Content-Length: " . filesize($this->get_value("filename"))); if ($this->get_value("flag_image") == 0 || $this->get_value("flag_image") == false) { header("Cache-Control: private"); header("Content-Disposition: attachment; filename=" . urlencode($this->get_value("original_filename"))); } set_time_limit(0); @readfile($this->get_value("filename")); exit; } } }

  Read the article

• What's the best way to refactor this Rails controller?

  - by Robert DiNicolas

  I'd like some advice on how to best refactor this controller. The controller builds a page of zones and modules. Page has_many zones, zone has_many modules. So zones are just a cluster of modules wrapped in a container. The problem I'm having is that some modules may have some specific queries that I don't want executed on every page, so I've had to add conditions. The conditions just test if the module is on the page, if it is the query is executed. One of the problems with this is if I add a hundred special module queries, the controller has to iterate through each one. I think I would like to see these module condition moved out of the controller as well as all the additional custom actions. I can keep everything in this one controller, but I plan to have many apps using this controller so it could get messy. class PagesController < ApplicationController # GET /pages/1 # GET /pages/1.xml # Show is the main page rendering action, page routes are aliased in routes.rb def show #-+-+-+-+-Core Page Queries-+-+-+-+- @page = Page.find(params[:id]) @zones = @page.zones.find(:all, :order => 'zones.list_order ASC') @mods = @page.mods.find(:all) @columns = Page.columns # restful params to influence page rendering, see routes.rb @fragment = params[:fragment] # render single module @cluster = params[:cluster] # render single zone @head = params[:head] # render html, body and head #-+-+-+-+-Page Level Json Conversions-+-+-+-+- @metas = @page.metas ? ActiveSupport::JSON.decode(@page.metas) : nil @javascripts = @page.javascripts ? ActiveSupport::JSON.decode(@page.javascripts) : nil #-+-+-+-+-Module Specific Queries-+-+-+-+- # would like to refactor this process @mods.each do |mod| # Reps Module Custom Queries if mod.name == "reps" @reps = User.find(:all, :joins => :roles, :conditions => { :roles => { :name => 'rep' } }) end # Listing-poc Module Custom Queries if mod.name == "listing-poc" limit = params[:limit].to_i < 1 ? 10 : params[:limit] PropertyEntry.update_from_listing(mod.service_url) @properties = PropertyEntry.all(:limit => limit, :order => "city desc") end # Talents-index Module Custom Queries if mod.name == "talents-index" @talent = params[:type] @reps = User.find(:all, :joins => :talents, :conditions => { :talents => { :name => @talent } }) end end respond_to do |format| format.html # show.html.erb format.xml { render :xml => @page.to_xml( :include => { :zones => { :include => :mods } } ) } format.json { render :json => @page.to_json } format.css # show.css.erb, CSS dependency manager template end end # for property listing ajax request def update_properties limit = params[:limit].to_i < 1 ? 10 : params[:limit] offset = params[:offset] @properties = PropertyEntry.all(:limit => limit, :offset => offset, :order => "city desc") #render :nothing => true end end So imagine a site with a hundred modules and scores of additional controller actions. I think most would agree that it would be much cleaner if I could move that code out and refactor it to behave more like a configuration.

  Read the article

• [C] Texture management / pointer question

  - by ndg

  I'm working on a texture management and animation solution for a small side project of mine. Although the project uses Allegro for rendering and input, my question mostly revolves around C and memory management. I wanted to post it here to get thoughts and insight into the approach, as I'm terrible when it comes to pointers. Essentially what I'm trying to do is load all of my texture resources into a central manager (textureManager) - which is essentially an array of structs containing ALLEGRO_BITMAP objects. The textures stored within the textureManager are mostly full sprite sheets. From there, I have an anim(ation) struct, which contains animation-specific information (along with a pointer to the corresponding texture within the textureManager). To give you an idea, here's how I setup and play the players 'walk' animation: createAnimation(&player.animations[0], "media/characters/player/walk.png", player.w, player.h); playAnimation(&player.animations[0], 10); Rendering the animations current frame is just a case of blitting a specific region of the sprite sheet stored in textureManager. For reference, here's the code for anim.h and anim.c. I'm sure what I'm doing here is probably a terrible approach for a number of reasons. I'd like to hear about them! Am I opening myself to any pitfalls? Will this work as I'm hoping? anim.h #ifndef ANIM_H #define ANIM_H #define ANIM_MAX_FRAMES 10 #define MAX_TEXTURES 50 struct texture { bool active; ALLEGRO_BITMAP *bmp; }; struct texture textureManager[MAX_TEXTURES]; typedef struct tAnim { ALLEGRO_BITMAP **sprite; int w, h; int curFrame, numFrames, frameCount; float delay; } anim; void setupTextureManager(void); int addTexture(char *filename); int createAnimation(anim *a, char *filename, int w, int h); void playAnimation(anim *a, float delay); void updateAnimation(anim *a); #endif anim.c void setupTextureManager() { int i = 0; for(i = 0; i < MAX_TEXTURES; i++) { textureManager[i].active = false; } } int addTextureToManager(char *filename) { int i = 0; for(i = 0; i < MAX_TEXTURES; i++) { if(!textureManager[i].active) { textureManager[i].bmp = al_load_bitmap(filename); textureManager[i].active = true; if(!textureManager[i].bmp) { printf("Error loading texture: %s", filename); return -1; } return i; } } return -1; } int createAnimation(anim *a, char *filename, int w, int h) { int textureId = addTextureToManager(filename); if(textureId > -1) { a->sprite = textureManager[textureId].bmp; a->w = w; a->h = h; a->numFrames = al_get_bitmap_width(a->sprite) / w; printf("Animation loaded with %i frames, given resource id: %i\n", a->numFrames, textureId); } else { printf("Texture manager full\n"); return 1; } return 0; } void playAnimation(anim *a, float delay) { a->curFrame = 0; a->frameCount = 0; a->delay = delay; } void updateAnimation(anim *a) { a->frameCount ++; if(a->frameCount >= a->delay) { a->frameCount = 0; a->curFrame ++; if(a->curFrame >= a->numFrames) { a->curFrame = 0; } } }

  Read the article

• How to extract comment out of header file using python, perl, or sed?

  - by WilliamKF

  I have a header file like this: /* * APP 180-2 ALG-254/258/772 implementation * Last update: 03/01/2006 * Issue date: 08/22/2004 * * Copyright (C) 2006 Somebody's Name here * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef HEADER_H #define HEADER_H /* More comments and C++ code here. */ #endif /* End of file. */ And I wish to extract out the contents of the first C style comment only and drop the " *" at the start of each line to get a file with the following contents: APP 180-2 ALG-254/258/772 implementation Last update: 03/01/2006 Issue date: 08/22/2004 Copyright (C) 2006 Somebody's Name here All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the project nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Please suggest an easy way to do this with Python, Perl, sed, or some other way on Unix. Preferably as a one-liner.

  Read the article

• Receiving Multicast Messages on a Multihomed Windows PC

  - by Basti

  I'm developing a diagnostic tool on a PC with several Network Interfaces based on multicast/udp. The user can select a NIC, the application creates sockets, binds them to this NIC and adds them to the specific multicast group. The sending of multicast messages works fine. However receiving of messages only succeeds if I bind the sockets to a specific NIC of my PC. It almost looks like as there is a 'default' NIC for receiving multicast messages in Windows which is always the first NIC returned by the GetAdapterInfo function. I monitored the network with Wireshark and discovered that the "IGMP Join Group" message isn't sent from the NIC I bound the socket at, but by this 'default' NIC. If I disable this NIC (or remove the network cable), the next NIC of the list returned by GetAdapterInfo is used for receiving multicast messages. I was successful to change this 'default' NIC by adding an additional entry to the routing table of my PC, but I don't think this is a good solution of the problem. The problem also occurs with the code appended below. The join group messages isn't sent via 192.168.52 but via a different NIC. // socket_tst.cpp : Defines the entry point for the console application. // #include tchar.h #include winsock2.h #include ws2ipdef.h #include IpHlpApi.h #include IpTypes.h #include stdio.h int _tmain(int argc, _TCHAR* argv[]) { WSADATA m_wsaData; SOCKET m_socket; sockaddr_in m_sockAdr; UINT16 m_port = 319; u_long m_interfaceAdr = inet_addr("192.168.1.52"); u_long m_multicastAdr = inet_addr("224.0.0.107"); int returnValue = WSAStartup(MAKEWORD(2,2), &m_wsaData); if (returnValue != S_OK) { return returnValue; } // Create sockets if (INVALID_SOCKET == (m_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) ) { return WSAGetLastError(); } int doreuseaddress = TRUE; if (setsockopt(m_socket,SOL_SOCKET,SO_REUSEADDR,(char*) &doreuseaddress,sizeof(doreuseaddress)) == SOCKET_ERROR) { return WSAGetLastError(); } // Configure socket addresses memset(&m_sockAdr,0,sizeof(m_sockAdr)); m_sockAdr.sin_family = AF_INET; m_sockAdr.sin_port = htons(m_port); m_sockAdr.sin_addr.s_addr = m_interfaceAdr; //bind sockets if ( bind( m_socket, (SOCKADDR*) &m_sockAdr, sizeof(m_sockAdr) ) == SOCKET_ERROR ) { return WSAGetLastError(); } // join multicast struct ip_mreq_source imr; memset(&imr,0,sizeof(imr)); imr.imr_multiaddr.s_addr = m_multicastAdr; // address of multicastgroup imr.imr_sourceaddr.s_addr = 0; // sourceaddress (not used) imr.imr_interface.s_addr = m_interfaceAdr; // interface address /* first join multicast group, then registerer selected interface as * multicast sending interface */ if( setsockopt( m_socket ,IPPROTO_IP ,IP_ADD_MEMBERSHIP ,(char*) &imr , sizeof(imr)) == SOCKET_ERROR) { return SOCKET_ERROR; } else { if( setsockopt(m_socket ,IPPROTO_IP ,IP_MULTICAST_IF ,(CHAR*)&imr.imr_interface.s_addr ,sizeof(&imr.imr_interface.s_addr)) == SOCKET_ERROR ) { return SOCKET_ERROR; } } printf("receiving msgs...\n"); while(1) { // get inputbuffer from socket int sock_return = SOCKET_ERROR; sockaddr_in socketAddress; char buffer[1500]; int addressLength = sizeof(socketAddress); sock_return = recvfrom(m_socket, (char*) &buffer, 1500, 0, (SOCKADDR*)&socketAddress, &addressLength ); if( sock_return == SOCKET_ERROR) { int wsa_error = WSAGetLastError(); return wsa_error; } else { printf("got message!\n"); } } return 0; } Thanks four your help!

  Read the article

• Delaying execution of Javascript function relative to Google Maps / geoxml3 parser?

  - by Terra Fimeira

  I'm working on a implementing a Google map on a website with our own tiles overlays and KML elements. I've been previously requested to create code so that, for instance, when the page is loaded from a specific URL, it would initialize with one of the tile overlays already enabled. Recently, I've been requested to do the same for the buildings which are outlined by KML elements so that, arriving at the page with a specific URL, it would automatically zoom, center, and display information on the building. However, while starting with the tile overlays work, the building KML does not. After doing some testing, I've determined that when the code which checks the URL executes, the page is still loading the KML elements and thus do not exist for the code to compare to or use: Code for evaluating URL (placed at the end of onLoad="initialize()") function urlClick() { var currentURL = window.location.href; //Retrieve page URL var URLpiece = currentURL.slice(-6); //pull the last 6 digits (for testing) if (URLpiece === "access") { //If the resulting string is "access": access_click(); //Display accessibility overlay } else if (URLpiece === "middle") { //Else if the string is "middle": facetClick('Middle College'); //Click on building "Middle College" }; }; facetClick(); function facetClick(name) { //Convert building name to building ID. for (var i = 0; i < active.placemarks.length; i++) { if (active.placemarks[i].name === name) { sideClick(i) //Click building whose id matches "Middle College" }; }; }; Firebug Console Error active is null for (var i = 0; i < active.placemarks.length; i++) { active.placemarks is which KML elements are loaded on the page, and being null, means no KML has been loaded yet. In short, I have a mistiming and I can't seem to find a suitable place to place the URL code to execute after the KMl has loaded. As noted above, I placed it at the end of onLoad="initialize()", but it would appear that, instead of waiting for the KML to completely load earlier in the function, the remainder of the function is executed: onLoad="initialize()" information(); //Use the buttons variables inital state to set up description buttons(); //and button state button_hover(0); //and button description to neutral. //Create and arrange the Google Map. //Create basic tile overlays. //Set up parser to work with KML elements. myParser = new geoXML3.parser({ //Parser: Takes KML and converts to JS. map: map, //Applies parsed KML to the map singleInfoWindow: true, afterParse: useTheData //Allows us to use the parsed KML in a function }); myParser.parse(['/maps/kml/shapes.kml','/maps/kml/shapes_hidden.kml']); google.maps.event.addListener(map, 'maptypeid_changed', function() { autoOverlay(); }); //Create other tile overlays to appear over KML elements. urlClick(); I suspect one my issues lies in using the geoxml3 parser (http://code.google.com/p/geoxml3/) which converts our KML files to Javascript. While the page has completed loading all of the elements, the map on the page is still loading, including the KML elements. I have also tried placing urlClick() in the parser itself in various places which appear to execute after all the shapes have been parsed, but I've had no success there either. While I've been intending to strip out the parser, I would like to know if there is any way of executing the "urlClick" after the parser has returned the KML shapes. Ideally, I don't want to use an arbitrary means of defining a time to wait, such as "wait 3 seconds, and go", as my various browsers all load the page at different times; rather, I'm looking for some way to say "when the parser is done, execute" or "when the Google map is completely loaded, execute" or perhaps even "hold until the parser is complete before advancing to urlClick".

  Read the article

• PHP - Code Sample - Polymorphism Implementation - How to allow for expansion?

  - by darga33

  I've read numerous SO posts about Polymorphism, and also the other really good one at http://net.tutsplus.com/tutorials/php/understanding-and-applying-polymorphism-in-php/ Good stuff!!! I'm trying to figure out how a seasoned PHP developer that follows all the best practices would accomplish the following. Please be as specific and detailed as possible. I'm sure your answer is going to help a lot of people!!! :-) While learning Polymorphism, I came across a little stumbling block. Inside of the PDFFormatter class, I had to use (instanceof) in order to figure out if some code should be included in the returned data. I am trying to be able to pass in two different kinds of profiles to the formatter. (needs to be able to handle multiple kinds of formatters but display the data specific to the Profile class that is being passed to it). It doesn't look bad now, but imagine 10 more kinds of Profiles!! How would you do this? The best answer would also include the changes you would make. Thanks sooooooo much in advance!!!!! Please PHP only! Thx!!! File 1. FormatterInterface.php interface FormatterInterface { public function format(Profile $Profile); } File 2. PDFFormatter.php class PDFFormatter implements FormatterInterface { public function format(Profile $Profile) { $format = "PDF Format<br /><br />"; $format .= "This is a profile formatted as a PDF.<br />"; $format .= 'Name: ' . $Profile->name . '<br />'; if ($Profile instanceof StudentProfile) { $format .= "Graduation Date: " . $Profile->graduationDate . "<br />"; } $format .= "<br />End of PDF file"; return $format; } } File 3. Profile.php class Profile { public $name; public function __construct($name) { $this->name = $name; } public function format(FormatterInterface $Formatter) { return $Formatter->format($this); } } File 4. StudentProfile.php class StudentProfile extends Profile { public $graduationDate; public function __construct($name, $graduationDate) { $this->name = $name; $this->graduationDate = $graduationDate; } } File 5. index.php //Assuming all files are included...... $StudentProfile = new StudentProfile('Michael Conner', 55, 'Unknown, FL', 'Graduate', '1975', 'Business Management'); $Profile = new Profile('Brandy Smith', 44, 'Houston, TX'); $PDFFormatter = new PDFFormatter(); echo '<hr />'; echo $StudentProfile->format($PDFFormatter); echo '<hr />'; echo $Profile->format($PDFFormatter);

  Read the article

• (SQL) Selecting from a database based on multiple pairs of pairs

  - by Owen Allen

  The problem i've encountered is attempting to select rows from a database where 2 columns in that row align to specific pairs of data. IE selecting rows from data where id = 1 AND type = 'news'. Obviously, if it was 1 simple pair it would be easy, but the issue is we are selecting rows based on 100s of pair of data. I feel as if there must be some way to do this query without looping through the pairs and querying each individually. I'm hoping some SQL stackers can provide guidance. Here's a full code break down: Lets imagine that I have the following dataset where history_id is the primary key. I simplified the structure a bit regarding the dates for ease of reading. table: history history_id id type user_id date 1 1 news 1 5/1 2 1 news 1 5/1 3 1 photo 1 5/2 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 If the user wants to select rows from the database based on a date range we would take a subset of that data. SELECT history_id, id, type, user_id, date FROM history WHERE date BETWEEN '5/3' AND '5/5' Which returns the following dataset history_id id type user_id date 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 Now, using that subset of data I need to determine how many of those entries represent the first entry in the database for each type,id pairing. IE is row 4 the first time in the database that id: 3, type: news appears. So I use a with() min() query. In real code the two lists are programmatically generated from the result sets of our previous query, here I spelled them out for ease of reading. WITH previous AS ( SELECT history_id, id, type FROM history WHERE id IN (1,2,3,4) AND type IN ('news','photo') ) SELECT min(history_id) as history_id, id, type FROM previous GROUP BY id, type Which returns the following data set. history_id id type user_id date 1 1 news 1 5/1 2 1 news 1 5/1 3 1 photo 1 5/2 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 You'll notice it's the entire original dataset, because we are matching id and type individually in lists, rather than as a collective pairs. The result I desire is, but I can't figure out the SQL to get this result. history_id id type user_id date 1 1 news 1 5/1 4 3 news 1 5/3 5 4 news 1 5/3 7 2 photo 1 5/4 Obviously, I could go the route of looping through each pair and querying the database to determine it's first result, but that seems an inefficient solution. I figured one of the SQL gurus on this site might be able to spread some wisdom. In case I'm approaching this situation incorrectly, the gist of the whole routine is that the database stores all creations and edits in the same table. I need to track each users behavior and determine how many entries in the history table are edits or creations over a specific date range. Therefore I select all type:id pairs from the date range based on a user_id, and then for each pairing I determine if the user is responsible for the first that occurs in the database. If first, then creation else edit. Any assistance would be awesome.

  Read the article

• "FOR UPDATE" v/s "LOCK IN SHARE MODE" : Allow concurrent threads to read updated "state" value of locked row

  - by shadesco

  I have the following scenario: User X logs in to the application from location lc1: call it Ulc1 User X (has been hacked, or some friend of his knows his login credential, or he just logs in from a different browser on his machine,etc.. u got the point) logs in at the same time from location lc2: call it Ulc2 I am using a main servlet which : - gets a connection from database pooling - sets autocommit to false - executes a command that goes through app layers: if all successful, set autocommit to true in a "finally" statement, and closes connection. Else if an exception happens, rollback(). In my database (mysql/innoDb) i have a "history" table, with row columns: id(primary key) |username | date | topic | locked The column "locked" has by default value "false" and it serves as a flag that marks if a specific row is locked or not. Each row is specific to a user (as u can see from the username column) So back to the scenario: --Ulc1 sends the command to update his history from the db for date "D" and topic "T". --Ulc2 sends the same command to update history from the db for the same date "D" and same topic "T" at the exact same time. I want to implement an mysql/innoDB locking system that will enable whichever thread arriving to do the following check: Is column "locked" for this row true or not? if true, return a message to the user that " he is already updating the same data from another location" if not true (ie not locked) : flag it as locked and update then reset locked to false once finished. Which of these two mysql locking techniques, will actually allow the 2nd arriving thread from reading the "updated" value of the locked column to decide wt action to take?Should i use "FOR UPDATE" or "LOCK IN SHARE MODE"? This scenario explains what i want to accomplish: - Ulc1 thread arrives first: column "locked" is false, set it to true and continue updating process - Ulc2 thread arrives while Ulc1's transaction is still in process, and even though the row is locked through innoDb functionalities, it doesn't have to wait but in fact reads the "new" value of column locked which is "true", and so doesn't in fact have to wait till Ulc1 transaction commits to read the value of the "locked" column(anyway by that time the value of this column will already have been reset to false). I am not very experienced with the 2 types of locking mechanisms, what i understand so far is that LOCK IN SHARE MODE allow other transaction to read the locked row while FOR UPDATE doesn't even allow reading. But does this read gets on the updated value? or the 2nd arriving thread has to wait the first thread to commit to then read the value? Any recommendations about which locking mechanism to use for this scenario is appreciated. Also if there's a better way to "check" if the row has been locked (other than using a true/false column flag) please let me know about it. thank you SOLUTION (Jdbc pseudocode example based on @Darhazer's answer) Table : [ id(primary key) |username | date | topic | locked ] connection.setautocommit(false); //transaction-1 PreparedStatement ps1 = "Select locked from tableName for update where id="key" and locked=false); ps1.executeQuery(); //transaction 2 PreparedStatement ps2 = "Update tableName set locked=true where id="key"; ps2.executeUpdate(); connection.setautocommit(true);// here we allow other transactions threads to see the new value connection.setautocommit(false); //transaction 3 PreparedStatement ps3 = "Update tableName set aField="Sthg" where id="key" And date="D" and topic="T"; ps3.executeUpdate(); // reset locked to false PreparedStatement ps4 = "Update tableName set locked=false where id="key"; ps4.executeUpdate(); //commit connection.setautocommit(true);

  Read the article

• Keeping video viewing statistics breakdown by video time in a database

  - by Septagram

  I need to keep a number of statistics about the videos being watched, and one of them is what parts of the video are being watched most. The design I came up with is to split the video into 256 intervals and keep the floating-point number of views for each of them. I receive the data as a number of intervals the user watched continuously. The problem is how to store them. There are two solutions I see. Row per every video segment Let's have a database table like this: CREATE TABLE `video_heatmap` ( `id` int(11) NOT NULL AUTO_INCREMENT, `video_id` int(11) NOT NULL, `position` tinyint(3) unsigned NOT NULL, `views` float NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `idx_lookup` (`video_id`,`position`) ) ENGINE=MyISAM Then, whenever we have to process a number of views, make sure there are the respective database rows and add appropriate values to the views column. I found out it's a lot faster if the existence of rows is taken care of first (SELECT COUNT(*) of rows for a given video and INSERT IGNORE if they are lacking), and then a number of update queries is used like this: UPDATE video_heatmap SET views = views + ? WHERE video_id = ? AND position >= ? AND position < ? This seems, however, a little bloated. The other solution I came up with is Row per video, update in transactions A table will look (sort of) like this: CREATE TABLE video ( id INT NOT NULL AUTO_INCREMENT, heatmap BINARY (4 * 256) NOT NULL, ... ) ENGINE=InnoDB Then, upon every time a view needs to be stored, it will be done in a transaction with consistent snapshot, in a sequence like this: If the video doesn't exist in the database, it is created. A row is retrieved, heatmap, an array of floats stored in the binary form, is converted into a form more friendly for processing (in PHP). Values in the array are increased appropriately and the array is converted back. Row is changed via UPDATE query. So far the advantages can be summed up like this: First approach Stores data as floats, not as some magical binary array. Doesn't require transaction support, so doesn't require InnoDB, and we're using MyISAM for everything at the moment, so there won't be any need to mix storage engines. (only applies in my specific situation) Doesn't require a transaction WITH CONSISTENT SNAPSHOT. I don't know what are the performance penalties of those. I already implemented it and it works. (only applies in my specific situation) Second approach Is using a lot less storage space (the first approach is storing video ID 256 times and stores position for every segment of the video, not to mention primary key). Should scale better, because of InnoDB's per-row locking as opposed to MyISAM's table locking. Might generally work faster because there are a lot less requests being made. Easier to implement in code (although the other one is already implemented). So, what should I do? If it wasn't for the rest of our system using MyISAM consistently, I'd go with the second approach, but currently I'm leaning to the first one. But maybe there are some reasons to favour one approach or another?

  Read the article

< Previous Page | 603 604 605 606 607 608 609 610 611 612 613 614  | Next Page >