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• determine collision angle on a rotating body

  - by jorb

  update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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• Why doesn't the monitor output anything in Linux console mode?

  - by flypen

  I install Linux without graphics support. Previously I used a monitor with 720p support. And it can display normally. Now I change to a monitor with 1080p support. I can see BIOS and GRUB info on monitor, and kernel messages in early stages. However, the monitor says that there is no input immediately, and then I can't see anything again. It seems that it happens after something initializes. Is it related to vesafb? vesafb: mode is 1280x1024x32, linelength=5120, pages=0 vesafb: scrolling: redraw vesafb: Truecolor: size=8:8:8:8, shift=24:16:8:0 mtrr: type mismatch for 7f800000,800000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,400000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,200000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,100000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,80000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,40000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,20000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,10000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,8000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,4000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,2000 old: write-back new: write-combining mtrr: type mismatch for 7f800000,1000 old: write-back new: write-combining vesafb: framebuffer at 0x7f800000, mapped to 0xffffc90011380000, using 5120k, total 5120k Console: switching to colour frame buffer device 160x64 fb0: VESA VGA frame buffer device

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• Centos 5.xx Nagios sSMTP mail cannot be sent from nagios server, but works great from console

  - by adam

  I spent last 3 hours of reasearch on how to get nagios to work with email notifications, i need to send emails form work where the only accesible smtp server is the company's one. i managed to get it done from the console using: mail [email protected] working perfectly for the purpouse i set up ssmtp.conf so as: [email protected] mailhub=smtp.company.com:587 [email protected] AuthPass=mypassword FromLineOverride=YES useSTARTTLS=YES rewriteDomain=company.pl hostname=nagios UseTLS=YES i also edited the file /etc/ssmtp/revaliases so as: root:[email protected]:smtp.company.com:587 nagios:[email protected]:smtp.company.com:587 nagiosadmin:[email protected]:smtp.company.com:587 i also edited the file permisions for /etc/ssmtp/* so as: -rwxrwxrwx 1 root nagios 371 lis 22 15:27 /etc/ssmtp/revaliases -rwxrwxrwx 1 root nagios 1569 lis 22 17:36 /etc/ssmtp/ssmtp.conf and i assigned to proper groups i belive: cat /etc/group |grep nagios mail:x:12:mail,postfix,nagios mailnull:x:47:nagios nagios:x:2106:nagios nagcmd:x:2107:nagios when i send mail manualy, i recieve it on my priv box, but when i send mail from nagios the mail log says: Nov 22 17:47:03 certa-vm2 sSMTP[9099]: MAIL FROM:<[email protected]> Nov 22 17:47:03 certa-vm2 sSMTP[9099]: 550 You are not allowed to send mail from this address it says [email protected] and im not allowed to send mails claiming to be [email protected], its suppoused to be [email protected], what am i doing wrong? i ran out of tricks... kind regards Adam xxxx

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• Datastage 8.7 installs fine on Window7 without any errors but it can not launch localhost:9080 web console

  - by user265273

  When I launch the web console, I get page can not be displayed error. What I have tried so far: I have re-installed DS about 7 times, and each time, I get same errors. I added entries in etc/hosts file for local host and my host name. I have turned off firewall. My hardware/software setup. My host system is window8.1. My vmware workstation is 7. The guest os is windows 7 enterprise x64. I have installed 10g, and given dba role to public. I have installed VS 5, and ms visual c++ 2010 express. I have installed msxml. IE version is 10. Firewall is off. My internet works fine It passed all the DS requirement tests and install completed successfully. When I launch my vmware guest instance, I do get SQL5000c error upon boot which I have tried to ignore in some installs and in some, I used db2systray -clean command to get rid of it. But that has not helped solve the webconsole connect failure to my host. I have spent over 2 weeks exclusively on this issue and badly need some help.

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• How can I tell System Restore in WIndows 7 recovery console to use my recovered backup drive's restore point data?

  - by Rich Shealer

  My Windows 7 desktop PC failed to boot. It would get to a grayish screen with a mouse and would only respond to the power button. After much examination I found that the problem was not a failed drive as running CHKDSK from the Recovery Console on my main drives passed without any errors. I had been installing various Java version in the days before the failure so I decided to use a restore point to roll backwards. I have an external SATA drive controller with two 2 TB drives mirrored using the Windows mirroring function. My system has been backing up to this drive regularly. The problem is I accidently broke the mirror when testing to see if this drive system might have been causing my boot issue. Connecting it to another machine showed two dynamic drives that were invalid. In the end I reformatted one as an NTFS basic disc and used recovery software on the other to copy all of the files to the reformatted drive. I had to copy the restore points into the new drive's System Volume Information folder by granting rights to that user. I moved the drive back to the original machine and rebooted. I can see my new drive, it even uses the same drive letter as it did in normal mode. Running System Restore it lists a new Automatic Restore point created while sitting at the RC along with all of my backups. Selecting the backup I want (or any other) I get a dialog. The backup drive could not be found. System Restore is looking for restore points on your backup. Make sure the backup drive is on and connected to this computer and then click OK. What do I need to do to allow system restore to see the restore points?

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• XmlSerializer throws exception when serializing dynamically loaded type

  - by Dr. Sbaitso

  Hi I'm trying to use the System.Xml.Serialization.XmlSerializer to serialize a dynamically loaded (and compiled class). If I build the class in question into the main assembly, everything works as expected. But if I compile and load the class from an dynamically loaded assembly, the XmlSerializer throws an exception. What am I doing wrong? I've created the following .NET 3.5 C# application to reproduce the issue: using System; using System.Collections.Generic; using System.Xml.Serialization; using System.Text; using System.Reflection; using System.CodeDom.Compiler; using Microsoft.CSharp; public class StaticallyBuiltClass { public class Item { public string Name { get; set; } public int Value { get; set; } } private List<Item> values = new List<Item>(); public List<Item> Values { get { return values; } set { values = value; } } } static class Program { static void Main() { RunStaticTest(); RunDynamicTest(); } static void RunStaticTest() { Console.WriteLine("-------------------------------------"); Console.WriteLine(" Serializing StaticallyBuiltClass..."); Console.WriteLine("-------------------------------------"); var stat = new StaticallyBuiltClass(); Serialize(stat.GetType(), stat); Console.WriteLine(); } static void RunDynamicTest() { Console.WriteLine("-------------------------------------"); Console.WriteLine(" Serializing DynamicallyBuiltClass..."); Console.WriteLine("-------------------------------------"); CSharpCodeProvider csProvider = new CSharpCodeProvider(new Dictionary<string, string> { { "CompilerVersion", "v3.5" } }); CompilerParameters csParams = new System.CodeDom.Compiler.CompilerParameters(); csParams.GenerateInMemory = true; csParams.GenerateExecutable = false; csParams.ReferencedAssemblies.Add("System.dll"); csParams.CompilerOptions = "/target:library"; StringBuilder classDef = new StringBuilder(); classDef.AppendLine("using System;"); classDef.AppendLine("using System.Collections.Generic;"); classDef.AppendLine(""); classDef.AppendLine("public class DynamicallyBuiltClass"); classDef.AppendLine("{"); classDef.AppendLine(" public class Item"); classDef.AppendLine(" {"); classDef.AppendLine(" public string Name { get; set; }"); classDef.AppendLine(" public int Value { get; set; }"); classDef.AppendLine(" }"); classDef.AppendLine(" private List<Item> values = new List<Item>();"); classDef.AppendLine(" public List<Item> Values { get { return values; } set { values = value; } }"); classDef.AppendLine("}"); CompilerResults res = csProvider.CompileAssemblyFromSource(csParams, new string[] { classDef.ToString() }); foreach (var line in res.Output) { Console.WriteLine(line); } Assembly asm = res.CompiledAssembly; if (asm != null) { Type t = asm.GetType("DynamicallyBuiltClass"); object o = t.InvokeMember("", BindingFlags.CreateInstance, null, null, null); Serialize(t, o); } Console.WriteLine(); } static void Serialize(Type type, object o) { var serializer = new XmlSerializer(type); try { serializer.Serialize(Console.Out, o); } catch(Exception ex) { Console.WriteLine("Exception caught while serializing " + type.ToString()); Exception e = ex; while (e != null) { Console.WriteLine(e.Message); e = e.InnerException; Console.Write("Inner: "); } Console.WriteLine("null"); Console.WriteLine(); Console.WriteLine("Stack trace:"); Console.WriteLine(ex.StackTrace); } } } which generates the following output: ------------------------------------- Serializing StaticallyBuiltClass... ------------------------------------- <?xml version="1.0" encoding="IBM437"?> <StaticallyBuiltClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Values /> </StaticallyBuiltClass> ------------------------------------- Serializing DynamicallyBuiltClass... ------------------------------------- Exception caught while serializing DynamicallyBuiltClass There was an error generating the XML document. Inner: The type initializer for 'Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterDynamicallyBuiltClass' threw an exception. Inner: Object reference not set to an instance of an object. Inner: null Stack trace: at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id) at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces) at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o) at Program.Serialize(Type type, Object o) in c:\dev\SerTest\SerTest\Program.cs:line 100 Edit: Removed some extraneous referenced assemblies

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• How LINQ to Object statements work

  - by rajbk

  This post goes into detail as to now LINQ statements work when querying a collection of objects. This topic assumes you have an understanding of how generics, delegates, implicitly typed variables, lambda expressions, object/collection initializers, extension methods and the yield statement work. I would also recommend you read my previous two posts: Using Delegates in C# Part 1 Using Delegates in C# Part 2 We will start by writing some methods to filter a collection of data. Assume we have an Employee class like so: 1: public class Employee { 2: public int ID { get; set;} 3: public string FirstName { get; set;} 4: public string LastName {get; set;} 5: public string Country { get; set; } 6: } and a collection of employees like so: 1: var employees = new List<Employee> { 2: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 3: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 4: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 5: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" }, 6: }; Filtering We wish to  find all employees that have an even ID. We could start off by writing a method that takes in a list of employees and returns a filtered list of employees with an even ID. 1: static List<Employee> GetEmployeesWithEvenID(List<Employee> employees) { 2: var filteredEmployees = new List<Employee>(); 3: foreach (Employee emp in employees) { 4: if (emp.ID % 2 == 0) { 5: filteredEmployees.Add(emp); 6: } 7: } 8: return filteredEmployees; 9: } The method can be rewritten to return an IEnumerable<Employee> using the yield return keyword. 1: static IEnumerable<Employee> GetEmployeesWithEvenID(IEnumerable<Employee> employees) { 2: foreach (Employee emp in employees) { 3: if (emp.ID % 2 == 0) { 4: yield return emp; 5: } 6: } 7: } We put these together in a console application. 1: using System; 2: using System.Collections.Generic; 3: //No System.Linq 4:  5: public class Program 6: { 7: [STAThread] 8: static void Main(string[] args) 9: { 10: var employees = new List<Employee> { 11: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 12: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 13: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 14: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" }, 15: }; 16: var filteredEmployees = GetEmployeesWithEvenID(employees); 17:  18: foreach (Employee emp in filteredEmployees) { 19: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 20: emp.ID, emp.FirstName, emp.LastName, emp.Country); 21: } 22:  23: Console.ReadLine(); 24: } 25: 26: static IEnumerable<Employee> GetEmployeesWithEvenID(IEnumerable<Employee> employees) { 27: foreach (Employee emp in employees) { 28: if (emp.ID % 2 == 0) { 29: yield return emp; 30: } 31: } 32: } 33: } 34:  35: public class Employee { 36: public int ID { get; set;} 37: public string FirstName { get; set;} 38: public string LastName {get; set;} 39: public string Country { get; set; } 40: } Output: ID 2 First_Name Jim Last_Name Ashlock Country UK ID 4 First_Name Jill Last_Name Anderson Country AUS Our filtering method is too specific. Let us change it so that it is capable of doing different types of filtering and lets give our method the name Where ;-) We will add another parameter to our Where method. This additional parameter will be a delegate with the following declaration. public delegate bool Filter(Employee emp); The idea is that the delegate parameter in our Where method will point to a method that contains the logic to do our filtering thereby freeing our Where method from any dependency. The method is shown below: 1: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 2: foreach (Employee emp in employees) { 3: if (filter(emp)) { 4: yield return emp; 5: } 6: } 7: } Making the change to our app, we create a new instance of the Filter delegate on line 14 with a target set to the method EmployeeHasEvenId. Running the code will produce the same output. 1: public delegate bool Filter(Employee emp); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: var employees = new List<Employee> { 9: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 10: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 11: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 12: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 13: }; 14: var filterDelegate = new Filter(EmployeeHasEvenId); 15: var filteredEmployees = Where(employees, filterDelegate); 16:  17: foreach (Employee emp in filteredEmployees) { 18: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 19: emp.ID, emp.FirstName, emp.LastName, emp.Country); 20: } 21: Console.ReadLine(); 22: } 23: 24: static bool EmployeeHasEvenId(Employee emp) { 25: return emp.ID % 2 == 0; 26: } 27: 28: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 29: foreach (Employee emp in employees) { 30: if (filter(emp)) { 31: yield return emp; 32: } 33: } 34: } 35: } 36:  37: public class Employee { 38: public int ID { get; set;} 39: public string FirstName { get; set;} 40: public string LastName {get; set;} 41: public string Country { get; set; } 42: } Lets use lambda expressions to inline the contents of the EmployeeHasEvenId method in place of the method. The next code snippet shows this change (see line 15).  For brevity, the Employee class declaration has been skipped. 1: public delegate bool Filter(Employee emp); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: var employees = new List<Employee> { 9: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 10: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 11: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 12: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 13: }; 14: var filterDelegate = new Filter(EmployeeHasEvenId); 15: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 16:  17: foreach (Employee emp in filteredEmployees) { 18: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 19: emp.ID, emp.FirstName, emp.LastName, emp.Country); 20: } 21: Console.ReadLine(); 22: } 23: 24: static bool EmployeeHasEvenId(Employee emp) { 25: return emp.ID % 2 == 0; 26: } 27: 28: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 29: foreach (Employee emp in employees) { 30: if (filter(emp)) { 31: yield return emp; 32: } 33: } 34: } 35: } 36:  The output displays the same two employees.  Our Where method is too restricted since it works with a collection of Employees only. Lets change it so that it works with any IEnumerable<T>. In addition, you may recall from my previous post,  that .NET 3.5 comes with a lot of predefined delegates including public delegate TResult Func<T, TResult>(T arg); We will get rid of our Filter delegate and use the one above instead. We apply these two changes to our code. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: var employees = new List<Employee> { 7: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 8: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 9: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 10: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 11: }; 12:  13: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 14:  15: foreach (Employee emp in filteredEmployees) { 16: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 17: emp.ID, emp.FirstName, emp.LastName, emp.Country); 18: } 19: Console.ReadLine(); 20: } 21: 22: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 23: foreach (var x in source) { 24: if (filter(x)) { 25: yield return x; 26: } 27: } 28: } 29: } We have successfully implemented a way to filter any IEnumerable<T> based on a  filter criteria. Projection Now lets enumerate on the items in the IEnumerable<Employee> we got from the Where method and copy them into a new IEnumerable<EmployeeFormatted>. The EmployeeFormatted class will only have a FullName and ID property. 1: public class EmployeeFormatted { 2: public int ID { get; set; } 3: public string FullName {get; set;} 4: } We could “project” our existing IEnumerable<Employee> into a new collection of IEnumerable<EmployeeFormatted> with the help of a new method. We will call this method Select ;-) 1: static IEnumerable<EmployeeFormatted> Select(IEnumerable<Employee> employees) { 2: foreach (var emp in employees) { 3: yield return new EmployeeFormatted { 4: ID = emp.ID, 5: FullName = emp.LastName + ", " + emp.FirstName 6: }; 7: } 8: } The changes are applied to our app. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: var employees = new List<Employee> { 7: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 8: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 9: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 10: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 11: }; 12:  13: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 14: var formattedEmployees = Select(filteredEmployees); 15:  16: foreach (EmployeeFormatted emp in formattedEmployees) { 17: Console.WriteLine("ID {0} Full_Name {1}", 18: emp.ID, emp.FullName); 19: } 20: Console.ReadLine(); 21: } 22:  23: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 24: foreach (var x in source) { 25: if (filter(x)) { 26: yield return x; 27: } 28: } 29: } 30: 31: static IEnumerable<EmployeeFormatted> Select(IEnumerable<Employee> employees) { 32: foreach (var emp in employees) { 33: yield return new EmployeeFormatted { 34: ID = emp.ID, 35: FullName = emp.LastName + ", " + emp.FirstName 36: }; 37: } 38: } 39: } 40:  41: public class Employee { 42: public int ID { get; set;} 43: public string FirstName { get; set;} 44: public string LastName {get; set;} 45: public string Country { get; set; } 46: } 47:  48: public class EmployeeFormatted { 49: public int ID { get; set; } 50: public string FullName {get; set;} 51: } Output: ID 2 Full_Name Ashlock, Jim ID 4 Full_Name Anderson, Jill We have successfully selected employees who have an even ID and then shaped our data with the help of the Select method so that the final result is an IEnumerable<EmployeeFormatted>.  Lets make our Select method more generic so that the user is given the freedom to shape what the output would look like. We can do this, like before, with lambda expressions. Our Select method is changed to accept a delegate as shown below. TSource will be the type of data that comes in and TResult will be the type the user chooses (shape of data) as returned from the selector delegate. 1:  2: static IEnumerable<TResult> Select<TSource, TResult>(IEnumerable<TSource> source, Func<TSource, TResult> selector) { 3: foreach (var x in source) { 4: yield return selector(x); 5: } 6: } We see the new changes to our app. On line 15, we use lambda expression to specify the shape of the data. In this case the shape will be of type EmployeeFormatted. 1:  2: public class Program 3: { 4: [STAThread] 5: static void Main(string[] args) 6: { 7: var employees = new List<Employee> { 8: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 9: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 10: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 11: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 12: }; 13:  14: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 15: var formattedEmployees = Select(filteredEmployees, (emp) => 16: new EmployeeFormatted { 17: ID = emp.ID, 18: FullName = emp.LastName + ", " + emp.FirstName 19: }); 20:  21: foreach (EmployeeFormatted emp in formattedEmployees) { 22: Console.WriteLine("ID {0} Full_Name {1}", 23: emp.ID, emp.FullName); 24: } 25: Console.ReadLine(); 26: } 27: 28: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 29: foreach (var x in source) { 30: if (filter(x)) { 31: yield return x; 32: } 33: } 34: } 35: 36: static IEnumerable<TResult> Select<TSource, TResult>(IEnumerable<TSource> source, Func<TSource, TResult> selector) { 37: foreach (var x in source) { 38: yield return selector(x); 39: } 40: } 41: } The code outputs the same result as before. On line 14 we filter our data and on line 15 we project our data. What if we wanted to be more expressive and concise? We could combine both line 14 and 15 into one line as shown below. Assuming you had to perform several operations like this on our collection, you would end up with some very unreadable code! 1: var formattedEmployees = Select(Where(employees, emp => emp.ID % 2 == 0), (emp) => 2: new EmployeeFormatted { 3: ID = emp.ID, 4: FullName = emp.LastName + ", " + emp.FirstName 5: }); A cleaner way to write this would be to give the appearance that the Select and Where methods were part of the IEnumerable<T>. This is exactly what extension methods give us. Extension methods have to be defined in a static class. Let us make the Select and Where extension methods on IEnumerable<T> 1: public static class MyExtensionMethods { 2: static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 3: foreach (var x in source) { 4: if (filter(x)) { 5: yield return x; 6: } 7: } 8: } 9: 10: static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 11: foreach (var x in source) { 12: yield return selector(x); 13: } 14: } 15: } The creation of the extension method makes the syntax much cleaner as shown below. We can write as many extension methods as we want and keep on chaining them using this technique. 1: var formattedEmployees = employees 2: .Where(emp => emp.ID % 2 == 0) 3: .Select (emp => new EmployeeFormatted { ID = emp.ID, FullName = emp.LastName + ", " + emp.FirstName }); Making these changes and running our code produces the same result. 1: using System; 2: using System.Collections.Generic; 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: var employees = new List<Employee> { 10: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 11: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 12: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 13: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 14: }; 15:  16: var formattedEmployees = employees 17: .Where(emp => emp.ID % 2 == 0) 18: .Select (emp => 19: new EmployeeFormatted { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: } 23: ); 24:  25: foreach (EmployeeFormatted emp in formattedEmployees) { 26: Console.WriteLine("ID {0} Full_Name {1}", 27: emp.ID, emp.FullName); 28: } 29: Console.ReadLine(); 30: } 31: } 32:  33: public static class MyExtensionMethods { 34: static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 35: foreach (var x in source) { 36: if (filter(x)) { 37: yield return x; 38: } 39: } 40: } 41: 42: static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 43: foreach (var x in source) { 44: yield return selector(x); 45: } 46: } 47: } 48:  49: public class Employee { 50: public int ID { get; set;} 51: public string FirstName { get; set;} 52: public string LastName {get; set;} 53: public string Country { get; set; } 54: } 55:  56: public class EmployeeFormatted { 57: public int ID { get; set; } 58: public string FullName {get; set;} 59: } Let’s change our code to return a collection of anonymous types and get rid of the EmployeeFormatted type. We see that the code produces the same output. 1: using System; 2: using System.Collections.Generic; 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: var employees = new List<Employee> { 10: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 11: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 12: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 13: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 14: }; 15:  16: var formattedEmployees = employees 17: .Where(emp => emp.ID % 2 == 0) 18: .Select (emp => 19: new { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: } 23: ); 24:  25: foreach (var emp in formattedEmployees) { 26: Console.WriteLine("ID {0} Full_Name {1}", 27: emp.ID, emp.FullName); 28: } 29: Console.ReadLine(); 30: } 31: } 32:  33: public static class MyExtensionMethods { 34: public static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 35: foreach (var x in source) { 36: if (filter(x)) { 37: yield return x; 38: } 39: } 40: } 41: 42: public static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 43: foreach (var x in source) { 44: yield return selector(x); 45: } 46: } 47: } 48:  49: public class Employee { 50: public int ID { get; set;} 51: public string FirstName { get; set;} 52: public string LastName {get; set;} 53: public string Country { get; set; } 54: } To be more expressive, C# allows us to write our extension method calls as a query expression. Line 16 can be rewritten a query expression like so: 1: var formattedEmployees = from emp in employees 2: where emp.ID % 2 == 0 3: select new { 4: ID = emp.ID, 5: FullName = emp.LastName + ", " + emp.FirstName 6: }; When the compiler encounters an expression like the above, it simply rewrites it as calls to our extension methods.  So far we have been using our extension methods. The System.Linq namespace contains several extension methods for objects that implement the IEnumerable<T>. You can see a listing of these methods in the Enumerable class in the System.Linq namespace. Let’s get rid of our extension methods (which I purposefully wrote to be of the same signature as the ones in the Enumerable class) and use the ones provided in the Enumerable class. Our final code is shown below: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; //Added 4:  5: public class Program 6: { 7: [STAThread] 8: static void Main(string[] args) 9: { 10: var employees = new List<Employee> { 11: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 12: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 13: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 14: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 15: }; 16:  17: var formattedEmployees = from emp in employees 18: where emp.ID % 2 == 0 19: select new { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: }; 23:  24: foreach (var emp in formattedEmployees) { 25: Console.WriteLine("ID {0} Full_Name {1}", 26: emp.ID, emp.FullName); 27: } 28: Console.ReadLine(); 29: } 30: } 31:  32: public class Employee { 33: public int ID { get; set;} 34: public string FirstName { get; set;} 35: public string LastName {get; set;} 36: public string Country { get; set; } 37: } 38:  39: public class EmployeeFormatted { 40: public int ID { get; set; } 41: public string FullName {get; set;} 42: } This post has shown you a basic overview of LINQ to Objects work by showning you how an expression is converted to a sequence of calls to extension methods when working directly with objects. It gets more interesting when working with LINQ to SQL where an expression tree is constructed – an in memory data representation of the expression. The C# compiler compiles these expressions into code that builds an expression tree at runtime. The provider can then traverse the expression tree and generate the appropriate SQL query. You can read more about expression trees in this MSDN article.

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• "domain crashed" when creating new Xen instance

  - by user47650

  I have downloaded a Xen virtual machine image from the appscale project, and I am trying to start it up. However once I run the command; xm create -c -f xen.conf The instance immediately crashes and provides no console output. however it produces logs that I have posted below. but this is the error; [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. I have managed to mount the root.img file locally and verify that it is actually an ext3 file system. I am running Xen 3.0.3 that is a stock RPM from the CentOS 5 repos; # rpm -qa | grep -i xen xen-libs-3.0.3-105.el5_5.5 xen-3.0.3-105.el5_5.5 xen-libs-3.0.3-105.el5_5.5 kernel-xen-2.6.18-194.32.1.el5 any suggestions on how to proceed with troubleshooting? (i am a newbie to Xen) so far I have enabled console logging, but the log file is empty. ==> domain-builder-ng.log <== xc_dom_allocate: cmdline=" ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console", features="" xc_dom_kernel_file: filename="/boot/vmlinuz-2.6.27-7-server" xc_dom_malloc_filemap : 2284 kB xc_dom_ramdisk_file: filename="/boot/initrd.img-2.6.27-7-server" xc_dom_malloc_filemap : 9005 kB xc_dom_boot_xen_init: ver 3.1, caps xen-3.0-x86_64 xen-3.0-x86_32p xc_dom_parse_image: called xc_dom_find_loader: trying ELF-generic loader ... failed xc_dom_find_loader: trying Linux bzImage loader ... xc_dom_malloc : 9875 kB xc_dom_do_gunzip: unzip ok, 0x234bb2 -> 0x9a4de0 OK elf_parse_binary: phdr: paddr=0x200000 memsz=0x447000 elf_parse_binary: phdr: paddr=0x647000 memsz=0xab888 elf_parse_binary: phdr: paddr=0x6f3000 memsz=0x908 elf_parse_binary: phdr: paddr=0x6f4000 memsz=0x1c2f9c elf_parse_binary: memory: 0x200000 -> 0x8b6f9c elf_xen_parse_note: GUEST_OS = "linux" elf_xen_parse_note: GUEST_VERSION = "2.6" elf_xen_parse_note: XEN_VERSION = "xen-3.0" elf_xen_parse_note: VIRT_BASE = 0xffffffff80000000 elf_xen_parse_note: ENTRY = 0xffffffff8071e200 elf_xen_parse_note: HYPERCALL_PAGE = 0xffffffff80209000 elf_xen_parse_note: FEATURES = "!writable_page_tables|pae_pgdir_above_4gb" elf_xen_parse_note: PAE_MODE = "yes" elf_xen_parse_note: LOADER = "generic" elf_xen_parse_note: unknown xen elf note (0xd) elf_xen_parse_note: SUSPEND_CANCEL = 0x1 elf_xen_parse_note: HV_START_LOW = 0xffff800000000000 elf_xen_parse_note: PADDR_OFFSET = 0x0 elf_xen_addr_calc_check: addresses: virt_base = 0xffffffff80000000 elf_paddr_offset = 0x0 virt_offset = 0xffffffff80000000 virt_kstart = 0xffffffff80200000 virt_kend = 0xffffffff808b6f9c virt_entry = 0xffffffff8071e200 xc_dom_parse_elf_kernel: xen-3.0-x86_64: 0xffffffff80200000 -> 0xffffffff808b6f9c xc_dom_mem_init: mem 1024 MB, pages 0x40000 pages, 4k each xc_dom_mem_init: 0x40000 pages xc_dom_boot_mem_init: called x86_compat: guest xen-3.0-x86_64, address size 64 xc_dom_malloc : 2048 kB ==> xend.log <== [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 9 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:207) XendDomainInfo.create(['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]]) [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:329) parseConfig: config is ['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]] [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:446) parseConfig: result is {'features': '', 'image': ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']], 'cpus': [], 'vcpu_avail': 1, 'backend': [], 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'cpu_weight': 256.0, 'memory': 1024, 'cpu_cap': 0, 'localtime': None, 'timer_mode': None, 'start_time': 1299011639.9200001, 'on_poweroff': 'destroy', 'on_crash': 'restart', 'device': [('vif', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]), ('vbd', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']])], 'bootloader': None, 'maxmem': 1024, 'shadow_memory': 0, 'name': 'appscale-1.4b', 'bootloader_args': None, 'vcpus': 1, 'cpu': None} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1784) XendDomainInfo.construct: None [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034420 KiB free; need 4096; done. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1953) XendDomainInfo.initDomain: 10 256.0 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1994) _initDomain:shadow_memory=0x0, maxmem=0x400, memory=0x400. [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034412 KiB free; need 1048576; done. [2011-03-01 12:34:02 xend 3580] INFO (image:139) buildDomain os=linux dom=10 vcpus=1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:208) domid = 10 [2011-03-01 12:34:02 xend 3580] DEBUG (image:209) memsize = 1024 [2011-03-01 12:34:02 xend 3580] DEBUG (image:210) image = /boot/vmlinuz-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:211) store_evtchn = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:212) console_evtchn = 2 [2011-03-01 12:34:02 xend 3580] DEBUG (image:213) cmdline = ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console [2011-03-01 12:34:02 xend 3580] DEBUG (image:214) ramdisk = /boot/initrd.img-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:215) vcpus = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:216) features = ==> domain-builder-ng.log <== xc_dom_build_image: called xc_dom_alloc_segment: kernel : 0xffffffff80200000 -> 0xffffffff808b7000 (pfn 0x200 + 0x6b7 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x200+0x6b7 at 0x2aaaab5f6000 elf_load_binary: phdr 0 at 0x0x2aaaab5f6000 -> 0x0x2aaaaba3d000 elf_load_binary: phdr 1 at 0x0x2aaaaba3d000 -> 0x0x2aaaabae8888 elf_load_binary: phdr 2 at 0x0x2aaaabae9000 -> 0x0x2aaaabae9908 elf_load_binary: phdr 3 at 0x0x2aaaabaea000 -> 0x0x2aaaabb9a004 xc_dom_alloc_segment: ramdisk : 0xffffffff808b7000 -> 0xffffffff82382000 (pfn 0x8b7 + 0x1acb pages) xc_dom_malloc : 160 kB xc_dom_pfn_to_ptr: domU mapping: pfn 0x8b7+0x1acb at 0x2aaab0000000 xc_dom_do_gunzip: unzip ok, 0x8cb5e7 -> 0x1aca210 xc_dom_alloc_segment: phys2mach : 0xffffffff82382000 -> 0xffffffff82582000 (pfn 0x2382 + 0x200 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2382+0x200 at 0x2aaab1acb000 xc_dom_alloc_page : start info : 0xffffffff82582000 (pfn 0x2582) xc_dom_alloc_page : xenstore : 0xffffffff82583000 (pfn 0x2583) xc_dom_alloc_page : console : 0xffffffff82584000 (pfn 0x2584) nr_page_tables: 0x0000ffffffffffff/48: 0xffff000000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x0000007fffffffff/39: 0xffffff8000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x000000003fffffff/30: 0xffffffff80000000 -> 0xffffffffbfffffff, 1 table(s) nr_page_tables: 0x00000000001fffff/21: 0xffffffff80000000 -> 0xffffffff827fffff, 20 table(s) xc_dom_alloc_segment: page tables : 0xffffffff82585000 -> 0xffffffff8259c000 (pfn 0x2585 + 0x17 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2585+0x17 at 0x2aaab1ccb000 xc_dom_alloc_page : boot stack : 0xffffffff8259c000 (pfn 0x259c) xc_dom_build_image : virt_alloc_end : 0xffffffff8259d000 xc_dom_build_image : virt_pgtab_end : 0xffffffff82800000 xc_dom_boot_image: called arch_setup_bootearly: doing nothing xc_dom_compat_check: supported guest type: xen-3.0-x86_64 <= matches xc_dom_compat_check: supported guest type: xen-3.0-x86_32p xc_dom_update_guest_p2m: dst 64bit, pages 0x40000 clear_page: pfn 0x2584, mfn 0x11d788 clear_page: pfn 0x2583, mfn 0x11d789 xc_dom_pfn_to_ptr: domU mapping: pfn 0x2582+0x1 at 0x2aaab1ce2000 start_info_x86_64: called setup_hypercall_page: vaddr=0xffffffff80209000 pfn=0x209 domain builder memory footprint allocated malloc : 12139 kB anon mmap : 0 bytes mapped file mmap : 11289 kB domU mmap : 35 MB arch_setup_bootlate: shared_info: pfn 0x0, mfn 0xd6fe1 shared_info_x86_64: called vcpu_x86_64: called vcpu_x86_64: cr3: pfn 0x2585 mfn 0x11d787 launch_vm: called, ctxt=0x97b21f8 xc_dom_release: called ==> xend.log <== [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'mac': '00:16:3B:72:10:E4', 'handle': '0', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vif/10/0'} to /local/domain/10/device/vif/0. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'handle': '0', 'script': '/etc/xen/scripts/vif-bridge', 'state': '1', 'frontend': '/local/domain/10/device/vif/0', 'mac': '00:16:3B:72:10:E4', 'online': '1', 'frontend-id': '10'} to /local/domain/0/backend/vif/10/0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:634) Checking for duplicate for uname: /local/xen/domains/appscale1.4/root.img [file:/local/xen/domains/appscale1.4/root.img], dev: sda1:disk, mode: w [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1:disk: [Errno 2] No such file or directory: '/dev/sda1:disk' [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1: [Errno 2] No such file or directory: '/dev/sda1' [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'virtual-device': '2049', 'device-type': 'disk', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vbd/10/2049'} to /local/domain/10/device/vbd/2049. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'frontend': '/local/domain/10/device/vbd/2049', 'format': 'raw', 'dev': 'sda1', 'state': '1', 'params': '/local/xen/domains/appscale1.4/root.img', 'mode': 'w', 'online': '1', 'frontend-id': '10', 'type': 'file'} to /local/domain/0/backend/vbd/10/2049. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:993) Storing VM details: {'shadow_memory': '0', 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'start_time': '1299011642.74', 'on_poweroff': 'destroy', 'name': 'appscale-1.4b', 'xend/restart_count': '0', 'vcpus': '1', 'vcpu_avail': '1', 'memory': '1024', 'on_crash': 'restart', 'image': "(linux (kernel /boot/vmlinuz-2.6.27-7-server) (ramdisk /boot/initrd.img-2.6.27-7-server) (ip :1.2.3.4::::eth0:dhcp) (root '/dev/sda1 ro') (args 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'))", 'maxmem': '1024'} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1028) Storing domain details: {'console/ring-ref': '1169288', 'console/port': '2', 'name': 'appscale-1.4b', 'console/limit': '1048576', 'vm': '/vm/d5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'domid': '10', 'cpu/0/availability': 'online', 'memory/target': '1048576', 'store/ring-ref': '1169289', 'store/port': '1'} [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:158) Waiting for devices vif. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:164) Waiting for 0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1250) XendDomainInfo.handleShutdownWatch [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices usb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:164) Waiting for 2049. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices irq. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vkbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vfb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices pci. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices ioports. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices tap. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vtpm. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] ERROR (XendDomainInfo:2654) VM appscale-1.4b restarting too fast (2.275545 seconds since the last restart). Refusing to restart to avoid loops. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2189) XendDomainInfo.destroy: domid=10 ==> xen-hotplug.log <== Nothing to flush. ==> xend.log <== [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 10 [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... And this is the xen.conf file that I am using; # cat xen.conf # Configuration file for the Xen instance AppScale, created # bn VMBuilder kernel = '/boot/vmlinuz-2.6.27-7-server' ramdisk = '/boot/initrd.img-2.6.27-7-server' memory = 1024 vcpus = 1 root = '/dev/sda1 ro' disk = [ 'file:/local/xen/domains/appscale1.4/root.img,sda1,w', ] name = 'appscale-1.4b' dhcp = 'dhcp' vif = [ 'mac=00:16:3B:72:10:E4' ] on_poweroff = 'destroy' on_reboot = 'restart' on_crash = 'restart' extra = 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'

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• Minecraft Style Chunk building problem

  - by David Torrey

  I'm having some problems with speed in my chunk engine. I timed it out, and in its current state it takes a total ~5 seconds per chunk to fill each face's list. I have a check to see if each face of a block is visible and if it is not visible, it skips it and moves on. I'm using a dictionary (unordered map) because it makes sense memorywise to just not have an entry if there is no block. I've tracked my problem down to testing if there is an entry, and accessing an entry if it does exist. If I remove the tests to see if there is an entry in the dictionary for an adjacent block, or if the block type itself is seethrough, it runs within about 2-4 milliseconds. so here's my question: Is there a faster way to check for an entry in a dictionary than .ContainsKey()? As an aside, I tried TryGetValue() and it doesn't really help with the speed that much. If I remove the ContainsKey() and keep the test where it does the IsSeeThrough for each block, it halves the time, but it's still about 2-3 seconds. It only drops to 2-4ms if I remove BOTH checks. Here is my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Runtime.InteropServices; using OpenTK; using OpenTK.Graphics.OpenGL; using System.Drawing; namespace Anabelle_Lee { public enum BlockEnum { air = 0, dirt = 1, } [StructLayout(LayoutKind.Sequential,Pack=1)] public struct Coordinates<T1> { public T1 x; public T1 y; public T1 z; public override string ToString() { return "(" + x + "," + y + "," + z + ") : " + typeof(T1); } } public struct Sides<T1> { public T1 left; public T1 right; public T1 top; public T1 bottom; public T1 front; public T1 back; } public class Block { public int blockType; public bool SeeThrough() { switch (blockType) { case 0: return true; } return false ; } public override string ToString() { return ((BlockEnum)(blockType)).ToString(); } } class Chunk { private Dictionary<Coordinates<byte>, Block> mChunkData; //stores the block data private Sides<List<Coordinates<byte>>> mVBOVertexBuffer; private Sides<int> mVBOHandle; //private bool mIsChanged; private const byte mCHUNKSIZE = 16; public Chunk() { } public void InitializeChunk() { //create VBO references #if DEBUG Console.WriteLine ("Initializing Chunk"); #endif mChunkData = new Dictionary<Coordinates<byte> , Block>(); //mIsChanged = true; GL.GenBuffers(1, out mVBOHandle.left); GL.GenBuffers(1, out mVBOHandle.right); GL.GenBuffers(1, out mVBOHandle.top); GL.GenBuffers(1, out mVBOHandle.bottom); GL.GenBuffers(1, out mVBOHandle.front); GL.GenBuffers(1, out mVBOHandle.back); //make new list of vertexes for each face mVBOVertexBuffer.top = new List<Coordinates<byte>>(); mVBOVertexBuffer.bottom = new List<Coordinates<byte>>(); mVBOVertexBuffer.left = new List<Coordinates<byte>>(); mVBOVertexBuffer.right = new List<Coordinates<byte>>(); mVBOVertexBuffer.front = new List<Coordinates<byte>>(); mVBOVertexBuffer.back = new List<Coordinates<byte>>(); #if DEBUG Console.WriteLine("Chunk Initialized"); #endif } public void GenerateChunk() { #if DEBUG Console.WriteLine("Generating Chunk"); #endif for (byte i = 0; i < mCHUNKSIZE; i++) { for (byte j = 0; j < mCHUNKSIZE; j++) { for (byte k = 0; k < mCHUNKSIZE; k++) { Random blockLoc = new Random(); Coordinates<byte> randChunk = new Coordinates<byte> { x = i, y = j, z = k }; mChunkData.Add(randChunk, new Block()); mChunkData[randChunk].blockType = blockLoc.Next(0, 1); } } } #if DEBUG Console.WriteLine("Chunk Generated"); #endif } public void DeleteChunk() { //delete VBO references #if DEBUG Console.WriteLine("Deleting Chunk"); #endif GL.DeleteBuffers(1, ref mVBOHandle.left); GL.DeleteBuffers(1, ref mVBOHandle.right); GL.DeleteBuffers(1, ref mVBOHandle.top); GL.DeleteBuffers(1, ref mVBOHandle.bottom); GL.DeleteBuffers(1, ref mVBOHandle.front); GL.DeleteBuffers(1, ref mVBOHandle.back); //clear all vertex buffers ClearPolyLists(); #if DEBUG Console.WriteLine("Chunk Deleted"); #endif } public void UpdateChunk() { #if DEBUG Console.WriteLine("Updating Chunk"); #endif ClearPolyLists(); //prepare buffers //for every entry in mChunkData map foreach(KeyValuePair<Coordinates<byte>,Block> feBlockData in mChunkData) { Coordinates<byte> checkBlock = new Coordinates<byte> { x = feBlockData.Key.x, y = feBlockData.Key.y, z = feBlockData.Key.z }; //check for polygonson the left side of the cube if (checkBlock.x > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x - 1, checkBlock.y, checkBlock.z)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.left); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.left); } //check for polygons on the right side of the cube if (checkBlock.x < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x + 1, checkBlock.y, checkBlock.z)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.right); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.right); } if (checkBlock.y > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x, checkBlock.y - 1, checkBlock.z)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.bottom); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.bottom); } //check for polygons on the right side of the cube if (checkBlock.y < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x, checkBlock.y + 1, checkBlock.z)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.top); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.top); } if (checkBlock.z > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x, checkBlock.y, checkBlock.z - 1)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.back); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.back); } //check for polygons on the right side of the cube if (checkBlock.z < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x, checkBlock.y, checkBlock.z + 1)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.front); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.front); } } BuildBuffers(); #if DEBUG Console.WriteLine("Chunk Updated"); #endif } public void RenderChunk() { } public void LoadChunk() { #if DEBUG Console.WriteLine("Loading Chunk"); #endif #if DEBUG Console.WriteLine("Chunk Deleted"); #endif } public void SaveChunk() { #if DEBUG Console.WriteLine("Saving Chunk"); #endif #if DEBUG Console.WriteLine("Chunk Saved"); #endif } private bool IsVisible(int pX,int pY,int pZ) { Block testBlock; Coordinates<byte> checkBlock = new Coordinates<byte> { x = Convert.ToByte(pX), y = Convert.ToByte(pY), z = Convert.ToByte(pZ) }; if (mChunkData.TryGetValue(checkBlock,out testBlock )) //if data exists { if (testBlock.SeeThrough() == true) //if existing data is not seethrough { return true; } } return true; } private void AddPoly(byte pX, byte pY, byte pZ, int BufferSide) { //create temp array GL.BindBuffer(BufferTarget.ArrayBuffer, BufferSide); if (BufferSide == mVBOHandle.front) { //front face mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); } else if (BufferSide == mVBOHandle.right) { //back face mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.top) { //left face mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.bottom) { //right face mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); } else if (BufferSide == mVBOHandle.front) { //top face mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.back) { //bottom face mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ + 1) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ + 1) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ + 1) }); } } private void BuildBuffers() { #if DEBUG Console.WriteLine("Building Chunk Buffers"); #endif GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.front); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.front.Count), mVBOVertexBuffer.front.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.back); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.back.Count), mVBOVertexBuffer.back.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.left); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.left.Count), mVBOVertexBuffer.left.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.right); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.right.Count), mVBOVertexBuffer.right.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.top); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.top.Count), mVBOVertexBuffer.top.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.bottom); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.bottom.Count), mVBOVertexBuffer.bottom.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer,0); #if DEBUG Console.WriteLine("Chunk Buffers Built"); #endif } private void ClearPolyLists() { #if DEBUG Console.WriteLine("Clearing Polygon Lists"); #endif mVBOVertexBuffer.top.Clear(); mVBOVertexBuffer.bottom.Clear(); mVBOVertexBuffer.left.Clear(); mVBOVertexBuffer.right.Clear(); mVBOVertexBuffer.front.Clear(); mVBOVertexBuffer.back.Clear(); #if DEBUG Console.WriteLine("Polygon Lists Cleared"); #endif } }//END CLASS }//END NAMESPACE

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• How do I change the color settings in emacs23 running in a terminal console?

  - by Anonymous

  I use xterm and set its appearance in ~/.Xdefaults: XTerm*background: paleTurquoise XTerm*foreground: black I also use emacs, but set its appearance differently in ~/.emacs: (set-background-color "black") (set-foreground-color "yellow") I usually run emacs within the terminal console with emacs -nw, rather than creating a separate X window. For some reason, this doesn't work properly for emacs23; instead, emacs retains the pale turquoise background of my xterm window. Looking at what's new in emacs23, I noted that: ** When running in a new enough xterm (newer than version 242), Emacs asks xterm what the background color is and it sets up faces accordingly for a dark background if needed (the current default is to consider the background light). So it's a feature, not a bug? Anyway, is there some way that I can I tell emacs23 to ignore the xterm background settings when running in console mode, and use the settings in ~/.emacs instead? I'll also note that: Running M-x set-background-color within emacs23 -nw has no effect. It works fine in emacs23 running in a separate X window (without the -nw option). It worked fine in emacs22; and I'm not really sure whether I need to use emacs23... It's not just xterm: the same problem exists with $TERM=cygwin, for example.

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• Cross compiling from MinGW on Fedora 12 to Windows - console window?

  - by elcuco

  After reading this article http://lukast.mediablog.sk/log/?p=155 I decided to use mingw on linux to compile windows applications. This means I can compile, test, debug and release directly from Linux. I hacked this build script which will cross compile the application and even package it in a ZIP file. Note that I am using out of source builds for QMake (did you even know this is supported? wow...). Also note that the script will pull the needed DLLs automagically. Here is the script for you all internets to use and abuse: #! /bin/sh set -x set -e VERSION=0.1 PRO_FILE=blabla.pro BUILD_DIR=mingw_build DIST_DIR=blabla-$VERSION-win32 # clean up old shite rm -fr $BUILD_DIR mkdir $BUILD_DIR cd $BUILD_DIR # start building QMAKESPEC=fedora-win32-cross qmake-qt4 QT_LIBINFIX=4 config=\"release\ quiet\" ../$PRO_FILE #qmake-qt4 -spec fedora-win32-cross make DLLS=`i686-pc-mingw32-objdump -p release/*.exe | grep dll | awk '{print $3}'` for i in $DLLS mingwm10.dll ; do f=/usr/i686-pc-mingw32/sys-root/mingw/bin/$i if [ ! -f $f ]; then continue; fi cp -av $f release done mkdir -p $DIST_DIR mv release/*.exe $DIST_DIR mv release/*.dll $DIST_DIR zip -r ../$DIST_DIR.zip $DIST_DIR The compiled binary works on the Windows7 machine I tested. Now to the questions: When I execute the application on Windows, the theme is not the Windows7 theme. I assume I am missing a style module, I am not really sure yet. The application gets a console window for some reason. The second point (the console window) is critical. How can I remove this background window? Please note that the extra config lines are not working for me, what am I missing there?

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• jQuery code works for console but not in-page.

  - by justSteve

  I have a form element defined as: <div class="field"> <div class="name"> <label for="User_LastName"> Last name: <span class="asterisk">*</span></label> </div> <div class="value"> <%= Html.TextBox("User.LastName", Model.LastName)%> <%= Html.ValidationMessage("User.LastName")%> </div> </div> and a jQuery selector that is supposed to detect when the input gets focus and highlight the parent: $("input").focus(function() { //watching for an event where an input form comes into focus $(this) .parent() .addClass("curFocus") .children("div") .toggle(); }); If i paste this code into firebug's console - things work as planned. However, i'm running this from a 'RenderPartial' .net mvc page. Other jQuery code sitting within the same $(document).ready(function() { block work correctly. The form uses html helpers to generate the inputs which might complicate the process somewhat - but even so... i'm seeing correct behavior when that code's in console but not in a 'real-time' page. How do i troubleshoot this?

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• Need help: input int from console and pass it into method in different class and do math

  - by christophe

  i'm a beginner, Need help, Please!!! I want to read optional number "a" from console and then store it in variable to use as passing to a different class (different .java file). and pint the sum separetely by optional inputting. How do i code the 2 classes? thanks /* * DemoApp.java */ public class DemoApp { public static void main(String[] args) { Scanner input = new Scanner(System.in); int a; System.out.println("Input one of the following 3 numbers: 100, 200, 300"); System.out.print("Enter: "); a = input.nextInt(); TestApplication testapp = new TestApplication(); testapp.test(a); } } /* * TestApplication.java * */ public class TestApplication { private int a; public void test(int a) { this.a = a; // TODO: where to get the "a"? (entered by users from console) System.out.println("The number_a was passed in: "+a); } protected void printNum() throws Exception { int num; switch (a) { case 100: num = num + 10; break; case 200: num = num + 20; break; case 300: num = num + 30; break; default: // TODO: unexpected number input. throw(); break; } System.out.println("I got a sum number"+num); } }

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• New Features and Changes in OIM11gR2

  - by Abhishek Tripathi

  WEB CONSOLEs in OIM 11gR2 ** In 11gR1 there were 3 Admin Web Consoles : ·         Self Service Console ·         Administration Console and ·         Advanced Administration Console accessible Whereas in OIM 11gR2 , Self Service and Administration Console have are now combined and now called as Identity Self Service Console http://host:port/identity  This console has 3 features in it for managing self profile (My Profile), Managing Requests like requesting for App Instances and Approving requests (Requests) and General Administration tasks of creating/managing users, roles, organization, attestation etc (Administration) ** In OIM 11gR2 – new console sysadmin has been added Administrators which includes some of the design console functions apart from general administrations features. http://host:port/sysadmin   Application Instances Application instance is the object that is to be provisioned to a user. Application Instances are checked out in the catalog and user can request for application instances via catalog. ·         In OIM 11gR2 resources and entitlements are bundled in Application Instance which user can select and request from catalog.  ·         Application instance is a combination of IT Resource and RO. So, you cannot create another App Instance with the same RO & IT Resource if it already exists for some other App Instance. One of these ( RO or IT Resource) must have a different name. ·         If you want that users of a particular Organization should be able to request for an Application instances through catalog then App Instances must be attached to that particular Organization. ·         Application instance can be associated with multiple organizations. ·         An application instance can also have entitlements associated with it. Entitlement can include Roles/Groups or Responsibility. ·         Application Instance are published to the catalog by a scheduled task “Catalog Synchronization Job” ·         Application Instance can have child/ parent application instance where child application instance inherits all attributes of parent application instance. Important point to remember with Application Instance If you delete the application Instance in OIM 11gR2 and create a new one with the same name, OIM will not allow doing so. It throws error saying Application Instance already exists with same Resource Object and IT resource. This is because there is still some reference that is not removed in OIM for deleted application Instance.  So to completely delete your application Instance from OIM, you must: 1. Delete the app Instance from sysadmin console. 2. Run the App Instance Post Delete Processing Job in Revoke/Delete mode. 3. Run the Catalog Synchronization job. Once done, you should be able to create a new App instance with the previous RO & IT Resouce name.   Catalog  Catalog allows users to request Roles, Application Instance, and Entitlements in an Application. Catalog Items – Roles, Application Instance and Entitlements that can be requested via catalog are called as catalog items. Detailed Information ( attributes of Catalog item)  Category – Each catalog item is associated with one and only one category. Catalog Administrators can provide a value for catalog item. ·         Tags – are search keywords helpful in searching Catalog. When users search the Catalog, the search is performed against the tags. To define a tag, go to Catalog->Search the resource-> select the resource-> update the tag field with custom search keyword. Tags are of three types: a) Auto-generated Tags: The Catalog synchronization process auto-tags the Catalog Item using the Item Type, Item Name and Item Display Name b) User-defined Tags: User-defined Tags are additional keywords entered by the Catalog Administrator. c) Arbitrary Tags: While defining a metadata if user has marked that metadata as searchable, then that will also be part of tags.   Sandbox  Sanbox is a new feature introduced in OIM11gR2. This serves as a temporary development environment for UI customizations so that they don’t affect other users before they are published and linked to existing OIM UI. All UI customizations should be done inside a sandbox, this ensures that your changes/modifications don’t affect other users until you have finalized the changes and customization is complete. Once UI customization is completed, the Sandbox must be published for the customizations to be merged into existing UI and available to other users. Creating and activating a sandbox is mandatory for customizing the UI by .Without an active sandbox, OIM does not allow to customize any page. a)      Before you perform any activity in OIM (like Create/Modify Forms, Custom Attribute, creating application instances, adding roles/attributes to catalog) you must create a Sand Box and activate it. b)      One can create multiple sandboxes in OIM but only one sandbox can be active at any given time. c)      You can export/import the sandbox to move the changes from one environment to the other. Creating Sandbox To create sandbox, login to identity manager self service (/identity) or System Administration (/sysadmin) and click on top right of link “Sandboxes” and then click on Create SandBox. Publishing Sandbox Before you publish a sandbox, it is recommended to backup MDS. Use /EM to backup MDS by following the steps below : Creating MDS Backup 1.      Login to Oracle Enterprise Manager as the administrator. 2.      On the landing page, click oracle.iam.console.identity.self-service.ear(V2.0). 3.      From the Application Deployment menu at the top, select MDS configuration. 4.      Under Export, select the Export metadata documents to an archive on the machine where this web browser is running option, and then click Export. All the metadata is exported in a ZIP file.   Creating Password Policy through Admin Console : In 11gR1 and previous versions password policies could be created & applied via OIM Design Console only. From OIM11gR2 onwards, Password Policies can be created and assigned using Admin Console as well.  

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• JavaScript: this

  - by bdukes

  JavaScript is a language steeped in juxtaposition.  It was made to “look like Java,” yet is dynamic and classless.  From this origin, we get the new operator and the this keyword.  You are probably used to this referring to the current instance of a class, so what could it mean in a language without classes? In JavaScript, this refers to the object off of which a function is referenced when it is invoked (unless it is invoked via call or apply). What this means is that this is not bound to your function, and can change depending on how your function is invoked. It also means that this changes when declaring a function inside another function (i.e. each function has its own this), such as when writing a callback. Let's see some of this in action: var obj = { count: 0, increment: function () { this.count += 1; }, logAfterTimeout = function () { setTimeout(function () { console.log(this.count); }, 1); } }; obj.increment(); console.log(obj.count); // 1 var increment = obj.increment; window.count = 'global count value: '; increment(); console.log(obj.count); // 1 console.log(window.count); // global count value: 1 var newObj = {count:50}; increment.call(newObj); console.log(newObj.count); // 51 obj.logAfterTimeout();// global count value: 1 obj.logAfterTimeout = function () { var proxiedFunction = $.proxy(function () { console.log(this.count); }, this); setTimeout(proxiedFunction, 1); }; obj.logAfterTimeout(); // 1 obj.logAfterTimeout = function () { var that = this; setTimeout(function () { console.log(that.count); }, 1); }; obj.logAfterTimeout(); // 1 The last couple of examples here demonstrate some methods for making sure you get the values you expect.  The first time logAfterTimeout is redefined, we use jQuery.proxy to create a new function which has its this permanently set to the passed in value (in this case, the current this).  The second time logAfterTimeout is redefined, we save the value of this in a variable (named that in this case, also often named self) and use the new variable in place of this. Now, all of this is to clarify what’s going on when you use this.  However, it’s pretty easy to avoid using this altogether in your code (especially in the way I’ve demonstrated above).  Instead of using this.count all over the place, it would have been much easier if I’d made count a variable instead of a property, and then I wouldn’t have to use this to refer to it.  var obj = (function () { var count = 0; return { increment: function () { count += 1; }, logAfterTimeout = function () { setTimeout(function () { console.log(count); }, 1); }, getCount: function () { return count; } }; }()); If you’re writing your code in this way, the main place you’ll run into issues with this is when handling DOM events (where this is the element on which the event occurred).  In that case, just be careful when using a callback within that event handler, that you’re not expecting this to still refer to the element (and use proxy or that/self if you need to refer to it). Finally, as demonstrated in the example, you can use call or apply on a function to set its this value.  This isn’t often needed, but you may also want to know that you can use apply to pass in an array of arguments to a function (e.g. console.log.apply(console, [1, 2, 3, 4])).

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• Automated SSRS deployment with the RS utility

  - by Stacy Vicknair

  If you’re familiar with SSRS and development you are probably aware of the SSRS web services. The RS utility is a tool that comes with SSRS that allows for scripts to be executed against against the SSRS web service without needing to create an application to consume the service. One of the better benefits of using this format rather than writing an application is that the script can be modified by others who might be involved in the creation and addition of scripts or management of the SSRS environment.   Reporting Services Scripter Jasper Smith from http://www.sqldbatips.com created Reporting Services Scripter to assist with the created of a batch process to deploy an entire SSRS environment. The helper scripts below were created through the modification of his generated scripts. Why not just use this tool? You certainly can. For me, the volume of scripts generated seems less maintainable than just using some common methods extracted from these scripts and creating a deployment in a single script file. I would, however, recommend this as a product if you do not think that your environment will change drastically or if you do not need to deploy with a higher level of control over the deployment. If you just need to replicate, this tool works great. Executing with RS.exe Executing a script against rs.exe is fairly simple. The Script Half the battle is having a starting point. For the scripting I needed to do the below is the starter script. A few notes: This script assumes integrated security. This script assumes your reports have one data source each. Both of the above are just what made sense for my scenario and are definitely modifiable to accommodate your needs. If you are unsure how to change the scripts to your needs, I recommend Reporting Services Scripter to help you understand how the differences. The script has three main methods: CreateFolder, CreateDataSource and CreateReport. Scripting the server deployment is just a process of recreating all of the elements that you need through calls to these methods. If there are additional elements that you need to deploy that aren’t covered by these methods, again I suggest using Reporting Services Scripter to get the code you would need, convert it to a repeatable method and add it to this script! Public Sub Main() CreateFolder("/", "Data Sources") CreateFolder("/", "My Reports") CreateDataSource("/Data Sources", "myDataSource", _ "Data Source=server\instance;Initial Catalog=myDatabase") CreateReport("/My Reports", _ "MyReport", _ "C:\myreport.rdl", _ True, _ "/Data Sources", _ "myDataSource") End Sub   Public Sub CreateFolder(parent As String, name As String) Dim fullpath As String = GetFullPath(parent, name) Try RS.CreateFolder(name, parent, GetCommonProperties()) Console.WriteLine("Folder created: {0}", name) Catch e As SoapException If e.Detail.Item("ErrorCode").InnerText = "rsItemAlreadyExists" Then Console.WriteLine("Folder {0} already exists and cannot be overwritten", fullpath) Else Console.WriteLine("Error : " + e.Detail.Item("ErrorCode").InnerText + " (" + e.Detail.Item("Message").InnerText + ")") End If End Try End Sub   Public Sub CreateDataSource(parent As String, name As String, connectionString As String) Try RS.CreateDataSource(name, parent,False, GetDataSourceDefinition(connectionString), GetCommonProperties()) Console.WriteLine("DataSource {0} created successfully", name) Catch e As SoapException Console.WriteLine("Error : " + e.Detail.Item("ErrorCode").InnerText + " (" + e.Detail.Item("Message").InnerText + ")") End Try End Sub   Public Sub CreateReport(parent As String, name As String, location As String, overwrite As Boolean, dataSourcePath As String, dataSourceName As String) Dim reportContents As Byte() = Nothing Dim warnings As Warning() = Nothing Dim fullpath As String = GetFullPath(parent, name)   'Read RDL definition from disk Try Dim stream As FileStream = File.OpenRead(location) reportContents = New [Byte](stream.Length-1) {} stream.Read(reportContents, 0, CInt(stream.Length)) stream.Close()   warnings = RS.CreateReport(name, parent, overwrite, reportContents, GetCommonProperties())   If Not (warnings Is Nothing) Then Dim warning As Warning For Each warning In warnings Console.WriteLine(Warning.Message) Next warning Else Console.WriteLine("Report: {0} published successfully with no warnings", name) End If   'Set report DataSource references Dim dataSources(0) As DataSource   Dim dsr0 As New DataSourceReference dsr0.Reference = dataSourcePath Dim ds0 As New DataSource ds0.Item = CType(dsr0, DataSourceDefinitionOrReference) ds0.Name=dataSourceName dataSources(0) = ds0     RS.SetItemDataSources(fullpath, dataSources)   Console.Writeline("Report DataSources set successfully")       Catch e As IOException Console.WriteLine(e.Message) Catch e As SoapException Console.WriteLine("Error : " + e.Detail.Item("ErrorCode").InnerText + " (" + e.Detail.Item("Message").InnerText + ")") End Try End Sub     Public Function GetCommonProperties() As [Property]() 'Common CatalogItem properties Dim descprop As New [Property] descprop.Name = "Description" descprop.Value = "" Dim hiddenprop As New [Property] hiddenprop.Name = "Hidden" hiddenprop.Value = "False"   Dim props(1) As [Property] props(0) = descprop props(1) = hiddenprop Return props End Function   Public Function GetDataSourceDefinition(connectionString as String) Dim definition As New DataSourceDefinition definition.CredentialRetrieval = CredentialRetrievalEnum.Integrated definition.ConnectString = connectionString definition.Enabled = True definition.EnabledSpecified = True definition.Extension = "SQL" definition.ImpersonateUser = False definition.ImpersonateUserSpecified = True definition.Prompt = "Enter a user name and password to access the data source:" definition.WindowsCredentials = False definition.OriginalConnectStringExpressionBased = False definition.UseOriginalConnectString = False Return definition End Function   Private Function GetFullPath(parent As String, name As String) As String If parent = "/" Then Return parent + name Else Return parent + "/" + name End If End Function

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• hide the console window when use batch file to launch a java program?

  - by 5YrsLaterDBA

  I use a batch to launch my java application like this start /min java -splash:resources\images\splash\splash.gif com.myproj.MyProjApp exit There is still a icon on the taskbar. what I want is hide the console window and only add ONE icon which is my application on the taskbar when I click that batch file?

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• Managed server not starting up however Admin console is up.

  - by Preet

  Hi, Scenario: If i try to start the server as a window service it gives an error stating that ceradentials are not correct.However on correcting the credentials in boot.properties when i try to start the server again it gives the same error.Any alternative for starting the server.I gave the same username and password in my startup Script and Boot.properties. Scenario 2: If i start the server remotely through console then will it come up? Thanks in advance. Regards, Preet

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• Is there a version of GreaseMonkey that prints ALL errors to the console, like if the UserScript was

  - by MiffTheFox

  Is there a version of GreaseMonkey that prints ALL errors to the console, like if the UserScript was a real JavaScript? For example syntax errors?

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• Mono : Is it possible to host a web/wcf service from console application?

  - by funwithcoding

  I know with .NET we can host wcf service from a console application without the need of webservers like IIS or apache. Is it possible to do the same with Mono 2.6.1 on a RHEL 5 or CentOS? Any links to any documentation will be highly helpful.

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• do console apps run faster than windows based app?

  - by omair iqbal

  i am reletivly new to world of programming i have a few performance questions 1. do console apps run faster than windows based app? 2.are languages like c and pascal faster than object oriented languages like c++ and delphi?i know language speed depends more on compiler than on language itself but do compilers for prcedural languages like c and pascal produce faster code than oo ones like delphi,c++(including c++ compilers that can procuce c code) sorry for my bad english

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• How to set session variables with app.get() in Ruby on Rails console?

  - by Vikrant Chaudhary

  How can I manually set session while calling app.get() in script/console? For example I want to access an authorised page, but it always redirects me to sign-in page. How can I set the session before calling app.get() so that I can make an authorised call to that page?

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• Restart program from a certain line with an if statement?

  - by user1744093

  could anyone help me restart my program from line 46 if the user enters 1 (just after the comment where it states that the next code is going to ask the user for 2 inputs) and if the user enters -1 end it. I cannot think how to do it. I'm new to C# any help you could give would be great! class Program { static void Main(string[] args) { //Displays data in correct Format List<float> inputList = new List<float>(); TextReader tr = new StreamReader("c:/users/tom/documents/visual studio 2010/Projects/DistanceCalculator3/DistanceCalculator3/TextFile1.txt"); String input = Convert.ToString(tr.ReadToEnd()); String[] items = input.Split(','); Console.WriteLine("Point Latitude Longtitude Elevation"); for (int i = 0; i < items.Length; i++) { if (i % 3 == 0) { Console.Write((i / 3) + "\t\t"); } Console.Write(items[i]); Console.Write("\t\t"); if (((i - 2) % 3) == 0) { Console.WriteLine(); } } Console.WriteLine(); Console.WriteLine(); // Ask for two inputs from the user which is then converted into 6 floats and transfered in class Coordinates Console.WriteLine("Please enter the two points that you wish to know the distance between:"); string point = Console.ReadLine(); string[] pointInput = point.Split(' '); int pointNumber = Convert.ToInt16(pointInput[0]); int pointNumber2 = Convert.ToInt16(pointInput[1]); Coordinates distance = new Coordinates(); distance.latitude = (Convert.ToDouble(items[pointNumber * 3])); distance.longtitude = (Convert.ToDouble(items[(pointNumber * 3) + 1])); distance.elevation = (Convert.ToDouble(items[(pointNumber * 3) + 2])); distance.latitude2 = (Convert.ToDouble(items[pointNumber2 * 3])); distance.longtitude2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 1])); distance.elevation2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 2])); //Calculate the distance between two points const double PIx = 3.141592653589793; const double RADIO = 6371; double dlat = ((distance.latitude2) * (PIx / 180)) - ((distance.latitude) * (PIx / 180)); double dlon = ((distance.longtitude2) * (PIx / 180)) - ((distance.longtitude) * (PIx / 180)); double a = (Math.Sin(dlat / 2) * Math.Sin(dlat / 2)) + Math.Cos((distance.latitude) * (PIx / 180)) * Math.Cos((distance.latitude2) * (PIx / 180)) * (Math.Sin(dlon / 2) * Math.Sin(dlon / 2)); double angle = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a)); double ultimateDistance = (angle * RADIO); Console.WriteLine("The distance between your two points is..."); Console.WriteLine(ultimateDistance); //Repeat the program if the user enters 1, end the program if the user enters -1 Console.WriteLine("If you wish to calculate another distance type 1 and return, if you wish to end the program, type -1."); Console.ReadLine(); if (Convert.ToInt16(Console.ReadLine()) == 1); { //here is where I need it to repeat }

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• Ecmascript 5 Date.parse for ISO 8601 test cases

  - by 4esn0k

  What results is right for next test cases? //Chrome Opera Firefox IE 9 Safari console.log(Date.parse("2012-11-31T23:59:59.000Z"));//1354406399000 NaN NaN 1354406399000 NaN console.log(Date.parse("2012-12-31T23:59:59.000Z"));//1356998399000 1356998399000 1356998399000 1356998399000 1356998399000 console.log(Date.parse("2012-12-31T23:59:60.000Z"));//NaN NaN NaN NaN 1356998400000 console.log(Date.parse("2012-04-04T05:02:02.170Z"));//1333515722170 1333515722170 1333515722170 1333515722170 1333515722170 console.log(Date.parse("2012-04-04T24:00:00.000Z"));//NaN 1333584000000 1333584000000 1333584000000 1333584000000 console.log(Date.parse("2012-04-04T24:00:00.500Z"));//NaN NaN 1333584000500 1333584000500 NaN

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• Glassfish v21 - is there a way to customize admin console login page per domain?

  - by ring bearer

  I have two to three domains under a single glassfish installation. Is there a known way to customize admin console login page based on the domain I am trying to administrator? (host/port)

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