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• AS3 - Can I know if a class implements an interface (or is a subclass of another class) ?

  - by lk

  With this code function someFunction(classParam:Class):Boolean { // how to know if classParam implements some interface? } i.e. Comparing classParam with IEventDispatcher interface: someFunction(EventDispatcher) // returns true someFunction(Object) // returns false I know it can't be done with is operator. But, is there a way to do it? Is there a way to know if a class implements some interface? (or is a subclass of another class?)

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• neww help with MSSQL select statement

  - by gio_333m

  Hello, I need help with select statement in MSSQL. My table looks like this: Id (int) QuestionId (int) GenreId (int) I want to select random N rows from this table so that maximum number of same GenreId in the result set is less than X for all GenreId-s except one. For that one GenreId, I need row count with that GenreId to be equal to Y. Thanks in advance

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• sql 2008 query. I am trying to correct this error message

  - by getbruce

  What is wrong with this code? What would be the correct syntax? SELECT EmployeeID, SUM('More than 2 orders') FROM Orders WHERE EmployeeID 2 GROUP BY EmployeeID Msg 8117, Level 16, State 1, Line 1 Operand data type varchar is invalid for sum operator.

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• how to substract two sums based on different field values in one table (view)

  - by user1749640

  example: i need the numbers of which the sum of the amount where id = 1 is not equal of the sum of the amount where id < 1, together with the id's and difference. The table (view in this case) may look like this: NUMBER AMOUNT ID 0001 500 1 0001 500 2 0002 400 3 0003 299 1 0003 300 3 0003 300 3 Many thanks for your help on this one.

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• Explain this PHP shorthand

  - by editor

  I feed like a goof but I don't entirely understand what's happening in this code: $var .= ($one || $two) ? function_one( $one, $another) : function_two( $two, $another); Does that say if $one or $two then $var is equal to fuction_one(), else function_two()? What's the purpose of using this syntax -- speed?

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• Interview Question : to find a result array where ith element is the product of all other elements e

  - by frictionlesspulley

  There is an array A[N] of N numbers. You have to compose an array Output[N] such that Output[i] will be equal to multiplication of all the elements of A[N] except A[i]. For example Output[0] will be multiplication of A[1] to A[N-1] and Output[1] will be multiplication of A[0] and from A[2] to A[N-1]. Solve it without division operator and in O(n).

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• jquery: most efficient way to get and store the ids of 100+ td items?

  - by Haroldo

  Ok so I have about six of these calendars on page, so thats around 180 td items (1 for each date): each td has an id that is equal to that day's timestamp. the dates I want are the red ones (class of .booked). So i need the fastest way to 'serialize' the ids for td.booked items, any ideas?

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• c programming Language [closed]

  - by ash89

  Write a program in C program to find the sum of the following: The input contain a sequence of two or more positive integers terminated by -1. Write a piece of code to count the ‘incidences’ in this sequence (i.e. the number of pairs of equal, adjacent numbers). For example, the following sequence contains 4 incidences: 4 2 9 9 3 7 7 7 3 3 -1

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• how to print numbers using for loop in java?

  - by Balkrushn Viroja

  I have one text box in which I take the value of how many number do you want to print. Now My question is that how can I use for loop so that the number which I want to print is equal to the number that I got from textbox.One more thing is that i want to print only three numbers in one line. i.e. If I got 14 in my text box the result will look like below. 1 2 3 4 5 6 7 8 9 10 11 12 13 14

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• Are <%: and <%= the same thing as embbed code (expression) blocks

  - by Ralph Shillington

  Having just started with MVC 2 I notice that in their starter template they use <%: Html.ActionLink("Home", "Index", "Home")%> and I was sure that in MVC 1 it was <%= Html.ActionLink("Home", "Index", "Home")%> Are they the same thing? If so, why the change from equal sign to colon.

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• VC++ 6.0 application crashing inside CString::Format when %d is given.

  - by viswanathan

  A VC++ 6.0 application is crashing when doing a CString::Format operation with %d format specifier. This does not occur always but occurs when the application memory grows upto 100MB or more. ALso sometimes same crash observed when a CString copy is done. The call stack would look like this mfc42u!CFixedAlloc::Alloc+82 mfc42u!CString::AllocBuffer+3f 00000038 00000038 005b5b64 mfc42u!CString::AllocBeforeWrite+31 00000038 0a5bfdbc 005b5b64 mfc42u!CString::AssignCopy+13 00000038 057cb83f 0a5bfe90 mfc42u!CString::operator=+4b and this throws an access violation exception.

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• Design by Contract with Microsoft .Net Code Contract

  - by Fredrik N

  I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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• Creating a thematic map

  - by jsharma

  This post describes how to create a simple thematic map, just a state population layer, with no underlying map tile layer. The map shows states color-coded by total population. The map is interactive with info-windows and can be panned and zoomed. The sample code demonstrates the following: Displaying an interactive vector layer with no background map tile layer (i.e. purpose and use of the Universe object) Using a dynamic (i.e. defined via the javascript client API) color bucket style Dynamically changing a layer's rendering style Specifying which attribute value to use in determining the bucket, and hence style, for a feature (FoI) The result is shown in the screenshot below. The states layer was defined, and stored in the user_sdo_themes view of the mvdemo schema, using MapBuilder. The underlying table is defined as SQL> desc states_32775  Name                                      Null?    Type ----------------------------------------- -------- ----------------------------  STATE                                              VARCHAR2(26)  STATE_ABRV                                         VARCHAR2(2) FIPSST                                             VARCHAR2(2) TOTPOP                                             NUMBER PCTSMPLD                                           NUMBER LANDSQMI                                           NUMBER POPPSQMI                                           NUMBER ... MEDHHINC NUMBER AVGHHINC NUMBER GEOM32775 MDSYS.SDO_GEOMETRY We'll use the TOTPOP column value in the advanced (color bucket) style for rendering the states layers. The predefined theme (US_STATES_BI) is defined as follows. SQL> select styling_rules from user_sdo_themes where name='US_STATES_BI'; STYLING_RULES -------------------------------------------------------------------------------- <?xml version="1.0" standalone="yes"?> <styling_rules highlight_style="C.CB_QUAL_8_CLASS_DARK2_1"> <hidden_info> <field column="STATE" name="Name"/> <field column="POPPSQMI" name="POPPSQMI"/> <field column="TOTPOP" name="TOTPOP"/> </hidden_info> <rule column="TOTPOP"> <features style="states_totpop"> </features> <label column="STATE_ABRV" style="T.BLUE_SERIF_10"> 1 </label> </rule> </styling_rules> SQL> The theme definition specifies that the state, poppsqmi, totpop, state_abrv, and geom columns will be queried from the states_32775 table. The state_abrv value will be used to label the state while the totpop value will be used to determine the color-fill from those defined in the states_totpop advanced style. The states_totpop style, which we will not use in our demo, is defined as shown below. SQL> select definition from user_sdo_styles where name='STATES_TOTPOP'; DEFINITION -------------------------------------------------------------------------------- <?xml version="1.0" ?> <AdvancedStyle> <BucketStyle> <Buckets default_style="C.S02_COUNTRY_AREA"> <RangedBucket seq="0" label="10K - 5M" low="10000" high="5000000" style="C.SEQ6_01" /> <RangedBucket seq="1" label="5M - 12M" low="5000001" high="1.2E7" style="C.SEQ6_02" /> <RangedBucket seq="2" label="12M - 20M" low="1.2000001E7" high="2.0E7" style="C.SEQ6_04" /> <RangedBucket seq="3" label="&gt; 20M" low="2.0000001E7" high="5.0E7" style="C.SEQ6_05" /> </Buckets> </BucketStyle> </AdvancedStyle> SQL> The demo defines additional advanced styles via the OM.style object and methods and uses those instead when rendering the states layer.   Now let's look at relevant snippets of code that defines the map extent and zoom levels (i.e. the OM.universe),  loads the states predefined vector layer (OM.layer), and sets up the advanced (color bucket) style. Defining the map extent and zoom levels. function initMap() {   //alert("Initialize map view");     // define the map extent and number of zoom levels.   // The Universe object is similar to the map tile layer configuration   // It defines the map extent, number of zoom levels, and spatial reference system   // well-known ones (like web mercator/google/bing or maps.oracle/elocation are predefined   // The Universe must be defined when there is no underlying map tile layer.   // When there is a map tile layer then that defines the map extent, srid, and zoom levels.      var uni= new OM.universe.Universe(     {         srid : 32775,         bounds : new OM.geometry.Rectangle(                         -3280000, 170000, 2300000, 3200000, 32775),         numberOfZoomLevels: 8     }); The srid specifies the spatial reference system which is Equal-Area Projection (United States). SQL> select cs_name from cs_srs where srid=32775 ; CS_NAME --------------------------------------------------- Equal-Area Projection (United States) The bounds defines the map extent. It is a Rectangle defined using the lower-left and upper-right coordinates and srid. Loading and displaying the states layer This is done in the states() function. The full code is at the end of this post, however here's the snippet which defines the states VectorLayer.     // States is a predefined layer in user_sdo_themes     var  layer2 = new OM.layer.VectorLayer("vLayer2",     {         def:         {             type:OM.layer.VectorLayer.TYPE_PREDEFINED,             dataSource:"mvdemo",             theme:"us_states_bi",             url: baseURL,             loadOnDemand: false         },         boundingTheme:true      }); The first parameter is a layer name, the second is an object literal for a layer config. The config object has two attributes: the first is the layer definition, the second specifies whether the layer is a bounding one (i.e. used to determine the current map zoom and center such that the whole layer is displayed within the map window) or not. The layer config has the following attributes: type - specifies whether is a predefined one, a defined via a SQL query (JDBC), or in a json-format file (DATAPACK) theme - is the predefined theme's name url - is the location of the mapviewer server loadOnDemand - specifies whether to load all the features or just those that lie within the current map window and load additional ones as needed on a pan or zoom The code snippet below dynamically defines an advanced style and then uses it, instead of the 'states_totpop' style, when rendering the states layer. // override predefined rendering style with programmatic one    var theRenderingStyle =      createBucketColorStyle('YlBr5', colorSeries, 'States5', true);   // specify which attribute is used in determining the bucket (i.e. color) to use for the state   // It can be an array because the style could be a chart type (pie/bar)   // which requires multiple attribute columns     // Use the STATE.TOTPOP column (aka attribute) value here    layer2.setRenderingStyle(theRenderingStyle, ["TOTPOP"]); The style itself is defined in the createBucketColorStyle() function. Dynamically defining an advanced style The advanced style used here is a bucket color style, i.e. a color style is associated with each bucket. So first we define the colors and then the buckets.     numClasses = colorSeries[colorName].classes;    // create Color Styles    for (var i=0; i < numClasses; i++)    {         theStyles[i] = new OM.style.Color(                      {fill: colorSeries[colorName].fill[i],                        stroke:colorSeries[colorName].stroke[i],                       strokeOpacity: useGradient? 0.25 : 1                      });    }; numClasses is the number of buckets. The colorSeries array contains the color fill and stroke definitions and is: var colorSeries = { //multi-hue color scheme #10 YlBl. "YlBl3": {   classes:3,                  fill: [0xEDF8B1, 0x7FCDBB, 0x2C7FB8],                  stroke:[0xB5DF9F, 0x72B8A8, 0x2872A6]   }, "YlBl5": {   classes:5,                  fill:[0xFFFFCC, 0xA1DAB4, 0x41B6C4, 0x2C7FB8, 0x253494],                  stroke:[0xE6E6B8, 0x91BCA2, 0x3AA4B0, 0x2872A6, 0x212F85]   }, //multi-hue color scheme #11 YlBr.  "YlBr3": {classes:3,                  fill:[0xFFF7BC, 0xFEC44F, 0xD95F0E],                  stroke:[0xE6DEA9, 0xE5B047, 0xC5360D]   }, "YlBr5": {classes:5,                  fill:[0xFFFFD4, 0xFED98E, 0xFE9929, 0xD95F0E, 0x993404],                  stroke:[0xE6E6BF, 0xE5C380, 0xE58A25, 0xC35663, 0x8A2F04]     }, etc. Next we create the bucket style.    bucketStyleDef = {       numClasses : colorSeries[colorName].classes, //      classification: 'custom',  //since we are supplying all the buckets //      buckets: theBuckets,       classification: 'logarithmic',  // use a logarithmic scale       styles: theStyles,       gradient:  useGradient? 'linear' : 'off' //      gradient:  useGradient? 'radial' : 'off'     };    theBucketStyle = new OM.style.BucketStyle(bucketStyleDef);    return theBucketStyle; A BucketStyle constructor takes a style definition as input. The style definition specifies the number of buckets (numClasses), a classification scheme (which can be equal-ranged, logarithmic scale, or custom), the styles for each bucket, whether to use a gradient effect, and optionally the buckets (required when using a custom classification scheme). The full source for the demo <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Oracle Maps V2 Thematic Map Demo</title> <script src="http://localhost:8080/mapviewer/jslib/v2/oraclemapsv2.js" type="text/javascript"> </script> <script type="text/javascript"> //var $j = jQuery.noConflict(); var baseURL="http://localhost:8080/mapviewer"; // location of mapviewer OM.gv.proxyEnabled =false; // no mvproxy needed OM.gv.setResourcePath(baseURL+"/jslib/v2/images/"); // location of resources for UI elements like nav panel buttons var map = null; // the client mapviewer object var statesLayer = null, stateCountyLayer = null; // The vector layers for states and counties in a state var layerName="States"; // initial map center and zoom var mapCenterLon = -20000; var mapCenterLat = 1750000; var mapZoom = 2; var mpoint = new OM.geometry.Point(mapCenterLon,mapCenterLat,32775); var currentPalette = null, currentStyle=null; // set an onchange listener for the color palette select list // initialize the map // load and display the states layer $(document).ready( function() { $("#demo-htmlselect").change(function() { var theColorScheme = $(this).val(); useSelectedColorScheme(theColorScheme); }); initMap(); states(); } ); /** * color series from ColorBrewer site (http://colorbrewer2.org/). */ var colorSeries = { //multi-hue color scheme #10 YlBl. "YlBl3": { classes:3, fill: [0xEDF8B1, 0x7FCDBB, 0x2C7FB8], stroke:[0xB5DF9F, 0x72B8A8, 0x2872A6] }, "YlBl5": { classes:5, fill:[0xFFFFCC, 0xA1DAB4, 0x41B6C4, 0x2C7FB8, 0x253494], stroke:[0xE6E6B8, 0x91BCA2, 0x3AA4B0, 0x2872A6, 0x212F85] }, //multi-hue color scheme #11 YlBr. "YlBr3": {classes:3, fill:[0xFFF7BC, 0xFEC44F, 0xD95F0E], stroke:[0xE6DEA9, 0xE5B047, 0xC5360D] }, "YlBr5": {classes:5, fill:[0xFFFFD4, 0xFED98E, 0xFE9929, 0xD95F0E, 0x993404], stroke:[0xE6E6BF, 0xE5C380, 0xE58A25, 0xC35663, 0x8A2F04] }, // single-hue color schemes (blues, greens, greys, oranges, reds, purples) "Purples5": {classes:5, fill:[0xf2f0f7, 0xcbc9e2, 0x9e9ac8, 0x756bb1, 0x54278f], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] }, "Blues5": {classes:5, fill:[0xEFF3FF, 0xbdd7e7, 0x68aed6, 0x3182bd, 0x18519C], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] }, "Greens5": {classes:5, fill:[0xedf8e9, 0xbae4b3, 0x74c476, 0x31a354, 0x116d2c], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] }, "Greys5": {classes:5, fill:[0xf7f7f7, 0xcccccc, 0x969696, 0x636363, 0x454545], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] }, "Oranges5": {classes:5, fill:[0xfeedde, 0xfdb385, 0xfd8d3c, 0xe6550d, 0xa63603], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] }, "Reds5": {classes:5, fill:[0xfee5d9, 0xfcae91, 0xfb6a4a, 0xde2d26, 0xa50f15], stroke:[0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3, 0xd3d3d3] } }; function createBucketColorStyle( colorName, colorSeries, rangeName, useGradient) { var theBucketStyle; var bucketStyleDef; var theStyles = []; var theColors = []; var aBucket, aStyle, aColor, aRange; var numClasses ; numClasses = colorSeries[colorName].classes; // create Color Styles for (var i=0; i < numClasses; i++) { theStyles[i] = new OM.style.Color( {fill: colorSeries[colorName].fill[i], stroke:colorSeries[colorName].stroke[i], strokeOpacity: useGradient? 0.25 : 1 }); }; bucketStyleDef = { numClasses : colorSeries[colorName].classes, // classification: 'custom', //since we are supplying all the buckets // buckets: theBuckets, classification: 'logarithmic', // use a logarithmic scale styles: theStyles, gradient: useGradient? 'linear' : 'off' // gradient: useGradient? 'radial' : 'off' }; theBucketStyle = new OM.style.BucketStyle(bucketStyleDef); return theBucketStyle; } function initMap() { //alert("Initialize map view"); // define the map extent and number of zoom levels. // The Universe object is similar to the map tile layer configuration // It defines the map extent, number of zoom levels, and spatial reference system // well-known ones (like web mercator/google/bing or maps.oracle/elocation are predefined // The Universe must be defined when there is no underlying map tile layer. // When there is a map tile layer then that defines the map extent, srid, and zoom levels. var uni= new OM.universe.Universe( { srid : 32775, bounds : new OM.geometry.Rectangle( -3280000, 170000, 2300000, 3200000, 32775), numberOfZoomLevels: 8 }); map = new OM.Map( document.getElementById('map'), { mapviewerURL: baseURL, universe:uni }) ; var navigationPanelBar = new OM.control.NavigationPanelBar(); map.addMapDecoration(navigationPanelBar); } // end initMap function states() { //alert("Load and display states"); layerName = "States"; if(statesLayer) { // states were already visible but the style may have changed // so set the style to the currently selected one var theData = $('#demo-htmlselect').val(); setStyle(theData); } else { // States is a predefined layer in user_sdo_themes var layer2 = new OM.layer.VectorLayer("vLayer2", { def: { type:OM.layer.VectorLayer.TYPE_PREDEFINED, dataSource:"mvdemo", theme:"us_states_bi", url: baseURL, loadOnDemand: false }, boundingTheme:true }); // add drop shadow effect and hover style var shadowFilter = new OM.visualfilter.DropShadow({opacity:0.5, color:"#000000", offset:6, radius:10}); var hoverStyle = new OM.style.Color( {stroke:"#838383", strokeThickness:2}); layer2.setHoverStyle(hoverStyle); layer2.setHoverVisualFilter(shadowFilter); layer2.enableFeatureHover(true); layer2.enableFeatureSelection(false); layer2.setLabelsVisible(true); // override predefined rendering style with programmatic one var theRenderingStyle = createBucketColorStyle('YlBr5', colorSeries, 'States5', true); // specify which attribute is used in determining the bucket (i.e. color) to use for the state // It can be an array because the style could be a chart type (pie/bar) // which requires multiple attribute columns // Use the STATE.TOTPOP column (aka attribute) value here layer2.setRenderingStyle(theRenderingStyle, ["TOTPOP"]); currentPalette = "YlBr5"; var stLayerIdx = map.addLayer(layer2); //alert('State Layer Idx = ' + stLayerIdx); map.setMapCenter(mpoint); map.setMapZoomLevel(mapZoom) ; // display the map map.init() ; statesLayer=layer2; // add rt-click event listener to show counties for the state layer2.addListener(OM.event.MouseEvent.MOUSE_RIGHT_CLICK,stateRtClick); } // end if } // end states function setStyle(styleName) { // alert("Selected Style = " + styleName); // there may be a counties layer also displayed. // that wll have different bucket ranges so create // one style for states and one for counties var newRenderingStyle = null; if (layerName === "States") { if(/3/.test(styleName)) { newRenderingStyle = createBucketColorStyle(styleName, colorSeries, 'States3', false); currentStyle = createBucketColorStyle(styleName, colorSeries, 'Counties3', false); } else { newRenderingStyle = createBucketColorStyle(styleName, colorSeries, 'States5', false); currentStyle = createBucketColorStyle(styleName, colorSeries, 'Counties5', false); } statesLayer.setRenderingStyle(newRenderingStyle, ["TOTPOP"]); if (stateCountyLayer) stateCountyLayer.setRenderingStyle(currentStyle, ["TOTPOP"]); } } // end setStyle function stateRtClick(evt){ var foi = evt.feature; //alert('Rt-Click on State: ' + foi.attributes['_label_'] + // ' with pop ' + foi.attributes['TOTPOP']); // display another layer with counties info // layer may change on each rt-click so create and add each time. var countyByState = null ; // the _label_ attribute of a feature in this case is the state abbreviation // we will use that to query and get the counties for a state var sqlText = "select totpop,geom32775 from counties_32775_moved where state_abrv="+ "'"+foi.getAttributeValue('_label_')+"'"; // alert(sqlText); if (currentStyle === null) currentStyle = createBucketColorStyle('YlBr5', colorSeries, 'Counties5', false); /* try a simple style instead new OM.style.ColorStyle( { stroke: "#B8F4FF", fill: "#18E5F4", fillOpacity:0 } ); */ // remove existing layer if any if(stateCountyLayer) map.removeLayer(stateCountyLayer); countyByState = new OM.layer.VectorLayer("stCountyLayer", {def:{type:OM.layer.VectorLayer.TYPE_JDBC, dataSource:"mvdemo", sql:sqlText, url:baseURL}}); // url:baseURL}, // renderingStyle:currentStyle}); countyByState.setVisible(true); // specify which attribute is used in determining the bucket (i.e. color) to use for the state countyByState.setRenderingStyle(currentStyle, ["TOTPOP"]); var ctLayerIdx = map.addLayer(countyByState); // alert('County Layer Idx = ' + ctLayerIdx); //map.addLayer(countyByState); stateCountyLayer = countyByState; } // end stateRtClick function useSelectedColorScheme(theColorScheme) { if(map) { // code to update renderStyle goes here //alert('will try to change render style'); setStyle(theColorScheme); } else { // do nothing } } </script> </head> <body bgcolor="#b4c5cc" style="height:100%;font-family:Arial,Helvetica,Verdana"> <h3 align="center">State population thematic map </h3> <div id="demo" style="position:absolute; left:68%; top:44px; width:28%; height:100%"> <HR/> <p/> Choose Color Scheme: <select id="demo-htmlselect"> <option value="YlBl3"> YellowBlue3</option> <option value="YlBr3"> YellowBrown3</option> <option value="YlBl5"> YellowBlue5</option> <option value="YlBr5" selected="selected"> YellowBrown5</option> <option value="Blues5"> Blues</option> <option value="Greens5"> Greens</option> <option value="Greys5"> Greys</option> <option value="Oranges5"> Oranges</option> <option value="Purples5"> Purples</option> <option value="Reds5"> Reds</option> </select> <p/> </div> <div id="map" style="position:absolute; left:10px; top:50px; width:65%; height:75%; background-color:#778f99"></div> <div style="position:absolute;top:85%; left:10px;width:98%" class="noprint"> <HR/> <p> Note: This demo uses HTML5 Canvas and requires IE9+, Firefox 10+, or Chrome. No map will show up in IE8 or earlier. </p> </div> </body> </html>

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• Using R to Analyze G1GC Log Files

  - by user12620111

  Using R to Analyze G1GC Log Files body, td { font-family: sans-serif; background-color: white; font-size: 12px; margin: 8px; } tt, code, pre { font-family: 'DejaVu Sans Mono', 'Droid Sans Mono', 'Lucida Console', Consolas, Monaco, monospace; } h1 { font-size:2.2em; } h2 { font-size:1.8em; } h3 { font-size:1.4em; } h4 { font-size:1.0em; } h5 { font-size:0.9em; } h6 { font-size:0.8em; } a:visited { color: rgb(50%, 0%, 50%); } pre { margin-top: 0; max-width: 95%; border: 1px solid #ccc; white-space: pre-wrap; } pre code { display: block; padding: 0.5em; } code.r, code.cpp { background-color: #F8F8F8; } table, td, th { border: none; } blockquote { color:#666666; margin:0; padding-left: 1em; border-left: 0.5em #EEE solid; } hr { height: 0px; border-bottom: none; border-top-width: thin; border-top-style: dotted; border-top-color: #999999; } @media print { * { background: transparent !important; color: black !important; filter:none !important; -ms-filter: none !important; } body { 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  Using R to Analyze G1GC Log Files   Using R to Analyze G1GC Log Files Introduction Working in Oracle Platform Integration gives an engineer opportunities to work on a wide array of technologies. My team’s goal is to make Oracle applications run best on the Solaris/SPARC platform. When looking for bottlenecks in a modern applications, one needs to be aware of not only how the CPUs and operating system are executing, but also network, storage, and in some cases, the Java Virtual Machine. I was recently presented with about 1.5 GB of Java Garbage First Garbage Collector log file data. If you’re not familiar with the subject, you might want to review Garbage First Garbage Collector Tuning by Monica Beckwith. The customer had been running Java HotSpot 1.6.0_31 to host a web application server. I was told that the Solaris/SPARC server was running a Java process launched using a commmand line that included the following flags: -d64 -Xms9g -Xmx9g -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=80 -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintGCDateStamps -XX:+PrintFlagsFinal -XX:+DisableExplicitGC -XX:+UnlockExperimentalVMOptions -XX:ParallelGCThreads=8 Several sources on the internet indicate that if I were to print out the 1.5 GB of log files, it would require enough paper to fill the bed of a pick up truck. Of course, it would be fruitless to try to scan the log files by hand. Tools will be required to summarize the contents of the log files. Others have encountered large Java garbage collection log files. There are existing tools to analyze the log files: IBM’s GC toolkit The chewiebug GCViewer gchisto HPjmeter Instead of using one of the other tools listed, I decide to parse the log files with standard Unix tools, and analyze the data with R. Data Cleansing The log files arrived in two different formats. I guess that the difference is that one set of log files was generated using a more verbose option, maybe -XX:+PrintHeapAtGC, and the other set of log files was generated without that option. Format 1 In some of the log files, the log files with the less verbose format, a single trace, i.e. the report of a singe garbage collection event, looks like this: {Heap before GC invocations=12280 (full 61): garbage-first heap total 9437184K, used 7499918K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 1 young (4096K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. 2014-05-14T07:24:00.988-0700: 60586.353: [GC pause (young) 7324M->7320M(9216M), 0.1567265 secs] Heap after GC invocations=12281 (full 61): garbage-first heap total 9437184K, used 7496533K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 0 young (0K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. } A simple grep can be used to extract a summary: $ grep "\[ GC pause (young" g1gc.log 2014-05-13T13:24:35.091-0700: 3.109: [GC pause (young) 20M->5029K(9216M), 0.0146328 secs] 2014-05-13T13:24:35.440-0700: 3.459: [GC pause (young) 9125K->6077K(9216M), 0.0086723 secs] 2014-05-13T13:24:37.581-0700: 5.599: [GC pause (young) 25M->8470K(9216M), 0.0203820 secs] 2014-05-13T13:24:42.686-0700: 10.704: [GC pause (young) 44M->15M(9216M), 0.0288848 secs] 2014-05-13T13:24:48.941-0700: 16.958: [GC pause (young) 51M->20M(9216M), 0.0491244 secs] 2014-05-13T13:24:56.049-0700: 24.066: [GC pause (young) 92M->26M(9216M), 0.0525368 secs] 2014-05-13T13:25:34.368-0700: 62.383: [GC pause (young) 602M->68M(9216M), 0.1721173 secs] But that format wasn't easily read into R, so I needed to be a bit more tricky. I used the following Unix command to create a summary file that was easy for R to read. $ echo "SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime" $ grep "\[GC pause (young" g1gc.log | grep -v mark | sed -e 's/[A-SU-z\(\),]/ /g' -e 's/->/ /' -e 's/: / /g' | more SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime 2014-05-13T13:24:35.091-0700 3.109 20 5029 9216 0.0146328 2014-05-13T13:24:35.440-0700 3.459 9125 6077 9216 0.0086723 2014-05-13T13:24:37.581-0700 5.599 25 8470 9216 0.0203820 2014-05-13T13:24:42.686-0700 10.704 44 15 9216 0.0288848 2014-05-13T13:24:48.941-0700 16.958 51 20 9216 0.0491244 2014-05-13T13:24:56.049-0700 24.066 92 26 9216 0.0525368 2014-05-13T13:25:34.368-0700 62.383 602 68 9216 0.1721173 Format 2 In some of the log files, the log files with the more verbose format, a single trace, i.e. the report of a singe garbage collection event, was more complicated than Format 1. Here is a text file with an example of a single G1GC trace in the second format. As you can see, it is quite complicated. It is nice that there is so much information available, but the level of detail can be overwhelming. I wrote this awk script (download) to summarize each trace on a single line. #!/usr/bin/env awk -f BEGIN { printf("SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize\n") } ###################### # Save count data from lines that are at the start of each G1GC trace. # Each trace starts out like this: # {Heap before GC invocations=14 (full 0): # garbage-first heap total 9437184K, used 325496K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) ###################### /{Heap.*full/{ gsub ( "\\)" , "" ); nf=split($0,a,"="); split(a[2],b," "); getline; if ( match($0, "first") ) { G1GC=1; IncrementalCount=b[1]; FullCount=substr( b[3], 1, length(b[3])-1 ); } else { G1GC=0; } } ###################### # Pull out time stamps that are in lines with this format: # 2014-05-12T14:02:06.025-0700: 94.312: [GC pause (young), 0.08870154 secs] ###################### /GC pause/ { DateTime=$1; SecondsSinceLaunch=substr($2, 1, length($2)-1); } ###################### # Heap sizes are in lines that look like this: # [ 4842M->4838M(9216M)] ###################### /\[ .*]$/ { gsub ( "\\[" , "" ); gsub ( "\ \]" , "" ); gsub ( "->" , " " ); gsub ( "\\( " , " " ); gsub ( "\ \)" , " " ); split($0,a," "); if ( split(a[1],b,"M") > 1 ) {BeforeSize=b[1]*1024;} if ( split(a[1],b,"K") > 1 ) {BeforeSize=b[1];} if ( split(a[2],b,"M") > 1 ) {AfterSize=b[1]*1024;} if ( split(a[2],b,"K") > 1 ) {AfterSize=b[1];} if ( split(a[3],b,"M") > 1 ) {TotalSize=b[1]*1024;} if ( split(a[3],b,"K") > 1 ) {TotalSize=b[1];} } ###################### # Emit an output line when you find input that looks like this: # [Times: user=1.41 sys=0.08, real=0.24 secs] ###################### /\[Times/ { if (G1GC==1) { gsub ( "," , "" ); split($2,a,"="); UserTime=a[2]; split($3,a,"="); SysTime=a[2]; split($4,a,"="); RealTime=a[2]; print DateTime,SecondsSinceLaunch,IncrementalCount,FullCount,UserTime,SysTime,RealTime,BeforeSize,AfterSize,TotalSize; G1GC=0; } } The resulting summary is about 25X smaller that the original file, but still difficult for a human to digest. SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ... 2014-05-12T18:36:34.669-0700: 3985.744 561 0 0.57 0.06 0.16 1724416 1720320 9437184 2014-05-12T18:36:34.839-0700: 3985.914 562 0 0.51 0.06 0.19 1724416 1720320 9437184 2014-05-12T18:36:35.069-0700: 3986.144 563 0 0.60 0.04 0.27 1724416 1721344 9437184 2014-05-12T18:36:35.354-0700: 3986.429 564 0 0.33 0.04 0.09 1725440 1722368 9437184 2014-05-12T18:36:35.545-0700: 3986.620 565 0 0.58 0.04 0.17 1726464 1722368 9437184 2014-05-12T18:36:35.726-0700: 3986.801 566 0 0.43 0.05 0.12 1726464 1722368 9437184 2014-05-12T18:36:35.856-0700: 3986.930 567 0 0.30 0.04 0.07 1726464 1723392 9437184 2014-05-12T18:36:35.947-0700: 3987.023 568 0 0.61 0.04 0.26 1727488 1723392 9437184 2014-05-12T18:36:36.228-0700: 3987.302 569 0 0.46 0.04 0.16 1731584 1724416 9437184 Reading the Data into R Once the GC log data had been cleansed, either by processing the first format with the shell script, or by processing the second format with the awk script, it was easy to read the data into R. g1gc.df = read.csv("summary.txt", row.names = NULL, stringsAsFactors=FALSE,sep="") str(g1gc.df) ## 'data.frame': 8307 obs. of 10 variables: ## $ row.names : chr "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ... ## $ SecondsSinceLaunch: num 1.16 1.47 1.97 3.83 6.1 ... ## $ IncrementalCount : int 0 1 2 3 4 5 6 7 8 9 ... ## $ FullCount : int 0 0 0 0 0 0 0 0 0 0 ... ## $ UserTime : num 0.11 0.05 0.04 0.21 0.08 0.26 0.31 0.33 0.34 0.56 ... ## $ SysTime : num 0.04 0.01 0.01 0.05 0.01 0.06 0.07 0.06 0.07 0.09 ... ## $ RealTime : num 0.02 0.02 0.01 0.04 0.02 0.04 0.05 0.04 0.04 0.06 ... ## $ BeforeSize : int 8192 5496 5768 22528 24576 43008 34816 53248 55296 93184 ... ## $ AfterSize : int 1400 1672 2557 4907 7072 14336 16384 18432 19456 21504 ... ## $ TotalSize : int 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 ... head(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount ## 1 2014-05-12T14:00:32.868-0700: 1.161 0 ## 2 2014-05-12T14:00:33.179-0700: 1.472 1 ## 3 2014-05-12T14:00:33.677-0700: 1.969 2 ## 4 2014-05-12T14:00:35.538-0700: 3.830 3 ## 5 2014-05-12T14:00:37.811-0700: 6.103 4 ## 6 2014-05-12T14:00:41.428-0700: 9.720 5 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 1 0 0.11 0.04 0.02 8192 1400 9437184 ## 2 0 0.05 0.01 0.02 5496 1672 9437184 ## 3 0 0.04 0.01 0.01 5768 2557 9437184 ## 4 0 0.21 0.05 0.04 22528 4907 9437184 ## 5 0 0.08 0.01 0.02 24576 7072 9437184 ## 6 0 0.26 0.06 0.04 43008 14336 9437184 Basic Statistics Once the data has been read into R, simple statistics are very easy to generate. All of the numbers from high school statistics are available via simple commands. For example, generate a summary of every column: summary(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount FullCount ## Length:8307 Min. : 1 Min. : 0 Min. : 0.0 ## Class :character 1st Qu.: 9977 1st Qu.:2048 1st Qu.: 0.0 ## Mode :character Median :12855 Median :4136 Median : 12.0 ## Mean :12527 Mean :4156 Mean : 31.6 ## 3rd Qu.:15758 3rd Qu.:6262 3rd Qu.: 61.0 ## Max. :55484 Max. :8391 Max. :113.0 ## UserTime SysTime RealTime BeforeSize ## Min. :0.040 Min. :0.0000 Min. : 0.0 Min. : 5476 ## 1st Qu.:0.470 1st Qu.:0.0300 1st Qu.: 0.1 1st Qu.:5137920 ## Median :0.620 Median :0.0300 Median : 0.1 Median :6574080 ## Mean :0.751 Mean :0.0355 Mean : 0.3 Mean :5841855 ## 3rd Qu.:0.920 3rd Qu.:0.0400 3rd Qu.: 0.2 3rd Qu.:7084032 ## Max. :3.370 Max. :1.5600 Max. :488.1 Max. :8696832 ## AfterSize TotalSize ## Min. : 1380 Min. :9437184 ## 1st Qu.:5002752 1st Qu.:9437184 ## Median :6559744 Median :9437184 ## Mean :5785454 Mean :9437184 ## 3rd Qu.:7054336 3rd Qu.:9437184 ## Max. :8482816 Max. :9437184 Q: What is the total amount of User CPU time spent in garbage collection? sum(g1gc.df$UserTime) ## [1] 6236 As you can see, less than two hours of CPU time was spent in garbage collection. Is that too much? To find the percentage of time spent in garbage collection, divide the number above by total_elapsed_time*CPU_count. In this case, there are a lot of CPU’s and it turns out the the overall amount of CPU time spent in garbage collection isn’t a problem when viewed in isolation. When calculating rates, i.e. events per unit time, you need to ask yourself if the rate is homogenous across the time period in the log file. Does the log file include spikes of high activity that should be separately analyzed? Averaging in data from nights and weekends with data from business hours may alias problems. If you have a reason to suspect that the garbage collection rates include peaks and valleys that need independent analysis, see the “Time Series” section, below. Q: How much garbage is collected on each pass? The amount of heap space that is recovered per GC pass is surprisingly low: At least one collection didn’t recover any data. (“Min.=0”) 25% of the passes recovered 3MB or less. (“1st Qu.=3072”) Half of the GC passes recovered 4MB or less. (“Median=4096”) The average amount recovered was 56MB. (“Mean=56390”) 75% of the passes recovered 36MB or less. (“3rd Qu.=36860”) At least one pass recovered 2GB. (“Max.=2121000”) g1gc.df$Delta = g1gc.df$BeforeSize - g1gc.df$AfterSize summary(g1gc.df$Delta) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0 3070 4100 56400 36900 2120000 Q: What is the maximum User CPU time for a single collection? The worst garbage collection (“Max.”) is many standard deviations away from the mean. The data appears to be right skewed. summary(g1gc.df$UserTime) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0.040 0.470 0.620 0.751 0.920 3.370 sd(g1gc.df$UserTime) ## [1] 0.3966 Basic Graphics Once the data is in R, it is trivial to plot the data with formats including dot plots, line charts, bar charts (simple, stacked, grouped), pie charts, boxplots, scatter plots histograms, and kernel density plots. Histogram of User CPU Time per Collection I don't think that this graph requires any explanation. hist(g1gc.df$UserTime, main="User CPU Time per Collection", xlab="Seconds", ylab="Frequency") Box plot to identify outliers When the initial data is viewed with a box plot, you can see the one crazy outlier in the real time per GC. Save this data point for future analysis and drop the outlier so that it’s not throwing off our statistics. Now the box plot shows many outliers, which will be examined later, using times series analysis. Notice that the scale of the x-axis changes drastically once the crazy outlier is removed. par(mfrow=c(2,1)) boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(dominated by a crazy outlier)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") crazy.outlier.df=g1gc.df[g1gc.df$RealTime > 400,] g1gc.df=g1gc.df[g1gc.df$RealTime < 400,] boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(crazy outlier excluded)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") box(which = "outer", lty = "solid") Here is the crazy outlier for future analysis: crazy.outlier.df ## row.names SecondsSinceLaunch IncrementalCount ## 8233 2014-05-12T23:15:43.903-0700: 20741 8316 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 8233 112 0.55 0.42 488.1 8381440 8235008 9437184 ## Delta ## 8233 146432 R Time Series Data To analyze the garbage collection as a time series, I’ll use Z’s Ordered Observations (zoo). “zoo is the creator for an S3 class of indexed totally ordered observations which includes irregular time series.” require(zoo) ## Loading required package: zoo ## ## Attaching package: 'zoo' ## ## The following objects are masked from 'package:base': ## ## as.Date, as.Date.numeric head(g1gc.df[,1]) ## [1] "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" ## [3] "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ## [5] "2014-05-12T14:00:37.811-0700:" "2014-05-12T14:00:41.428-0700:" options("digits.secs"=3) times=as.POSIXct( g1gc.df[,1], format="%Y-%m-%dT%H:%M:%OS%z:") g1gc.z = zoo(g1gc.df[,-c(1)], order.by=times) head(g1gc.z) ## SecondsSinceLaunch IncrementalCount FullCount ## 2014-05-12 17:00:32.868 1.161 0 0 ## 2014-05-12 17:00:33.178 1.472 1 0 ## 2014-05-12 17:00:33.677 1.969 2 0 ## 2014-05-12 17:00:35.538 3.830 3 0 ## 2014-05-12 17:00:37.811 6.103 4 0 ## 2014-05-12 17:00:41.427 9.720 5 0 ## UserTime SysTime RealTime BeforeSize AfterSize ## 2014-05-12 17:00:32.868 0.11 0.04 0.02 8192 1400 ## 2014-05-12 17:00:33.178 0.05 0.01 0.02 5496 1672 ## 2014-05-12 17:00:33.677 0.04 0.01 0.01 5768 2557 ## 2014-05-12 17:00:35.538 0.21 0.05 0.04 22528 4907 ## 2014-05-12 17:00:37.811 0.08 0.01 0.02 24576 7072 ## 2014-05-12 17:00:41.427 0.26 0.06 0.04 43008 14336 ## TotalSize Delta ## 2014-05-12 17:00:32.868 9437184 6792 ## 2014-05-12 17:00:33.178 9437184 3824 ## 2014-05-12 17:00:33.677 9437184 3211 ## 2014-05-12 17:00:35.538 9437184 17621 ## 2014-05-12 17:00:37.811 9437184 17504 ## 2014-05-12 17:00:41.427 9437184 28672 Example of Two Benchmark Runs in One Log File The data in the following graph is from a different log file, not the one of primary interest to this article. I’m including this image because it is an example of idle periods followed by busy periods. It would be uninteresting to average the rate of garbage collection over the entire log file period. More interesting would be the rate of garbage collect in the two busy periods. Are they the same or different? Your production data may be similar, for example, bursts when employees return from lunch and idle times on weekend evenings, etc. Once the data is in an R Time Series, you can analyze isolated time windows. Clipping the Time Series data Flashing back to our test case… Viewing the data as a time series is interesting. You can see that the work intensive time period is between 9:00 PM and 3:00 AM. Lets clip the data to the interesting period:     par(mfrow=c(2,1)) plot(g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Complete Log File", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") clipped.g1gc.z=window(g1gc.z, start=as.POSIXct("2014-05-12 21:00:00"), end=as.POSIXct("2014-05-13 03:00:00")) plot(clipped.g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Limited to Benchmark Execution", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") box(which = "outer", lty = "solid") Cumulative Incremental and Full GC count Here is the cumulative incremental and full GC count. When the line is very steep, it indicates that the GCs are repeating very quickly. Notice that the scale on the Y axis is different for full vs. incremental. plot(clipped.g1gc.z[,c(2:3)], main="Cumulative Incremental and Full GC count", xlab="Time of Day", col="#1b9e77") GC Analysis of Benchmark Execution using Time Series data In the following series of 3 graphs: The “After Size” show the amount of heap space in use after each garbage collection. Many Java objects are still referenced, i.e. alive, during each garbage collection. This may indicate that the application has a memory leak, or may indicate that the application has a very large memory footprint. Typically, an application's memory footprint plateau's in the early stage of execution. One would expect this graph to have a flat top. The steep decline in the heap space may indicate that the application crashed after 2:00. The second graph shows that the outliers in real execution time, discussed above, occur near 2:00. when the Java heap seems to be quite full. The third graph shows that Full GCs are infrequent during the first few hours of execution. The rate of Full GC's, (the slope of the cummulative Full GC line), changes near midnight.   plot(clipped.g1gc.z[,c("AfterSize","RealTime","FullCount")], xlab="Time of Day", col=c("#1b9e77","red","#1b9e77")) GC Analysis of heap recovered Each GC trace includes the amount of heap space in use before and after the individual GC event. During garbage coolection, unreferenced objects are identified, the space holding the unreferenced objects is freed, and thus, the difference in before and after usage indicates how much space has been freed. The following box plot and bar chart both demonstrate the same point - the amount of heap space freed per garbage colloection is surprisingly low. par(mfrow=c(2,1)) boxplot(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", horizontal = TRUE, col="red") hist(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", breaks=100, col="red") box(which = "outer", lty = "solid") This graph is the most interesting. The dark blue area shows how much heap is occupied by referenced Java objects. This represents memory that holds live data. The red fringe at the top shows how much data was recovered after each garbage collection. barplot(clipped.g1gc.z[,c("AfterSize","Delta")], col=c("#7570b3","#e7298a"), xlab="Time of Day", border=NA) legend("topleft", c("Live Objects","Heap Recovered on GC"), fill=c("#7570b3","#e7298a")) box(which = "outer", lty = "solid") When I discuss the data in the log files with the customer, I will ask for an explaination for the large amount of referenced data resident in the Java heap. There are two are posibilities: There is a memory leak and the amount of space required to hold referenced objects will continue to grow, limited only by the maximum heap size. After the maximum heap size is reached, the JVM will throw an “Out of Memory” exception every time that the application tries to allocate a new object. If this is the case, the aplication needs to be debugged to identify why old objects are referenced when they are no longer needed. The application has a legitimate requirement to keep a large amount of data in memory. The customer may want to further increase the maximum heap size. Another possible solution would be to partition the application across multiple cluster nodes, where each node has responsibility for managing a unique subset of the data. Conclusion In conclusion, R is a very powerful tool for the analysis of Java garbage collection log files. The primary difficulty is data cleansing so that information can be read into an R data frame. Once the data has been read into R, a rich set of tools may be used for thorough evaluation.

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• Windows 7: How to place SuperFetch cache on an SSD?

  - by Ian Boyd

  I'm thinking of adding a solid state drive (SSD) to my existing Windows 7 installation. I know I can (and should) move my paging file to the SSD: Should the pagefile be placed on SSDs? Yes. Most pagefile operations are small random reads or larger sequential writes, both of which are types of operations that SSDs handle well. In looking at telemetry data from thousands of traces and focusing on pagefile reads and writes, we find that Pagefile.sys reads outnumber pagefile.sys writes by about 40 to 1, Pagefile.sys read sizes are typically quite small, with 67% less than or equal to 4 KB, and 88% less than 16 KB. Pagefile.sys writes are relatively large, with 62% greater than or equal to 128 KB and 45% being exactly 1 MB in size. In fact, given typical pagefile reference patterns and the favorable performance characteristics SSDs have on those patterns, there are few files better than the pagefile to place on an SSD. What I don't know is if I even can put a SuperFetch cache (i.e. ReadyBoost cache) on the solid state drive. I want to get the benefit of Windows being able to cache gigabytes of frequently accessed data on a relativly small (e.g. 30GB) solid state drive. This is exactly what SuperFetch+ReadyBoost (or SuperFetch+ReadyDrive) was designed for. Will Windows offer (or let) me place a ReadyBoost cache on a solid state flash drive connected via SATA? A problem with the ReadyBoost cache over the ReadyDrive cache is that the ReadyBoost cache does not survive between reboots. The cache is encrypted with a per-session key, making its existing contents unusable during boot and SuperFetch pre-fetching during login. Update One I know that Windows Vista limited you to only one ReadyBoost.sfcache file (I do not know if Windows 7 removed that limitation): Q: Can use use multiple devices for EMDs? A: Nope. We've limited Vista to one ReadyBoost per machine Q: Why just one device? A: Time and quality. Since this is the first revision of the feature, we decided to focus on making the single device exceptional, without the difficulties of managing multiple caches. We like the idea, though, and it's under consideration for future versions. I also know that the 4GB limit on the cache file was a limitation of the FAT filesystem used on most USB sticks - an SSD drive would be formatted with NTFS: Q: What's the largest amount of flash that I can use for ReadyBoost? A: You can use up to 4GB of flash for ReadyBoost (which turns out to be 8GB of cache w/ the compression) Q: Why can't I use more than 4GB of flash? A: The FAT32 filesystem limits our ReadyBoost.sfcache file to 4GB Can a ReadyBoost cache on an NTFS volume be larger than 4GB? Update Two The ReadyBoost cache is encrypted with a per-boot session key. This means that the cache has to be re-built after each boot, and cannot be used to help speed boot times, or latency from login to usable. Windows ReadyDrive technology takes advantage of non-volatile (NV) memory (i.e. flash) that is incorporated with some hybrid hard drives. This flash cache can be used to help Windows boot, or resume from hibernate faster. Will Windows 7 use an internal SSD drive as a ReadyBoost/*ReadyDrive*/SuperFetch cache? Is it possible to make Windows store a SuperFetch cache (i.e. ReadyBoost) on a non-removable SSD? Is it possible to not encrypt the ReadyBoost cache, and if so will Windows 7 use the cache at boot time? See also SuperUser.com: ReadyBoost + SSD = ? Windows 7 - ReadyBoost & SSD drives? Support and Q&A for Solid-State Drives Using SDD as a cache for HDD, is there a solution? Performance increase using SSD for paging/fetch/cache or ReadyBoost? (Win7) Windows 7 To Boost SSD Performance How to Disable Nonvolatile Caching

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• How to place SuperFetch cache on an SSD?

  - by Ian Boyd

  I'm thinking of adding a solid state drive (SSD) to my existing Windows 7 installation. I know I can (and should) move my paging file to the SSD: Should the pagefile be placed on SSDs? Yes. Most pagefile operations are small random reads or larger sequential writes, both of which are types of operations that SSDs handle well. In looking at telemetry data from thousands of traces and focusing on pagefile reads and writes, we find that Pagefile.sys reads outnumber pagefile.sys writes by about 40 to 1, Pagefile.sys read sizes are typically quite small, with 67% less than or equal to 4 KB, and 88% less than 16 KB. Pagefile.sys writes are relatively large, with 62% greater than or equal to 128 KB and 45% being exactly 1 MB in size. In fact, given typical pagefile reference patterns and the favorable performance characteristics SSDs have on those patterns, there are few files better than the pagefile to place on an SSD. What I don't know is if I even can put a SuperFetch cache (i.e. ReadyBoost cache) on the solid state drive. I want to get the benefit of Windows being able to cache gigabytes of frequently accessed data on a relativly small (e.g. 30GB) solid state drive. This is exactly what SuperFetch+ReadyBoost (or SuperFetch+ReadyDrive) was designed for. Will Windows offer (or let) me place a ReadyBoost cache on a solid state flash drive connected via SATA? A problem with the ReadyBoost cache over the ReadyDrive cache is that the ReadyBoost cache does not survive between reboots. The cache is encrypted with a per-session key, making its existing contents unusable during boot and SuperFetch pre-fetching during login. Update One I know that Windows Vista limited you to only one ReadyBoost.sfcache file (I do not know if Windows 7 removed that limitation): Q: Can use use multiple devices for EMDs? A: Nope. We've limited Vista to one ReadyBoost per machine Q: Why just one device? A: Time and quality. Since this is the first revision of the feature, we decided to focus on making the single device exceptional, without the difficulties of managing multiple caches. We like the idea, though, and it's under consideration for future versions. I also know that the 4GB limit on the cache file was a limitation of the FAT filesystem used on most USB sticks - an SSD drive would be formatted with NTFS: Q: What's the largest amount of flash that I can use for ReadyBoost? A: You can use up to 4GB of flash for ReadyBoost (which turns out to be 8GB of cache w/ the compression) Q: Why can't I use more than 4GB of flash? A: The FAT32 filesystem limits our ReadyBoost.sfcache file to 4GB Can a ReadyBoost cache on an NTFS volume be larger than 4GB? Update Two The ReadyBoost cache is encrypted with a per-boot session key. This means that the cache has to be re-built after each boot, and cannot be used to help speed boot times, or latency from login to usable. Windows ReadyDrive technology takes advantage of non-volatile (NV) memory (i.e. flash) that is incorporated with some hybrid hard drives. This flash cache can be used to help Windows boot, or resume from hibernate faster. Will Windows 7 use an internal SSD drive as a ReadyBoost/*ReadyDrive*/SuperFetch cache? Is it possible to make Windows store a SuperFetch cache (i.e. ReadyBoost) on a non-removable SSD? Is it possible to not encrypt the ReadyBoost cache, and if so will Windows 7 use the cache at boot time? See also SuperUser.com: ReadyBoost + SSD = ? Windows 7 - ReadyBoost & SSD drives? Support and Q&A for Solid-State Drives Using SDD as a cache for HDD, is there a solution? Performance increase using SSD for paging/fetch/cache or ReadyBoost? (Win7) Windows 7 To Boost SSD Performance How to Disable Nonvolatile Caching

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• Hard drive after PCB swap strange stuff

  - by ramyy

  I’ve done a PCB swap to my HDD. The HDD model is: WD6400AAKS-00A7B2. The original PCB PN matches the new one (first three letter groups), though the cache mismatches (16MB original, 8MB new). The Hardware store that made the swap told me it was hard to do the swap, they have done firmware adaptation. I can see that this firmware version does not match the original, (01.03B01 original, 05.04E05 new). Still I can see that the serial number and model of the drive is correct, the hard drive appeared normal in the BIOS, all the partitions show and everything appears normal. I have encountered three things though, I have left the drive non operated for 2-3 weeks after the swap to avoid corrupting the data or anything else the new PCB might cause, until I buy a new drive and backup the data. I got a drive, and when I powered the old drive manually (I have a laptop, I use a normal desktop power supply and a USB/SATA connector), I heard the motor start and I could hear ticking as if the motor’s somehow struggling to start, and then the motor sound starts again then the ticking, and so on.. I tried powering again it happened again. The third time it started normally and I could see everything normally. I took the chance and copied all the data over to the new drive. When I was done, I powered off the drive (after more than 25 hours of continuous operation), tried to power it up again and it did so normally, and so are the times I powered it up later; but I got very suspicious now. What could be the problem here? And what happened new, it used to power normally after the swap directly? The second thing that happened is that I found size differences with some files; some include movies, songs, (.iso) files for games, and programs. I could find the size is the same, but size on disk is a little more on the new drive for these files. . I’ve tried some of those files (with size differences) they worked fine. They are not too much but still make you suspicious of the integrity of the data copied; one cannot try if all files are working for about (580 GB) worth of data. I tried copying these files on the same partition they exist of the old drive; they are the same in size as when copied to the new drive (allocation unit size not the issue). I took an image of a partition (sector by sector including empty ones) and when I explore it, these file sizes are equal to the original (old drive); I copy them anywhere else their size on disk, increases, i.e becomes equal to the ones I copy from the old drive itself anywhere. Why the size difference and can one trust the integrity of the data?? The third thing is that when I connect my new external USB HDD, the partitions of the old HDD unmount and then mount again. Connected are: (USB mouse + Old HDD) then external HDD. Why that happens?? Considering the following: I compared the SMART reports from after the swap directly and after the copying, no error readings or reallocated sectors where reported. Here they are: http://www.image-share.com/ijpg-1939-219.html I later ran both WD data life guard tests and they came out passed. I’m worried for this drive since I must be sure the data is fine and safe on the new one, and I will consider it backup for the new one, since you can’t trust anything anymore. I hope you can forgive me for the length of the post, but couldn’t ignore any of the details, this hard drive contains very important data to me and I have to deal with the situation with great care.

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• Code Contracts: Hiding ContractException

  - by DigiMortal

  It’s time to move on and improve my randomizer I wrote for an example of static checking of code contracts. In this posting I will modify contracts and give some explanations about pre-conditions and post-conditions. Also I will show you how to avoid ContractExceptions and how to replace them with your own exceptions. As a first thing let’s take a look at my randomizer. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } We have some problems here. We need contract for method output and we also need some better exception handling mechanism. As ContractException as type is hidden from us we have to switch from ContractException to some other Exception type that we can catch. Adding post-condition Pre-conditions are contracts for method’s input interface. Read it as follows: pre-conditions make sure that all conditions for method’s successful run are met. Post-conditions are contracts for output interface of method. So, post-conditions are for output arguments and return value. My code misses the post-condition that checks return value. Return value in this case must be greater or equal to minimum value and less or equal to maximum value. To make sure that method can run only the correct value I added call to Contract.Ensures() method. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } I think that the line I added does not need any further comments. Avoiding ContractException for input interface ContractException lives in hidden namespace and we cannot see it at design time. But it is common exception type for all contract exceptions that we do not switch over to some other type. The case of Contract.Requires() method is simple: we can tell it what kind of exception we need if something goes wrong with contract it ensures. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires<ArgumentOutOfRangeException>(         min < max,         "Min must be less than max"     );       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } Now, if we violate the input interface contract giving min value that is not less than max value we get ArgumentOutOfRangeException. Avoiding ContractException for output interface Output interface is more complex to control. We cannot give exception type there and hope that this type of exception will be thrown if something goes wrong. Instead we have to use delegate that gathers information about problem and throws the exception we expect to be thrown. From documentation you can find the following example about the delegate I mentioned. Contract.ContractFailed += (sender, e) => {     e.SetHandled();     e.SetUnwind(); // cause code to abort after event     Assert.Fail(e.FailureKind.ToString() + ":" + e.DebugMessage); }; We can use this delegate to throw the Exception. Let’s move the code to separate method too. Here is our method that uses now ContractException hiding. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );     Contract.ContractFailed += Contract_ContractFailed;       var rnd = new Random();     return rnd.Next(min, max)+1000; } And here is the delegate that creates exception. public static void Contract_ContractFailed(object sender,     ContractFailedEventArgs e) {     e.SetHandled();     e.SetUnwind();       throw new Exception(e.FailureKind.ToString() + ":" + e.Message); } Basically we can do in this delegate whatever we like to do with output interface errors. We can even introduce our own contract exception type. As you can see later then ContractFailed event is very useful at unit testing.

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• Do I need to store a generic rotation point/radius for rotating around a point other than the origin for object transforms?

  - by Casey

  I'm having trouble implementing a non-origin point rotation. I have a class Transform that stores each component separately in three 3D vectors for position, scale, and rotation. This is fine for local rotations based on the center of the object. The issue is how do I determine/concatenate non-origin rotations in addition to origin rotations. Normally this would be achieved as a Transform-Rotate-Transform for the center rotation followed by a Transform-Rotate-Transform for the non-origin point. The problem is because I am storing the individual components, the final Transform matrix is not calculated until needed by using the individual components to fill an appropriate Matrix. (See GetLocalTransform()) Do I need to store an additional rotation (and radius) for world rotations as well or is there a method of implementation that works while only using the single rotation value? Transform.h #ifndef A2DE_CTRANSFORM_H #define A2DE_CTRANSFORM_H #include "../a2de_vals.h" #include "CMatrix4x4.h" #include "CVector3D.h" #include <vector> A2DE_BEGIN class Transform { public: Transform(); Transform(Transform* parent); Transform(const Transform& other); Transform& operator=(const Transform& rhs); virtual ~Transform(); void SetParent(Transform* parent); void AddChild(Transform* child); void RemoveChild(Transform* child); Transform* FirstChild(); Transform* LastChild(); Transform* NextChild(); Transform* PreviousChild(); Transform* GetChild(std::size_t index); std::size_t GetChildCount() const; std::size_t GetChildCount(); void SetPosition(const a2de::Vector3D& position); const a2de::Vector3D& GetPosition() const; a2de::Vector3D& GetPosition(); void SetRotation(const a2de::Vector3D& rotation); const a2de::Vector3D& GetRotation() const; a2de::Vector3D& GetRotation(); void SetScale(const a2de::Vector3D& scale); const a2de::Vector3D& GetScale() const; a2de::Vector3D& GetScale(); a2de::Matrix4x4 GetLocalTransform() const; a2de::Matrix4x4 GetLocalTransform(); protected: private: a2de::Vector3D _position; a2de::Vector3D _scale; a2de::Vector3D _rotation; std::size_t _curChildIndex; Transform* _parent; std::vector<Transform*> _children; }; A2DE_END #endif Transform.cpp #include "CTransform.h" #include "CVector2D.h" #include "CVector4D.h" A2DE_BEGIN Transform::Transform() : _position(), _scale(1.0, 1.0), _rotation(), _curChildIndex(0), _parent(nullptr), _children() { /* DO NOTHING */ } Transform::Transform(Transform* parent) : _position(), _scale(1.0, 1.0), _rotation(), _curChildIndex(0), _parent(parent), _children() { /* DO NOTHING */ } Transform::Transform(const Transform& other) : _position(other._position), _scale(other._scale), _rotation(other._rotation), _curChildIndex(0), _parent(other._parent), _children(other._children) { /* DO NOTHING */ } Transform& Transform::operator=(const Transform& rhs) { if(this == &rhs) return *this; this->_position = rhs._position; this->_scale = rhs._scale; this->_rotation = rhs._rotation; this->_curChildIndex = 0; this->_parent = rhs._parent; this->_children = rhs._children; return *this; } Transform::~Transform() { _children.clear(); _parent = nullptr; } void Transform::SetParent(Transform* parent) { _parent = parent; } void Transform::AddChild(Transform* child) { if(child == nullptr) return; _children.push_back(child); } void Transform::RemoveChild(Transform* child) { if(_children.empty()) return; _children.erase(std::remove(_children.begin(), _children.end(), child), _children.end()); } Transform* Transform::FirstChild() { if(_children.empty()) return nullptr; return *(_children.begin()); } Transform* Transform::LastChild() { if(_children.empty()) return nullptr; return *(_children.end()); } Transform* Transform::NextChild() { if(_children.empty()) return nullptr; std::size_t s(_children.size()); if(_curChildIndex >= s) { _curChildIndex = s; return nullptr; } return _children[_curChildIndex++]; } Transform* Transform::PreviousChild() { if(_children.empty()) return nullptr; if(_curChildIndex == 0) { return nullptr; } return _children[_curChildIndex--]; } Transform* Transform::GetChild(std::size_t index) { if(_children.empty()) return nullptr; if(index > _children.size()) return nullptr; return _children[index]; } std::size_t Transform::GetChildCount() const { if(_children.empty()) return 0; return _children.size(); } std::size_t Transform::GetChildCount() { return static_cast<const Transform&>(*this).GetChildCount(); } void Transform::SetPosition(const a2de::Vector3D& position) { _position = position; } const a2de::Vector3D& Transform::GetPosition() const { return _position; } a2de::Vector3D& Transform::GetPosition() { return const_cast<a2de::Vector3D&>(static_cast<const Transform&>(*this).GetPosition()); } void Transform::SetRotation(const a2de::Vector3D& rotation) { _rotation = rotation; } const a2de::Vector3D& Transform::GetRotation() const { return _rotation; } a2de::Vector3D& Transform::GetRotation() { return const_cast<a2de::Vector3D&>(static_cast<const Transform&>(*this).GetRotation()); } void Transform::SetScale(const a2de::Vector3D& scale) { _scale = scale; } const a2de::Vector3D& Transform::GetScale() const { return _scale; } a2de::Vector3D& Transform::GetScale() { return const_cast<a2de::Vector3D&>(static_cast<const Transform&>(*this).GetScale()); } a2de::Matrix4x4 Transform::GetLocalTransform() const { Matrix4x4 p((_parent ? _parent->GetLocalTransform() : a2de::Matrix4x4::GetIdentity())); Matrix4x4 t(a2de::Matrix4x4::GetTranslationMatrix(_position)); Matrix4x4 r(a2de::Matrix4x4::GetRotationMatrix(_rotation)); Matrix4x4 s(a2de::Matrix4x4::GetScaleMatrix(_scale)); return (p * t * r * s); } a2de::Matrix4x4 Transform::GetLocalTransform() { return static_cast<const Transform&>(*this).GetLocalTransform(); } A2DE_END

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• PostSharp, Obfuscation, and IL

  - by Simon Cooper

  Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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• Expectations + Rewards = Innovation

  - by D'Arcy Lussier

  “Innovation” is a heavy word. We regard those that embrace it as “Innovators”. We describe organizations as being “Innovative”. We hold those associated with the word in high regard, even though its dictionary definition is very simple: Introducing something new. What our culture has done is wrapped Innovation in white robes and a gold crown. Innovation is rarely just introducing something new. Innovations and innovators are typically associated with other terms: groundbreaking, genius, industry-changing, creative, leading. Being a true innovator and creating innovations are a big deal, and something companies try to strive for…or at least say they strive for. There’s huge value in being recognized as an innovator in an industry, since the idea is that innovation equates to increased profitability. IBM ran an ad a few years back that showed what their view of innovation is: “The point of innovation is to make actual money.” If the money aspect makes you feel uneasy, consider it another way: the point of innovation is to <insert payoff here>. Companies that innovate will be more successful. Non-profits that innovate can better serve their target clients. Governments that innovate can better provide services to their citizens. True innovation is not easy to come by though. As with anything in business, how well an organization will innovate is reliant on the employees it retains, the expectations placed on those employees, and the rewards available to them. In a previous blog post I talked about one formula: Right Employees + Happy Employees = Productive Employees I want to introduce a new one, that builds upon the previous one: Expectations + Rewards = Innovation  The level of innovation your organization will realize is directly associated with the expectations you place on your staff and the rewards you make available to them. Expectations We may feel uncomfortable with the idea of placing expectations on our staff, mainly because expectation has somewhat of a negative or cold connotation to it: “I expect you to act this way or else!” The problem is in the or-else part…we focus on the negative aspects of failing to meet expectations instead of looking at the positive side. “I expect you to act this way because it will produce <insert benefit here>”. Expectations should not be set to punish but instead be set to ensure quality. At a recent conference I spoke with some Microsoft employees who told me that you have five years from starting with the company to reach a “Senior” level. If you don’t, then you’re let go. The expectation Microsoft placed on their staff is that they should be working towards improving themselves, taking more responsibility, and thus ensure that there is a constant level of quality in the workforce. Rewards Let me be clear: a paycheck is not a reward. A paycheck is simply the employer’s responsibility in the employee/employer relationship. A paycheck will never be the key motivator to drive innovation. Offering employees something over and above their required compensation can spur them to greater performance and achievement. Working in the food service industry, this tactic was used again and again: whoever has the highest sales over lunch will receive a free lunch/gift certificate/entry into a draw/etc. There was something to strive for, to try beyond the baseline of what our serving jobs were. It was through this that innovative sales techniques would be tried and honed, with key servers being top sellers time and time again. At a code camp I spoke at, I was amazed to see that all the employees from one company receive $100 Visa gift cards as a thank you for taking time to speak. Again, offering something over and above that can give that extra push for employees. Rewards work. But what about the fairness angle? In the restaurant example I gave, there were servers that would never win the competition. They just weren’t good enough at selling and never seemed to get better. So should those that did work at performing better and produce more sales for the restaurant not get rewarded because those who weren’t working at performing better might get upset? Of course not! Organizations succeed because of their top performers and those that strive to join their ranks. The Expectation/Reward Graph While the Expectations + Rewards = Innovation formula may seem like a simple mathematics formula, there’s much more going under the hood. In fact there are three different outcomes that could occur based on what you put in as values for Expectations and Rewards. Consider the graph below and the descriptions that follow: Disgruntled – High Expectation, Low Reward I worked at a company where the mantra was “Company First, Because We Pay You”. Even today I still hear stories of how this sentiment continues to be perpetuated: They provide you a paycheck and a means to live, therefore you should always put them as your top priority. Of course, this is a huge imbalance in the expectation/reward equation. Why would anyone willingly meet high expectations of availability, workload, deadlines, etc. when there is no reward other than a paycheck to show for it? Remember: paychecks are not rewards! Instead, you see employees be disgruntled which not only affects the level of production but also the level of quality within an organization. It also means that you see higher turnover. Complacent – Low Expectation, Low Reward Complacency is a systemic problem that typically exists throughout all levels of an organization. With no real expectations or rewards, nobody needs to excel. In fact, those that do try to innovate, improve, or introduce new things into the organization might be shunned or pushed out by the rest of the staff who are just doing things the same way they’ve always done it. The bigger issue for the organization with low/low values is that at best they’ll never grow beyond their current size (and may shrink actually), and at worst will cease to exist. Entitled – Low Expectation, High Reward It’s one thing to say you have the best people and reward them as such, but its another thing to actually have the best people and reward them as such. Organizations with Entitled employees are the former: their organization provides them with all types of comforts, benefits, and perks. But there’s no requirement before the rewards are dolled out, and there’s no short-list of who receives the rewards. Everyone in the company is treated the same and is given equal share of the spoils. Entitlement is actually almost identical with Complacency with one notable difference: just try to introduce higher expectations into an entitled organization! Entitled employees have been spoiled for so long that they can’t fathom having rewards taken from them, or having to achieve specific levels of performance before attaining them. Those running the organization also buy in to the Entitled sentiment, feeling that they must persist the same level of comforts to appease their staff…even though the quality of the employee pool may be suspect. Innovative – High Expectation, High Reward Finally we have the Innovative organization which places high expectations but also provides high rewards. This organization gets it: if you truly want the best employees you need to apply equal doses of pressure and praise. Realize that I’m not suggesting crazy overtime or un-realistic working conditions. I do not agree with the “Glengary-Glenross” method of encouragement. But as anyone who follows sports can tell you, the teams that win are the ones where the coaches push their players to be their best; to achieve new levels of performance that they didn’t know they could receive. And the result for the players is more money, fame, and opportunity. It’s in this environment that organizations can focus on innovation – true innovation that builds the business and allows everyone involved to truly benefit. In Closing Organizations love to use the word “Innovation” and its derivatives, but very few actually do innovate. For many, the term has just become another marketing buzzword to lump in with all the other business terms that get overused. But for those organizations that truly get the value of innovation, they will be the ones surging forward while other companies simply fade into the background. And they will be the organizations that expect more from their employees, and give them their just rewards.

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• PostSharp, Obfuscation, and IL

  - by Simon Cooper

  Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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• Sorting a Linked List [closed]

  - by Mohit Sehgal

  I want to sort a linked list. Here Node is class representing a node in a Linked List I have written a code to bubble sort a linked list. Program does not finishes execution. Kindly point out the mistakes. class Node { public: int data; public: Node *next; Node() { data=0;next=0; } Node(int d) { data=d; } void setData(int d) { data=d; } void print() { cout<<data<<endl; } bool operator==(Node n) { return this->data==n.data; } bool operator >(Node d) { if((this->data) > (d.data)) return true; return false; } }; class LList { public: int noOfNodes; Node *start;/*Header Node*/ LList() { start=new Node; noOfNodes=0;start=0; } void addAtFront(Node* n) { n->next=(start); start=n; noOfNodes++; } void addAtLast(Node* n) { Node *cur=(start); n->next=NULL; if(start==NULL) { start=n; noOfNodes++; return; } while(cur->next!=NULL) { cur=cur->next; } cur->next=n; noOfNodes++; } void addAtPos(Node *n,int pos) { if(pos==1) { addAtFront(n);return; } Node *cur=(start); Node *prev=NULL; int curPos=0; n->next=NULL; while(cur!=NULL) { curPos++; if(pos==curPos+1) { prev=cur; } if(pos==curPos) { n->next=cur; prev->next=n; break; } cur=cur->next; } noOfNodes++; } void removeFirst() { Node *del=start; start=start->next; delete del; noOfNodes--; return; } void removeLast() { Node *cur=start,*prev=NULL; while(cur->next!=NULL) { prev=cur; cur=cur->next; } prev->next=NULL; Node *del=cur->next; delete del; noOfNodes--; return; } void removeNodeAt(int pos) { if(pos<1) return; if(pos==1) { removeFirst();return;} int curPos=1; Node* cur=start->next; Node* prev=start; Node* del=NULL; while(curPos<pos&&cur!=NULL) { curPos++; if(curPos==pos) { del=cur; prev->next=cur->next; cur->next=NULL; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } void removeNode(Node *d) { Node *cur=start; if(*d==*cur) { removeFirst();return; } cur=start->next; Node *prev=start,*del=NULL; while(cur!=NULL) { if(*cur==*d) { del=cur; prev->next=cur->next; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } int getPosition(Node data) { int pos=0; Node *cur=(start); while(cur!=NULL) { pos++; if(*cur==data) { return pos; } cur=cur->next; } return -1;//not found } Node getNode(int pos) { if(pos<1) return -1;// not a valid position else if(pos>noOfNodes) return -1; // not a valid position Node *cur=(start); int curPos=0; while(cur!=NULL) { if(++curPos==pos) return *cur; cur=cur->next; } } void reverseList()//reverse the list { Node* cur=start->next; Node* d=NULL; Node* prev=start; while(cur!=NULL) { d=cur->next; cur->next=start; start=cur; prev->next=d; cur=d; } } void sortBubble() { Node *i=start,*j=start,*prev=NULL,*temp=NULL,*after=NULL; int count=noOfNodes-1;int icount=0; while(i->next!=NULL) { j=start; after=j->next; icount=0; while(++icount!=count) { if((*j)>(*after)) { temp=after->next; after->next=j; prev->next=j->next; j->next=temp; prev=after; after=j->next; } else{ prev=j; j=after; after=after->next; } } i=i->next; count--; } } void traverse() { Node *cur=(start); int c=0; while(cur!=NULL) { // cout<<"start"<<start; c++; cur->print(); cur=cur->next; } noOfNodes=c; } ~LList() { delete start; } }; int main() { int n; cin>>n; int d; LList list; Node *node; Node *temp=new Node(2123); for(int i=0;i<n;i++) { cin>>d; node=new Node(d); list.addAtLast(node); } list.addAtPos(temp,1); cout<<"traverse\n"; list.traverse(); temp=new Node(12); list.removeNode(temp); cout<<"12 removed"; list.traverse(); list.reverseList(); cout<<"\nreversed\n"; list.traverse(); cout<<"bubble sort\n"; list.sortBubble(); list.traverse(); getch(); delete node; return 0; }

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