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• ORA-4030 Troubleshooting

  - by [email protected]

  QUICKLINK: Note 399497.1 FAQ ORA-4030 Note 1088087.1 : ORA-4030 Diagnostic Tools [Video]   Have you observed an ORA-0430 error reported in your alert log? ORA-4030 errors are raised when memory or resources are requested from the Operating System and the Operating System is unable to provide the memory or resources.   The arguments included with the ORA-4030 are often important to narrowing down the problem. For more specifics on the ORA-4030 error and scenarios that lead to this problem, see Note 399497.1 FAQ ORA-4030.   Looking for the best way to diagnose? There are several available diagnostic tools (error tracing, 11g Diagnosibility, OCM, Process Memory Guides, RDA, OSW, diagnostic scripts) that collectively can prove powerful for identifying the cause of the ORA-4030.    Error Tracing   The ORA-4030 error usually occurs on the client workstation and for this reason, a trace file and alert log entry may not have been generated on the server side.  It may be necessary to add additional tracing events to get initial diagnostics on the problem. To setup tracing to trap the ORA-4030, on the server use the following in SQLPlus: alter system set events '4030 trace name heapdump level 536870917;name errorstack level 3';Once the error reoccurs with the event set, you can turn off  tracing using the following command in SQLPlus:alter system set events '4030 trace name context off; name context off';NOTE:   See more diagnostics information to collect in Note 399497.1  11g DiagnosibilityStarting with Oracle Database 11g Release 1, the Diagnosability infrastructure was introduced which places traces and core files into a location controlled by the DIAGNOSTIC_DEST initialization parameter when an incident, such as an ORA-4030 occurs.  For earlier versions, the trace file will be written to either USER_DUMP_DEST (if the error was caught in a user process) or BACKGROUND_DUMP_DEST (if the error was caught in a background process like PMON or SMON). The trace file may contain vital information about what led to the error condition.    Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Informationto Support[Video]  Oracle Configuration Manager (OCM) Oracle Configuration Manager (OCM) works with My Oracle Support to enable proactive support capability that helps you organize, collect and manage your Oracle configurations. Oracle Configuration Manager Quick Start Guide Note 548815.1: My Oracle Support Configuration Management FAQ Note 250434.1: BULLETIN: Learn More About My Oracle Support Configuration Manager    General Process Memory Guides   An ORA-4030 indicates a limit has been reached with respect to the Oracle process private memory allocation.    Each Operating System will handle memory allocations with Oracle slightly differently. Solaris     Note 163763.1Linux       Note 341782.1IBM AIX   Notes 166491.1 and 123754.1HP           Note 166490.1Windows Note 225349.1, Note 373602.1, Note 231159.1, Note 269495.1, Note 762031.1Generic    Note 169706.1   RDAThe RDA report will show more detailed information about the database and Server Configuration. Note 414966.1 RDA Documentation Index Download RDA -- refer to Note 314422.1 Remote Diagnostic Agent (RDA) 4 - Getting Started OS Watcher (OSW)This tool is designed to gather Operating System side statistics to compare with the findings from the database.  This is a key tool in cases where memory usage is higher than expected on the server while not experiencing ORA-4030 errors currently. Reference more details on setup and usage in Note 301137.1 OS Watcher User Guide Diagnostic Scripts   Refer to Note 1088087.1 : ORA-4030 Diagnostic Tools [Video] Common Causes/Solutions The ORA-4030 can occur for a variety of reasons.  Some common causes are:   * OS Memory limit reached such as physical memory and/or swap/virtual paging.   For instance, IBM AIX can experience ORA-4030 issues related to swap scenarios.  See Note 740603.1 10.2.0.4 not using large pages on AIX for more on that problem. Also reference Note 188149.1 for pointers on 10g and stack size issues.* OS limits reached (kernel or user shell limits) that limit overall, user level or process level memory * OS limit on PGA memory size due to SGA attach address           Reference: Note 1028623.6 SOLARIS How to Relocate the SGA* Oracle internal limit on functionality like PL/SQL varrays or bulk collections. ORA-4030 errors will include arguments like "pl/sql vc2" "pmucalm coll" "pmuccst: adt/re".  See Coding Pointers for pointers on application design to get around these issues* Application design causing limits to be reached* Bug - space leaks, heap leaks   ***For reference to the content in this blog, refer to Note.1088267.1 Master Note for Diagnosing ORA-4030

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• Site Speed - 5 Quick Reasons You Need Speed

  Google have introduced a new ranking factor called 'site speed' into their search algorithm. From now on, the length of time it takes for your web pages to load will influence your search engine positioning on Google.com. In other words fast websites will be favored over slow websites in its search results.

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• readonly keyword

  - by nmarun

  This is something new that I learned about the readonly keyword. Have a look at the following class: 1: public class MyClass 2: { 3: public string Name { get; set; } 4: public int Age { get; set; } 5:  6: private readonly double Delta; 7:  8: public MyClass() 9: { 10: Initializer(); 11: } 12:  13: public MyClass(string name = "", int age = 0) 14: { 15: Name = name; 16: Age = age; 17: Initializer(); 18: } 19:  20: private void Initializer() 21: { 22: Delta = 0.2; 23: } 24: } I have a couple of public properties and a private readonly member. There are two constructors – one that doesn’t take any parameters and the other takes two parameters to initialize the public properties. I’m also calling the Initializer method in both constructors to initialize the readonly member. Now when I build this, the code breaks and the Error window says: “A readonly field cannot be assigned to (except in a constructor or a variable initializer)” Two things after I read this message: It’s such a negative statement. I’d prefer something like: “A readonly field can be assigned to (or initialized) only in a constructor or through a variable initializer” But in my defense, I AM assigning it in a constructor (only indirectly). All I’m doing is creating a method that does it and calling it in a constructor. Turns out, .net was not ‘frameworked’ this way. We need to have the member initialized directly in the constructor. If you have multiple constructors, you can just use the ‘this’ keyword on all except the default constructors to call the default constructor. This default constructor can then initialize your readonly members. This will ensure you’re not repeating the code in multiple places. A snippet of what I’m talking can be seen below: 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha; 10: private readonly int Beta; 11: private readonly double Delta; 12: private readonly double Gamma; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: } 26: } See the syntax in line 22 and you’ll know what I’m talking about. So the default constructor gets called before the one in line 22. These are known as constructor initializers and they allow one constructor to call another. The other ‘myth’ I had about readonly members is that you can set it’s value only once. This was busted as well (I recall Adam and Jamie’s show). Say you’ve initialized the readonly member through a variable initializer. You can over-write this value in any of the constructors any number of times. 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha = "asdf"; 10: private readonly int Beta = 15; 11: private readonly double Delta = 0.077; 12: private readonly double Gamma = 1.0; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: Beta = 3; 26: } 27:  28: public Person(string name, DateTime dob) : this() 29: { 30: Name = name; 31: DateOfBirth = dob; 32:  33: Alpha = ";LKJ"; 34: Gamma = 0.0898; 35: } 36:  37: public Person(int uniqueNumber, string name, int age, DateTime dob, string invoiceNumber) : this() 38: { 39: UniqueNumber = uniqueNumber; 40: Name = name; 41: Age = age; 42: DateOfBirth = dob; 43: InvoiceNumber = invoiceNumber; 44:  45: Alpha = "QWER"; 46: Beta = 5; 47: Delta = 1.0; 48: Gamma = 0.0; 49: } 50: } In the above example, every constructor over-writes the values for the readonly members. This is perfectly valid. There is a possibility that based on the way the object is instantiated, the readonly member will have a different value. Well, that’s all I have for today and read this as it’s on a related topic.

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• design of 'game engine' for small javascript games?

  - by Matt Ball

  I'm making a group of two or three simple javascript games for fun. After someone finishes one game, they'll be presented with a harder or easier version of another game depending on whether the original game was won or lost. I have a high-level question about the design of things: So far I've created a class for one game type that manages the interaction with the UI and the state of the game itself. But for tracking how many of the subgames have been won, or for understanding whether the next game presented should be more or less difficult, are there arguments to be made for making a 'game engine' class? How does the engine communicate to the games? For instance, when a game is won, how is that information relayed to the engine? Is there a better or more common design? (If you want to see what I have so far, the games are slowly taking shape here: https://github.com/yosemitebandit/candela and can be viewed at http://yosemitebandit.com/candela)

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• SQL Developer Debugging, Watches, Smart Data, & Data

  - by thatjeffsmith

  After presenting the SQL Developer PL/SQL debugger for about an hour yesterday at KScope12 in San Antonio, my boss came up and asked, “Now, would you really want to know what the Smart Data panel does?” Apparently I had ‘made up’ my own story about what that panel’s intent is based on my experience with it. Not good Jeff, not good. It was a very small point of my presentation, but I probably should have read the docs. The Smart Data tab displays information about variables, using your Debugger: Smart Data preferences. You can also specify these preferences by right-clicking in the Smart Data window and selecting Preferences. Debugger Smart Data Preferences, control number of variables to display The Smart Data panel auto-inspects the last X accessed variables. So if you have a program with 26 variables, instead of showing you all 26, it will just show you the last two variables that were referenced in your program. If you were to click on the ‘Data’ debug panel, you’ll see EVERYTHING. And if you only want to see a very specific set of values, then you should use Watches. The Smart Data Panel As I step through the code, the variables being tracked change as they are referenced. Only the most recent ones display. This is controlled by the ‘Maximum Locations to Remember’ preference. Step through the code, see the latest variables accessed The Data Panel All variables are displayed. Might be information overload on large PL/SQL programs where you have many dozens or even hundreds of variables to track. Shows everything all the time Watches Watches are added manually and only show what you ask for. Data on Demand – add a watch to track a specific variable Remember, you can interact with your data If you want to do more than just watch, you can mouse-right on a data element, and change the value of the variable as the program is running. This is one of the primary benefits to debugging over using DBMS_OUTPUT to track what’s happening in your program. Change the values while the program is running to test your ‘What if?’ scenarios

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• Quote of the Day: Dissenting Opinions

  - by BuckWoody

  Seems in our current climate the only thing we can’t tolerate is someone else’s thoughts. The sides of the arguments we hear are those that are the most shrill. In that environment, you’ll notice there are some people in the back that don’t speak up – but are troubled by the discord. Those may be the people you really want to hear from. “It is the man who does not want to express an opinion whose opinion I want.“ - Abraham Lincoln Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Team Foundation Server – How to pass ReferencePath argument to MSBuild

  - by Gopinath

  When we manually build a .NET project using Visual Studio, the reference paths set in Project Properties are picked up by Visual Studio for referring to dependent DLLs. But the project is built using TFS, the reference path’s specified in project properties are not considered. This is because Reference Paths are user specific settings and they are not stored in .proj files(they are stored in user settings files). The TFS build may break if it does not find the required DLLs in GAC. We can solve the problem by passing ReferencePath parameter to MSBuild in TFS build configurations. Go to Team Explorer Select Build Defintion >> Edit Build Definition Switch to Process tab Navigate to Advanced Section and locate MSBuild Arguments Add the following: /p:ReferencePath=”{File path}”

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• Eliminate delay between looping XNA songs?

  - by Stephane Beniak

  I'm making a game with XNA and trying to get some background music to loop correctly. Because the file is an MP3 of about 30 seconds in length, I instantiated it as a Song. I want it to loop perfectly, but even when I set the MediaPlayer.IsRepeating property to true, there is always a delay of about one second before the song starts up again. Is there any way to eliminate this delay such that the song loops instantly, so it can play more fluently?

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• Customized Database Listener Names Now Supported for EBS

  - by sreelatha.mahendra(at)oracle.com

  The database listener name can now be configured using AutoConfig with newly introduced context variable s_db_listener. Prior to this certification it was not possible to use AutoConfig generated listener.ora files for managing listeners from SRVCTL when there were multiple RAC instances on the same server.To use this feature E-Business Suite customers need to apply the following patch:11.5.10CU2 - Roll Up Patch 9535311 (RUP-U) or higher12.0.x - R12.TXK.A.delta.7 or higher 12.1.x - R12.TXK.B.delta 3 or higher

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• Programming Test

  - by Travis Webb

  We are looking to hire some more Java developers onto our team, and plan to test their coding abilities with a test. We currently use a web-based Java test that automatically compiles and runs the code, but it is very flaky and we're having problems with our candidates losing their work on this site. Not only is this frustrating for everyone, it makes us look like we don't know what we're doing. Is there a popular testing suite out there? What do you use? I'm not interested in dogmatic arguments on whether or not I should be testing my candidates in this way, I'm looking for a tool that will help me do it.

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• Use of Business Parameters in BPM12c

  - by Abhishek Mittal-Oracle

  With the release of BPM12c, a new feature to use Business Parameters is introduced through which we can define a business parameter which will behave as a global variable which can be used within BPM project. Business Administrator can be the one responsible to modify the business parameters value dynamically at run-time which may bring change in BPM process flow where it is used.This feature was a part of BPM10g product and was extensively used. In BPM11g, this feature is not present currently.Business Parameters can be defined in 2 ways:1. Using Jdev to define business parameters, and 2. Using BPM workspace to define business parameters.It is important to note that business parameters need to be mapped with a valid organisation unit defined in a BPM project. If the same is not handled, exceptions like 'BPM-70702' will be thrown by BPM Engine. This is because business parameters work along with organisation defined in a BPM project.At the same time, we can use same business parameter across different organisation units with different values. Business Parameters in BPM12c has this capability to handle multiple values with different organisation units defined in a single BPM project. This enables business to re-use same business parameters defined in a BPM project across different organisations.Business parameters can be defined using the below data types:1. int2. string 3. boolean4. double While defining an business parameter, it is mandatory to provide a default value. Below are the steps to define a business parameter in Jdev: Step 1:  Open 'Organization' and click on 'Business Parameters' tab.Step 2:  Click on '+' button.Step 3: Add business parameter name, type and provide default value(mandatory).Step 4: Click on 'OK' button.Step 5: Business parameter is defined. Below are the steps to define a business parameter in BPM workspace: Step 1: Login to BPM workspace using admin-username and password.Step 2: Click on 'Administration' on the right top side of workspace.Step 3: Click on 'Business Parameters' in the left navigation panel under 'Organization'. Step 4:  Click on '+' button.Step 5: Add business parameter name, type and provide default value(mandatory).Step 6: Click on 'OK' button.Step 7: Business parameter is defined. Note: As told earlier in the blog, it is necessary to define and map a valid organization ID with predefined variable 'organizationalUnit' under data associations in an BPM process before the business parameter is used. I have created one sample PoC demonstrating the use of Business Parameters in BPM12c and it can be found here.

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• As a game developer, which data structure use for develop the game? [duplicate]

  - by Rizwanabbasi

  This question already has an answer here: When should vector/list be used? 5 answers We are developing a game for bank robbery. The game plots a bank robbery. Lots of people witness that robbery. Our game will load the lists of suspected offenders while the players (witnesses) will have to identify the offenders of this robbery. Game should load list of offenders to identify the one as quickly as possible. Admin can add/remove offenders in the lists and two or more lists of offenders can also be merged into one (to show it to the player). As a game developer, which data structure we should use for develop the game? Justify your selection with solid arguments. Remember the most critical requirement is that the list should load super fast.

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• Cocos2dx InApp Purchase for ios

  - by Ahmad dar

  I am trying to integrate In App Purchases in my app made by using cocos2d x c++. I am using easyNdk Helper for In App Purchases. My In App Purchases works perfectly for my Objective C apps. But for cocos2d x it is throwing error for the following line if ([[RageIAPHelper sharedInstance] productPurchased:productP.productIdentifier]) Actually value came from CPP file perfectly in form of arguments and Properly shows their value in NSLog , But it always shows the objects as nil even objetcs print their stored value in NSLog also @try catch condition is not working and finally throw the following error Please Help me what i have to do ? Thanks

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• how to send trackback and pingback using c# script

  - by anirudha

  This is a very interesting topic because if you want to search about them. you find much useless stuff even you use c# as prefix. 1. how trackback works ? Every blog who have support to trackback that in their every post they have some text comment like <rdf:/rdf></rdf:rdf>  inside this tag the attribute “trackback:ping” have a url where we can send trackback. 2. you need some information about your blog to post where you want to trackback like 1. URL where you want to send the trackback 2. your post title [may be page title] 3. your post URL [may be page url] 4.  Excerpt : information you want to send. 5. you blogname [may be sitename if you use site not blog] make the information like querystring just we use in asp.net ex: title=”pingpost&url=pingurl&excerpt=it’s me&blog=myblog” ; the information look like asp.net Querystring if you unsure that you can HTMLencode the information who you use in parameters. you need to be sure that your post have URL of post where you want to send trackback. make  a request to pingurl set the following property request.Method = “POST”; //because they support only POST request.ContentLength = param.length // choose the length of parameters we create for sending ping. request.ContentType = "application/x-www-form-urlencoded"; // required to set. now when you send the request then server respond you something about your request check that the request.statuscode is verify that’s work or not if (response.StatusCode < HttpStatusCode.OK && response.StatusCode >= HttpStatusCode.Ambiguous)                     throw new Exception(string.Format(response.StatusCode.ToString())); because you have the response in XML format you can parse the response that’s have Error tag inside them or not. i put here information not code the reason is that “i see some other blog from a week on the topic but i found that they[blogger] post code not the method and all their code are useless and not worked”. because i thing to be more declarative i post here the definition not code.

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• Bash Printing, how to

  - by Uncle Leo

  Wrote a script in bash. Now im need to bring information into a text file,for example in PostScript, but there is one problem. I need to have a certain length of string in characters, and stretch or shrink the string on the entire width of the page layout. I have tried a2ps and enscript, but there is no such option. Please tell me the solution to this problem, maybe in Ghostscript. Thanks in advance!

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• How to escape this in the bash script?

  - by allenskd

  I'm trying to complete a batch of 3 videos to leave it there till morning processing but it seems there are special characters in it... I try it "raw" in the terminal and it works but in bash script it stops working Example: args1="-r 29.97 -t 00:13:30 -vsync 0 -vpre libx264-medium -i" args12="-r 29.97 -ss 00:40:30 -vsync 0 -vpre libx264-medium -i" args2="[in] scale=580:380 [T1],[T1] pad=720:530:0:50 (other arguments with lots of [ and ]" In the output it says Unable to find a suitable output format for 'scale=580:380' not sure why... like I said, the command runs fine in the command-line, just not in the script /usr/local/bin/ffmpeg "$args1" "${file}" -vf "$args2" "$args3" "${args[0]}_${startingfrom}_0001_02.mp4"

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• Finding the XPath with the node name

  - by julien.schneider(at)oracle.com

  A function that i find missing is to get the Xpath expression of a node. For example, suppose i only know the node name <theNode>, i'd like to get its complete path /Where/is/theNode.   Using this rather simple Xquery you can easily get the path to your node. declare namespace orcl = "http://www.oracle.com/weblogic_soa_and_more"; declare function orcl:findXpath($path as element()*) as xs:string { if(local-name($path/..)='') then local-name($path) else concat(orcl:findXpath($path/..),'/',local-name($path)) }; declare function orcl:PathFinder($inputRecord as element(), $path as element()) as element(*) { { for $index in $inputRecord//*[local-name()=$path/text()] return orcl:findXpath($index) } }; declare variable $inputRecord as element() external; declare variable $path as element() external; orcl:PathFinder($inputRecord, $path)   With a path         <myNode>nodeName</myNode>  and a message         <node1><node2><nodeName>test</nodeName></node2></node1>  the result will be         node1/node2/nodeName   This is particularly useful when you use the Validate action of OSB because Validate only returns the xml node which is in error and not the full location itself. The following OSB project reuses this Xquery to reformat the result of the Validate Action. Just send an invalid xml like <myElem http://blogs.oracle.com/weblogic_soa_and_more"http://blogs.oracle.com/weblogic_soa_and_more">      <mySubElem>      </mySubElem></myElem>   you'll get as nice <MessageIsNotValid> <ErrorDetail  nbr="1"> <dataElementhPath>Body/myElem/mySubElem</dataElementhPath> <message> Expected element 'Subelem1@http://blogs.oracle.com/weblogic_soa_and_more' before the end of the content in element mySubElem@http://blogs.oracle.com/weblogic_soa_and_more </message> </ErrorDetail> </MessageIsNotValid>   Download the OSB project : sbconfig_xpath.jar   Enjoy.            

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• Rule of thumb for enemy art design in 2D platformer

  - by Terrance

  I'm at the early stages of developing a 2D side scrolling open ended platformer (think Metroidvania) and am having a bit of difficulty at enemy design inspiration for something of a scifi, nature, fantasy setting that isn't overly familar or obvious. I haven't seen too many articles, blogs or books that talk about the subject at great length. Is there a fair rule of thumb when coming up with enemy art with respect to keeping your player engaged?

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• XNA 2D line-of-sight check

  - by bionicOnion

  I'm working on a top-down shooter in XNA, and I need to implement line-of-sight checking. I've come up with a solution that seems to work, but I get the nagging feeling that it won't be efficient enough to do every frame for multiple calls (the game already hiccups slightly at about 10 calls per frame). The code is below, but my general plan was to create a series of rectangles with a width and height of zero to act as points along the sight line, and then check to see if any of these rectangles intersects a ClutterObject (an interface I defined for things like walls or other obstacles) after first screening for any that can't possibly be in the line of sight (i.e. behind the viewer) or are too far away (a concession I made for efficiency). public static bool LOSCheck(Vector2 pos1, Vector2 pos2) { Vector2 currentPos = pos1; Vector2 perMove = (pos2 - pos1); perMove.Normalize(); HashSet<ClutterObject> clutter = new HashSet<ClutterObject>(); foreach (Room r in map.GetRooms()) { if (r != null) { foreach (ClutterObject c in r.GetClutter()) { if (c != null &&!(c.GetRectangle().X * perMove.X < 0) && !(c.GetRectangle().Y * perMove.Y < 0)) { Vector2 cVector = new Vector2(c.GetRectangle().X, c.GetRectangle().Y); if ((cVector - pos1).Length() < 1500) clutter.Add(c); } } } } while (currentPos != pos2 && ((currentPos - pos1).Length() < 1500)) { Rectangle position = new Rectangle((int)currentPos.X, (int)currentPos.Y, 0, 0); foreach (ClutterObject c in clutter) { if (position.Intersects(c.GetRectangle())) return false; } currentPos += perMove; } return true; } I'm sure that there's a better way to do this (or at least a way to make this method more efficient), but I'm not too used to XNA yet, so I figured it couldn't hurt to bring it here. At the very least, is there an efficient to determine which objects may be in front of the viewer with greater precision than the rather broad 90 degree window I've given myself?

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• Critique of the IO monad being viewed as a state monad operating on the world

  - by Petr Pudlák

  The IO monad in Haskell is often explained as a state monad where the state is the world. So a value of type IO a monad is viewed as something like worldState -> (a, worldState). Some time ago I read an article (or a blog/mailing list post) that criticized this view and gave several reasons why it's not correct. But I cannot remember neither the article nor the reasons. Anybody knows? Edit: The article seems lost, so let's start gathering various arguments here. I'm starting a bounty to make things more interesting.

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• Collision detection - Smooth wall sliding, no bounce effect

  - by Joey

  I'm working on a basic collision detection system that provides point - OBB collision detection. I have around 200 cubes in my environment and I check (for now) each of them in turn and see if it collides. If it does I return the colliding face's normal, save the old player position and do some trigonometry to return a new player position for my wall sliding. edit I'll define my meaning of wall sliding: If a player walks in a vertical slope and has a slight horizontal rotation to the left or the right and keeps walking forward in the wall the player should slide a little to the right/left while continually walking towards the wall till he left the wall. Thus, sliding along the wall. Everything works fine and with multiple objects as well but I still have one problem I can't seem to figure out: smooth wall sliding. In my current implementation sliding along the walls make my player bounce like a mad man (especially noticable with gravity on and moving forward). I have a velocity/direction vector, a normal vector from the collided plane and an old and new player position. First I negate the normal vector and get my new velocity vector by substracting the inverted normal from my direction vector (which is the vector to slide along the wall) and I add this vector to my new Player position and recalculate the direction vector (in case I have multiple collisions). I know I am missing some step but I can't seem to figure it out. Here is my code for the collision detection (run every frame): Vector direction; Vector newPos(camera.GetOriginX(), camera.GetOriginY(), camera.GetOriginZ()); direction = newPos - oldPos; // Direction vector // Check for collision with new position for(int i = 0; i < NUM_OBJECTS; i++) { Vector normal = objects[i].CheckCollision(newPos.x, newPos.y, newPos.z, direction.x, direction.y, direction.z); if(normal != Vector::NullVector()) { // Get inverse normal (direction STRAIGHT INTO wall) Vector invNormal = normal.Negative(); Vector wallDir = direction - invNormal; // We know INTO wall, and DIRECTION to wall. Substract these and you got slide WALL direction newPos = oldPos + wallDir; direction = newPos - oldPos; } } Any help would be greatly appreciated! FIX I eventually got things up and running how they should thanks to Krazy, I'll post the updated code listing in case someone else comes upon this problem! for(int i = 0; i < NUM_OBJECTS; i++) { Vector normal = objects[i].CheckCollision(newPos.x, newPos.y, newPos.z, direction.x, direction.y, direction.z); if(normal != Vector::NullVector()) { Vector invNormal = normal.Negative(); invNormal = invNormal * (direction * normal).Length(); // Change normal to direction's length and normal's axis Vector wallDir = direction - invNormal; newPos = oldPos + wallDir; direction = newPos - oldPos; } }

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• Getting Dynamic in SSIS Queries

  - by ejohnson2010

  When you start working with SQL Server and SSIS, it isn’t long before you find yourself wishing you could change bits of SQL queries dynamically. Most commonly, I see people that want to change the date portion of a query so that you can limit your query to the last 30 days, for example. This can be done using a combination of expressions and variables. I will do this in two parts, first I will build a variable that will always contain the 1 st day of the previous month and then I will dynamically...(read more)

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• Are there examples of non CRUD approaches?

  - by Pieter B

  I'm a programmer but also have worked as an archivist. As archivist it's a lot about keeping data. I often get into arguments with colleagues when it comes to operations on data. I don't like the U and the D in CRUD too much. Rather then update a record I prefer to add a new one and have a reference to the old record. That way you build a history of changes. I also don't like deleting records but rather mark them as inactive. Is there a term for this? Basically only creating and reading data? Are there examples of this approach?

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• C# Performance Pitfall – Interop Scenarios Change the Rules

  - by Reed

  C# and .NET, overall, really do have fantastic performance in my opinion.  That being said, the performance characteristics dramatically differ from native programming, and take some relearning if you’re used to doing performance optimization in most other languages, especially C, C++, and similar.  However, there are times when revisiting tricks learned in native code play a critical role in performance optimization in C#. I recently ran across a nasty scenario that illustrated to me how dangerous following any fixed rules for optimization can be… The rules in C# when optimizing code are very different than C or C++.  Often, they’re exactly backwards.  For example, in C and C++, lifting a variable out of loops in order to avoid memory allocations often can have huge advantages.  If some function within a call graph is allocating memory dynamically, and that gets called in a loop, it can dramatically slow down a routine. This can be a tricky bottleneck to track down, even with a profiler.  Looking at the memory allocation graph is usually the key for spotting this routine, as it’s often “hidden” deep in call graph.  For example, while optimizing some of my scientific routines, I ran into a situation where I had a loop similar to: for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i]); } .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; } This loop was at a fairly high level in the call graph, and often could take many hours to complete, depending on the input data.  As such, any performance optimization we could achieve would be greatly appreciated by our users. After a fair bit of profiling, I noticed that a couple of function calls down the call graph (inside of ProcessElement), there was some code that effectively was doing: // Allocate some data required DataStructure* data = new DataStructure(num); // Call into a subroutine that passed around and manipulated this data highly CallSubroutine(data); // Read and use some values from here double values = data->Foo; // Cleanup delete data; // ... return bar; Normally, if “DataStructure” was a simple data type, I could just allocate it on the stack.  However, it’s constructor, internally, allocated it’s own memory using new, so this wouldn’t eliminate the problem.  In this case, however, I could change the call signatures to allow the pointer to the data structure to be passed into ProcessElement and through the call graph, allowing the inner routine to reuse the same “data” memory instead of allocating.  At the highest level, my code effectively changed to something like: DataStructure* data = new DataStructure(numberToProcess); for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i], data); } delete data; Granted, this dramatically reduced the maintainability of the code, so it wasn’t something I wanted to do unless there was a significant benefit.  In this case, after profiling the new version, I found that it increased the overall performance dramatically – my main test case went from 35 minutes runtime down to 21 minutes.  This was such a significant improvement, I felt it was worth the reduction in maintainability. In C and C++, it’s generally a good idea (for performance) to: Reduce the number of memory allocations as much as possible, Use fewer, larger memory allocations instead of many smaller ones, and Allocate as high up the call stack as possible, and reuse memory I’ve seen many people try to make similar optimizations in C# code.  For good or bad, this is typically not a good idea.  The garbage collector in .NET completely changes the rules here. In C#, reallocating memory in a loop is not always a bad idea.  In this scenario, for example, I may have been much better off leaving the original code alone.  The reason for this is the garbage collector.  The GC in .NET is incredibly effective, and leaving the allocation deep inside the call stack has some huge advantages.  First and foremost, it tends to make the code more maintainable – passing around object references tends to couple the methods together more than necessary, and overall increase the complexity of the code.  This is something that should be avoided unless there is a significant reason.  Second, (unlike C and C++) memory allocation of a single object in C# is normally cheap and fast.  Finally, and most critically, there is a large advantage to having short lived objects.  If you lift a variable out of the loop and reuse the memory, its much more likely that object will get promoted to Gen1 (or worse, Gen2).  This can cause expensive compaction operations to be required, and also lead to (at least temporary) memory fragmentation as well as more costly collections later. As such, I’ve found that it’s often (though not always) faster to leave memory allocations where you’d naturally place them – deep inside of the call graph, inside of the loops.  This causes the objects to stay very short lived, which in turn increases the efficiency of the garbage collector, and can dramatically improve the overall performance of the routine as a whole. In C#, I tend to: Keep variable declarations in the tightest scope possible Declare and allocate objects at usage While this tends to cause some of the same goals (reducing unnecessary allocations, etc), the goal here is a bit different – it’s about keeping the objects rooted for as little time as possible in order to (attempt) to keep them completely in Gen0, or worst case, Gen1.  It also has the huge advantage of keeping the code very maintainable – objects are used and “released” as soon as possible, which keeps the code very clean.  It does, however, often have the side effect of causing more allocations to occur, but keeping the objects rooted for a much shorter time. Now – nowhere here am I suggesting that these rules are hard, fast rules that are always true.  That being said, my time spent optimizing over the years encourages me to naturally write code that follows the above guidelines, then profile and adjust as necessary.  In my current project, however, I ran across one of those nasty little pitfalls that’s something to keep in mind – interop changes the rules. In this case, I was dealing with an API that, internally, used some COM objects.  In this case, these COM objects were leading to native allocations (most likely C++) occurring in a loop deep in my call graph.  Even though I was writing nice, clean managed code, the normal managed code rules for performance no longer apply.  After profiling to find the bottleneck in my code, I realized that my inner loop, a innocuous looking block of C# code, was effectively causing a set of native memory allocations in every iteration.  This required going back to a “native programming” mindset for optimization.  Lifting these variables and reusing them took a 1:10 routine down to 0:20 – again, a very worthwhile improvement. Overall, the lessons here are: Always profile if you suspect a performance problem – don’t assume any rule is correct, or any code is efficient just because it looks like it should be Remember to check memory allocations when profiling, not just CPU cycles Interop scenarios often cause managed code to act very differently than “normal” managed code. Native code can be hidden very cleverly inside of managed wrappers

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• Determining distribution of NULL values

  - by AaronBertrand

  Today on the twitter hash tag #sqlhelp, @leenux_tux asked: How can I figure out the percentage of fields that don't have data ? After further clarification, it turns out he is after what proportion of columns are NULL. Some folks suggested using a data profiling task in SSIS . There may be some validity to that, but I'm still a fan of sticking to T-SQL when I can, so here is how I would approach it: Create a #temp table or @table variable to store the results. Create a cursor that loops through all...(read more)

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