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  • Problems moving a rectangle in Pygame.

    - by Yann Core
    Hi guys! I'm making a game in Pygame and I want to be able to target enemy unit. I made it so when I click on them a variable "targeted" becomes true, and stays true until I click somewhere else on the screen. I also want targeted units to have a small green circle around them, so I made it in GEDIT. I have made a function that draws everything on the screen (the background, the player, objects, etc) and in the part where it draws the units it checks if the variable "targeted" is true and if it is it should move that little green circle over the enemy units. here is the code that does that: screen.blit(enemy_unit.pic, enemy_unit.rect) #draw the unit if enemy_unit.targeted == True: #if the unit has been targeted then draw a circle over it target_rect.move_ip(enemy_unit.pos) #move the circle to the unit target_rect.fit(enemy_unit.rect) #there are some bigger units and some smaller ones, so we have to "scale" the circle screen.blit(target_pic, target_rect) #actually draw the circle This doesn't work, when I target the unit the circle just appears for a 1/5 of second next (not on, but just next) to the unit and then disappears. I am sure that I am keeping a good track of "enemy_unit.pos" because I tested it (I added a piece of code that would print one units position and mouse's position every time i clicked the mouse and when i was near him the numbers were same). If you could give me a hint about what I'm doing wrong. I think its in move_ip function, but I tried just move and it didn't work either (the circle didn't even show at all)!

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  • batch: comparing filenames and renaming [migrated]

    - by user2978770
    i'm new to both this platform and batch programming and i'm slowly but steadily driving crazy :-( I'm studying in Germany and just started on a bigger project that mainly consists of analyzing data and finding algorithms in order to maintain a certain function of a system. In order to get started i got a bunch of recorded data that, unfortunately, is not consistent when i comes to naming. Normally all files (all in one folder) should start with SPY.SPYNODE.SIDE and then go on with the specific names for each values or variables. However, the data logger messed it up a couple of times and gives weird names like SP0E1A~1.csv (all files are .csv-files). An that's when i figured in stead of renaming a couple of thousand files manually i could "easily" use a simple batch file to do that job for name. And that's exactly when I started to go crazy :-) So far i came up with the following: FOR /R %%i in (%CD%) DO ( set file1=%%i if not %file1%=="SPY.SPYNODE.SIDE" DO ( set /p "filename" < %file1% rename %file1% %filename% ) ) So what i want it to do is this (in pseudo) look through the whole folder and every file save the filename in variable file1 if file1 partially equals SPY.SPYNODE.SIDE open the file and save the first line (which contains the correct name of the file) in variable filename rename the file with the correct filename But so far it doesn't really work and i don't know why. Could anybody give me a hint or some advice how i should proceed? I really appreciate any kind of help!

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  • XSL-FO: Force Wrap on Table Entries

    - by Ace
    I'm having an issue where when I publish my modspecs to pdf (XSL-FO). My tables are having issues, where the content of a cell will overflow its column into the next one. How do I force a break on the text so that a new line is created instead? I can't manually insert zero-space characters since the table entries are programmatically entered. I'm looking for a simple solution that I can just simply add to docbook_pdf.xsl (either as a xsl:param or xsl:attribute) EDIT: Here is where I'm at currently: <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0" xmlns:fo="http://www.w3.org/1999/XSL/Format"> <xsl:import href="urn:docbkx:stylesheet"/> ...(the beginning of my stylesheet for pdf generation, e.g. header and footer content stuff) <xsl:template match="text()"> <xsl:call-template name="intersperse-with-zero-spaces"> <xsl:with-param name="str" select="."/> </xsl:call-template> </xsl:template> <xsl:template name="intersperse-with-zero-spaces"> <xsl:param name="str"/> <xsl:variable name="spacechars"> &#x9;&#xA; &#x2000;&#x2001;&#x2002;&#x2003;&#x2004;&#x2005; &#x2006;&#x2007;&#x2008;&#x2009;&#x200A;&#x200B; </xsl:variable> <xsl:if test="string-length($str) &gt; 0"> <xsl:variable name="c1" select="substring($str, 1, 1)"/> <xsl:variable name="c2" select="substring($str, 2, 1)"/> <xsl:value-of select="$c1"/> <xsl:if test="$c2 != '' and not(contains($spacechars, $c1) or contains($spacechars, $c2))"> <xsl:text>&#x200B;</xsl:text> </xsl:if> <xsl:call-template name="intersperse-with-zero-spaces"> <xsl:with-param name="str" select="substring($str, 2)"/> </xsl:call-template> </xsl:if> </xsl:template> </xsl:stylesheet> With this, the long words are successfully broken up in the table cells! Unfortunately, the side effect is that normal text elsewhere (like in a under sextion X) now breaks up words so that they appear on seperate lines. Is there a way to isolate the above process to just tables? EDIT #2 here is what the fo spits out for a single table... <fo:table-row><fo:table-cell padding-start="2pt" padding-end="2pt" padding-top="2pt" ... </fo:block></fo:table-cell></fo:table-row>

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  • curl_init undefined?

    - by udaya
    Hi I am importing the contacts from gmail to my page ..... The process doesnot work due to this error 'curl_init' is not defined The suggestion i got is to 1.uncomment destination curl.dll 2.copy the following libraries to the windows/system32 dir. ssleay32.dll libeay32.dll 3.copy php_curl.dll to windows/system32 After trying all these i refreshed my xampp Even then error occurs This is my page where i am trying to import the gmail contacts ` // set URL and other appropriate options curl_setopt($ch, CURLOPT_URL, "http://www.example.com/"); curl_setopt($ch, CURLOPT_HEADER, 0); // grab URL and pass it to the browser curl_exec($ch); // close cURL resource, and free up system resources curl_close($ch); ? "HOSTED_OR_GOOGLE", "Email" = $_POST['Email'], echo "Passwd" = $_POST['Passwd'], "service" = "cp", "source" = "tutsmore/1.2" ); //Now we are going to post these datas to the clientLogin url. // Initialize the curl object with the $curl = curl_init($clientlogin_url); //Make the post true curl_setopt($curl, CURLOPT_POST, true); //Passing the above array of parameters. curl_setopt($curl, CURLOPT_POSTFIELDS, $clientlogin_post); //Set this for authentication and ssl communication. curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY); //provide false to not to check the server for the certificate. curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false); //Tell curl to just don't echo the data but return it to a variable. curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); //The variable containing response $response = curl_exec($curl); //Check whether the user is successfully login using the preg_match and save the auth key if the user //is successfully logged in preg_match("/Auth=([a-z0-9_-]+)/i", $response, $matches); $auth = $matches[1]; // Include the Auth string in the headers $headers = array("Authorization: GoogleLogin auth=" . $auth); // Make the request to the google contacts feed with the auth key $curl = curl_init('http://www.google.com/m8/feeds/contacts/default/full?max-results=10000'); //passing the headers of auth key. curl_setopt($curl, CURLOPT_HTTPHEADER, $headers); //Return the result in a variable curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); //the variable with the response. $feed = curl_exec($curl); //Create empty array of contacts echo "contacts".$contacts=array(); //Initialize the DOMDocument object $doc=new DOMDocument(); //Check whether the feed is empty //If not empty then load that feed. if (!empty($feed)) $doc-loadHTML($feed); //Initialize the domxpath object and provide the loaded feed $xpath=new DOMXPath($doc); //Get every entry tags from the feed. $query="//entry"; $data=$xpath-query($query); //Process each entry tag foreach ($data as $node) { //children of each entry tag. $entry_nodes=$node-childNodes; //Create a temproray array. $tempArray=array(); //Process the child node of the entry tag. foreach($entry_nodes as $child) { //get the tagname of the child node. $domNodesName=$child-nodeName; switch($domNodesName) { case 'title' : { $tempArray['fullName']=$child-nodeValue; } break; case 'email' : { if (strpos($child-getAttribute('rel'),'home')!==false) $tempArray['email_1']=$child-getAttribute('address'); elseif(strpos($child-getAttribute('rel'),'work')!=false) $tempArray['email_2']=$child-getAttribute('address'); elseif(strpos($child-getAttribute('rel'),'other')!==false) $tempArray['email_3']=$child-getAttribute('address'); } break; } } if (!empty($tempArray['email_1']))$contacts[$tempArray['email_1']]=$tempArray; if(!empty($tempArray['email_2'])) $contacts[$tempArray['email_2']]=$tempArray; if(!empty($tempArray['email_3'])) $contacts[$tempArray['email_3']]=$tempArray; } foreach($contacts as $key=$val) { //Echo the email echo $key.""; } } else { //The form ? " method="POST" Email: Password: tutsmore don't save your email and password trust us. ` code is completely provided for debugging if any optimization is needed i will try to optimize the code

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  • Getting a Temporary Table Returned from from Dynamic SQL in SQL Server 05, and parsing

    - by gloomy.penguin
    So I was requested to make a few things.... (it is Monday morning and for some reason this whole thing is turning out to be really hard for me to explain so I am just going to try and post a lot of my code; sorry) First, I needed a table: CREATE TABLE TICKET_INFORMATION ( TICKET_INFO_ID INT IDENTITY(1,1) NOT NULL, TICKET_TYPE INT, TARGET_ID INT, TARGET_NAME VARCHAR(100), INFORMATION VARCHAR(MAX), TIME_STAMP DATETIME DEFAULT GETUTCDATE() ) -- insert this row for testing... INSERT INTO TICKET_INFORMATION (TICKET_TYPE, TARGET_ID, TARGET_NAME, INFORMATION) VALUES (1,1,'RT_ID','IF_ID,int=1&IF_ID,int=2&OTHER,varchar(10)=val,ue3&OTHER,varchar(10)=val,ue4') The Information column holds data that needs to be parsed into a table. This is where I am having problems. In the resulting table, Target_Name needs to become a column that holds Target_ID as a value for each row in the resulting table. The string that needs to be parsed is in this format: @var_name1,@var_datatype1=@var_value1&@var_name2,@var_datatype2=@var_value2&@var_name3,@var_datatype3=@var_value3 And what I ultimately need as a result (in a table or table variable): RT_ID IF_ID OTHER 1 1 val,ue3 1 2 val,ue3 1 1 val,ue4 1 2 val,ue4 And I need to be able to join on the result. Initially, I was just going to make this a function that returns a table variable but for some reason I can't figure out how to get it into an actual table variable. Whatever parses the string needs to be able to be used directly in queries so I don't think a stored procedure is really the right thing to be using. This is the code that parses the Information string... it returns in a temporary table. -- create/empty temp table for var_name, var_type and var_value fields if OBJECT_ID('tempdb..#temp') is not null drop table #temp create table #temp (row int identity(1,1), var_name varchar(max), var_type varchar(30), var_value varchar(max)) -- just setting stuff up declare @target_name varchar(max), @target_id varchar(max), @info varchar(max) set @target_name = (select target_name from ticket_information where ticket_info_id = 1) set @target_id = (select target_id from ticket_information where ticket_info_id = 1) set @info = (select information from ticket_information where ticket_info_id = 1) --print @info -- some of these variables are re-used later declare @col_type varchar(20), @query varchar(max), @select as varchar(max) set @query = 'select ' + @target_id + ' as ' + @target_name + ' into #target; ' set @select = 'select * into ##global_temp from #target' declare @var_name varchar(100), @var_type varchar(100), @var_value varchar(100) declare @comma_pos int, @equal_pos int, @amp_pos int set @comma_pos = 1 set @equal_pos = 1 set @amp_pos = 0 -- while loop to parse the string into a table while @amp_pos < len(@info) begin -- get new comma position set @comma_pos = charindex(',',@info,@amp_pos+1) -- get new equal position set @equal_pos = charindex('=',@info,@amp_pos+1) -- set stuff that is going into the table set @var_name = substring(@info,@amp_pos+1,@comma_pos-@amp_pos-1) set @var_type = substring(@info,@comma_pos+1,@equal_pos-@comma_pos-1) -- get new ampersand position set @amp_pos = charindex('&',@info,@amp_pos+1) if @amp_pos=0 or @amp_pos<@equal_pos set @amp_pos = len(@info)+1 -- set last variable for insert into table set @var_value = substring(@info,@equal_pos+1,@amp_pos-@equal_pos-1) -- put stuff into the temp table insert into #temp (var_name, var_type, var_value) values (@var_name, @var_type, @var_value) -- is this a new field? if ((select count(*) from #temp where var_name = (@var_name)) = 1) begin set @query = @query + ' create table #' + @var_name + '_temp (' + @var_name + ' ' + @var_type + '); ' set @select = @select + ', #' + @var_name + '_temp ' end set @query = @query + ' insert into #' + @var_name + '_temp values (''' + @var_value + '''); ' end if OBJECT_ID('tempdb..##global_temp') is not null drop table ##global_temp exec (@query + @select) --select @query --select @select select * from ##global_temp Okay. So, the result I want and need is now in ##global_temp. How do I put all of that into something that can be returned from a function (or something)? Or can I get something more useful returned from the exec statement? In the end, the results of the parsed string need to be in a table that can be joined on and used... Ideally this would have been a view but I guess it can't with all the processing that needs to be done on that information string. Ideas? Thanks!

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  • My IDE is showing "undeclared FileNotFoundException must be caught or thrown"

    - by Dan Czarnecki
    I am having the following issue above. I have tried actually putting a try-catch statement into the code as you will see below, but I can't get the compiler to get past that. import java.io.*; public class DirectoryStatistics extends DirectorySize { /* Dan Czarnecki October 24, 2013 Class variables: private File directory A File object that holds the pathname of the directory to look in private long sizeInBytes A variable of type long that holds the size of a file/directory (in bytes) private long fileCount A variable of type long that holds the number of files in a directory Constructors: public DirectoryStatistics(File startingDirectory) throws FileNotFoundException Creates a DirectoryStatistics object, given a pathname (inherited from DirectorySize class), and has 3 instance variables that hold the directory to search in, the size of each file (in bytes), and the number of files within the directory Modification history: October 24, 2013 Original version of class */ private File directory; private long sizeInBytes; private long fileCount; public DirectoryStatistics(File startingDirectory) throws FileNotFoundException { super(startingDirectory); try { if(directory == null) { throw new IllegalArgumentException("null input"); } if(directory.isDirectory() == false) { throw new FileNotFoundException("the following input is not a directory!"); } } catch(IOException ioe) { System.out.println("You have not entered a directory. Please try again."); } } public File getDirectory() { return this.directory; } public long getSizeInBytes() { return this.sizeInBytes; } public long getFileCount() { return this.fileCount; } public long setFileCount(long size) { fileCount = size; return size; } public long setSizeInBytes(long size) { sizeInBytes = size; return size; } public void incrementFileCount() { fileCount = fileCount + 1; } public void addToSizeInBytes(long addend) { sizeInBytes = sizeInBytes + addend; } public String toString() { return "Directory" + this.directory + "Size (in bytes) " + this.sizeInBytes + "Number of files: " + this.fileCount; } public int hashCode() { return this.directory.hashCode(); } public boolean equals(DirectoryStatistics other) { return this.equals(other); } } import java.io.*; import java.util.*; public class DirectorySize extends DirectoryProcessor { /* Dan Czarnecki October 17, 2013 Class variables: private Vector<Long> directorySizeList Variable of type Vector<Long> that holds the total file size of files in that directory as well as files within folders of that directory private Vector<File> currentFile Variable of type Vector<File> that holds the parent directory Constructors: public DirectorySize(File startingDirectory) throws FileNotFoundException Creates a DirectorySize object, takes in a pathname (inherited from DirectoryProcessor class, and has a single vector of a DirectoryStatistics object to hold the files and folders within a directory Modification History October 17, 2013 Original version of class Implemented run() and processFile() methods */ private Vector<DirectoryStatistics> directory; /* private Vector<Long> directorySizeList; private Vector<File> currentFile; */ public DirectorySize(File startingDirectory) throws FileNotFoundException { super(startingDirectory); directory = new Vector<DirectoryStatistics>(); } public void processFile(File file) { DirectoryStatistics parent; int index; File parentFile; System.out.println(file.getName()); System.out.println(file.getParent()); parentFile = file.getParentFile(); parent = new DirectoryStatistics(parentFile); System.out.println(parent); parent.equals(parent); index = directory.indexOf(parent); if(index == 0) { directory.elementAt(index).addToSizeInBytes(file.length()); directory.elementAt(index).incrementFileCount(); } if(index < 0) { directory.addElement(parent); directory.lastElement().setSizeInBytes(file.length()); directory.lastElement().incrementFileCount(); } Could someone tell me why I'm getting this issue?

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  • Public class DiscoLight help

    - by luvthug
    Hi All, If some one can point me in the right direction for this code for my assigment I would really appreciate it. I have pasted the whole code that I need to complete but I need help with the following method public void changeColour(Circle aCircle) which is meant to allow to change the colour of the circle randomly, if 0 comes the light of the circle sgould change to red, 1 for green and 2 for purple. public class DiscoLight { /* instance variables */ private Circle light; // simulates a circular disco light in the Shapes window private Random randomNumberGenerator; /** * Default constructor for objects of class DiscoLight */ public DiscoLight() { super(); this.randomNumberGenerator = new Random(); } /** * Returns a randomly generated int between 0 (inclusive) * and number (exclusive). For example if number is 6, * the method will return one of 0, 1, 2, 3, 4, or 5. */ public int getRandomInt(int number) { return this.randomNumberGenerator.nextInt(number); } /** * student to write code and comment here for setLight(Circle) for Q4(i) */ public void setLight(Circle aCircle) { this.light = aCircle; } /** * student to write code and comment here for getLight() for Q4(i) */ public Circle getLight() { return this.light; } /** * Sets the argument to have a diameter of 50, an xPos * of 122, a yPos of 162 and the colour GREEN. * The method then sets the receiver's instance variable * light, to the argument aCircle. */ public void addLight(Circle aCircle) { //Student to write code here, Q4(ii) this.light = aCircle; this.light.setDiameter(50); this.light.setXPos(122); this.light.setYPos(162); this.light.setColour(OUColour.GREEN); } /** * Randomly sets the colour of the instance variable * light to red, green, or purple. */ public void changeColour(Circle aCircle) { //student to write code here, Q4(iii) if (getRandomInt() == 0) { this.light.setColour(OUColour.RED); } if (this.getRandomInt().equals(1)) { this.light.setColour(OUColour.GREEN); } else if (this.getRandomInt().equals(2)) { this.light.setColour(OUColour.PURPLE); } } /** * Grows the diameter of the circle referenced by the * receiver's instance variable light, to the argument size. * The diameter is incremented in steps of 2, * the xPos and yPos are decremented in steps of 1 until the * diameter reaches the value given by size. * Between each step there is a random colour change. The message * delay(anInt) is used to slow down the graphical interface, as required. */ public void grow(int size) { //student to write code here, Q4(iv) } /** * Shrinks the diameter of the circle referenced by the * receiver's instance variable light, to the argument size. * The diameter is decremented in steps of 2, * the xPos and yPos are incremented in steps of 1 until the * diameter reaches the value given by size. * Between each step there is a random colour change. The message * delay(anInt) is used to slow down the graphical interface, as required. */ public void shrink(int size) { //student to write code here, Q4(v) } /** * Expands the diameter of the light by the amount given by * sizeIncrease (changing colour as it grows). * * The method then contracts the light until it reaches its * original size (changing colour as it shrinks). */ public void lightCycle(int sizeIncrease) { //student to write code here, Q4(vi) } /** * Prompts the user for number of growing and shrinking * cycles. Then prompts the user for the number of units * by which to increase the diameter of light. * Method then performs the requested growing and * shrinking cycles. */ public void runLight() { //student to write code here, Q4(vii) } /** * Causes execution to pause by time number of milliseconds */ private void delay(int time) { try { Thread.sleep(time); } catch (Exception e) { System.out.println(e); } } }

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  • Why does Saxon evaluate the result-document URI to be the same?

    - by Jan
    My XSL source document looks like this <Topology> <Environment> <Id>test</Id> <Machines> <Machine> <Id>machine1</Id> <modules> <module>m1</module> <module>m2</module> </modules> </Machine> </Machines> </Environment> <Environment> <Id>production</Id> <Machines> <Machine> <Id>machine1</Id> <modules> <module>m1</module> <module>m2</module> </modules> </Machine> <Machine> <Id>machine2</Id> <modules> <module>m3</module> <module>m4</module> </modules> </Machine> </Machines> </Environment> </Topology> I want to create one result-document per machine, so I use the following stylesheet giving modelDir as path for the result-documents as parameter. <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" name="myXML" doctype-system="http://java.sun.com/dtd/properties.dtd"/> <xsl:template match="/"> <xsl:for-each-group select="/Topology/Environment/Machines/Machine" group-by="Id"> <xsl:variable name="machine" select="Id"/> <xsl:variable name="filename" select="concat($modelDir,$machine,'.xml')" /> <xsl:message terminate="no">Writing machine description to <xsl:value-of select="$filename"/></xsl:message> <xsl:result-document href="$filename" format="myXML"> <xsl:variable name="currentMachine" select="Id"/> <xsl:for-each select="current-group()/LogicalHosts/LogicalHost"> <xsl:variable name="environment" select="normalize-space(../../../../Id)"/> <xsl:message terminate="no">Module <xsl:value-of select="."/> for <xsl:value-of select="$environment"/></xsl:message> </xsl:for-each> </xsl:result-document> </xsl:for-each-group> </xsl:template> As my messages show me this seems to work fine - if saxon would not evaluate the URI of the result-document to be the same and thus give the following output. Writing machine description to target/build/model/m1.xml Module m1 for test Module m2 for test Module m1 for production Module m2 for production Writing machine description to target/build/model/m2.xml Error at xsl:result-document on line 29 of file:/C:/Projekte/.../machine.xsl: XTDE1490: Cannot write more than one result document to the same URI, or write to a URI that has been read: file:/C:/Projekte/.../$filename file:/C:/Projekte/.../machine.xsl(29,-1) : here Cannot write more than one result document to the same URI, or write to a URI that has been read: file:/C:/Projekte/.../$filename ; SystemID: file:/C:/Projekte/.../machine.xsl; Line#: 29; Column#: -1 net.sf.saxon.trans.DynamicError: Cannot write more than one result document to the same URI, or write to a URI that has been read: file:/C:/Projekte/.../$filename at net.sf.saxon.instruct.ResultDocument.processLeavingTail(ResultDocument.java:300) at net.sf.saxon.instruct.Block.processLeavingTail(Block.java:365) at net.sf.saxon.instruct.Instruction.process(Instruction.java:91) Any ideas on how to solve this?

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  • Future of VB.NET? [closed]

    - by Alex Yeung
    Hi all, I worked with C# for years. Last year, I changed my job and the company use VB.NET. Of course, theoretically C# and VB.NET are very similar and I easily adapted. However, I have worked for VB.NET for 1 year. I cannot see any future of VB.NET. As a programming language, it is so foo. Here is a list of what C# can do but VB.NET cannot Case insensitive variables how to think a new variable name? If I have a property called FolderPath, i need to establish another private variable called _folderPath or m_folderPath. In C#, FolderPath and folderPath are two variables. Moreover, it gets compile error if variable name is same as a class name. For example Dim guid = Guid.NewGuid(). (What the...) Again, I need to think a new variable name. Adhoc scope In C#, we could use {...} to create a adhoc scope and all resource in {...} will not affect the code outside. However there is not such syntax in VB.NET. I could only use If True Then and End If to make a local scope which is so unclear. In-Method Region Sometime, it is unavoidable to have a long long method. VB.NET does not support in-method region. I always need to scroll down for 1000 lines. It wastes my time. No multi-line string definition In C#, we could var s = @"..." to define a multi-line string. In VB.NET there is no direct method to do that. The indirect way is use XML-literal string. Dim s = <![CDATA[...]]>.Value. However it is unclear. No block comment In C#, we have line comment // and block comment /* ... */. However in VB.NET we only have line comment which is a very big trouble for me. No statement end symbol Statements are separated by line break in VB.NET; while statements are separated by ; in C#. Underscore I think many people know underscore _ is continue statement symbol. I really disagree with that. I know MS VB.NET language team is going to remove the underscore syntax from VB.NET. However what can we do now? Although underscore is removed in the future, what's the advantage of that? I cannot see any advantage! With scope With scope is an evil scope. Although it allows shorter statement, it is hard to trace. Default Namesapce in project level It is a nightmare for me. The only advantage of VB.NET is property initialization. I think C# cannot do that (correct me if I am wrong.) Public Property ThisIsMyProperty As String = "MyValue" Remarks: I don't think optional method parameters is an advantage of OOP. By those disadvantages, I cannot see the future of VB.NET. Anyone sees the future of VB.NET?

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  • Looking for best practise for writing a serial device communication app in C#

    - by cdotlister
    I am pretty new to serial comms, but would like advise on how to best achieve a robust application which speak to and listens to a serial device. I have managed to make use of System.IO.serialport, and successfully connected to, sent data to and recieved from my device. The way things work is this. My application connects to the Com Port and opens the port.... I then connect my device to the com port, and it detects a connectio to the PC, so sends a bit of text. it's really just copyright info, as well as the version of the firmware. I don't do anything with that, except display it in my 'activity' window. The device then waits. I can then query information, but sending a command such as 'QUERY PARAMETER1'. It then replies with something like: 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n' I then process that. I can then update it by sending 'SET PARAMETER1 12345', and it will reply with 'QUERY PARAMETER1\r\n\r\n12345\r\n\r\n'. All pretty basic. So, what I have done is created a Communication Class. this call is called in it's own thread, and sends data back to the main form... and also allows me to send messages to it. Sending data is easy. Recieving is a bit more tricky. I have employed the use of the datarecieved event, and when ever data comes in, I echo that to my screen. My problem is this: When I send a command, I feel I am being very dodgy in my handling. What I am doing is, lets say I am sending 'QUERY PARAMETER1'. I send the command to the device, I then put 'PARAMETER1' into a global variable, and I do a Thread.Sleep(100). On the data recieved, I then have a bit of logic that checks the incoming data, and sees if the string CONTAINS the value in the gloabl variable. As the reply may be 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n', it sees that it contains my parameter, parses the string, and returns the value I am looking for, but placing it into another global variable. My sending method was sleeping for 100ms. It then wakes, and checks the returned global variable. If it has data... then I'm happy, and I process the data. Problem is... if the sleep is too short.. it will fail. And I feel it's flakey.. putting stuff into variables.. then waiting... The other option is to use ReadLine instead, but that's very blocking. So I remove the datarecieved method, and instead... just send the data... then call ReadLine(). That may give me better results. There's no time, except when we connect initially, that data comes from the device, without me requesting it. So, maybe readline will be simpler and safer? Is this known as 'Blocking' reads? Also, can I set a timeout? Hopefully someone can guide me.

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  • get user selection and convert it to a String [Android]

    - by Kira
    Hello, I just got a Droid, and after having used it for a while, I felt like I wanted to make a program for it. The program that I am trying to make calculates the actual storage capacity of secondary storage mediums. The user select from a list of units that ranges from KB to YB and the size the entered gets put into a formula depending on the chosen unit. However, there is a bit of a problem with the program. From my testing, I have narrowed it down to the fact that the user's selection is not really being obtained from the spinner. Everything I look up seems to point me to a method quite similar to how it works in J2SE, but it does nothing. How am I actually supposed to get that data? Here is the Java source code for the app: package com.Actual.android; import android.app.Activity; import android.os.Bundle; import android.widget.*; import android.view.*; public class ActualStorageActivity extends Activity { Spinner selection; /* declare variable, in order to control spinner (ComboBox) */ ArrayAdapter adapter; /* declare an array adapter object, in order for spinner to work */ EditText size; /* declare variable to control textfield */ EditText result; /* declare variable to control textfield */ Button calculate; /* declare variable to control button */ Storage capacity = new Storage(); /* import custom class for formulas */ /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // load content from XML selection = (Spinner)findViewById(R.id.spinner); adapter = ArrayAdapter.createFromResource(this, R.array.choices_array, android.R.layout.simple_spinner_dropdown_item); size = (EditText)findViewById(R.id.size); result = (EditText)findViewById(R.id.result); calculate = (Button)findViewById(R.id.submit); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); /* set resource for dropdown */ selection.setAdapter(adapter); // attach adapter to spinner result.setEnabled(false); // make read-only result.setText("usable storage"); } public void calcAction(View view) { String initial = size.getText().toString(); String unit = selection.getSelectedItem().toString(); String end = "Nothing"; double convert = Double.parseDouble(initial); capacity.setStorage(convert); if (unit == "KB") { end = Double.toString(capacity.getKB()); } else if (unit == "MB") { end = Double.toString(capacity.getMB()); } else if (unit == "GB") { end = Double.toString(capacity.getGB()); } else if (unit == "TB") { end = Double.toString(capacity.getTB()); } else if (unit == "PB") { end = Double.toString(capacity.getPB()); } else if (unit == "EB") { end = Double.toString(capacity.getEB()); } else if (unit == "ZB") { end = Double.toString(capacity.getZB()); } else if (unit == "YB") { end = Double.toString(capacity.getYB()); } else; result.setText(end); } }

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  • Looking for best practise for writing a serial device communication app

    - by cdotlister
    I am pretty new to serial comms, but would like advise on how to best achieve a robust application which speak to and listens to a serial device. I have managed to make use of System.IO.SerialPort, and successfully connected to, sent data to and recieved from my device. The way things work is this. My application connects to the Com Port and opens the port.... I then connect my device to the com port, and it detects a connection to the PC, so sends a bit of text. it's really just copyright info, as well as the version of the firmware. I don't do anything with that, except display it in my 'activity' window. The device then waits. I can then query information, but sending a command such as 'QUERY PARAMETER1'. It then replies with something like: 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n' I then process that. I can then update it by sending 'SET PARAMETER1 12345', and it will reply with 'QUERY PARAMETER1\r\n\r\n12345\r\n\r\n'. All pretty basic. So, what I have done is created a Communication Class. this call is called in it's own thread, and sends data back to the main form... and also allows me to send messages to it. Sending data is easy. Recieving is a bit more tricky. I have employed the use of the datarecieved event, and when ever data comes in, I echo that to my screen. My problem is this: When I send a command, I feel I am being very dodgy in my handling. What I am doing is, lets say I am sending 'QUERY PARAMETER1'. I send the command to the device, I then put 'PARAMETER1' into a global variable, and I do a Thread.Sleep(100). On the data received, I then have a bit of logic that checks the incoming data, and sees if the string CONTAINS the value in the global variable. As the reply may be 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n', it sees that it contains my parameter, parses the string, and returns the value I am looking for, but placing it into another global variable. My sending method was sleeping for 100ms. It then wakes, and checks the returned global variable. If it has data... then I'm happy, and I process the data. Problem is... if the sleep is too short.. it will fail. And I feel it's flaky.. putting stuff into variables.. then waiting... The other option is to use ReadLine instead, but that's very blocking. So I remove the data received method, and instead... just send the data... then call ReadLine(). That may give me better results. There's no time, except when we connect initially, that data comes from the device, without me requesting it. So, maybe ReadLine will be simpler and safer? Is this known as 'Blocking' reads? Also, can I set a timeout? Hopefully someone can guide me.

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  • A view interface for large object/array dumps

    - by user685107
    I want to embed in a page a detailed structure report of my model objects, like print_r() or var_export() produce (now I’m doing this with running var_export() on get_object_vars()). But what I actually want to see is only some properties (in most cases), but at this moment I have to use Ctrl+F and seek the variable I want, instead of just staring at it right after the page completes loading. So I’m embedding buttons to show/hide large arrays etc. but thought: ‘What if there already is the thing I do right now?’ So is there? Update: What would your ideal interface look like? First of all, dumped models fit in the first screen. All the properties can be seen at the first look at the screen (there are not many of them, around 10 per each, three models total, so it is possible). Small arrays can be shown unrolled too. Let the size of the array to count it as ‘small’ be definable. Ideally, the user can see values of the properties without doing any click, scrolling the screen or typing something. There must be some improvements to representing the values, say, if an array is empty, show array ‘My_big_array’ is empty and if a boolean variable starting with is_, has_, had_ has a false as the value, make the variable (let us take is_available for example) shown as is_NOT_available in red, and if it has true as the value, show is_available in green. Without any value shown. The same goes for defined constants. That would be ideal. I want to make focus on this kind of switches. Krumo seems useful, but since it always closes up the variable without making difference of how large it is, I cannot use it as is, but there might appear something similar on github soon :) Second update starts here: Any programmer who sees is_available = false will know what it means, no need to do more Bringing in color indication I forgot about one thing: the ‘switches’ let’s call them so, may me important or not. So I have right now some of them that will show in green or red, this is for something global, like caching, which is shown as Caching is… ON with ‘ON’ written in green, (and ‘OFF’ in red when disabled) while the words about what it is, i.e. ‘Caching is… ’ are written in black. And some which are not so important, for example I haven’t defined REVEAL_TIES is… not set with ‘not set’ written in gray, while the words describing what it is stay in black. And if it would be set the whole phrase would be in black since there is nothing important: if this small utility for showing some undercover things is working, I will see some messages after it, if it isn’t — site will be working independently of its state. Dividing switches into important ones and not with corresponding color match should improve readability, especially for those users who are not programmers and just enabled debug mode because some guy from bugzilla said do that — for them it would help to understand what is important and what is not.

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  • Connection drop problem with Hibernate-mysql-c3p0

    - by user344788
    hi all, This is an issue which I have seen all across the web. I will bring it up again as till now I don't have a fix for the same. I am using hibernate 3. mysql 5 and latest c3p0 jar. I am getting a broken pipe exception. Following is my hibernate.cfg file. com.mysql.jdbc.Driver org.hibernate.dialect.MySQLDialect <property name="hibernate.show_sql">true</property> <property name="hibernate.use_sql_comments">true</property> <property name="hibernate.current_session_context_class">thread</property> <property name="connection.autoReconnect">true</property> <property name="connection.autoReconnectForPools">true</property> <property name="connection.is-connection-validation-required">true</property> <!--<property name="c3p0.min_size">5</property> <property name="c3p0.max_size">20</property> <property name="c3p0.timeout">1800</property> <property name="c3p0.max_statements">50</property> --><property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider </property> <property name="hibernate.c3p0.acquireRetryAttempts">30</property> <property name="hibernate.c3p0.acquireIncrement">5</property> <property name="hibernate.c3p0.automaticTestTable">C3P0TestTable</property> <property name="hibernate.c3p0.idleConnectionTestPeriod">36000</property> <property name="hibernate.c3p0.initialPoolSize">20</property> <property name="hibernate.c3p0.maxPoolSize">100</property> <property name="hibernate.c3p0.maxIdleTime">1200</property> <property name="hibernate.c3p0.maxStatements">50</property> <property name="hibernate.c3p0.minPoolSize">10</property>--> My connection pooling is occurring fine. During the day it is fine , but once i keep it idle over the night ,next day I find it giving me broken connection error. public class HibernateUtil { private static Logger log = Logger.getLogger(HibernateUtil.class); //private static Log log = LogFactory.getLog(HibernateUtil.class); private static Configuration configuration; private static SessionFactory sessionFactory; static { // Create the initial SessionFactory from the default configuration files try { log.debug("Initializing Hibernate"); // Read hibernate.properties, if present configuration = new Configuration(); // Use annotations: configuration = new AnnotationConfiguration(); // Read hibernate.cfg.xml (has to be present) configuration.configure(); // Build and store (either in JNDI or static variable) rebuildSessionFactory(configuration); log.debug("Hibernate initialized, call HibernateUtil.getSessionFactory()"); } catch (Throwable ex) { // We have to catch Throwable, otherwise we will miss // NoClassDefFoundError and other subclasses of Error log.error("Building SessionFactory failed.", ex); throw new ExceptionInInitializerError(ex); } } /** * Returns the Hibernate configuration that was used to build the SessionFactory. * * @return Configuration */ public static Configuration getConfiguration() { return configuration; } /** * Returns the global SessionFactory either from a static variable or a JNDI lookup. * * @return SessionFactory */ public static SessionFactory getSessionFactory() { String sfName = configuration.getProperty(Environment.SESSION_FACTORY_NAME); System.out.println("Current s name is "+sfName); if ( sfName != null) { System.out.println("Looking up SessionFactory in JNDI"); log.debug("Looking up SessionFactory in JNDI"); try { System.out.println("Returning new sssion factory"); return (SessionFactory) new InitialContext().lookup(sfName); } catch (NamingException ex) { throw new RuntimeException(ex); } } else if (sessionFactory == null) { System.out.println("calling rebuild session factory now"); rebuildSessionFactory(); } return sessionFactory; } /** * Closes the current SessionFactory and releases all resources. * <p> * The only other method that can be called on HibernateUtil * after this one is rebuildSessionFactory(Configuration). */ public static void shutdown() { log.debug("Shutting down Hibernate"); // Close caches and connection pools getSessionFactory().close(); // Clear static variables sessionFactory = null; } /** * Rebuild the SessionFactory with the static Configuration. * <p> * Note that this method should only be used with static SessionFactory * management, not with JNDI or any other external registry. This method also closes * the old static variable SessionFactory before, if it is still open. */ public static void rebuildSessionFactory() { log.debug("Using current Configuration to rebuild SessionFactory"); rebuildSessionFactory(configuration); } /** * Rebuild the SessionFactory with the given Hibernate Configuration. * <p> * HibernateUtil does not configure() the given Configuration object, * it directly calls buildSessionFactory(). This method also closes * the old static variable SessionFactory before, if it is still open. * * @param cfg */ public static void rebuildSessionFactory(Configuration cfg) { log.debug("Rebuilding the SessionFactory from given Configuration"); if (sessionFactory != null && !sessionFactory.isClosed()) sessionFactory.close(); if (cfg.getProperty(Environment.SESSION_FACTORY_NAME) != null) { log.debug("Managing SessionFactory in JNDI"); cfg.buildSessionFactory(); } else { log.debug("Holding SessionFactory in static variable"); sessionFactory = cfg.buildSessionFactory(); } configuration = cfg; } } Above is my code for the session factory. And I have only select operations . And below is the method which is used most often to execute my select queries. One tricky thing which I am not understanding is in my findById method i am using this line of code getSession().beginTransaction(); without which it gives me an error saying that this cannot happpen without a transaction. But nowhere I am closing this transaction. And thers no method to close a transaction apart from commit or rollback (as far as i know) which are not applicable for select statements. public T findById(ID id, boolean lock) throws HibernateException, DAOException { log.debug("findNyId invoked with ID ="+id+"and lock ="+lock); T entity; getSession().beginTransaction(); if (lock) entity = (T) getSession().load(getPersistentClass(), id, LockMode.UPGRADE); else entity = (T) getSession().load(getPersistentClass(), id); return entity; } Can anyone please suggest what can I do ? I have tried out almost every solution available via googling, on stackoverlow or on hibernate forums with no avail. (And increasing wait_timeout on mysql is not a valid option in my case).

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  • Im getting fatal errors... can anyone help me edit my program!

    - by user350217
    The errors i am getting are: Error 1 error LNK2019: unresolved external symbol "double __cdecl getDollarAmt(void)" (? getDollarAmt@@YANXZ) referenced in function _main hid.obj Error 2 fatal error LNK1120: 1 unresolved externals this is my program: #include<iostream> #include<cmath> #include<string> using namespace std; double getDollarAmt(); void displayCurrencies(); char getCurrencySelection (float amtExchanged); bool isSelectionValid(char selection); double calcExchangeAmt (float amtExchanged, char selection); void displayResults(double newAmount, float amtExchanged, char selection, char yesNo); const double russianRubles = 31.168; const double northKoreanWon = .385; const double chineseYuan = 6.832; const double canadianDollar = 1.1137; const double cubanPeso = 1.0; const double ethiopianBirr = 9.09; const double egyptianPound = 5.6275; const double tunisianDinar = 1.3585; const double thaiBaht = 34.4; /****** I changed the variables to global variables so you don't have to worry about accidentally setting them to 0 or assigning over a value that you need ********/ float amtEchanged = 0.0; char selection; char yesNo; double newAmount; int main() { float amtExchanged = 0.0; selection = 'a'; yesNo = 'y'; newAmount = 0.0; getDollarAmt (); displayCurrencies(); getCurrencySelection (amtExchanged); isSelectionValid(selection);/**** you only need to use the selection variable ****/ calcExchangeAmt (amtExchanged, selection); displayResults(newAmount, amtExchanged, selection, yesNo); return 0; } double getDollarAmt (float amtExchanged) // promt user for eachange amount and return it to main { float amtExchanged0;//created temporary variable to set amtExchanged to cout<< "Please enter the total dollar amount to exchange: "; cin>> amtExchanged0; amtExchanged = amtExchanged0;//setting amtExchanged to the right value return amtExchanged; } void displayCurrencies() // display list of currencies { cout<<"A Russian Ruble"<<endl <<"B North Korean Won"<<endl <<"C Chinese Yuan"<<endl <<"D Cuban Peso"<<endl <<"E Ethiopian Birr"<<endl <<"F Thai Baht"<<endl <<"G Canadian Dollars"<<endl <<"H Tunisian Dinar"<<endl <<"I Egyptian Pound"<<endl; } char getCurrencySelection (float amtExchanged) // make a selection and return to main { char selection0;//again, created a temporary variable for selection cout<<"Please enter your selection: "; cin>>selection0; selection = selection0;//setting the temporary variable to the actual variable you use /***** we are now going to see if isSelectionValid returns false. if it returns false, that means that their selection was not character A-H. if it is false we keep calling getCurrencySelection *****/ if(isSelectionValid(selection)==false) { cout<<"Sorry, the selection you chose is invalid."<<endl; getCurrencySelection(amtExchanged); } return selection; } bool isSelectionValid(char selection) // this fuction is supposed to be called from getCurrencySelection, the selction // must be sent to isSelectionValid to determine if its valid // if selection is valid send it bac to getCurrencySelection // if it is false then it is returned to getCurrencySelection and prompted to // make another selection until the selection is valid, then it is returned to main. { /**** i'm not sure if this is what you mean, all i am doing is making sure that their selection is A-H *****/ if(selection=='A' || selection=='B' || selection=='C' || selection=='D' || selection=='E' || selection=='F' || selection=='G' || selection=='H' || selection=='I') return true; else return false; } double calcExchangeAmt (float amtExchanged,char selection) // function calculates the amount of money to be exchanged { switch (toupper(selection)) { case 'A': newAmount =(russianRubles) * (amtExchanged); break; case 'B': newAmount = (northKoreanWon) * (amtExchanged); break; case 'C': newAmount = (chineseYuan) * (amtExchanged); break; case 'D': newAmount = (canadianDollar) * (amtExchanged); break; case 'E': newAmount = (cubanPeso) * (amtExchanged); break; case 'F': newAmount = (ethiopianBirr) * (amtExchanged); break; case 'G': newAmount = (egyptianPound) * (amtExchanged); break; case 'H': newAmount = (tunisianDinar) * (amtExchanged); break; case 'I': newAmount = (thaiBaht) * (amtExchanged); break; } return newAmount; } void displayResults(double newAmount, float amtExchanged, char selection, char yesNo) // displays results and asked to repeat. IF they want to repeat it clears the screen and starts over. { switch(toupper(selection)) { case 'A': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Russian Rubles."<<endl<<endl; break; case 'B': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" North Korean Won."<<endl<<endl; break; case 'C': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Chinese Yuan."<<endl<<endl; break; case 'D': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Cuban Pesos."<<endl<<endl; break; case 'E': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Ethiopian Birr."<<endl<<endl; break; case 'F': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Thai Baht."<<endl<<endl; break; case 'G': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Canadian Dollars."<<endl<<endl; break; case 'H': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Tunisian Dinar."<<endl<<endl; break; case 'I': cout<<"$"<<amtExchanged<<" is "<<newAmount<<" Egyptian Pound."<<endl<<endl; break; } cout<<"Do you wish to continue? (Y for Yes / N for No)"; cin>>yesNo; if(yesNo=='y' || yesNo=='Y') { getDollarAmt(); } else { system("cls"); } }

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  • Programme d'étude sur le C++ bas niveau n° 3 : la Pile, un article d'Alex Darby traduit par ram-0000

    L'objectif de cette série d'articles d'Alex Darby sur la programmation « bas-niveau » est de permettre aux développeurs ayant déjà des connaissances de la programmation C++ de mieux comprendre comment ses programmes sont exécutés en pratique. Ce troisième article explique le rôle et le fonctionnement de la Pile, son usage lors de l'appel d'une fonction, la gestion des variables locales ainsi que la gestion de la valeur de retour d'une fonction. Programme d'étude sur le C++ bas niveau n° 3 : la Pile Connaissiez-vous bien le fonctionnement de la Pile et des appels de fonctions ?

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  • Coherence Based WebLogic Server Session Management

    - by [email protected]
    Specifications Supported Configurations WebLogic Server 10.3.2( or 10.3.1 ) Coherence 3.5.2/463 If you use other verion above, then please check the following matrix:   WebLogic Server 9.2 MP1 Weblogic Server 10.3 WebLogic Smart Update Patch ID: AJQB Patch ID: 6W2W Minimum Coherence Release Level/MetaLink Patch ID 3.4.2 Patch 2-Patch ID:8429415 3.4.2 Patch6-Patch ID:11399293 Environment Variables %COHERENCE_HOME%: coherence installation directory %DOMAIN_HOME%: weblogic domain foler. Instructions We Will create to weblogic domains: domain_a, domain_b. To configure those domains with coherence-based session management . Then the changings of session variable value in one domain will propagate to another domain. Main Steps WebLogic Server create domain_a The process is ignored copy %COHERENCE_HOME%\lib\coherence.jar to %DOMAIN_HOME%\lib startup domain deploy %COHERENCE_HOME%\lib\coherence-web-spi.war as a Shared Library repeat step 1~4 at domain_b Coherence duplicate %COHERENCE_HOME%\bin\cache-server.cmd at the same folder and rename it to web-cache-server.cmd modify web-cache-server.cmd java -server -Xms512m -Xmx512m -cp %coherence_home%/lib/coherence.jar;%coherence_home%/lib/coherence-web-spi.war -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.cacheconfig=WEB-INF/classes/session-cache-config.xml -Dtangosol.coherence.session.localstorage=true com.tangosol.net.DefaultCacheServer startup web-cache-server.cmd Testing develop a web app  with OEPE or JDeveloper and implment functions: changing, viewing, listing  session variables. ( or download sample codes here ) modify weblogic.xml with following content: <?xml version="1.0" encoding="UTF-8"?> <wls:weblogic-web-app xmlns:wls=http://xmlns.oracle.com/weblogic/weblogic-web-app xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://xmlns.oracle.com/weblogic/weblogic-web-app http://xmlns.oracle.com/weblogic/weblogic-web-app/1.0/weblogic-web-app.xsd"> <wls:weblogic-version>10.3.2</wls:weblogic-version> <wls:context-root>CoherenceWeb</wls:context-root> <wls:library-ref> <wls:library-name>coherence-web-spi</wls:library-name> <wls:specification-version>1.0.0.0</wls:specification-version> <wls:exact-match>true</wls:exact-match> </wls:library-ref> </wls:weblogic-web-app> deploy the web app to domain_a and domain_b change session varaible vlaue at domain_a and check whethe if changed at domain_b References Using Oracle Coherence*Web 3.4.2 with Oracle WebLogic Server 10gR3 Oracle Coherence*Web 3.4.2 with Oracle WebLogic Server 10gR3

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  • Improving CSS With .LESS

    Improve your CSS skills using .LESS, a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mix-ins, and nested rules.

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  • Improving CSS With .LESS

    Cascading Style Sheets, or CSS, is a syntax used to describe the look and feel of the elements in a web page. CSS allows a web developer to separate the document content - the HTML, text, and images - from the presentation of that content. Such separation makes the markup in a page easier to read, understand, and update; it can result in reduced bandwidth as the style information can be specified in a separate file and cached by the browser; and makes site-wide changes easier to apply. For a great example of the flexibility and power of CSS, check out CSS Zen Garden. This website has a single page with fixed markup, but allows web developers from around the world to submit CSS rules to define alternate presentation information. Unfortunately, certain aspects of CSS's syntax leave a bit to be desired. Many style sheets include repeated styling information because CSS does not allow the use of variables. Such repetition makes the resulting style sheet lengthier and harder to read; it results in more rules that need to be changed when the website is redesigned to use a new primary color. Specifying inherited CSS rules, such as indicating that a elements (i.e., hyperlinks) in h1 elements should not be underlined, requires creating a single selector name, like h1 a. Ideally, CSS would allow for nested rules, enabling you to define the a rules directly within the h1 rules. .LESS is a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mixins, and nested rules. Behind the scenes, .LESS converts the enhanced CSS rules into standard CSS rules. This conversion can happen automatically and on-demand through the use of an HTTP Handler, or done manually as part of the build process. Moreover, .LESS can be configured to automatically minify the resulting CSS, saving bandwidth and making the end user's experience a snappier one. This article shows how to get started using .LESS in your ASP.NET websites. Read on to learn more! Read More >

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  • Improving CSS With .LESS

    Cascading Style Sheets, or CSS, is a syntax used to describe the look and feel of the elements in a web page. CSS allows a web developer to separate the document content - the HTML, text, and images - from the presentation of that content. Such separation makes the markup in a page easier to read, understand, and update; it can result in reduced bandwidth as the style information can be specified in a separate file and cached by the browser; and makes site-wide changes easier to apply. For a great example of the flexibility and power of CSS, check out CSS Zen Garden. This website has a single page with fixed markup, but allows web developers from around the world to submit CSS rules to define alternate presentation information. Unfortunately, certain aspects of CSS's syntax leave a bit to be desired. Many style sheets include repeated styling information because CSS does not allow the use of variables. Such repetition makes the resulting style sheet lengthier and harder to read; it results in more rules that need to be changed when the website is redesigned to use a new primary color. Specifying inherited CSS rules, such as indicating that a elements (i.e., hyperlinks) in h1 elements should not be underlined, requires creating a single selector name, like h1 a. Ideally, CSS would allow for nested rules, enabling you to define the a rules directly within the h1 rules. .LESS is a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mixins, and nested rules. Behind the scenes, .LESS converts the enhanced CSS rules into standard CSS rules. This conversion can happen automatically and on-demand through the use of an HTTP Handler, or done manually as part of the build process. Moreover, .LESS can be configured to automatically minify the resulting CSS, saving bandwidth and making the end user's experience a snappier one. This article shows how to get started using .LESS in your ASP.NET websites. Read on to learn more! Read More >

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  • jBullet Collision/Physics not working correctly

    - by Kenneth Bray
    Below is the code for one of my objects in the game I am creating (yes although this is a cube, I am not making anything remotely like MineCraft), and my issue is I while the cube will display and is does follow the physics if the cube falls, it does not interact with any other objects in the game. If I was to have multiple cubes in screen at once they all just sit there, or shoot off in all directions never stopping. Anyway, I am new to jBullet, and any help would be appreciated. package Object; import static org.lwjgl.opengl.GL11.GL_QUADS; import static org.lwjgl.opengl.GL11.glBegin; import static org.lwjgl.opengl.GL11.glColor3f; import static org.lwjgl.opengl.GL11.glEnd; import static org.lwjgl.opengl.GL11.glPopMatrix; import static org.lwjgl.opengl.GL11.glPushMatrix; import static org.lwjgl.opengl.GL11.glVertex3f; import javax.vecmath.Matrix4f; import javax.vecmath.Quat4f; import javax.vecmath.Vector3f; import com.bulletphysics.collision.shapes.BoxShape; import com.bulletphysics.collision.shapes.CollisionShape; import com.bulletphysics.dynamics.RigidBody; import com.bulletphysics.dynamics.RigidBodyConstructionInfo; import com.bulletphysics.linearmath.DefaultMotionState; import com.bulletphysics.linearmath.Transform; public class Cube { // Cube size/shape variables private float size; boolean cubeCollidable; boolean cubeDestroyable; // Position variables - currently this defines the center of the cube private float posX; private float posY; private float posZ; // Rotation variables - should be between 0 and 359, might consider letting rotation go higher though I can't think of a purpose currently private float rotX; private float rotY; private float rotZ; //collision shape is a box shape CollisionShape fallShape; // setup the motion state for the ball DefaultMotionState fallMotionState; Vector3f fallInertia = new Vector3f(0, 1, 0); RigidBodyConstructionInfo fallRigidBodyCI; public RigidBody fallRigidBody; int mass = 1; // Constructor public Cube(float pX, float pY, float pZ, float pSize) { posX = pX; posY = pY; posZ = pZ; size = pSize; rotX = 0; rotY = 0; rotZ = 0; // define the physics based on the values passed in fallShape = new BoxShape(new Vector3f(size, size, size)); fallMotionState = new DefaultMotionState(new Transform(new Matrix4f(new Quat4f(0, 0, 0, 1), new Vector3f(0, 50, 0), 1f))); fallRigidBodyCI = new RigidBodyConstructionInfo(mass, fallMotionState, fallShape, fallInertia); fallRigidBody = new RigidBody(fallRigidBodyCI); } public void Update() { Transform trans = new Transform(); fallRigidBody.getMotionState().getWorldTransform(trans); posY = trans.origin.x; posX = trans.origin.y; posZ = trans.origin.z; } public void Draw() { fallShape.calculateLocalInertia(mass, fallInertia); // center point posX, posY, posZ float radius = size / 2; //top glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,0.0f); // red glVertex3f(posX + radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //bottom glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,1.0f,0.0f); // ?? color glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY - radius, posZ - radius); } glEnd(); glPopMatrix(); //right side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,1.0f); // ?? color glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); //left side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,1.0f); // ?? color glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //front side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,0.0f,1.0f); //blue glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); } glEnd(); glPopMatrix(); //back side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,0.0f); // green glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); } }

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  • Mathematica Programming Language&ndash;An Introduction

    - by JoshReuben
    The Mathematica http://www.wolfram.com/mathematica/ programming model consists of a kernel computation engine (or grid of such engines) and a front-end of notebook instances that communicate with the kernel throughout a session. The programming model of Mathematica is incredibly rich & powerful – besides numeric calculations, it supports symbols (eg Pi, I, E) and control flow logic.   obviously I could use this as a simple calculator: 5 * 10 --> 50 but this language is much more than that!   for example, I could use control flow logic & setup a simple infinite loop: x=1; While [x>0, x=x,x+1] Different brackets have different purposes: square brackets for function arguments:  Cos[x] round brackets for grouping: (1+2)*3 curly brackets for lists: {1,2,3,4} The power of Mathematica (as opposed to say Matlab) is that it gives exact symbolic answers instead of a rounded numeric approximation (unless you request it):   Mathematica lets you define scoped variables (symbols): a=1; b=2; c=a+b --> 5 these variables can contain symbolic values – you can think of these as partially computed functions:   use Clear[x] or Remove[x] to zero or dereference a variable.   To compute a numerical approximation to n significant digits (default n=6), use N[x,n] or the //N prefix: Pi //N -->3.14159 N[Pi,50] --> 3.1415926535897932384626433832795028841971693993751 The kernel uses % to reference the lastcalculation result, %% the 2nd last, %%% the 3rd last etc –> clearer statements: eg instead of: Sqrt[Pi+Sqrt[Sqrt[Pi+Sqrt[Pi]]] do: Sqrt[Pi]; Sqrt[Pi+%]; Sqrt[Pi+%] The help system supports wildcards, so I can search for functions like so: ?Inv* Mathematica supports some very powerful programming constructs and a rich function library that allow you to do things that you would have to write allot of code for in a language like C++.   the Factor function – factorization: Factor[x^3 – 6*x^2 +11x – 6] --> (-3+x) (-2+x) (-1+x)   the Solve function – find the roots of an equation: Solve[x^3 – 2x + 1 == 0] -->   the Expand function – express (1+x)^10 in polynomial form: Expand[(1+x)^10] --> 1+10x+45x^2+120x^3+210x^4+252x^5+210x^6+120x^7+45x^8+10x^9+x^10 the Prime function – what is the 1000th prime? Prime[1000] -->7919 Mathematica also has some powerful graphics capabilities:   the Plot function – plot the graph of y=Sin x in a single period: Plot[Sin[x], {x,0,2*Pi}] you can also plot 3D surfaces of functions using Plot3D function

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  • Segfault when iterating over a map<string, string> and drawing its contents using SDL_TTF

    - by Michael Stahre
    I'm not entirely sure this question belongs on gamedev.stackexchange, but I'm technically working on a game and working with SDL, so it might not be entirely offtopic. I've written a class called DebugText. The point of the class is to have a nice way of printing values of variables to the game screen. The idea is to call SetDebugText() with the variables in question every time they change or, as is currently the case, every time the game's Update() is called. The issue is that when iterating over the map that contains my variables and their latest updated values, I get segfaults. See the comments in DrawDebugText() below, it specifies where the error happens. I've tried splitting the calls to it-first and it-second into separate lines and found that the problem doesn't always happen when calling it-first. It alters between it-first and it-second. I can't find a pattern. It doesn't fail on every call to DrawDebugText() either. It might fail on the third time DrawDebugText() is called, or it might fail on the fourth. Class header: #ifndef CLIENT_DEBUGTEXT_H #define CLIENT_DEBUGTEXT_H #include <Map> #include <Math.h> #include <sstream> #include <SDL.h> #include <SDL_ttf.h> #include "vector2.h" using std::string; using std::stringstream; using std::map; using std::pair; using game::Vector2; namespace game { class DebugText { private: TTF_Font* debug_text_font; map<string, string>* debug_text_list; public: void SetDebugText(string var, bool value); void SetDebugText(string var, float value); void SetDebugText(string var, int value); void SetDebugText(string var, Vector2 value); void SetDebugText(string var, string value); int DrawDebugText(SDL_Surface*, SDL_Rect*); void InitDebugText(); void Clear(); }; } #endif Class source file: #include "debugtext.h" namespace game { // Copypasta function for handling the toString conversion template <class T> inline string to_string (const T& t) { stringstream ss (stringstream::in | stringstream::out); ss << t; return ss.str(); } // Initializes SDL_TTF and sets its font void DebugText::InitDebugText() { if(TTF_WasInit()) TTF_Quit(); TTF_Init(); debug_text_font = TTF_OpenFont("LiberationSans-Regular.ttf", 16); TTF_SetFontStyle(debug_text_font, TTF_STYLE_NORMAL); } // Iterates over the current debug_text_list and draws every element on the screen. // After drawing with SDL you need to get a rect specifying the area on the screen that was changed and tell SDL that this part of the screen needs to be updated. this is done in the game's Draw() function // This function sets rects_to_update to the new list of rects provided by all of the surfaces and returns the number of rects in the list. These two parameters are used in Draw() when calling on SDL_UpdateRects(), which takes an SDL_Rect* and a list length int DebugText::DrawDebugText(SDL_Surface* screen, SDL_Rect* rects_to_update) { if(debug_text_list == NULL) return 0; if(!TTF_WasInit()) InitDebugText(); rects_to_update = NULL; // Specifying the font color SDL_Color font_color = {0xff, 0x00, 0x00, 0x00}; // r, g, b, unused int row_count = 0; string line; // The iterator variable map<string, string>::iterator it; // Gets the iterator and iterates over it for(it = debug_text_list->begin(); it != debug_text_list->end(); it++) { // Takes the first value (the name of the variable) and the second value (the value of the parameter in string form) //---------THIS LINE GIVES ME SEGFAULTS----- line = it->first + ": " + it->second; //------------------------------------------ // Creates a surface with the text on it that in turn can be rendered to the screen itself later SDL_Surface* debug_surface = TTF_RenderText_Solid(debug_text_font, line.c_str(), font_color); if(debug_surface == NULL) { // A standard check for errors fprintf(stderr, "Error: %s", TTF_GetError()); return NULL; } else { // If SDL_TTF did its job right, then we now set a destination rect row_count++; SDL_Rect dstrect = {5, 5, 0, 0}; // x, y, w, h dstrect.x = 20; dstrect.y = 20*row_count; // Draws the surface with the text on it to the screen int res = SDL_BlitSurface(debug_surface,NULL,screen,&dstrect); if(res != 0) { //Just an error check fprintf(stderr, "Error: %s", SDL_GetError()); return NULL; } // Creates a new rect to specify the area that needs to be updated with SDL_Rect* new_rect_to_update = (SDL_Rect*) malloc(sizeof(SDL_Rect)); new_rect_to_update->h = debug_surface->h; new_rect_to_update->w = debug_surface->w; new_rect_to_update->x = dstrect.x; new_rect_to_update->y = dstrect.y; // Just freeing the surface since it isn't necessary anymore SDL_FreeSurface(debug_surface); // Creates a new list of rects with room for the new rect SDL_Rect* newtemp = (SDL_Rect*) malloc(row_count*sizeof(SDL_Rect)); // Copies the data from the old list of rects to the new one memcpy(newtemp, rects_to_update, (row_count-1)*sizeof(SDL_Rect)); // Adds the new rect to the new list newtemp[row_count-1] = *new_rect_to_update; // Frees the memory used by the old list free(rects_to_update); // And finally redirects the pointer to the old list to the new list rects_to_update = newtemp; newtemp = NULL; } } // When the entire map has been iterated over, return the number of lines that were drawn, ie. the number of rects in the returned rect list return row_count; } // The SetDebugText used by all the SetDebugText overloads // Takes two strings, inserts them into the map as a pair void DebugText::SetDebugText(string var, string value) { if (debug_text_list == NULL) { debug_text_list = new map<string, string>(); } debug_text_list->erase(var); debug_text_list->insert(pair<string, string>(var, value)); } // Writes the bool to a string and calls SetDebugText(string, string) void DebugText::SetDebugText(string var, bool value) { string result; if (value) result = "True"; else result = "False"; SetDebugText(var, result); } // Does the same thing, but uses to_string() to convert the float void DebugText::SetDebugText(string var, float value) { SetDebugText(var, to_string(value)); } // Same as above, but int void DebugText::SetDebugText(string var, int value) { SetDebugText(var, to_string(value)); } // Vector2 is a struct of my own making. It contains the two float vars x and y void DebugText::SetDebugText(string var, Vector2 value) { SetDebugText(var + ".x", to_string(value.x)); SetDebugText(var + ".y", to_string(value.y)); } // Empties the list. I don't actually use this in my code. Shame on me for writing something I don't use. void DebugText::Clear() { if(debug_text_list != NULL) debug_text_list->clear(); } }

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  • Loading class instance from XML with Texture2D

    - by Thegluestickman
    I'm having trouble with XML and XNA. I want to be able to load weapon settings through XML to make my weapons easier to make and to have less code in the actual project file. So I started out making a basic XML document, something to just assign variables with. But no matter what I changed it gave me a new error every time. The code below gives me a "XML element 'Tag' not found", I added and it started to say the variables weren't found. What I wanted to do in the XML file as well, was load a texture for the file too. So I created a static class to hold my texture values, then in the Texture tag of my XML document I would set it to that instance too. I think that's were the problems are occuring because that's where the "XML element 'Tag' not found" error is pointing me too. My XML document: <XnaContent> <Asset Type="ConversationEngine.Weapon"> <weaponStrength>0</weaponStrength> <damageModifiers>0</damageModifiers> <speed>0</speed> <magicDefense>0</magicDefense> <description>0</description> <identifier>0</identifier> <weaponTexture>LoadWeaponTextures.ironSword</weaponTexture> </Asset> </XnaContent> My Class to load the weapon XML: public class Weapon { public int weaponStrength; public int damageModifiers; public int speed; public int magicDefense; public string description; public string identifier; public Texture2D weaponTexture; } public static class LoadWeaponXML { static Weapon Weapons; public static Weapon WeaponLoad(ContentManager content, int id) { Weapons = content.Load<Weapon>(@"Weapons/" + id); return Weapons; } } public static class LoadWeaponTextures { public static Texture2D ironSword; public static void TextureLoad(ContentManager content) { ironSword = content.Load<Texture2D>("Sword"); } } I'm not entirely sure if you can load textures through XML, but any help would be greatly appreciated.

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  • Thread placement policies on NUMA systems - update

    - by Dave
    In a prior blog entry I noted that Solaris used a "maximum dispersal" placement policy to assign nascent threads to their initial processors. The general idea is that threads should be placed as far away from each other as possible in the resource topology in order to reduce resource contention between concurrently running threads. This policy assumes that resource contention -- pipelines, memory channel contention, destructive interference in the shared caches, etc -- will likely outweigh (a) any potential communication benefits we might achieve by packing our threads more densely onto a subset of the NUMA nodes, and (b) benefits of NUMA affinity between memory allocated by one thread and accessed by other threads. We want our threads spread widely over the system and not packed together. Conceptually, when placing a new thread, the kernel picks the least loaded node NUMA node (the node with lowest aggregate load average), and then the least loaded core on that node, etc. Furthermore, the kernel places threads onto resources -- sockets, cores, pipelines, etc -- without regard to the thread's process membership. That is, initial placement is process-agnostic. Keep reading, though. This description is incorrect. On Solaris 10 on a SPARC T5440 with 4 x T2+ NUMA nodes, if the system is otherwise unloaded and we launch a process that creates 20 compute-bound concurrent threads, then typically we'll see a perfect balance with 5 threads on each node. We see similar behavior on an 8-node x86 x4800 system, where each node has 8 cores and each core is 2-way hyperthreaded. So far so good; this behavior seems in agreement with the policy I described in the 1st paragraph. I recently tried the same experiment on a 4-node T4-4 running Solaris 11. Both the T5440 and T4-4 are 4-node systems that expose 256 logical thread contexts. To my surprise, all 20 threads were placed onto just one NUMA node while the other 3 nodes remained completely idle. I checked the usual suspects such as processor sets inadvertently left around by colleagues, processors left offline, and power management policies, but the system was configured normally. I then launched multiple concurrent instances of the process, and, interestingly, all the threads from the 1st process landed on one node, all the threads from the 2nd process landed on another node, and so on. This happened even if I interleaved thread creating between the processes, so I was relatively sure the effect didn't related to thread creation time, but rather that placement was a function of process membership. I this point I consulted the Solaris sources and talked with folks in the Solaris group. The new Solaris 11 behavior is intentional. The kernel is no longer using a simple maximum dispersal policy, and thread placement is process membership-aware. Now, even if other nodes are completely unloaded, the kernel will still try to pack new threads onto the home lgroup (socket) of the primordial thread until the load average of that node reaches 50%, after which it will pick the next least loaded node as the process's new favorite node for placement. On the T4-4 we have 64 logical thread contexts (strands) per socket (lgroup), so if we launch 48 concurrent threads we will find 32 placed on one node and 16 on some other node. If we launch 64 threads we'll find 32 and 32. That means we can end up with our threads clustered on a small subset of the nodes in a way that's quite different that what we've seen on Solaris 10. So we have a policy that allows process-aware packing but reverts to spreading threads onto other nodes if a node becomes too saturated. It turns out this policy was enabled in Solaris 10, but certain bugs suppressed the mixed packing/spreading behavior. There are configuration variables in /etc/system that allow us to dial the affinity between nascent threads and their primordial thread up and down: see lgrp_expand_proc_thresh, specifically. In the OpenSolaris source code the key routine is mpo_update_tunables(). This method reads the /etc/system variables and sets up some global variables that will subsequently be used by the dispatcher, which calls lgrp_choose() in lgrp.c to place nascent threads. Lgrp_expand_proc_thresh controls how loaded an lgroup must be before we'll consider homing a process's threads to another lgroup. Tune this value lower to have it spread your process's threads out more. To recap, the 'new' policy is as follows. Threads from the same process are packed onto a subset of the strands of a socket (50% for T-series). Once that socket reaches the 50% threshold the kernel then picks another preferred socket for that process. Threads from unrelated processes are spread across sockets. More precisely, different processes may have different preferred sockets (lgroups). Beware that I've simplified and elided details for the purposes of explication. The truth is in the code. Remarks: It's worth noting that initial thread placement is just that. If there's a gross imbalance between the load on different nodes then the kernel will migrate threads to achieve a better and more even distribution over the set of available nodes. Once a thread runs and gains some affinity for a node, however, it becomes "stickier" under the assumption that the thread has residual cache residency on that node, and that memory allocated by that thread resides on that node given the default "first-touch" page-level NUMA allocation policy. Exactly how the various policies interact and which have precedence under what circumstances could the topic of a future blog entry. The scheduler is work-conserving. The x4800 mentioned above is an interesting system. Each of the 8 sockets houses an Intel 7500-series processor. Each processor has 3 coherent QPI links and the system is arranged as a glueless 8-socket twisted ladder "mobius" topology. Nodes are either 1 or 2 hops distant over the QPI links. As an aside the mapping of logical CPUIDs to physical resources is rather interesting on Solaris/x4800. On SPARC/Solaris the CPUID layout is strictly geographic, with the highest order bits identifying the socket, the next lower bits identifying the core within that socket, following by the pipeline (if present) and finally the logical thread context ("strand") on the core. But on Solaris on the x4800 the CPUID layout is as follows. [6:6] identifies the hyperthread on a core; bits [5:3] identify the socket, or package in Intel terminology; bits [2:0] identify the core within a socket. Such low-level details should be of interest only if you're binding threads -- a bad idea, the kernel typically handles placement best -- or if you're writing NUMA-aware code that's aware of the ambient placement and makes decisions accordingly. Solaris introduced the so-called critical-threads mechanism, which is expressed by putting a thread into the FX scheduling class at priority 60. The critical-threads mechanism applies to placement on cores, not on sockets, however. That is, it's an intra-socket policy, not an inter-socket policy. Solaris 11 introduces the Power Aware Dispatcher (PAD) which packs threads instead of spreading them out in an attempt to be able to keep sockets or cores at lower power levels. Maximum dispersal may be good for performance but is anathema to power management. PAD is off by default, but power management polices constitute yet another confounding factor with respect to scheduling and dispatching. If your threads communicate heavily -- one thread reads cache lines last written by some other thread -- then the new dense packing policy may improve performance by reducing traffic on the coherent interconnect. On the other hand if your threads in your process communicate rarely, then it's possible the new packing policy might result on contention on shared computing resources. Unfortunately there's no simple litmus test that says whether packing or spreading is optimal in a given situation. The answer varies by system load, application, number of threads, and platform hardware characteristics. Currently we don't have the necessary tools and sensoria to decide at runtime, so we're reduced to an empirical approach where we run trials and try to decide on a placement policy. The situation is quite frustrating. Relatedly, it's often hard to determine just the right level of concurrency to optimize throughput. (Understanding constructive vs destructive interference in the shared caches would be a good start. We could augment the lines with a small tag field indicating which strand last installed or accessed a line. Given that, we could augment the CPU with performance counters for misses where a thread evicts a line it installed vs misses where a thread displaces a line installed by some other thread.)

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