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• Python: Removing particular character (u"\u2610") from string

  - by duhaime

  I have been wrestling with decoding and encoding in Python, and I can't quite figure out how to resolve my problem. I am looping over xml text files (sample) that are apparently coded in utf-8, using Beautiful Soup to parse each file, then looking to see if any sentence in the file contains one or more words from two different list of words. Because the xml files are from the eighteenth century, I need to retain the em dashes that are in the xml. The code below does this just fine, but it also retains a pesky box character that I wish to remove. I believe the box character is this character. (You can find an example of the character I wish to remove in line 3682 of the sample file above. On this webpage, the character looks like an 'or' pipe, but when I read the xml file in Komodo, it looks like a box. When I try to copy and paste the box into a search engine, it looks like an 'or' pipe. When I print to console, though, the character looks like an empty box.) To sum up, the code below runs without errors, but it prints the empty box character that I would like to remove. for work in glob.glob(pathtofiles): openfile = open(work) readfile = openfile.read() stringfile = str(readfile) decodefile = stringfile.decode('utf-8', 'strict') #is this the dodgy line? soup = BeautifulSoup(decodefile) textwithtags = soup.findAll('text') textwithtagsasstring = str(textwithtags) #this method strips everything between anglebrackets as it should textwithouttags = stripTags(textwithtagsasstring) #clean text nonewlines = textwithouttags.replace("\n", " ") noextrawhitespace = re.sub(' +',' ', nonewlines) print noextrawhitespace #the boxes appear I tried to remove the boxes by using noboxes = noextrawhitespace.replace(u"\u2610", "") But Python threw an error flag: UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 280: ordinal not in range(128) Does anyone know how I can remove the boxes from the xml files? I would be grateful for any help others can offer.

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• C# Dictionary Loop Enhancment

  - by Toto

  Hi, I have a dictionary with around 1 milions items. I am constantly looping throw the dictionnary : public void DoAllJobs() { foreach (KeyValuePair<uint, BusinessObject> p in _dictionnary) { if(p.Value.MustDoJob) p.Value.DoJob(); } } The execution is a bit long, around 600 ms, I would like to deacrese it. Here is the contraints : MustDoJob values mostly stay the same beetween two calls to DoAllJobs() 60-70% of the MustDoJob values == false From time to times MustDoJob change for 200 000 pairs. Some p.Value.DoJob() can not be computed at the same time (COM object call) Here, I do not need the key part of the _dictionnary objet but I really do need it somewhere else I wanted to do the following : Parallelizes but I am not sure is going to be effective due to 4. Sorts the dictionnary since 1. and 2. (and stop want I find the first MustDoJob == false) but I am wondering what 3. would result in I did not implement any of the previous ideas since it could be a lot of job and I would like to investigate others options before. So...any ideas ?

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• How to output multiple rows from an SQL query using the mysqli object

  - by Jonathan

  Assuming that the mysqli object is already instantiatied (and connected) with the global variable $mysql, here is the code I am trying to work with. class Listing { private $mysql; function getListingInfo($l_id = "", $category = "", $subcategory = "", $username = "", $status = "active") { $condition = "`status` = '$status'"; if (!empty($l_id)) $condition .= "AND `L_ID` = '$l_id'"; if (!empty($category)) $condition .= "AND `category` = '$category'"; if (!empty($subcategory)) $condition .= "AND `subcategory` = '$subcategory'"; if (!empty($username)) $condition .= "AND `username` = '$username'"; $result = $this->mysql->query("SELECT * FROM listing WHERE $condition") or die('Error fetching values'); $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; return $info; } } there are several hundred listings in the db and when I call $result-fetch_array() it places in an array the first row in the db. however when I try to call the object, I can't seem to access more than the first row. for instance: $listing_row = new Listing; while ($listing = $listing_row-getListingInfo()) { echo $listing[0]; } this outputs an infinite loop of the same row in the db. Why does it not advance to the next row? if I move the code: $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; if I move this outside the class, it works exactly as expected outputting a row at a time while looping through the while statement. Is there a way to write this so that I can keep the fetch_array() call in the class and still loop through the records?

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• What is the n in O(n) when comparing sorting algorithms?

  - by Mumfi

  The question is rather simple, but I just can't find a good enough answer. I've taken a look at the most upvoted question regarding the Big-Oh notation, namely this: Plain English explanation of Big O It says there that: For example, sorting algorithms are typically compared based on comparison operations (comparing two nodes to determine their relative ordering). Now let's consider the simple bubble sort algorithm: for (int i = arr.length - 1; i > 0 ; i--) { for (int j = 0; j<i; j++) { if (arr[j] > arr[j+1]) { switchPlaces(...) } } } I know that worst case is O(n^2) and best case is O(n), but what is n exactly? If we attempt to sort an already sorted algorithm (best case), we would end up doing nothing, so why is it still O(n)? We are looping through 2 for-loops still, so if anything it should be O(n^2). n can't be the number of comparison operations, because we still compare all the elements, right? This confuses me, and I appreciate if someone could help me.

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• Retrieve E-mail from server (pop3) by date for filtering on subject or body in C#

  - by Josh

  I have a piece of monitoring software I am writing which needs to retrieve e-mails sent to an address for a certain day so that I can filter them by a regex in the subject or body. I don't need to retrieve the entire message, only the subject and body for all messages on a given day so that I can evaluate them with a regular expression for a token. I looked at EAGetMail as a solution, but their implementation doesn't do what I need to to do. I can only get all information on mail, which only has the size and index. I would need it by subject, but even then I don't want to get everything in inbox. If I went with this solution I have to get all mail, and then retrieve each mail message individually to evaluate the subject and body. This is not ideal. I also looked at OpenPop.Net, but it too does not have a targeted retrieval for today's messages only. Can I even do what I want without looping through every single email on the server until I find a match? What is the best way to accomplish what I am trying to do? Am I going to have to build a custom web request to get the data I want? Also, I looked at Chilkat, but I am looking for a free solution, even if it means building the http request myself.

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• How to efficiently get highest & lowest values from a List<double?>, and then modify them?

  - by DaveDev

  I have to get the sum of a list of doubles. If the sum is 100, I have to decrement from the highest number until it's = 100. If the sum is < 100, I have to increment the lowest number until it's = 100. I can do this by looping though the list, assigning the values to placeholder variables and testing which is higher or lower but I'm wondering if any gurus out there could suggest a super cool & efficient way to do this? The code below basically outlines what I'm trying to achieve: var splitValues = new List<double?>(); splitValues.Add(Math.Round(assetSplit.EquityTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.PropertyTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.FixedInterestTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.CashTypeSplit() ?? 0)); var listSum = splitValues.Sum(split => split.Value); if (listSum != 100) { if (listSum > 100) { // how to get highest value and decrement by 1 until listSum == 100 // then reassign back into the splitValues list? var highest = // ?? } else { // how to get lowest where value is > 0, and increment by 1 until listSum == 100 // then reassign back into the splitValues list? var lowest = // ?? } } update: the list has to remain in the same order as the items are added.

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• php:: apply backticks to first word in sentence

  - by Hailwood

  Hi guys, basically what I am trying to do is, I have an array that looks something like this: array( array( 'select' =>'first string', 'escape' => true ), array( 'select' =>'second', 'escape' => true ), array( 'select' =>'the third string', 'escape' => true ), array( 'select' =>'fourth string', 'escape' => false ), ) I am looping over it and I want to end up with this output array( array( 'select' =>'`first` string', 'escape' => true ), array( 'select' =>'`second`', 'escape' => true ), array( 'select' =>'`the` third string', 'escape' => true ), array( 'select' =>'fourth string', 'escape' => false ), ) so basic rules are backticks are only applied if escape is true backticks are only applied to the first word in a sentence if there is only one word backticks are applied to the word My plan was to use if($item['escape']) { $pos = (strpos($item['select'], ' ') === false ? strlen($item['select']) : strpos($item['select'], ' ')); $item['select'] = '`' . substr($item['select'], 0, $pos) . '`' . substr($item['select'], $pos, strlen($item['select'])); } but the $item['select'] = line seems rather long winded, is there a better way to write it?

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• Why is my SAX handler returning an object with no values? I am setting it just fine

  - by Blankman

  I'm writing a SAX parser for an xml, and the object it returns doesn't have the values that I am setting in the events. My classes structure is like this: public class ProductSAXHandler extends DefaultHandler { private Product product; public ProductSAXHandler() { product = new Product(); } public Product ParseXmlFile(String xml) { SAXParserFactory spf = new ... XMLReader parser = .... parser.parse(xml); return product; } public void StartElement(....) { for(int ...) { // looping through attributes if(qName == "description" && name == "sku") { product.setSKU(value); } } } } When I am in debug mode, the value of product does get set, and I can see that the product's sku field has the correct value. But for some reason the product object returned is just a new Product object with no values set during the parsing. What am I doing wrong here? It must be me not understanding how these events are fired etc.

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• What's up with this reversing bit order function?

  - by MattyW

  I'm rather ashamed to admit that I don't know as much about bits and bit manipulation as I probably should. I tried to fix that this weekend by writing some 'reverse the order of bits' and 'count the ON bits' functions. I took an example from here but when I implemented it as below, I found I had to be looping while < 29. If I loop while < 32 (as in the example) Then when I try to print the integer (using a printBits function i've written) I seem to be missing the first 3 bits. This makes no sense to me, can someone help me out? int reverse(int n) { int r = 0; int i = 0; for(i = 0; i < 29; i++) { r = (r << 1) + (n & 1); n >>=1; } return r; }

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• Ruby on Rails: temporarily update an attribute into cache without saving it?

  - by randombits

  I have a bit of code that depicts this hypothetical setup below. A class Foo which contains many Bars. Bar belongs to one and only one Foo. At some point, Foo can do a finite loop that lapses 2+ iterations. In that loop, something like the following happens: bar = Bar.find_where_in_use_is_zero bar.in_use = 1 Basically what find_where_in_use_is_zero does something like this in as far as SQL goes: SELECT * from bars WHERE in_use = 0 Now the problem I'm facing is that I cannot run the following line of code after bar.in_use =1 is invoked: bar.save The reason is clear, I'm still looping and the new Foo hasn't been created, so we don't have a foo_id to put into bars.foo_id. Even if I set to allow foo_id to be NULL, we have a problem where one of the bars can fail validation and the existing one was saved to the database. In my application, that doesn't work. The entire request is atomic, either all succeeds or fails together. What happens next, is that in my loop, I have the potential to select the same exact bar that I did on a previous iteration of the loop since the in_use flag will not be set to 1 until @foo.save is called. Is there anyway to work around this condition and temporarily set the in_use attribute to 1 for subsequent iterations of the loop so that I retrieve an available bar instance?

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• C++ Segmentation Fault when Iterating through a Vector

  - by user1790374

  I have a program that maintains an integer vector. I have three functions that add an integer, remove an integer and check whether an integer is already in the vector. The problem is with the last one. vector<int> children; void CtpTestingApplication::addChild(int child) { for (int i=0; i<children.size(); i++) { //already a child if (children[i]==child) return; } //child not yet recorded children.push_back(child); received.push_back(false); cout<<"added child "<<child; } void CtpTestingApplication::removeChild(int child) { Enter_Method("removeChild"); for (int i=0; i<children.size(); i++) { //already a child, remove it if (children[i]==child) { children.erase(children.begin()+i); received.erase(received.begin()+i); cout<<"removed child "<<child; } } //not recorded, no need to remove } bool CtpTestingApplication::isChild(int child) { Enter_Method("isChild"); vector<int>::iterator ic; bool result = false; for (ic= children.begin(); ic < children.end(); ic++) { cout<<*ic<<" vs "<<child; // if (child==*ic) result = true; } return result; } I always get segmentation fault when I uncomment "if (child==*ic)", even though printouts show that the vector is not empty and contains the expected integers. For example, with the if statements commented, I can see 1 vs 4, 2 vs 4, 4 vs 4, 12 vs 4 I also attempted looping using children[i] and so on, but to no avail. Any help would be appreciated. Thank you.

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• Why are my thread being terminated ?

  - by Sephy

  Hi, I'm trying to repeat calls to methods through 3 differents threads. But after I start my threads, during the next iteration of my loop, they are all terminated so nothing is executed... The code is as follows : public static void main(String[] args) { main = new Main(); pollingThread.start(); } static Thread pollingThread = new Thread() { @Override public void run() { while (isRunning) { main.poll(); // test the state of the threads try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }; }; public void poll() { if (clientThread == null) { clientThread = new Thread(new Runnable() { @Override public void run() { //create some objects } }); clientThread.start(); } else if (clientThread.isAlive()) { // do some treatment } if (gestionnaireThread == null) { gestionnaireThread = new Thread(new Runnable() { @Override public void run() { //create some objects }; }); gestionnaireThread.start(); } else if (gestionnaireThread.isAlive()) { // do some treatment } if (marchandThread == null) { marchandThread = new Thread(new Runnable() { @Override public void run() { // create some objects }; }); marchandThread.start(); } else if (marchandThread.isAlive()) { // do some treatment } } And for some reason, when I test the state of my different threads, they appear as runnable and then a the 2nd iteration, they are all terminated... What am I doing wrong? I actually have no error, but the threads are terminated and so my loop keeps looping and telling me the threads are terminated.... Thanks for any help.

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• GoldenGate 12c - MySQL Active-Active Replication Setup

  - by Jinyu Wang-Oracle

  Active-active  (also called Master-Master or Bi-Directional) replication captures data changes from two or more systems and replicat the changes to synchronize the data.  Active-Active replication is often needed for high availability, load balancing and scaling out purposes.   Oracle GoldenGate is known to be one of the first and the best replication tool handling active-active replications. As of Oracle GoldenGate 12c, it provides (Refer to Oracle GoldenGate 12.1.2 Documentation - Configuring Oracle GoldenGate for Active-Active High Availability for more information) the followings: Robust loop-back prevention Comprehensive conflict resolution and detection support Heterogeneous support across different database versions and operation systems.  Oracle GoldenGate supports active-active configurations for DB2 on z/OS, LUW, and IBM i, MySQL, Oracle, SQL/MX,SQL Server, Sybase, and Teradata. However, the setup is different from database to database. In this example, I will show you how to setup an active-active data replication between two MySQL database instances. The example setup below is to have active-active replication between MySQL 5.5 and MySQL 5.6 instances and is shown as follows: MySQL 5.5 (Manager Port: 15105)  Extract EXTRACT demoex01 SETENV (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.5.38/data/mysql.sock') DBOPTIONS CONNECTIONPORT 3305 DBOPTIONS HOST oraclelinux6.localdomain SOURCEDB test USERID root, PASSWORD mysql EXTTRAIL ./dirdat/extract/de TRANLOGOPTIONS ALTLOGDEST "/home/oracle/software/mysql_5.5.38/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl REPORTROLLOVER AT 05:30 ON saturday TABLE test.TCUSTMER; TABLE test.TCUSTORD; Pump EXTRACT demopm01 RMTHOST localhost, MGRPORT 15106, COMPRESS, TIMEOUT 30 RMTTRAIL ./dirdat/replicat/ps PASSTHRU TABLE test.TCUSTMER; TABLE test.TCUSTORD; Replicat replicat demorp01 setenv (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.5.38/data/mysql.sock') dboptions host oraclelinux6.localdomain, connectionport 3305 targetdb test, userid root, password mysql sourcedefs ./dirdat/replicat/democust.def discardfile ./dirrpt/demprp01.dsc, purge REPERROR (DEFAULT, ABEND) REPERROR(1062, IGNORE) map test.TCUSTMER, target test.TCUSTMER,colmap(usedefaults, region_code="region code"); map test.TCUSTORD, target test.TCUSTORD; MySQL 5.6 (Manager Port: 15106) Replicat replicat demorp01 setenv (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.6.19/data/mysql.sock') dboptions host oraclelinux6.localdomain, connectionport 3306 targetdb test, userid root, password mysql --assumetargetdefs sourcedefs ./dirdat/replicat/democust.def discardfile ./dirrpt/demprp01.dsc, purge map test.TCUSTMER, target test.TCUSTMER, colmap(usedefaults, "region code"=region_code); map test.TCUSTORD, target test.TCUSTORD; Extract EXTRACT demoex01 SETENV (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.6.19/data/mysql.sock') DBOPTIONS CONNECTIONPORT 3306 DBOPTIONS HOST oraclelinux6.localdomain SOURCEDB test USERID root, USERID mysql EXTTRAIL ./dirdat/extract/de TRANLOGOPTIONS ALTLOGDEST "/usr/local/mysql56/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl TABLE test.TCUSTMER; TABLE test.TCUSTORD; Pump EXTRACT demopm01 RMTHOST localhost, MGRPORT 15105, COMPRESS, TIMEOUT 30 RMTTRAIL ./dirdat/replicat/ps PASSTHRU TABLE test.TCUSTMER; TABLE test.TCUSTORD; The setup parameters are quite self-explanatory. The key setup is to avoid the replication data  looping. Oracle GoldenGate for MySQL uses the information in the replication checkpoint table to identify the transaction applied by replicats and thus avoid extracting those transactions by Oracle GoldenGate extracts. The example setup in the extract in MySQL 5.5 instance is shown as follows.  TRANLOGOPTIONS ALTLOGDEST "/home/oracle/software/mysql_5.5.38/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl Setting up an active-active replication is often more complicated than this and requires the following additional considerations. I would elaborate on this in the follow-up discussions. 

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• Let Me Show You Something: Instagram, Vine and Snapchat for Brands

  - by Mike Stiles

  While brands are well aware of how much more impactful images are than text-only posts on social channels, today you’re additionally being presented with platform after additional platform for hosting, doctoring and sharing photos and videos.  Can you play in every sandbox? And if you do, can you be brilliant on all of them? As has usually been the case, so far brands are sticking their toes into new platforms while not actually committing to them, or strategizing for them, or resourcing them. TrackMaven found of the 123 F500 companies using Instagram, only 22% of them are active on it. Likewise, research from Simply Measured found brands are indeed jumping in, with the number establishing a presence on Instagram up 55% over the past year. Users want them there…brand engagement has exploded 350%, and over 1/3 of the top brands have at least 10,000 followers. BUT…the top 10 brands are generating 33% of all posts, reaping 83% of all engagement. Things are also growing on Twitter’s Vine, the 6-second looping video app that hit 40 million users in August. The 7th Chamber says 5 tweets a second contain a Vine link. Other studies say branded Vines are 4 times more likely to be shared and seen than rank-and-file branded videos. Why? Users know that even if a video is pure junk, they won’t get robbed of too much of their valuable time. Vine is always upgrading so you can make sure your videos are worth viewers’ time. You can now edit videos, and save & work on several projects concurrently. What you can’t do is upload a finely crafted video into Vine, but you can do that with Instagram. The key to success? Same as with all other content; make it of value. Deliver a laugh or a lesson or both. How-to, behind the scenes peeks, contests, demos, all make sense in the short video format. Or follow Nash Grier’s example, which is to just have fun with and connect to your viewers, earning their trust that your next Vine will be as good as the last. Nash is only 15, has over 1.4 million followers, and adds about 100,000 a week. He broke out when one of his videos was re-Vined by some other kid with 300,000 followers. Make good stuff, get it in front of influencers, and your brand Vines could break out as well. Then there’s Snapchat, the “this photo will self destruct” platform. How can that be of use to brands besides offering coupons that really expire? The jury is out. But with an audience of over 100 million and a valuation of $800 million, media-with-a-time-limit is compelling. Now there’s “Snapchat Stories” that can last 24 hours and be shared to the public at large. You might be able to capitalize on how much more focus gets put on content when there’s a time limit on its availability. The underlying truth to all of this is, these are all tools. Very cool, feature rich tools, but tools. You can give the exact same art kit to 5 different people and you’d get back 5 very different works, ranging from worthless garbage to masterpiece. Brands are being called upon to be still and moving image artists. That’s what your customers are used to seeing, from a variety of sources. Commit to communicating with them accordingly. @mikestiles Photo: stock.xchng

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• New Sample Demonstrating the Traversing of Tree Bindings

  - by Duncan Mills

  A technique that I seem to use a fair amount, particularly in the construction of dynamic UIs is the use of a ADF Tree Binding to encode a multi-level master-detail relationship which is then expressed in the UI in some kind of looping form – usually a series of nested af:iterators, rather than the conventional tree or treetable. This technique exploits two features of the treebinding. First the fact that an treebinding can return both a collectionModel as well as a treeModel, this collectionModel can be used directly by an iterator. Secondly that the “rows” returned by the collectionModel themselves contain an attribute called .children. This attribute in turn gives access to a collection of all the children of that node which can also be iterated over. Putting this together you can represent the data encoded into a tree binding in all sorts of ways. As an example I’ve put together a very simple sample based on the HT schema and uploaded it to the ADF Sample project. It produces this UI: The important code is shown here for a Region -> Country -> Location Hierachy: <af:iterator id="i1" value="#{bindings.AllRegions.collectionModel}" var="rgn"> <af:showDetailHeader text="#{rgn.RegionName}" disclosed="true" id="sdh1"> <af:iterator id="i2" value="#{rgn.children}" var="cnty">     <af:showDetailHeader text="#{cnty.CountryName}" disclosed="true" id="sdh2">       <af:iterator id="i3" value="#{cnty.children}" var="loc">         <af:panelList id="pl1">         <af:outputText value="#{loc.City}" id="ot3"/>           </af:panelList>         </af:iterator>       </af:showDetailHeader>     </af:iterator>   </af:showDetailHeader> </af:iterator>  You can download the entire sample from here:

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• An observation on .NET loops – foreach, for, while, do-while

  It’s very common that .NET programmers use “foreach” loop for iterating through collections. Following is my observation whilst I was testing simple scenario on loops. “for” loop is 30% faster than “foreach” and “while” loop is 50% faster than “foreach”. “do-while” is bit faster than “while”. Someone may feel that how does it make difference if I’m iterating only 1000 times in a loop. This test case is only for simple iteration. According to the "Data structure" concepts, best and worst cases are completely based on the data we provide to the algorithm. so we can not conclude that a "foreach" algorithm is not good. All I want to tell that we need to be little cautious even choosing the loops. Example:- You might want to chose quick sort when you want to sort more numbers. At the same time bubble sort may be effective than quick sort when you want to sort less numbers. Take a simple scenario, a request of a simple web application fetches the data of 10000 (10K) rows and iterating them for some business logic. Think, this application is being accessed by 1000 (1K) people simultaneously. In this simple scenario you are ending up with 10000000 (10Million or 1 Crore) iterations. below is the test scenario with simple console application to test 100 Million records. using System;using System.Collections.Generic;using System.Diagnostics;namespace ConsoleApplication1{ class Program { static void Main(string[] args) { var sw = new Stopwatch(); var numbers = GetSomeNumbers(); sw.Start(); foreach (var item in numbers) { } sw.Stop(); Console.WriteLine( String.Format("\"foreach\" took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); for (int i = 0; i < numbers.Count; i++) { } sw.Stop(); Console.WriteLine( String.Format("\"for\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); var it = 0; while (it++ < numbers.Count) { } sw.Stop(); Console.WriteLine( String.Format("\"while\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); sw.Reset(); sw.Start(); var it2 = 0; do { } while (it2++ < numbers.Count); sw.Stop(); Console.WriteLine( String.Format("\"do-while\" loop took {0} milliseconds", sw.ElapsedMilliseconds)); } #region Get me 10Crore (100 Million) numbers private static List<int> GetSomeNumbers() { var lstNumbers = new List<int>(); var count = 100000000; for (var i = 1; i <= count; i++) { lstNumbers.Add(i); } return lstNumbers; } #endregion Get me some numbers }} In above example, I was just iterating through 100 Million numbers. You can see the time to execute various  loops provided in .NET Output "foreach" took 1108 milliseconds "for" loop took 727 milliseconds "while" loop took 596 milliseconds "do-while" loop took 594 milliseconds   Press any key to continue . . . So I feel we need to be careful while choosing the looping strategy. Please comment your thoughts. span.fullpost {display:none;}

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• C# Dev Challenge Part 1 of n &ndash; Beginner Edition

  - by mbcrump

  I developed this challenge to test one’s knowledge of C Sharp. I am planning on creating several challenges with different skill sets, so don’t get mad if this challenge doesn’t well challenge you... I noticed that most people like short quizzes so this one only contains 5 questions. All of the challenges are clear and concise of what I am asking you to do. No smoke and mirrors here, meaning that none of the code has syntax errors. The purpose of this exercise is to test several OOP concepts and see how much of the C# language you really know. Question #1 – Lets start off Easy… Will the following code snippet compile successfully? What does this question test? - Can this compile without a namespace? Do you have to have an entry point of “static void Main()”? class Test { static int Main() { System.Console.WriteLine("Developer Challenge"); return 0; } } Answer (select text in box below): Yes, it will compile successfully. Question #2 – What is the value of the Console.WriteLine statements? What does this question test? – Do I understand reference types/value types? If a variable is declared with the @ symbol and its not a reserved keyword does the application compile successfully? using System; internal struct MyStruct { public int Value; } internal class MyClass { public int Value; } class Test { static void Main() { MyStruct @struct1 = new MyStruct(); MyStruct @struct2 = @struct1; @struct2.Value = 100; MyClass @ref1 = new MyClass(); MyClass @ref2 = @ref1; @ref2.Value = 100; Console.WriteLine("Value Type: {0} {1}", @struct1.Value, @struct2.Value); Console.WriteLine("Reference Type: {0} {1}", @ref1.Value, @ref2.Value); } } Answer (select text in box below): Value Type: 0 100 Reference Type: 100 100 Question #3 – What is the value of the Console.WriteLine statements? What does this question test? – Can 2 objects reference the same point in memory? using System; class Test { static void Main() { string s1 = "Testing2"; string t1 = s1; Console.WriteLine(s1 == t1); Console.WriteLine((object)s1 == (object)t1); } } Answer (select text in box below): True True Question #4 – What is the value of the Console.WriteLine statements? What does this question test? – How does the “Stack” work – LIFO or FIFO?   using System; using System.Collections; class Test { static void Main() { Stack a = new Stack(5); a.Push("1"); a.Push("2"); a.Push("3"); a.Push("4"); a.Push("5"); foreach (var o in a) { Console.WriteLine(o); } } } Answer (select text in box below): 5 4 3 2 1 Question #5 – What is the value of the Console.WriteLine statements? What does this question test? – Array and General Looping Knowledge. using System; namespace ConsoleApplication5 { class Program { static void Main(string[] args) { int[] J_LIST = new int[5] { 1, 2, 3, 4, 5 }; int K = 10; int L = 5; foreach (var J in J_LIST) { K = K - J; L = K + 2 * J; Console.WriteLine("J = {0, 5} K = {1, 5} L = {2, 5}", J, K, L); } Console.ReadLine(); } } } Answer (select text in box below): J = 1 K = 9 L = 11 J = 2 K = 7 L = 11 J = 3 K = 4 L = 10 J = 4 K = 0 L = 8 J = 5 K = -5 L = 5 Stay Tuned for more challenges!

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• Taking a look at the Mindscape Phone Elements for WP7.

  - by mbcrump

  I recently heard that Mindscape HQ had released the Windows Phone 7 Controls and had to take a look at them. 100 FREE LICENSE GIVEAWAY! Before we get to the screenshots, you will be pleased to learn that my usergroup called “Allaboutxaml” has partnered with Mindscape HQ and are giving away 100 license. You can check out the site here to get your free controls. But please hurry as after the 100 are gone then I will not have any more to give away! A few links to read first: The official blog post from Mindscape HQ detailing the release. They also have the links to download the trial and get started. The phone elements official forum! So, let’s get started. After you download the controls go ahead and double click the .exe to get started installing them. After everything is installed then you will have the following program group. I’d recommend clicking on the Phone Elements Directory to get started: Let’s go over each element: Bin – Just the .DLL that’s required to use Mindscape HQ WP7 Controls in your project. Documentation – a .CHM File that will show you how to get your project up and running quickly. Resources – Just a few image files Samples – This is a full WP7 project that details every controls. The thing that I was most interested in was how the controls look and is it easy to use. I always believed if your paying for controls then you should hold my hand through using them. You will be pleased to know that Mindscape made it very easy to use. First, the WP7 project in the “Samples” folder just works. Double click on the solution file and you are in an emulator looking at the controls. Since you have the source code for every control, it’s a matter of copying/pasting the code in your project to get it to work. What I did, was play with the controls in the emulator until I found one I could use. Then I looked at the Visual Studio solution and found the Page that contained the control. Mindscape makes this very easy to do with their layout: So, the one that I was interested in was the Looping List Box.  Here is a demo of it: I wanted to see how they were populating the numbers 1-100 so I found the code behind and noticed it was just this one line. LoopingListBox1.DataSource = new NumericDataSource() { MinValue = 1, MaxValue = 100 }; In case you are wondering, the NumericDataSource was created by MindScape and you can view the Declaration to find out more about it:   So, the controls are pretty much that easy to use. Play with the emulator and find the control you want to use. Find the XAML file in the Sample Solution and copy/paste the code. Let’s go ahead and take a look at the controls available: They also have a great variety of Charting controls: Overall it’s a nice set of WP7 controls. Feel free to leave a comment below on anything you would like to see and I will make sure that Mindscape HQ get the message. Don’t forget if you are the first 100 people reading this article then you will get a free license.  Subscribe to my feed CodeProject

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• Windows XP SP3 - Library not registered error... IE8 not installing.

  - by Wesley

  Specs to put things in context: AMD Athlon XP 2400+ @ 1987 MHz / 2 x 512MB PC3200 DDR RAM / WD 160GB IDE HDD / 3DFuzion 128MB GeForce 6200 AGP 4x / FIC AM37 / Windows XP SP3 Just recently, I was unable to start Windows Media Player. I clicked it and the busy cursor came up, but then nothing happened. Also, I tried doing a search for a file, and same thing. It would show busy cursor then suddenly stop doing anything. I couldn't find it in the Processes of the Task Manager. (Perhaps I don't know what I'm looking for?) Also, I was trying to update my DirectX, which has been running something older than DX9 9.0c for a while now, except the installation fails due to "internal error". I think the failed DirectX installation has been like that for a while... (I remember trying to install DX9 9.0c a while back, but still failed.) The Windows programs not starting, I don't think I've ever had before... what could be the cause of these problems?! Thanks in advance. =) EDIT1: Weird thing now is that when I try to open User Accounts, I get a message saying "Wrong number of arguments or invalid property assignment." Also, when I'm trying to open services.msc, I'm getting a script error that says that "Library not registered." (Code: 0, URL: res://C:\WINDOWS\System32\mmcndmgr.dll/views.htm) Perhaps this is related to my other question, where I seemed to have an unregistered library of some sort. EDIT2: The DirectX End-User Runtime Web Installer freakishly worked and updated successfully. Now, I have focussed the question on the bigger problem. For WMP11, H&S, and Search, I click it once, get a busy icon for a second, and then nothing happens. Refer to EDIT1 for other problems. EDIT3: Seems that my problems may be related to some Internet Explorer Script Errors. So what I did was download the IE8 installer from the Microsoft website, but when I run it and get to the main portion of the installer, it just keeps looping on the Downloading step of the installation. The installer is still running, but I left it for at least 4 hours and the downloading step was still not finished. What is the problem? Also, I uninstalled Ubuntu 9.10 after these problems, but they still remain. EDIT4: I'm getting an active desktop recovery background on startup now. And within seconds my computer hangs again. EDIT3 explains main issue though.

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• Setting Timeouts: SQL Server 2008/IIS 7.5

  - by Julie

  We have recently migrated from a Win 2003/SQL Server 2000 system to Win 2008 64 bit R2, SQL Server 2008 R2. Our websites are in classic asp, and this can't be changed to another scripting language at this time. On the old server, if I got stuck in some kind of endless loop, the page would throw an error. On the new server, I have a page that has some sort of looping problem, that even though the SQL SP is called only once (and runs fine run as a query on the server) it pegs SQL server and therefore locks all of our websites. I'll get my code figured out, no biggie. But I need to make sure the server times out when this happens. (The page I'm working on runs fine with certain instances of the query, and locks with others using a different query variable. I can't have something like that sneak up on me on a page I haven't touched for three years.) I can't figure out how an SP that runs once on the server, from an ASP page, is tying up SQL server this way. It's obviously some sort of a timeout issue, but I can't figure out where/which timeout values to change. I actually have to remote desktop to the server and kill the process in SQL server. I'm afraid I'm a generalist, and server management is not my thing, even though it's my responsibility, so I am almost certain to have questions about any answer that I receive. How can I track this down? What settings do I need to change? More info: It's not SQL Server On our test site, I created an ASP file that just did an endless loop (do while 1=1) and had the same problem - the other websites wouldn't load - without SQL server being involved. So I think the reason the process was hanging is that the page wasn't timing out as it should, and so the connection to SQL was never closed. Killing the process in SQL server would reset the page somehow. For my intentional endless loop, I had to refresh the app pool to get rid of it. This points more to either IIS or the ASP settings. The ASP timeouts are set to whatever the default were when the server was first loaded. I still can't figure out why one file is locking up all websites, though. Again, that didn't happen on the old server.

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• mod_rewrite all but two files causing loop

  - by mpounsett

  I'm trying to set up a web site to allow the creation of a semaphore file to close the site. The logic I want to follow is: when the semaphore file exists and the request is not for /style.css or /favicon.icon show the content of /closed.html I have 1 and 3 working, but my exceptions for 2 result in a processing loop when style.css or favicon.ico are requested. This is my most recent attempt: RewriteEngine on RewriteCond %{REQUEST_URI} !^/style.css RewriteCond %{REQUEST_URI} !^/favicon.ico RewriteCond /usr/local/etc/site/closed -f RewriteRule ^.*$ /closed.html [L] This is in a VirtualHost block, not in a Directory. There is no .htaccess file in play. I have also recently tried this, based on an answer I found elsewhere, but with the same (looping) result: RewriteCond %{REQUEST_URI} ^/style.css [OR] RewriteCond %{REQUEST_URI} ^/favicon.ico RewriteRule ^.*$ - [L] RewriteCond /usr/local/etc/site/closed -f RewriteRule ^.*$ /closed.html [L] I expect a request for /style.css or /favicon.ico to fail to match one of the first two rewrite conditions, which should prevent the URI from being rewritten, which should stop the mod_rewrite iteration. However, mod_rewrite seems to think the URI has been rewritten in those cases, and iterates over the rules again (and again, and again). The above works properly in all cases except for style.css or favicon.ico. In those cases I exceed the loop limits. What am I missing here to cause the rewrite iteration to stop when someone requests style.css or favicon.ico? EDIT: Here's a loglevel 9 example of what happens using the first ruleset when a request arrives for /style.css. This is just the first two iterations.. it continues to loop identically until the limit is reached. 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1db0a0/initial] (2) init rewrite engine with requested uri /style.css 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1db0a0/initial] (3) applying pattern '^.*$' to uri '/style.css' 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1db0a0/initial] (4) RewriteCond: input='/style.css' pattern='!^/style.css' => not-matched 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1db0a0/initial] (1) pass through /style.css 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1dd0a0/initial] (2) init rewrite engine with requested uri /style.css 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1dd0a0/initial] (3) applying pattern '^.*$' to uri '/style.css' 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1dd0a0/initial] (4) RewriteCond: input='/style.css' pattern='!^/style.css' => not-matched 2001:4900:1044:0:145f:826e:6436:dc1 - - [29/May/2014:15:29:26 +0000] [host.example/sid#80c1c48b0][rid#80c1dd0a0/initial] (1) pass through /style.css

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• BizTalk host throttling &ndash; Singleton pattern and High database size

  - by S.E.R.

  Originally posted on: http://geekswithblogs.net/SERivas/archive/2013/06/30/biztalk-host-throttling-ndash-singleton-pattern-and-high-database-size.aspxI have worked for some days around the singleton pattern (for those unfamiliar with it, read this post by Victor Fehlberg) and have come across a few very interesting posts, among which one dealt with performance issues (here, also by Victor Fehlberg). Simply put: if you have an orchestration which implements the singleton pattern, then performances will continuously decrease as the orchestration receives and consumes messages, and that behavior is more obvious when the orchestration never ends (ie : it keeps looping and never terminates or completes). As I experienced the same kind of problem (actually I was alerted by SCOM, which told me that the host was being throttled because of High database size), I thought it would be a good idea to dig a little bit a see what happens deep inside BizTalk and thus understand the reasons for this behavior. NOTE: in this article, I will focus on this High database size throttling condition. I will try and work on the other conditions in some not too distant future… Test conditions The singleton orchestration For the purpose of this study, I have created the following orchestration, which is a very basic implementation of a singleton that piles up incoming messages, then does something else when a certain timeout has been reached without receiving another message: Throttling settings I have two distinct hosts : one that hosts the receive port (basic FILE port) : Ports_ReceiveHostone that hosts the orchestration : ProcessingHost In order to emphasize the throttling mechanism, I have modified the throttling settings for each of these hosts are as follows (all other parameters are set to the default value): [Throttling thresholds] Message count in database: 500 (default value : 50000) Evolution of performance counters when submitting messages Since we are investigating the High database size throttling condition, here are the performance counter that we should take a look at (all of them are in the BizTalk:Message Agent performance object): Database sizeHigh database sizeMessage delivery throttling stateMessage publishing throttling stateMessage delivery delay (ms)Message publishing delay (ms)Message delivery throttling state durationMessage publishing throttling state duration (If you are not used to Perfmon, I strongly recommend that you start using it right now: it is a wonderful tool that allows you to open the hood and see what is going on inside BizTalk – and other systems) Database size It is quite obvious that we will start by watching the database size and high database size counters, just to see when the first reaches the configured threshold (500) and when the second rings the alarm. NOTE : During this test I submitted 600 messages, one message at a time every 10ms to see the evolution of the counters we have previously selected. It might not show very well on this screenshot, but here is what happened: From 15:46:50 to 15:47:50, the database size for the Ports_ReceiveHost host (blue line) kept growing until it reached a maximum of 504.At 15:47:50, the high database size alert fires At first I was surprised by this result: why is it the database size of the receiving host that keeps growing since it is the processing host that piles up messages? Actually, it makes total sense. This counter measures the size of the database queue that is being filled by the host, not consumed. Therefore, the high database size alert is raised on the host that fills the queue: Ports_ReceiveHost. More information is available on the Public MPWiki page. Now, looking at the Message publishing throttling state for the receiving host (green line), we can see that a throttling condition has been reached at 15:47:50: We can also see that the Message publishing delay(ms) (blue line) has begun growing slowly from this point. All of this explains why performances keep decreasing when a singleton keeps processing new messages: the database size grows and when it has exceeded the Message count in database threshold, the host is throttled and the publishing delay keeps increasing. Digging further So, what happens to the database queue then? Is it flushed some day or does it keep growing and growing indefinitely? The real question being: will the host be throttled forever because of this singleton? To answer this question, I set the Message count in database threshold to 20 (this value is very low in order not to wait for too long, otherwise I certainly would have fallen asleep in front of my screen) and I submitted 30 messages. The test was started at 18:26. At 18:56 (ie : exactly 30min later) the throttling was stopped and the database size was divided by 2. 30 min later again, the database size had dropped to almost zero: I guess I’ll have to find some documentation and do some more testing before I sort this out! My guess is that some maintenance job is at work here, though I cannot tell which one Digging even further If we take a look at the Message delivery throttling state counter for the processing host, we can see that this host was also throttled during the submission of the 600 documents: The value for the counter was 1, meaning that Message delivery incoming rate for the host instance exceeds the Message delivery outgoing rate * the specified Rate overdrive factor (percent) value. We will see this another day… :) A last word Let’s end this article with a warning: DO NOT CHANGE THE THROTTLING SETTINGS LIGHTLY! The temptation can be great to just bypass throttling by setting very high values for each parameter (or zero in some cases, which simply disables throttling). Nevertheless, always keep in mind that this mechanism is here for a very good reason: prevent your BizTalk infrastructure from exploding!! So whatever you do with those settings, do a lot of testing and benchmarking!

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• Enable DreamScene in Any Version of Vista or Windows 7

  - by DigitalGeekery

  Windows DreamScene was a utility available for Vista Ultimate that allowed users to set video as desktop wallpaper. It was dropped in Windows 7, but we’ll take a look at how to play DreamScenes in all versions of Windows 7 or Vista. Downloading DreamScenes First, you’ll need to find some DreamScenes to download. We’ve found some nice ones at both DreamScene.org and DeviantArt. You can find those download links at the end of the article. They’ll come as compressed files, so you’ll need to extract them after downloading. Windows 7 DreamScene Activator If you are running Windows 7 you can use Windows 7 DreamScene Activator. This free portable utility enables DreamScene in both 32 & 64 bit versions of Windows 7. Users can then set either MPG or WMV files as desktop wallpaper. Download and extract the Windows 7 DreamScene Activator (link below). Once extracted, you’ll need to run the application as administrator. Right-click on the .exe and select Run as administrator. Click on Enable DreamScene. This will also restart Windows Explorer if it is open. To play your DreamScene, browse for the file in Windows Explorer, right-click the file and select Set as Desktop Background. Enjoy your new Windows 7 DreamScene.   Although it says it is for Windows 7 only, we were able to get it to work with no problems on Vista Home Premium x32 as well.   You can Pause the DreamScene at anytime by right-clicking on the desktop and selecting Pause DreamScene.   When you are ready for a change, click Disable DreamScene and switch back to your previous wallpaper. Using VLC Media Player Users of all versions of Windows 7 & Vista can enable a DreamScene using VLC. Recently, we showed you how to set a video as your desktop wallpaper in VLC.  Since DreamScenes are in MPEG or WMV format, we will use the same tactic to display them as desktop wallpaper. We’ll just need to make a few additional tweaks to the VLC settings. You’ll need to download and install VLC media player if you don’t already have it. You can find the download link below. Next, select Tools > Preferences from the Menu. Select the Video button on the left and then choose DirectX video output from the Output dropdown list. Next, select All under Show Settings at the lower left, then select the Video button on the left pane. Uncheck Show media title on video. This will prevent VLC from constantly showing the title of the video on the screen each time the video loops. Click Save and the restart VLC.   Now we will add the video to our playlist and set it to continuously loop. Select View > Playlist from the Menu. Select the Add file button from the bottom of the Playlist window and select Add file.   Browse for your file and click Open.   Click the Loop button at the bottom so the video plays in a continuous loop.   Now, we’re ready to play the video. After the video starts playing, select Video > DirectX Wallpaper from the Menu, then minimize VLC.   If you’re using Aero Themes, you may get a pop-up warning and Windows will switch automatically to a basic theme.   If looping one video gets to be a little repetitive, you can add multiple videos to your playlist in VLC and loop the entire playlist. Just make sure you toggle the Loop button on the playlist window to Loop All. Now you’ve got a nice DreamScene playing on your desktop. Another cool trick you can do with VLC is take snapshots of favorite movie scenes and set them as backgrounds. When you’re ready to go back to your old wallpaper, maximize VLC, select Video and click DirectX Wallpaper again to turn it off the video background. Occasionally we were left with a black screen and had to manually change our wallpaper back to normal even after turning off the DirectX Wallpaper. Note: Keep in mind that using the VLC method takes up a lot of resources so if you try to run it on older hardware, or say a netbook, you’re not going to get good results. We also tried to use the VLC method in XP, but couldn’t get it to work. If you have leave a comment and let us know. While the DreamScene feature never really caught on in Vista, we find them to be a cool way to pump a little life into your desktop on any version of Vista or Windows 7. Downloads DreamScenes from Dreamscene.org DreamScenes from DeviantArt Download VLC media player Windows 7 DreamScene Activator Similar Articles Productive Geek Tips Wait, How do I Turn on DreamScene Again?Enable Run Command on Windows 7 or Vista Start MenuEnable or Disable UAC From the Windows 7 / Vista Command LineUnderstanding Windows Vista Aero Glass RequirementsEnable Mapping to \HostnameC$ Share on Windows 7 or Vista TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Microsoft Office Web Apps Guide Know if Someone Accessed Your Facebook Account Shop for Music with Windows Media Player 12 Access Free Documentaries at BBC Documentaries Rent Cameras In Bulk At CameraRenter Download Songs From MySpace

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• Why enumerator structs are a really bad idea

  - by Simon Cooper

  If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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• XNA: Huge Tile Map, long load times

  - by Zach

  Recently I built a tile map generator for a game project. What I am very proud of is that I finally got it to the point where I can have a GIANT 2D map build perfectly on my PC. About 120000pixels by 40000 pixels. I can go larger actually, but I have only 1 draw back. #1 ram, the map currently draws about 320MB of ram and I know the Xbox allows 512MB I think? #2 It takes 20 mins for the map to build then display on the Xbox, on my PC it take less then a few seconds. I need to bring that 20 minutes of generating from 20 mins to how ever little bit I can, and how can a lower the amount of RAM usage while still being able to generate my map. Right now everything is stored in Jagged Arrays, each piece generating in a size of 1280x720 (the mother piece). Up to the amount that I need, every block is exactly 40x40 pixels however the blocks get removed from a List or regenerated in a List depending how close the mother piece is to the player. Saving A LOT of CPU, so at all times its no more then looping through 5184 some blocks. Well at least I'm sure of this. But how can I lower my RAM usage without hurting the size of the map, and how can I lower these INSANE loading times? EDIT: Let me explain my self better. Also I'd like to let everyone know now that I'm inexperienced with many of these things. So here is an example of the arrays I'm using. Here is the overall in a shorter term: int[][] array = new int[30][]; array[0] = new int[] { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }; array[1] = new int[] { 1, 3, 3, 3, 3, 1, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }; that goes on for around 30 arrays downward. Now for every time it hits a 1, it goes and generates a tile map 1280x720 and it does that exactly the way it does it above. This is how I loop through those arrays: for (int i = 0; i < array.Length; i += 1) { for (int h = 0; h < array[i].Length; h += 1) { } { Now how the tiles are drawn and removed is something like this: public void Draw(SpriteBatch spriteBatch, Vector2 cam) { if (cam.X >= this.Position.X - 1280) { if (cam.X <= this.Position.X + 2560) { if (cam.Y >= this.Position.Y - 720) { if (cam.Y <= this.Position.Y + 1440) { if (visible) { if (once == 0) { once = 1; visible = false; regen(); } } for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles[i].Draw(spriteBatch, cam); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles[i].Draw(spriteBatch, cam); } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } } If you guys still need more information just ask in the comments.

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