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• Stopping cookies being set from a domain (aka "cookieless domain") to increase site performance

  - by Django Reinhardt

  I was reading in Google's documentation about improving site speed. One of their recommendations is serving static content (images, css, js, etc.) from a "cookieless domain": Static content, such as images, JS and CSS files, don't need to be accompanied by cookies, as there is no user interaction with these resources. You can decrease request latency by serving static resources from a domain that doesn't serve cookies. Google then says that the best way to do this is to buy a new domain and set it to point to your current one: To reserve a cookieless domain for serving static content, register a new domain name and configure your DNS database with a CNAME record that points the new domain to your existing domain A record. Configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain. In your web pages, reference the domain name in the URLs for the static resources. This is pretty straight forward stuff, except for the bit where it says to "configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain". From what I've read, there's no setting in IIS that allows you to say "serve static resources", so how do I prevent ASP.NET from setting cookies on this new domain? At present, even if I'm just requesting a .jpg from the new domain, it sets a cookie on my browser, even though our application's cookies are set to our old domain. For example, ASP.NET sets an ".ASPXANONYMOUS" cookie that (as far as I'm aware) we're not telling it to do. Apologies if this is a real newb question, I'm new at this! Thanks.

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• Android: Speeding up display of (html-formatted) text

  - by prepbgg

  My app uses a StringBuilder to assemble paragraphs of text which are then displayed in a TextView within a ScrollView. The displaytext.xml layout file is: <?xml version="1.0" encoding="utf-8"?> <LinearLayout android:id="@+id/LinearLayout01" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#FFFFFF" xmlns:android="http://schemas.android.com/apk/res/android"> <ScrollView android:id="@+id/ScrollView01" android:layout_width="fill_parent" android:layout_height="wrap_content" > <TextView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/display_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textColor="#000000" > </TextView> </ScrollView> </LinearLayout> and the code that displays the StringBuilder object sbText is setContentView(R.layout.displaytext); TextView tv = (TextView)findViewById(R.id.display_text); tv.setText(Html.fromHtml(sbText.toString())); This works OK, except that it gets very slow as the amount of text grows. For example, to display 50 paragraphs totalling about 50KB of text takes over 5 seconds just to execute those three lines of code. Can anyone suggest how I can speed this up, please?

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• What hash algorithms are paralellizable? Optimizing the hashing of large files utilizing on mult-co

  - by DanO

  I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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• Jquery cycle plugin and image tag from code behind

  - by Geetha

  Hi All, I am using cycle plugin to show images. I am binding the html code for image from code behind. Problem: Images are not getting displayed. If i hard coded the image tag it is working. Code: $(window).load(function() { $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", data: "{}", url: "Default.aspx/GetImage", dataType: "json", success: function(data) { alert(data.d); $("#sample").html(data.d); $('#sample').cycle({ fx: 'fade', continuous: true, speed: 7500, timeout: 55000, pause: 1, sync: 1 }); } }); }); Data.d will give: <img src="Images/Frontbanner/s0.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s111.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s112.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s113.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s114.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s115.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s116.jpg" width="664" height="428" border="0" />

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• increase number of photos from flickr using json

  - by Andrew Welch

  Hi this is my code: Is is possible to get more photos from flickr. What is the standard / default number? $(document).ready(function(){ $.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?id=48719970@N07&lang=en-us&format=json&jsoncallback=?", function(data){ $.each(data.items, function(i, item){ var newurl = 'url(' + item.media.m + ')'; $("<div class='images'/>").css('background', newurl).css('backgroundPosition','top center').css('backgroundRepeat','no-repeat').appendTo("#images").wrap("<a target=\"_blank\ href='" + item.link + "'></a>"); }) $("#title").html(data.title); $("#description").html(data.description); $("#link").html("<a href='" + data.link + "' target=\"_blank\">Visit the Viget Inspiration Pool!</a>"); //Notice that the object here is "data" because that information sits outside of "items" in the JSON feed $('.jcycleimagecarousel').cycle({ fx: 'fade', speed: 300, timeout: 3000, next: '#next', prev: '#prev', pause: 1, random: 1 }); }); });

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• listview and datalist not updating,inserting

  - by raging_boner

  Data entered in textboxes is not getting updated in database. In debug mode I see that text1 and text2 in ItemUpdating event contain the same values as they had before calling ItemUpdating. Here's my listview control: <asp:ListView ID="ListView1" runat="server" onitemediting="ListView1_ItemEditing" onitemupdating="ListView1_ItemUpdating" oniteminserting="ListView1_ItemInserting"> //LayoutTemplate removed <ItemTemplate> <asp:Label ID="Label2" runat="server" Text='<%#Eval("id")%>'></asp:Label> <asp:Label ID="Label3" runat="server" Text='<%#Eval("text1")%>'></asp:Label> <asp:LinkButton ID="LinkButton2" CommandName="Edit" runat="server">Edit</asp:LinkButton> <asp:LinkButton ID="LinkButton4" CommandName="Delete" runat="server">Delete</asp:LinkButton> </ItemTemplate> <EditItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%#Eval("id")%>'></asp:Label> <asp:TextBox ID="TextBox1" runat="server" Text='<%#Eval("text1")%>' TextMode="MultiLine" /> <asp:TextBox ID="TextBox2" runat="server" Text='<%#Eval("text2")%>' Height="100" TextMode="MultiLine" /> <asp:LinkButton ID="LinkButton1" CommandName="Update" CommandArgument='<%# Eval("id")%>' runat="server">Update</asp:LinkButton> <asp:LinkButton ID="LinkButton5" CommandName="Cancel" runat="server">Cancel</asp:LinkButton> </EditItemTemplate> <InsertItemTemplate> <asp:TextBox ID="TextBox3" runat="server" TextMode="MultiLine" Height="100"></asp:TextBox> <asp:TextBox ID="TextBox4" runat="server" Height="100" TextMode="MultiLine"></asp:TextBox> <asp:LinkButton ID="LinkButton3" runat="server">Insert</asp:LinkButton> </InsertItemTemplate> </asp:ListView> Codebehind file: protected void ListView1_ItemEditing(object sender, ListViewEditEventArgs e) { ListView1.EditIndex = e.NewEditIndex; BindList(); } protected void ListView1_ItemUpdating(object sender, ListViewUpdateEventArgs e) { ListViewItem myItem = ListView1.Items[ListView1.EditIndex]; Label id = (Label)myItem.FindControl("Label1"); int dbid = int.Parse(id.Text); TextBox text1 = (TextBox)myItem.FindControl("Textbox1"); TextBox text2 = (TextBox)myItem.FindControl("Textbox2"); //tried to work withNewValues below, but they don't work, "null reference" error is being thrown //text1.Text = e.NewValues["text1"].ToString(); //text2.Text = e.NewValues["text2"].ToString(); //odbc connection routine removed. //i know that there should be odbc parameteres: comm = new OdbcCommand("UPDATE table SET text1 = '" + text1.Text + "', text2 = '" + text2.Text + "' WHERE id = '" + dbid + "'", connection); comm.ExecuteNonQuery(); conn.Close(); ListView1.EditIndex = -1; //here I databind ListView1 } What's wrong with updating of text1.Text, text2.Text in ItemUpdating event? Should I use e.NewValues property? If so, how to use it? Thanks in advance for any help.

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• How can I accelerate the generation of the an MD5 Checksum within vb.net?

  - by Richard

  I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. It's an issue since we will eventually be dealing with thousands of these files. I would like to find a faster way to generate the checksum other than using the System.Security.Cryptography.MD5CryptoServiceProvider I don't care if this means using a specialized hardware card, provided it works and is not to ungodly expensive. I would prefer to have a method of encoding that provided some feedback as to how far the process has gone along so I can display it like I do now. The application is written in vb.net. I would prefer to be able to use it as component, library, reference within my application, but I'm willing to call an outside application if there is enough improvement in the speed of generating the checksum. Needless to say, the checksum must be consistent and correct. :-) Thank you in advance for your time and efforts, Richard

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• Most efficient way to LIMIT results in a JOIN?

  - by johnnietheblack

  I have a fairly simple one-to-many type join in a MySQL query. In this case, I'd like to LIMIT my results by the left table. For example, let's say I have an accounts table and a comments table, and I'd like to pull 100 rows from accounts and all the associated comments rows for each. Thy only way I can think to do this is with a sub-select in in the FROM clause instead of simply selecting FROM accounts. Here is my current idea: SELECT a.*, c.* FROM (SELECT * FROM accounts LIMIT 100) a LEFT JOIN `comments` c on c.account_id = a.id ORDER BY a.id However, whenever I need to do a sub-select of some sort, my intermediate level SQL knowledge feels like it's doing something wrong. Is there a more efficient, or faster, way to do this, or is this pretty good? By the way... This might be the absolute simplest way to do this, which I'm okay with as an answer. I'm simply trying to figure out if there IS another way to do this that could potentially compete with the above statement in terms of speed.

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• What is the fastest way to filter a list of strings when making an Intellisense/Autocomplete list?

  - by user559548

  Hello everyone, I'm writing an Intellisense/Autocomplete like the one you find in Visual Studio. It's all fine up until when the list contains probably 2000+ items. I'm using a simple LINQ statement for doing the filtering: var filterCollection = from s in listCollection where s.FilterValue.IndexOf(currentWord, StringComparison.OrdinalIgnoreCase) >= 0 orderby s.FilterValue select s; I then assign this collection to a WPF Listbox's ItemSource, and that's the end of it, works fine. Noting that, the Listbox is also virtualised as well, so there will only be at most 7-8 visual elements in memory and in the visual tree. However the caveat right now is that, when the user types extremely fast in the richtextbox, and on every key up I execute the filtering + binding, there's this semi-race condition, or out of sync filtering, like the first key stroke's filtering could still be doing it's filtering or binding work, while the fourth key stroke is also doing the same. I know I could put in a delay before applying the filter, but I'm trying to achieve a seamless filtering much like the one in Visual Studio. I'm not sure where my problem exactly lies, so I'm also attributing it to IndexOf's string operation, or perhaps my list of string's could be optimised in some kind of index, that could speed up searching. Any suggestions of code samples are much welcomed. Thanks.

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• Groovy htmlunit getFirstByXPath returning null

  - by StartingGroovy

  I have had a few issues with HtmlUnit returning nulls lately and am looking for guidance. each of my results for grabbing the first row of a website have returned null. I am wondering if someone can A) explain why they might be returning null B) explain better ways (if there are some) to go about getting the information Here is my current code (URL is in the source): client = new WebClient(BrowserVersion.FIREFOX_3) client.javaScriptEnabled = false def url = "http://www.hidemyass.com/proxy-list/" page = client.getPage(url) IpAddress = page.getFirstByXPath("//html/body/div/div/form/table/tbody/tr/td[2]").getValue() println "IP Address is: $data" //returns null //Port_Number is an Image Country = page.getFirstByXPath("//html/body/div/div/form/table/tbody/tr/td[4][@class='country']/@rel").getValue() println "Country abbreviation is: $Country" //differentiate speed and connection by name of gif? Type = page.getFirstByXPath("//html/body/div/div/form/table/tbody/tr/td[7]").getValue() println "Proxy type is: $Type" Anonymity = page.getFirstByXPath("//html/body/div/div/form/table/tbody/tr/td[8]").getValue() println "Anonymity Level is: $Anonymity" client.closeAllWindows() Right now all of my XPaths return null and .getValue() obviously doesn't work on null. I also have questions as to what I should do about the PORT since it is an image? Is there a better alternative than downloading it and attempting to solve it by OCR? Side Note There is no significance in this site, I was just looking for a site that I could practice scraping on (the last one I ran into issues of fragment identities and couldn't get an answer to: HtmlUnit getByXpath returns null and HtmlUnit and Fragment Identities )

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• Splitting a set of object into several subsets of 'similar' objects

  - by doublep

  Suppose I have a set of objects, S. There is an algorithm f that, given a set S builds certain data structure D on it: f(S) = D. If S is large and/or contains vastly different objects, D becomes large, to the point of being unusable (i.e. not fitting in allotted memory). To overcome this, I split S into several non-intersecting subsets: S = S1 + S2 + ... + Sn and build Di for each subset. Using n structures is less efficient than using one, but at least this way I can fit into memory constraints. Since size of f(S) grows faster than S itself, combined size of Di is much less than size of D. However, it is still desirable to reduce n, i.e. the number of subsets; or reduce the combined size of Di. For this, I need to split S in such a way that each Si contains "similar" objects, because then f will produce a smaller output structure if input objects are "similar enough" to each other. The problems is that while "similarity" of objects in S and size of f(S) do correlate, there is no way to compute the latter other than just evaluating f(S), and f is not quite fast. Algorithm I have currently is to iteratively add each next object from S into one of Si, so that this results in the least possible (at this stage) increase in combined Di size: for x in S: i = such i that size(f(Si + {x})) - size(f(Si)) is min Si = Si + {x} This gives practically useful results, but certainly pretty far from optimum (i.e. the minimal possible combined size). Also, this is slow. To speed up somewhat, I compute size(f(Si + {x})) - size(f(Si)) only for those i where x is "similar enough" to objects already in Si. Is there any standard approach to such kinds of problems? I know of branch and bounds algorithm family, but it cannot be applied here because it would be prohibitively slow. My guess is that it is simply not possible to compute optimal distribution of S into Si in reasonable time. But is there some common iteratively improving algorithm?

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• I need to make a multithreading program (python)

  - by Andreawu98

  import multiprocessing import time from itertools import product out_file = open("test.txt", 'w') P = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p','q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',] N = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] M = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'] c = int(input("Insert the number of digits you want: ")) n = int(input("If you need number press 1: ")) m = int(input("If you need upper letters press 1: ")) i = [] if n == 1: P = P + N if m == 1: P = P + M then = time.time() def worker(): for i in product(P, repeat=c): #check every possibilities k = '' for z in range(0, c): # k = k + str(i[z]) # print each possibility in a txt without parentesis or comma out_file.write( k + '\n') # out_file.close() now = time.time() diff = str(now - then) # To see how long does it take print(diff) worker() time.sleep(10) # just to check console The code check every single possibility and print it out in a test.txt file. It works but I really can't understand how can I speed it up. I saw it use 1 core out of my quad core CPU so I thought Multi-threading might work even though I don't know how. Please help me. Sorry for my English, I am from Italy.

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• Deleting While Iterating in Ruby?

  - by Jesse J

  I'm iterating over a very large set of strings, which iterates over a smaller set of strings. Due to the size, this method takes a while to do, so to speed it up, I'm trying to delete one of the strings from the smaller set that no longer needs to be used. Below is my current code: Ms::Fasta.foreach(@database) do |entry| all.each do |set| if entry.header[1..40].include? set[1] + "|" startVal = entry.sequence.scan_i(set[0])[0] if startVal != nil @locations << [set[0], set[1], startVal, startVal + set[1].length] all.delete(set) end end end end The problem I face is that the easy way, array.delete(string), effectively adds a break statement to the inner loop, which messes up the results. The only way I know how to fix this is to do this: Ms::Fasta.foreach(@database) do |entry| i = 0 while i < all.length set = all[i] if entry.header[1..40].include? set[1] + "|" startVal = entry.sequence.scan_i(set[0])[0] if startVal != nil @locations << [set[0], set[1], startVal, startVal + set[1].length] all.delete_at(i) i -= 1 end end i += 1 end end This feels kind of sloppy to me. Is there a better way to do this? Thanks.

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• can a python script know that another instance of the same script is running... and then talk to it?

  - by Justin Grant

  I'd like to prevent multiple instances of the same long-running python command-line script from running at the same time, and I'd like the new instance to be able to send data to the original insance before the new instance commits suicide. How can I do this in a cross-platform way? Specifically, I'd like to enable the following behavior: "foo.py" is launched from the command line, and it will stay running for a long time-- days or weeks until the machine is rebooted or the parent process kills it. every few minutes the same script is launched again, but with different command-line parameters when launched, the script should see if any other instances are running. if other instances are running, then instance #2 should send its command-line parameters to instance #1, and then instance #2 should exit. instance #1, if it receives command-line parameters from another script, should spin up a new thread and (using the command-line parameters sent in the step above) start performing the work that instance #2 was going to perform. So I'm looking for two things: how can a python program know another instance of itself is running, and then how can one python command-line program communicate with another? Making this more complicated, the same script needs to run on both Windows and Linux, so ideally the solution would use only the Python standard library and not any OS-specific calls. Although if I need to have a Windows codepath and an *nix codepath (and a big if statement in my code to choose one or the other), that's OK if a "same code" solution isn't possible. I realize I could probably work out a file-based approach (e.g. instance #1 watches a directory for changes and each instance drops a file into that directory when it wants to do work) but I'm a little concerned about cleaning up those files after a non-graceful machine shutdown. I'd ideally be able to use an in-memory solution. But again I'm flexible, if a persistent-file-based approach is the only way to do it, I'm open to that option. More details: I'm trying to do this because our servers are using a monitoring tool which supports running python scripts to collect monitoring data (e.g. results of a database query or web service call) which the monitoring tool then indexes for later use. Some of these scripts are very expensive to start up but cheap to run after startup (e.g. making a DB connection vs. running a query). So we've chosen to keep them running in an infinite loop until the parent process kills them. This works great, but on larger servers 100 instances of the same script may be running, even if they're only gathering data every 20 minutes each. This wreaks havoc with RAM, DB connection limits, etc. We want to switch from 100 processes with 1 thread to one process with 100 threads, each executing the work that, previously, one script was doing. But changing how the scripts are invoked by the monitoring tool is not possible. We need to keep invocation the same (launch a process with different command-line parameters) but but change the scripts to recognize that another one is active, and have the "new" script send its work instructions (from the command line params) over to the "old" script.

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• Correct way to switch between UIView with ARC. My way leads to memory leaks :( (iOS)

  - by Andrei Golubev

  i use xcode 4.4 with ARC on.. I have dynamically created UIViews in the ViewController.m: UIView*myviews[10]; Then in the - (void)viewDidLoad function i fill each of it with pictures i need myviews[viewIndex] = [[UIView alloc]initWithFrame:myrec]; UIImage *testImg; UIImageView * testImgView; testImg = [UIImage imageNamed:[NSString stringWithFormat:@"imgarray%d.png", viewIndex]; testImgView.image = testImg; viewindex++; So all seems to be fine, when i want to jump from one view to another i do with two buttons next: [self.view addSubview:views[viewIndex]]; CATransition *animation = [CATransition animation]; [animation setDelegate:self]; [animation setDuration:1.0f]; [animation setType:@"rippleEffect"]; [animation setSubtype:kCATransitionFromTop]; //[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]]; [self.view.layer addAnimation:animation forKey:@"transitionViewAnimation"]; Nothing seems to be bad, but the memory consumption grows with huge speed when i switch between views.. and then i get low memory warning or sometimes application will just crash. I have tried to use UIViewController array and was switching between the controllers: nothing changes, the memory low warning is what i end up with.. Maybe i need to clean the memory somehow? But how? ARC does not allow to use release and so on.. last what i have tried (sorry, maybe not very professional) before to add new subview is this NSArray *viewsToRemove = [self.view subviews]; for (UIView *views in viewsToRemove) { [views removeFromSuperview]; } But this does not help either.. Please don't judge too strong, i am still new to iOS and Objective-c..

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• IIS7 dynamic content compression and webservices

  - by vandalo

  I am moving and old asmx webservice to a new server with IIS7. This webservice basically sends a big dataset (10mb+) to a winform application. The old solution was implemented using a custom soap extension which compressed the content before sending the stream to the client. The client, of course, implemented the same custom soap extension, to decompressed the stream in a dataset. Everything has worked pretty well for years. My customer doesn't want to change the code upgrading to WCF. They just want to put the old App on the new server and use the new dynamic content compression features. We're testing things on a test server (win serv 2008) and it seems that it's working pretty well, even if it seems slow: we can't see any difference in performance (speed) between the uncompressed and compressed stream. Here's the question. Where should I put the settings? Most people say I can't put it in my web.config; others say it can be put there. I am a bit confused. Are there any tricks or things I should know? What about mimeTypes? Should I set some parameters, somewhere? ... considering my stream is XML (dataset) ?? Thanks to everyone who would like to help Alberto

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• Efficiency of manually written loops vs operator overloads (C++)

  - by Sagekilla

  Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

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• fastest way to check to see if a certain index in a linq statement is null

  - by tehdoommarine

  Basic Details I have a linq statement that grabs some records from a database and puts them in a System.Linq.Enumerable: var someRecords = someRepoAttachedToDatabase.Where(p=>true); Suppose this grabs tons (25k+) of records, and i need to perform operations on all of them. to speed things up, I have to decided to use paging and perform the operations needed in blocks of 100 instead of all of the records at the same time. The Question The line in question is the line where I count the number of records in the subset to see if we are on the last page; if the number of records in subset is less than the size of paging - then that means there are no more records left. What I would like to know is what is the fastest way to do this? Code in Question int pageSize = 100; bool moreData = true; int currentPage = 1; while (moreData) { var subsetOfRecords = someRecords.Skip((currentPage - 1) * pageSize).Take(pageSize); //this is also a System.Linq.Enumerable if (subsetOfRecords.Count() < pageSize){ moreData = false;} //line in question //do stuff to records in subset currentPage++; } Things I Have Considered subsetOfRecords.Count() < pageSize subsetOfRecords.ElementAt(pageSize - 1) == null (causes out of bounds exception - can catch exception and set moreData to false there) Converting subsetOfRecords to an array (converting someRecords to an array will not work due to the way subsetOfRecords is declared - but I am open to changing it) I'm sure there are plenty of other ideas that I have missed.

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• Creating many polygons with OpenGL is slow?

  - by user146780

  I want to draw many polygons to the screen but i'm quickly noticing that it slows down quickly. As a test I did this: for(int i = 0; i < 50; ++i) { glBegin( GL_POLYGON); glColor3f( 0.0f, 1, 0.0f ); glVertex2f( 500.0 + frameGL.GetCameraX(), 0.0f + frameGL.GetCameraY()); glColor3f( 0.0f, 1.0f, 0.0f ); glVertex2f( 900.0 + frameGL.GetCameraX(), 0.0f + frameGL.GetCameraY()); glColor3f( 0.0f, 0.0f, 0.5 ); glVertex2f(900.0 + frameGL.GetCameraX(), 500.0f + frameGL.GetCameraY() + (150)); glColor3f( 0.0f, 1.0f, 0.0f ); glVertex2f( 500 + frameGL.GetCameraX(), 500.0f + frameGL.GetCameraY()); glColor3f( 1.0f, 1.0f, 0.0f ); glVertex2f( 300 + frameGL.GetCameraX(), 200.0f + frameGL.GetCameraY()); glEnd(); } This is only 50 polygons and already it's gtting slow. I can't upload them directly to the card because my program will allow the user to reshape the verticies. My question is, how can I speed this up. I'm not using depth. I also know it's not my GetCamera() functions because if I create 500,000 polygons spread apart t's fine, it just has trouble showing them in the view. If a graphics card can support 500,000,000 on screen polygons per second, this should be easy right? Thanks

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• nginx bad gateway 502 with mono fastcgi

  - by Bradley Lederholz Leatherwood

  Hello so I have been trying to get my website to run on mono (on ubuntu server) and I have followed these tutorials almost to the letter: However when my directory is not blank fastcgi logs reveal this: Notice Beginning to receive records on connection. Error Failed to process connection. Reason: Exception has been thrown by the target of an invocation. I am not really sure what this means, and depending on what I do I can get another error that tells me the resource cannot be found: The resource cannot be found. Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly. Requested URL: /Default.aspx/ Version information: Mono Runtime Version: 2.10.8 (tarball Thu Aug 16 23:46:03 UTC 2012) ASP.NET Version: 4.0.30319.1 If I should provide some more information please let me know. Edit: I am now getting a nginx gateway error. My nginx configuration file looks like this: server { listen 2194; server_name localhost; access_log $HOME/WWW/nginx.log; location / { root $HOME/WWW/dev/; index index.html index.html default.aspx Default.aspx Index.cshtml; fastcgi_index Views/Home/; fastcgi_pass 127.0.0.1:8000; include /etc/nginx/fastcgi_params; } } Running the entire thing with xsp4 I have discovered what the "Exception has been thrown by the target of an invocation." Handling exception type TargetInvocationException Message is Exception has been thrown by the target of an invocation. IsTerminating is set to True System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. Server stack trace: at System.Reflection.MonoCMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in :0 at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in :0 at System.Runtime.Serialization.ObjectRecord.LoadData (System.Runtime.Serialization.ObjectManager manager, ISurrogateSelector selector, StreamingContext context) [0x00000] in :0 at System.Runtime.Serialization.ObjectManager.DoFixups () [0x00000] in :0 at System.Runtime.Serialization.Formatters.Binary.ObjectReader.ReadNextObject (System.IO.BinaryReader reader) [0x00000] in :0 at System.Runtime.Serialization.Formatters.Binary.ObjectReader.ReadObjectGraph (BinaryElement elem, System.IO.BinaryReader reader, Boolean readHeaders, System.Object& result, System.Runtime.Remoting.Messaging.Header[]& headers) [0x00000] in :0 at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.NoCheckDeserialize (System.IO.Stream serializationStream, System.Runtime.Remoting.Messaging.HeaderHandler handler) [0x00000] in :0 at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize (System.IO.Stream serializationStream) [0x00000] in :0 at System.Runtime.Remoting.RemotingServices.DeserializeCallData (System.Byte[] array) [0x00000] in :0 at (wrapper xdomain-dispatch) System.AppDomain:DoCallBack (object,byte[]&,byte[]&) Exception rethrown at [0]: --- System.ArgumentException: Couldn't bind to method 'SetHostingEnvironment'. at System.Delegate.GetCandidateMethod (System.Type type, System.Type target, System.String method, BindingFlags bflags, Boolean ignoreCase, Boolean throwOnBindFailure) [0x00000] in :0 at System.Delegate.CreateDelegate (System.Type type, System.Type target, System.String method, Boolean ignoreCase, Boolean throwOnBindFailure) [0x00000] in :0 at System.Delegate.CreateDelegate (System.Type type, System.Type target, System.String method) [0x00000] in :0 at System.DelegateSerializationHolder+DelegateEntry.DeserializeDelegate (System.Runtime.Serialization.SerializationInfo info) [0x00000] in :0 at System.DelegateSerializationHolder..ctor (System.Runtime.Serialization.SerializationInfo info, StreamingContext ctx) [0x00000] in :0 at (wrapper managed-to-native) System.Reflection.MonoCMethod:InternalInvoke (System.Reflection.MonoCMethod,object,object[],System.Exception&) at System.Reflection.MonoCMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in :0 --- End of inner exception stack trace --- at (wrapper xdomain-invoke) System.AppDomain:DoCallBack (System.CrossAppDomainDelegate) at (wrapper remoting-invoke-with-check) System.AppDomain:DoCallBack (System.CrossAppDomainDelegate) at System.Web.Hosting.ApplicationHost.CreateApplicationHost (System.Type hostType, System.String virtualDir, System.String physicalDir) [0x00000] in :0 at Mono.WebServer.VPathToHost.CreateHost (Mono.WebServer.ApplicationServer server, Mono.WebServer.WebSource webSource) [0x00000] in :0 at Mono.WebServer.XSP.Server.RealMain (System.String[] args, Boolean root, IApplicationHost ext_apphost, Boolean quiet) [0x00000] in :0 at Mono.WebServer.XSP.Server.Main (System.String[] args) [0x00000] in :0

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• How can I solve the Log Pile wooden puzzle with a computer program?

  - by craig1410

  Can anyone suggest how to solve the Log Pile wooden puzzle using a computer program? See here to visualise the puzzle: http://www.puzzlethis.co.uk/products/madcow/the_log_pile.htm The picture only shows some of the pieces. The full set of 10 pieces are configured as follows with 1 representing a peg, -1 representing a hole and 0 representing neither a peg nor a hole. -1,1,0,-1,0 1,0,1,0,0 1,-1,1,0,0 -1,-1,0,0,-1 -1,1,0,1,0 0,1,0,0,1 1,0,-1,0,-1 0,-1,0,1,0 0,0,-1,1,-1 1,0,-1,0,0 The pieces can be interlocked in two layers of 5 pieces each with the top layer at 90 degrees to the bottom layer as shown in the above link. I have already created a solution to this problem myself using Java but I feel that it was a clumsy solution and I am interested to see some more sophisticated solutions. Feel free to either suggest a general approach or to provide a working program in the language of your choice. My approach was to use the numeric notation above to create an array of "Logs". I then used a combination/permutation generator to try all possible arrangements of the Logs until a solution was found where all the intersections equated to zero (ie. Peg to Hole, Hole to Peg or Blank to Blank). I used some speed-ups to detect the first failed intersection for a given permutation and move on to the next permutation. I hope you find this as interesting as I have. Thanks, Craig.

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• Is there any performance issue using Row_Number to implement table paging in Sql Server 2008?

  - by majkinetor

  I want to implement table paging using this method: SET @PageNum = 2; SET @PageSize = 10; WITH OrdersRN AS ( SELECT ROW_NUMBER() OVER(ORDER BY OrderDate, OrderID) AS RowNum ,* FROM dbo.Orders ) SELECT * FROM OrdersRN WHERE RowNum BETWEEN (@PageNum - 1) * @PageSize + 1 AND @PageNum * @PageSize ORDER BY OrderDate ,OrderID; Is there anything I should be aware of ? Table has millions of records. Thx. EDIT: After using suggested MAXROWS method for some time (which works really really fast) I had to switch back to ROW_NUMBER method because of its greater flexibility. I am also very happy about its speed so far (I am working with View having more then 1M records with 10 columns). To use any kind of query I use following modification: PROCEDURE [dbo].[PageSelect] ( @Sql nvarchar(512), @OrderBy nvarchar(128) = 'Id', @PageNum int = 1, @PageSize int = 0 ) AS BEGIN SET NOCOUNT ON Declare @tsql as nvarchar(1024) Declare @i int, @j int if (@PageSize <= 0) OR (@PageSize > 10000) SET @PageSize = 10000 -- never return more then 10K records SET @i = (@PageNum - 1) * @PageSize + 1 SET @j = @PageNum * @PageSize SET @tsql = 'WITH MyTableOrViewRN AS ( SELECT ROW_NUMBER() OVER(ORDER BY ' + @OrderBy + ') AS RowNum ,* FROM MyTableOrView WHERE ' + @Sql + ' ) SELECT * FROM MyTableOrViewRN WHERE RowNum BETWEEN ' + CAST(@i as varchar) + ' AND ' + cast(@j as varchar) exec(@tsql) END If you use this procedure make sure u prevented sql injection.

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• Difference between MVC FilterAttribute and Filter

  - by zaaaaphod

  I'm trying to write my own custom AuthorizationAttribute that uses DI. I'm using the MUNQ IoC provider for it's speed and have decided to use constructor injection on all my classes as opposed to post instatiation property binding (because I prefer it). I'm trying to write a custom IFilterProvider that will use my IoC container to return requests for filters (so that I can map concrete classes using the container). I've come up with the following. public class FilterProvider : IFilterProvider { private readonly IocContainer _container; public FilterProvider(IocContainer container) { _container = container; } public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor) { var x = Enumerable.Union<Object>(_container.ResolveAll<IActionFilter>(), _container.ResolveAll<IAuthorizationFilter>()); foreach (Filter actionFilter in x) yield return new Filter(actionFilter, FilterScope.First, null); } } The above code will fail during the foreach because my objects that implement IAuthorizationFilter are based on FilterAttribute and not Filter My question is, what is the difference between Filter and FilterAttribute? I would have thought that there would have been a common link between them, unless I'm missing something. Another deeper question is, how come there is no IFilterAttributeProvider that would support IEnumerable GetFilters(...) Is there some other way that I should be using to resolve IAuthorizationFilter via my IoC container? Thank you very much for your help. Z

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• Animation management in COCOS2D iphone.

  - by shreya

  Hi All, I have near about 255 image frames for background animation, 99 frames of enemy sprite and 125 frames of player sprite. All animations are running simultaneously on the screen. That is background animation is running and 4-5 enemies are on the screen are present at a time, also player is there at the same time. Take a look at the code below, CCAnimation *_enemyAnimation = [CCAnimation animationWithName:@"Enemy" delay:0.1f]; for (int i = 1; i<99; i++) { [_enemyAnimation addFrameWithFilename:[NSString stringWithFormat:@"enemy %02d.jpg",i]]; } id action1 = [CCAnimate actionWithAnimation: _enemyAnimation]; [_enemySprite runAction:[CCRepeatForever actionWithAction: action1]]; [self schedule:@selector(BackToGameLogic:) interval:5.0]; This makes my game too slower and consumes memory about 65MB in the allocations. How should I manage my animations so there will be improvement in speed and memory consumption will be reduced?. Please suggest me the way. Thanks.

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• Quickest way to compare a bunch of array or list of values.

  - by zapping

  Can you please let me know on the quickest and efficient way to compare a large set of values. Its like there are a list of parent codes(string) and each code has a series of child values(string). The child lists have to be compared with each other and find out duplicates and count how many times they repeat. code1(code1_value1, code1_value2, code3_value3, ..., code1_valueN); code2(code2_value1, code1_value2, code2_value3, ..., code2_valueN); code3(code2_value1, code3_value2, code3_value3, ..., code3_valueN); . . . codeN(codeN_value1, codeN_value2, codeN_value3, ..., codeN_valueN); The lists are huge say like there are 100 parent codes and each has about 250 values in them. There will not be duplicates within a code list. Doing it in java and the solution i could figure out is. Store the values of first set of code in as codeMap.put(codeValue, duplicateCount). The count initialized to 0. Then compare the rest of the values with this. If its in the map then increment the count otherwise append it to the map. The downfall of this is to get the duplicates. Another iteration needs to be performed on a very large list. An alternative is to maintain another hashmap for duplicates like duplicateCodeMap.put(codeValue, duplicateCount) and change the initial hashmap to codeMap.put(codeValue, codeValue). Speed is what is requirement. Hope one of you can help me with it.

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