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• Spring 2.0.0/2.0.6 to 3.0.5 migration stories

  - by Pangea

  We are in the process of migrating to 3.0.5 of spring from 2.0.x. We mainly use spring in below scenarios custom scope: thread local scope persistence: jdbc+hibernate 3.6 (but moving to mix of ejb 3.0+jpa 2.0+hibernate, not sure if all 3 can co-exist in 1 app) transactions: local (but planning to use jta due to the necessity of using multiple persistence inits, and has to use ejb+jpa+hibernate in 1 single trans), declarative trans mgmt parent-child contexts cxf annotations+xml OracleLobHandler Resource/ResourceBundleMessageResource JSF/Facelets with FacesSpringVariableResolver ActiveMQ integration Quartz integration TaskExecutor JMX exporter HttpExporter/Invoker Appreciate if someone can share their experiences like what to watch out for head aches/pain points which ones to drop for better alternate choices in new 3.0.5 release Is it better to switch from commons/iscreen validator to Hibernate Validator (Spec impl) or Spring Validator Is there a bean mapping framework in spring that i can use instead of Dozer XSLT transformation helper: currently we have small homegrown framework to cache xslts during load. if spring can do that for me then I would like to drop this Encryption/Decryption support. Password generation support. Authentication with SALT any SAML (or claims based secur New ideas Suggestions Switch to latest version of aspectj Upgrade guide from 2.5 to 3.0.5

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• Stack usage with MMX intrinsics and Microsoft C++

  - by arik-funke

  I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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• How to detect changing directory size in Perl

  - by materiamage

  Hello, I am trying to find a way of monitoring directories in Perl, in particular the size of a directory, and upon detecting a change in directory size, perform a particular action. The issue I have is with large files that require a noticeable amount of time to copy into this directory, i.e. 100MB. What happens (in Windows, not Unix) is the system reserves enough disk space for the entire file, even though the file is still copying in progress. This causes problems for me, because my script will try to perform an action on this file that has not finished copying over. I can easily detect directory size changes in Unix via 'du', but 'du' in Windows does not behave the same way. Are there any accurate methods of detecting directory size changes in Perl? Edit: Some points to clarify: - My Perl script is only monitoring a particular directory, and upon detecting a new file or a new directory, perform an action on this new file or directory. It is not copying any files; users on the network will be copying files into the directory I am monitoring. - The problem occurs when a new file or directory appears (copied, not moved) that is significantly large ( 100MB, but usually a couple GB) and my program fires before this copy completes - In Unix I can easily 'du' to see that the file/directory in question is growing in size, and take the appropriate action - In Windows the size is static, so I cannot detect this change - opendir/readdir/closedir is not feasible, as some of the directories that appear may contain thousands of files, and I want to avoid the overhead of Ideally I would like my program to be triggered on change, but I am not sure how to do this. As of right now it busy waits until it detects a change. The change in file/directory size is not in my control.

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• Minimal "Task Queue" with stock Linux tools to leverage Multicore CPU

  - by Manuel

  What is the best/easiest way to build a minimal task queue system for Linux using bash and common tools? I have a file with 9'000 lines, each line has a bash command line, the commands are completely independent. command 1 > Logs/1.log command 2 > Logs/2.log command 3 > Logs/3.log ... My box has more than one core and I want to execute X tasks at the same time. I searched the web for a good way to do this. Apparently, a lot of people have this problem but nobody has a good solution so far. It would be nice if the solution had the following features: can interpret more than one command (e.g. command; command) can interpret stream redirects on the lines (e.g. ls > /tmp/ls.txt) only uses common Linux tools Bonus points if it works on other Unix-clones without too exotic requirements.

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• Managing inverse relationships without CoreData

  - by Nathaniel Martin

  This is a question for Objective-J/Cappuccino, but I added the cocoa tag since the frameworks are so similar. One of the downsides of Cappuccino is that CoreData hasn't been ported over yet, so you have to make all your model objects manually. In CoreData, your inverse relationships get managed automatically for you... if you add an object to a to-many relationship in another object, you can traverse the graph in both directions. Without CoreData, is there any clean way to setup those inverse relationships automatically? For a more concrete example, let's take the typical Department and Employees example. To use rails terminology, a Department object has-many Employees, and an Employee belongs-to a Department. So our Department model has an NSMutableSet (or CPMutableSet ) "employees" that contains a set of Employees, and our Employee model has a variable "department" that points back to the Department model that owns it. Is there an easy way to make it so that, when I add a new Employee model into the set, the inverse relationship (employee.department) automatically gets set? Or the reverse: If I set the department model of an employee, then it automatically gets added to that department's employee set? Right know I'm making an object, "ValidatedModel" that all my models subclass, which adds a few methods that setup the inverse relationships, using KVO. But I'm afraid that I'm doing a lot of pointless work, and that there's already an easier way to do this. Can someone put my concerns to rest?

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• Uncrackable anti-piracy protection/DRM even possible? [closed]

  - by some guy

  I hope that this is programming-related enough. You have probably heard about Ubisofts recent steps against piracy. (New DRM requires a constant connection to the Ubisoft server) Many people including me see this as intolerable because the only ones suffering from it at the end are the paying customers. Now to the actual question(s): Ubisoft justified this by calling this mechanism "Uncrackable, only playable by the paying customers". Is a so called uncrackable DRM even possible? You can reverse-engineer and modify everything, even if it takes long. Isn't Ubisoft already lying by calling something not crackable? I mean, hey - With the game you get all its content (textures, models, you know) and some anti-piracy mechanism hardcoded into it. How could that be "uncrackable"? You can just patch the unwanted mechanisms out ---- "Pirates" play the cracked game without problems and the paying customers are the idiots by having constant problems with the game and being unable to play it without a (working) internet connection. What are the points Ubisoft sees in this? If they are at least a bit intelligent and informed they know their anti-piracy protection won't last long. All they get is lower sales, angry customers and happy pirates and crackers.

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• log4net - why would the same MyLog.Debug line not work at one point of startup, but work at another

  - by Greg

  Hi, During startup of my WinForms application I'm noting that there are a couple of points (before the MainForm renders) that do a "MyDataSet.GetInstance()". For the first one the MyLog.Debug line comes through in the VS2008 output window, but for a later one it does work and come through. What could explain this? What settings could I check at debug time to see why an output line for a MyLog.Debug line doesn't come out in the output window? namespace IntranetSync { public class MyDataSet { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MyDataSet)); public static MyDataSet GetInstance() { MyLog.Debug("MyDataSet GetInstance() ====================================="); if (myDataSet == null) { myDataSet = new MyDataSet(); } return myDataSet; } . . . PS. What I have been doing re log4net repository initialization is putting the following line as a private variables in the classes I use logging - is this OK? static class Program { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MainForm)); . . . public class Coordinator { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MainForm)); . . . public class MyDataSet { private static readonly ILog MyLog = LogManager.GetLogger(typeof(MyDataSet)); . . .

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• Events and references pattern

  - by serhio

  In a project I have the following relation between BO and GUI By e.g. G could represent a graphic with time lines, C a TimeLine curve, P - points of that curve and T the time that represents each point. Each GUI object is associated with the BO corresponding object. When T changes GUI P captures the Changed event and changes its location. So, when G should be modified, it modifies internally its objects and as result T changes, P moves and the GuiG visually changes, everything is OK. But there is an inconvenient of this architecture... BO should not be recreated, because this will breack the link between BO and GUIO. In particular, GUI P should always have the same reference of T. If in a business logic I do by e.g. P1.T = new T(this.T + 10) GUI_P1 will not move anymore, because it wait an event from the reference of former P1.T object, that does not belongs to P1 anymore. So the solution was to always modify the existing objects, not to recreate it. But here is an other inconvenient: performance. Say I have a ready newC object that should replace the older one. Instead of doing G1.C = newC I should do foreach T in foreach P in C replace with T from P from newC. Is there an other more optimal way to do it?

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• Getting a handle on GIS math, where do I start?

  - by Joshua

  I am in charge of a program that is used to create a set of nodes and paths for consumption by an autonomous ground vehicle. The program keeps track of the locations of all items in its map by indicating the item's position as being x meters north and y meters east of an origin point of 0,0. In the real world, the vehicle knows the location of the origin's lat and long, as it is determined by a dgps system and is accurate down to a couple centimeters. My program is ignorant of any lat long coordinates. It is one of my goals to modify the program to keep track of lat long coords of items in addition to an origin point and items' x,y position in relation to that origin. At first blush, it seems that I am going to modify the program to allow the lat long coords of the origin to be passed in, and after that I desire that the program will automatically calculate the lat long of every item currently in a map. From what I've researched so far, I believe that I will need to figure out the math behind converting to lat long coords from a UTM like projection where I specify the origin points and meridians etc as opposed to whatever is defined already for UTM. I've come to ask of you GIS programmers, am I on the right track? It seems to me like there is so much to wrap ones head around, and I'm not sure if the answer isn't something as simple as, "oh yea theres a conversion from meters to lat long, here" Currently, due to the nature of DGPS, the system really doesn't need to care about locations more than oh, what... 40 km? radius away from the origin. Given this, and the fact that I need to make sure that the error on my coordinates is not greater than .5 meters, do I need anything more complex than a simple lat/long to meters conversion constant? I'm knee deep in materials here. I could use some pointers about what concepts to research. Thanks much!

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• Real time embeddable http server library required

  - by Howard May

  Having looked at several available http server libraries I have not yet found what I am looking for and am sure I can't be the first to have this set of requirements. I need a library which presents an API which is 'pipelined'. Pipelining is used to describe an HTTP feature where multiple HTTP requests can be sent across a TCP link at a time without waiting for a response. I want a similar feature on the library API where my application can receive all of those request without having to send a response (I will respond but want the ability to process multiple requests at a time to reduce the impact of internal latency). So the web server library will need to support the following flow 1) HTTP Client transmits http request 1 2) HTTP Client transmits http request 2 ... 3) Web Server Library receives request 1 and passes it to My Web Server App 4) My Web Server App receives request 1 and dispatches it to My System 5) Web Server receives request 2 and passes it to My Web Server App 6) My Web Server App receives request 2 and dispatches it to My System 7) My Web Server App receives response to request 1 from My System and passes it to Web Server 8) Web Server transmits HTTP response 1 to HTTP Client 9) My Web Server App receives response to request 2 from My System and passes it to Web Server 10) Web Server transmits HTTP response 2 to HTTP Client Hopefully this illustrates my requirement. There are two key points to recognise. Responses to the Web Server Library are asynchronous and there may be several HTTP requests passed to My Web Server App with responses outstanding. Additional requirements are Embeddable into an existing 'C' application Small footprint; I don't need all the functionality available in Apache etc. Efficient; will need to support thousands of requests a second Allows asynchronous responses to requests; their is a small latency to responses and given the required request throughput a synchronous architecture is not going to work for me. Support persistent TCP connections Support use with Server-Push Comet connections Open Source / GPL support for HTTPS Portable across linux, windows; preferably more. I will be very grateful for any recommendation Best Regards

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• How to create platform independent 3D video on 3D TV via HDMI 1.4?

  - by artif

  I am writing a real-time, interactive 3D visualization program and at each point in the program, I can compute 2 images (bitmaps) that are meant to look 3D together by means of stereoscopy. How do I get my program to display the image pairs such that they look 3D on a 3D TV? Is there a platform independent way of accomplishing it? (By platform I mean independent of GPU brand, operating system, 3D TV vendor, etc.) If not, which is preferable-- to lock in by GPU, OS, or 3D TV? I suppose I need to be using an HDMI 1.4 cable with the 3D TV? HDMI 1.4 can encode stereoscopy via side-by-side method. But how do I send such an encoded signal to the monitor? What kind of libraries do I use for this sort of thing? Windows DirectShow? If DirectShow is correct, is there a cross platform equivalent available? If anyone asks, yes I have seen this question: http://stackoverflow.com/questions/2811350/generating-3d-tv-stereoscopic-output-programmatically. However, correct me if I am wrong, it does not appear to be what I'm looking for. I do not have an OpenGL or Direct3D program that generates polygons, for which a Nvidia card can do ad-hoc impromptu stereoscopy simply by rendering the scene from 2 slightly offset points of view and then displaying those 2 images on the monitor-- my program already has those image pairs and needs to display them (and they are not the result of rendering polygons). Btw, I have never done any major multimedia programming before and know very little about HDMI, Direct Show, 3D TVs, etc so pardon me if any parts of this question did not make any sense at all.

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• using load instead of other I/O command

  - by Amadou

  How can I modify this program using load-ascii command to read (x,y)? n=0; sum_x = 0; sum_y = 0; sum_x2 = 0; sum_xy = 0; disp('This program performs a least-squares fit of an'); disp('input data set to a straight line. Enter the name'); disp('of the file containing the input (x,y) pairs: '); filename = input(' ','s'); [fid,msg] = fopen(filename,'rt'); if fid<0 disp(msg); else [in,count]=fscanf(fid, '%g %g',2); while ~feof(fid) x=in(1); y=in(2); n=n+1; sum_x=sum_x+x; sum_y=sum_y+y; sum_x2=sum_x2+x.^2; sum_xy=sum_xy+x*y; [in,count] = fscanf(fid, '%f',[1 2]); end fclose(fid); x_bar = sum_x / n; y_bar = sum_y / n; slope = (sum_xy - sum_x*y_bar) / (sum_x2 - sum_x*x_bar); y_int = y_bar - slope * x_bar; fprintf('Regression coefficients for the least-squares line:\n'); fprintf('Slope (m) =%12.3f\n',slope); fprintf('Intercept (b) =%12.3f\n',y_int); fprintf('No of points =%12d\n',n); end

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• Custom Solr sorting

  - by Tom

  Hello everyone, I've been asked to do an evaluation of Solr as an alternative for a commercial search engine. The application now has a very particular way of sorting results using something called "buckets". I'll try to explain with a bit of details: In the interface they have 2 fields: "what" and "where". Both fields are actually sets of fields (what = category, name, contact info... and where= country, state, region, city...) so the copyfield feature of Solr immediately comes to mind. Now based on the field generated the actual match the result should end up in a specific bucket. In particular the first bucket contains all the result documents that have an exact match on the category field, in the second bucket all exact matches on name, the third partial matches on category, the fourth partial matches on name, the fifth matches on contact info etc... Then within each of those first tier buckets all results are placed in second tier buckets depending on what location was matched: city, then region, then province and so on. To even complicate things more there is also a third tier bucket where results are placed according to the value of a ranking field: all documents with the value 1 in the ranking field go in bucket 1 and so on. And finally results should be randomized in the third tier bucket... On top of this they obviously want support for facets and paging. My apologies for the long mail but I would greatly appreciate feedback and/or suggestions. I'm aware that this that this is a very particular problem but everything that points me in the right direction is helpful. Cheers, Tom

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• How do I use InputType=numberDecimal with the "phone" soft keypad?

  - by Adam Dunn

  For an EditText box, the user should only be entering valid numbers, so I am using android:inputType="numberDecimal". Unfortunately, the soft keyboard that Android brings up has numbers only along the top row, while the next three rows have various other symbols (dollar sign, percent sign, exclamation mark, space, etc). Since the numberDecimal only accepts numbers 0-9, negative sign, and decimal point, it would make more sense to use the "phone" soft keyboard (0-9 in a 3x3 grid, plus some other symbols). This would make the buttons larger and easier to hit (since it's a 4x4 grid rather than a 10x4 grid in the same screen area). Unfortunately, using android:inputType="phone" allows non-numeric characters such as parentheses I have attempted to use android:inputType="numberDecimal|phone", but the numberDecimal aspect of the bit flag seems to be ignored. I have also tried using android:inputType="phone" in combination with android:digits="0123456789-.", but that still allows multiple negative signs or decimal points (inputType="number" has really good error checking for things like that, and won't let the user even type it in). I have also tried using android:inputType="phone" in the xml layout file, while using a DigitsKeyListener in the java code, but then that just uses the default number soft keyboard (the one that has numbers only along top row) (it appears to set InputType.TYPE_CLASS_NUMBER, which voids the InputType.TYPE_CLASS_PHONE set by the xml layout). Writing a custom IME wouldn't work, since the user would have to select the IME as a global option outside the app. Is there any way to use the "phone" style soft keyboard while also using the "number" restrictions on what is entered?

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• invasive vs non-invasive ref-counted pointers in C++

  - by anon

  For the past few years, I've generally accepted that if I am going to use ref-counted smart pointers invasive smart pointers is the way to go -- However, I'm starting to like non-invasive smart pointers due to the following: I only use smart pointers (so no Foo* lying around, only Ptr) I'm starting to build custom allocators for each class. (So Foo would overload operator new). Now, if Foo has a list of all Ptr (as it easily can with non-invasive smart pointers). Then, I can avoid memory fragmentation issues since class Foo move the objects around (and just update the corresponding Ptr). The only reason why this Foo moving objects around in non-invasive smart pointers being easier than invasive smart pointers is: In non-invasive smart pointers, there is only one pointer that points to each Foo. In invasive smart pointers, I have no idea how many objects point to each Foo. Now, the only cost of non-invasive smart pointers ... is the double indirection. [Perhaps this screws up the caches]. Does anyone have a good study of expensive this extra layer of indirection is?

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• What is the purpose of the s==NULL case for mbrtowc?

  - by R..

  mbrtowc is specified to handle a NULL pointer for the s (multibyte character pointer) argument as follows: If s is a null pointer, the mbrtowc() function shall be equivalent to the call: mbrtowc(NULL, "", 1, ps) In this case, the values of the arguments pwc and n are ignored. As far as I can tell, this usage is largely useless. If ps is not storing any partially-converted character, the call will simply return 0 with no side effects. If ps is storing a partially-converted character, then since '\0' is not valid as the next byte in a multibyte sequence ('\0' can only be a string terminator), the call will return (size_t)-1 with errno==EILSEQ. and leave ps in an undefined state. The intended usage seems to have been to reset the state variable, particularly when NULL is passed for ps and the internal state has been used, analogous to mbtowc's behavior with stateful encodings, but this is not specified anywhere as far as I can tell, and it conflicts with the semantics for mbrtowc's storage of partially-converted characters (if mbrtowc were to reset state when encountering a 0 byte after a potentially-valid initial subsequence, it would be unable to detect this dangerous invalid sequence). If mbrtowc were specified to reset the state variable only when s is NULL, but not when it points to a 0 byte, a desirable state-reset behavior would be possible, but such behavior would violate the standard as written. Is this a defect in the standard? As far as I can tell, there is absolutely no way to reset the internal state (used when ps is NULL) once an illegal sequence has been encountered, and thus no correct program can use mbrtowc with ps==NULL.

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• How do I link one listview to another to create a football league table?

  - by Richard Nixon

  Hi I am creating a football system in windows forms c#. I have one listview where data is entered. I have 4 columns, 2 with team names linked to combo boxes and 2 with the scores linked to numericupdown controls. There are 3 buttons to add the results, Remove and clear. the code is below: private void addButton_Click(object sender, EventArgs e) { { ListViewItem item = new ListViewItem(comboBox1.SelectedItem.ToString()); item.SubItems.Add(numericUpDown1.Value.ToString()); item.SubItems.Add(numericUpDown2.Value.ToString()); item.SubItems.Add(comboBox2.SelectedItem.ToString()); listView1.Items.Add(item); } } private void clearButton_Click(object sender, EventArgs e) { listView1.Items.Clear(); } private void removeButton_Click(object sender, EventArgs e) { foreach (ListViewItem itemSelected in listView1.SelectedItems) { listView1.Items.Remove(itemSelected); } } I have another listview that i want to link the first one to. The second one is a usual english football league table and i want to use maths to add up the games played and the points etc. please help. cheers

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• WPF: How to bind and update display with DataContext

  - by Am

  I'm trying to do the following thing: I have a TabControl with several tabs. Each TabControlItem.Content points to PersonDetails which is a UserControl Each BookDetails has a dependency property called IsEditMode I want a control outside of the TabControl , named ToggleEditButton, to be updated whenever the selected tab changes. I thought I could do this by changing the ToggleEditButton data context, by it doesn't seem to work (but I'm new to WPF so I might way off) The code changing the data context: private void tabControl1_SelectionChanged(object sender, SelectionChangedEventArgs e) { if (e.Source is TabControl) { if (e.Source.Equals(tabControl1)) { if (tabControl1.SelectedItem is CloseableTabItem) { var tabItem = tabControl1.SelectedItem as CloseableTabItem; RibbonBook.DataContext = tabItem.Content as BookDetails; ribbonBar.SelectedTabItem = RibbonBook; } } } } The DependencyProperty under BookDetails: public static readonly DependencyProperty IsEditModeProperty = DependencyProperty.Register("IsEditMode", typeof (bool), typeof (BookDetails), new PropertyMetadata(true)); public bool IsEditMode { get { return (bool)GetValue(IsEditModeProperty); } set { SetValue(IsEditModeProperty, value); SetValue(IsViewModeProperty, !value); } } And the relevant XAML: <odc:RibbonTabItem Title="Book" Name="RibbonBook"> <odc:RibbonGroup Title="Details" Image="img/books2.png" IsDialogLauncherVisible="False"> <odc:RibbonToggleButton Content="Edit" Name="ToggleEditButton" odc:RibbonBar.MinSize="Medium" SmallImage="img/edit_16x16.png" LargeImage="img/edit_32x32.png" Click="Book_EditDetails" IsChecked="{Binding Path=IsEditMode, Mode=TwoWay}"/> ... There are two things I want to accomplish, Having the button reflect the IsEditMode for the visible tab, and have the button change the property value with no code behind (if posible) Any help would be greatly appriciated.

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• Unable to persist objects in GAE JDO

  - by Basil Dsouza

  Hello Guys, I am completely fresh to both JDO and GAE, and have been struggling to get my data layer to persist any code at all! The issues I am facing may be very simple, but I just cant seem to find any a way no matter what solution I try. Firstly the problem: (Slightly simplified, but still contains all the info necessary) My data model is as such: User: (primary key) String emailID String firstName Car: (primary key) User user (primary key) String registration String model This was the initial datamodel. I implemented a CarPK object to get a composite primary key of the User and the registration. However that ran into a variety of issues. (Which i will save for another time/question) I then changed the design as such: User: (Unchanged) Car: (primary key) String fauxPK (here fauxPK = user.getEmailID() + SEP + registration) User user String registration String model This works fine for the user, and it can insert and retrieve user objects. However when i try to insert a Car Object, i get the following error: "Cannot have a java.lang.String primary key and be a child object" Found the following helpful link about it: http://stackoverflow.com/questions/2063467/persist-list-of-objects Went to the link suggested there, that explains how to create Keys, however they keep talking about "Entity Groups" and "Entity Group Parents". But I cant seem to find any articles or sites that explain what are "Entity Group"s or an "Entity Group Parents" I could try fiddling around some more to figure out if i can store an object somehow, But I am running sort on patience and also would rather understand and implement than vice versa. So i would appreciate any docs (even if its huge) that covers all these points, and preferably has some examples that go beyond the very basic data modeling. And thanks for reading such a long post :)

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• Event feed implementation - will it scale?

  - by SlappyTheFish

  Situation: I am currently designing a feed system for a social website whereby each user has a feed of their friends' activities. I have two possible methods how to generate the feeds and I would like to ask which is best in terms of ability to scale. Events from all users are collected in one central database table, event_log. Users are paired as friends in the table friends. The RDBMS we are using is MySQL. Standard method: When a user requests their feed page, the system generates the feed by inner joining event_log with friends. The result is then cached and set to timeout after 5 minutes. Scaling is achieved by varying this timeout. Hypothesised method: A task runs in the background and for each new, unprocessed item in event_log, it creates entries in the database table user_feed pairing that event with all of the users who are friends with the user who initiated the event. One table row pairs one event with one user. The problems with the standard method are well known – what if a lot of people's caches expire at the same time? The solution also does not scale well – the brief is for feeds to update as close to real-time as possible The hypothesised solution in my eyes seems much better; all processing is done offline so no user waits for a page to generate and there are no joins so database tables can be sharded across physical machines. However, if a user has 100,000 friends and creates 20 events in one session, then that results in inserting 2,000,000 rows into the database. Question: The question boils down to two points: Is this worst-case scenario mentioned above problematic, i.e. does table size have an impact on MySQL performance and are there any issues with this mass inserting of data for each event? Is there anything else I have missed?

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• What is an elegant way to solve this max and min problem in Ruby or Python?

  - by ????

  The following can be done by step by step, somewhat clumsy way, but I wonder if there are elegant method to do it. There is a page: http://www.mariowiki.com/Mario_Kart_Wii, where there are 2 tables... there is Mario - 6 2 2 3 - - Luigi 2 6 - - - - - Diddy Kong - - 3 - 3 - 5 [...] The name "Mario", etc are the Mario Kart Wii character names. The numbers are for bonus points for: Speed Weight Acceleration Handling Drift Off-Road Mini-Turbo and then there is table 2 Standard Bike S 39 21 51 51 54 43 48 Out Bullet Bike 53 24 32 35 67 29 67 In Bubble Bike / Jet Bubble 48 27 40 40 45 35 37 In [...] These are also the characteristics for the Bike or Kart. I wonder what's the most elegant solution for finding all the maximum combinations of Speed, Weight, Acceleration, etc, and also for the minimum, either by directly using the HTML on that page or copy and pasting the numbers into a text file. Actually, in that character table, Mario to Bower Jr are all medium characters, Baby Mario to Dry Bones are small characters, and the rest are all big characters, except the small, medium, or large Mii are just as what the name says. Small characters can only ride small bike or small kart, and so forth for medium and large.

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• Getting zeros between data while reading a binary file in C

  - by indiajoe

  I have a binary data which I am reading into an array of long integers using a C programme. hexdump of the binary data shows, that after first few data points , it starts again at a location 20000 hexa adresses away. hexdump output is as shown below. 0000000 0000 0000 0000 0000 0000 0000 0000 0000 * 0020000 0000 0000 0053 0000 0064 0000 006b 0000 0020010 0066 0000 0068 0000 0066 0000 005d 0000 0020020 0087 0000 0059 0000 0062 0000 0066 0000 ........ and so on... But when I read it into an array 'data' of long integers. by the typical fread command fread(data,sizeof(*data),filelength/sizeof(*data),fd); It is filling up with all zeros in my data array till it reaches the 20000 location. After that it reads in data correctly. Why is it reading regions where my file is not there? Or how will I make it read only my file, not anything inbetween which are not in file? I know it looks like a trivial problem, but I cannot figure it out even after googling one night.. Can anyone suggest me where I am doing it wrong? Other Info : I am working on a gnu/linux machine. (slax-atma distro to be specific) My C compiler is gcc.

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• NES Programming - Nametables?

  - by Jeffrey Kern

  Hello everyone, I'm wondering about how the NES displays its graphical muscle. I've researched stuff online and read through it, but I'm wondering about one last thing: Nametables. Basically, from what I've read, each 8x8 block in a NES nametable points to a location in the pattern table, which holds graphic memory. In addition, the nametable also has an attribute table which sets a certain color palette for each 16x16 block. They're linked up together like this: (assuming 16 8x8 blocks) Nametable, with A B C D = pointers to sprite data: ABBB CDCC DDDD DDDD Attribute table, with 1 2 3 = pointers to color palette data, with < referencing value to the left, ^ above, and ' to the left and above: 1<2< ^'^' 3<3< ^'^' So, in the example above, the blocks would be colored as so 1A 1B 2B 2B 1C 1D 2C 2C 3D 3D 3D 3D 3D 3D 3D 3D Now, if I have this on a fixed screen - it works great! Because the NES resolution is 256x240 pixels. Now, how do these tables get adjusted for scrolling? Because Nametable 0 can scroll into Nametable 1, and if you keep scrolling Nametable 0 will wrap around again. That I get. But what I don't get is how to scroll the attribute table wraps around as well. From what I've read online, the 16x16 blocks it assigns attributes for will cause color distortions on the edge tiles of the screen (as seen when you scroll left to right and vice-versa in SMB3). The concern I have is that I understand how to scroll the nametables, but how do you scroll the attribute table? For intsance, if I have a green block on the left side of the screen, moving the screen to right should in theory cause the tiles to the right to be green as well until they move more into frame, to which they'll revert to their normal colors.

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• Binding update on adds news series to WPF Toolkit chart (instead of replacing/updating series)

  - by Mal Ross

  I'm currently recoding a bar chart in my app to make use of the Chart class in the WPF Toolkit. Using MVVM, I'm binding the ItemsSource of a ColumnSeries in my chart to a property on my viewmodel. Here's the relevant XAML: <charting:Chart> <charting:ColumnSeries ItemsSource="{Binding ScoreDistribution.ClassScores}" IndependentValuePath="ClassName" DependentValuePath="Score"/> </charting:Chart> And the property on the viewmodel: // NB: viewmodel derived from Josh Smith's BindableObject public class ExamResultsViewModel : BindableObject { // ... private ScoreDistributionByClass _scoreDistribution; public ScoreDistributionByClass ScoreDistribution { get { return _scoreDistribution; } set { if (_scoreDistribution == value) { return; } _scoreDistribution = value; RaisePropertyChanged(() => ScoreDistribution); } } However, when I update the ScoreDistribution property (by setting it to a new ScoreDistribution object), the chart gets an additional series (based on the new ScoreDistribution) as well as keeping the original series (based on the previous ScoreDistribution). To illustrate this, here are a couple of screenshots showing the chart before an update (with a single data point in ScoreDistribution.ClassScores) and after it (now with 3 data points in ScoreDistribution.ClassScores): Now, I realise there are other ways I could be doing this (e.g. changing the contents of the original ScoreDistribution object rather than replacing it entirely), but I don't understand why it's going wrong in its current form. Can anyone help?

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• GridView will not update underlying data source

  - by John Christensen

  So I'm been pounding on this problem all day. I've got a LinqDataSource that points to my model and a GridView that consumes it. When I attempt to do an update on the GridView, it does not update the underlying data source. I thought it might have to do with the LinqDataSource, so I added a SqlDataSource and the same thing happens. The aspx is as follows (the code-behind page is empty): <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="Data Source=devsql32;Initial Catalog=Steam;Persist Security Info=True;" ProviderName="System.Data.SqlClient" SelectCommand="SELECT [LangID], [Code], [Name] FROM [Languages]" UpdateCommand="UPDATE [Languages] SET [Code]=@Code WHERE [LangID]=@LangId"> </asp:SqlDataSource> <asp:GridView ID="_languageGridView" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="LangId" DataSourceID="SqlDataSource1"> <Columns> <asp:CommandField ShowDeleteButton="True" ShowEditButton="True" /> <asp:BoundField DataField="LangId" HeaderText="Id" ReadOnly="True" /> <asp:BoundField DataField="Code" HeaderText="Code" /> <asp:BoundField DataField="Name" HeaderText="Name" /> </Columns> </asp:GridView> <asp:LinqDataSource ID="_languageDataSource" ContextTypeName="GeneseeSurvey.SteamDatabaseDataContext" runat="server" TableName="Languages" EnableInsert="True" EnableUpdate="true" EnableDelete="true"> </asp:LinqDataSource> What in the world am I missing here? This problem is driving me insane.

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