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  • Suggestions: Anti-Pattern counter-examples

    - by Tom W
    It doesn't seem that this exact question has been asked before, so I'll fire away: Most of us are familiar with the concept of an anti-pattern. However, avoiding implementation of anti-patterns can in principle swing too far the other way and cause problems itself. As an example, "Design by Committee" has a counter-example that I'd call "Design by Maverick" - wherein the design of an important feature is handed off to an individual to do what they think best, with the intention of reviewing their work later and deciding whether it should be finalised or go through another iteration. This takes much longer in practice as the rest of the team are occupied by other things, and can end up with a feature that's useful to nobody, particularly if the Maverick is not themselves an experienced end-user. Does anyone have any more examples of anti-pattern counter-examples?

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  • How to learn to program C the right way

    - by sfactor
    i have been programming in C/C++ for my academic courses a lot and was under the impression i had a pretty good grasp of it. but lately i had to work in a bluetooth application that had a server and client implementation in a Linux box and an embedded system. i learned bluez bluetooth API, socket/network programming and coded it. however i ran into a lot of problems with memory leaks and segmentation faults and other memory related errors along the way.as the code grew more complex i all but lost control of the pointers and threads and sockets. this got me wondering that i had a lot to learn that they didn't say in the basic C/C++ books. so i wanted to ask for the resources that are available that'll help be code better in a professional way in C/C++ .especially for the Linux/Mac environment (gcc compiler).

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  • Does "Value Restriction" mean that there is no higher order functional programming?

    - by Sadache
    Does "Value Restriction" mean that there is no higher order functional programming? I have a problem that each time I try to do a bit of HOP I get caught by a VR error. Example: let simple (s:string)= fun rq->1 let oops= simple "" type 'a SimpleType= F of (int ->'a-> 'a) let get a = F(fun req -> id) let oops2= get "" and I would like to know whether it is a problem of a prticular implementation of VR or it is a general problem that has no solution in a mutable type-infered language that doesn't include mutation in the type system.

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  • EXC_BAD_ACCESS at UITableView on IOS

    - by Suprie
    Hi all, When scrolling through table, my application crash and console said it was EXC_BAD_ACCESS. I've look everywhere, and people suggest me to use NSZombieEnabled on my executables environment variables. I've set NSZombieEnabled, NSDebugEnabled, MallocStackLogging and MallocStackLoggingNoCompact to YES on my executables. But apparently i still can't figure out which part of my program that cause EXC_BAD_ACCESS. This is what my console said [Session started at 2010-12-21 21:11:21 +0700.] GNU gdb 6.3.50-20050815 (Apple version gdb-1510) (Wed Sep 22 02:45:02 UTC 2010) Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "x86_64-apple-darwin".sharedlibrary apply-load-rules all Attaching to process 9335. TwitterSearch(9335) malloc: recording malloc stacks to disk using standard recorder TwitterSearch(9335) malloc: process 9300 no longer exists, stack logs deleted from /tmp/stack-logs.9300.TwitterSearch.suirlR.index TwitterSearch(9335) malloc: stack logs being written into /tmp/stack- logs.9335.TwitterSearch.tQJAXk.index 2010-12-21 21:11:25.446 TwitterSearch[9335:207] View Did Load Program received signal: “EXC_BAD_ACCESS”. And this is when i tried to type backtrace on gdb : Program received signal: “EXC_BAD_ACCESS”. (gdb) backtrace #0 0x00f20a67 in objc_msgSend () #1 0x0565cd80 in ?? () #2 0x0033b7fa in -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:withIndexPath:] () #3 0x0033177f in -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:] () #4 0x00346450 in -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow:] () #5 0x0033e538 in -[UITableView layoutSubviews] () #6 0x01ffc451 in -[CALayer layoutSublayers] () #7 0x01ffc17c in CALayerLayoutIfNeeded () #8 0x01ff537c in CA::Context::commit_transaction () #9 0x01ff50d0 in CA::Transaction::commit () #10 0x020257d5 in CA::Transaction::observer_callback () #11 0x00d9ffbb in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ () #12 0x00d350e7 in __CFRunLoopDoObservers () #13 0x00cfdbd7 in __CFRunLoopRun () #14 0x00cfd240 in CFRunLoopRunSpecific () #15 0x00cfd161 in CFRunLoopRunInMode () #16 0x01a73268 in GSEventRunModal () #17 0x01a7332d in GSEventRun () #18 0x002d642e in UIApplicationMain () #19 0x00001d4e in main (argc=1, argv=0xbfffee34) at /Users/suprie/Documents/Projects/Self/cocoa/TwitterSearch/main.m:14 I really appreciate for any clue to help me debug my application. EDIT this is the Header file of table #import <UIKit/UIKit.h> @interface TwitterTableViewController : UITableViewController { NSMutableArray *twitters; } @property(nonatomic,retain) NSMutableArray *twitters; @end and the implementation file #import "TwitterTableViewController.h" @implementation TwitterTableViewController @synthesize twitters; #pragma mark - #pragma mark Table view data source - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { // Return the number of rows in the section. return [twitters count]; } - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { return 90.0f; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { const NSInteger TAG_IMAGE_VIEW = 1001; const NSInteger TAG_TWEET_VIEW = 1002; const NSInteger TAG_FROM_VIEW = 1003; static NSString *CellIdentifier = @"Cell"; UIImageView *imageView; UILabel *tweet; UILabel *from; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; // Image imageView = [[[[UIImageView alloc] initWithFrame:CGRectMake(5.0f, 5.0f, 60.0f, 60.0f)] autorelease] retain]; [cell.contentView addSubview:imageView]; imageView.tag = TAG_IMAGE_VIEW; // Tweet tweet = [[[UILabel alloc] initWithFrame:CGRectMake(105.0f, 5.0f, 200.0f, 50.0f)] autorelease]; [cell.contentView addSubview:tweet]; tweet.tag = TAG_TWEET_VIEW; tweet.numberOfLines = 2; tweet.font = [UIFont fontWithName:@"Helvetica" size:12]; tweet.textColor = [UIColor blackColor]; tweet.backgroundColor = [UIColor clearColor]; // From from = [[[UILabel alloc] initWithFrame:CGRectMake(105.0f, 55.0, 200.0f, 35.0f)] autorelease]; [cell.contentView addSubview:from]; from.tag = TAG_FROM_VIEW; from.numberOfLines = 1; from.font = [UIFont fontWithName:@"Helvetica" size:10]; from.textColor = [UIColor blackColor]; from.backgroundColor = [UIColor clearColor]; } // Configure the cell... NSMutableDictionary *twitter = [twitters objectAtIndex:(NSInteger) indexPath.row]; // cell.text = [twitter objectForKey:@"text"]; tweet.text = (NSString *) [twitter objectForKey:@"text"]; tweet.hidden = NO; from.text = (NSString *) [twitter objectForKey:@"from_user"]; from.hidden = NO; NSString *avatar_url = (NSString *)[twitter objectForKey:@"profile_image_url"]; NSData * imageData = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: avatar_url]]; imageView.image = [UIImage imageWithData: imageData]; imageView.hidden = NO; return cell; } #pragma mark - #pragma mark Table view delegate - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSMutableDictionary *twitter = [twitters objectAtIndex:(NSInteger)indexPath.row]; NSLog(@"Twit ini kepilih :%@", [twitter objectForKey:@"text"]); } #pragma mark - #pragma mark Memory management - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; } - (void)viewDidUnload { } - (void)dealloc { [super dealloc]; } @end

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  • Loose Coupling of Components

    - by David
    I have created a class library (assembly) that provides messaging, email and sms. This class library defines an interface IMessenger which the classes EmailMessage and SmsMessage both implement. I see this is a general library that would be part of my infrastructure layer and would / can be used across any development. Now, in my application layer I have a class that requires to use a messaging component, I obviously want to use the messaging library that I have created. Additionally, I will be using an IoC container (Spring.net) to allow me to inject my implementation i.e. either email or sms. Therefore, I want to program against an interface in my application layer class, do I then need to reference my message class library from my application layer class? Is this tightly coupling my application layer class to my message class library? Should I be defining the interface - IMessenger in a seperate library? Or should I be doing something else?

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  • Working with OAuth on Google with Python

    - by Dan Loewenherz
    I'm having a very frustrating time creating a valid signature for Google's OAuth implementation. I have narrowed it all down to the fact that my signature-generation code has an error of some sort; what it is I have no idea. This is the signature base string in its entirety: GET&https%3A%2F%2Fwww.google.com%2Faccounts%2FOAuthGetAccessToken&oauth_consumer_key%3Ddlosplayground.appspot.com%26oauth_nonce%3D72815d55697cb24301fab03e1f7f1d66%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1274327867%26oauth_token%3D4%252FX2cZ54JuseQbgRwzTBzZ7lqIwqof%26oauth_verifier%3Dihf0F2Fx%252FpnCmwbVQnk2xMre%26oauth_version%3D1.0 The OAuth Playground returns an oauth_signature of gF8qAfWjpdKjKb4KR%2FvA2Gy0vhU%3D. My code gives me ikMpIKJQJ58jseg%2BKPBTecjmYPE%3D, so obviously I'm doing something wrong. Here's my signature generation code (equivalent to that of the standard oauth.py library): binascii.b2a_base64(hmac.new(CONSUMER_SECRET, BASE_STRING, hashlib.sha1).digest())[:-1] Any thoughts?

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  • c99 goto past initialization

    - by R Samuel Klatchko
    While debugging a crash, I came across this issue in some code: int func() { char *p1 = malloc(...); if (p1 == NULL) goto err_exit; char *p2 = malloc(...); if (p2 == NULL) goto err_exit; ... err_exit: free(p2); free(p1); return -1; } The problem occurs when the first malloc fails. Because we jump across the initialization of p2, it contains random data and the call to free(p2) can crash. I would expect/hope that this would be treated the same way as in C++ where the compiler does not allow a goto to jump across an initialization. My question: is jumping across an initialization allowed by the standard or is this a bug in gcc's implementation of c99?

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  • New to C# and trying to use a global variable

    - by Andrew G. Johnson
    Is it possible to use global variables in C#? I'm coming from mainly a PHP background so variables are either accessible everywhere or just a global definition away. My main issue is I have a User class that I built myself to wrap around the current users table on my company's database. I am defining it in the MasterPage but can't seem to access it from the actual pages (I don't know if there's a better word to describe them but they are the pages that inherit the styles and format from the MasterPage) Any general tips or implementation practices for me? EDIT: here's some code snippets of what I'm trying to do: Site.master.cs public partial class SiteMaster : System.Web.UI.MasterPage { public User user = new User(); } logout.aspx <%@ Page Title="" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="logout.aspx.cs" Inherits="logout" %> <%@ MasterType virtualPath="~/Site.master"%> logout.aspx.cs public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { User user = Master.user; } }

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  • Choosing the non-empty Monoid

    - by Nikita Volkov
    I need a function which will choose a non-empty monoid. For a list this will mean the following behaviour: > [1] `mor` [] [1] > [1] `mor` [2] [1] > [] `mor` [2] [2] Now, I've actually implemented it but am wondering wether there exists some standard alternative, because it seems to be a kind of a common case. Unfortunately Hoogle doesn't help. Here's my implementation: mor :: (Eq a, Monoid a) => a -> a -> a mor a b = if a /= mempty then a else b

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  • Will there be IQueryable-like additions to IObservable? (.NET Rx)

    - by Jason
    The new IObservable/IObserver frameworks in the System.Reactive library coming in .NET 4.0 are very exciting (see this and this link). It may be too early to speculate, but will there also be a (for lack of a better term) IQueryable-like framework built for these new interfaces as well? One particular use case would be to assist in pre-processing events at the source, rather than in the chain of the receiving calls. For example, if you have a very 'chatty' event interface, using the Subscribe().Where(...) will receive all events through the pipeline and the client does the filtering. What I am wondering is if there will be something akin to IQueryableObservable, whereby these LINQ methods will be 'compiled' into some 'smart' Subscribe implementation in a source. I can imagine certain network server architectures that could use such a framework. Or how about an add-on to SQL Server (or any RDBMS for that matter) that would allow .NET code to receive new data notifications (triggers in code) and would need those notifications filtered server-side.

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  • CUDA small kernel 2d convolution - how to do it

    - by paulAl
    I've been experimenting with CUDA kernels for days to perform a fast 2D convolution between a 500x500 image (but I could also vary the dimensions) and a very small 2D kernel (a laplacian 2d kernel, so it's a 3x3 kernel.. too small to take a huge advantage with all the cuda threads). I created a CPU classic implementation (two for loops, as easy as you would think) and then I started creating CUDA kernels. After a few disappointing attempts to perform a faster convolution I ended up with this code: http://www.evl.uic.edu/sjames/cs525/final.html (see the Shared Memory section), it basically lets a 16x16 threads block load all the convolution data he needs in the shared memory and then performs the convolution. Nothing, the CPU is still a lot faster. I didn't try the FFT approach because the CUDA SDK states that it is efficient with large kernel sizes. Whether or not you read everything I wrote, my question is: how can I perform a fast 2D convolution between a relatively large image and a very small kernel (3x3) with CUDA?

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  • Core Animation bad access on device

    - by user1595102
    I'm trying to do a frame by frame animation with CAlayers. I'm doing this with this tutorial http://mysterycoconut.com/blog/2011/01/cag1/ but everything works with disable ARC, when I'm try to rewrite code with ARC, it's works on simulator perfectly but on device I got a bad access memory. Layer Class interface #import <Foundation/Foundation.h> #import <QuartzCore/QuartzCore.h> @interface MCSpriteLayer : CALayer { unsigned int sampleIndex; } // SampleIndex needs to be > 0 @property (readwrite, nonatomic) unsigned int sampleIndex; // For use with sample rects set by the delegate + (id)layerWithImage:(CGImageRef)img; - (id)initWithImage:(CGImageRef)img; // If all samples are the same size + (id)layerWithImage:(CGImageRef)img sampleSize:(CGSize)size; - (id)initWithImage:(CGImageRef)img sampleSize:(CGSize)size; // Use this method instead of sprite.sampleIndex to obtain the index currently displayed on screen - (unsigned int)currentSampleIndex; @end Layer Class implementation @implementation MCSpriteLayer @synthesize sampleIndex; - (id)initWithImage:(CGImageRef)img; { self = [super init]; if (self != nil) { self.contents = (__bridge id)img; sampleIndex = 1; } return self; } + (id)layerWithImage:(CGImageRef)img; { MCSpriteLayer *layer = [(MCSpriteLayer*)[self alloc] initWithImage:img]; return layer ; } - (id)initWithImage:(CGImageRef)img sampleSize:(CGSize)size; { self = [self initWithImage:img]; if (self != nil) { CGSize sampleSizeNormalized = CGSizeMake(size.width/CGImageGetWidth(img), size.height/CGImageGetHeight(img)); self.bounds = CGRectMake( 0, 0, size.width, size.height ); self.contentsRect = CGRectMake( 0, 0, sampleSizeNormalized.width, sampleSizeNormalized.height ); } return self; } + (id)layerWithImage:(CGImageRef)img sampleSize:(CGSize)size; { MCSpriteLayer *layer = [[self alloc] initWithImage:img sampleSize:size]; return layer; } + (BOOL)needsDisplayForKey:(NSString *)key; { return [key isEqualToString:@"sampleIndex"]; } // contentsRect or bounds changes are not animated + (id < CAAction >)defaultActionForKey:(NSString *)aKey; { if ([aKey isEqualToString:@"contentsRect"] || [aKey isEqualToString:@"bounds"]) return (id < CAAction >)[NSNull null]; return [super defaultActionForKey:aKey]; } - (unsigned int)currentSampleIndex; { return ((MCSpriteLayer*)[self presentationLayer]).sampleIndex; } // Implement displayLayer: on the delegate to override how sample rectangles are calculated; remember to use currentSampleIndex, ignore sampleIndex == 0, and set the layer's bounds - (void)display; { if ([self.delegate respondsToSelector:@selector(displayLayer:)]) { [self.delegate displayLayer:self]; return; } unsigned int currentSampleIndex = [self currentSampleIndex]; if (!currentSampleIndex) return; CGSize sampleSize = self.contentsRect.size; self.contentsRect = CGRectMake( ((currentSampleIndex - 1) % (int)(1/sampleSize.width)) * sampleSize.width, ((currentSampleIndex - 1) / (int)(1/sampleSize.width)) * sampleSize.height, sampleSize.width, sampleSize.height ); } @end I create the layer on viewDidAppear and start animate by clicking on button, but after init I got a bad access error -(void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; NSString *path = [[NSBundle mainBundle] pathForResource:@"mama_default.png" ofType:nil]; CGImageRef richterImg = [UIImage imageWithContentsOfFile:path].CGImage; CGSize fixedSize = animacja.frame.size; NSLog(@"wid: %f, heigh: %f", animacja.frame.size.width, animacja.frame.size.height); NSLog(@"%f", animacja.frame.size.width); richter = [MCSpriteLayer layerWithImage:richterImg sampleSize:fixedSize]; animacja.hidden = 1; richter.position = animacja.center; [self.view.layer addSublayer:richter]; } -(IBAction)animacja:(id)sender { if ([richter animationForKey:@"sampleIndex"]) {NSLog(@"jest"); } if (! [richter animationForKey:@"sampleIndex"]) { CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"sampleIndex"]; anim.fromValue = [NSNumber numberWithInt:0]; anim.toValue = [NSNumber numberWithInt:22]; anim.duration = 4; anim.repeatCount = 1; [richter addAnimation:anim forKey:@"sampleIndex"]; } } Have you got any idea how to fix it? Thanks a lot.

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  • Twitter @Anywhere oauth_bridge_code

    - by AngelCabo
    I'm having trouble with Twitter's implementation of an oauth_bridge_code for the @anywhere api. I've seen a few walkthrough's on how to use this functionality but I can't seem to get the request to work for me. I'm using Ruby on Rails with the oauth gem. My code is as follows: def callback consumer = OAuth::Consumer.new(APP_CONFIG['twitter_key'], APP_CONFIG['twitter_secret'], :site => "http://api.twitter.com", :request_token_path => "/oauth/request_token", :authorize_path => "/oauth/authorize", :access_token_path => "/oauth/access_token", :http_method => :post) request = OAuth::AccessToken.new consumer json = request.post("https://api.twitter.com/oauth/access_token?oauth_bridge_code=#{params[:oauth_bridge_code]}") end I keep getting 401 unauthorized responses from the signed post request even though this is supposed to be working according to this walkthrough: http://blog.abrah.am/2010/09/using-twitter-anywhere-bridge-codes.html and a presentation from Matt Harris on slideshare. Any ideas on what I'm doing wrong (besides possibly trying to hit functionality that may not be in place)? Greatly appreciated!

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  • Java/MySQL: Working with data in classes

    - by skiwi
    What is the best way to deal with accessing/modifying tables in a database? I have read about the Data Access Object approach, but none of the resources I have found so far indicate a clear implementation of it. So assume you have a database with a table called accounts that has columns id, name, password and email. How would you properly access it within Java? I mean most people know how to do SQL statements, but that is not really the point. I hope people here can be of help. Regards.

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  • Is Boost.Tuple compatible with C++0x variadic templates ?

    - by Thomas Petit
    Hi, I was playing around with variadic templates (gcc 4.5) and hit this problem : template <typename... Args> boost::tuple<Args...> my_make_tuple(Args... args) { return boost::tuple<Args...>(args...); } int main (void) { boost::tuple<int, char> t = my_make_tuple(8, 'c'); } GCC error message : sorry, unimplemented: cannot expand 'Arg ...' into a fixed-length argument list In function 'int my_make_tuple(Arg ...)' If I replace every occurrence of boost::tuple by std::tuple, it compiles fine. Is there a problem in boost tuple implementation ? Or is this a gcc bug ? I must stick with Boost.Tuple for now. Do you know any workaround ? Thanks.

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  • Type problem when including tuple

    - by Person
    I'm using Visual Studio 2008 with Feature Pack 1. I have a typedef like this typedef std::tr1::tuple<std::string, std::string, int> tileInfo with a function like this const tileInfo& GetTile( int x, int y ) const. In the implementation file the function has the exact same signature (with the added class name qualifier) and I am getting a redefinition: different type modifiers error. It seems to be looking for an int& instead of a tileInfo& When I mouse over the type of the function in the header, i.e. tileInfo& it brings up a little bar saying static const int tileInfo. I think this may be the problem, but I'm not sure what to do. Any help is appreciated, thanks.

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  • How to write custom data to the TCP packet header options field with Java?

    - by snarkov
    As it is defined (see: http://www.freesoft.org/CIE/Course/Section4/8.htm) the TCP header has an 'Options' field. There are a couple of options already defined (see: www.iana.org/assignments/tcp-parameters/) but I want to come up with my very own. (For experimenting/research.) How can I get Java to write (and then read) some custom data to the options field? Bonus question: if it cannot be done with Java. what kind of application can do this? (No, I don't really feel like messing with some kernel-level TCP/IP stack implementation, I want to keep it app level.) Thanks!

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  • Linux - How do i know the block map of the given file and/or the free space map of the partition.

    - by Inso Reiges
    Hello, I am on Linux and need to know either of the two things: 1) If i have a regular file on some file system on a partition under Linux is there a way to know the set of the physical blocks that this file occupies on the drive from user space? Or at least the set of the file system's clusters? 2) Is there a way to get the same information about the whole free space of the given file system? In both cases i understand that if there is any possible way to extract this info it will probably be totally unsafe and racy (anything could happen to these set of blocks between the time i see them and act on them somehow). I also really don't want an implementation that will have to know a lot about every filesystem.

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  • Which SOA architecture is most appropriate for a Java application?

    - by Robert Greiner
    I am currently working on a pretty large Java 6 application where we are looking to split some of our functionality out into a service oriented architecture. It seems that the primary SOA framework for the application space is OSGi and I have been looking into Felix and Knopplerfish but I wanted to make sure that this isn't my only option. Does it make sense to use an actual web service protocol for our application like SOAP, even though we are not building a web app? Is this even acceptable? Have any of you used an implementation of OSGi (Felix, etc.) with your desktop application? if so, how did it go? Do you know of anything better? We're all pretty new to SOA here so any help would be greatly appreciated.

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  • "Circuit breaker" for net.msmq?

    - by Alex
    Hi, The Circuit Breaker pattern, from the book Release It!, protects a service from requests while it is failing (or recovering). The net.msmq binding used with transactions give us nice retry and poison message capabilities. But I am missing the implementation of such a "Circuit breaker" pattern. A service is put under even heavier load by retries while it is already in a failure condition (like DB connectivity issues causing loads of blocked threads etc.). Anyone knows about a behavior extension or similar that explicitly closes the service host when defined failure thresholds have been exceeded? Cheers, Alex

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  • Typecasting a floating value or using the math.h floor* functions?

    - by nobody
    Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,k,t are unsigned ints, and high,low are doubles. Would this be equivalent to: t = i + (unsigned int)(((k-low)/(high-low)) * (j-i)); Is there any reason I would actually want to use math.h floor* functions over just a simple (int) typecast?

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  • How to preserve object identity across different VMs

    - by wheleph
    To be specific let me illustrate the question with Spring http-remoting example. Suppose we have such implementation of a simple interface: public SearchServiceImpl implements SearchService { public SearchJdo processSearch(SearchJdo search) { search.name = "a funky name"; return search; } } SearchJdo is itself a simple POJO. Now when we call the method from a client through http-remoting we'll get: public class HTTPClient { public static void main(final String[] arguments) { final ApplicationContext context = new ClassPathXmlApplicationContext( "spring-http-client-config.xml"); final SearchService searchService = (SearchService) context.getBean("searchService"); SearchJdo search = new SearchJdo(); search.name = "myName"; // this method actually returns the same object it gets as an argument SearchJdo search2 = searchService.processSearch(search); System.out.println(search == search2); // prints "false" } } The problem is that the search objects are different because of serializaton although from logical prospective they are the same. The question is whether there are some technique that allows to support or emulate object identity across VMs.

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  • Why implement DB connection pointer object as a reference counting pointer? (C++)

    - by DVK
    At our company one of the core C++ classes (Database connection pointer) is implemented as a reference counting pointer. To be clear, the objects are NOT DB connections themselves, but pointers to a DB connection object. The library is very old, and nobody who designed is around anymore. So far, nether I, nor any C++ experts in the company that I asked have come up with a good reason for why this particular design was chosen. Any ideas? It is introducing some problems (partially due to awful reference pointer implementation used), and I'm trying to understand if this design actually has some deep underlying reasons? The usage pattern these days seems to be that the DB connection pointer object is returned by a DB connection manager class, and it's somewhat unclear whether DB connection pointers were designed to be able to be used independently of DB connection manager.

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  • How to implement cancellable worker thread

    - by Arnold Zokas
    Hi, I'm trying to implement a cancellable worker thread using the new threading constructs in System.Threading.Tasks namespace. So far I have have come up with this implementation: public sealed class Scheduler { private CancellationTokenSource _cancellationTokenSource; public System.Threading.Tasks.Task Worker { get; private set; } public void Start() { _cancellationTokenSource = new CancellationTokenSource(); Worker = System.Threading.Tasks.Task.Factory.StartNew( () => RunTasks(_cancellationTokenSource.Token), _cancellationTokenSource.Token ); } private static void RunTasks(CancellationToken cancellationToken) { while (!cancellationToken.IsCancellationRequested) { Thread.Sleep(1000); // simulate work } } public void Stop() { try { _cancellationTokenSource.Cancel(); Worker.Wait(_cancellationTokenSource.Token); } catch (OperationCanceledException) { // OperationCanceledException is expected when a Task is cancelled. } } } When Stop() returns I expect Worker.Status to be TaskStatus.Canceled. My unit tests have shown that under certain conditions Worker.Status remains set to TaskStatus.Running. Is this a correct way to implement a cancellable worker thread?

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  • How to add response headers based on Content-type, or getting Content-type before the response is co

    - by Bozho
    I want to set the Expires header for all image/* and text/css. I'm doing this in a Filter. However: before calling chain.doFilter(..) the Content-type is not yet "realized" after calling chain.doFilter(..) the Content-type is set, but so is content-length, which forbids adding new headers (at least in Tomcat implementation) I can use the extensions of the requested resource, but since some of the css files are generated by richfaces by taking them from inside jar-files, the name of the file isn't x.css, but is /xx/yy/zz.xcss/DATB/.... So, is there a way to get the Content-type before the response is committed.

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