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  • Dynamics of the using keyword

    - by AngryHacker
    Consider the following code: // module level declaration Socket _client; void ProcessSocket() { _client = GetSocketFromSomewhere(); using (_client) { DoStuff(); // receive and send data Close(); } } void Close() { _client.Close(); _client = null; } Given that that the code calls the Close() method, which closes the _client socket and sets it to null, while still inside the `using' block, what exactly happens behind the scenes? Does the socket really get closed? Are there side effects? P.S. This is using C# 3.0 on the .NET MicroFramework, but I suppose the c#, the language, should function identically. The reason i am asking is that occasionally, very rarely, I run out of sockets (which is a very precious resource on a .NET MF devices).

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  • Can immutable be a memory hog?

    - by ciscoheat
    Let's say we have a memory-intensive class like an Image, with chainable methods like Resize() and ConvertTo(). If this class is immutable, won't it take a huge amount of memory when I start doing things like i.Resize(500, 800).Rotate(90).ConvertTo(Gif), compared to a mutable one which modifies itself? How to handle a situation like this in a functional language?

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  • Able to ping but cannot browse after several hours running of my python program

    - by Shane
    It's a GUI program I wrote in python checking website/server status running on my XP SP3, multi threads are used to check different site/server. After several hours running, the program starts to get urlopen error timed out all the time, and this always happens right after a POST request from a server(not a certain one, might be A or B or C), and it's also not the first POST request causing the problem, normally after several hours running and it happens to make a POST request at an unknown moment, all you get from then on is urlopen error timed out. I'm still able to ping but cannot browse any site, once the program closed everything's fine. It's definitely the program causing this problem, well I just don't know how to debug/check what the problem is, also don't know if it's from OS side or my program wasting too many resources/connections(are you still able to ping when too many connections used?), would anybody please help me out?

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  • TcpListener.Start() does not open the port

    - by SoMoS
    Hello, I have a class that inherits from the TcpListener, this class Shadows the Start method just to call the base Start() and the base BeginAcceptTcpClient(). From time to time the method is called but the port is not opened (netstat does not show the port open). The class looks like this Public Class ExtendedTcpListener Inherits System.Net.Sockets.TcpListener Public Shadows Sub Start() SyncLock (m_stopLock) MyBase.Start() MyBase.BeginAcceptTcpClient(AddressOf Me.CompleteAcceptTcpClient, Me) My.Application.Log.WriteEntry("Extended Tcp Listener started ...", TraceEventType.Verbose) End SyncLock End Sub Any idea on what's happening or how to debug the issue? As the Start() is called without exception I expected to find the port always opened (the log is always written). Extra information: when the Start method works fine it works each time until app is restarted. When the Start method does not work it won't work again until the app is restarted.

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  • How to get Acknowlegement in TCP communication in Java

    - by Sunil Kumar Sahoo
    I have written a socket program in Java. Both server and client can sent/receive data to each other. But I found that if client sends data to server using TCP then internally TCP sends acknowledgement to the client once the data is received by the server. I want to detect or handle that acknowledgement. How can I read or write data in TCP so that I can handle TCP acknowledgement. Thanks Sunil Kumar Sahoo

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  • Solaris: Programmatic interface to ifconfig?

    - by David Citron
    I'm looking for a programmatic interface to the Solaris ifconfig(1M) command. Apparently Linux has the getifaddrs(3) command, but as far as I can tell this has not been ported to Solaris. Short of attempting to use the code at the link above, is there any way to determine ifconfig(1M)-type data (network interface presence, state, etc.) without forking the system command and parsing the output?

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  • How hard is FizzBuzz? [closed]

    - by Josh K
    After reading various blog entries I took it upon myself to code a FizzBuzz program in PHP. class FizzBuzz { function __construct() { } function go() { for($i = 1; $i < 101; $i++) { if($i % 3 == 0 and $i % 5 == 0) { echo("FizzBuzz\n"); continue; } else if($i % 3 == 0) { echo("Fizz\n"); continue; } else if($i % 5 == 0) { echo("Buzz\n"); continue; } else { echo($i."\n"); } } } } $FB = new FizzBuzz(); $FB->go(); Created the FizzBuzz object just because I could, I complete this in under five minutes. Is it really that hard to do?

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  • McAfee Virus Scan and Oracle RAC

    - by Lee Gathercole
    Hi, We're experiencing a strange problem with Oracle RAC and McAfee anti-virus. As part of the installation of the Oracle RAC we disable anti virus as directed. We have had our RAC running fine, but when we came to re-enable the AV and reboot we got the BSOD. Abnormal Program Termination (BugCheck, STOP: 0x00000035 (0x8E984678, 0x00000000, 0x00000000, 0x00000000 NO_MORE_IRP_STACK_LOCATIONS Following the standard process of raising this problem with Microsoft they identify the problem and also a fix. Microsoft talk about too many file filter drivers being present and pushing the DFS upper limit beyond the default size. Upping this value, as per msdn, has no impact. We're able to recover from this BSOD by disabling AV. We don't have the problem if we run the AV service manually whilst the system is up. However, if we make the service automatic we fail to boot. Tech Details 2 Node Oracle 10g Cluster 2 * Windows 2003 SP2, 16GB RAM, Quad Core 3ghz Processor SAN attached storage McAfee VirusScan Enterprise 8.5.0i, Scan Engine (5300.2777), DAT Version (5536.0000) Thanks Lee

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  • JVM/CLR Source-compatible Language Options

    - by Nathan Voxland
    I have an open source Java database migration tool (http://www.liquibase.org) which I am considering porting to .Net. The majority of the tool (at least from a complexity side) is around logic like "if you are adding a primary key and the database is Oracle use this SQL. If database is MySQL use this SQL. If the primary key is named and the database is Postgres use this SQL". I could fork the Java codebase and covert it (manually and/or automatically), but as updates and bug fixes to the above logic come in I do not want to have to apply it to both versions. What I would like to do is move all that logic into a form that can be compiled and used by both Java and .Net versions naively. The code I am looking to convert does not contain any advanced library usage (JDBC, System.out, etc) that would vary significantly from Java to .Net, so I don't think that will be an issue (at worst it can be designed around). So what I am looking for is: A language in which I can code common parts of my app in and compile it into classes usable by the "standard" languages on the target platform Does not add any runtime requirements to the system Nothing so strange that it scares away potential contributors I know Python and Ruby both have implementations on for the JVM and CLR. How well do they fit my requirements? Has anyone been successful (or unsuccesful) using this technique for cross-platform applications? Are there any gotcha's I need to worry about?

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  • Apache HttpClient CoreConnectionPNames.CONNECTION_TIMEOUT does nothing ?

    - by Maxim Veksler
    Hi, I'm testing some result from HttpClient that looks irrational. It seems that setting CoreConnectionPNames.CONNECTION_TIMEOUT = 1 has no effect because send request to different host return successfully with connect timeout 1 which IMHO can't be the case (1ms to setup TCP handshake???) Am I misunderstood something or is something very strange going on here? The httpclient version I'm using as can be seen in this pom.xml is <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.0.1</version> <type>jar</type> </dependency> Here is the code: import java.io.IOException; import java.util.Random; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.params.CoreConnectionPNames; import org.apache.http.util.EntityUtils; import org.apache.log4j.Logger; public class TestNodeAliveness { private static Logger log = Logger.getLogger(TestNodeAliveness.class); public static boolean nodeBIT(String elasticIP) throws ClientProtocolException, IOException { try { HttpClient client = new DefaultHttpClient(); // The time it takes to open TCP connection. client.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 1); // Timeout when server does not send data. client.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, 5000); // Some tuning that is not required for bit tests. client.getParams().setParameter(CoreConnectionPNames.STALE_CONNECTION_CHECK, false); client.getParams().setParameter(CoreConnectionPNames.TCP_NODELAY, true); HttpUriRequest request = new HttpGet("http://" + elasticIP); HttpResponse response = client.execute(request); HttpEntity entity = response.getEntity(); if(entity == null) { return false; } else { System.out.println(EntityUtils.toString(entity)); } // Close just in case. request.abort(); } catch (Throwable e) { log.warn("BIT Test failed for " + elasticIP); e.printStackTrace(); return false; } return true; } public static void main(String[] args) throws ClientProtocolException, IOException { nodeBIT("google.com?cant_cache_this=" + (new Random()).nextInt()); } } Thank you.

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  • How should I go about implementing a points-to analysis in Maude?

    - by reprogrammer
    I'm going to implement a points-to analysis algorithm. I'd like to implement this analysis mainly based on the algorithm by Whaley and Lam. Whaley and Lam use a BDD based implementation of Datalog to represent and compute the points-to analysis relations. The following lists some of the relations that are used in a typical points-to analysis. Note that D(w, z) :- A(w, x),B(x, y), C(y, z) means D(w, z) is true if A(w, x), B(x, y), and C(y, z) are all true. BDD is the data structure used to represent these relations. Relations input vP0 (variable : V, heap : H) input store (base : V, field : F, source : V) input load (base : V, field : F, dest : V) input assign (dest : V, source : V) output vP (variable : V, heap : H) output hP (base : H, field : F, target : H) Rules vP(v, h) :- vP0(v, h) vP(v1, h) :- assign(v1, v2), vP(v2, h) hP(h1, f,h2) :- store(v1, f, v2), vP(v1, h1), vP(v2, h2) vP(v2, h2) :- load(v1, f, v2), vP(v1, h1), hP(h1, f, h2) I need to understand if Maude is a good environment for implementing points-to analysis. I noticed that Maude uses a BDD library called BuDDy. But, it looks like that Maude uses BDDs for a different purpose, i.e. unification. So, I thought I might be able to use Maude instead of a Datalog engine to compute the relations of my points-to analysis. I assume Maude propagates independent information concurrently. And this concurrency could potentially make my points-to analysis faster than sequential processing of rules. But, I don't know the best way to represent my relations in Maude. Should I implement BDD in Maude myself, or Maude's internal unification based on BDD has the same effect?

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  • ByteStrings in Haskell

    - by Jon
    So i am trying to write a program that can read in a java class file as bytecode. For this i am using Data.Binary and Data.ByteStream. The problem i am having is because im pretty new to Haskell i am having trouble actually using these tools. module Main where import Data.Binary.Get import Data.Word import qualified Data.ByteString.Lazy as S getBinary :: Get Word8 getBinary = do a <- getWord8 return (a) main :: IO () main = do contents <- S.getContents print (getBinary contents) This is what i have come up with so far and i fear that its not really even on the right track. Although i know this question is very general i would appreciate some help with what i should be doing with the reading.

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  • Javascript comma operator

    - by Claudiu
    When combining assignment with comma (something that you shouldn't do, probably), how does javascript determine which value is assigned? Consider these two snippets: function nl(x) { document.write(x + "<br>"); } var i = 0; nl(i+=1, i+=1, i+=1, i+=1); nl(i); And: function nl(x) { document.write(x + "<br>"); } var i = 0; nl((i+=1, i+=1, i+=1, i+=1)); nl(i); The first outputs 1 4 while the second outputs 4 4 What are the parentheses doing here?

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  • Best code structure for arcade games

    - by user280454
    Hi, I've developed a few arcade games so far and have the following structure in almost all of them: I have 1 file which contains a class called kernel with the following functions: init() welcome_screen() menu_screen() help_Screen() play_game() end_screen() And another file, called Game, which basically calls all these functions and controls the flow of the game. Also, I have classes for different characters, whenever required. Is this a good code structure, or should I try having different files(classes) for different functions like welcome screen, playing, help screen, etc? As in, instead of including all the code for these things in 1 file, should I be having different classes for each one of them? The only problem I think it might cause is that I would need certain variables like score, characters, etc which are common to all of them, that's why I have all these functions in a Kernel class so that all these functions can use these variables.

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  • Linux Kernel - traverse to buffer heads

    - by CodeRanger
    In the Linux kernel, is there a way to traverse down to the buffer_heads from within a module? I can see how to get to struct bio (task_struct macro: current-bio). But how can I get to the buffer heads? The buffer_head struct holds some information I'd like to obtain at any point regarding physical block numbers.

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  • Do Scala and Erlang use green threads?

    - by CHAPa
    I've been reading a lot about how Scala and Erlang does lightweight threads and their concurrency model (actors). However, I have my doubts. Do Scala and Erlang use an approach similar to the old thread model used by Java (green threads) ? For example, suppose that there is a machine with 2 cores, so the Scala/Erlang environment will fork one thread per processor? The other threads will be scheduled by user-space (Scala VM / Erlang VM ) environment. Is this correct? Under the hood, how does this really work?

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  • How do I evaluate my skillset against the current market to see what needs improvement and where my

    - by baijajusav
    First of all, this question may be out of bounds for this site. If so, remove it. I say this because this site seems to be a place for more concrete questions that are not so relative in nature. And before I begin, for those of you whom just prefer a question and not this sort of dialog, here is my question: How can I assess my current skills as a programmer and decide where and what areas to improve upon? That said, here's what I'm asking/talking about, in essence. The market is always in constant flux. As programmers we're always having to learn new things, update our skills, push ourselves into that next project. There's not a very good litmus test that I know of for us to get an idea of where we stand as programmers. I came across this blog post by Jeff Atwood talking about why can't programmers code. Instinctively (and as the post goes on to state) I rushed through the program in about 4 minutes (most of that time was b/c I was hand writing it out. Still, this doesn't really answer the question of where do my skills need to be to succeed in today's world. I real blogs, listen to podcasts, try to keep up on the latest things coming out. It has only been in the past couple of months that I made a decision to pick a focus area for my learning as I can't learn everything and trying to do so is to spread myself too thin. I chose ASP.NET MVC & C#. I plan to stick with Microsoft technologies, not out of some sense of loyalty or stubbornness, but rather because they seem to stream together and have a unifying connection between them. With Windows Phone 7 coming out, it seems that now is the obvious time to pick up WPF and Silverlight as well. Still, if you asked me to code something apart from intellisense and the internet, I probably couldn't get the syntax right. I don't have libraries memorized or know precisely where the classes I use exist within the .Net framework, namely because I haven't had to pull that knowledge out of the air. In a way, I suppose Visual Studio has insulated me, which isn't a good thing, but, at the same time, I've still been able to be productive. I'm working on my own side project to try and help my learning. In doing so, I'm trying to make use of best practices and 3rd party frameworks where I can. I'm using automapper and EF 1.0. I know everyone in the .net community seems to cry foul at the sound of EF 1.0, but I can't say why because I've never used it. There's no lazy loading and that has proven rather annoying; however, aside from that, I haven't had that much of an issue. Granted this is probably because I'm not writing tests as I go (which I'm not doing because I don't know how to test EF in tests and don't really have a clue how to write tests for ASP.NET MVC 1.0). I'm also using a custom membership provider; granted, it's a barebone implementation, but I'm using it still. My thinking in all of this is, while I am neglecting a great many important technologies that are in the mainstream, I'll have a working project in the end. I can come back and add those things after I finish. Doing it all now and at once seems like too much. I know how I work and I don't think I'd ever get it done that way. I've elected to make this a community wiki as I think this question might fight better there. If a moderator disagrees with that choice or the decision to post this here, the just delete the question. I'm not trying to make undue work for anyone. I'm just a programmer trying to assess my where his skills are now and where I should be improving.

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  • Sparse constrained linear least-squares solver

    - by Jacob
    This great SO answer points to a good sparse solver, but I've got constraints on x (for Ax = b) such that each element in x is >=0 an <=N. The first thing which comes to mind is an QP solver for large sparse matrices. Also, A is huge (around 2e6x2e6) but very sparse with <=4 elements per row. Any ideas/recommendations? I'm looking for something like MATLAB's lsqlin but with huge sparse matrices.

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  • How to loop through a boost::mpl::list?

    - by Kyle
    This is as far as I've gotten, #include <boost/mpl/list.hpp> #include <algorithm> namespace mpl = boost::mpl; class RunAround {}; class HopUpAndDown {}; class Sleep {}; template<typename Instructions> int doThis(); template<> int doThis<RunAround>() { /* run run run.. */ return 3; } template<> int doThis<HopUpAndDown>() { /* hop hop hop.. */ return 2; } template<> int doThis<Sleep>() { /* zzz.. */ return -2; } int main() { typedef mpl::list<RunAround, HopUpAndDown, Sleep> acts; // std::for_each(mpl::begin<acts>::type, mpl::end<acts>::type, doThis<????>); return 0; }; How do I complete this? (I don't know if I should be using std::for_each, just a guess based on another answer here)

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