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• How to signal a buffer full state between posix threads

  - by mikip

  Hi I have two threads, the main thread 'A' is responsible for message handling between a number of processes. When thread A gets a buffer full message, it should inform thread B and pass a pointer to the buffer which thread B will then process. When thread B has finished it should inform thread A that it has finished. How do I go about implementing this using posix threads using C on linux. I have looked at conditional variables, is this the way to go? . I'm not experienced in multi threaded programming and would like some advice on the best avenue to take. Thanks

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• Netlink user-space and kernel-space communication

  - by sasayins

  Hi, I am learning programming in embedded systems using Linux as my main platform. And I want to create a Device Event Management Service. This service is a user-space application/daemon that will detect if a connected hardware module triggered an event. But my problem is I don't know where should I start. I read about Netlink implementation for userspace-kernelspace communication and it seems its a good idea but not sure if it is the best solution. But I read that the UDEV device manager uses Netlink to wait a "uevent" from the kernel space but it is not clear for me how to do that. I read about polling sysfs but it seems it is not a good idea to poll filesystem. What do you think the implementation that should I use in my service? Should I use netlink(hard/no clue how to) or just polling the sysfs(not sure if it works)? Thanks

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• Android: Saving custom button and spinner

  - by Jacob Huggart

  Hello All, I am new to Android programming and was handed a fairly large program that is almost complete, but needed support for switching between portrait and landscape view. I added android:configChanges="keyboardHidden|orientation" to the manifest and used onConfigurationChanged to save the view data and that works. However, there is a button that displays the date selected (when pressed a calendar to select the date comes up) and a spinner that displays the current view and is used to select a new view. Those two items are being cleared/reset and do not work at all after the screen flip. I have been attempting to use onSaveInstanceState and onRestoreInstanceState to fix that, but I cannot figure out how to get it to work. Any advice?

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• In what language was MSDOS originally written?

  - by nebukadnezzar

  In what language was MSDOS originally written in? The Wikipedia Article implies either C, QBasic or Pascal, but: C was invented to write UNIX, so I don't believe it was used to write MSDOS Pascal seems popular to teach programming, but not really popular to write Operating systems in QBasic didn't seem to be very popular for Operating Systems at the time MSDOS was developed (or was *BASIC ever very popular to write Operating Systems in it?) Except these three languages there is also Assembly, but I assume that Microsoft already switched from Assembly to a "higher" level language? Since C was originally invented for UNIX, I still wouldn't think Microsoft is using C... although the Microsoft API is written in C (I find this kind-of oxymoronic, actually). Can anyone enlighten me on this topic?

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• C/C++ - Convert 24-bit signed integer to float

  - by e-t172

  I'm programming in C++. I need to convert a 24-bit signed integer (stored in a 3-byte array) to float (normalizing to [-1.0,1.0]). The platform is MSVC++ on x86 (which means the input is little-endian). I tried this: float convert(const unsigned char* src) { int i = src[2]; i = (i << 8) | src[1]; i = (i << 8) | src[0]; const float Q = 2.0 / ((1 << 24) - 1.0); return (i + 0.5) * Q; } I'm not entirely sure, but it seems the results I'm getting from this code are incorrect. So, is my code wrong and if so, why?

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• SQL Server Agent 2005 job runs but no output

  - by alimack

  Essentially I have a job which runs in BIDS and as as a stand lone package and while it runs under the SQL Server Agent it doesn't complete properly (no error messages though). The job steps are: 1) Delete all rows from table; 2) Use For each loop to fill up table from Excel spreasheets; 3) Clean up table. I've tried this [MS page][1] (steps 1 & 2), didn't see any need to start changing from Server side security. Also SQLServerCentral.com for [this page][2], no resolution. How can I get error logging or a fix? Note I've reposted this from Server Fault as it's one of those questions that's not pure admin or programming. I have logged in as the proxy account I'm running this under, and the job runs stand alone but complains that the Excel tables are empty?

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• Using Core Data Concurrently and Reliably

  - by John Topley

  I'm building my first iOS app, which in theory should be pretty straightforward but I'm having difficulty making it sufficiently bulletproof for me to feel confident submitting it to the App Store. Briefly, the main screen has a table view, upon selecting a row it segues to another table view that displays information relevant for the selected row in a master-detail fashion. The underlying data is retrieved as JSON data from a web service once a day and then cached in a Core Data store. The data previous to that day is deleted to stop the SQLite database file from growing indefinitely. All data persistence operations are performed using Core Data, with an NSFetchedResultsController underpinning the detail table view. The problem I am seeing is that if you switch quickly between the master and detail screens several times whilst fresh data is being retrieved, parsed and saved, the app freezes or crashes completely. There seems to be some sort of race condition, maybe due to Core Data importing data in the background whilst the main thread is trying to perform a fetch, but I'm speculating. I've had trouble capturing any meaningful crash information, usually it's a SIGSEGV deep in the Core Data stack. The table below shows the actual order of events that happen when the detail table view controller is loaded: Main Thread Background Thread viewDidLoad Get JSON data (using AFNetworking) Create child NSManagedObjectContext (MOC) Parse JSON data Insert managed objects in child MOC Save child MOC Post import completion notification Receive import completion notification Save parent MOC Perform fetch and reload table view Delete old managed objects in child MOC Save child MOC Post deletion completion notification Receive deletion completion notification Save parent MOC Once the AFNetworking completion block is triggered when the JSON data has arrived, a nested NSManagedObjectContext is created and passed to an "importer" object that parses the JSON data and saves the objects to the Core Data store. The importer executes using the new performBlock method introduced in iOS 5: NSManagedObjectContext *child = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]; [child setParentContext:self.managedObjectContext]; [child performBlock:^{ // Create importer instance, passing it the child MOC... }]; The importer object observes its own MOC's NSManagedObjectContextDidSaveNotification and then posts its own notification which is observed by the detail table view controller. When this notification is posted the table view controller performs a save on its own (parent) MOC. I use the same basic pattern with a "deleter" object for deleting the old data after the new data for the day has been imported. This occurs asynchronously after the new data has been fetched by the fetched results controller and the detail table view has been reloaded. One thing I am not doing is observing any merge notifications or locking any of the managed object contexts or the persistent store coordinator. Is this something I should be doing? I'm a bit unsure how to architect this all correctly so would appreciate any advice.

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• A Question About the Expressive Power of Higher-Order Logical Reasoning Formalisms.

  - by Bubba88

  Hi! I do not really know if this is scientifically proven, but I've read in a book (It was a relatively modern AI book by Peter Norvig) that secon-order logical programming could be more expressive than existing first-order languages. The question is: Is it statistically/symbolically proven that higher-order predicate logics exceed first-order predicates in their expressive power? Or they just bring the modularity/convenience/maintainability to your knowledge bases? Additionally: If there is some kind of firm direction in which I could go seeking more expressive power than I have (I mean exactly the descriptive potential of the symbols I write in given semantics/syntax) - then I would be glad to hear just almost everything :) Thank you.

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• C# Proxy, what is the best way to do this?

  - by Kin

  I'm writing a proxy using .NET and C#. It has a couple of functions that it needs to fulfill. I haven't done much Socket programming, and I am not sure the best way to go about it. Should I use Synchronous Sockets, Asynchronous sockets? Please help! It must... Accept Connections from the client on two different ports, and be able to receive data on both ports at the same time. When a connection is made on a port, it must immediately connect to the server, and start sending data as it receives it from the client to the server. Packets must be forwarded in the order they are received, exactly as they were received. It needs to be as low latency as possible. I don't need the ability for multiple clients to use the proxy, but it would be a nice feature if its easy to implement.

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• Is problem solving of puzzles/logic tests a skill that can be developed with practise or only someth

  - by dotnetdev

  Programming is essentially problem solving/using a lot of logic. With solving puzzles (like the ones recruiters like MS etc ask), is this a skill that can be developed with practise or is it a skill that only someone who is gifted has (I assume the former as many people can pass these tests)? Even so, I keep thinking it is a special skill for someone gifted, not for someone with a lot of practise. I guess that with practise you are perhaps more open-minded and start to think out of the box more (solving technical problems in development may also foster this mindset perhaps). Thanks

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• Getting SQL Server Compact 4.0 Tools CTP2

  - by sinni800

  Hello. I'm currently trying to install the "new" Microsoft WebMatrix Beta 2 (a web programming IDE). I was trying to use Web Platform Installer for this. But it 404's on the SQL Compact 4.0 CPT2 and it's tools. I was able to get the runtime from the Microsoft downloads page but the tools I am not able to find. I can not install WebMatrix because the tools are a prerequisite. Does anybody know where to get them from now?

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• CMS common Architecture

  - by Shalan

  Hi there, I know this is a weird question to ask, but I would like to know if there is any documentation/blog-article out there that explains the architecture of a Website content management system? More particularly, I am interested to learn more about how "widgets" are implemented. I can't remember which system it was that I've seen tis one, but in the "Page Layout view" it had the ability to allow the end user to select a widget (thumbnail gallery, contact form, etc) from a list, and drag and drop it onto custom areas of the page. I know that this is not directly a programming question, but please could I seek advice/feedback on this. Thanks!

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• Python, how to tell if screen is running.

  - by Joe Spoon

  Hello, I am very new to programming and am trying to run a python code to see if the screen program is running and if it is then to not run the rest of the code. This is what I have and it's not working. !/usr/bin/python import os var1 = os.system ('screen -r /root/screenlog/screen.log') fd = open("/root/screenlog/screen.log") content = fd.readline() while content: if content == "There is no screen to be resumed.": os.system ('/etc/init.d/tunnel.sh') print "The tunnel is now active." else: print "The tunnel is running." fd.close() I know there are probably several things here that don't need to be and quite a few that I'm missing. I will be running this program in cron. Thanks for any help.

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• Easiest, free way to start with Flex?

  - by Jon

  I'm interested in getting started with Flex, as I've wanted to work with flash for quite awhile but have never liked the designer-oriented way of programming. I've heard flex can be used for free, and is programmer friendly, but I'm having some issues... I can't find any good sites with flex resources. I'm used to PHP, so maybe I'm spoiled with a full manual, comments and tutorials, but I can't even find a decent tutorial site. So, what are some good flex starts to get started, and what's a good, free IDE to program with?

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• How do I safely Debug.Assert in ASP.NET?

  - by MatthewMartin

  Asserts can't be caught. This is good because some errors I don't want to be wrapped in try/catch, at least not on the development server. But Asserts seem awefully dangerous. If they get onto production, it can hang the ASP.NET server with a msgbox. //Don't want this on prod even if debug=true is in the web.config #if DEBUG //A future client programmer can wrap this in a try{}catch{} if (!EverythingIsOkay) throw new InvalidOperationException("Dagnabbit, programming error"); //This stops the but has less information that an // Exception and hangs the server if this accidentally // runs on production System.Diagnostics.Debug.Assert(!EverythingIsOkay); #endif Is there better way to communicate an violation of a inviolable condition to a developer without risking hanging IIS? UPDATE: After reading the first replies, I guess the answer hinges on a foolproof way to detect when code is running in a development environment and when it is on a production server, or figuring out how to throw an exception that can't be caught and ignored.

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• Are there built-in issue tracking and task management in IDEs that integrate into SourceForge, Googl

  - by Kai Sellgren

  Hi, This question may not be exactly programming related, but this is about development. I have been trying to find IDEs that support JIRA/Bugzilla so that I could simply integrate the IDE with SourceForge. I do not like to refresh my browser to see issues, bug reports, security problems, etc. I would like to send issues, resolve issues, right from the IDE. I am currently developing with NetBeans, but I see no ways of integrating into any of the services provided by SourceForge. Am I missing something?

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• How to replace values in multi-valued ESE column?

  - by Soonts

  I have a multi-valued short ASCII text column in one of the tables in my ESE database, that holds the person's phone numbers. I have the new set of values, and I'd like to wipe the old values completely, and only use the new values. The JET_bitSetRevertToDefaultValue bit doesn't seem to work. While the MSDN documentation says "It causes the column to return the default column value on subsequent retrieve column operations. All existing column values are removed.", I found that it does nothing (no return value is returned). Or, is there an easy way to find out how many values does the column contain (this could be zero, e.g. when I'm doing an insertion, not update)? If it was, I could just run a loop from 'nValues' to 1, erasing the value by setting it to the null while providing the itagSequence value, to achieve what I want. I'm programming C#, and using the latest version of ManagedEsent library. Thanks in advance!

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• Appending Integer array elements in Java

  - by Neville

  I have an array, say int a[]={2,0,1,0,1,1,0,2,1,1,1,0,1,0,1}; I need to append each of the 5 neighboring elements and assign them to a new array b with length=(a.length/5); and i want to append the 5 neighboring elements so that I have: int b[]={20101,10211,10101}; I need to do this for various length arrays, in most cases with length of a being greater than 15. Any help would be greatly appreciated, I'm programming in Java. Thanks in advance.

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• Best way to return a user-generated file, AJAX or Forms?

  - by Bill Zimmerman

  Hi, I'm new to web programming, so I need some help. I am writing a custom file-creation app for my site. A user visits the page, clicks on some various options and toggles some checkboxes, and the presses a 'download now' link. I have a PHP backend which will be processing the submission, and generating a PDF file. After the user presses the download link, I want the download to start like it would for any static link. My question is: What is the best way to do this? From my limited understanding, I have a choice between using AJAX or somehow using forms to submit the data. What are the advantages/disadvantages of each? Does anyone have any good links to examples? Thanks

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• Automatic setting of Local Time zone w/DST

  - by Frode Roed

  I can derive latitude and longitude and UTC time from GPS NMEA sentences. Now, how can I automaticly adjust the Windows local time zone on my PC (2003 Server OS), based on this? Also, Is there an easy way of distributing this to clients based on code or apps software? Preferred programming environment is .NET, C# & Visual Studio. I use a GPS Time server (GPS clock with antenna) today, but this could not support other than UTC. I want to set computers in my TCP/UDP network to correct time zone w/DST based on coordinates derived from GPS, so manually setting of all is not required.

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• How to join two wav file using python??

  - by kaushik

  I am using python programming language,I want to join to wav file one at the end of other wav file? I have a Question in the forum which suggest how to merge two wav file i.e add the contents of one wav file at certain offset,but i want to join two wav file at the end of each other... And also i had a prob playing the my own wav file,using winsound module..I was able to play the sound but using the time.sleep for certain time before playin any windows sound,disadvantage wit this is if i wanted to play a sound longer thn time.sleep(N),N sec also,the windows sound wil jst overlap after N sec play the winsound nd stop.. Can anyone help??please kindly suggest to how to solve these prob... Thanks in advance

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• When to databind data-bound controls?

  - by sanjuro

  Hi, i have little dilemma, i often use data-bound controls such as Gridview in conjunction with ObjectDataSource. But i have two possible options when can i bind data to Gridview. The first is that i set datasourceid of gridview in aspx file and databind occurs in a moment before PreRender event occurs or i can set datasource in Page_Load event and databinding occurs immediately, something like this: protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { testGridView.DataSource = testObjectDataSource.Select(); testGridView.DataBind(); } } I think that in second approach i have more control above databinding. But how it is in real programming life? Which of the above two options is commonly used? Or is there some third option how can i bind data to data-bound control? Thanks for your opinions from real-life experiences.

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• How best to debug Delphi using the IDE and/or FOSS?

  - by LeonixSolutions

  I am currently using Delphi 7 and unsure whether to upgrade. I see the following means of debugging and wonder if there are others or which FOSS tools a small company can use (we don't do much Windows programming). 1 Debug in the IDE, by setting breakpoints, using watches, etc 2 Debug in the IDE, by using the Event Log I got some good info from this page and tweaked it to add timestamps and indent/outdent on procedure call/return, so that I can see nested calls more quickly. Does anyone know of anything better ? 3 Using a profiler 4 Any others? Such as MadExcept, etc?

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• Access Rails under /app/, not /app/public/

  - by blinry

  I'm trying to deploy Rails 2.1.2 with Apache 2.2.10 and FastCGI (yeah, bad, ancient, ugly, I know). And I know it's no programming question, but please bear with me. My application can be accessed via example.com/app/public/, but I want to access it via example.com/app/. In my .htaccess-File (in the app/-directory!) I have: RewriteEngine On RewriteBase /app/ RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.*)$ public/dispatch.fcgi [QSA,L] How can I forward each request going to app/ to app/public/? Every time I try this (like, with RewriteRule ^.*$ public/$1 [QSA]) I get a routing error: No route matches "/app/" with {:method=>:get} Help?

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• Languages/Technologies advice

  - by BL

  Hi all, a bit of advice required here :). I recently graduated(Computer Science), and need to decide a path to take programming/technology wise. I have knowledge of Java, C, SQL most of it is university level stuff. I work daily with PHP/SQL building web apps. Which language / technology would you advise me to learn. I am very interested in Database management, GIS etc. Web dev is also very interesting to me. It is all a bit confusing since i would like to learn something that will have a value at least in the near future. I would like to have some ideas on which language/technology is god choice in order to be marketable.

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