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  • What do you need to know to be a world-class master software developer? [closed]

    - by glitch
    I wanted to bring up this question to you folks and see what you think, hopefully advise me on the matter: let's say you had 30 years of learning and practicing software development in front of you, how would you dedicate your time so that you'd get the biggest bang for your buck. What would you both learn and work on to be a world-class software developer that would make a large impact on the industry and leave behind a legacy? I think that most great developers end up being both broad generalists and specialists in one-two areas of interest. I'm thinking Bill Joy, John Carmack, Linus Torvalds, K&R and so on. I'm thinking that perhaps one approach would be to break things down by categories and establish a base minimum of "software development" greatness. I'm thinking: Operating Systems: completely internalize the core concepts of OS, perhaps gain a lot of familiarity with an OSS one such as Linux. Anything from memory management to device drivers has to be complete second nature. Programming Languages: this is one of those topics that imho has to be fully grokked even if it might take many years. I don't think there's quite anything like going through the process of developing your own compiler, understanding language design trade-offs and so on. Programming Language Pragmatics is one of my favorite books actually, I think you want to have that internalized back to back, and that's just the start. You could go significantly deeper, but I think it's time well spent, because it's such a crucial building block. As a subset of that, you want to really understand the different programming paradigms out there. Imperative, declarative, logic, functional and so on. Anything from assembly to LISP should be at the very least comfortable to write in. Contexts: I believe one should have experience working in different contexts to truly be able to appreciate the trade-offs that are being made every day. Embedded, web development, mobile development, UX development, distributed, cloud computing and so on. Hardware: I'm somewhat conflicted about this one. I think you want some understanding of computer architecture at a low level, but I feel like the concepts that will truly matter will be slightly higher level, such as CPU caching / memory hierarchy, ILP, and so on. Networking: we live in a completely network-dependent era. Having a good understanding of the OSI model, knowing how the Web works, how HTTP works and so on is pretty much a pre-requisite these days. Distributed systems: once again, everything's distributed these days, it's getting progressively harder to ignore this reality. Slightly related, perhaps add solid understanding of how browsers work to that, since the world seems to be moving so much to interfacing with everything through a browser. Tools: Have a really broad toolset that you're familiar with, one that continuously expands throughout the years. Communication: I think being a great writer, effective communicator and a phenomenal team player is pretty much a prerequisite for a lot of a software developer's greatness. It can't be overstated. Software engineering: understanding the process of building software, team dynamics, the requirements of the business-side, all the pitfalls. You want to deeply understand where what you're writing fits from the market perspective. The better you understand all of this, the more of your work will actually see the daylight. This is really just a starting list, I'm confident that there's a ton of other material that you need to master. As I mentioned, you most likely end up specializing in a bunch of these areas as you go along, but I was trying to come up with a baseline. Any thoughts, suggestions and words of wisdom from the grizzled veterans out there who would like to share their thoughts and experiences with this? I'd really love to know what you think!

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  • A simple augmented reality application in C#

    - by Ian
    Hi All, I would like to start a personal project that will give me a lot of new concept to learn and understand. After some thought, I figured that an Augmented Reality related project will be the most beneficial for me because of the following reasons: I haven't tried interfacing a program with a live video/camera feed I haven't done any "image processing" project I haven't done any "graphics rendering" ever With that said, you can assume that I will totally suck at AR. So I'm here to ask for some advice regarding the best way to go through this. st milestone project that I am thinking of is to take a cheap webcam and read some Data Matrix using C#. nd milestone project will render some text-overlay on the feed when presented with a certain Data Matrix. rd milestone project will actually render some 3D shapes. I've searched all-around and found some nice yet advanced materials for AR: http://sites.google.com/site/augmentedrealitytestingsite/ http://soldeveloper.com/ http://www.mperfect.net/wpfAugReal/ So I came here to ask the following: Do you think my milestone is reasonable given my "deficiencies"? In order to start Milestone 1, can you give some materials that I can study? I prefer online materials. Thanks!

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  • C# .Net Serial DataReceived Event response too slow for high-rate data.

    - by Matthew
    Hi, I have set up a SerialDataReceivedEventHandler, with a forms based program in VS2008 express. My serial port is set up as follows: 115200, 8N1 Dtr and Rts enabled ReceivedBytesThreshold = 1 I have a device I am interfacing with over a BlueTooth, USB to Serial. Hyper terminal receives the data just fine at any data rate. The data is sent regularly in 22 byte long packets. This device has an adjustable rate at which data is sent. At low data rates, 10-20Hz, the code below works great, no problems. However, when I increase the data rate past 25Hz, there starts to recieve mulitple packets on one call. What I mean by this is that there should be a event trigger for every incoming packet. With higher output rates, I have tested the buffer size (BytesToRead command) immediatly when the event is called and there are multiple packets in the buffer then. I think that the event fires slowly and by the time it reaches the code, more packes have hit the buffer. One test I do is see how many time the event is trigger per second. At 10Hz, I get 10 event triggers, awesome. At 100Hz, I get something like 40 event triggers, not good. My goal for data rate is 100HZ is acceptable, 200Hz preferred, and 300Hz optimum. This should work because even at 300Hz, that is only 52800bps, less than half of the set 115200 baud rate. Anything I am over looking? public Form1() { InitializeComponent(); serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived); } private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e) { this.Invoke(new EventHandler(Display_Results)); } private void Display_Results(object s, EventArgs e) { serialPort1.Read(IMU, 0, serial_Port1.BytesToRead); }

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  • Looking for Hardware that will easily interface with my .NET code.

    - by SkippyFire
    I'm a .NET C# developer looking to do some hardware interfacing/programming. I just want something super simple to mess around with. I have done one of those basic stamp projects, but I want something with less electrical work. A self-contained piece of hardware would be fine. I'm not really looking to do embedded programming... but that would actually be pretty cool if something was capable of running .net code. I'm looking for something that would be easy to connect, hopefully via USB. Serial ports seems to be more hit or miss nowadays with laptops and netbooks. Something I can easily send data to, like a mini LCD, or series of LED's. Better yet would be something that provides feedback, like a temperature sensor. The best would be something more featured that I could talk to. I would be able to send data to it, and it would send back responses. Maybe something like a servo that could report it's position? Or maybe something that I could set parameters on? Any ideas? Thanks in advance!

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  • Why do Unicode characters show up properly in database, but as ? when printed in Java via Hibernate?

    - by lupefiasco
    I'm writing a webapp, and interfacing with MySQL using Hibernate 3.5. Using "?????? ?????????" as my test string, I can input the string and see that it is properly persisted into the database. However, when I later pull the value out of the database and print to the console as a String, I see "?????? ?????????". If I use new OutputStreamWriter(System.out,"UTF-8"); then I get "„Éá„Çp„ÇØ„Éà„ÉÉ„Éó ·Éò·Éú·Éí·Éö·Éò·É°·É£·É†·Éò"". Why don't I see the original string? These are my hibernate.cfg.xml settings: <property name="hibernate.connection.useUnicode"> true </property> <property name="hibernate.connection.characterEncoding"> UTF-8 </property> <property name="hibernate.connection.charSet"> UTF-8 </property> and this is my database connection string: hibernate.connection.url = jdbc:mysql://localhost/mydatabase?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=UTF-8

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  • Organizing code, logical layout of segmented files

    - by David H
    I have known enough about programming to get me in trouble for about 10 years now. I have no formal education, though I've read many books on the subject for various languages. The language I am primarily focused on now would be php, atleast for the scale of things I am doing now. I have used some OOP classes for a while, but never took the dive into understanding principals behind the scenes. I am still not at the level I would like to be expression-wise...however my recent reading into a book titled The OOP Thought Process has me wanting to advance my programming skills. With motivation from the new concepts, I have started with a new project that I've coded some re-usable classes that deal with user auth, user profiles, database interfacing, and some other stuff I use regularly on most projects. Now having split my typical garbled spaghetti bowl mess of code into somewhat organized files, I've come into some problems when it comes to making sure files are all included when they need to be, and how to logically divide the scripts up into classes, aswell as how segmented I should be making each class. I guess I have rambled on enough about much of nothing, but what I am really asking for is advise from people, or suggested reading that focuses not on specific functions and formats of code, but the logical layout of projects that are larger than just a hobby project. I want to learn how to do things proper, and while I am still learning in some areas, this is something that I have no clue about other than just being creative, and trial/error. Mostly error. Thanks for any replies. This place is great.

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  • Thread implemented as a Singleton

    - by rocknroll
    Hi all, I have a commercial application made with C,C++/Qt on Linux platform. The app collects data from different sensors and displays them on GUI. Each of the protocol for interfacing with sensors is implemented using singleton pattern and threads from Qt QThreads class. All the protocols except one work fine. Each protocol's run function for thread has following structure: void <ProtocolClassName>::run() { while(!mStop) //check whether screen is closed or not { mutex.lock() while(!waitcondition.wait(&mutex,5)) { if(mStop) return; } //Code for receiving and processing incoming data mutex.unlock(); } //end while } Hierarchy of GUI. 1.Login screen. 2. Screen of action. When a user logs in from login screen, we enter the action screen where all data is displayed and all the thread's for different sensors start. They wait on mStop variable in idle time and when data arrives they jump to receiving and processing data. Incoming data for the problem protocol is 117 bytes. In the main GUI threads there are timers which when timeout, grab the running instance of protocol using <ProtocolName>::instance() function Check the update variable of singleton class if its true and display the data. When the data display is done they reset the update variable in singleton class to false. The problematic protocol has the update time of 1 sec, which is also the frame rate of protocol. When I comment out the display function it runs fine. But when display is activated the application hangs consistently after 6-7 hours. I have asked this question on many forums but haven't received any worthwhile suggestions. I Hope that here I will get some help. Also, I have read a lot of literature on Singleton, multithreading, and found that people always discourage the use of singletons especially in C++. But in my application I can think of no other design for implementation. Thanks in advance A Hapless programmer

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  • Is it valid to use unsafe struct * as an opaque type instead of IntPtr in .NET Platform Invoke?

    - by David Jeske
    .NET Platform Invoke advocates declaring pointer types as IntPtr. For example, the following [DllImport("user32.dll")] static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); However, I find when interfacing with interesting native interfaces, that have many pointer types, flattening everything into IntPtr makes the code very hard to read and removes the typical typechecking that a compiler can do. I've been using a pattern where I declare an unsafe struct to be an opaque pointer type. I can store this pointer type in a managed object, and the compiler can typecheck it form me. For example: class Foo { unsafe struct FOO {}; // opaque type unsafe FOO *my_foo; class if { [DllImport("mydll")] extern static unsafe FOO* get_foo(); [DllImport("mydll")] extern static unsafe void do_something_foo(FOO *foo); } public unsafe Foo() { this.my_foo = if.get_foo(); } public unsafe do_something_foo() { if.do_something_foo(this.my_foo); } While this example may not seem different than using IntPtr, when there are several pointer types moving between managed and native code, using these opaque pointer types for typechecking is a godsend. I have not run into any trouble using this technique in practice. However, I also have not seen an examples of anyone using this technique, and I wonder why. Is there any reason that the above code is invalid in the eyes of the .NET runtime? My main question is about how the .NET GC system treats "unsafe FOO *my_foo". Is this pointer something the GC system is going to try to trace, or is it simply going to ignore it? My hope is that because the underlying type is a struct, and it's declared unsafe, that the GC would ignore it. However, I don't know for sure. Thoughts?

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  • Elegant Algorithm for Parsing Data Stream Into Record

    - by Matt Long
    I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I have this working, but wondered if anyone has done this before and has a good computer-sciencey way to solve the problem. Here's what I do: Convert the NSData of the current read to an NSString Append the NSString to a placeholder string Check placeholder string for the header (DATA:). If the header is not there, just wait for the next read. If the header exists, append whatever precedes it to a previous record placeholder and hand that placeholder off to an array as a complete record that I can further parse into fields. Take whatever shows up after the header and place it in the record placeholder so that it can be appended to in the next read. Repeat steps 3 - 5. Let me know if you see any flaws with this or have a suggestion for a better way. Seems there should be some design pattern for this, but I can't think of one. Thanks.

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  • Cross-Platform Language + GUI Toolkit for Prototyping Multimedia Applications

    - by msutherl
    I'm looking for a language + GUI toolkit for rapidly prototyping utility applications for multimedia installations. I've been working with Max/MSP/Jitter for many years, but I'd like to add a text-based language to my 'arsenal' for tasks apart from 'content production'. (When it comes to actual media synthesis, my choices are clear [SuperCollider + MSP for audio, Jitter + Quartz + openFrameworks for video]). I'm looking for something that maintains some of the advantages of Max, but is lower-level, faster, more cross-platfrom (Linux support), and text-based. Integration with powerful sound/video libraries is not a requirement. Some requirements: Cross-platform (at least OSX and Linux, Windows is a plus) Fast and easy cross-platform GUIs with no platform-specific modification GUI code separated from backend code as much as possible Good for interfacing with external serial devices (micro-controllers) Good network support (UDP/TCP) Good libraries for multi-media (video, sound, OSC) are a plus Asynchronous synchronous UNIX integration is a plus The options that come to mind: AS3/Flex (not a fan of AS3 or the idea of running in the Flash Player) openFrameworks (C++ framework, perhaps a bit too low level [looking for fast development time] and biased toward video work) Java w/ Processing libraries (like openFrameworks, just slower) Python + Qt (is Qt appropriate for rapid prototyping?) Python + Another GUI toolkit SuperCollider + Swing (yucky GUI development) Java w/ SWT Any other options? What do you recommend?

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  • What kinds of problems are most likely to occur? (question rewritten)

    - by ChrisC
    If I wrote 1) a C# SQL db app (a simple program consisting of a gui over some forms with logic for interfacing with the sql db) 2) for home use, that doesn't do any network communication 3) that uses a simple, reliable, and appropriate sql db 4) whose gui is properly separated from the logic 5) that has complete and dependable input data validation 6) that has been completely tested so that 100% of logic bugs were eliminated ... and then if the program was installed and run by random users on their random Windows computers Q1) What types of technical (non-procedural) problems and support situations are most likely to occur, and how likely are they? Q2) Are there more/other things I could do in the first place to prevent those problems and also minimize the amount of user support required? I know some answers will apply to my specific platforms (C#, SQL, Windows, etc) and some won't. Please be as specific as is possible. Mitch Wheat gave me some very valuable advice below, but I'm now offering the bounty because I am hoping to get a better picture of the kinds of things that I'm most reasonably likely to encounter. Thanks.

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  • Problem with WHERE columnName = Data in MySQL query in C#

    - by Ryan Sullivan
    I have a C# webservice on a Windows Server that I am interfacing with on a linux server with PHP. The PHP grabs information from the database and then the page offers a "more information" button which then calls the webservice and passes in the name field of the record as a parameter. So i am using a WHERE statement in my query so I only pull the extra fields for that record. I am getting the error: System.Data.SqlClient.SqlException:Invalid column name '42' Where 42 is the value from the name field from the database. my query is string selectStr = "SELECT name, castNotes, triviaNotes FROM tableName WHERE name =\"" + show + "\""; I do not know if it is a problem with my query or something is wrong with the database, but here is the rest of my code for reference. NOTE: this all works perfectly when I grab all of the records, but I only want to grab the record that I ask my webservice for. public class ktvService : System.Web.Services.WebService { [WebMethod] public string moreInfo(string show) { string connectionStr = "MyConnectionString"; string selectStr = "SELECT name, castNotes, triviaNotes FROM tableName WHERE name =\"" + show + "\""; SqlConnection conn = new SqlConnection(connectionStr); SqlDataAdapter da = new SqlDataAdapter(selectStr, conn); DataSet ds = new DataSet(); da.Fill(ds, "tableName"); DataTable dt = ds.Tables["tableName"]; DataRow theShow = dt.Rows[0]; string response = "Name: " + theShow["name"].ToString() + "Cast: " + theShow["castNotes"].ToString() + " Trivia: " + theShow["triviaNotes"].ToString(); return response; } }

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  • Leveraging hobby experience to get a job

    - by Bernard
    Like many other's I began programming at an early age. I started when I was 11 and I learned C when I was 14 (now 26). While most of what I did were games just to entertain myself I did everything from low level 2D graphics, and binary I/O, to interfacing with free API's, custom file systems, audio, 3D animations, OpenGL, web sites, etc. I worked on a wide variety of things trying to make various games. Because of this experience I have tested out of every college level C/C++ programming course I have ever been offered. In the classes I took, my classmates would need a week to do what I finished in class with an hour or two of work. I now have my degree now and I have 2 years of experience working full time as a web developer however I would like to get back into C++ and hopefully do simulation programming. Unfortunately I have yet to do C++ as a job, I have only done it for testing out of classes and doing my senior project in college. So most of what I have in C++ is still hobby experience and I don't know how to best convey that so that I don't end up stuck doing something too low level for me. Right now I see a job offer that requires 2 years of C++ experience, but I have at least 9 (I didn't do C++ everyday for the last 14 years). How do I convey my experience? How much is it truly worth? and How do I get it's full value? The best thing that I can think of is a demo and a portfolio, however that only comes into play after an interview has been secured. I used a portfolio to land my current job. All answers and advice are appreciated.

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  • Question regarding ideal database implementation for iPhone app

    - by Jeff
    So I have a question about the ideal setup for an app I am getting ready to build. The app is basically going to be a memorization tool and I already have an sqlite database full of content that I will be using for the app. The user will navigate through the contents of the database(using the uipickerview), and select something for memorization. If that row or cell of data is selected, it is put into a pool or a uitableview that is dedicated to showing which items you have in your "need to memorize" pool. When you go to that tableview, you can select the row, and the actual data would be populated. All information in the tableview would be deletable, in the event that they don't want it there anymore... Thats it. I know that with database interfacing, there are a few different options out there, in this particular setup, is core data the easiest approach? Is there any other way that would be better? I am just kind of looking for a point in the right direction, any help is greatly appreciated!!

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  • Link compatibility between C++ and D

    - by Caspin
    D easily interfaces with C. D just as easily interfaces with C++, but (and it's a big but) the C++ needs to be extremely trivial. The code cannot use: namespaces templates multiple inheritance mix virtual with non-virtual methods more? I completely understand the inheritance restriction. The rest however, feel like artificial limitations. Now I don't want to be able to use std::vector<T> directly, but I would really like to be able to link with std::vector<int> as an externed template. The C++ interfacing page has this particularly depressing comment. D templates have little in common with C++ templates, and it is very unlikely that any sort of reasonable method could be found to express C++ templates in a link-compatible way with D. This means that the C++ STL, and C++ Boost, likely will never be accessible from D. Admittedly I'll probably never need std::vector while coding in D, but I'd love to use QT or boost. So what's the deal. Why is it so hard to express non-trivial C++ classes in D? Would it not be worth it to add some special annotations or something to express at least namespaces?

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  • How do I distribute my slightly customized Linux in VirtualBox?

    - by goodrone
    Suppose I've got some Arch Linux installation which I'd like to distribute among students with (sometimes very) basic Linux knowledge to make them able to compile C programs in an environment very similar to that in the university. (Things like Cygwin or MinGW seem to be inappropriate here.) I also choose VirtualBox as a holder for the virtual system. The question is: how do I distribute it? I mean: installing VirtualBox on the target machine (if not still installed) uncompressing and copying my image file (.VDI) registering the image (so that VirtualBox could see it when launched) configuring the guest system in VirtualBox (network, memory, etc.) optionally installing PuTTY to simplify interfacing with the guest Linux Should I create an installer? Which one? Or just write some .BAT-scripts? (Target host system is Windows, mostly XP and Vista.) I definately don't want to have a webpage with screen shot explaining where to click and what to press, because it's boring. Additionaly, what will be the best (the most user-friendly) way to configure network when the guest Linux system is run for the first time?

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  • C# Sql Connection Best Practises 2013

    - by Pete Petersen
    With the new year approaching I'm drawing up a development plan for 2013. I won't bore you with the details but I started thinking about whether the way I do things is actually the 'correct' way. In particular how I'm interfacing with SQL. I create predominantly create WPF desktop applications and often some Silverlight Web Applications. All of my programs are very Data-Centric. When connecting to SQL from WPF I tend to use Stored Procedures stored on the server and fetch them using ADO.NET (e.g. SQLConnection(), .ExecuteQuery()). However with Silverlight I have a WCF service and use LINQ to SQL (and I'm using LINQ much more in WPF). My question is really is am I doing anything wrong in a sense that it's a little old fashioned? I've tried to look this up online but could find anything useful after about 2010 and of those half were 'LINQ is dead!' and the other 'Always use LINQ' Just want to make sure going forward I'm doing the right things the right way, or at least the advised way :). What principles are you using when connecting to SQL? Is it the same for WPF and Silverlight/WCF?

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  • Prompting for authentication from a wxPython program and passing it along to IIS?

    - by MetaHyperBolic
    I have a client (written in Python, with a wxPython front end in dead-simple wizard style) which communicates a website running IIS. A python script receives requests and does the usual client-server dance. I would have written this as a browser application, but for the requirement that certain things happen on the local PC that the web can't help with (file manipulation, interfacing with certain USB hardware, etc.) Right now, I am simply using the logon credentials, compounded as a string from os.environ['USERDOMAIN'] and os.environ['USERNAME'], to pass along to the server, which connects to Active Directory and enumerates the members of the group, looking for those logon credentials. It's an ugly hack, but it works. Obviously, I could make people log out of the generic helper accounts and log back into Windows using specific accounts. However, I wondered how feasible it would be to provide some kind of logon prompt wherein the user can type in a name and password, then some kind of authorization token could be passed on to IIS. This seems like something I would not want to do myself, given that amateurs almost always make huge security mistakes. Now you can see why I am wishing this was purely web-based. What's a good way to handle this?

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  • Concurrent usage of table causing issues

    - by Sven
    Hello In our current project we are interfacing with a third party data provider. They need to insert data in a table of ours. This inserting can be frequent every 1 min, every 5min, every 30, depends on the amount of new data they need to provide. The use the isolation level read committed. On our end we have an application, windows service, that calls a webservice every 2 minutes to see if there is new data in this table. Our isolation level is repeatable read. We retrieve the records and update a column on these rows. Now the problem is that sometimes this third party provider needs to insert a lot of data, let's say 5000 records. They do this per transaction (5rows per transaction), but they don't close the connection. They do one transaction and then the next untill all records are inserted. This caused issues for our process, we receive a timeout. If this goes on for a long time the database get's completely unstable. For instance, they maybe stopped, but the table somehow still stays unavailable. When I try to do a select on the table, I get several records but at a certain moment I don't get any response anymore. It just says retrieving data but nothing comes anymore until I get a timeout exception. Only solution is to restart the database and then I see the other records. How can we solve this. What is the ideal isolation level setting in this scenario?

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  • 2010 Collaboration Summit Impressions

    - by Elena Zannoni
    It's a bit late, but there you have it anyway. April 14 to 16 I attended the Linux Foundation Collaboration Summit in SFO. I was running two tracks, one on tracing and one on tools. You can see the tracks and the slides here: http://events.linuxfoundation.org/events/collaboration-summit/slides I was pretty busy both days, Thursday with a whole day tracing track, Friday with a half day toolchain track. The sessions were well attended, the rooms were full, with people spilling in the hallways. Some new things were presented, like Kernelshark, by Steve Rostedt, a GUI (yes, believe it or not, a GUI) written in GTK. It is very nice, showing a timeline for traced kernel events, and you can zoom in and filter at will. It works on the latest kernels, and it requires some new things/fixes in GTK. I don't recall exactly what version of GTK though. Dominique Toupin from Ericsson presented something about user requirements for tracing. Mostly though about who's who in the embedded world, and eclipse. Masami and Mathieu presented an update on their work. See their slides. The interesting thing to me was of course the new version of uprobes w/o underlying utrace presented by Jim Keniston. At the end of the session we had a discussion about the future of utrace. Roland wasn't there, butTom Tromey (also from RedHat) collected the feedback. Basically we are at a standstill now that utrace has been rejected yet again. There wasn't much advise that anybody could give, except jokingly, we decided that the only way in is to make it a part of perf events. There needs to be another refactoring, but most of all, this "killer app" that would be enabled because of utrace hasn't materialized yet. We think that having a good debugging story on Linux is enough of a killer app, for instance allowing multiple tracers, and not relying on SIGCHLD etc. I think this wasn't completely clear to the kernel community. Trying to achieve debugging via a gdb stub inside the kernel interfacing to utrace and that is controlled via the gdb remote protocol also lost its appeal (thankfully, since the gdb remote protocol is archaic). Somebody would have to be creative in how to submit utrace. It doesn't have to be called utrace (it was really a random choice, for lack of a letter that was not already used in front of the word "trace"). So basically, I think the ideas behind utrace are sound, and the necessity of a new interface is acknowledged. But I believe the integration/submission process with the kernel folks has to restart from scratch, clean slate. We'll see. There are many conferences and meetings coming up in the near future where things can be discussed further. On the second day, Friday, we had the tools talks. It was interesting to observe the more "kernel" oriented people's behavior towards the gcc etc community. The first talk was by Mark Mitchell, about Gcc and its new plugin architecture. After that, Paolo talked about the new C++1x standard, which will be finalized in 2011. Many features are already implemented in the libstdc++ library and gcc and usable today. We had a few minutes (really, the half day track was quite short) where Bradley Kuhn from the Software Freedom Law Center explained the GPLv3 exception for gcc (due to the new gcc plugin architecture and the availability of the intermediate results from the compilation, which is a new thing). I will not try to explain, but basically you cannot take the result of the preprocessing and then use that in your own proprietary compiler. After, we had a talk by Ian Taylor about the new Gold linker. One good thing in that area is that they are trying to make gold the new default linker (for instance Fedora will use gold as the distro linker). However gold is very different from binutils' old linker. It doesn't use a linker script, for instance. The kernel has been linked with gold many times as an exercise (the ground work was done by Kris Van Hees), but this needs to be constantly tested/monitored because the kernel linker script is very complex, and uses esoteric features (Wenji is now monitoring that each kernel RC can be built with gold). It was positive that people are now aware of gold and the need for it to be ported to more architectures. It seems that the porting is very easy, with little arch dependent code. Finally Tom Tromey presented about gdb and the archer project. Archer is a development branch of gdb mostly done by RedHat, where they are focusing on better c++ printing, c++ expression parsing, and plugins. The archer work is merged regularly in the gdb mainline. In general it was a good conference. I did miss most of the first day, because that's when I flew in. But I caught a couple of talks. Nothing earth shattering, except for Google giving each person registered a free Android phone. Yey.

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  • Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

    - by Henrik
    Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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  • Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

    - by Henrik
    Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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  • Hibernate Communications Link Failure in Hibernate Based Java Servlet application powered by MySQL

    - by Vatsala
    Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?) edit - Here are the c3p0 parameters I tried out - select 1; 2

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  • Hibernate Communications Link Failure in Restlet-Hibernate Based Java application powered by MySQL

    - by Vatsala
    Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?)

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  • Emacs, C++ code completion for vectors

    - by Caglar Toklu
    Hi, I am new to Emacs, and I have the following code as a sample. I have installed GNU Emacs 23.1.1 (i386-mingw-nt6.1.7600), installed cedet-1.0pre7.tar.gz. , installed ELPA, and company. You can find my simple Emacs configuration at the bottom. The problem is, when I type q[0] in main() and press . (dot), I see the 37 members of the vector, not Person although first_name and last_name are expected. The completion works as expected in the function greet() but it has nothing to do with vector. My question is, how can I accomplish code completion for vector elements too? #include <iostream> #include <vector> using namespace std; class Person { public: string first_name; string last_name; }; void greet(Person a_person) { // a_person.first_name is completed as expected! cout << a_person.first_name << "|"; cout << a_person.last_name << endl; }; int main() { vector<Person> q(2); Person guy1; guy1.first_name = "foo"; guy1.last_name = "bar"; Person guy2; guy2.first_name = "stack"; guy2.last_name = "overflow"; q[0] = guy1; q[1] = guy2; greet(guy1); greet(guy2); // cout q[0]. I want to see first_name or last_name here! } My Emacs configuration: ;;; This was installed by package-install.el. ;;; This provides support for the package system and ;;; interfacing with ELPA, the package archive. ;;; Move this code earlier if you want to reference ;;; packages in your .emacs. (when (load (expand-file-name "~/.emacs.d/elpa/package.el")) (package-initialize)) (load-file "~/.emacs.d/cedet/common/cedet.el") (semantic-load-enable-excessive-code-helpers) (require 'semantic-ia) (global-srecode-minor-mode 1) (semantic-add-system-include "/gcc/include/c++/4.4.2" 'c++-mode) (semantic-add-system-include "/gcc/i386-pc-mingw32/include" 'c++-mode) (semantic-add-system-include "/gcc/include" 'c++-mode) (defun my-semantic-hook () (imenu-add-to-menubar "TAGS")) (add-hook 'semantic-init-hooks 'my-semantic-hook)

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