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• Is there any "modern" text editor with command-line/minibuffer?

  - by Pedro Morte Rolo

  A command line in a text editor is a wonderful feature. It allows the user to explore the editor's functionality and learn it's shortcuts in a textual way. It's much faster than using the mouse, and it is much easier to memorise "shortcuts" this way. Emacs and VI provide this, though, emacs and vi are not "modern". By "modern", I mean one that is original built to cope with the modern de-facto standards of selecting, copying, pasting, cutting, undoing, redoing and auto-completing. Cream/vi or Emacs/CUA are not valid options, since there are loads of things built over them that conflict with the mentioned stuff. It would be nice if there was an editor that would cope with the modern de-facto standards out-off-the-box, but still provide a command-line/minibuffer to perform/explore the commands and learn its shortcuts. Is there such a thing? I do not intend to use the "modern" term as derrogatory. I love both Emacs and VI, but I hate their keyboard-shortcut historical baggage. When I reffer to de-facto standards, I am not talking about Windows vs Whatever. Kate, gedit, Eclipse, Intelij or Textmate also follow the norm I am talking about and are not Windows editors. Please do not advertise Vim and Emacs, that's not answering the question. I am asking for alternatives. Why don't I like emacs and vi: Emacs: Despite CUA mode, emacs has loads of modes that conflict with this (e.g. slime, ruby-mode, etc...) It would be nice to have something that would work out-off-the-box. VI: I do not like that it is Visual/Insert-based. I do not know how to browse the text-editor's commands. I do not like that it is so much tought for the terminal. I believe that it has the same problem that I mentioned for emacs. This question is starting to look like requirement analysis.. As de-facto standards I mean: Ctrol-XCV for cut-copy-paste Ctrol-A for select-all Contrl-Z for Undo Ctrol-Y for Redo Control-F for Searching Contrl-Space for auto-complete Shift-arrow for selection Control-arrow for word-navigation Alt-Arrow for moving

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• G++, compiler warnings, c++ templates

  - by Ian

  During the compilatiion of the C++ program those warnings appeared: c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bc:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2317: instantiated from `void std::partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Compare = sortObjects<double>]' c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2506: instantiated from `void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Size = int, _Compare = sortObjects<double>]' c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2589: instantiated from `void std::sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Compare = sortObjects<double>]' io/../structures/objects/../../algorithm/analysis/../../structures/list/ObjectsList.hpp:141: instantiated from `void ObjectsList <T>::sortObjects(unsigned int, T, T, T, T, unsigned int) [with T = double]' I do not why, because all objects have only template parameter T, their local variables are also T. The only place, where I am using double is main. There are objects of type double creating and adding into the ObjectsList... Object <double> o1; ObjectsList <double> olist; olist.push_back(o1); .... T xmin = ..., ymin = ..., xmax = ..., ymax = ...; unsigned int n = ...; olist.sortAllObjects(xmin, ymin, xmax, ymax, n); and comparator template <class T> class sortObjects { private: unsigned int n; T xmin, ymin, xmax, ymax; public: sortObjects ( const T xmin_, const T ymin_, const T xmax_, const T ymax_, const int n_ ) : xmin ( xmin_ ), ymin ( ymin_ ), xmax ( xmax_ ), ymax ( ymax_ ), n ( n_ ) {} bool operator() ( const Object <T> *o1, const Object <T> *o2 ) const { T dmax = (std::max) ( xmax - xmin, ymax - ymin ); T x_max = ( xmax - xmin ) / dmax; T y_max = ( ymax - ymin ) / dmax; ... return ....; } representing ObjectsList method: template <class T> void ObjectsList <T> ::sortAllObjects ( const T xmin, const T ymin, const T xmax, const T ymax, const unsigned int n ) { std::sort ( objects.begin(), objects.end(), sortObjects <T> ( xmin, ymin, xmax, ymax, n ) ); }

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• Checking if an int is prime more efficiently

  - by SipSop

  I recently was part of a small java programming competition at my school. My partner and I have just finished our first pure oop class and most of the questions were out of our league so we settled on this one (and I am paraphrasing somewhat): "given an input integer n return the next int that is prime and its reverse is also prime for example if n = 18 your program should print 31" because 31 and 13 are both prime. Your .class file would then have a test case of all the possible numbers from 1-2,000,000,000 passed to it and it had to return the correct answer within 10 seconds to be considered valid. We found a solution but with larger test cases it would take longer than 10 seconds. I am fairly certain there is a way to move the range of looping from n,..2,000,000,000 down as the likely hood of needing to loop that far when n is a low number is small, but either way we broke the loop when a number is prime under both conditions is found. At first we were looping from 2,..n no matter how large it was then i remembered the rule about only looping to the square root of n. Any suggestions on how to make my program more efficient? I have had no classes dealing with complexity analysis of algorithms. Here is our attempt. public class P3 { public static void main(String[] args){ long loop = 2000000000; long n = Integer.parseInt(args[0]); for(long i = n; i<loop; i++) { String s = i +""; String r = ""; for(int j = s.length()-1; j>=0; j--) r = r + s.charAt(j); if(prime(i) && prime(Long.parseLong(r))) { System.out.println(i); break; } } System.out.println("#"); } public static boolean prime(long p){ for(int i = 2; i<(int)Math.sqrt(p); i++) { if(p%i==0) return false; } return true; } } ps sorry if i did the formatting for code wrong this is my first time posting here. Also the output had to have a '#' after each line thats what the line after the loop is about Thanks for any help you guys offer!!!

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• How can I structure and recode messy categorical data in R?

  - by briandk

  I'm struggling with how to best structure categorical data that's messy, and comes from a dataset I'll need to clean. The Coding Scheme I'm analyzing data from a university science course exam. We're looking at patterns in student responses, and we developed a coding scheme to represent the kinds of things students are doing in their answers. A subset of the coding scheme is shown below. Note that within each major code (1, 2, 3) are nested non-unique sub-codes (a, b, ...). What the Raw Data Looks Like I've created an anonymized, raw subset of my actual data which you can view here. Part of my problem is that those who coded the data noticed that some students displayed multiple patterns. The coders' solution was to create enough columns (reason1, reason2, ...) to hold students with multiple patterns. That becomes important because the order (reason1, reason2) is arbitrary--two students (like student 41 and student 42 in my dataset) who correctly applied "dependency" should both register in an analysis, regardless of whether 3a appears in the reason column or the reason2 column. How Can I Best Structure Student Data? Part of my problem is that in the raw data, not all students display the same patterns, or the same number of them, in the same order. Some students may do just one thing, others may do several. So, an abstracted representation of example students might look like this: Note in the example above that student002 and student003 both are coded as "1b", although I've deliberately shown the order as different to reflect the reality of my data. My (Practical) Questions Should I concatenate reason1, reason2, ... into one column? How can I (re)code the reasons in R to reflect the multiplicity for some students? Thanks I realize this question is as much about good data conceptualization as it is about specific features of R, but I thought it would be appropriate to ask it here. If you feel it's inappropriate for me to ask the question, please let me know in the comments, and stackoverflow will automatically flood my inbox with sadface emoticons. If I haven't been specific enough, please let me know and I'll do my best to be clearer.

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• PDF Report generation

  - by IniTech

  EDIT : I completed this project using ABCpdf. For anyone interested, I love this product and their support is A+. Everything I listed as a 'Con' for the HTML - PDF solution was easily doable in ABCpdf. I've been charged with creating a data driven pdf report. After reviewing the plethora of options, I have narrowed it down to 2. I need you all to to help me decide, or offer alternatives I haven't considered. Here are the requirements: 100% Data driven Eventually PDF (a stop in HTML is fine, so long as it is converted) Can be run with multiple sets of data (the layout is always the same, the data is variable) Contains normal analysis-style copy (saved in DB with html markup) Contains tables (data for tables is generated at run-time) Header/Page # on each page Table of Contents .NET (VB or C#) Done quickly Now, because of the fact that the report is going to be generated with multiple sets of data, I don't think a stamped pdf template will work since I won't know how long or how many pages a certain piece of the report could require. So, I think my best options are: Programmatic creation using an iText-like solution. Generate in HTML and convert to PDF using a third-party application (ABCPdf is the tool I have played with so far) Both solutions have their pro's and con's. Programmatic solution: Pros: Flexible Easy page numbering/page header/table of contents Free Cons: Time consuming (to write a layer on top of iText to do what I need and keep maintainable) Since the copy is already stored in the db with html markup, I would have to parse through the data before I place it into the pdf, ensuring I don't have to break the paragraph into chunks so I can apply bold, italic, underline, etc. to specific phrases. This seems like a huge PITA, and I hope I am wrong about that assumption. HTML - PDF Pros: Easy to generate from db (no parsing necessary) Many tools for conversion Uses technology I am already familiar with Built-in "Print Preview" - not a req, but nice Cons: (Edited after project completion. All of my assumptions were incorrect and ABCpdf is awesome) 1. Almost impossible to generate page headers - Not True 2. Very difficult to generate page numbers Not True 3. Nearly impossible to generate table of contents Not True 4. (Cross-browser support isn't a con; Since its internal, I can dictate what browser to use) 5. Conversion tool quirks - may not convert exactly as rendered in browser Not True 6. Overall, I think it would be very hard to format the HTML exactly as I would want it to appear/convert to PDF. Not True That's it - I need the communitys help in deciding which way I should go. I might be wrong about some of my Pro/Con assumptions. If I am, please tell me. All thoughts and suggestions are welcome and appreciated. Thanks

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• Is "Systems Designer" the job title that best describes what I do? [closed]

  - by ivo-rossi

  After having worked as Java developer for almost 3 years in the same company that I currently work at, I moved to a new position associated with the development of the same application. I’m in this new position for more than 1 year now. My official job title is Systems Designer, but I’m not sure this is a title that expresses well what I do. So my question here is what would be the most appropriate job title for me? I see this question as important for my career development. After all, I should be able to explain in one word what I do. And it’s no longer “Java Developer”. Well, in more than one word, this is what I do: The business analysts gather requirements / business problems to be solved with the clients and then discuss these requirements with me. Given the requirements, I design the high level solutions to be implemented in our system (e.g. a new screen on the client application, modifications to existing reports, extension to the XML export format of some objects, etc). I base my decision on the current capabilities of the system, the overall impact that the solutions would have on the system and the estimated effort to implement them (as I was a developer of this same application for almost 3 years before I moved to this position, I’m confident in my estimates). The solutions are discussed iteratively with the business analysts until we agree that they are good. The outcome of this analysis is what we call the “requirements design” document, which is written by me, shared with clients for approval and then also with the team that is going to implement the solutions and test them. Note that there are a few problems that I need to find a solution for that are non-functional. If the users are unhappy with the performance of a certain tool, I will investigate what can be done to speed it up. I will do some research – often based in the Java code itself - to identify possibilities of optimizations. But in this new position I no longer code, the main outcome of my work is really the “requirements design”. Is “Systems Designer” really the most appropriate job title?

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• Memory Leak with Swing Drag and Drop

  - by tom

  I have a JFrame that accepts top-level drops of files. However after a drop has occurred, references to the frame are held indefinitely inside some Swing internal classes. I believe that disposing of the frame should release all of its resources, so what am I doing wrong? Example import java.awt.datatransfer.DataFlavor; import java.io.File; import java.util.List; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.TransferHandler; public class DnDLeakTester extends JFrame { public static void main(String[] args) { new DnDLeakTester(); //Prevent main from returning or the jvm will exit while (true) { try { Thread.sleep(10000); } catch (InterruptedException e) { } } } public DnDLeakTester() { super("I'm leaky"); add(new JLabel("Drop stuff here")); setTransferHandler(new TransferHandler() { @Override public boolean canImport(final TransferSupport support) { return (support.isDrop() && support .isDataFlavorSupported(DataFlavor.javaFileListFlavor)); } @Override public boolean importData(final TransferSupport support) { if (!canImport(support)) { return false; } try { final List<File> files = (List<File>) support.getTransferable().getTransferData(DataFlavor.javaFileListFlavor); for (final File f : files) { System.out.println(f.getName()); } } catch (Exception e) { e.printStackTrace(); } return true; } }); setDefaultCloseOperation(DISPOSE_ON_CLOSE); pack(); setVisible(true); } } To reproduce, run the code and drop some files on the frame. Close the frame so it's disposed of. To verify the leak I take a heap dump using JConsole and analyse it with the Eclipse Memory Analysis tool. It shows that sun.awt.AppContext is holding a reference to the frame through its hashmap. It looks like TransferSupport is at fault. What am I doing wrong? Should I be asking the DnD support code to clean itself up somehow? I'm running JDK 1.6 update 19.

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• Persistent (purely functional) Red-Black trees on disk performance

  - by Waneck

  I'm studying the best data structures to implement a simple open-source object temporal database, and currently I'm very fond of using Persistent Red-Black trees to do it. My main reasons for using persistent data structures is first of all to minimize the use of locks, so the database can be as parallel as possible. Also it will be easier to implement ACID transactions and even being able to abstract the database to work in parallel on a cluster of some kind. The great thing of this approach is that it makes possible implementing temporal databases almost for free. And this is something quite nice to have, specially for web and for data analysis (e.g. trends). All of this is very cool, but I'm a little suspicious about the overall performance of using a persistent data structure on disk. Even though there are some very fast disks available today, and all writes can be done asynchronously, so a response is always immediate, I don't want to build all application under a false premise, only to realize it isn't really a good way to do it. Here's my line of thought: - Since all writes are done asynchronously, and using a persistent data structure will enable not to invalidate the previous - and currently valid - structure, the write time isn't really a bottleneck. - There are some literature on structures like this that are exactly for disk usage. But it seems to me that these techniques will add more read overhead to achieve faster writes. But I think that exactly the opposite is preferable. Also many of these techniques really do end up with a multi-versioned trees, but they aren't strictly immutable, which is something very crucial to justify the persistent overhead. - I know there still will have to be some kind of locking when appending values to the database, and I also know there should be a good garbage collecting logic if not all versions are to be maintained (otherwise the file size will surely rise dramatically). Also a delta compression system could be thought about. - Of all search trees structures, I really think Red-Blacks are the most close to what I need, since they offer the least number of rotations. But there are some possible pitfalls along the way: - Asynchronous writes -could- affect applications that need the data in real time. But I don't think that is the case with web applications, most of the time. Also when real-time data is needed, another solutions could be devised, like a check-in/check-out system of specific data that will need to be worked on a more real-time manner. - Also they could lead to some commit conflicts, though I fail to think of a good example of when it could happen. Also commit conflicts can occur in normal RDBMS, if two threads are working with the same data, right? - The overhead of having an immutable interface like this will grow exponentially and everything is doomed to fail soon, so this all is a bad idea. Any thoughts? Thanks! edit: There seems to be a misunderstanding of what a persistent data structure is: http://en.wikipedia.org/wiki/Persistent_data_structure

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• Design patterns and interview question

  - by user160758

  When I was learning to code, I read up on the design patterns like a good boy. Long after this, I started to actually understand them. Design discussions such as those on this site constantly try to make the rules more and more general, which is good. But there is a line, over which it becomes over-analysis starts to feed off itself and as such I think begins to obfuscate the original point - for example the "What's Alternative to Singleton" post and the links contained therein. http://stackoverflow.com/questions/1300655/whats-alternative-to-singleton I say this having been asked in both interviews I’ve had over the last 2 weeks what a singleton is and what criticisms I have of it. I have used it a few times for items such as user data (simple key-value eg. last file opened by this user) and logging (very common i'm sure). I've never ever used it just to have what is essentially global application data, as this is clearly stupid. In the first interview, I reply that I have no criticisms of it. He seemed disappointed by this but as the job wasn’t really for me, I forgot about it. In the next one, I was asked again and, as I wanted this job, I thought about it on the spot and made some objections, similar to those contained in the post linked to above (I suggested use of a factory or dependency injection instead). He seemed happy with this. But my problem is that I have used the singleton without ever using it in this kind of stupid way, which I had to describe on the spot. Using it for global data and the like isn’t something I did then realised was stupid, or read was stupid so didn’t do, it was just something I knew was stupid from the start. Essentially I’m supposed to be able to think of ways of how to misuse a pattern in the interview? Which class of programmers can best answer this question? The best ones? The medium ones? I'm not sure.... And these were both bright guys. I read more than enough to get better at my job but had never actually bothered to seek out criticisms of the most simple of the design patterns like this one. Do people think such questions are valid and that I ought to know the objections off by heart? Or that it is reasonable to be able to work out what other people who are missing the point would do on the fly? Or do you think I’m at least partially right that the question is too unsubtle and that the questions ought to be better thought out in order to make sure only good candidates can answer. PS. Please don’t think I’m saying that I’m just so clever that I know everything automatically - I’ve learnt the hard way like everyone else. But avoiding global data is hardly revolutionary.

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• gcc optimization? bug? and its practial implication to project

  - by kumar_m_kiran

  Hi All, My questions are divided into three parts Question 1 Consider the below code, #include <iostream> using namespace std; int main( int argc, char *argv[]) { const int v = 50; int i = 0X7FFFFFFF; cout<<(i + v)<<endl; if ( i + v < i ) { cout<<"Number is negative"<<endl; } else { cout<<"Number is positive"<<endl; } return 0; } No specific compiler optimisation options are used or the O's flag is used. It is basic compilation command g++ -o test main.cpp is used to form the executable. The seemingly very simple code, has odd behaviour in SUSE 64 bit OS, gcc version 4.1.2. The expected output is "Number is negative", instead only in SUSE 64 bit OS, the output would be "Number is positive". After some amount of analysis and doing a 'disass' of the code, I find that the compiler optimises in the below format - Since i is same on both sides of comparison, it cannot be changed in the same expression, remove 'i' from the equation. Now, the comparison leads to if ( v < 0 ), where v is a constant positive, So during compilation itself, the else part cout function address is added to the register. No cmp/jmp instructions can be found. I see that the behaviour is only in gcc 4.1.2 SUSE 10. When tried in AIX 5.1/5.3 and HP IA64, the result is as expected. Is the above optimisation valid? Or, is using the overflow mechanism for int not a valid use case? Question 2 Now when I change the conditional statement from if (i + v < i) to if ( (i + v) < i ) even then, the behaviour is same, this atleast I would personally disagree, since additional braces are provided, I expect the compiler to create a temporary built-in type variable and them compare, thus nullify the optimisation. Question 3 Suppose I have a huge code base, an I migrate my compiler version, such bug/optimisation can cause havoc in my system behaviour. Ofcourse from business perspective, it is very ineffective to test all lines of code again just because of compiler upgradation. I think for all practical purpose, these kinds of error are very difficult to catch (during upgradation) and invariably will be leaked to production site. Can anyone suggest any possible way to ensure to ensure that these kind of bug/optimization does not have any impact on my existing system/code base? PS : When the const for v is removed from the code, then optimization is not done by the compiler. I believe, it is perfectly fine to use overflow mechanism to find if the variable is from MAX - 50 value (in my case).

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• Are there compelling reasons not to use Groovy?

  - by Leonard H Martin

  I'm developing a LoB application in Java after a long absence from the platform (having spent the last 8 years or so entrenched in Fortran, C, a smidgin of C++ and latterly .Net). Java, the language, is not much changed from how I remember it. I like it's strengths and I can work around its weaknesses - the platform has grown and deciding upon the myriad of different frameworks which appear to do much the same thing as one another is a different story; but that can wait for another day - all-in-all I'm comfortable with Java. However, over the last couple of weeks I've become enamoured with Groovy, and purely from a selfish point of view: but not just because it makes development against the JVM a more succinct and entertaining (and, well, "groovy") proposition than Java (the language). What strikes me most about Groovy is its inherent maintainability. We all (I hope!) strive to write well documented, easy to understand code. However, sometimes the languages we use themselves defeat us. An example: in 2001 I wrote a library in C to translate EDIFACT EDI messages into ANSI X12 messages. This is not a particularly complicated process, if slightly involved, and I thought at the time I had documented the code properly - and I probably had - but some six years later when I revisited the project (and after becoming acclimatised to C#) I found myself lost in so much C boilerplate (mallocs, pointers, etc. etc.) that it took three days of thoughtful analysis before I finally understood what I'd been doing six years previously. This evening I've written about 2000 lines of Java (it is the day of rest, after all!). I've documented as best as I know how, but, but, of those 2000 lines of Java a significant proportion is Java boiler plate. This is where I see Groovy and other dynamic languages winning through - maintainability and later comprehension. Groovy lets you concentrate on your intent without getting bogged down on the platform specific implementation; it's almost, but not quite, self documenting. I see this as being a huge boon to me when I revisit my current project (which I'll port to Groovy asap) in several years time and to my successors who will inherit it and carry on the good work. So, are there any reasons not to use Groovy?

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• In R, how do you get the best fitting equation to a set of data?

  - by Matherion

  I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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• What are the rules governing how a bind variable can be used in Postgres and where is this defined?

  - by Craig Miles

  I can have a table and function defined as: CREATE TABLE mytable ( mycol integer ); INSERT INTO mytable VALUES (1); CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol = l_myvar; RETURN l_myrow; END; $$ LANGUAGE plpgsql; In this case l_myvar acts as a bind variable for the value passed when I call: SELECT * FROM myfunction(1); and returns the row where mycol = 1 If I redefine the function as: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (l_myvar); RETURN l_myrow; END; $$ LANGUAGE plpgsql; SELECT * FROM myfunction(1); still returns the row where mycol = 1 However, if I now change the function definition to allow me to pass an integer array and try to this array in the IN clause, I get an error: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer[]) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (array_to_string(l_myvar, ',')); RETURN l_myrow; END; $$ LANGUAGE plpgsql; Analysis reveals that although: SELECT array_to_string(ARRAY[1, 2], ','); returns 1,2 as expected SELECT * FROM myfunction(ARRAY[1, 2]); returns the error operator does not exist: integer = text at the line: WHERE mycol IN (array_to_string(l_myvar, ',')); If I execute: SELECT * FROM mytable WHERE mycol IN (1,2); I get the expected result. Given that array_to_string(l_myvar, ',') evaluates to 1,2 as shown, why arent these statements equivalent. From the error message it is something to do with datatypes, but doesnt the IN(variable) construct appear to be behaving differently from the = variable construct? What are the rules here? I know that I could build a statement to EXECUTE, treating everything as a string, to achieve what I want to do, so I am not looking for that as a solution. I do want to understand though what is going on in this example. Is there a modification to this approach to make it work, the particular example being to pass in an array of values to build a dynamic IN clause without resorting to EXECUTE? Thanks in advance Craig

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• Is throwing an exception a healthy way to exit?

  - by ramaseshan

  I have a setup that looks like this. class Checker { // member data Results m_results; // see below public: bool Check(); private: bool Check1(); bool Check2(); // .. so on }; Checker is a class that performs lengthy check computations for engineering analysis. Each type of check has a resultant double that the checker stores. (see below) bool Checker::Check() { // initilisations etc. Check1(); Check2(); // ... so on } A typical Check function would look like this: bool Checker::Check1() { double result; // lots of code m_results.SetCheck1Result(result); } And the results class looks something like this: class Results { double m_check1Result; double m_check2Result; // ... public: void SetCheck1Result(double d); double GetOverallResult() { return max(m_check1Result, m_check2Result, ...); } }; Note: all code is oversimplified. The Checker and Result classes were initially written to perform all checks and return an overall double result. There is now a new requirement where I only need to know if any of the results exceeds 1. If it does, subsequent checks need not be carried out(it's an optimisation). To achieve this, I could either: Modify every CheckN function to keep check for result and return. The parent Check function would keep checking m_results. OR In the Results::SetCheckNResults(), throw an exception if the value exceeds 1 and catch it at the end of Checker::Check(). The first is tedious, error prone and sub-optimal because every CheckN function further branches out into sub-checks etc. The second is non-intrusive and quick. One disadvantage is I can think of is that the Checker code may not necessarily be exception-safe(although there is no other exception being thrown anywhere else). Is there anything else that's obvious that I'm overlooking? What about the cost of throwing exceptions and stack unwinding? Is there a better 3rd option?

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• How to ensure structures are completly initialized (by name) in GCC?

  - by Steven Spark

  How do I ensure each and every field of my structures are initialized in GCC when using designated initializers? (I'm especially interested in function pointers.) (I'm using C not C++.) Here is an example: typedef struct { int a; int b; } foo_t; typedef struct { void (*Start)(void); void (*Stop)(void); } bar_t; foo_t fooo = { 5 }; foo_t food = { .b=4 }; bar_t baro = { NULL }; bar_t bard = { .Start = NULL }; -Wmissing-field-initializers does not help at all. It works for fooo only in GCC (mingw 4.7.3, 4.8.1), and clang does only marginally better (no warnings for food and bard). I'm sure there is a reason for not producing warnings for designated initializer (even when I explicitly ask for them) but I want/need them. I do not want to initialize structures based on order/position because that is more error prone (for example swapping Start and Stop won't even give any warning). And neither gcc nor clang will give any warning that I failed to explicitly initialize a field (when initializing by name). I also don't want to litter my code with if(x.y==NULL) lines for multiple reasons, one of which is I want compile time warnings and not runtime errors. At least splint will give me warnings on all 4 cases, but unfortunately I cannot use splint all the time (it chokes on some of the code (fails to parse some C99, GCC extensions)). Note: If I'm using a real function instead of NULL GCC will also show a warning for baro (but not bard). I searched google and stack overflow but only found related questions and have not found answer for this specific problem. The best match I have found is 'Ensure that all elements in a structure are initialized' Ensure that all elements in a structure are initialized Which asks pretty much the same question, but has no satisfying answer. Is there a better way dealing with this that I have not mentioned? (Maybe other code analysis tool? Preferably something (free) that can be integrated into Eclipse or Visual Studio...)

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• HP SmartArray P400: How to repair failed logical drive?

  - by TegtmeierDE

  I have a HP Server with SmartArray P400 controller (incl. 256 MB Cache/Battery Backup) with a logicaldrive with replaced failed physicaldrive that does not rebuild. This is how it looked when I detected the error: ~# /usr/sbin/hpacucli ctrl slot=0 show config Smart Array P400 in Slot 0 (Embedded) (sn: XXXX) array A (SATA, Unused Space: 0 MB) logicaldrive 1 (698.6 GB, RAID 1, OK) physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SATA, 750 GB, OK) physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SATA, 750 GB, OK) array B (SATA, Unused Space: 0 MB) logicaldrive 2 (2.7 TB, RAID 5, Failed) physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SATA, 750 GB, OK) physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SATA, 750 GB, OK) physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SATA, 750 GB, OK) physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SATA, 750 GB, Failed) physicaldrive 2I:1:7 (port 2I:box 1:bay 7, SATA, 750 GB, OK) unassigned physicaldrive 2I:1:8 (port 2I:box 1:bay 8, SATA, 750 GB, OK) ~# I thought that I had drive 2I:1:8 configured as a spare for Array A and Array B, but it seems this was not the case :-(. I noticed the problem due to I/O errors on the host, even if only 1 physicaldrive of the RAID5 is failed. Does someone know why this could happen? The logicaldrive should go into "Degraded" mode but still be fully accessible from the host os!? I first tried to add the unassigned drive 2I:1:8 as a spare to logicaldrive 2, but this was not possible: ~# /usr/sbin/hpacucli ctrl slot=0 array B add spares=2I:1:8 Error: This operation is not supported with the current configuration. Use the "show" command on devices to show additional details about the configuration. ~# Interestingly it is possible to add the unassigned drive to the first array without problems. I thought maybe the controller put the array into "failed" state due to the missing spare and protects failed arrays from modification. So I tried was to reenable the logicaldrive (to add the spare afterwards): ~# /usr/sbin/hpacucli ctrl slot=0 ld 2 modify reenable Warning: Any previously existing data on the logical drive may not be valid or recoverable. Continue? (y/n) y Error: This operation is not supported with the current configuration. Use the "show" command on devices to show additional details about the configuration. ~# But as you can see, re-enabling the logicaldrive this was not possible. Now I replaced the failed drive by hotswapping it with the unassigned drive. The status now looks like this: ~# /usr/sbin/hpacucli ctrl slot=0 show config Smart Array P400 in Slot 0 (Embedded) (sn: XXXX) array A (SATA, Unused Space: 0 MB) logicaldrive 1 (698.6 GB, RAID 1, OK) physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SATA, 750 GB, OK) physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SATA, 750 GB, OK) array B (SATA, Unused Space: 0 MB) logicaldrive 2 (2.7 TB, RAID 5, Failed) physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SATA, 750 GB, OK) physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SATA, 750 GB, OK) physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SATA, 750 GB, OK) physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SATA, 750 GB, OK) physicaldrive 2I:1:7 (port 2I:box 1:bay 7, SATA, 750 GB, OK) ~# The logical drive is still not accessible. Why is it not rebuilding? What can I do? FYI, this is the configuration of my controller: ~# /usr/sbin/hpacucli ctrl slot=0 show Smart Array P400 in Slot 0 (Embedded) Bus Interface: PCI Slot: 0 Serial Number: XXXX Cache Serial Number: XXXX RAID 6 (ADG) Status: Enabled Controller Status: OK Chassis Slot: Hardware Revision: Rev E Firmware Version: 5.22 Rebuild Priority: Medium Expand Priority: Medium Surface Scan Delay: 15 secs Surface Analysis Inconsistency Notification: Disabled Raid1 Write Buffering: Disabled Post Prompt Timeout: 0 secs Cache Board Present: True Cache Status: OK Accelerator Ratio: 25% Read / 75% Write Drive Write Cache: Disabled Total Cache Size: 256 MB No-Battery Write Cache: Disabled Cache Backup Power Source: Batteries Battery/Capacitor Count: 1 Battery/Capacitor Status: OK SATA NCQ Supported: True ~# Thanks for you help in advance.

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• Fedora 12 Wireless problems (Intel Wireless 4965AGN Card)

  - by Ninefingers

  Hi All, I'm having an interesting experience with my wireless card at the moment. Basically, it does like this: I connect to the local wireless network (netgear router) It works, briefly, allowing me to browse a webpage or maybe two, if I'm lucky. It then stops working / sending any packets, whilst reported still connected. Now, me being me I've had a look to see what I can find. wpa_supplicant.log looks like this: Trying to associate with valid_mac:a2:30 (SSID='vennardwireless' freq=2462 MHz) Associated with valid_mac:a2:30 WPA: Key negotiation completed with valid_mac:a2:30 [PTK=CCMP GTK=TKIP] CTRL-EVENT-CONNECTED - Connection to valid_mac:a2:30 completed (reauth) [id=0 id_str=] CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys So that's working fine. dmesg | grep "*iwl*" spits out this: iwlagn: Intel(R) Wireless WiFi Link AGN driver for Linux, 1.3.27kds iwlagn: Copyright(c) 2003-2009 Intel Corporation iwlagn 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 iwlagn 0000:03:00.0: setting latency timer to 64 iwlagn 0000:03:00.0: Detected Intel Wireless WiFi Link 4965AGN REV=0x4 iwlagn 0000:03:00.0: Tunable channels: 13 802.11bg, 19 802.11a channels iwlagn 0000:03:00.0: irq 32 for MSI/MSI-X phy0: Selected rate control algorithm 'iwl-agn-rs' iwlagn 0000:03:00.0: firmware: requesting iwlwifi-4965-2.ucode iwlagn 0000:03:00.0: loaded firmware version 228.61.2.24 Registered led device: iwl-phy0::radio Registered led device: iwl-phy0::assoc Registered led device: iwl-phy0::RX Registered led device: iwl-phy0::TX iwlagn 0000:03:00.0: iwl_tx_agg_start on ra = 00:24:b2:32:a3:30 tid = 0 iwlagn 0000:03:00.0: iwl_tx_agg_start on ra = 00:24:b2:32:a3:30 tid = 0 So that's working too. I can also ping 192.168.0.1 -I wlan0 and arping 192.168.0.1 -I wlan0 the router until the network falls over. uname -r:2.6.32.10-90.fc12.x86_64. Laptop is a Core2 Duo (2Ghz) with 3GB RAM. Other symptoms I've noticed are that wireshark freezes when I capture on the "broken" interface until I disconnect. Am using networkmanager as per normal. Stupidly, I can connect to the same router via eth0/a cat6 cable just fine. Everyone else can connect to the AP fine (from Windows). Yes, I'm sat right next to it and not trying to access a hotspot the other side of the world. Any ideas? Is this a broken update? (I intend to reboot and test an older kernel later)? Anyone else come across this? Edit: iwconfig wlan0 rate auto is the settings I'm using for rates. Also, according to networkmanager the network is still connected. Thanks for any pointers / advice.

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• Unix sort keys cause performance problems

  - by KenFar

  My data: It's a 71 MB file with 1.5 million rows. It has 6 fields All six fields combine to form a unique key - so that's what I need to sort on. Sort statement: sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 -k6,6 -o output.csv input.csv The problem: If I sort without keys, it takes 30 seconds. If I sort with keys, it takes 660 seconds. I need to sort with keys to keep this generic and useful for other files that have non-key fields as well. The 30 second timing is fine, but the 660 is a killer. More details using unix time: sort input.csv -o output.csv = 28 seconds sort -t ',' -k1 input.csv -o output.csv = 28 seconds sort -t ',' -k1,1 input.csv -o output.csv = 64 seconds sort -t ',' -k1,1 -k2,2 input.csv -o output.csv = 194 seconds sort -t ',' -k1,1 -k2,2 -k3,3 input.csv -o output.csv = 328 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 input.csv -o output.csv = 483 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 input.csv -o output.csv = 561 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 -k6,6 input.csv -o output.csv = 660 seconds I could theoretically move the temp directory to SSD, and/or split the file into 4 parts, sort them separately (in parallel) then merge the results, etc. But I'm hoping for something simpler since looks like sort is just picking a bad algorithm. Any suggestions? Testing Improvements using buffer-size: With 2 keys I got a 5% improvement with 8, 20, 24 MB and best performance of 8% improvement with 16MB, but 6% worse with 128MB With 6 keys I got a 5% improvement with 8, 20, 24 MB and best performance of 9% improvement with 16MB. Testing improvements using dictionary order (just 1 run each): sort -d --buffer-size=8M -t ',' -k1,1 -k2,2 input.csv -o output.csv = 235 seconds (21% worse) sort -d --buffer-size=8M -t ',' -k1,1 -k2,2 input.csv -o ouput.csv = 232 seconds (21% worse) conclusion: it makes sense that this would slow the process down, not useful Testing with different file system on SSD - I can't do this on this server now. Testing with code to consolidate adjacent keys: def consolidate_keys(key_fields, key_types): """ Inputs: - key_fields - a list of numbers in quotes: ['1','2','3'] - key_types - a list of types of the key_fields: ['integer','string','integer'] Outputs: - key_fields - a consolidated list: ['1,2','3'] - key_types - a list of types of the consolidated list: ['string','integer'] """ assert(len(key_fields) == len(key_types)) def get_min(val): vals = val.split(',') assert(len(vals) <= 2) return vals[0] def get_max(val): vals = val.split(',') assert(len(vals) <= 2) return vals[len(vals)-1] i = 0 while True: try: if ( (int(get_max(key_fields[i])) + 1) == int(key_fields[i+1]) and key_types[i] == key_types[i+1]): key_fields[i] = '%s,%s' % (get_min(key_fields[i]), key_fields[i+1]) key_types[i] = key_types[i] key_fields.pop(i+1) key_types.pop(i+1) continue i = i+1 except IndexError: break # last entry return key_fields, key_types While this code is just a work-around that'll only apply to cases in which I've got a contiguous set of keys - it speeds up the code by 95% in my worst case scenario.

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• How to set up a mini call center?

  - by Ralph

  I'm trying to figure out how to set up a miniature call center for a small business. Like, for 1-4 people to take calls, but hopefully expandable to more. We want to accept nation-wide calls, and then I guess distribute the calls among the available agents. If no one is available, I guess it should either put them in a queue and play some annoying music for them, or forward to call to an agent who has least-recently taken a call who can then quickly answer and say "please hold" until they're done their call. We want to have one phone number that customers can call. I guess we then need some kind of ACD system which would take each call and forward it to an agent based on some algorithm? Then we would need to purchase a separate phone line for each agent, plus one just for the distributor? Or do we need several "extra" lines to maintain a queue (one for each customer waiting too)? This "ACD" thing, is it just a device that you would plug a phone line into (or several?), and maybe connect to a computer, aided by some software? Or is a subscription thing that I would need from my local telephone provider? Next, the business we're running, the callers will be repeat customers. It would be helpful to automatically pull up their profile based on the incoming number. The "software" our agents will be running will just be a website where they can log in (preferably from home) and then enter some information they would obtain through the call. So, the system would have to somehow interface with the website if possible. If not, we'll just have to ask each customer for an identifier (phone number, username, customer number, or something). Is this possible? I guess each computer would need a device that the call would pass through, and then if I can somehow hook into that, then I can write some software that will interface with the site. So, where do I start? What hardware do we need to buy? What subscriptions do we need? We were thinking this magicJack might help us in accepting long-distance calls for cheaper, but my understanding is that they provide you with some weird-looking number, is there a way we could "mask" it with our toll-free number? And then pass the incoming calls through the distributor system, which would then get passed to the call-accepting device which would both allow an agent to answer the call and have a software hook? (I realize this might be partially out of the scope of SU, but I wasn't sure where else to ask. It is about computer(-aided) hardware and software anyway.) P.S.: I don't need any of that "press 1 to talk to..." or "say xyz to..." junk. Just a straight-forward, connect-to-next-available-agent system.

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• Linux boot on a raid1 software raid ?

  - by azera

  Hello I am trying to convert my single disk boot to a raid1 boot So far here is what i have: I sucessfully create the raid 1 as degraded with the new drive alone, I copied all the data on it I can mount that raid 1, see its files etc I already have a raid5 that is working on the same box (although not booting on it) I have installed grub on both drive When grub boot, it loads the kernel alright, but during the kernel boot it fails to load the "root block device" The kernel tells me : 1 - detected that root device is an md device 2 - determining root devices 3 - mounting root 4 - mounting /dev/md125 on /newroot failed: input/output error. Please enter another root device: ... At this point, if I enter /dev/sda3 (my "old" root device that isn't converted to raid yet) everything boots fine without the root. The /dev/md125 device is indeed created but it seems to be created after the error happens, as in it creates it after loading the device, when mdadm is loaded. Somehow it looks like it can't/doesn't load the raid array before it needs to mount it, and I don't know how I can solve that. My config files (taken from the system once it boots with sda3 as root device): $ cat /etc/mdadm.conf ARRAY /dev/md/md0-r5 metadata=0.90 UUID=1a118934:c831bdb3:64188b84:66721085 ARRAY /dev/md125 metadata=0.90 UUID=48ec4190:a80d4dde:64188b84:66721085 $ cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] [raid0] [raid10] md125 : active raid1 sdc3[1] 477853312 blocks [2/1] [_U] md127 : active raid5 sdd[0] sdf[3] sdb[2] sde[1] 4395415488 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] unused devices: <none> $ cat /boot/grub/menu.lst default 0 timeout 8 splashimage=(hd0,0)/boot/grub/splash.xpm.gz title Gentoo Linux 2.6.31-r10 root (hd0,0) #kernel /boot/kernel-genkernel-x86_64-2.6.31-gentoo-r10 root=/dev/ram0 real_root=/dev/sda3 kernel /boot/kernel-genkernel-x86_64-2.6.31-gentoo-r10 root=/dev/md125 md=125,/dev/sdc3,/dev/sda3 initrd /boot/initramfs-genkernel-x86_64-2.6.31-gentoo-r10 # blkid /dev/sda1: UUID="89fee223-b845-4e0a-8a0b-e6cf695d5bcf" TYPE="ext2" /dev/sda2: UUID="a72296a8-d7d4-447f-a34b-ee920fd1a767" TYPE="swap" /dev/sda3: UUID="97eb0a6a-c385-4a9d-bf74-c0bab1fa4dc1" TYPE="ext3" /dev/sdb: UUID="1a118934-c831-bdb3-6418-8b8466721085" TYPE="linux_raid_member" /dev/sdc1: UUID="d36537fd-19a0-b8a3-6418-8b8466721085" TYPE="linux_raid_member" /dev/sdd: UUID="1a118934-c831-bdb3-6418-8b8466721085" TYPE="linux_raid_member" /dev/sde: UUID="1a118934-c831-bdb3-6418-8b8466721085" TYPE="linux_raid_member" /dev/md127: UUID="13a41589-4cf1-4c04-91ca-37484182c783" TYPE="ext4" /dev/sdf: UUID="1a118934-c831-bdb3-6418-8b8466721085" TYPE="linux_raid_member" /dev/sdc2: UUID="a1916397-1b48-45d7-9f98-73aa521e882f" TYPE="swap" /dev/sdc3: UUID="48ec4190-a80d-4dde-6418-8b8466721085" TYPE="linux_raid_member" /dev/md125: UUID="c947ed64-1d4d-4d1d-b4d2-24669fff916e" SEC_TYPE="ext2" TYPE="ext3" # mdadm -E mdadm: No devices to examine # fdisk -l Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0xe975e9fc Device Boot Start End Blocks Id System /dev/sda1 1 5 40131 83 Linux /dev/sda2 6 1311 10490445 82 Linux swap / Solaris /dev/sda3 1312 60801 477853425 83 Linux Disk /dev/sdc: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0xe975e9fc Device Boot Start End Blocks Id System /dev/sdc1 1 5 40131 83 Linux /dev/sdc2 6 1311 10490445 82 Linux swap / Solaris /dev/sdc3 1312 60801 477853425 83 Linux Disk /dev/md125: 489.3 GB, 489321791488 bytes 2 heads, 4 sectors/track, 119463328 cylinders Units = cylinders of 8 * 512 = 4096 bytes Disk identifier: 0x00000000 Disk /dev/md125 doesn't contain a valid partition table

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• svnstat script

  - by Kyle Hodgson

  So I'm building out a shell script to check out all of our relevant svn repositories for analysis in svnstat. I've gotten all of this to work manually, now I'm writing up a bash script in cygwin on my Vista laptop, as I intend to move this to a Linux server at some point. Edit: I gave up on this and wrote a simple .bat script. I'll figure out the Linux deployment some other way. Edit: added the sleep 30 and svn log commands. I can tell now, with the svn log command, that it's not getting to the svn log ... this time, it did Applications, and ran the log, and then check out Database, and froze. I'll put the sleep 30 before and after the log this time. co2.sh #!/bin/bash function checkout { mkdir $1 svn checkout svn://dev-server/$1 $1 svn log --verbose --xml >> svn.log $1 sleep 30 } cd /cygdrive/c/Users/My\ User/Documents/Repos/wc checkout Applications checkout Database checkout WebServer/www.mysite.com checkout WebServer/anotherhost.mysite.com checkout WebServer/AnotherApp checkout WebServer/thirdhost.mysite.com checkout WebServer/fourthhost.mysite.com checkout WebServer/WebServices It works, for the most part - but for some reason it has a tendency to stop working after a few repositories, usually right after finishing a repository before going to the next one. When it fails, it will not recover on its own. I've tried commenting out the svn line, it goes in and creates all the directories just fine when I do that - so its not that. I'm looking for direction as well as direct advice. Cygwin has been very stable for me, but I did start using the native rxvt instead of "bash in a cmd.exe window" recently. I don't think that's the problem, as I've left top on remote systems running all night and rxvt didn't seem to mind. Also I haven't done any bash scripting in cygwin so I suppose this might not be recommended; though I can't see why not. I don't want all of WebServer, hence me only checking out certain folders like that. What I suspect is that something is hanging up the svn checkout. Any ideas here? Edit: this time when I hit ctrl+z to cancel out, I forgot I was on Windows and typed ps to see if the job was still running; and as you can see there are lots of svn processes hanging around... strange. Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ jobs [1]- Stopped bash co2.sh [2]+ Stopped ./co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ kill %1 [1]- Stopped bash co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ [1]- Terminated bash co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ ps PID PPID PGID WINPID TTY UID STIME COMMAND 7872 1 7872 2340 0 1000 Jun 29 /usr/bin/svn 7752 1 6140 7828 1 1000 Jun 29 /usr/bin/svn 6192 1 5044 2192 1 1000 Jun 30 /usr/bin/svn 7292 1 7452 1796 1 1000 Jun 30 /usr/bin/svn 6236 1 7304 7468 2 1000 Jul 2 /usr/bin/svn 1564 1 5032 7144 2 1000 Jul 2 /usr/bin/svn 9072 1 3960 6276 3 1000 Jul 3 /usr/bin/svn 5876 1 5876 5876 con 1000 11:22:10 /usr/bin/rxvt 924 5876 924 10192 4 1000 11:22:10 /usr/bin/bash 7212 1 7332 5584 4 1000 13:17:54 /usr/bin/svn 9412 1 5480 8840 4 1000 15:38:16 /usr/bin/svn S 8128 924 8128 9452 4 1000 17:38:05 /usr/bin/bash 9132 8128 8128 8172 4 1000 17:43:25 /usr/bin/svn 3512 1 3512 3512 con 1000 17:43:50 /usr/bin/rxvt I 10200 3512 10200 6616 5 1000 17:43:51 /usr/bin/bash 9732 1 9732 9732 con 1000 17:45:55 /usr/bin/rxvt 3148 9732 3148 8976 6 1000 17:45:55 /usr/bin/bash 5856 3148 5856 876 6 1000 17:51:00 /usr/bin/vim 7736 924 7736 8036 4 1000 17:53:26 /usr/bin/ps Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ jobs [2]+ Stopped ./co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Here's an strace on the PID of the hung svn program, it's been like this for hours. Looks like its just doing nothing. I keep suspecting that some interruption on the server is causing this; does svn have a locking mechanism I'm not aware of? Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ strace -p 7304 ********************************************** Program name: C:\cygwin\bin\svn.exe (pid 7304, ppid 6408) App version: 1005.25, api: 0.156 DLL version: 1005.25, api: 0.156 DLL build: 2008-06-12 19:34 OS version: Windows NT-6.0 Heap size: 402653184 Date/Time: 2009-07-06 18:20:11 **********************************************

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• How do you handle authentication across domains?

  - by William Ratcliff

  I'm trying to save users of our services from having to have multiple accounts/passwords. I'm in a large organization and there's one group that handles part of user authentication for users who are from outside the facility (primarily for administrative functions). They store a secure cookie to establish a session and communicate only via HTTPS via the browser. Sessions expire either through: 1) explicit logout of the user 2) Inactivity 3) Browser closes My team is trying to write a web application to help users analyze data that they've taken (or are currently taking) while at our facility. We need to determine if a user is 1) authenticated 2) Some identifier for that user so we can store state for them (what analysis they are working on, etc.) So, the problem is how do you authenticate across domains (the authentication server for the other application lives in a border region between public and private--we will live in the public region). We have come up with some scenarios and I'd like advice about what is best practice, or if there is one we haven't considered. Let's start with the case where the user is authenticated with the authentication server. 1) The authentication server leaves a public cookie in the browser with their primary key for a user. If this is deemed sensitive, they encrypt it on their server and we have the key to decrypt it on our server. When the user visits our site, we check for this public cookie. We extract the user_id and use a public api for the authentication server to request if the user is logged in. If they are, they send us a response with: response={ userid :we can then map this to our own user ids. If necessary, we can request additional information such as email-address/display name once (to notify them if long running jobs are done, or to share results with other people, like with google_docs). account_is_active:Make sure that the account is still valid session_is_active: Is their session still active? If we query this for a valid user, this will have a side effect that we will reset the last_time_session_activated value and thus prolong their session with the authentication server last_time_session_activated: let us know how much time they have left ip_address_session_started_from:make sure the person at our site is coming from the same ip as they started the session at } Given this response, we either accept them as authenticated and move on with our app, or redirect them to the login page for the authentication server (question: if we give an encrypted portion of the response (signed by us) with the page to redirect them to, do we open any gaping security holes in the authentication server)? The flaw that we've found with this is that if the user visits evilsite.com and they look at the session cookie and send a query to the public api of the authentication server, they can keep the session alive and if our original user leaves the machine without logging out, then the next user will be able to access their session (this was possible before, but having the session alive eternally makes this worse). 2) The authentication server redirects all requests made to our domain to us and we send responses back through them to the user. Essentially, they act as a proxy. The advantage of this is that we can handshake with the authentication server, so it's safe to be trusted with the email address/name of the user and they don't have to reenter it So, if the user tries to go to: authentication_site/mysite_page1 they are redirected to mysite. Which would you choose, or is there a better way? The goal is to minimize the "Yet Another Password/Yet another username" problem... Thanks!!!!

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• creating a heirarchy of terminals or workspaces

  - by intuited

  <rant This question occurred to me ('occurred' meaning 'whispered seductively in my ear for the 100th time') while using GNU-screen, so I'll make that my example. However this is a much more general question about user interfaces and what I perceive as a flawmissing feature in every implementation I've yet seen. I'm wondering if there is some way to create a heirarchy/tree of terminals in a screen session. EG I'd like to have something like 1 bash 1.1 bash 1.2 bash 2 bash 3 bash 3.1 bash 3.1.1 bash 3.1.2 bash It would be good if the terminals could be labelled instead of having to be navigated to via some arrangement that I suspect doesn't exist. So then you could jump to one using eg ^A:goto happydays or ^A:goto dykstra.angry. So to generalize that: Firefox, Chrome, Internet Explorer, gnome-terminal, roxterm, konsole, yakuake, OpenOffice, Microsoft Office, Mr. Snuffaluppagus's Funtime Carousel™, and Your Mom's Jam Browser™ all offer the ability to create a flat set of tabs containing documents of an identical nature: web pages, terminals, documents, fun rideable animals, and jams. GNU-screen implements the same functionality without using tabs. Linux and OS/X window managers provide the ability to organize windows into an array of workspaces, which amounts to again, the same deal. Over the past few years, this has become a more or less ubiquitous concept which has been righteously welcomed into the far reaches of the computer interface funfest. Heavy users of these systems quickly encounter a problem with it: the set of entities is flat. In the case of workspaces, an option may be available to create a 2d array. However none of these applications furnish their users with the ability to create heirarchies, similar to filesystem directory structures, containing instances of their particular contained type. I for one am consistently bothered by this, and am wondering if the community can offer some wisdom as to why this has not happened in any of the foremost collections of computational functionality our culture has yet produced. Or if perhaps it has and I'm just an ignorant savage. I'd like to be able to not only group things into a tree structure, but also to create references (aka symbolic links, aka pointers) from one part of the structure to another, as well as apply properties (eg default directory, colorscheme, ...) recursively downward from a given node. I see no reason why we shouldn't be able to save these structures as known sessions, and apply tags to particular instances. So then you can sort through them by tag, find them by name, or just use the arrow keys (with an appropriate modifier) to move left or right and in or out of a given level. Another key combo would serve to create a branch in the place of the current terminal/webpage/lifelike statue/spreadsheet/spreadsheet sheet/presentation/jam and move that entity into the new branch, then create a fresh one as a sibling to it: a second leaf node within the same branch node. They would get along well. I find it a bit astonishing that this hasn't happened yet, and the only reason I can venture as a guess is that the creators of these fine systems do not consider such functionality to be useful to a significant portion of their userbase. I posit that the probability that that such an assumption would be correct is pretty low. On the other hand, given the relative ease with which such structures can be implemented using modern libraries/languages, it doesn't seem likely that difficulty of implementation would be a major roadblock. If it could be done in 1972 or whenever within the constraints of a filesystem driver, it should be relatively painless to implement in 2010 in a fullblown application. Given that all of these systems are capable of maintaining a set of equivalent entities, it seems unlikely that a major infrastructure overhaul would be necessary in order to enable a navigable heirarchy of them. </rant Mostly I'm just looking to start up a discussion and/or brainstorming on this topic. Any ideas, examples, criticism, or analysis are quite welcome. * Mr. Snuffaluppagus's Funtime Carousel is a registered trademark of Children's Television Workshop Inc. * Your Mom's Jam Browser is a registered trademark of Your Mom Inc.

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• How to block subreddits with BIND9?

  - by user1391189

  Please help me block NSFW subreddits like this one (http://www.reddit.com/r/NSFW/) I would like to keep access to SFW subreddits, but block certain subreddits that are distracting or NSFW. I know how to filter domains. (see files below) But how do I apply the filter only to certain subreddits? So far I have set up the following files: blocklist.conf zone "adimages.go.com" { type master; file "dummy-block"; }; zone "admonitor.net" { type master; file "dummy-block"; }; zone "ads.specificpop.com" { type master; file "dummy-block"; }; ... named.conf options { allow-query { 127.0.0.1; }; allow-recursion { 127.0.0.1; }; directory "c:\bind\etc"; notify no; }; zone "." IN { type hint; file "c:\bind\etc\named.root"; }; zone "localhost" IN { allow-update { none; }; file "c:\bind\etc\localhost.zone"; type master; }; zone "0.0.127.in-addr.arpa" IN { allow-update { none; }; file "c:\bind\etc\named.local"; type master; }; key "rndc-key" { algorithm hmac-md5; secret "O5VdbBKKEMzuLYjM60CxwuLLURFA6peDYHCBvZCqjoa6KtL1ggD7OTLeLtnu2jR5I5cwA/MQ8UdHc+9tMJRSiw=="; }; controls { inet 127.0.0.1 port 953 allow { 127.0.0.1; } keys { "rndc-key"; }; }; //Blocklist include "c:\bind\etc\blocklist.conf"; dummy-block $TTL 604800 @ IN SOA localhost. root.localhost. ( 2 ; Serial 604800 ; Refresh 86400 ; Retry 2419200 ; Expire 604800 ) ; Negative Cache TTL ; @ IN NS localhost. @ IN A 127.0.0.1 * IN A 127.0.0.1

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• Why is site serving different SSL certs to different browsers?

  - by TRiG

  The SSL certificate on menswearireland.com and on www.menswearireland.com works fine on Safari, Chrome, SeaMonkey, K-Meleon, QtWeb, Firefox, and Opera. However, Internet Explorer claims that there is an error: The security certificate presented by this website was not issued by a trusted certificate authority. The security certificate presented by this website was issued for a different website's address. Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server. Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0) Another site hosted on the same managed server shows no errors: achill-fieldschool.com and www.achill-fieldschool.com work fine on IE, even though as far as I can tell the certificate is set up identically. What am I doing wrong? This is a LAMPP server running Plesk. It looks like the server is showing different certificates to different clients. To some clients it shows a RapidSSL certificate made out to www.menswearireland.com with menswearireland.com as a valid alternative name. To other clients, it shows a Parallels Panel certificate, made out to Parallels Panel. Here are results from a few different online SSL checkers: most say it's fine, while two show errors. Three online checkers say it's valid Comodo SSL Check shows it as valid DigiCert SSL Check shows it as valid SSL Shopper SSL Check shows it as valid Common name: www.menswearireland.com SANs: www.menswearireland.com, menswearireland.com Valid from October 2, 2012 to November 4, 2013 Serial Number: 559425 (0x88941) Signature Algorithm: sha1WithRSAEncryption Issuer: RapidSSL CA Another online checker seems to see a completely different certificate GeoCerts SSL Check shows it as invalid Common name: Parallels Panel Organization: Parallels Valid from August 15, 2012 to August 15, 2013 Issuer: Parallels Panel Another online checker sees more than one certificate Symantic SSL Check shows it as invalid The certificate installation checker connected to the Web server and read its certificates, but could not determine which is the primary certificate for the Web server. Incidentally, on both menswearireland.com and achill-fieldschool.com the homepage will redirect from HTTPS to HTTP. To see SSL details, visit the page /account on both (that page will redirect from HTTP to HTTPS). I’ve found more information in a more detailed online SSL checker. https://www.ssllabs.com/ssltest/analyze.html?d=menswearireland.com This site works only in browsers with SNI support My understanding is that SNI (RFC 6066) is a method for putting many SSL sites on one shared IP address and port. This does not work on Internet Explorer on older versions of Windows (this has to do with the version of Windows, not the version of Internet Explorer). However, all our SSL sites are on a unique IP address, so we shouldn’t need SNI.

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