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• Are there any radix/patricia/critbit trees for Python?

  - by Andrew Dalke

  I have about 10,000 words used as a set of inverted indices to about 500,000 documents. Both are normalized so the index is a mapping of integers (word id) to a set of integers (ids of documents which contain the word). My prototype uses Python's set as the obvious data type. When I do a search for a document I find the list of N search words and their corresponding N sets. I want to return the set of documents in the intersection of those N sets. Python's "intersect" method is implemented as a pairwise reduction. I think I can do better with a parallel search of sorted sets, so long as the library offers a fast way to get the next entry after i. I've been looking for something like that for some time. Years ago I wrote PyJudy but I no longer maintain it and I know how much work it would take to get it to a stage where I'm comfortable with it again. I would rather use someone else's well-tested code, and I would like one which supports fast serialization/deserialization. I can't find any, or at least not any with Python bindings. There is avltree which does what I want, but since even the pair-wise set merge take longer than I want, I suspect I want to have all my operations done in C/C++. Do you know of any radix/patricia/critbit tree libraries written as C/C++ extensions for Python? Failing that, what is the most appropriate library which I should wrap? The Judy Array site hasn't been updated in 6 years, with 1.0.5 released in May 2007. (Although it does build cleanly so perhaps It Just Works.)

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• FlashBuilder 4 and Zend Framework error

  - by sig

  I am trying to use adobe flash builder 4 with a php service. I had it set up an older macbook running leopard, but just tried to set it up on my new laptop running snow leopard. I did all the same steps.. set the Flex Server to be PHP, set the web root and url. Then I go to Data-Connect To PHP and point it to a php file I have in my web root. It says it needs to install Zend, and claims it does so successfully, but then when I try to continue, I get an error. I don't understand.. this same setup works on my older laptop. (Yes, I checked the amf.production was false) Unable to retrieve operations and entities from the file Make sure that Zend Framework is installed correctly and the parameter "amf.production" is not set to true in the amf_config.ini file located in the project output folder. false), true);$default_config-merge(new Zend_Config_Ini($configfile, 'zendamf'));$default_config-setReadOnly();$amf = $default_config-amf;// Store configuration in the registryZend_Registry::set("amf-config", $amf);// Initialize AMF Server$server = new Zend_Amf_Server();$server-setProduction($amf-production);if(isset($amf-directories)) { $dirs = $amf-directories-toArray(); foreach($dirs as $dir) { // get the first character of the path. // If it does not start with slash then it implies that the path is relative to webroot. Else it will be treated as absolute path $length = strlen($dir); $firstChar = $dir; if($length = 1) $firstChar = $dir[0]; if($firstChar != "/"){ // if the directory is ./ path then we add the webroot only. if($dir == "./"){ $server-addDirectory($webroot); }else{ $tempPath = $webroot . "/" . $dir; $server-addDirectory($tempPath); } }else{ $server-addDirectory($dir); } }}// Initialize introspector for non-productionif(!$amf-production) { $server-setClass('Zend_Amf_Adobe_Introspector', '', array("config" = $default_config, "server" = $server)); $server-setClass('Zend_Amf_Adobe_DbInspector', '', array("config" = $default_config, "server" = $server));}// Handle requestecho $server-handle();

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• SQLite on iPhone - Techniques for tracking down multithreading-related bugs

  - by Jasarien

  Hey guys, I'm working with an Objective-C wrapper around SQLite that I didn't write, and documentation is sparse... It's not FMDB. The people writing this wrapper weren't aware of FMDB when writing this code. It seems that the code is suffering from a bug where database connections are being accessed from multiple threads -- which according to the SQLite documentation won't work if the if SQLite is compiled with SQLITE_THREADSAFE 2. I have tested the libsqlite3.dylib provided as part of the iPhone SDK and seen that it is compiled in this manner, using the sqlite_threadsafe() routine. Using the provided sqlite library, the code regularly hits SQLITE_BUSY and SQLITE_LOCKED return codes when performing routines. To combat this, I added some code to wait a couple of milliseconds and try again, with a maximum retry count of 50. The code didn't contain any retry logic prior to this. Now when a sqlite call returns SQLITE_BUSY or SQLITE_LOCKED, the retry loop is invoked and the retry returns SQLITE_MISUSE. Not good. Grasping at straws, I replaced the provided sqlite library with a version compiled by myself setting SQLITE_THREADSAFE to 1 - which according to the documentation means sqlite is safe to be used in a multithreaded environment, effectively serialising all of the operations. It incurs a performance hit, that which I haven't measured, but it ridded the app of the SQLITE_MISUSE happening and seemed to not need the retry logic as it never hit a busy or locked state. What I would rather do is fix the problem of accessing a single db connection from multiple threads, but I can't for the life of me find where it's occurring. So if anyone has any tips on locating multithreaded bugs I would be extremely appreciative. Thanks in advance.

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• Passing custom Python objects to nosetests

  - by Rob

  I am attempting to re-organize our test libraries for automation and nose seems really promising. My question is, what is the best strategy for passing Python objects into nose tests? Our tests are organized in a testlib with a bunch of modules that exercise different types of request operations. Something like this: testlib \-testmoda \-testmodb \-testmodc In some cases the test modules (i.e. testmoda) is nothing but test_something(), test_something2() functions while in some cases we have a TestModB class in testmob with the test_anotherthing1(), test_anotherthing2() functions. The cool thing is that nose easily finds both. Most of those test functions are request factory stuff that can easily share a single connection to our server farm. Thus we do a lot of test_something1(cnn), TestModB.test_anotherthing2(cnn), etc. Currently we don't use nose, instead we have a hodge-podge of homegrown driver scripts with hard-coded lists of tests to execute. Each of those driver scripts creates its own connection object. Maintaining those scripts and the connection minutia is painful. I'd like to take free advantage of nose's beautiful discovery functionality, passing in a connection object of my choosing. Thanks in advance! Rob P.S. The connection objects are not pickle-able. :(

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• Why do people hate SQL cursors so much?

  - by Steven A. Lowe

  I can understand wanting to avoid having to use a cursor due to the overhead and inconvenience, but it looks like there's some serious cursor-phobia-mania going on where people are going to great lengths to avoid having to use one for example, one question asked how to do something obviously trivial with a cursor and the accepted answer proposed using a common table expression (CTE) recursive query with a recursive custom function, even though this limits the number of rows that could be processed to 32 (due to recursive call limit in sql server). This strikes me as a terrible solution for system longevity, not to mention a tremendous effort just to avoid using a simple cursor. what is the reason for this level of insane hatred? has some 'noted authority' issued a fatwa against cursors? does some unspeakable evil lurk in the heart of cursors that corrupts the morals of the children or something? wiki question, more interested in the answer than the rep thanks in advance! Related Info: http://stackoverflow.com/questions/37029/sql-server-fast-forward-cursors EDIT: let me be more precise: I understand that cursors should not be used instead of normal relational operations, that is a no-brainer. What I don't understand is people going waaaaay out of their way to avoid cursors like they have cooties or something, even when a cursor is a simpler and/or more efficient solution. It's the irrational hatred that baffles me, not the obvious technical efficiencies.

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• How to best show progress info when using ADO.NET?

  - by Yadyn

  I want to show the user detailed progress information when performing potentially lengthy database operations. Specifically, when inserting/updating data that may be on the order of hundreds of KB or MB. Currently, I'm using in-memory DataTables and DataRows which are then synced with the database via TableAdapter.Update calls. This works fine and dandy, but the single call leaves little opportunity to glean any kind of progress info to show to the user. I have no idea how much data is passing through the network to the remote DB or its progress. Basically, all I know is when Update returns and it is assumed complete (barring any errors or exceptions). But this means all I can show is 0% and then a pause and then 100%. I can count the number of rows, even going so far to cound how many are actually Modified or Added, and I could even maybe calculate per DataRow its estimated size based on the datatype of each column, using sizeof for value types like int and checking length for things like strings or byte arrays. With that, I could probably determine, before updating, an estimated total transfer size, but I'm still stuck without any progress info once Update is called on the TableAdapter. Am I stuck just using an indeterminate progress bar or mouse waiting cursor? Would I need to radically change our data access layer to be able to hook into this kind of information? Even if I can't get it down to the precise KB transferred (like a web browser file download progress bar), could I at least know when each DataRow/DataTable finishes or something? How do you best show this kind of progress info using ADO.NET?

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• NSMutableURLRequest wont turn on 3G

  - by Kyle

  I won't bother posting any code because my code works fine when I launch Safari or something that turns on the 3G connection first. When I put it Airport mode, then put back OFF, I will get the behavior of a connection error saying No internet connection with NSMutableURLRequest. I've personally mailed apple about how the Ant gets turned on and off, and they said anything that uses their base CFSocketStream object will turn on the Ant, and I quote: "such as NSURLRequest".. BSD Sockets do not, just so everyone knows.. However, I assumed NSMutableURLRequest would fall into the category of 'Does', but it seems like it doesnt. It never succeeds for me when I cycle Airport or have the phone idle for a long time. It will ALWAYS succeed when I open any other network app first to turn the Ant on. Shall I be forced to do a dummy NSURLRequest call to turn this on; or has anyone been able to get this class working just fine? Remember this is just an implementation of NSMutableURLRequest to upload a file Async, and no other Network operations are performed anywhere; no ads, no version checks, no nothing.

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• how to implement login and service features as in skype or msn chat in a wpf application

  - by black sensei

  Hello Good people! I'm building an WPF application that connect to web services for its operations.Things that i needed to be working are so far fine.Now i'll like to improve use experience by adding features like username editable combobox, sign me in when skype start and start when computer start. I have a fair idea about each feature but very small knowledge about their implementation. Question 1 username combobox : i use a combobox with isEditable set to true but i think it doesnt have the previous username, would that mean that i have to store every successful login username in a sqlite for example? Question 2 sign me in when skype start : i think about using sqlite after all to store the credentials and store the value (as in true or false) if autologin has to be performed. Question 3 start when computer start : i know it's about having is as service.but the process of using it as a service and removing its service when checkbox is checked or unckecked is a bit confusing to me. Question 4 Please wait(signing in) of skype if i want to do things like please wait at login(login is over webservice) in a WPF application should i use a animated gif in a grid that i can show when hiding the login combobox and passwordbox grid or i should use an animated object(for which i have no knowledge about for now) ? This post in mainly for you experts to either point me to the right resource and tell me what is done as best practice. things like dos and dons.Thanks for reading this and please let me have a clair idea about how to start implementing those features. thanks again

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• How do I implement repository pattern and unit of work when dealing with multiple data stores?

  - by Jason

  I have a unique situation where I am building a DDD based system that needs to access both Active Directory and a SQL database as persistence. Initially this wasnt a problem because our design was setup where we had a unit of work that looked like this: public interface IUnitOfWork { void BeginTransaction() void Commit() } and our repositories looked like this: public interface IRepository<T> { T GetByID() void Save(T entity) void Delete(T entity) } In this setup our load and save would handle the mapping between both data stores because we wrote it ourselves. The unit of work would handle transactions and would contain the Linq To SQL data context that the repositories would use for persistence. The active directory part was handled by a domain service implemented in infrastructure and consumed by the repositories in each Save() method. Save() was responsible with interacting with the data context to do all the database operations. Now we are trying to adapt it to entity framework and take advantage of POCO. Ideally we would not need the Save() method because the domain objects are being tracked by the object context and we would just need to add a Save() method on the unit of work to have the object context save the changes, and a way to register new objects with the context. The new proposed design looks more like this: public interface IUnitOfWork { void BeginTransaction() void Save() void Commit() } public interface IRepository<T> { T GetByID() void Add(T entity) void Delete(T entity) } This solves the data access problem with entity framework, but does not solve the problem with our active directory integration. Before, it was in the Save() method on the repository, but now it has no home. The unit of work knows nothing other than the entity framework data context. Where should this logic go? I argue this design only works if you only have one data store using entity framework. Any ideas how to best approach this issue? Where should I put this logic?

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• C question: error: expected ')' before '*' token

  - by lhw

  ===EDIT I apologize for not putting the pcb struct into the code snippet. There is a struct called pcb defined in above the two structs I originally posted. Namely, typedef struct{ UINT32 proc; struct pcb *link; }pcb; Hi, I asked a question regarding structs in C a few minutes ago and got an answer blazing fast. But now I'm facing another problem, namely the error in the title of this question. I'm trying to implement a simple priority queue in C using arrays of queues. However, when I try to declare a function on pcb_pQ structure, I get the above error. I have the structs clearly defined in the heard file. In the header file: typedef struct{ pcb *head; pcb *tail; SINT32 size; } pcb_Q; typedef struct pcb_pQ { pcb_Q queues[5]; SINT32 size; } pcb_pQ; Function prototype in header file: /*priority queue operations*/ VOID pcb_pq_enqueue(pcb_pQ*, pcb*); Function impelmentation in .c file: VOID pcb_pq_enqueue(pcb_pQ* pcb_pQ, pcb* pcb) { pcb_Q* pcb_Q_p; int priority; priority = pcb->proc_priority; pcb_Q_p = &pcb_pQ->queues[priority]; pcb_enqueue(pcb_Q_p, pcb); } When I try to compile the above code, I get an "error: expected ')' before '*' token". This error is pointing to the function signature in the .c file, namely VOID pcb_pq_enqueue(pcb_pQ* pcb_pQ, pcb* pcb) { But I am not sure why I am getting this error, could someone give me a hand? Thanks a lot.

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• Getting svn: E170000: Unrecognized URL scheme for my custom Svn Gradle plugin

  - by Ip Doh

  I wrote a custom gradle plugin using groovy to do basic svn tasks like, Checkout, Clean, Tag etc. The groovy class calls the svn command line client to do these operations, It works fine when i run it on my windows system but the same plugin gives the following error when i run it on a linux system (Centos). svn: E170000: Unrecognized URL scheme for '%22https://source.mycompany.net/svn/MyProject/trunk%22' Am able to make the same calls to the command line client through the command prompt or shell script without any issues. So what is the difference with Here is my code sample String command =String.format("svn co -r %d --non-interactive --trust-server-cert -- username %s --password %s --depth infinity \"%s\" \"%s\"", getRevision(), getUserName(), getUserPassword(), getSrcUrl(), getDir()); Process svnProcess = Runtime.getRuntime().exec(command); BufferedReader stdInput = new BufferedReader(new InputStreamReader(svnProcess.getInputStream())); BufferedReader stdError = new BufferedReader(new InputStreamReader(svnProcess.getErrorStream())); String statusOutputLine ="" while ((statusOutputLine = stdInput.readLine()) != null) { logger.quiet(" " + statusOutputLine); } while (( statusOutputLine = stdError.readLine()) != null) { logger.error(statusOutputLine) throw new Exception(statusOutputLine) } logger.quiet("Successfully Checked out the work space") i do have neon installed on the system -bash-4.1$ svn --version svn, version 1.6.11 (r934486) compiled Jun 25 2011, 11:30:15 Copyright (C) 2000-2009 CollabNet. Subversion is open source software, see http://subversion.tigris.org/ This product includes software developed by CollabNet (http://www.Collab.Net/). The following repository access (RA) modules are available: ra_neon : Module for accessing a repository via WebDAV protocol using Neon. handles 'http' scheme handles 'https' scheme ra_svn : Module for accessing a repository using the svn network protocol. with Cyrus SASL authentication handles 'svn' scheme ra_local : Module for accessing a repository on local disk. handles 'file' scheme

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• Grouped UITableView Footer Sometimes Hidden On Quick Scroll

  - by jdandrea

  OK, this one is a puzzler. There is one similar post but it's not similar enough to count, so I'm posting this one. :) I've got a grouped UITableView with a header and footer. The footer includes two UIButton views, side-by-side. Nothing major. Now … there is a toggle button in a UIToolbar at the bottom for more/less info in this table view. So I build my index paths to delete/insert with fade row animation, all the usual ingredients, sandwiched between beginUpdates and endUpdates calls on the UITableView … and this works fine! In also happens that my footer can sometimes be pushed off past the bottom of the display. Here's where it gets weird. If I drag my finger up the display, scrolling the view upward, I should see that footer eventually, right? Well … most of the time I do. BUT, if I flick my finger up, for a faster scroll, the footer is missing. Even if you try to tap in that area - no response. However, if I scroll back down again, just to hide that footer (or rather hide the area where the footer would normally be), and then scroll back up, it's there once again! This only happens when inserting rows. If I delete rows, the footer stays put … unless of course it was already hidden and I didn't perform the aforementioned incantation to get it back. :) I am trying to trace through this, but to no avail. I suppose tracing through scroll operations is a bit of a crazy proposition! Perhaps some creative logging … suggestions, anyone? Or is this a known issue in 3.1 where row insert/deletes are concerned? (I don't recall seeing it until 3.1.)

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• What's the largest (most complex) PHP algorithm ever implemented in a single monolithic PHP script?

  - by Alex R

  I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The source needs to be in a single file. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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• How to estimate size of data to transfer when using DbCommand.ExecuteXXX?

  - by Yadyn

  I want to show the user detailed progress information when performing potentially lengthy database operations. Specifically, when inserting/updating data that may be on the order of hundreds of KB or MB. Currently, I'm using in-memory DataTables and DataRows which are then synced with the database via TableAdapter.Update calls. This works fine and dandy, but the single call leaves little opportunity to glean any kind of progress info to show to the user. I have no idea how much data is passing through the network to the remote DB or its progress. Basically, all I know is when Update returns and it is assumed complete (barring any errors or exceptions). But this means all I can show is 0% and then a pause and then 100%. I can count the number of rows, even going so far to cound how many are actually Modified or Added, and I could even maybe calculate per DataRow its estimated size based on the datatype of each column, using sizeof for value types like int and checking length for things like strings or byte arrays. With that, I could probably determine, before updating, an estimated total transfer size, but I'm still stuck without any progress info once Update is called on the TableAdapter. Am I stuck just using an indeterminate progress bar or mouse waiting cursor? Would I need to radically change our data access layer to be able to hook into this kind of information? Even if I can't get it down to the precise KB transferred (like a web browser file download progress bar), could I at least know when each DataRow/DataTable finishes or something? How do you best show this kind of progress info using ADO.NET?

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• Appending data to NSFetchedResultsController during find or create loop

  - by Justin Williams

  I have a table view that is managed by an NSFetchedResultsController. I am having an issue with a find-or-create operation, however. When the user hits the bottom of my table view, I am querying my server for another batch of content. If it doesn't exist in the local cache, we create it and store it. If it does exist, however, I want to append that data to the fetched results controller and display it. I can't quite figure that part out. Here's what I'm doing thus far: Passing the returned array of values from my server to an NSOperation to process. In the operation, create a new managed object context to work with. In the operation, I iterate through the array and execute a fetch request to see if the object exists (based on its server id). If the object doesn't exist, we create it and insert it into the operations' managed object context. After the iteration completes, we save the managed object context, which triggers a merge notification on my main thread. At this point, any objects that weren't locally cached in my Core Data store before will appear, but the ones that previously existed do not come along for the ride. I feel like it's something simple I'm missing, and could use a nudge in the right direction.

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• Status Code from FTPWebRequest GetResponse method

  - by nick

  This is slightly tricky. I am uploading files to FTP asynchronously. After uploading each file I am checking the status of the upload operation for that file. This can be done with StatusCode property of the FtpWebResponse object for that request. The code snippet is as give below. System.IO.FileStream fs = System.IO.File.Open(fileName, System.IO.FileMode.Open); while ((iWork = fs.Read(buf, 0, buf.Length)) > 0) requestStream.Write(buf, 0, iWork); requestStream.Close(); FtpWebResponse wrRet = ((FtpWebResponse)state.Request.GetResponse()); There are about 37 StatusCode values as per msdn. I am unaware as to which of these status code values will assure that the file is uploaded successfully. Some of them I used in my code to check for success are : wrRet.StatusCode == FtpStatusCode.CommandOK wrRet.StatusCode == FtpStatusCode.ClosingData wrRet.StatusCode == FtpStatusCode.ClosingControl wrRet.StatusCode == FtpStatusCode.ConnectionClosed wrRet.StatusCode == FtpStatusCode.FileActionOK wrRet.StatusCode == FtpStatusCode.FileStatus But I am unaware of the rest. I need to be sure about these codes because based on the failure or success of the upload operation I have other dependant operations to be carried out. A wrong condition can affect the remaining code. Another thought that crossed my mind was to simply put the above code into a try..catch and not depend on these status codes. With this I would not be depending on the status codes and assuming that any failure will always be directed to the catch block. Kindly let me know if this is the right way. Thanks in advance.

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• Getting parameters values blank and null when using custom wsdl in axis2

  - by Narendra

  Hi All, I am using axis2 for my web services creation. I want to user my own wsdl file instead of using generated wsdl file. When I am placing my own wsdl file in META-INF directory and deploying my web services they are deploying successfully. But the problem is when i try to test these web service using soapui it throwing null pointer exception. For example I am invoking following operations in soap ui. public String testWebService(String a, String b) { LogHelper.info("Value of a is:"+a); LogHelper.info("Value of b is :"+b); String c=a.trim()+b.Trim(); return "suceess" } output in console: value of a is: value of b is:null 19:58:47,781 ERROR [RPCMessageReceiver] Exception occurred while trying to invoke service method testWebService java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.axis2.rpc.receivers.RPCUtil.invokeServiceClass(RPCUtil.java:194) at org.apache.axis2.rpc.receivers.RPCMessageReceiver.invokeBusinessLogic(RPCMessageReceiver.java:102) at org.apache.axis2.receivers.AbstractInOutMessageReceiver.invokeBusinessLogic(AbstractInOutMessageReceiver.java:40) at org.apache.axis2.receivers.AbstractMessageReceiver.receive(AbstractMessageReceiver.java:114) at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:173) at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:173) at org.apache.axis2.transport.http.AxisServlet.doPost(AxisServlet.java:142) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92) at o...................................................... SO What i understand is i am getting value for a is black and value of b is null. Can any one give me any suggestions please. Thanks, Narendra

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• How to improve Java performance on Informix for Windows

  - by Michal Niklas

  I have problem with performance of Java UDR functions on Informix on Windows. On this server I already have some functions in C and SPL. I chose one function to write it in those 3 languages and I measured performance of this function on test table. Function calculates some kind of checksum so it does not use any db libraries etc. only string and math operations. I observed performance on 30k records with SQL like: select function(txt) from _tmp_perf_test and I changed function to 'function_c, function_spl or function_java. My performance tests showed that C function is the fastest, SPL function is about 5 times slower, where Java is 100 (one hundred!) times slower than C. I checked it few times and 1:100 ratio didn't improve. I changed Java function to simply return length of the string but even this do not help so it looks, that there is general problem with Java function invocation, because there was no difference in time between Java function that calculate checksum and Java function that returns length of the string. I increased JVM_MAX_HEAP_SIZE to 128 and it not helped too. I use IBM Informix Dynamic Server Version 11.50.TC6DE. The same test on Linux server: IBM Informix Dynamic Server Version 11.50.FC6 show more "normal" results, i.e. Java is slower from C and SPL but only 2 to 5 times. What can I do to improve Java performance on Informix server on Windows? More info about Java on servers: c:\Informix\extend\krakatoa\jre\bin>java -version java version "1.5.0" Java(TM) 2 Runtime Environment, Standard Edition (build pwi32dev-20081129a (SR9-0 )) IBM J9 VM (build 2.3, J2RE 1.5.0 IBM J9 2.3 Windows Server 2003 x86-32 j9vmwi3223-20081129 (JIT enabled) J9VM - 20081126_26240_lHdSMr JIT - 20081112_1511ifx1_r8 GC - 200811_07) JCL - 20081129 [root@informix11 bin]# ./java -version java version "1.5.0" Java(TM) 2 Runtime Environment, Standard Edition (build pxa64devifx-20071025 (SR6b)) IBM J9 VM (build 2.3, J2RE 1.5.0 IBM J9 2.3 Linux amd64-64 j9vmxa6423-20071005 (JIT enabled) J9VM - 20071004_14218_LHdSMr JIT - 20070820_1846ifx1_r8 GC - 200708_10) JCL - 20071025

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• using Autofac in a multi-layered architecture

  - by Kamyar

  I'm fairly new to the DI/IoC concept and would like to use Autofac in a 3-layered ASP.NET Webforms application. UI layer: An ASP.NET webforms website. BLL: Business logic layer which calls the repositories on DAL. DAL: .EDMX file (Entity Model) and ObjectContext with Repository classes which abstract the CRUD operations for each entity. Entities: The POCO Entities. Persistence Ignorant. Generated by Microsoft's ADO.Net POCO Entity Generator. I have asked a more general question here. Basically, I'd like to create an obejctcontext per HttpContext in my DAL. But i don't want to add a reference to DAL in UI or access to HttpContext in DAL directly. I guess this is where IoC tools come to play. The answer to my previous question is a very good example of using Windsor Castle. I'd like to use Autofac as my IoC tool and Don't know how to achieve this. (How to access DAL in application_start to register the component while I don't want to reference it in my UI, what are the proper references to be able to use DAL component in BLL with Autofac, Should I register BLL as a component with Autofac too) Sorry folks for not providing an explicit question and requesting a kind of working example, But I'm very unfamiliar to the whole IoC concept and I don't think I can achieve it to use in my current time-limited project.

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• Pair-wise iteration in C# or sliding window enumerator

  - by f3lix

  If I have an IEnumerable like: string[] items = new string[] { "a", "b", "c", "d" }; I would like to loop thru all the pairs of consecutive items (sliding window of size 2). Which would be ("a","b"), ("b", "c"), ("c", "d") My solution was is this public static IEnumerable<Pair<T, T>> Pairs(IEnumerable<T> enumerable) { IEnumerator<T> e = enumerable.GetEnumerator(); e.MoveNext(); T current = e.Current; while ( e.MoveNext() ) { T next = e.Current; yield return new Pair<T, T>(current, next); current = next; } } // used like this : foreach (Pair<String,String> pair in IterTools<String>.Pairs(items)) { System.Out.PrintLine("{0}, {1}", pair.First, pair.Second) } When I wrote this code, I wondered if there are already functions in the .NET framework that do the same thing and do it not just for pairs but for any size tuples. IMHO there should be a nice way to do this kind of sliding window operations. I use C# 2.0 and I can imagine that with C# 3.0 (w/ LINQ) there are more (and nicer) ways to do this, but I'm primarily interested in C# 2.0 solutions. Though, I will also appreciate C# 3.0 solutions.

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• Rotating an object in OpenGL ES for iPhone [translate to origin --> rotate --> translate back is not

  - by ayanonagon

  I recently started working with OpenGL ES for the iPhone, and I am having a bit of trouble with it. I want to be able to rotate an object with your fingers. My problem is that I have my object placed at (0, 0, -3), and I would like to rotate it about its center. I know that I need to translate back to the origin, rotate, and then bring it back to the original place. I think I am facing a problem because I am using a matrix to keep track (?) of all of my rotations/translation/scaling etc, and I think it may be combining the operations in a way that order is not even considered (so the two translations would cancel each other). I just started learning OpenGL a day ago and am a complete newbie, so my assumption may be wrong. Here is the part of the in drawView that I am having trouble with: GLfloat matrix[16]; glGetFloatv(GL_MODELVIEW_MATRIX, matrix); glLoadIdentity(); glTranslatef(0, 0, 3); // bring to origin glRotatef(self.angle, self.dy, self.dx, 0); // rotate glTranslatef(0, 0, -3); // put it back in place glMultMatrixf(matrix); // save the transformations performed Help would be much appreciated, thank you!

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• Is there a PHP benchmark that meets these specific criteria? [closed]

  - by Alex R

  I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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• Merging: hg/git vs. svn

  - by stmax

  I often read that hg (and git and...) are better at merging than svn but I have never seen practical examples of where hg/git can merge something where svn fails (or where svn needs manual intervention). Could you post a few step-by-step lists of branch/modify/commit/...-operations that show where svn would fail while hg/git happily moves on? Practical, not highly exceptional cases please... Some background: we have a few dozen developers working on projects using svn, with each project (or group of similar projects) in its own repo. We know how to apply release- and feature-branches so we don't run into problems very often (i.e. we've been there, but we've learned to overcome joel's problems of "one programmer causing trauma to the whole team" or "needing six developers for two weeks to reintegrate a branch"). We have release-branches that are very stable and only used to apply bugfixes. We have trunks that should be stable enough to be able to create a release within one week. And we have feature-branches that single developers or groups of developers can work on. Yes, they are deleted after reintegration so they don't clutter up the repository. ;) So I'm still trying to find the advantages of hg/git over svn. I'd love to get some hands-on experience, but there aren't any bigger projects we could move to hg/git yet, so I'm stuck with playing with small artifical projects that only contain a few made up files. And I'm looking for a few cases where you can feel the impressive power of hg/git, since so far I have often read about them but failed to find them myself.

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• Multithreading and Interrupts

  - by Nicholas Flynt

  I'm doing some work on the input buffers for my kernel, and I had some questions. On Dual Core machines, I know that more than one "process" can be running simultaneously. What I don't know is how the OS and the individual programs work to protect collisions in data. There are two things I'd like to know on this topic: (1) Where do interrupts occur? Are they guaranteed to occur on one core and not the other, and could this be used to make sure that real-time operations on one core were not interrupted by, say, file IO which could be handled on the other core? (I'd logically assume that the interrupts would happen on the 1st core, but is that always true, and how would you tell? Or perhaps does each core have its own settings for interrupts? Wouldn't that lead to a scenario where each core could react simultaneously to the same interrupt, possibly in different ways?) (2) How does the dual core processor handle opcode memory collision? If one core is reading an address in memory at exactly the same time that another core is writing to that same address in memory, what happens? Is an exception thrown, or is a value read? (I'd assume the write would work either way.) If a value is read, is it guaranteed to be either the old or new value at the time of the collision? I understand that programs should ideally be written to avoid these kinds of complications, but the OS certainly can't expect that, and will need to be able to handle such events without choking on itself.

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• Polymorphic Numerics on .Net and In C#

  - by Bent Rasmussen

  It's a real shame that in .Net there is no polymorphism for numbers, i.e. no INumeric interface that unifies the different kinds of numerical types such as bool, byte, uint, int, etc. In the extreme one would like a complete package of abstract algebra types. Joe Duffy has an article about the issue: http://www.bluebytesoftware.com/blog/CommentView,guid,14b37ade-3110-4596-9d6e-bacdcd75baa8.aspx How would you express this in C#, in order to retrofit it, without having influence over .Net or C#? I have one idea that involves first defining one or more abstract types (interfaces such as INumeric - or more abstract than that) and then defining structs that implement these and wrap types such as int while providing operations that return the new type (e.g. Integer32 : INumeric; where addition would be defined as public Integer32 Add(Integer32 other) { return Return(Value + other.Value); } I am somewhat afraid of the execution speed of this code but at least it is abstract. No operator overloading goodness... Any other ideas? .Net doesn't look like a viable long-term platform if it cannot have this kind of abstraction I think - and be efficient about it. Abstraction is reuse.

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