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• MySQL Connector/Net 6.5.5 Maintenance Release has been released

  - by fernando

  MySQL Connector/Net 6.5.5, a new maintenance release of our 6.5 series, has been released.  This release is GA quality and is appropriate for use in production environments.  Please note that 6.6 is our latest driver series and is the recommended product for development. It is now available in source and binary form from http://dev.mysql.com/downloads/connector/net/#downloads and mirror sites (note that not all mirror sites may be up to date at this point-if you can't find this version on some mirror, please try again later or choose another download site.) The 6.5.5 version of MySQL Connector/Net brings the following fixes: - Fix for ArgumentNull exception when using Take().Count() in a LINQ to Entities query (bug MySql #64749, Oracle bug #13913047). - Fix for type varchar changed to bit when saving in Table Designer (Oracle bug #13916560). - Fix for error when trying to change the name of an Index on the Indexes/Keys editor; along with this fix now users can change the Index type of a new Index which could not be done   in previous versions, and when changing the Index name the change is reflected on the list view at the left side of the Index/Keys editor (Oracle bug #13613801). - Fix for stored procedure call using only its name with EF code first (MySql bug #64999, Oracle bug #14008699). - Fix for List.Contains generates a bunch of ORs instead of more efficient IN clause in   LINQ to Entities (Oracle bug #14016344, MySql bug #64934). - Fix for performance issue in generated EF query: .NET StartsWith/Contains/EndsWith produces MySql's locate instead of Like (MySql bug #64935, Oracle bug #14009363). - Fix for script generated for code first contains wrong alter table and wrong declaration for byte[] (MySql bug #64216, Oracle bug #13900091). - Fix and code contribution for bug Timed out sessions are removed without notification which allow to enable the Expired CallBack when Session Provider times out any session (bug MySql #62266 Oracle bug # 13354935) - Fix for Exception thrown when using cascade delete in an EDM Model-First in Entity Framework (Oracle bug #14008752, MySql bug #64779). - Fix for Session locking issue with MySqlSessionStateStore (MySql bug #63997, Oracble bug #13733054). - Fixed deleting a user profile using Profile provider (MySQL bug #64470, Oracle bug #13790123) - Fix for bug Cannot Create an Entity with a Key of Type String (MySQL bug #65289, Oracle bug #14540202). This fix checks if the type has a FixedLength facet set in order to create a char otherwise should create varchar, mediumtext or longtext types when using a String CLR type in Code First or Model First also tested in Database First. Unit tests added for Code First and ProviderManifest. - Fix for bug "CacheServerProperties can cause 'Packet too large' error". The issue was due to a missing reading of Max_allowed_packet server property when CacheServerProperties is in true, since the value was read only in the first connection but the following pooled connections had a wrong value causing a Packet too large error. Including also a unit test for this scenario. All unit test passed. MySQL Bug #66578 Orabug #14593547. - Fix for handling unnamed parameter in MySQLCommand. This fix allows the mysqlcommand to handle parameters without requiring naming (e.g. INSERT INTO Test (id,name) VALUES (?, ?) ) (MySQL Bug #66060, Oracle bug #14499549). - Fixed inheritance on Entity Framework Code First scenarios. Discriminator column is created using its correct type as varchar(128) (MySql bug #63920 and Oracle bug #13582335). - Fixed "Trying to customize column precision in Code First does not work" (MySql bug #65001, Oracle bug #14469048). - Fixed bug ASP.NET Membership database fails on MySql database UTF32 (MySQL bug #65144, Oracle bug #14495292). - Fix for MySqlCommand.LastInsertedId holding only 32 bit values (MySql bug #65452, Oracle bug #14171960) by changing   several internal declaration of lastinsertid from int to long. - Fixed "Decimal type should have digits at right of decimal point", now default is 2, but user's changes in   EDM designer are recognized (MySql bug #65127, Oracle bug #14474342). - Fix for NullReferenceException when saving an uninitialized row in Entity Framework (MySql bug #66066, Oracle bug #14479715). - Fix for error when calling RoleProvider.RemoveUserFromRole(): causes an exception due to a wrong table being used (MySql bug #65805, Oracle bug #14405338). - Fix for "Memory Leak on MySql.Data.MySqlClient.MySqlCommand", too many MemoryStream's instances created (MySql bug #65696, Oracle bug #14468204). - Added ANTLR attribution notice (Oracle bug #14379162). - Fixed Entity Framework + mysql connector/net in partial trust throws exceptions (MySql bug #65036, Oracle bug #14668820). - Added support in Parser for Datetime and Time types with precision when using Server 5.6 (No bug Number). - Small improvement on MySqlPoolManager CleanIdleConnections for better mysqlpoolmanager idlecleanuptimer at startup (MySql bug #66472 and Oracle bug #14652624). - Fix for bug TIMESTAMP values are mistakenly represented as DateTime with Kind = Local (Mysql bug #66964, Oracle bug #14740705). - Fix for bug Keyword not supported. Parameter name: AttachDbFilename (Mysql bug #66880, Oracle bug #14733472). - Added support to MySql script file to retrieve data when using "SHOW" statements. - Fix for Package Load Failure in Visual Studio 2005 (MySql bug #63073, Oracle bug #13491674). - Fix for bug "Unable to connect using IPv6 connections" (MySQL bug #67253, Oracle bug #14835718). - Added auto-generated values for Guid identity columns (MySql bug #67450, Oracle bug #15834176). - Fix for method FirstOrDefault not supported in some LINQ to Entities queries (MySql bug #67377, Oracle bug #15856964). The release is available to download at http://dev.mysql.com/downloads/connector/net/6.5.html Documentation ------------------------------------- You can view current Connector/Net documentation at http://dev.mysql.com/doc/refman/5.5/en/connector-net.html You can find our team blog at http://blogs.oracle.com/MySQLOnWindows. You can also post questions on our forums at http://forums.mysql.com/. Enjoy and thanks for the support! 

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 5

  - by MarkPearl

  Learning Outcomes Describe the operation of a memory cell Explain the difference between DRAM and SRAM Discuss the different types of ROM Explain the concepts of a hard failure and a soft error respectively Describe SDRAM organization Semiconductor Main Memory The two traditional forms of RAM used in computers are DRAM and SRAM DRAM (Dynamic RAM) Divided into two technologies… Dynamic Static Dynamic RAM is made with cells that store data as charge on capacitors. The presence or absence of charge in a capacitor is interpreted as a binary 1 or 0. Because capacitors have natural tendency to discharge, dynamic RAM requires periodic charge refreshing to maintain data storage. The term dynamic refers to the tendency of the stored charge to leak away, even with power continuously applied. Although the DRAM cell is used to store a single bit (0 or 1), it is essentially an analogue device. The capacitor can store any charge value within a range, a threshold value determines whether the charge is interpreted as a 1 or 0. SRAM (Static RAM) SRAM is a digital device that uses the same logic elements used in the processor. In SRAM, binary values are stored using traditional flip flop logic configurations. SRAM will hold its data as along as power is supplied to it. Unlike DRAM, no refresh is required to retain data. SRAM vs. DRAM DRAM is simpler and smaller than SRAM. Thus it is more dense and less expensive than SRAM. The cost of the refreshing circuitry for DRAM needs to be considered, but if the machine requires a large amount of memory, DRAM turns out to be cheaper than SRAM. SRAMS are somewhat faster than DRAM, thus SRAM is generally used for cache memory and DRAM is used for main memory. Types of ROM Read Only Memory (ROM) contains a permanent pattern of data that cannot be changed. ROM is non volatile meaning no power source is required to maintain the bit values in memory. While it is possible to read a ROM, it is not possible to write new data into it. An important application of ROM is microprogramming, other applications include library subroutines for frequently wanted functions, System programs, Function tables. A ROM is created like any other integrated circuit chip, with the data actually wired into the chip as part of the fabrication process. To reduce costs of fabrication, we have PROMS. PROMS are… Written only once Non-volatile Written after fabrication Another variation of ROM is the read-mostly memory, which is useful for applications in which read operations are far more frequent than write operations, but for which non volatile storage is required. There are three common forms of read-mostly memory, namely… EPROM EEPROM Flash memory Error Correction Semiconductor memory is subject to errors, which can be classed into two categories… Hard failure – Permanent physical defect so that the memory cell or cells cannot reliably store data Soft failure – Random error that alters the contents of one or more memory cells without damaging the memory (common cause includes power supply issues, etc.) Most modern main memory systems include logic for both detecting and correcting errors. Error detection works as follows… When data is to be read into memory, a calculation is performed on the data to produce a code Both the code and the data are stored When the previously stored word is read out, the code is used to detect and possibly correct errors The error checking provides one of 3 possible results… No errors are detected – the fetched data bits are sent out An error is detected, and it is possible to correct the error. The data bits plus error correction bits are fed into a corrector, which produces a corrected set of bits to be sent out An error is detected, but it is not possible to correct it. This condition is reported Hamming Code See wiki for detailed explanation. We will probably need to know how to do a hemming code – refer to the textbook (pg. 188 – 189) Advanced DRAM organization One of the most critical system bottlenecks when using high-performance processors is the interface to main memory. This interface is the most important pathway in the entire computer system. The basic building block of main memory remains the DRAM chip. In recent years a number of enhancements to the basic DRAM architecture have been explored, and some of these are now on the market including… SDRAM (Synchronous DRAM) DDR-DRAM RDRAM SDRAM (Synchronous DRAM) SDRAM exchanges data with the processor synchronized to an external clock signal and running at the full speed of the processor/memory bus without imposing wait states. SDRAM employs a burst mode to eliminate the address setup time and row and column line precharge time after the first access In burst mode a series of data bits can be clocked out rapidly after the first bit has been accessed SDRAM has a multiple bank internal architecture that improves opportunities for on chip parallelism SDRAM performs best when it is transferring large blocks of data serially There is now an enhanced version of SDRAM known as double data rate SDRAM or DDR-SDRAM that overcomes the once-per-cycle limitation of SDRAM

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• MySQL Connector/Net 6.6.3 Beta 2 has been released

  - by fernando

  MySQL Connector/Net 6.6.3, a new version of the all-managed .NET driver for MySQL has been released.  This is the second of two beta releases intended to introduce users to the new features in the release. This release is feature complete it should be stable enough for users to understand the new features and how we expect them to work.  As is the case with all non-GA releases, it should not be used in any production environment.  It is appropriate for use with MySQL server versions 5.0-5.6. It is now available in source and binary form from http://dev.mysql.com/downloads/connector/net/#downloads and mirror sites (note that not all mirror sites may be up to date at this point-if you can't find this version on some mirror, please try again later or choose another download site.) The 6.6 version of MySQL Connector/Net brings the following new features:   * Stored routine debugging   * Entity Framework 4.3 Code First support   * Pluggable authentication (now third parties can plug new authentications mechanisms into the driver).   * Full Visual Studio 2012 support: everything from Server Explorer to Intellisense&   the Stored Routine debugger. Stored Procedure Debugging ------------------------------------------- We are very excited to introduce stored procedure debugging into our Visual Studio integration.  It works in a very intuitive manner by simply clicking 'Debug Routine' from Server Explorer. You can debug stored routines, functions&   triggers. These release contains fixes specific of the debugger as well as other fixes specific of other areas of Connector/NET:   * Added feature to define initial values for InOut stored procedure arguments.   * Debugger: Fixed Visual Studio locked connection after debugging a routine.   * Fix for bug Cannot Create an Entity with a Key of Type String (MySQL bug #65289, Oracle bug #14540202).   * Fix for bug "CacheServerProperties can cause 'Packet too large' error". MySQL Bug #66578 Orabug #14593547.   * Fix for handling unnamed parameter in MySQLCommand. This fix allows the mysqlcommand to handle parameters without requiring naming (e.g. INSERT INTO Test (id,name) VALUES (?, ?) ) (MySQL Bug #66060, Oracle bug #14499549).   * Fixed end of line issue when debugging a routine.   * Added validation to avoid overwriting a routine backup file when it hasn't changed.   * Fixed inheritance on Entity Framework Code First scenarios. (MySql bug #63920 and Oracle bug #13582335).   * Fixed "Trying to customize column precision in Code First does not work" (MySql bug #65001, Oracle bug #14469048).   * Fixed bug ASP.NET Membership database fails on MySql database UTF32 (MySQL bug #65144, Oracle bug #14495292).   * Fix for MySqlCommand.LastInsertedId holding only 32 bit values (MySql bug #65452, Oracle bug #14171960).   * Fixed "Decimal type should have digits at right of decimal point", now default is 2, and user's changes in     EDM designer are recognized (MySql bug #65127, Oracle bug #14474342).   * Fix for NullReferenceException when saving an uninitialized row in Entity Framework (MySql bug #66066, Oracle bug #14479715).   * Fix for error when calling RoleProvider.RemoveUserFromRole(): causes an exception due to a wrong table being used (MySql bug #65805, Oracle bug #14405338).   * Fix for "Memory Leak on MySql.Data.MySqlClient.MySqlCommand", too many MemoryStream's instances created (MySql bug #65696, Oracle bug #14468204).   * Added ANTLR attribution notice (Oracle bug #14379162).   * Fix for debugger failing when having a routine with an if-elseif-else.   * Also the programming interface for authentication plugins has been redefined. Some limitations remains, due to the current debugger architecture:   * Some MySQL functions cannot be debugged currently (get_lock, release_lock, begin, commit, rollback, set transaction level)..   * Only one debug session may be active on a given server. The Debugger is feature complete at this point. We look forward to your feedback. Documentation ------------------------------------- You can view current Connector/Net documentation at http://dev.mysql.com/doc/refman/5.5/en/connector-net.html You can find our team blog at http://blogs.oracle.com/MySQLOnWindows. You can also post questions on our forums at http://forums.mysql.com/. Enjoy and thanks for the support!

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• Many Different Things Rolled into a Ball

  - by MOSSLover

  Yeah I know I don’t blog much anymore, because life has taken me places that don’t involve the interwebs unfortunately.  I am in the midst of planning two events, starting a non for profit, creating more sessions for various conferences, submitting to various conferences, working a 40 hour a week job, attempting to hang out with boyfriend/friends/family.  So you can see that list does not include this blog sadly that’s how it goes sometimes.  The bottom piece very important over any of the top pieces.  I haven’t seen St. Louis in a while and I get to go back.  I was gone from home for MVP Summit and Best Practices Conference, so the boyfriend and cat didn’t get to see me either for a bit.  Then you have to add in the whole toilet being broken fiasco this week.  Maintenance really thought it would be cool to turn off the ability to flush.  I mean who does that?  Then when we call the owner he comes by turns it on and we figure it was an accident, because well the next day no one came by to tell us there was a leak.  It was all kinds of strangeness and involved me running to other people’s toilets.  As Dan Usher would say, I was a sad panda for a few days.  So I guess I wanted to post a few thoughts here just because I can.  I do not like multiple content editor webparts embedded with html files in numerous pages doing the same thing.  I will tell you why I don’t like these particular webparts and the way they are being used.  First off if you have a bunch of pages with script includes it’s about time you should just dump them into the masterpage.  Why bother finding all 20 pages and changing those pages when you can just use a single masterpage that already exists? The other thing that is bothering me days is screen scraping.  Just don’t do it, because in 2010 you will find the UI is substantially slower.  I understand you are new and you have no idea what to do.  You are also using 2007 am I right?  So then you need to go to codeplex.com and type in a search for SPServices.  Download it, use it, love it and then have it’s babies (well maybe don’t go so far this is not the GRID in Tron). If you have a ton of constants in your code why did you not go in and create a webpart with a bunch of properties and/or link to a configuration list hidden in the browser?  This type of property and list could help you out in the long run.  The power users and administrators can now change the control without you having to compile it over and over again.  It’s good stuff.  Also, you can change the control without compiling it, especially in 2007 where you have to do a farm solution.  In 2010 you can do a sandbox solution I guess, but shouldn’t you make it as easy and supportable as possible for other users? In conclusion I’m an angry person when it comes to viewing something repeatedly and analyzing it in a system.  Now we will move on to the next topic…MVP Summit…So yeah I can’t really talk about particulars, but I can talk about my experience as a person.  Don’t build something up to be cooler than it is only to be dropped from your 10,000 foot perch.  My experience was great, but the content overall was something to be desired.  It’s ok I got to meet a lot of people I would not have met if I had not gone.  Some of it was surreal, such as product group members showing up and talking to us.  It was pretty neat.  Plus I never had the chance to get to that mythical MS Office in Redmond.  Prior to Summit it was like Rainbow Brites unicorn trying taunting me on television when I was a kid.  So I guess with all that said I give it a B.  It was awesome in some way, but lacking in other ways.  The cool part is that I got to go.  Would I have lived without going? Yes, but it was still cool. I could prattle on about other things and make this post massive, but I’m going to pass and give myself a piece of Sunday to play Rockband and do 800 other things.  I hope the two of you who read this blog are well.  I’ll catch you all at another juncture.  Have a good weekend and varying holidays in between. Technorati Tags: SharePoint,MVP Summit,JQuery,Javascript

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• Are IE9 really good ?

  - by anirudha

  IE9 started a campaign for kill IE6 from the core because they know that IE6 is a big trouble or  problem for them for promote 9 version of IE. so they started a campaign for killing IE6. next time they kill IE 7 , 8,9 whenever they found this old version have a big problem for them to promote next version of IE.   Why they not make a update system who automatically update the browser and tell user to restart and update goes installed in the user system. well IE9 should learn from all other that they have very well design auto-update system who never give user in trouble that your browser goes old. Chrome and Firefox both update themselves and say user restart to enjoy another good version. in IE6 a big problem is that updates. no one sure that they installed new version of IE6 without any hassles and update goes install without any problem because they really know or care about “you need this to install this and this for this” so they thing “why I update IE whenever I am unsure that my browser goes update and I have no problem again” so they do nothing because their work done with no problem because common person used high profile application who work even in IE6. so they do nothing.    IE6 countdown website have designed a banner for warn or force user to upgrade to next version of IE. well there is no good reason for put the banner on website some of reason are:-   Windows 7 comes with pre-installed IE8 and Vista comes with upgrade version them IE6 so that is sure that you force a user who have Windows XP [luna] and if they want to upgrade IE then they can get IE8 not version 9 because IE9 is design for Windows 7 or Vista Service pack 2. so What is the use of update when user still have a outdate version too because IE8 is old version and not have any capability of HTML5 so forcing user by using the banner have no sense. I am not know why they all listed on website put the banner on their own website. it’s good that you offer user what they want instead of giving them a outdate version of IE again. My means to give a user list of browser they can try to enhance their browser experience instead of only IE.   IE9 build upon WPF and they spent more time on using WPF in IE instead of making user experience browser.  many thing is designed wrongly in IE first thing is tabs. the tabs in chrome are bigger and easily to move and same in Firefox even not have smooth tabbing. IE have same tabbing as chrome have but leak a point that it’s too small. if you really  want to move then sometime they create a problem that they going elsewhere from the current instance of IE.   Chrome have a big buttons, tabs and menu to enhance browser experience and Firefox have a good feature that you can make them bigger or small. you can put the icon for add-ons on the toolbar for easily use but IE have no relation with customization so we never can thinking about that.   When chrome provide lot’s of extensions and a  webstore for browser application and same feature in Firefox can be seen then there is no plugin in IE. really you can see their IE addons Website where no plugin listed for web development. even in the category or tag. as a response from many blog there is new for developer that new version of IE9 developer tool. well IE9 have three new tabs a blogger tell on their blog. when I trying them I found many thing but I still unable to edit the Css from the HTML tab and no plugin I found I can get to enhance IE9 web development. something more other provide never IE9 give me like personas , customization , browser extension or any other they used to tell a small thing customization  .   IE9 still have some problem with JavaScript that when I use Firefox and chrome and logout in both then my cookie is deleted but in IE it’s not done. it’s show me that IE9 still have different from other not for good thing even some bad thing too. When I trying to read a article that is written in Hindi using Unicode font I found that they show many thing misspelled. there is three Sha in Hindi but they all goes wrong in IE. the misprint thing is not that the writing  for the articles goes wrong. it’s problem or browser to rendering a font. the Firefox and chrome not give me this problem even opera render the font in italic style by decrease the font-size but all those work perfect.   in Pwn2Own the apple’s safari  and IE9 both are hacked. this is a awesome news for whose who thing that  open-source is lose in  Security and close-source is highly-secured software. well this is not a good parameter for talking about software. it’s should depend how much application tested and used. because more testing and more use of application make them better.   I  appreciate IE to making their new version 9 and good luck for them. there is a another matter that I personally found nothing on them.

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• Encrypt images before uploading to Dropbox [migrated]

  - by Cherry

  I want to encrypt a file first before the file will be uploaded to the dropbox. So i have implement the encryption inside the uploading of the codes. However, there is an error after i integrate the codes together. Where did my mistake go wrong? Error at putFileOverwriteRequest and it says The method putFileOverwriteRequest(String, InputStream, long, ProgressListener) in the type DropboxAPI is not applicable for the arguments (String, FileOutputStream, long, new ProgressListener(){}) Another problem is that this FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); i do not know where to put the file so that after i read the file, it will call the path and then upload to the Dropbox. Anyone is kind to help me in this? As time is running out for me and i still cant solve the problem. Thank you in advance. The full code is as below. public class UploadPicture extends AsyncTask<Void, Long, Boolean> { private DropboxAPI<?> mApi; private String mPath; private File mFile; private long mFileLen; private UploadRequest mRequest; private Context mContext; private final ProgressDialog mDialog; private String mErrorMsg; public UploadPicture(Context context, DropboxAPI<?> api, String dropboxPath, File file) { // We set the context this way so we don't accidentally leak activities mContext = context.getApplicationContext(); mFileLen = file.length(); mApi = api; mPath = dropboxPath; mFile = file; mDialog = new ProgressDialog(context); mDialog.setMax(100); mDialog.setMessage("Uploading " + file.getName()); mDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mDialog.setProgress(0); mDialog.setButton("Cancel", new OnClickListener() { public void onClick(DialogInterface dialog, int which) { // This will cancel the putFile operation mRequest.abort(); } }); mDialog.show(); } @Override protected Boolean doInBackground(Void... params) { try { KeyGenerator keygen = KeyGenerator.getInstance("DES"); SecretKey key = keygen.generateKey(); //generate key //encrypt file here first byte[] plainData; byte[] encryptedData; Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key); //File f = new File(mFile); //read file FileInputStream in = new FileInputStream(mFile); //obtains input bytes from a file plainData = new byte[(int)mFile.length()]; in.read(plainData); //Read bytes of data into an array of bytes encryptedData = cipher.doFinal(plainData); //encrypt data FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); //upload to a path first then call the path so that it can be uploaded up to the dropbox //save encrypted file to dropbox // By creating a request, we get a handle to the putFile operation, // so we can cancel it later if we want to //FileInputStream fis = new FileInputStream(mFile); String path = mPath + mFile.getName(); mRequest = mApi.putFileOverwriteRequest(path, fis, mFile.length(), new ProgressListener() { @Override public long progressInterval() { // Update the progress bar every half-second or so return 500; } @Override public void onProgress(long bytes, long total) { publishProgress(bytes); } }); if (mRequest != null) { mRequest.upload(); return true; } } catch (DropboxUnlinkedException e) { // This session wasn't authenticated properly or user unlinked mErrorMsg = "This app wasn't authenticated properly."; } catch (DropboxFileSizeException e) { // File size too big to upload via the API mErrorMsg = "This file is too big to upload"; } catch (DropboxPartialFileException e) { // We canceled the operation mErrorMsg = "Upload canceled"; } catch (DropboxServerException e) { // Server-side exception. These are examples of what could happen, // but we don't do anything special with them here. if (e.error == DropboxServerException._401_UNAUTHORIZED) { // Unauthorized, so we should unlink them. You may want to // automatically log the user out in this case. } else if (e.error == DropboxServerException._403_FORBIDDEN) { // Not allowed to access this } else if (e.error == DropboxServerException._404_NOT_FOUND) { // path not found (or if it was the thumbnail, can't be // thumbnailed) } else if (e.error == DropboxServerException._507_INSUFFICIENT_STORAGE) { // user is over quota } else { // Something else } // This gets the Dropbox error, translated into the user's language mErrorMsg = e.body.userError; if (mErrorMsg == null) { mErrorMsg = e.body.error; } } catch (DropboxIOException e) { // Happens all the time, probably want to retry automatically. mErrorMsg = "Network error. Try again."; } catch (DropboxParseException e) { // Probably due to Dropbox server restarting, should retry mErrorMsg = "Dropbox error. Try again."; } catch (DropboxException e) { // Unknown error mErrorMsg = "Unknown error. Try again."; } catch (FileNotFoundException e) { } return false; } @Override protected void onProgressUpdate(Long... progress) { int percent = (int)(100.0*(double)progress[0]/mFileLen + 0.5); mDialog.setProgress(percent); } @Override protected void onPostExecute(Boolean result) { mDialog.dismiss(); if (result) { showToast("Image successfully uploaded"); } else { showToast(mErrorMsg); } } private void showToast(String msg) { Toast error = Toast.makeText(mContext, msg, Toast.LENGTH_LONG); error.show(); } }

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• Qt vs .NET - plz no n00bs who don't know wtf they're talking about [closed]

  - by Pirate for Profit

  Man in all these Qt vs. .NET discussions 90% these people don't know WTF they're talking about. Trying to get a real comparison chart going before we embark on a major fucking project. And yes I'm drunk, and yes I use cocaine. Event Handling In Qt the event handling system you just emit signals when something cool happens and then catch them in slots, for instance emit valueChanged(int percent, bool something); and void MyCatcherObj::valueChanged(int p, bool ok){} blocking them and disconnecting them when needed, doing it across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET delegate crap is the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down i m o. Basically, the footprints make more sense and you can visualize the project easier without the clunky event handling system. I wish I could it explain it better. The only thing is, I do love some of the ease of C# compared to C++ and .NET's assembly architecture. That is a big bonus for modular projects, which are a PITA to do in C++. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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• Managing database connections in an Android Activity

  - by Daniel Lew

  I have an application with a ListActivity that uses a CursorAdapter as its adapter. The ListActivity opens the database and does the querying for the CursorAdapter, which is all well and good, but I am having issues with figuring out when to close both the Cursor and the SQLiteDatabase. The way things are handled right now, if the user finishes the activity, I close the database and the cursor. However, this still ends up with the DalvikVM warning me that I've left a database open - for example, if the user hits the "home" button (leaving the activity in the task's stack), rather than the "back" button. If I close them during pause and then re-query during resume, then I don't get any errors, but then a user cannot return to the list without it requerying (and thus losing the user's place in the list). By this I mean, the user can click on any item in the list and open a new activity based on it, but will often want to hit "back" afterwards and return to the same place on the list. If I requery, then I cannot return the user back to the correct spot. What is the proper way to handle this issue? I want the list to remain scrolled properly, but I don't want the VM to keep complaining about unclosed databases. Edit: Here's a general outline of how I handle the code at the moment: public class MyListActivity extends ListActivity { private Cursor mCursor; private CursorAdapter mAdapter; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mAdapter = new MyCursorAdapter(this); setListAdapter(mAdapter); } protected void onPause() { super.onPause(); if (isFinishing()) { mCursor.close(); } } protected void onDestroy() { super.onDestroy(); mCursor.close(); } private void updateQuery() { // If we had a cursor open before, close it. if (mCursor != null) { mCursor.close(); } MyDbHelper dbHelper = new MyDbHelper(this); SQLiteDatabase db = dbHelper.getReadableDatabase(); mCursor = db.query(...); mAdapter.changeCursor(mCursor); db.close(); } } updateQuery() can be called multiple times because the user can filter the results via menu items (I left this part out of the code, as the problem still occurs even if the user does no filtering). Again, the issue is that when I hit home I get leak errors. Yet, after going home, I can go back to the app and find my list again - cursor fully intact.

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• Windows Service HTTPListener Memory Issue

  - by crawshaws

  Hi all, Im a complete novice to the "best practices" etc of writing in any code. I tend to just write it an if it works, why fix it. Well, this way of working is landing me in some hot water. I am writing a simple windows service to server a single webpage. (This service will be incorperated in to another project which monitors the services and some folders on a group of servers.) My problem is that whenever a request is recieved, the memory usage jumps up by a few K per request and keeps qoing up on every request. Now ive found that by putting GC.Collect in the mix it stops at a certain number but im sure its not meant to be used this way. I was wondering if i am missing something or not doing something i should to free up memory. Here is the code: Public Class SimpleWebService : Inherits ServiceBase 'Set the values for the different event log types. Public Const EVENT_ERROR As Integer = 1 Public Const EVENT_WARNING As Integer = 2 Public Const EVENT_INFORMATION As Integer = 4 Public listenerThread As Thread Dim HTTPListner As HttpListener Dim blnKeepAlive As Boolean = True Shared Sub Main() Dim ServicesToRun As ServiceBase() ServicesToRun = New ServiceBase() {New SimpleWebService()} ServiceBase.Run(ServicesToRun) End Sub Protected Overrides Sub OnStart(ByVal args As String()) If Not HttpListener.IsSupported Then CreateEventLogEntry("Windows XP SP2, Server 2003, or higher is required to " & "use the HttpListener class.") Me.Stop() End If Try listenerThread = New Thread(AddressOf ListenForConnections) listenerThread.Start() Catch ex As Exception CreateEventLogEntry(ex.Message) End Try End Sub Protected Overrides Sub OnStop() blnKeepAlive = False End Sub Private Sub CreateEventLogEntry(ByRef strEventContent As String) Dim sSource As String Dim sLog As String sSource = "Service1" sLog = "Application" If Not EventLog.SourceExists(sSource) Then EventLog.CreateEventSource(sSource, sLog) End If Dim ELog As New EventLog(sLog, ".", sSource) ELog.WriteEntry(strEventContent) End Sub Public Sub ListenForConnections() HTTPListner = New HttpListener HTTPListner.Prefixes.Add("http://*:1986/") HTTPListner.Start() Do While blnKeepAlive Dim ctx As HttpListenerContext = HTTPListner.GetContext() Dim HandlerThread As Thread = New Thread(AddressOf ProcessRequest) HandlerThread.Start(ctx) HandlerThread = Nothing Loop HTTPListner.Stop() End Sub Private Sub ProcessRequest(ByVal ctx As HttpListenerContext) Dim sb As StringBuilder = New StringBuilder sb.Append("<html><body><h1>Test My Service</h1>") sb.Append("</body></html>") Dim buffer() As Byte = Encoding.UTF8.GetBytes(sb.ToString) ctx.Response.ContentLength64 = buffer.Length ctx.Response.OutputStream.Write(buffer, 0, buffer.Length) ctx.Response.OutputStream.Close() ctx.Response.Close() sb = Nothing buffer = Nothing ctx = Nothing 'This line seems to keep the mem leak down 'System.GC.Collect() End Sub End Class Please feel free to critisise and tear the code apart but please BE KIND. I have admitted I dont tend to follow the best practice when it comes to coding.

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• who free's setvbuf buffer?

  - by Evan Teran

  So I've been digging into how the stdio portion of libc is implemented and I've come across another question. Looking at man setvbuf I see the following: When the first I/O operation occurs on a file, malloc(3) is called, and a buffer is obtained. This makes sense, your program should have a malloc in it for I/O unless you actually use it. My gut reaction to this is that libc will clean up its own mess here. Which I can only assume it does because valgrind reports no memory leaks (they could of course do something dirty and not allocate it via malloc directly... but we'll assume that it literally uses malloc for now). But, you can specify your own buffer too... int main() { char *p = malloc(100); setvbuf(stdio, p, _IOFBF, 100); puts("hello world"); } Oh no, memory leak! valgrind confirms it. So it seems that whenever stdio allocates a buffer on its own, it will get deleted automatically (at the latest on program exit, but perhaps on stream close). But if you specify the buffer explicitly, then you must clean it up yourself. There is a catch though. The man page also says this: You must make sure that the space that buf points to still exists by the time stream is closed, which also happens at program termination. For example, the following is invalid: Now this is getting interesting for the standard streams. How would one properly clean up a manually allocated buffer for them, since they are closed in program termination? I could imagine a "clean this up when I close flag" inside the file struct, but it get hairy because if I read this right doing something like this: setvbuf(stdio, 0, _IOFBF, 100); printf("hello "); setvbuf(stdio, 0, _IOLBF, 100); printf("world\n"); would cause 2 allocations by the standard library because of this sentence: If the argument buf is NULL, only the mode is affected; a new buffer will be allocated on the next read or write operation.

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• How to integrate Purify into Hudson CI?

  - by Martin

  Hello everybody! I have a Hudson CI system set up and for the moment it is used for building a project and running some unit tests. My next step is to integrate the memory leak detector Purify into the build cycle. Now I want to start the unit tests also inside purify and for this I have created a new batch task which runs following command: purify.exe /SaveTextData MyExecutable.exe --test TestLibrary.dll --output xml As I read in the Purify documentation the /SaveTextData option is used in order to run purify not in GUI mode. If I run this command on my local workstation in the command line it works perfectly. But in case it is started by Hudson, nothing happens. Unfortunetly there are no logs of purify... Has someone ever tried to start purify either by Hudson or any other CI system? Thanks in advance. Best regards Martin EDIT: I forgot to tell you, that I have Hudson running as master and slave on different computers. On the master I have configured a task which should start the unit tests within purify on the slave. I am running the slave via JNLP. EDIT 18.03.2010: Ok, so finally I am a bit closer the source of the problem. I have discovered, that running my unit tests in purify locally the log file EngineCmdLine.log contains three commands. I am starting purify with following command: purify.exe /SaveTextData TestRunnerConsoleWD.exe --test TestDemoWD.dll Output of EngineCmdLine.log when starting purify manually: File: D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestRunnerConsoleWD.exe File: C:\WINDOWS\system32\ws2_32.dll File: D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestDemoWD.dll Output when starting via Hudson: File: D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestRunnerConsoleWD.exe File: C:\WINDOWS\system32\ws2_32.dll File: D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestDemoWD.dll File: D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestDemoWD.dll The error output of purify: Instrumenting: BtcTestDemoWD.dll 313856 bytes Purify: While processing file D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TESTFWWD.DLL: Error: Cannot replace file c:\Programme\IBM\RationalPurifyPlus\PurifyPlus\cache\BTCTESTFWWD$Purify_D_workspace_hudson_workspace_Purify_TestFW_CommonsCoreTest_Cpp_msvs9.DLL. Is it in use? TESTFWWD.DLL 505344 bytes Unable to instrument D:\workspace\hudson\workspace\Purify_TestFW_CommonsCoreTest_Cpp_msvs9\TestDemoWD.dll (0x1) Question is, why is purify starting twice a command with the TestDemoWD.dll library?

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• Am I Leaking ADO.NET Connections?

  - by HardCode

  Here is an example of my code in a DAL. All calls to the database's Stored Procedures are structured this way, and there is no in-line SQL. Friend Shared Function Save(ByVal s As MyClass) As Boolean Dim cn As SqlClient.SqlConnection = Dal.Connections.MyAppConnection Dim cmd As New SqlClient.SqlCommand Try cmd.Connection = cn cmd.CommandType = CommandType.StoredProcedure cmd.CommandText = "proc_save_my_class" cmd.Parameters.AddWithValue("@param1", s.Foo) cmd.Parameters.AddWithValue("@param2", s.Bar) Return True Finally Dal.Utility.CleanupAdoObjects(cmd, cn) End Try End Function Here is the Connection factory (if I am using the correct term): Friend Shared Function MyAppConnection() As SqlClient.SqlConnection Dim cn As New SqlClient.SqlConnection(ConfigurationManager.ConnectionStrings("MyConnectionString").ToString) cn.Open() If cn.State <> ConnectionState.Open Then ' CriticalException is a custom object inheriting from Exception. Throw New CriticalException("Could not connect to the database.") Else Return cn End If End Function Here is the Dal.Utility.CleaupAdoObjects() function: Friend Shared Sub CleanupAdoObjects(ByVal cmd As SqlCommand, ByVal cn As SqlConnection) If cmd IsNot Nothing Then cmd.Dispose() If cn IsNot Nothing AndAlso cn.State <> ConnectionState.Closed Then cn.Close() End Sub I am getting a lot of "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding." error messages reported by the users. The application's DAL opens a connection, reads or saves data, and closes it. No connections are ever left open - intentionally! There is nothing obvious on the Windows 2000 Server hosting the SQL Server 2000 that would indicate a problem. Nothing in the Event Logs and nothing in the SQL Server logs. The timeouts happen randomly - I cannot reproduce. It happens early in the day with only 1 to 5 users in the system. It also happens with around 50 users in the system. The most connections to SQL Server via Performance Monitor, for all databases, has been about 74. The timeouts happen in code that both saves to, and reads from, the database in different parts of the application. The stack trace does not point to one or two offending DAL functions. It's happened in many different places. Does my ADO.NET code appear to be able to leak connections? I've goolged around a bit, and I've read that if the connection pool fills up, this can happen. However, I'm not explicitly setting any connection pooling. I've even tried to increase the Connection Timeout in the connection string, but timeouts happen long before the 300 second (5 minute) value: <add name="MyConnectionString" connectionString="Data Source=MyServer;Initial Catalog=MyDatabase;Integrated Security=SSPI;Connection Timeout=300;"/> I'm at a total loss already as to what is causing these Timeout issues. Any ideas are appreciated.

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• C Programming - My program is good enough for my assignment but I know its not good

  - by Joe

  Hi there I'm just starting an assignment for uni and it's raised a question for me. I don't understand how to return a string from a function without having a memory leak. char* trim(char* line) { int start = 0; int end = strlen(line) - 1; /* find the start position of the string */ while(isspace(line[start]) != 0) { start++; } //printf("start is %d\n", start); /* find the position end of the string */ while(isspace(line[end]) != 0) { end--; } //printf("end is %d\n", end); /* calculate string length and add 1 for the sentinel */ int len = end - start + 2; /* initialise char array to len and read in characters */ int i; char* trimmed = calloc(sizeof(char), len); for(i = 0; i < (len - 1); i++) { trimmed[i] = line[start + i]; } trimmed[len - 1] = '\0'; return trimmed; } as you can see I am returning a pointer to char which is an array. I found that if I tried to make the 'trimmed' array by something like: char trimmed[len]; then the compiler would throw up a message saying that a constant was expected on this line. I assume this meant that for some reason you can't use variables as the array length when initialising an array, although something tells me that can't be right. So instead I made my array by allocating some memory to a char pointer. I understand that this function is probably waaaaay sub-optimal for what it is trying to do, but what I really want to know is: 1. Can you normally initialise an array using a variable to declare the length like: char trimmed[len]; ? 2. If I had an array that was of that type (char trimmed[]) would it have the same return type as a pointer to char (ie char*). 3. If I make my array by callocing some memory and allocating it to a char pointer, how do I free this memory. It seems to me that once I have returned this array, I can't access it to free it as it is a local variable. Many thanks in advance Joe

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• C#: BackgroundWorker cloning resources?

  - by Dav

  The problem I've been struggling with this partiular problem for two days now and just run out of ideas. A little... background: we have a WinForms app that needs to access a database, construct a list of related in-memory objects from that data, and then display on a DataGridView. Important point is that we first populate an app-wide cache (List), and then create a mirror of the cache local to the form on which the DGV lives (using List constructor param). Because fetching the data takes a good few seconds (DB sits on a LAN server) to load, we decided to use a BackgroundWorker, and only refresh the DGV once the data is loaded. However, it seems that doing the loading via a BGW results in some memory leak... or an error on my part. When loaded using a blocking method call, the app consumes about 30MB of RAM; with a BGW this jumps to 80MB! While it may not seem as much anyway, our clients are not too happy about it. Relevant code Form private void MyForm_Load(object sender, EventArgs e) { MyRepository.Instance.FinishedEvent += RefreshCache; } private void RefreshCache(object sender, EventArgs e) { dgvProducts.DataSource = new List<MyDataObj>(MyRepository.Products); } Repository private static List<MyDataObj> Products { get; set; } public event EventHandler ProductsLoaded; public void GetProductsSync() { List<MyDataObj> p; using (MyL2SDb db = new MyL2SDb(MyConfig.ConnectionString)) { p = db.PRODUCTS .Select(p => new MyDataObj {Id = p.ID, Description = p.DESCR}) .ToList(); } Products = p; // tell the form to refresh UI if (ProductsLoaded != null) ProductsLoaded(this, null); } public void GetProductsAsync() { using (BackgroundWorker myWorker = new BackgroundWorker()) { myWorker.DoWork += delegate { List<MyDataObj> p; using (MyL2SDb db = new MyL2SDb(MyConfig.ConnectionString)) { p = db.PRODUCTS .Select(p => new MyDataObj {Id = p.ID, Description = p.DESCR}) .ToList(); } Products = p; }; // tell the form to refresh UI when finished myWorker.RunWorkerCompleted += GetProductsCompleted; myWorker.RunWorkerAsync(); } } private void GetProductsCompleted(object sender, RunWorkerCompletedEventArgs e) { if (ProductsLoaded != null) ProductsLoaded(this, null); } End! GetProductsSync or GetProductsAsync are called on the main thread, not shown above. Could it be that the GarbageCollector just gets lost with two threads? Or is it the task manager that shows incorrect values? Will be greateful for any responses, suggestions, criticism.

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• Problem with memory leaks

  - by user191723

  Sorry, having difficulty formattin code to appear correct here??? I am trying to understand the readings I get from running instruments on my app which are telling me I am leaking memory. There are a number, quite a few in fact, that get reported from inside the Foundation, AVFoundation CoreGraphics etc that I assume I have no control over and so should ignore such as: Malloc 32 bytes: 96 bytes, AVFoundation, prepareToRecordQueue or Malloc 128 bytes: 128 bytes, CoreGraphics, open_handle_to_dylib_path Am I correct in assuming these are something the system will resolve? But then there are leaks that are reported that I believe I am responsible for, such as: This call reports against this line leaks 2.31KB [self createAVAudioRecorder:frameAudioFile]; Immediately followed by this: -(NSError*) createAVAudioRecorder: (NSString *)fileName { // flush recorder to start afresh [audioRecorder release]; audioRecorder = nil; // delete existing file to ensure we have clean start [self deleteFile: fileName]; VariableStore *singleton = [VariableStore sharedInstance]; // get full path to target file to create NSString *destinationString = [singleton.docsPath stringByAppendingPathComponent: fileName]; NSURL *destinationURL = [NSURL fileURLWithPath: destinationString]; // configure the recording settings NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] initWithCapacity:6]; //****** LEAKING 384 BYTES [recordSettings setObject:[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey: AVFormatIDKey]; //***** LEAKING 32 BYTES float sampleRate = 44100.0; [recordSettings setObject:[NSNumber numberWithFloat: sampleRate] forKey: AVSampleRateKey]; //***** LEAKING 48 BYTES [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey]; int bitDepth = 16; [recordSettings setObject: [NSNumber numberWithInt:bitDepth] forKey:AVLinearPCMBitDepthKey]; //***** LEAKING 48 BYTES [recordSettings setObject:[NSNumber numberWithBool:YES] forKey:AVLinearPCMIsBigEndianKey]; [recordSettings setObject:[NSNumber numberWithBool: NO]forKey:AVLinearPCMIsFloatKey]; NSError *recorderSetupError = nil; // create the new recorder with target file audioRecorder = [[AVAudioRecorder alloc] initWithURL: destinationURL settings: recordSettings error: &recorderSetupError]; //***** LEAKING 1.31KB [recordSettings release]; recordSettings = nil; // check for erros if (recorderSetupError) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"Can't record" message: [recorderSetupError localizedDescription] delegate: nil cancelButtonTitle: @"OK" otherButtonTitles: nil]; [alert show]; [alert release]; alert = nil; return recorderSetupError; } [audioRecorder prepareToRecord]; //***** LEAKING 512 BYTES audioRecorder.delegate = self; return recorderSetupError; } I do not understand why there is a leak as I release audioRecorder at the start and set to nil and I release recordSettings and set to nil? Can anyone enlighten me please? Thanks

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• What is NSString in struct?

  - by 4thSpace

  I've defined a struct and want to assign one of its values to a NSMutableDictionary. When I try, I get a EXC_BAD_ACCESS. Here is the code: //in .h file typedef struct { NSString *valueOne; NSString *valueTwo; } myStruct; myStruct aStruct; //in .m file - (void)viewDidLoad { [super viewDidLoad]; aStruct.valueOne = @"firstValue"; } //at some later time [myDictionary setValue:aStruct.valueOne forKey:@"key1"]; //dies here with EXC_BAD_ACCESS This is the output in debugger console: (gdb) p aStruct.valueOne $1 = (NSString *) 0xf41850 Is there a way to tell what the value of aStruct.valueOne is? Since it is an NSString, why does the dictionary have such a problem with it? ------------- EDIT ------------- This edit is based on some comments below. The problem appears to be in the struct memory allocation. I have no issues assigning the struct value to the dictionary in viewDidLoad, as mentioned in one of the comments. The problem is that later on, I run into an issue with the struct. Just before the error, I do: po aStruct.oneValue Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x00000000 0x9895cedb in objc_msgSend () The program being debugged was signaled while in a function called from GDB. GDB has restored the context to what it was before the call. To change this behavior use "set unwindonsignal off" Evaluation of the expression containing the function (_NSPrintForDebugger) will be abandoned. This occurs just before the EXC_BAD_ACCESS: NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setDateFormat:@"MM-dd-yy_HH-mm-ss-A"]; NSString *date = [formatter stringFromDate:[NSDate date]]; [formatter release]; aStruct.valueOne = date; So the memory issue is most likely in my releasing of formatter. The date var has no retain. Should I instead be doing NSString *date = [[formatter stringFromDate:[NSDate date]] retain]; Which does work but then I'm left with a memory leak.

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• QT vs. Net - REAL comparisons for R.A.D. projects

  - by Pirate for Profit

  Man in all these Qt vs. .NET discussions 90% these people argue about the dumbest crap. Trying to get a real comparison chart here, because I know a little about both frameworks but I don't know everything. I believe Qt and .NET both have strengths and weaknesses. This is to make a comparison that highlights these so people can make more informed decisions before embarking on a project, in the spirit of R.A.D. Event Handling In Qt the event handling system is very simple. You just emit signals when something cool happens and then catch them in slots. ie. // run some calculations, then emit valueChanged(30, false, 20.2); and then catching it, any object can make a slot to recieve that message easily void MyObj::valueChanged(int percent, bool ok, float timeRemaining). It's easy to "block" an event or "disconnect" when needed, and works seamlessly across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, void valueChanged(object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET anonymous delegates are the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down for the simplest yet still flexible event handling system ever i m o. Plugins and such I do love some of the ease of C# compared to C++, as well as .NET's assembly architecture, even though it leads to a bunch of .dll's (there's ways to combine everything into a single exe though). That is a big bonus for modular projects, which are a PITA to import stuff in C++ as far as RAD is concerned. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. QConcurrent is the simplest threading mechanism I've ever played with. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? Doesn't the just-in-time compiler make native code that is pretty good, like and that only happens the first time the program is run? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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• Is there any reasonable use of a function returning an anonymous struct?

  - by Akanksh

  Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } return t; } struct { float a, b; }* foo(float a, float b) { if(a==0) return 0; return func(foo(a-1,b), a, b); } int main() { std::cout << foo(5,6)->a << std::endl; std::cout << foo(5,6)->b << std::endl; void* v = (void*)(foo(5,6)); float* f = (float*)(v); //[1] delete f now because I know struct is floats only. std::cout << f[0] << std::endl; std::cout << f[1] << std::endl; delete[] f; return 0; } There are a few points I would like to discuss: As is apparent, this code leaks, is there anyway I can NOT leak without knowing what the underlying struct definition is? see Comment [1]. I have to return a pointer to an anonymous struct so I can create an instance of the object within the templatized function func, can I do something similar without returning a pointer? I guess the most important, is there ANY (real-world) use for this at all? As the example given above leaks and is admittedly contrived. By the way, what the function foo(a,b) does is, to return a struct containing two numbers, the sum of all numbers from 1 to a and the product of a and b. EDIT: Maybe the line new T could use a boost::shared_ptr somehow to avoid leaks, but I haven't tried that. Would that work?

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• Qt vs .NET - a few comparisons [closed]

  - by Pirate for Profit

  Event Handling In Qt the event handling system you just emit signals when something cool happens and then catch them in slots, for instance emit valueChanged(int percent, bool something); and void MyCatcherObj::valueChanged(int p, bool ok){} blocking them and disconnecting them when needed, doing it across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET delegate crap is the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down i m o. Basically, the footprints make more sense and you can visualize the project easier without the clunky event handling system. I wish I could it explain it better. The only thing is, I do love some of the ease of C# compared to C++ and .NET's assembly architecture. That is a big bonus for modular projects, which are a PITA to do in C++. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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• operator+ overload returning object causing memory leaks, C++

  - by lampshade

  The problem i think is with returing an object when i overload the + operator. I tried returning a reference to the object, but doing so does not fix the memory leak. I can comment out the two statements: dObj = dObj + dObj2; and cObj = cObj + cObj2; to free the program of memory leaks. Somehow, the problem is with returning an object after overloading the + operator. #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); Dog operator+(const Dog &dObj); private : char * name; char * gender; int age; }; class MyClass { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); private : Animal * action; }; Dog::Dog(const char * name, const char * gender, int age) : // allocating here, for data passed in ctor name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } Dog Dog::operator+(const Dog &dObj) { Dog d; d.age = age + dObj.age; return d; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } int main() { MyClass mObj; Dog dObj("Scruffy", "Male", 4); // passing data into ctor Dog dObj2("Scooby", "Male", 6); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj = dObj + dObj2; // invoke the operator+ return 0; }

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• javascript simple object creation test: opera leaks?

  - by joe

  Hi, I am trying to figure out certain memory leak conditions in javascript on a few browsers. Currently I'm only testing FF 3.6, Opera 10.10, and Safari 4.0.3. I've started with a fairly simple test, and can confirm no memory leaks in Firefox and Safari. But Opera just takes memory and never gives it back. What gives? Here's the test: <html> <head> <script type="text/javascript"> window.onload = init; //window.onunload = cleanup; var a=[]; function init() { var d = document.createElement('div'); d.innerHTML = "page loading..."; document.body.appendChild(d); for (var i=0; i<400000; i++) { a[i] = new Obj("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); } d.innerHTML = "PAGE LOADED"; } function cleanup() { for (var i=0; i<400000; i++) { a[i] = null; } } function Obj(msg) { this.msg=msg; } </script> </head> <body> </body> </html> I shouldn't need the cleanup() call on window.unload, but tried that also. No luck. As you can see this is simple JS, no circular DOM links, no closures. I monitor the memory usage using 'top' on Mac 10.4.11. Memory usage spikes up on page load, as expected. In FF and Safari reloading the page does not use any further memory, and all memory is returned when the window (tab) is closed. In Opera, memory spikes on load, and seems to also spike further on each reload (but not always...). But regardless of reload, memory never goes back down below the initial load spike. I had hoped this was a no-brainer test that all browsers would pass, so I could move on to more "interesting" conditions. Am I doing something wrong here? Or is this a known Opera issue? Thanks! -joe

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• Idiomatic use of auto_ptr to transfer ownership to a container

  - by heycam

  I'm refreshing my C++ knowledge after not having used it in anger for a number of years. In writing some code to implement some data structure for practice, I wanted to make sure that my code was exception safe. So I've tried to use std::auto_ptrs in what I think is an appropriate way. Simplifying somewhat, this is what I have: class Tree { public: ~Tree() { /* delete all Node*s in the tree */ } void insert(const string& to_insert); ... private: struct Node { ... vector<Node*> m_children; }; Node* m_root; }; template<T> void push_back(vector<T*>& v, auto_ptr<T> x) { v.push_back(x.get()); x.release(); } void Tree::insert(const string& to_insert) { Node* n = ...; // find where to insert the new node ... push_back(n->m_children, auto_ptr<Node>(new Node(to_insert)); ... } So I'm wrapping the function that would put the pointer into the container, vector::push_back, and relying on the by-value auto_ptr argument to ensure that the Node* is deleted if the vector resize fails. Is this an idiomatic use of auto_ptr to save a bit of boilerplate in my Tree::insert? Any improvements you can suggest? Otherwise I'd have to have something like: Node* n = ...; // find where to insert the new node auto_ptr<Node> new_node(new Node(to_insert)); n->m_children.push_back(new_node.get()); new_node.release(); which kind of clutters up what would have been a single line of code if I wasn't worrying about exception safety and a memory leak. (Actually I was wondering if I could post my whole code sample (about 300 lines) and ask people to critique it for idiomatic C++ usage in general, but I'm not sure whether that kind of question is appropriate on stackoverflow.)

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• deleting element objects of a std vector using erase : a) memory handling and b) better way?

  - by memC

  hi, I have a vec_A that stores instances of class A as: vec_A.push_back(A()); I want to remove some elements in the vector at a later stage and have two questions: a) The element is deleted as: vec_A.erase(iterator) Is there any additional code I need to add to make sure that there is no memory leak? . b) Assume that condition if(num <5) is if num is among a specific numberList. Given this, is there a better way to delete the elements of a vector than what I am illustrating below? #include<vector> #include<stdio.h> #include<iostream> class A { public: int getNumber(); A(int val); ~A(){}; private: int num; }; A::A(int val){ num = val; }; int A::getNumber(){ return num; }; int main(){ int i =0; int num; std::vector<A> vec_A; std::vector<A>::iterator iter; for ( i = 0; i < 10; i++){ vec_A.push_back(A(i)); } iter = vec_A.begin(); while(iter != vec_A.end()){ std::cout << "\n --------------------------"; std::cout << "\n Size before erase =" << vec_A.size(); num = iter->getNumber() ; std::cout << "\n num = "<<num; if (num < 5){ vec_A.erase(iter); } else{ iter++; } std::cout << "\n size after erase =" << vec_A.size(); } std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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• vector related memory allocation question

  - by memC

  hi all, I am encountering the following bug. I have a class Foo . Instances of this class are stored in a std::vector vec of class B. in class Foo, I am creating an instance of class A by allocating memory using new and deleting that object in ~Foo(). the code compiles, but I get a crash at the runtime. If I disable delete my_a from desstructor of class Foo. The code runs fine (but there is going to be a memory leak). Could someone please explain what is going wrong here and suggest a fix? thank you! class A{ public: A(int val); ~A(){}; int val_a; }; A::A(int val){ val_a = val; }; class Foo { public: Foo(); ~Foo(); void createA(); A* my_a; }; Foo::Foo(){ createA(); }; void Foo::createA(){ my_a = new A(20); }; Foo::~Foo(){ delete my_a; }; class B { public: vector<Foo> vec; void createFoo(); B(){}; ~B(){}; }; void B::createFoo(){ vec.push_back(Foo()); }; int main(){ B b; int i =0; for (i = 0; i < 5; i ++){ std::cout<<"\n creating Foo"; b.createFoo(); std::cout<<"\n Foo created"; } std::cout<<"\nDone with Foo creation"; std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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• "Use of uninitialised value" despite of memset

  - by Framester

  Hi there, I allocate a 2d array and use memset to fill it with zeros. #include<stdio.h> #include<string.h> #include<stdlib.h> void main() { int m=10; int n =10; int **array_2d; array_2d = (int**) malloc(m*sizeof(int*)); if(array_2d==NULL) { printf("\n Could not malloc 2d array \n"); exit(1); } for(int i=0;i<m;i++) { ((array_2d)[i])=malloc(n*sizeof(int)); memset(((array_2d)[i]),0,sizeof(n*sizeof(int))); } for(int i=0; i<10;i++){ for(int j=0; j<10;j++){ printf("(%i,%i)=",i,j); fflush(stdout); printf("%i ", array_2d[i][j]); } printf("\n"); } } Afterwards I use valgrind [1] to check for memory errors. I get following error: Conditional jump or move depends on uninitialised value(s) for line 24 (printf("%i ", array_2d[i][j]);). I always thought memset is the function to initialize arrays. How can I get rid off this error? Thanks! Valgrind output: ==3485== Memcheck, a memory error detector ==3485== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==3485== Using Valgrind-3.5.0-Debian and LibVEX; rerun with -h for copyright info ==3485== Command: ./a.out ==3485== (0,0)=0 (0,1)===3485== Use of uninitialised value of size 4 ==3485== at 0x409E186: _itoa_word (_itoa.c:195) ==3485== by 0x40A1AD1: vfprintf (vfprintf.c:1613) ==3485== by 0x40A8FFF: printf (printf.c:35) ==3485== by 0x8048724: main (playing_with_valgrind.c:39) ==3485== ==3485== ==3485== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- ==3485== Conditional jump or move depends on uninitialised value(s) ==3485== at 0x409E18E: _itoa_word (_itoa.c:195) ==3485== by 0x40A1AD1: vfprintf (vfprintf.c:1613) ==3485== by 0x40A8FFF: printf (printf.c:35) ==3485== by 0x8048724: main (playing_with_valgrind.c:39) [1] valgrind --tool=memcheck --leak-check=yes --show-reachable=yes --num-callers=20 --track-fds=yes --db-attach=yes ./a.out [gcc-cmd] gcc -std=c99 -lm -Wall -g3 playing_with_valgrind.c

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