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  • Online file storage similar to Amazon S3

    - by Joel G
    I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe RESTful but extras like mkdir and cp (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

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  • Issue reading in a cell from Excel with Apache POI

    - by Nick
    I am trying to use Apache POI to read in old (pre-2007 and XLS) Excel files. My program goes to the end of the rows and iterates back up until it finds something that's not either null or empty. Then it iterates back up a few times and grabs those cells. This program works just fine reading in XLSX and XLS files made in Office 2010. I get the following error message: Exception in thread "main" java.lang.NumberFormatException: empty String at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source) at java.lang.Double.parseDouble(Unknown Source) at the line: num = Double.parseDouble(str); from the code: str = cell.toString(); if (str != "" || str != null) { System.out.println("Cell is a string"); num = Double.parseDouble(str); } else { System.out.println("Cell is numeric."); num = cell.getNumericCellValue(); } where the cell is the last cell in the document that's not empty or null. When I try to print the first cell that's not empty or null, it prints nothing, so I think I'm not accessing it correctly.

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  • How to best launch C++ application from web page

    - by JB
    I guess there are two parts to this question, one technical and one best practice for security and doing things "right". I'm working on a little game using C++ / directx but I would like to be able to launch it from a web page by someone clicking on a link on that page. Ideally I would like the first time they clicked for it to launch an installer downloads and installs the game on their machine, and then the next time to launch an application which updates the game from a web site if it's old and then launches it. I have no problems with the expected security popups and questions the first time it runs. I want people to be certain what they are installing and understand what they are doing. But it would be nice if once it is installed they could run it with the minimum of fuss. My question then is what technologies I could use to do this? I'm thinking that it would need a browser plugin and an activex control so that first time you'd install that, and subsequently the control/plugin would be able to launch the game. I'm not sure that under newer browser secuity models that a plugin would have the permissions to be able to run an installer though or silently invoke applications on the client machine even if they are already installed. Is there a more sensible way to achive what I want to achieve? And I'm worried about the security aspects too. I want this to be convenient for users but I of course want to do it "right". I know this can be done as I've seen several mmorpg type games that launch in this way from the browser now but it's not entirely clear to me how they've done it.

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  • Why is Firefox prompting to download a file that is POST'd to?

    - by alex
    This is the most peculiar thing. It is from an old in house CMS. When I attempt to submit my changes, it prompts to save the file linked in the action attribute of the form. Headers Request POST /~site/edit/articles/article_save.php?id=54 HTTP/1.1 Host: example.com User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Referer: http://example.com Content-Type: multipart/form-data; boundary=---------------------------10102754414578508781458777923 Content-Length: 940 -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="title" Home Content -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="catid" 18 -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="activecheck" 1 -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="image" -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="contentWidgToolbarSelectBlock" <p> -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="content" <p>Edit your article in this text box.</p> -----------------------------10102754414578508781458777923 Content-Disposition: form-data; name="contentWidgEditor" true -----------------------------10102754414578508781458777923-- Response HTTP/0.9 200 OK And then Firefox shows.... I can't determine from the response headers as to why this is prompting to open/save. It has always worked. All other PHP files on the site work fine. Anyone have a clue? Thanks Update Apparently, it just crashes Safari.

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  • Does unboxing just return a pointer to the value within the boxed object on the heap?

    - by Charles
    I this MSDN Magazine article, the author states (emphasis mine): Note that boxing always creates a new object and copies the unboxed value's bits to the object. On the other hand, unboxing simply returns a pointer to the data within a boxed object: no memory copy occurs. However, it is commonly the case that your code will cause the data pointed to by the unboxed reference to be copied anyway. I'm confused by the sentence I've bolded and the sentence that follows it. From everything else I've read, including this MSDN page, I've never before heard that unboxing just returns a pointer to the value on the heap. I was under the impression that unboxing would result in you having a variable containing a copy of the value on the stack, just as you began with. After all, if my variable contains "a pointer to the value on the heap", then I haven't got a value type, I've got a pointer. Can someone explain what this means? Was the author on crack? (There is at least one other glaring error in the article). And if this is true, what are the cases where "your code will cause the data pointed to by the unboxed reference to be copied anyway"? I just noticed that the article is nearly 10 years old, so maybe this is something that changed very early on in the life of .Net.

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  • Resque: Slow worker startup and Forking

    - by David John
    I'm currently moving my application from a Linode setup to EC2. Redis is currently installed on a remote instance with various worker instances interacting with the queue. Thats all going fantastic. My problem is with the amount of time it takes for a worker to be 'instantiated' and slow forking. Starting a worker will usually take between 30 seconds and a minute(from god.rb starting the worker rake task and the worker actively starting work on the queue). I could live with that, but I've not experienced such a wait time on my current Linode production box so I believe its one of my symptoms to a bigger problem. Next issue is that jobs that took a second or less in my previous environment now seem to take about 5 to 10 times longer.. I'm assuming this must be some sort of issue with my Ubuntu install on EC2? One notable difference is that I'm running REE 1.8.7-2010.01 in my new setup, and REE 1.8.6 on the old Linode boxes. Anyone else experienced these issues?

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  • .htaccess redirect or rewrite to default language url

    - by Saif Bechan
    I have a website that is currently in Dutch. Now I want to make the website multi-language starting with English. I am not that good at .htaccess files and the information on the web is quite confusing. The website I have now uses pretty urls, so all my urls look like this: http://mydomain.com/about/info http://mydomain.com/about/contact The code that I use for that is the following: <IfModule mod_rewrite.c> RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-l RewriteRule ^(.*)$ index.php?rt=$1 [L,QSA] </IfModule> I really do not know what this means, esp the [L,QSA]. But it's ok, it works for now. But now I want to add a default redirect to the code. So it becomes as follow http://mydomain.com becomes http://mydomain.com/nl I assume all my old links http://mydomain.com/about/info will not work anymore, but that is a step I am willing to take. Can someone please help me with this code. I have seen a lot of peaces of code, but I can not find the right one.

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  • Desktop-like UI implementations for Java web applications?

    - by localshred
    At work we're discussing upgrading our view layer for our web application. We're currently running an old and "modified" version of FreeMarker Classic, which is a pain to work with. One of our developers suggested using a Component UI style architecture similar to desktop style environments. Essentially, this would mean that you would build custom HTML components as Java Classes that the controller would render into the Document view. This would completely take away the need to write HTML into a view layer. The Components would generate the view layer for you. For instance, the following rendered HTML: <h1>I am a title</h1> <p>I am a paragraph.</p> Would be generated by doing something like: String titleString = "I am a title"; html.elements.Heading heading = new html.elements.Heading(Heading.H1, titleString); String paraString = "I am a paragraph."; html.elements.Paragraph paragraph = new html.elements.Paragraph(paraString); PrintWriter somePrintWriter = new PrintWriter(); Document document = new Document(); document.addElement(heading); document.addElement(paragraph); document.compose(somePrintWriter); The above code is just an example, don't critique the names or style, I just wrote it for a quick demonstration of what we may be trying to accomplish. I'm trying to determine if this has been done before in Java, and if so if there are any links I can be pointed to. I've been researching it as much as I can, but haven't found any implementations that completely remove the template layer (such as JSP or JSF). Thanks!

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  • Android shared library which is not JNI based

    - by Mondain
    I am developing a library for Android applications which does not use native code (JNI). I have tried suppling the library as an external jar in my Android projects but this method does not include the library contents in the apk and thus throws class not found errors when run in the emulator or device. I have also tried creating the library as an Android project in itself and this does work, but only for public static properties (not methods). With the library and application both being in separate apk's I can see that the VM notices references to the library and can read some properties, but when an attempt to instantiate a class in the library is executed I get class not found even though I can read the public static properties from it (very frustrating!!). I realize that Davlik byte code is not the same as Java byte code but I am having trouble even finding good information about how to solve what would seem to be a very simple issue in Android. I am looking into the old PlatformLibrary stuff right now but I am not convinced this will work either since the sample has been removed from the Android site :( So help me out if you can, if I find the answer before this happens I will share it. viva la Android!

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  • Why does this attempt at preloading images with jQuery not work?

    - by Eric
    Current I have this code: var imgCount = 36; var container = $('#3D-spin'); var loaded = 0; function onLoad() { alert(loaded); loaded++; if(loaded >= imgCount) { alert('yay'); } } for(var i = imgCount-1; i >= 0; i--) { container.prepend( $('<img>') .one('load', onLoad) .attr('alt', 'View from '+(i*360/imgCount)+'\u00B0') .attr('src', '/images/3d-spin/robot ('+i+').jpg') ); } However, it's behaving VERY strangely. Normally, I get no alert boxes. However, if I open developer tools, and pause script execution, I get a single alert that says 0. There's nothign like a good old heisenbug! A live example can be found here. The script itself is called style.js, and it is clear that images have loaded. Am I doing something stupidly, or is jQuery playing up?

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  • HTTP Compression problems on IIS7

    - by Jonathan Wood
    I've spent quite a bit of time on this but seem to be going nowhere. I have a large page that I really want to speed up. The obvious place to start seems to be HTTP compression, but I just can't seem to get it to work for me. After considerable searching, I've tried several variations of the code below. It kind of works, but after refreshing the browser, the results seem to fall apart. They were turning to garbage when the page used caching. If I turn off caching, then the page seems right but I lose my CSS formatting (stored in a separate file) and get an error that an included JS file contains invalid characters. Most of the resources I've found on the Web were either very old or focused on accessing IIS directly. My page is running on a shared hosting account and I do not have direct access to IIS7, which it's running on. protected void Application_BeginRequest(object sender, EventArgs e) { // Implement HTTP compression if (Request["HTTP_X_MICROSOFTAJAX"] == null) // Avoid compressing AJAX calls { // Retrieve accepted encodings string encodings = Request.Headers.Get("Accept-Encoding"); if (encodings != null) { // Verify support for or gzip (deflate takes preference) encodings = encodings.ToLower(); if (encodings.Contains("gzip") || encodings == "*") { Response.Filter = new GZipStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "gzip"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } else if (encodings.Contains("deflate")) { Response.Filter = new DeflateStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "deflate"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } } } } Is anyone having better success with this?

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  • How to .NET package JavaScript/bookmarklet as Interner Explorer 8/9 Plugin?

    - by Don
    How to .NET package JavaScript/bookmarklet as Interner Explorer 8/9 Plugin? I have recently finished writing JavaScript code for a browser addon, which basically (once the JS is included) runs on page-load, for given domains it then checks for certain elements in the DOM and adds new relevant elements(/information) to the page. Since the JavaScript only reads/affects the HTML DOM independently (and does not need any toolbar buttons or anything else) the JS purely needs adding to the browser's webpages. I have packaged the code to work with Firefox and Chrome and those are both working well, and I can run the code for IE in 'bookmarklet' form without problems, but I would like to learn how to package JavaScript as an actual .NET .MSI addon/plugin that will install for the current Internet Explorer 8/9. Does anyone know of a suitable guide or method I might refer to please? I have tried searching online for tutorials but most walkthroughs refer to writing the plugin body itself (which might involve unnecessary stages/includes) and are thus not regarding packing existing JS. I hope someone might have the solution please? Note: Someone packaged an old version for me as a MSI installer for Internet Explorer 7 a year ago, which installed into Program Files with a plugin.dll plugin.tlb and plugin.InstallState plus BandObjectLib.dll Interop.SHDocVw.dll and Microsoft.mshtml.dll if that is useful.

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  • Build and test on 2.2.1 iPod Touch with XCode 3.2.2?

    - by slewis
    I've just installed Xcode 3.2.2 with iPhone SDK 3.2 Beta 5 (Snow Leopard) This version of Xcode didn't come with any iPhone SDKs older than 3.0. But I want to create an app that runs on all devices from iPhone OS 2.2.1 - 3.1.3. I managed to add older SDKs into Xcode by downloading iPhone 3.1.3 with Xcode 3.1.4 and installing each 2.x SDK from the 'Packages' folder in the .dmg. So now I can select 2.2.1 as 'iPhone OS Deployment Target' and the 'Base SDK' as 3.1.3, and the app will build (thus letting me use 3.1.3 APIs with conditional coding whilst still running on 2.2.1 devices). But the problem is the app will not install and run on my 2.2.1 iPod Touch. Instead, Xcode tells me 'No provisioned iPhone OS device is connected'. If I bring up the Organizer, in the left column, the iPod Touch has an orange sphere next to it, instead of green, and clicking on this reveals: 'The version of iPhone OS on “iPod touch” is too old for use with this version of the iPhone SDK. Please restore the device to a version of the OS listed below' I'm not sure how to get this version of the SDK to support 2.2.1. (It needs to be this download of XCode/iPhone SDK because I also want it to be a universal binary so it runs on the iPad with a minimum of fuss).

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  • TypeError when using v 0.8.1 of FLOT library, but no error with v. 0.7

    - by DanielAttard
    I need some help to figure out why I am getting an error when trying to create a simple graph using the jQuery FLOT library. When I reference version 0.7 of the FLOT library, the page renders correctly: http://attardpropertytax.ca/flot07.html But when I switch to version 0.8.1 of the FLOT library, the page returns an error saying: Uncaught TypeError: Cannot read property 'left' of null http://attardpropertytax.ca/flot81.html The HTML is the same for both pages, so I cannot figure out why the new version 0.8.1 of FLOT returns an error, but the old version 0.7 does not. Any ideas? I somehow stumbled across a work-around that managed to fix my problem. I'm nut sure why, but I had to comment-out the following two sections of code from the v. 0.8.1 FLOT library: This was the first spot: // If the grid is visible, add its border width to the offset for (var a in plotOffset) { if(typeof(options.grid.borderWidth) == "object") { plotOffset[a] += showGrid ? options.grid.borderWidth[a] : 0; } else { plotOffset[a] += showGrid ? options.grid.borderWidth : 0; } } And this was the second spot: if (isNaN(v) || v < axis.min || v > axis.max // skip those lying on the axes if we got a border || (t == "full" && ((typeof bw == "object" && bw[axis.position] > 0) || bw > 0) && (v == axis.min || v == axis.max))) continue; I'm sure eventually @DNS will be taking a look at this question and maybe he will be able to help me understand what is going wrong with my code. Thanks.

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  • Convenient way to do "wrong way rebase" in git?

    - by Kaz
    I want to pull in newer commits from master into topic, but not in such a way that topic changes are replayed over top of master, but rather vice versa. I want the new changes from master to be played on top of topic, and the result to be installed as the new topic head. I can get exactly the right object if I rebase master to topic, the only problem being that the object is installed as the new head of master rather than topic. Is there some nice way to do this without manually shuffling around temporary head pointers? Edit: Here is how it can be achieved using a temporary branch head, but it's clumsy: git checkout master git checkout -b temp # temp points to master git rebase topic # topic is brought into temp, temp changes played on top Now we have the object we want, and it's pointed at by temp. git checkout topic git reset --hard temp Now topic has it; and all that is left is to tidy up by deleting temp: git branch -d temp Another way is to to do away with temp and just rebase master, and then reset topic to master. Finally, reset master back to what it was by pulling its old head from the reflog, or a cut-and-paste buffer.

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  • Serialized NHibernate Configuration objects - detect out of date or rebuild on demand?

    - by fostandy
    I've been using serialized nhibernate configuration objects (also discussed here and here) to speed up my application startup from about 8s to 1s. I also use fluent-nhibernate, so the path is more like ClassMap class definitions in code fluentconfiguration xml nhibernate configuration configuration serialized to disk. The problem from doing this is that one runs the risk of out of date mappings - if I change the mappings but forget to rebuild the serialized configuration, then I end up using the old mappings without realising it. This does not always result in an immediate and obvious error during testing, and several times the misbehaviour has been a real pain to detect and fix. Does anybody have any idea how I would be able to detect if my classmaps have changed, so that I could either issue an immediate warning/error or rebuild it on demand? At the moment I am comparing timestamps on my compiled assembly against the serialized configuration. This will pickup mapping changes, but unfortunately it generates a massive false positive rate as ANY change to the code results in an out of date flag. I can't move the classmaps to another assembly as they are tightly integrated into the business logic. This has been niggling me for a while so I was wondering if anybody had any suggestions?

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  • Using the Loader display object to load X jpegs, then resize each of the images differently while th

    - by Supernovah
    Hey there, I was wondering if this is possible to do I am able to load the image in and have it displayed easily enough by using addChild(myLoader); where myLoader is in the classWide private scope. The problem is, whenever I call my function inside that class which adds the loader to the stage, it clears the old one and puts this new one in even if I add a bit where I change myLoader.name to something related to how many images it has completed. This is a serious hinderance as I can't do anything besides KNOW how many images I will need to load and write the code X times. The problem being is that the urls are read from an XML file. My main desire was to have a classWide private Array which contained my loaders and I would assign them using myArray.push(myLoader) each time the load had completed. There is a problem which is that it compiles but they never get displayed it would work as this is written public class Images extends Sprite { private var imagesLoaded = 0; private var myLoader:Loader; ... public function Images():Void { myLoader = new Loader; //loop calling a myLoader.load(imageURL) for a bunch of urls myLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded); } public function imageLoaded { myArray[imagesLoaded] = myLoader; trace("does\'nt get to here!!"); addChild(myArray[imagesLoaded]); imagesLoaded++; } }

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  • Different standard streams per POSIX thread

    - by Roman Nikitchenko
    Is there any possibility to achieve different redirections for standard output like printf(3) for different POSIX thread? What about standard input? I have lot of code based on standard input/output and I only can separate this code into different POSIX thread, not process. Linux operation system, C standard library. I know I can refactor code to replace printf() to fprintf() and further in this style. But in this case I need to provide some kind of context which old code doesn't have. So doesn't anybody have better idea (look into code below)? #include <pthread.h> #include <stdio.h> void* different_thread(void*) { // Something to redirect standard output which doesn't affect main thread. // ... // printf() shall go to different stream. printf("subthread test\n"); return NULL; } int main() { pthread_t id; pthread_create(&id, NULL, different_thread, NULL); // In main thread things should be printed normally... printf("main thread test\n"); pthread_join(id, NULL); return 0; }

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  • Create new or update existing entity at one go with JPA

    - by Alex R
    A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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  • Which plugin framework to use for native C++/Win32

    - by Kerido
    Hi everybody. I have an extensible product that allows 3rd party developers to extend it. The aspects that can be extended are documented and interfaces are provided in the SDK. Currently, I'm using COM and I'm getting pretty comfortable with it. I especially like the ability to provide interface versioning in a unified manner. I consider it to be a requirement because you never know what you're gonna need in the future. Just to be precise, here's an example. Let's suppose I have an interface representing a particular feature: class IFeature { public: virtual void DoFeatureTask() = 0; }; Then after the interface is already documented (and someone may have used it in the plugin code) I'm realizing, I need more from this feature. Maybe, there is an option I need to provide. I just define the second version: class IFeature2 { public: virtual void DoFeatureTask(int theOption) = 0; }; I don't mean I intend to have lots of versions. But it just may happen. In COM, because every interface is associated with a GUID, I can query a preferred implementation, determine its presence, and, finally, fall back to a legacy one. But after glancing through C++/COM-related questions, I noticed many recommendations against COM. So maybe it's not the best choice and I'm just too old-school. Can you advise on an alternative?

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  • Is the size of a struct required to be an exact multiple of the alignment of that struct?

    - by Steve314
    Once again, I'm questioning a longstanding belief. Until today, I believed that the alignment of the following struct would normally be 4 and the size would normally be 5... struct example { int m_Assume_32_Bits; char m_Assume_8_Bit_Bytes; }; Because of this assumption, I have data structure code that uses offsetof to determine the distance in bytes between two adjacent items in an array. Today, I spotted some old code that was using sizeof where it shouldn't, couldn't understand why I hadn't had bugs from it, coded up a unit test - and the test surprised me by passing. A bit of investigation showed that the sizeof the type I used for the test (similar to the struct above) was an exact multiple of the alignment - ie 8 bytes. It had padding after the final member. Here is an example of why I never expected this... struct example2 { example m_Example; char m_Why_Cant_This_Be_At_Offset_6_Bytes; }; A bit of Googling showed examples that make it clear that this padding after the final member is allowed - for example http://en.wikipedia.org/wiki/Data_structure_alignment#Data_structure_padding (the "or at the end of the structure" bit). This is a bit embarrassing, as I recently posted this comment - Use of struct padding (my first comment to that answer). What I can't seem to determine is whether this padding to an exact multiple of the alignment is guaranteed by the C++ standard, or whether it is just something that is permitted and that some (but maybe not all) compilers do. So - is the size of a struct required to be an exact multiple of the alignment of that struct according to the C++ standard? If the C standard makes different guarantees, I'm interested in that too, but the focus is on C++.

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  • Boost Asio UDP retrieve last packet in socket buffer

    - by Alberto Toglia
    I have been messing around Boost Asio for some days now but I got stuck with this weird behavior. Please let me explain. Computer A is sending continuos udp packets every 500 ms to computer B, computer B desires to read A's packets with it own velocity but only wants A's last packet, obviously the most updated one. It has come to my attention that when I do a: mSocket.receive_from(boost::asio::buffer(mBuffer), mEndPoint); I can get OLD packets that were not processed (almost everytime). Does this make any sense? A friend of mine told me that sockets maintain a buffer of packets and therefore If I read with a lower frequency than the sender this could happen. ¡? So, the first question is how is it possible to receive the last packet and discard the ones I missed? Later I tried using the async example of the Boost documentation but found it did not do what I wanted. http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/tutorial/tutdaytime6.html From what I could tell the async_receive_from should call the method "handle_receive" when a packet arrives, and that works for the first packet after the service was "run". If I wanted to keep listening the port I should call the async_receive_from again in the handle code. right? BUT what I found is that I start an infinite loop, it doesn't wait till the next packet, it just enters "handle_receive" again and again. I'm not doing a server application, a lot of things are going on (its a game), so my second question is, do I have to use threads to use the async receive method properly, is there some example with threads and async receive? Thanks for you attention.

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  • Random-access archive for Unix use

    - by tylerl
    I'm looking for a good format for archiving entire file-systems of old Linux computers. TAR.GZ The tar.gz format is great for archiving files with UNIX-style attributes, but since the compression is applied across the entire archive, the design precludes random-access. Instead, if you want to access a file at the end of the archive, you have to start at the beginning and decompress the whole file (which could be several hundred GB) up to the point where you find the entry you're looking for. ZIP Conversely, one selling point of the ZIP format is that it stores an index of the archive: filenames are stored separately with pointers to the location within the archive were to find the data. If I want to extract a file at the end, I look up the position of that file by name, seek to the location, and extract the data. However, it doesn't store file attributes such as ownership, permissions, symbolic links, etc. Other options? I've tried using squashfs, but it's not really designed for this purpose. The file format is not consistent between versions, and building the archive takes a lot of time and space. What other options might suit this purpose better?

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  • Need help with strange Class#getResource() issue

    - by Andreas_D
    I have some legacy code that reads a configuration file from an existing jar, like: URL url = SomeClass.class.getResource("/configuration.properties"); // some more code here using url variable InputStream in = url.openStream(); Obviously it worked before but when I execute this code, the URL is valid but I get an IOException on the third line, saying it can't find the file. The url is something like "file:jar:c:/path/to/jar/somejar.jar!configuration.properties" so it doesn't look like a classpath issue - java knows pretty well where the file can be found.. The above code is part of an ant task and it fails while the task is executed. Strange enough - I copied the code and the jar file into a separate class and it works as expected, the properties file is readable. At some point I changed the code of the ant task to URL url = SomeClass.class.getResource("/configuration.properties"); // some more code here using url variable InputStream in = SomeClass.class.getResourceAsStream("/configuration.properties"); and now it works - just until it crashes in another class where a similiar access pattern is implemented.. Why could it have worked before, why does it fail now? The only difference I see at the moment is, that the old build was done with java 1.4 while I'm trying it with Java 6 now. Workaround Today I installed Java 1.4.2_19 on the build server and made ant to use it. To my totally frustrating surprise: The problem is gone. It looks to me, that java 1.4.2 can handle URLs of this type while Java 1.6 can't (at least in my context/environment). I'm still hoping for an explanation although I'm facing the work to rewrite parts of the code to use Class#getRessourceAsStream which behaved much more stable...

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  • How to check for mip-map availability in OpenGL?

    - by Xavier Ho
    Recently I bumped into a problem where my OpenGL program would not render textures correctly on a 2-year-old Lenovo laptop with an nVidia Quadro 140 card. It runs OpenGL 2.1.2, and GLSL 1.20, but when I turned on mip-mapping, the whole screen is black, with no warnings or errors. This is my texture filter code: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); After 40 minutes of fiddling around, I found out mip-mapping was the problem. Turning it off fixed it: // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); I get a lot of aliasing, but at least the program is visible and runs fine. Finally, two questions: What's the best or standard way to check if mip-mapping is available on a machine, aside from checking OpenGL versions? If mip-mapping is not available, what's the best work-around to avoid aliasing?

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