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  • Given a main function and a cleanup function, how (canonically) do I return an exit status in Bash/Linux?

    - by Zac B
    Context: I have a bash script (a wrapper for other scripts, really), that does the following pseudocode: do a main function if the main function returns: $returncode = $? #most recent return code if the main function runs longer than a timeout: kill the main function $returncode = 140 #the semi-canonical "exceeded allowed wall clock time" status run a cleanup function if the cleanup function returns an error: #nonzero return code exit $? #exit the program with the status returned from the cleanup function else #cleanup was successful .... Question: What should happen after the last line? If the cleanup function was successful, but the main function was not, should my program return 0 (for the successful cleanup), or $returncode, which contains the (possibly nonzero and unsuccessful) return code of the main function? For a specific application, the answer would be easy: "it depends on what you need the script for." However, this is more of a general/canonical question (and if this is the wrong place for it, kill it with fire): in Bash (or Linux in general) programming, do you typically want to return the status that "means" something (i.e. $returncode) or do you ignore such subjectivities and simply return the code of the most recent function? This isn't Bash-specific: if I have a standalone executable of any kind, how, canonically should it behave in these cases? Obviously, this is somewhat debatable. Even if there is a system for these things, I'm sure that a lot of people ignore it. All the same, I'd like to know. Cheers!

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  • Should I use a regular server instead of AWS?

    - by Jon Ramvi
    Reading about and using the Amazon Web Services, I'm not really able to grasp how to use it correctly. Sorry about the long question: I have a EC2 instance which mostly does the work of a web server (apache for file sharing and Tomcat with Play Framework for the web app). As it's a web server, the instance is running 24/7. It just came to my attention that the data on the EC2 instance is non persistent. This means I lose my database and files if it's stopped. But I guess it also means my server settings and installed applications are lost as they are just files in the same way as the other data. This means that I will either have to rewrite the whole app to use amazon CloudDB or write some code which stores the db on S3 and make my own AMI with the correct applications installed and configured. Or can this be quick-fixed by using EBS somehow? My question is 1. is my understanding of aws is correct? and 2. is it's worth it? It could be a possibility to just set up a regular dedicated server where everything is persistent, as you would expect. Would love to have the scaleability of aws though..

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  • How are you using C++0x today? [closed]

    - by Roger Pate
    This is a question in two parts, the first is the most important and concerns now: Are you following the design and evolution of C++0x? What blogs, newsgroups, committee papers, and other resources do you follow? Even where you're not using any new features, how have they affected your current choices? What new features are you using now, either in production or otherwise? The second part is a follow-up, concerning the new standard once it is final: Do you expect to use it immediately? What are you doing to prepare for C++0x, other than as listed for the previous questions? Obviously, compiler support must be there, but there's still co-workers, ancillary tools, and other factors to consider. What will most affect your adoption? Edit: The original really was too argumentative; however, I'm still interested in the underlying question, so I've tried to clean it up and hopefully make it acceptable. This seems a much better avenue than duplicating—even though some answers responded to the argumentative tone, they still apply to the extent that they addressed the questions, and all answers are community property to be cleaned up as appropriate, too.

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  • ASP.net MVC Linq-To-SQL Many-To-Many Field Binding

    - by user336858
    Hi there, The short version of this question is "Is there a way to gracefully handle database insertion for an object that has a many-to-many field that has been set up in a partial class?" Apologies if it's been asked before. Example Suppose I have a typical MVC setup with the tables: Posts {PostID, ...} Categories {CategoryID, ...} A post can have more than one category, and a category can identify more than one post. Thus suppose further that I need an extra table: PostCategories {PostID, CategoryID, ...} This handles the many-to-many relationship between posts and categories. As far as I know, there's no way to do this in Linq-to-SQL right now so I have to shoehorn it in by adding a partial Post class to the project to add that functionality. Something like: public partial class Post { public IEnumerable<Category> Categories{ get { ... } set { ... } } } So I can now create a "Create" view that automatically populates a "Categories" UI item. This is where the trouble starts. So here's my question: How do you get automatic object model binding to work cleanly with an object that has a many-to-many relationship to control? The workaround that makes many-to-many relationships possible relies on the Post object having a PostID in order to be associated with CategoryID(s), which is only issued after the Post object has been submitted for validation and insertion. Bit of a Catch22 here. Any terminology, links, or tips you can provide would be tremendously helpful!

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  • Fast, easy, and secure method to perform DB actions with GET

    - by rob - not a robber
    Hey All, Sort of a methods/best practices question here that I am sure has been addressed, yet I can't find a solution based on the vague search terms I enter. I know starting off the question with "Fast and easy" will probably draw out a few sighs, so my apologies. Here is the deal. I have a logged in area where an ADMIN can do a whole host of POST operations to input data relating to their profile. The way I have data structured is pretty distinct and well segmented in most tables as it relates to the ID of the admin. Now, I have a table where I dump one type of data into and differentiate this data by assigning the ADMIN's unique ID to each record. In other words, all ADMINs have this one type of data writing to this table. I just differentiate by the ADMIN ID with each record. I was planning on letting the ADMIN remove these records by clicking on a link with a query string - obviously using GET. Obviously, the query structure is in the link so any logged in admin could then exploit the URL and delete a competitor's records. Is the only way to safely do this through POST or should I pass through the session info that includes password and validate it against the ADMIN ID that is requesting the delete? This is obviously much more work for me. As they said in the auto repair biz I used to work in... there are 3 ways to do a job: Fast, Good, and Cheap. You can only have two at a time. Fast and cheap will not be good. Good and cheap will not have fast turnaround. Fast and good will NOT be cheap. haha I guess that applies here... can never have Fast, Easy and Secure all at once ;) Thanks in advance...

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  • Moving from a non-clustered PK to a clustered PK in SQL 2005

    - by adaptr
    HI all, I recently asked this question in another thread, and thought I would reproduce it here with my solution: What if I have an auto-increment INT as my non-clustered primary key, and there are about 15 foreign keys defined to it ? (snide comment about original designer being braindead in the original :) ) This is a 15M row table, on a live database, SQL Standard, so dropping indexes is out of the question. Even temporarily dropping the foreign key constraints will be difficult. I'm curious if anybody has a solution that causes minimal downtime. I tested this in our testing environment and finally found that the downtime wasn't as severe as I had originally feared. I ended up writing a script that drops all FK constraints, then drops the non-clustered key, re-creates the PK as a clustered index, and finally re-created all FKs WITH NOCHECK to avoid trawling through all FKs to check constraint compliance. Then I just enable the CHECK constraints to enable constraint checking from that point onwards, and all is dandy :) The most important thing to realize is that during the time the FKs are absent, there MUST NOT be any INSERTs or DELETEs on the parent table, as this may break the constraints and cause issues in the future. The total time taken for clustering a 15M row, 800MB index was ~4 minutes :)

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  • How to set margin for inner controls of WrapPanel

    - by Andrey Tagaew
    Hi Guys! I'm new in WPF and have a question. Here is an example that I'm using: <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <StackPanel> <WrapPanel Orientation="Horizontal" > <Button Content="test1" Margin="10,0" Padding="10,10" /> <Button Content="test2" Margin="10,0" Padding="10,10" /> <Button Content="test3" Margin="10,0" Padding="10,10" /> <Button Content="test4" Margin="10,0" Padding="10,10" /> <Button Content="test5" Margin="10,0" Padding="10,10" /> </WrapPanel> </StackPanel> As you can see, my wrap panel has several buttons. Each button has the same margin and padding. The question is, is there a way of setting margin and padding for wrap panel, so each element inside the wrap panel may use it values? This make the code shorter and let me specify Margin and Padding only one time instead of setting it for each control in the panel. Thank you!

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  • Finding character in String in Vector.

    - by SoulBeaver
    Judging from the title, I kinda did my program in a fairly complicated way. BUT! I might as well ask anyway xD This is a simple program I did in response to question 3-3 of Accelerated C++, which is an awesome book in my opinion. I created a vector: vector<string> countEm; That accepts all valid strings. Therefore, I have a vector that contains elements of strings. Next, I created a function int toLowerWords( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) transform( vec[loop].begin(), vec[loop].end(), vec[loop].begin(), ::tolower ); that splits the input into all lowercase characters for easier counting. So far, so good. I created a third and final function to actually count the words, and that's where I'm stuck. int counter( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) for( int secLoop = 0; secLoop < vec[loop].size(); secLoop++ ) { if( vec[loop][secLoop] == ' ' ) That just looks ridiculous. Using a two-dimensional array to call on the characters of the vector until I find a space. Ridiculous. I don't believe that this is an elegant or even viable solution. If it was a viable solution, I would then backtrack from the space and copy all characters I've found in a separate vector and count those. My question then is. How can I dissect a vector of strings into separate words so that I can actually count them? I thought about using strchr, but it didn't give me any epiphanies.

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  • Determining polygon intersection and containment

    - by Victor Liu
    I have a set of simple (no holes, no self-intersections) polygons, and I need to check that they don't intersect each other (one can be entirely contained in another; that is okay). I can check this by simply checking the per-vertex inside-ness of one polygon versus other polygons. I also need to determine the containment tree, which is the set of relationships that say which polygon contains any given polygon. Since no polygon can intersect any other, then any contained polygon has a unique container; the "next-bigger" one. In other words, if A contains B contains C, then A is the parent of B, and B is the parent of C, and we don't consider A the parent of C. The question: How do I efficiently determine the containment relationships and check the non-intersection criterion? I ask this as one question because maybe a combined algorithm is more efficient than solving each problem separately. The algorithm should take as input a list of polygons, given by a list of their vertices. It should produce a boolean B indicating if none of the polygons intersect any other polygon, and also if B = true, a list of pairs (P, C) where polygon P is the parent of child C. This is not homework. This is for a hobby project I am working on.

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  • Can't get screen pixel from a specific full screen game with any language?

    - by user1007059
    Okay, I know this might seem like I'm posting a duplicate question since I've asked something similar like a day ago HOWEVER, if anyone sees any problem with this, please read my question first before judging: Yesterday I tried getting a specific pixel from a fullscreen game in C#. I thought my C# code was faulty but when I tried with multiple full screen games today they all worked except for that specific game. I literally tried with 10 different full screen games, a couple being mmofps, mmorpg, mmotps, regular rpg games, regular shooters, regular action adventure games, etc. I tried with multiple programming languages, and with every game except that specific game I'm dealing with, it returns the pixel color to me like I wanted. So let me explain what I tried: first I tried returning an IntPtr with C# using GetDC(IntPtr.Zero) before invoking GetPixel(int x, int y) and then getting the color out of it. Then I tried using the Robot class in Java and using the getPixelColor(int x, int y) method. I also tried using GetDC(0) to return an HDC object in C++ and then invoking GetPixel(int x, int y) before again extracting the color. These three methods worked EXACTLY the same in every single game except that specific game I was talking about. They returned the pixel perfectly, and extracted the exact same color perfectly. I don't feel it's necessary to tell you the game name or anything, since you probably don't even know it, but what could possibly be causing this malfunction in 1 specific game? PS: The game ALWAYS returns an RGB color of: A = 255, R = 0, G = 0, B = 0. Also, I tried taking a snapshot of the game with the 3 programming languages, and then getting the pixel which actually works in all 3 languages, but since I need to get this pixel every 30 ms, it kind of makes my game lag a bit (+ I think it takes up a lot of memory)

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  • File descriptor limits and default stack sizes

    - by Charles
    Where I work we build and distribute a library and a couple complex programs built on that library. All code is written in C and is available on most 'standard' systems like Windows, Linux, Aix, Solaris, Darwin. I started in the QA department and while running tests recently I have been reminded several times that I need to remember to set the file descriptor limits and default stack sizes higher or bad things will happen. This is particularly the case with Solaris and now Darwin. Now this is very strange to me because I am a believer in 0 required environment fiddling to make a product work. So I am wondering if there are times where this sort of requirement is a necessary evil, or if we are doing something wrong. Edit: Great comments that describe the problem and a little background. However I do not believe I worded the question well enough. Currently, we require customers, and hence, us the testers, to set these limits before running our code. We do not do this programatically. And this is not a situation where they MIGHT run out, under normal load our programs WILL run out and seg fault. So rewording the question, is requiring the customer to change these ulimit values to run our software to be expected on some platforms, ie, Solaris, Aix, or are we as a company making it to difficult for these users to get going? Bounty: I added a bounty to hopefully get a little more information on what other companies are doing to manage these limits. Can you set these pragmatically? Should we? Should our programs even be hitting these limits or could this be a sign that things might be a bit messy under the covers? That is really what I want to know, as a perfectionist a seemingly dirty program really bugs me.

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  • How to handle image/gif type response on client side using GWT

    - by user200340
    Hi all, I have a question about how to handle image/gif type response on client side, any suggestion will be great. There is a service which responds for retrieving image (only one each time at the moment) from database. The code is something like, JDBC Connection Construct MYSQL query. Execute query If has ResultSet, retrieve first one { //save image into Blob image, “img” is the only entity in the image table. image = rs.getBlob("img"); } response.setContentType("image/gif"); //set response type InputStream in = image.getBinaryStream(); //output Blob image to InputStream int bufferSize = 1024; //buffer size byte[] buffer = new byte[bufferSize]; //initial buffer int length =0; //read length data from inputstream and store into buffer while ((length = in.read(buffer)) != -1) { out.write(buffer, 0, length); //write into ServletOutputStream } in.close(); out.flush(); //write out The code on client side .... imgform.setAction(GWT.getModuleBaseURL() + "serviceexample/ImgRetrieve"); .... ClickListener { OnClick, then imgform.submit(); } formHandler { onSubmit, form validation onSubmitComplete ??????? //handle response, and display image **Here is my question, i had tried Image img = new Image(GWT.getHostPageBaseURL() +"serviceexample/ImgRetrieve"); mg.setSize("300", "300"); imgpanel.add(img); but i only got a non-displayed image with 300X300 size.** } So, how should i handle the responde in this case? Thanks,

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  • An online php debugger/code editor

    - by Zirak
    It's a simple deal: I'm sometimes in places where I don't have my laptop, and find myself with spare time and an idea for a project. But unfortunately, I can't do anything about it. I tried a variety of solutions, which include running IDEs (like phpstorm or Aptana) on a disc-on-key or cd (very slow and unappealing), trying several online solutions (like http://phpanywhere.net) and found that all of them are either buggy, overloaded or underloaded with features, just difficult to use, require FTP etc etc. All that is required here is a syntax highlighting and debugging alerts; no actual running of code. So the question is split into two: 1)Do you know of a good online php editor that you've used and enjoyed? 2)If no, then how would you go about making one? The second one seems a bit general, so I'll try and expand...It might be a good idea; if you can't find one, make one. The question is about the concept of making a syntax highlighter (shouldn't be too difficult), and the difficult part of catching php errors WITHOUT executing any php code. Thank you in advance.

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  • Performance difference in for loop condition?

    - by CSharperWithJava
    Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm not a beginner to coding by any means, but I've never bothered with the comma operator. Are there performance/behavior differences or is it purely aesthetic? One last note, I know there are bigger performance fish to fry than a conditional operator, but I'm just curious. Indulge me. Edit Thanks for your answers. It turns out the code that prompted this question had misused the comma operator in the way I've described. I wondered what the difference was and why it wasn't a && operator, but it was just written incorrectly. I didn't think anything was wrong with it because it worked just fine. Thanks for straightening me out.

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  • Design: How to declare a specialized memory handler class

    - by Michael Dorgan
    On an embedded type system, I have created a Small Object Allocator that piggy backs on top of a standard memory allocation system. This allocator is a Boost::simple_segregated_storage< class and it does exactly what I need - O(1) alloc/dealloc time on small objects at the cost of a touch of internal fragmentation. My question is how best to declare it. Right now, it's scope static declared in our mem code module, which is probably fine, but it feels a bit exposed there and is also now linked to that module forever. Normally, I declare it as a monostate or a singleton, but this uses the dynamic memory allocator (where this is located.) Furthermore, our dynamic memory allocator is being initialized and used before static object initialization occurs on our system (as again, the memory manager is pretty much the most fundamental component of an engine.) To get around this catch 22, I added an extra 'if the small memory allocator exists' to see if the small object allocator exists yet. That if that now must be run on every small object allocation. In the scheme of things, this is nearly negligable, but it still bothers me. So the question is, is there a better way to declare this portion of the memory manager that helps decouple it from the memory module and perhaps not costing that extra isinitialized() if statement? If this method uses dynamic memory, please explain how to get around lack of initialization of the small object portion of the manager.

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  • Declaration, allocation and assignment of an array of pointers to function pointers

    - by manneorama
    Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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  • Coding Practices which enable the compiler/optimizer to make a faster program.

    - by EvilTeach
    Many years ago, C compilers were not particularly smart. As a workaround K&R invented the register keyword, to hint to the compiler, that maybe it would be a good idea to keep this variable in an internal register. They also made the tertiary operator to help generate better code. As time passed, the compilers matured. They became very smart in that their flow analysis allowing them to make better decisions about what values to hold in registers than you could possibly do. The register keyword became unimportant. FORTRAN can be faster than C for some sorts of operations, due to alias issues. In theory with careful coding, one can get around this restriction to enable the optimizer to generate faster code. What coding practices are available that may enable the compiler/optimizer to generate faster code? Identifying the platform and compiler you use, would be appreciated. Why does the technique seem to work? Sample code is encouraged. Here is a related question [Edit] This question is not about the overall process to profile, and optimize. Assume that the program has been written correctly, compiled with full optimization, tested and put into production. There may be constructs in your code that prohibit the optimizer from doing the best job that it can. What can you do to refactor that will remove these prohibitions, and allow the optimizer to generate even faster code? [Edit] Offset related link

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  • HOWTO: implement a jQuery version of ASP.Net MVC "Strongly Typed Partial Views"

    - by Sam Carleton
    I am working on a multi-page assessment form where the questions/responses are database driven. Currently I the basic system working with Html.BeginForm via standard ASP.Net MVC. At this point in time, the key to the whole system is the 'Strongly Typed Partial Views'. When the question/response is read from the database, the response type determines which derived model is created and added to the collection. The main view it iterates through the collection and uses the 'Strongly Typed Partial Views' system of ASP.Net MVC to determine which view to render the correct type of response (radio button, drop down, or text box). I would like to change this process from a Html.BeginForm to Ajax.BeginForm. The problem is I don't have a clue as to how to implement the dynamic creation of the question/response in the JavaScript/jQuery world. Any thoughts and/or suggestions? Here is the current code to generate the dynamic form: @using (Html.BeginForm(new { mdsId = @Model.MdsId, sectionId = @Model.SectionId })) { <div class="SectionTitle"> <span>Section @Model.SectionName - @Model.SectionDescription</span> <span style="float: right">@Html.CheckBoxFor(x => x.ShowUnansweredQuestions) Show only unaswered questions</span> </div> @Html.HiddenFor(x => x.PrevSectionId) @Html.HiddenFor(x => x.NextSectionId) for (var i = 0; i < Model.answers.Count(); i++) { @Html.EditorFor(m => m.answers[i]); } }

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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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  • C# parameter count mismatch when trying to add AsyncCallback into BeginInvoke()

    - by PunX
    I have main form (PrenosForm) and I am trying to run Form2 asynchronously. It works without callback delegate: this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. Doesn't work with callback delegate (parameter count mismatch): this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count mismatch 2. Works with callback delegate if I do it like this: cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. My question is why does one way work and the other doesn't? I'm new at this. Would anyone be so kind as to answer my question and point out my mistakes? private delegate void copyDelegat(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt); private delegate void callBackDelegat(IAsyncResult a); public void doCopy(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt) { new Form2(datoteke, path, forma, efekt); } public void callBackFunc(IAsyncResult a) { AsyncResult res = a.AsyncState as AsyncResult; copyDelegat delegat = res.AsyncDelegate as copyDelegat; delegat.EndInvoke(a); } public void kopiraj(List<ListViewItem> datoteke, DragDropEffects efekt) { copyDelegat cp = new copyDelegat(doCopy); callBackDelegat callBackDelegate = new callBackDelegat(callBackFunc); this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count missmatch 2. this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. }

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  • Event feed implementation - will it scale?

    - by SlappyTheFish
    Situation: I am currently designing a feed system for a social website whereby each user has a feed of their friends' activities. I have two possible methods how to generate the feeds and I would like to ask which is best in terms of ability to scale. Events from all users are collected in one central database table, event_log. Users are paired as friends in the table friends. The RDBMS we are using is MySQL. Standard method: When a user requests their feed page, the system generates the feed by inner joining event_log with friends. The result is then cached and set to timeout after 5 minutes. Scaling is achieved by varying this timeout. Hypothesised method: A task runs in the background and for each new, unprocessed item in event_log, it creates entries in the database table user_feed pairing that event with all of the users who are friends with the user who initiated the event. One table row pairs one event with one user. The problems with the standard method are well known – what if a lot of people's caches expire at the same time? The solution also does not scale well – the brief is for feeds to update as close to real-time as possible The hypothesised solution in my eyes seems much better; all processing is done offline so no user waits for a page to generate and there are no joins so database tables can be sharded across physical machines. However, if a user has 100,000 friends and creates 20 events in one session, then that results in inserting 2,000,000 rows into the database. Question: The question boils down to two points: Is this worst-case scenario mentioned above problematic, i.e. does table size have an impact on MySQL performance and are there any issues with this mass inserting of data for each event? Is there anything else I have missed?

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  • Corrupt UTF-8 Characters with PHP 5.2.10 and MySQL 5.0.81

    - by jkndrkn
    We have an application hosted on both a local development server and a live site. We are experiencing UTF-8 corruption issues and are looking to figure out how to resolve them. The system is run using symfony 1.0 with Propel. On our development server, we are running PHP 5.2.0 and MySQL 5.0.32. We do not experience corrupted UTF-8 characters there. On our live site, PHP 5.2.10 and MySQL 5.0.81 is running. On that server, certain characters such as ô´ and S are corrupted once they are stored in the database. The corrupted characters are showing up as either question marks or approximations of the original character with adjacent question marks. Examples of corruption: Uncorrupted: ô´ Corrupted: ô? Uncorrupted: S Corrupted: ? We are currently using the following techniques on both development and live servers: Executing the following queries prior to execution of any other queries: SET NAMES 'utf8' COLLATE 'utf8_unicode_ci' SET CHARSET 'utf8' Setting the <meta> Content-Type value to: <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> Adding the following to our .htaccess file: AddDefaultCharset utf-8 Using mb_* (multibyte) PHP functions where necessary. Being sure to set database columns to use utf8_unicode_ci collation. These techniques are sufficient for our development site, but do not work on the live site. On the live site I've also tried adding mysql_set_encoding('ut8', $mysql_connection) but this does not help either. I have found some evidence that newer versions of PHP and MySQL are mishandling UTF-8 character encodings.

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  • how do i implement / build / create an 'in memory database' for my unit test

    - by Michel
    Hi all, i've started unit testing a while ago and as turned out i did more regression testing than unit testing because i also included my database layer thus going to the database verytime. So, implemented Unity to inject a fake database layer, but i of course want to store some data, and the main opinion was: "create an in-memory database" But what is that / how do i implement that? Main question is: i think i have to fake the database layer, but doesn't that make me create a 'simple database' myself or: how can i keep it simple and not rebuilding Sql Server just for my unit tests :) At the end of this question i'll give an explanation of the situation i got in on the project i just started on, and i was wondering if this was the way to go. Michel Current situation i've seen at this client is that testdata is contained in XML files, and there is a 'fake' database layer that connects all the xml files together. For the real database we're using the entity framework, and this works very simple. And now, in the 'fake' layer, i have top create all kind of classes to load, save, persist etc. the data. It sounds weird that there is so much work in the fake layer, and so little in the real layer. I hope this all makes sense :)

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  • Impersonate SYSTEM (or equivalent) from Administrator Account

    - by KevenK
    This question is a follow up and continuation of this question about a Privilege problem I'm dealing with currently. Problem Summary: I'm running a program under a Domain Administrator account that does not have Debug programs (SeDebugPrivilege) privilege, but I need it on the local machine. Klugey Solution: The program can install itself as a service on the local machine, and start the service. Said service now runs under the SYSTEM account, which enables us to use our SeTCBPrivilege privilege to create a new access token which does have SeDebugPrivilege. We can then use the newly created token to re-launch the initial program with the elevated rights. I personally do not like this solution. I feel it should be possible to acquire the necessary privileges as an Administrator without having to make system modifications such as installing a service (even if it is only temporary). I am hoping that there is a solution that minimizes system modifications and can preferably be done on the fly (ie: Not require restarting itself). I have unsuccessfully tried to LogonUser as SYSTEM and tried to OpenProcessToken on a known SYSTEM process (such as csrss.exe) (which fails, because you cannot OpenProcess with PROCESS_TOKEN_QUERY to get a handle to the process without the privileges I'm trying to acquire). I'm just at my wit's end trying to come up with an alternative solution to this problem. I was hoping there was an easy way to grab a privileged token on the host machine and impersonate it for this program, but I haven't found a way. If anyone knows of a way around this, or even has suggestions on things that might work, please let me know. I really appreciate the help, thanks!

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  • release object of a return method object c

    - by Piero
    in run the app with the analyze build, and Xcode found me a lot of memory leak and there is one in particular that i don't know how solve here it is: - (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section { UIImageView *sectionImage = [[UIImageView alloc] init]; if (section == 0)sectionImage.image = [UIImage imageNamed:@"myImage.png"]; return sectionImage; } so my question is, how i can release this sectionImage? if is the return of the method? EDIT: i have another question, analyze give me another memory leak, i have this: .h @property (nonatomic, retain) NSIndexPath *directCellPath; .m @synthesize directCellPath = _directCellPath; - (id)init{ if ((self = [super initWithNibName:@"MyViewController" bundle:nil])) { self.directCellPath = [[NSIndexPath alloc] init]; } return self; } then in the code i use it and finally in the dealloc i do this: - (void)dealloc { [_directCellPath release]; [super dealloc]; } and give me a memory leak on this line: self.directCellPath = [[NSIndexPath alloc] init]; why if i have deallocated it in the dealloc?

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