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• Using awk to return only certain chunks of data

  - by Koriar

  I'm not 100% certain how to phrase my question simply, so I apologize if this has been answered somewhere and I was just unable to find it. What I have are debug logs with authentication packets in them along with a bunch of other output. I need to search through about 2 million lines of logs to find every packet that contains a certain mac address. The packets look something like this (slightly censored): -----------------[ header ]----------------- Event: Authd-Response (1900) Sequence: -54 Timestamp: 1969-12-31 19:30:00 (0) ---------------[ attributes ]--------------- Auth-Result = Auth-Accept Service-Profile-SID = 53 Service-Profile-SID = 49 RADIUS-Access-Accept-Attr/WiMAX-Capability = 0x(numbers) Session-Timeout = 3600 Service-Profile-SID = 4 Service-Profile-SID = 29 Chargeable-User-Identity = "(Numbers)" User-Password = "(the MAC address I'm looking for)" -------------------------------------------- However there are about 10 different possible types with different possible lengths. They all start with the header line and end with the all-dashes line. I've had success using awk to get the code blocks themselves using this: awk '/-----------------\[ header \]-----------------/,/--------------------------------------------/' filename.txt But I was hoping to be able to use it to return only the packets which contain the MAC address that I need. I've been trying to figure this out for a few days now and I'm pretty stuck. I could try and write a bash script, but I could swear that I've used awk to do something like this before...

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• What are some commonly used source code check-in policies?

  - by rwmnau

  I'm curious what code review policies other development shops apply to their source code when it's checked into the source control repository. I'm setting up a TFS (Team Foundation) server, and I'd like to apply some check-in policies to start to stamp out bad practices. For example, I was thinking of starting with the following couple, so this is the kind of stuff I'm looking for: Prohibit empty "Catch" blocks. This would prevent applications from swallowing any exceptions without at least requiring a comment explaining why it's not necessary to do anything with the exception. Prohibit "Catch ex as Exception" generic exception handling. Instead, require code to catch specific types of exceptions and deal with them appropriately, instead of just building catch-all handling. Require a check-in comment. This one should be self-explanatory, though it seems that TFS (and most other source-control systems) don't require a comment by default. While these are just examples, they're where I'm thinking of starting, and while I'd like some additional examples of what's popular, I'm open to feedback on these. Also, though we're a mostly .NET shop, I imagine the popular policies are universal across languages and IDEs (we have some Java development and a few people who will use the repository develop with Eclipse).

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• Using Maven for maintaining product documentation

  - by Waldheinz

  We are using Maven for building a Java server-style application. It consists of several modules (in a single Maven "reactor") which can be plugged together to generate a final product (essentially a .jar) with the features enabled that the customer needs. All the internals are documented using JavaDoc and all, but that's not what you can give to the customer to find out how to get the thing running. Currently we have an OpenOffice document which serves as end-user documentation. I'd like to integrate this documentation into the Maven build process where each module's documentation is maintained (hand-edited) together with the Module's sources and the final document can reference the required Module documentation sections, add some friendly foreword and, if possible at all, can reference into the JavaDocs. Ultimately, the document should be output as a PDF. Is there any experience on Maven plugins can help with this? Is DocBook the right tool? Maybe Latex? Or something completely different? A sound "stick with OpenOffice and some text blocks" could be an answer, too.

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• In Perl, how can I wait for threads to end in parallel?

  - by Pmarcoen

  I have a Perl script that launches 2 threads,one for each processor. I need it to wait for a thread to end, if one thread ends a new one is spawned. It seems that the join method blocks the rest of the program, therefore the second thread can't end until everything the first thread does is done which sort of defeats its purpose. I tried the is_joinable method but that doesn't seem to do it either. Here is some of my code : use threads; use threads::shared; @file_list = @ARGV; #Our file list $nofiles = $#file_list + 1; #Real number of files $currfile = 1; #Current number of file to process my %MSG : shared; #shared hash $thr0 = threads->new(\&process, shift(@file_list)); $currfile++; $thr1 = threads->new(\&process, shift(@file_list)); $currfile++; while(1){ if ($thr0->is_joinable()) { $thr0->join; #check if there are files left to process if($currfile <= $nofiles){ $thr0 = threads->new(\&process, shift(@file_list)); $currfile++; } } if ($thr1->is_joinable()) { $thr1->join; #check if there are files left to process if($currfile <= $nofiles){ $thr1 = threads->new(\&process, shift(@file_list)); $currfile++; } } } sub process{ print "Opening $currfile of $nofiles\n"; #do some stuff if(some condition){ lock(%MSG); #write stuff to hash } print "Closing $currfile of $nofiles\n"; } The output of this is : Opening 1 of 4 Opening 2 of 4 Closing 1 of 4 Opening 3 of 4 Closing 3 of 4 Opening 4 of 4 Closing 2 of 4 Closing 4 of 4

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• Should frontend and backend be handled by different controllers?

  - by DR

  In my previous learning projects I always used a single controller, but now I wonder if that is good practice or even always possible. In all RESTful Rails tutorials the controllers have a show, an edit and an index view. If an authorized user is logged on, the edit view becomes available and the index view shows additional data manipulation controls, like a delete button or a link to the edit view. Now I have a Rails application which falls exactly into this pattern, but the index view is not reusable: The normal user sees a flashy index page with lots of pictures, complex layout, no Javascript requirement, ... The Admin user index has a completly different minimalistic design, jQuery table and lots of additional data, ... Now I'm not sure how to handle this case. I can think of the following: Single controller, single view: The view is split into two large blocks/partials using an if statement. Single controller, two views: index and index_admin. Two different controllers: BookController and BookAdminController None of these solutions seems perfect, but for now I'm inclined to use the 3rd option. What's the preferred way to do this?

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• java number exceeds long.max_value - how to detect?

  - by jurchiks

  I'm having problems detecting if a sum/multiplication of two numbers exceeds the maximum value of a long integer. Example code: long a = 2 * Long.MAX_VALUE; System.out.println("long.max * smth > long.max... or is it? a=" + a); This gives me -2, while I would expect it to throw a NumberFormatException... Is there a simple way of making this work? Because I have some code that does multiplications in nested IF blocks or additions in a loop and I would hate to add more IFs to each IF or inside the loop. Edit: oh well, it seems that this answer from another question is the most appropriate for what I need: http://stackoverflow.com/a/9057367/540394 I don't want to do boxing/unboxing as it adds unnecassary overhead, and this way is very short, which is a huge plus to me. I'll just write two short functions to do these checks and return the min or max long. Edit2: here's the function for limiting a long to its min/max value according to the answer I linked to above: /** * @param a : one of the two numbers added/multiplied * @param b : the other of the two numbers * @param c : the result of the addition/multiplication * @return the minimum or maximum value of a long integer if addition/multiplication of a and b is less than Long.MIN_VALUE or more than Long.MAX_VALUE */ public static long limitLong(long a, long b, long c) { return (((a > 0) && (b > 0) && (c <= 0)) ? Long.MAX_VALUE : (((a < 0) && (b < 0) && (c >= 0)) ? Long.MIN_VALUE : c)); } Tell me if you think this is wrong.

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• Programmatically parse and edit C++ Source Files

  - by Kryten

  Hi, I want to able programmatically parse and edit C++ source files. I need to be able to change/add code in certain sections of code (i.e. in functions, class blocks, etc). I would also (preferably) be able to get comments as well. Part of what I want to do can be explained by the following piece of code: CPlusPlusSourceParser cp = new CPlusPlusSourceParser(“x.cpp”); // Create C++ Source Parser Object CPlusPlusSourceFunction[] funcs = cp.getFunctions(); // Get all the functions for (int i = 0; i &lt funcs.length; i++) { // Loop through all functions funcs[i].append(/* … code I want to append …*/); // Append some code to function } cp.save(); // Save new source cp.close(); // Close file How can I do that? I’d like to be able to do this preferably in Java, C++, Perl, Python or C#. However, I am open to other language API’s.

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• Modules vs. Classes and their influence on descendants of ActiveRecord::Base

  - by Chris

  Here's a Ruby OO head scratcher for ya, brought about by this Rails scenario: class Product < ActiveRecord::Base has_many(:prices) # define private helper methods end module PrintProduct attr_accessor(:isbn) # override methods in ActiveRecord::Base end class Book < Product include PrintProduct end Product is the base class of all products. Books are kept in the products table via STI. The PrintProduct module brings some common behavior and state to descendants of Product. Book is used inside fields_for blocks in views. This works for me, but I found some odd behavior: After form submission, inside my controller, if I call a method on a book that is defined in PrintProduct, and that method calls a helper method defined in Product, which in turn calls the prices method defined by has_many, I'll get an error complaining that Book#prices is not found. Why is that? Book is a direct descendant of Product! More interesting is the following.. As I developed this hierarchy PrintProduct started to become more of an abstract ActiveRecord::Base, so I thought it prudent to redefine everything as such: class Product < ActiveRecord::Base end class PrintProduct < Product end class Book < PrintProduct end All method definitions, etc. are the same. In this case, however, my web form won't load because the attributes defined by attr_accessor (which are "virtual attributes" referenced by the form but not persisted in the DB) aren't found. I'll get an error saying that there is no method Book#isbn. Why is that?? I can't see a reason why the attr_accessor attributes are not found inside my form's fields_for block when PrintProduct is a class, but they are found when PrintProduct is a Module. Any insight would be appreciated. I'm dying to know why these errors are occurring!

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• Thread synchronization and aborting.

  - by kubal5003

  Hello, I've got a little problem with ending the work of one of my threads. First things first so here's the app "layout": Thread 1 - worker thread (C++/CLI) - runs and terminates as expected for(...) { try { if(TabuStop) return; System::Threading::Monitor::Enter("Lock1"); //some work, unmanaged code } finally { if(stop) { System::Threading::Monitor::Pulse("Lock1"); } else { System::Threading::Monitor::Pulse("Lock1"); System::Threading::Monitor::Wait("Lock1"); } } } Thread 2 - display results thread (C#) while (WorkerThread.IsAlive) { lock ("Lock1") { if (TabuEngine.TabuStop) { Monitor.Pulse("Lock1"); } else { Dispatcher.BeginInvoke(RefreshAction); Monitor.Pulse("Lock1"); Monitor.Wait("Lock1", 5000); } } // Thread.Sleep(5000); } I'm trying to shut the whole thing down from app main thread like this: TabuEngine.TabuStop = true; //terminates nicely the worker thread and if (DisplayThread.IsAlive) { DisplayThread.Abort(); } I also tried using DisplayThread.Interrupt, but it always blocks on Monitor.Wait("Lock1", 5000); and I can't get rid of it. What is wrong here? How am I supposed to perform the synchronization and let it do the work that it is supposed to do? //edit I'm not even sure now if the trick with using "Lock1" string is really working and locks are placed on the same object..

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• When is a try catch not a try catch?

  - by Dearmash

  I have a fun issue where during application shutdown, try / catch blocks are being seemingly ignored in the stack. I don't have a working test project (yet due to deadline, otherwise I'd totally try to repro this), but consider the following code snippet. public static string RunAndPossiblyThrow(int index, bool doThrow) { try { return Run(index); } catch(ApplicationException e) { if(doThrow) throw; } return ""; } public static string Run(int index) { if(_store.Contains(index)) return _store[index]; throw new ApplicationException("index not found"); } public static string RunAndIgnoreThrow(int index) { try { return Run(index); } catch(ApplicationException e) { } return ""; } During runtime this pattern works famously. We get legacy support for code that relies on exceptions for program control (bad) and we get to move forward and slowly remove exceptions used for program control. However, when shutting down our UI, we see an exception thrown from "Run" even though "doThrow" is false for ALL current uses of "RunAndPossiblyThrow". I've even gone so far as to verify this by modifying code to look like "RunAndIgnoreThrow" and I'll still get a crash post UI shutdown. Mr. Eric Lippert, I read your blog daily, I'd sure love to hear it's some known bug and I'm not going crazy. EDIT This is multi-threaded, and I've verified all objects are not modified while being accessed

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• Extend legacy site with another server-side programming platform best practice

  - by Andrew Florko

  Company I work for have a site developed 6-8 years ago by a team that was enthusiastic enough to use their own private PHP-based CMS. I have to put dynamic data from one intranet company database on this site in one week: 2-3 pages. I contacted company site administrator and she showed me administrative part - CMS allows only to insert html blocks & manage site map (site is deployed on machine that is inside company & fully accessible & upgradeable). I'm not a PHP-guy & I don't want to dive into legacy hardly-who-ever-heard-about CMS engine I also don't want to contact developers team, 'cos I'm not sure they are still present and capable enough to extend this old days site and it'll take too much time anyway. I am about to deploy helper asp.net site on IIS with 2-3 pages required & refer helper site via iframe from present site. New pages will allow to download some dynamic content from present site also. Is it ok and what are the pitfalls with iframe approach?

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• Implementing client callback functionality in WCF

  - by PoweredByOrange

  The project I'm working on is a client-server application with all services written in WCF and the client in WPF. There are cases where the server needs to push information to the client. I initially though about using WCF Duplex Services, but after doing some research online, I figured a lot of people are avoiding it for many reasons. The next thing I thought about was having the client create a host connection, so that the server could use that to make a service call to the client. The problem however, is that the application is deployed over the internet, so that approach requires configuring the firewall to allow incoming traffic and since most of the users are regular users, that might also require configuring the router to allow port forwarding, which again is a hassle for the user. My third option is that in the client, spawns a background thread which makes a call to the GetNotifications() method on server. This method on the server side then, blocks until an actual notification is created, then the thread is notified (using an AutoResetEvent object maybe?) and the information gets sent to the client. The idea is something like this: Client private void InitializeListener() { Task.Factory.StartNew(() => { while (true) { var notification = server.GetNotifications(); // Display the notification. } }, CancellationToken.None, TaskCreationOptions.LongRunning, TaskScheduler.Default); } Server public NotificationObject GetNotifications() { while (true) { notificationEvent.WaitOne(); return someNotificationObject; } } private void NotificationCreated() { // Inform the client of this event. notificationEvent.Set(); } In this case, NotificationCreated() is a callback method called when the server needs to send information to the client. What do you think about this approach? Is this scalable at all?

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• RequestBuilder timeouts and browser connection limits per domain.

  - by WesleyJohnson

  This is specifically about GWT's RequestBuilder, but should apply to general XHR as well. My company is having me build a near realtime chat application over HTTP. Yes, I do realize there are better ways to do chat aplications, but this is what they want. Eventually we want it working on the iPad/iPhone as well so flash is out, which rules out websockets and comet as well, I think? Anyway, I'm running into issues were I've set GWT's RequestBuilder timeout to 10 seconds and we get very random and sporadic timeouts. We've got error handling and emailing on the server side and never get any errors, which suggests the underlying XHR request that RequestBuilder is built on, never gets to the server and times out after 10 seconds. We're using these request to poll the server for new messages rather often and also for sending new messages to the server and also polling (less frequently) for other parts of application. What I'm afraid of is that we're running into the browsers limit on concurrent connections to the same domain (2 for IE by default?). Now my question is - If I construct a RequestBuilder and call it's send() method and the browser blocks it from sending until one of the 2 connections per domain is free, does the timeout still start while the request is being blocked or will it not start until the browser actually releases the underlying XHR? I hope that's clear, if not please let me know and I'll try to explain more.

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• Split UInt32 (audio frame) into two SInt16s (left and right)?

  - by morgancodes

  Total noob to anything lower-level than Java, diving into iPhone audio, and realing from all of the casting/pointers/raw memory access. I'm working with some example code wich reads a WAV file from disc and returns stereo samples as single UInt32 values. If I understand correctly, this is just a convenient way to return the 32 bits of memory required to create two 16 bit samples. Eventually this data gets written to a buffer, and an audio unit picks it up down the road. Even though the data is written in UInt32-sized chunks, it eventually is interpreted as pairs of 16-bit samples. What I need help with is splitting these UInt32 frames into left and right samples. I'm assuming I'll want to convert each UInt32 into an SInt16, since an audio sample is a signed value. It seems to me that for efficiency's sake, I ought to be able to simply point to the same blocks in memory, and avoid any copying. So, in pseudo-code, it would be something like this: UInt32 myStereoFrame = getFramefromFilePlayer; SInt16* leftChannel = getFirst16Bits(myStereoFrame); SInt16* rightChannel = getSecond16Bits(myStereoFrame); Can anyone help me turn my pseudo into real code?

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• In C/C++ mode in Emacs, change face of code in #if 0...#endif block to comment face

  - by pogopop77

  I'm trying to add functionality found in some other code editors to my Emacs configuration, whereby C/C++ code within #if 0...#endif blocks is automatically set to the comment face/font. Based on my testing, cpp-highlight-mode does something like what I want, but requires user action. It seems like tying into the font-lock functionality is the correct option to make the behavior automatic. I have successfully followed examples in the GNU documentation to change the face of single-line regular expressions. For example: (add-hook 'c-mode-common-hook (lambda () (font-lock-add-keywords nil '(("\\<\\(FIXME\\|TODO\\|HACK\\|fixme\\|todo\\|hack\\)" 1 font-lock-warning-face t))))) works fine to highlight debug related keywords anywhere in a file. However, I am having problems matching #if 0...#endif as a multiline regular expression. I found some useful information in this post (How to compose region like ""), that suggested that Emacs must be told specifically to allow for multiline matches. But this code: (add-hook 'c-mode-common-hook (lambda () '(progn (setq font-lock-multiline t) (font-lock-add-keywords nil '(("#if 0\\(.\\|\n\\)*?#endif" 1 font-lock-comment-face t)))))) still does not work for me. Perhaps my regular expression is wrong (though it appears to work using M-x re-builder), I've messed up my syntax, or I'm following the wrong approach entirely. I'm using Aquamacs 2.1 (which is based on GNU Emacs 23.2.50.1) on OS X 10.6.5, if that makes a difference. Any assistance would be appreciated!

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• Is this mingw bug ?

  - by Debanjan

  Hi, I have been trying to execute this program on my migw ,through code::blocks, #include <string.h> #include <math.h> #include <stdio.h> #define N 100 int p[N / 64]; int pr[N]; int cnt; void sieve() { int i,j; for(i=0;i<N;i++) pr[i]=1; pr[0]=pr[1]=0; for(i=2;i<N;i++) if(pr[i]) { p[cnt]=i; cnt++; for(j=i+i;j<=N;j+=i) pr[j]=0; } } int main(){ sieve(); int i; for(i=0;i<cnt;i++) printf("%d ",p[i]); puts(""); printf("Total number of prime numbers : %d",cnt); return 0; } In My system the output is : 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 Total number of prime numbers : 22 Which is completely insane,since I am completely sure about the implementation of my algorithm. So I decided to try it in Ideone where it gives correct output.Can anybody point out the reason ?

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• Lite-Javascript Gallery - Can I position the img absolutely in relationship to the lis?

  - by blackessej

  I have a lite-javascript run image gallery. The javascript grabs each element in the list and places it as a background in the parent element. Then the CSS styles the thumbnails as small blocks with a defined height/width. A click-event for each object toggles it’s child’s element’s visibility and adds an “active” class name to the . Using CSS, I'm trying to place the absolutely to make it appear at the same position for each thumb, but it's moving in relation to the thumbs. Here's the CSS: #jgal li { background-position:50% 50%; background-repeat:no-repeat; border:solid #999 4px; cursor:pointer; display:block; float:left; height:60px; width:60px; margin-bottom:14px; margin-right:14px; opacity:0.5; } #jgal li img { position:absolute; top:0px; left:210px; display:none; } And the site: http://www.erisdesigns.net Thanks in advance for any help!

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• My kernel only works in block (0,0)

  - by ZeroDivide

  I am trying to write a simple matrixMultiplication application that multiplies two square matrices using CUDA. I am having a problem where my kernel is only computing correctly in block (0,0) of the grid. This is my invocation code: dim3 dimBlock(4,4,1); dim3 dimGrid(4,4,1); //Launch the kernel; MatrixMulKernel<<<dimGrid,dimBlock>>>(Md,Nd,Pd,Width); This is my Kernel function __global__ void MatrixMulKernel(int* Md, int* Nd, int* Pd, int Width) { const int tx = threadIdx.x; const int ty = threadIdx.y; const int bx = blockIdx.x; const int by = blockIdx.y; const int row = (by * blockDim.y + ty); const int col = (bx * blockDim.x + tx); //Pvalue stores the Pd element that is computed by the thread int Pvalue = 0; for (int k = 0; k < Width; k++) { Pvalue += Md[row * Width + k] * Nd[k * Width + col]; } __syncthreads(); //Write the matrix to device memory each thread writes one element Pd[row * Width + col] = Pvalue; } I think the problem may have something to do with memory but I'm a bit lost. What should I do to make this code work across several blocks?

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• How Many States Does an Activity Have?

  - by Android Eve

  The Activity lifecycle section in the Application Fundamentals tutorial states that there are 3 states: An activity has essentially three states: (1. active/running 2. paused 3. stopped) But then as I continued reading the actual Activity class documentation, the Activity Lifecycle section states that there are 4 state: An activity has essentially four states: (1. active/running 2. paused 3. stopped 4. "dropped"?) Both sources (on the same website) agree about the first 3, but the 4th one is only mentioned in the class documentation and is unnamed. So, are there really 4 states or only 3? If there are 4, what is the name of the 4th one? Please help me understand this discrepancy. Also, highlighted colored blocks in this beautiful and very informative flowchart don't seem to correspond to the states. Where, in the flowchart, would you mark the 3 or 4 states?

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• PDF search on the iPhone

  - by pt2ph8

  After two days trying to read annotations from a PDF using Quartz, I've managed to do it and posted my code. Now I'd like to do the same for another frequently asked question: searching PDF documents with Quartz. Same situation as before, this question has been asked many times with almost no practical answers. So I need some pointers first, as I still haven't implemented this myself. What I tried: I tried using CGPDFScannerScan handling the TJ and Tj operators - returns the right text on some PDF, whereas on other documents it returns mostly random letters. Maybe it's related to text encoding? Someone pointed out that text blocks (marked by BT/ET operators) should be handled instead, but I still haven't managed to do so. Anyone managed to extract text from any PDF? After that, searching should be easy by storing all the text in a NSMutableString and using rangeOfString (if there's a better way please let me know). But then how to highlight the result? I know there are a few operators to find the glyph sizes, so I could calculate the resulting rect based on those values, but I've been reading the spec for hours... it's a bloated mess and I'm going insane. Anyone with a practical explanation? Thanks.

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• Need help with height 100% layout

  - by serg

  I am trying to build the following layout (file browser type of thing, left block would contain a list of files, right panel would contain selected file content): <------------- MENU -------------------> <--- LEFT ----><------- RIGHT ---------> <--- LEFT ----><------- RIGHT ---------> <--- LEFT ----><------- RIGHT ---------> <--- LEFT ----><------- RIGHT ---------> <--- LEFT ----><------- RIGHT ---------> <--- LEFT ----><------- RIGHT ---------> The page itself shouldn't have any scrollbars. Menu has 100% width and fixed height Left block has fixed width and 100% height. If content is taller - scroll bar appears inside the left block only. Right block contains <pre> element and takes the remaining width and 100% height. If content is wider or taller - scrollbar appears inside the right block only. This is what I have so far: http://jsbin.com/uqegi4/3/edit The problem is fixed menu height messes up 100% height calculation and all scrollbars inside left and right blocks appear at wrong time. I don't care about cross browser compatibility, only Chrome matters. Thanks.

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• local vs core contoller

  - by latvian

  Hi, I am adding new column and action in the local admin app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php which works fine, however. The local controller/app/code/local/Mage/Adminhtml/Block/Catalog/Product.php is not being used or is not overloading the admin one /app/code/core/Mage/Adminhtml/Block/Catalog/Product.php. This is almost fresh install of Magento 1.4.0.1. I am the only one working, so i know it is not overloaded by some custom controller. I have disabled all custom modules. I have rolled back most of my changes. I have checked /etc/Modules/Mage_Catalog.xml. Refreshed cache all possible ways, loged in and out. Nothing....still using the core contoller copy. why? How do you troubleshoot, meaning, at what moment magento decides using between core or local copies? ...its even more strange because it does not parse local Adminhtml config.xml but uses local Adminthml copy of Blocks. Any pointer would help. I would like to keep everything in local code. Thank You, Margots

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• How to limit TCP writes to particular size and then block untlil the data is read

  - by ustulation

  {Qt 4.7.0 , VS 2010} I have a Server written in Qt and a 3rd party client executable. Qt based server uses QTcpServer and QTcpSocket facilities (non-blocking). Going through the articles on TCP I understand the following: the original implementation of TCP mentioned the negotiable window size to be a 16-bit value, thus maximum being 65535 bytes. But implementations often used the RFC window-scale-extension that allows the sliding window size to be scalable by bit-shifting to yield a maximum of 1 gigabyte. This is implementation defined. This could have resulted in majorly different window sizes on receiver and sender end as the server uses Qt facilities without hardcoding any window size limit. Client 1st asks for all information it can based on the previous messages from the server before handling the new (accumulating) incoming messages. So at some point Server receives a lot of messages each asking for data of several MB's. This the server processes and puts it into the sender buffer. Client however is unable to handle the messages at the same pace and it seems that client’s receiver buffer is far smaller (65535 bytes maybe) than sender’s transmit window size. The messages thus get accumulated at sender’s end until the sender’s buffer is full too after which the TCP writes on sender would block. This however does not happen as sender buffer is much larger. Hence this manifests as increase in memory consumption on the sender’s end. To prevent this from happening, I used Qt’s socket’s waitForBytesWritten() with timeout set to -1 for infinite waiting period. This as I see from the behaviour blocks the thread writing TCP data until the data has actually been sensed by the receiver’s window (which will happen when earlier messages have been processed by the client at application level). This has caused memory consumption at Server end to be almost negligible. is there a better alternative to this (in Qt) if i want to restrict the memory consumption at server end to say x MB's? Also please point out if any of my understandings is incorrect.

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• Computation overhead in C# - Using getters/setters vs. modifying arrays directly and casting speeds

  - by Jeffrey Kern

  I was going to write a long-winded post, but I'll boil it down here: I'm trying to emulate the graphical old-school style of the NES via XNA. However, my FPS is SLOW, trying to modify 65K pixels per frame. If I just loop through all 65K pixels and set them to some arbitrary color, I get 64FPS. The code I made to look-up what colors should be placed where, I get 1FPS. I think it is because of my object-orented code. Right now, I have things divided into about six classes, with getters/setters. I'm guessing that I'm at least calling 360K getters per frame, which I think is a lot of overhead. Each class contains either/and-or 1D or 2D arrays containing custom enumerations, int, Color, or Vector2D, bytes. What if I combined all of the classes into just one, and accessed the contents of each array directly? The code would look a mess, and ditch the concepts of object-oriented coding, but the speed might be much faster. I'm also not concerned about access violations, as any attempts to get/set the data in the arrays will done in blocks. E.g., all writing to arrays will take place before any data is accessed from them. As for casting, I stated that I'm using custom enumerations, int, Color, and Vector2D, bytes. Which data types are fastest to use and access in the .net Framework, XNA, XBox, C#? I think that constant casting might be a cause of slowdown here. Also, instead of using math to figure out which indexes data should be placed in, I've used precomputed lookup tables so I don't have to use constant multiplication, addition, subtraction, division per frame. :)

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• How am i overriding this C++ inherited member function without the virtual keyword being used?

  - by Gary Willoughby

  I have a small program to demonstrate simple inheritance. I am defining a Dog class which is derived from Mammal. Both classes share a simple member function called ToString(). How is Dog overriding the implementation in the Mammal class, when i'm not using the virtual keyword? (Do i even need to use the virtual keyword to override member functions?) mammal.h #ifndef MAMMAL_H_INCLUDED #define MAMMAL_H_INCLUDED #include <string> class Mammal { public: std::string ToString(); }; #endif // MAMMAL_H_INCLUDED mammal.cpp #include <string> #include "mammal.h" std::string Mammal::ToString() { return "I am a Mammal!"; } dog.h #ifndef DOG_H_INCLUDED #define DOG_H_INCLUDED #include <string> #include "mammal.h" class Dog : public Mammal { public: std::string ToString(); }; #endif // DOG_H_INCLUDED dog.cpp #include <string> #include "dog.h" std::string Dog::ToString() { return "I am a Dog!"; } main.cpp #include <iostream> #include "dog.h" using namespace std; int main() { Dog d; std::cout << d.ToString() << std::endl; return 0; } output I am a Dog! I'm using MingW on Windows via Code::Blocks.

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