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• Load Spikes on a Apache MySQL Server with Wordpress MU

  - by Vikram Goyal

  Hi there, I am trying to investigate the reasons for some mysterious load spikes on a Linux Apache server (2.2.14) running PHP 5.2.9 on a dedicated server with enough processing power and memory. My primary web application is a Wordpress MU (2.9.2) installation. I have investigated and ruled out DOS attack, MySQL or Apache configuration issues. The log files don't give me anything of interest, except to tell me that there is severe load. The load (which can go up to 100) just seems to come and go. It helps that I have a script that checks every 3 minutes for the load, and restarts Apache. Restarting it helps, and the server comes back, till it happens again. There seems to be no set time frame, or visitor numbers on the site that can trigger this. Even a low number of concurrent visitors (20) can trigger it. I am almost convinced that there is a rewrite loop somewhere that is causing Apache to go mad. Apache is trying to serve something that is causing it to spawn more and more processes till it keels over. My question is: Given that I am convinced that this is a rewrite issue or something similar, how can I try and figure out what the issue is? What should I monitor? Apache logs are voluminous, and not very helpful. Of course, if this is not the issue, then at least knowing what to look for will help me eliminate this as an issue and look for something else. Thanks! Vikram

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• How to extract a 2x2 submatrix from a bigger matrix

  - by ZaZu

  Hello, I am a very basic user and do not know much about commands used in C, so please bear with me...I cant use very complicated codes. I have some knowledge in the stdio.h and ctype.h library, but thats about it. I have a matrix in a txt file and I want to load the matrix based on my input of number of rows and columns For example, I have a 5 by 5 matrix in the file. I want to extract a specific 2 by 2 submatrix, how can I do that ? I created a nested loop using : FILE *sample sample=fopen("randomfile.txt","r"); for(i=0;i<rows;i++){ for(j=0;j<cols;j++){ fscanf(sample,"%f",&matrix[i][j]); } fscanf(sample,"\n",&matrix[i][j]); } fclose(sample); Sadly the code does not work .. If I have this matrix : 5.00 4.00 5.00 6.00 5.00 4.00 3.00 25.00 5.00 3.00 4.00 23.00 5.00 2.00 352.00 6.00 And inputting 3 for row and 3 for column, I get : 5.00 4.00 5.00 6.00 5.00 4.00 3.00 25.00 5.00 Not only this isnt a 2 by 2 submatrix, but even if I wanted the first 3 rows and first 3 columns, its not printing it correctly.... I need to start at row 3 and col 3, then take the 2 by 2 submatrix ! I should have ended up with : 4.00 23.00 352.00 6.00 I heard that I can use fgets and sscanf to accomplish this. Here is my trial code : fgets(garbage,1,fin); sscanf(garbage,"\n"); But this doesnt work either :( What am I doing wrong ? Please help. Thanks !

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• Recursion Problems in Prolog

  - by Humble_Student

  I'm having some difficulties in prolog, I'm trying to write a predicate that will return all paths between two cities, although at the moment it returns the first path it finds on an infinite loop. Not sure where I'm going wrong but I've been trying to figure this out all day and I'm getting nowhere. Any help that could be offered would be appreciated. go:- repeat, f([],0,lon,spa,OP,OD), write(OP), write(OD), fail. city(lon). city(ath). city(spa). city(kol). path(lon,1,ath). path(ath,3,spa). path(spa,2,kol). path(lon,1,kol). joined(X,Y,D):- path(X,D,Y);path(Y,D,X). f(Ci_Vi,Di,De,De,PaO,Di):- append([De],Ci_Vi,PaO), !. f(Cities_Visited,Distance,Start,Destination,Output_Path,Output_Distance):- repeat, city(X), joined(Start,X,D), not_member(X,Cities_Visited), New_Distance is Distance + D, f([Start|Cities_Visited],New_Distance,X,Destination,Output_Path,Output_Distance). not_member(X,List):- member(X,List), !, fail. not_member(X,List). The output I'm expecting here is [spa,ath,lon]4 [spa,kol,lon]3. Once again, any help would be appreciated. Many thanks in advance.

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• In IIS6, how to provide authenticated access to static files on remote server

  - by frankadelic

  We have a library of ZIP files that we would like to make available for download at an ASP.NET site. The files are sitting on a NAS device that is accessible from out web farm. Here is our initial strategy: Map an IIS virtual directory to the shared drive at path /zipfiles Users can download the zip files when given the URL However, if users share links to the files, anyone can download them. We would instead like to make use of the ASP.NET forms authentication in our site to validate users' requests before initiating the file transfer. A few problems: A request for a zip file is handled by IIS, not ASP.NET. So it is not subject to forms authentication. In addition, we don't want ASP.NET to handle the request, because it uses up an ASP.NET thread and is not scalable for download of large files. So, configuring the asp.net dll to handle *.zip requests is not an option. Any ideas on this? One idea we've tossed around is this: Initial request for download will be for an ashx handler. This handler will, after authentication, generate a download token which is saved to a database. Then, the user is redirected to the file with token appended in QueryString (e.g. /files/xyz.zip?token=123456789). An ISAPI plugin will be used to check the token. Also, the token will expire after x amount of time. Any thoughts on this? I have not implemented an ISAPI plugin so I'm not sure if this will even work. I would like to avoid custom coding since security is an issue and I'd prefer to use a time-tested solution.

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• Practical rules for premature optimization

  - by DougW

  It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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• How to populate data from .txt file into Excel in VBA?

  - by swei

  I'm trying to create something to read data from a .txt file, then populate data into .xls, but after open the .txt file, how do I get the data out? Basically I'm trying to get the the third column of the lines dated '04/06/2010'. After I open the .txt file, when I use ActiveSheet.Cells(row, col), the ActiveSheet is not pointing to .txt file. My .txt file is like this (space delimited): 04/05/10 23 29226 04/05/10 24 26942 04/06/10 1 23166 04/06/10 2 22072 04/06/10 3 21583 04/06/10 4 21390 Here is the code I have: Dim BidDate As Date BidDate = '4/6/2010' Workbooks.OpenText Filename:=ForecastFile, StartRow:=1, DataType:=xlDelimited, Space:=True If Err.Number = 1004 Then MsgBox ("The forecast file " & ForecastFile & " was not found.") Exit Sub End If On Error GoTo 0 Dim row As Integer, col As Integer row = 1 col = 1 cell_value = activeSheet.Cells(row, col) MsgBox ("the cell_value=" & cell_value) Do While (cell_value <> BidDate) And (cell_value <> "") row = row + 1 cell_value = activeSheet.Cells(row, col) ' MsgBox ("the value is " & cell_value) Loop If cell_value = "" Then MsgBox ("A load forecast for " & BidDate & " was not found in your current load forecast file titled '" + ForecastFile + ". " + "Make sure you have a load forecast for the current bid date and then open this spreadsheet again.") ActiveWindow.Close Exit Sub End If Can anyone point out where it goes wrong here?

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• How do I assert that two arbitrary type objects are equivalent, without requiring them to be equal?

  - by Tomas Lycken

  To accomplish this (but failing to do so) I'm reflecting over properties of an expected and actual object and making sure their values are equal. This works as expected as long as their properties are single objects, i.e. not lists, arrays, IEnumerable... If the property is a list of some sort, the test fails (on the Assert.AreEqual(...) inside the for loop). public void WithCorrectModel<TModelType>(TModelType expected, string error = "") where TModelType : class { var actual = _result.ViewData.Model as TModelType; Assert.IsNotNull(actual, error); Assert.IsInstanceOfType(actual, typeof(TModelType), error); foreach (var prop in typeof(TModelType).GetProperties()) { Assert.AreEqual(prop.GetValue(expected, null), prop.GetValue(actual, null), error); } } If dealing with a list property, I would get the expected results if I instead used CollectionAssert.AreEquivalent(...) but that requires me to cast to ICollection, which in turn requries me to know the type listed, which I don't (want to). It also requires me to know which properties are list types, which I don't know how to. So, how should I assert that two objects of an arbitrary type are equivalent? Note: I specifically don't want to require them to be equal, since one comes from my tested object and one is built in my test class to have something to compare with.

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• Multi-dimensional array edge/border conditions

  - by kirbuchi

  Hi, I'm iterating over a 3 dimensional array (which is an image with 3 values for each pixel) to apply a 3x3 filter to each pixel as follows: //For each value on the image for (i=0;i<3*width*height;i++){ //For each filter value for (j=0;j<9;j++){ if (notOutsideEdgesCondition){ *(**(outArray)+i)+= *(**(pixelArray)+i-1+(j%3)) * (*(filter+j)); } } } I'm using pointer arithmetic because if I used array notation I'd have 4 loops and I'm trying to have the least possible number of loops. My problem is my notOutsideEdgesCondition is getting quite out of hands because I have to consider 8 border cases. I have the following handled conditions Left Column: ((i%width)==0) && (j%3==0) Right Column: ((i-1)%width ==0) && (i>1) && (j%3==2) Upper Row: (i<width) && (j<2) Lower Row: (i>(width*height-width)) && (j>5) and still have to consider the 4 corner cases which will have longer expressions. At this point I've stopped and asked myself if this is the best way to go because If I have a 5 line long conditional evaluation it'll not only be truly painful to debug but will slow the inner loop. That's why I come to you to ask if there's a known algorithm to handle this cases or if there's a better approach for my problem. Thanks a lot.

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• iphone crash log with dSym not loading debug information

  - by AngeDeLaMort

  Hello, I was trying to see why my application crashed on the device (iPhone) using the dSym generated along the executable (in ad hoc), but I don't know why, there isn't any useful information. It seems that "Organizer" is able to find the appropriate dSym and translate some data into more readable one, but when it comes to my application, I just have an address. Since I know how to reproduce it, I've tried to setup my build so it can help me in the future. So, I've tried to find if I had all the proper flags set int the project build properties and everything seems fine. So after doing some research, it seems that all information are stripped during link time and the dSym seems completely useless. I've played with some flags, but nothing changed. So, is there something special to do in order to get the crash file human readable? Or is it impossible in the ad hoc setting? The closest thing near to work that I've done was to build a debug version and look up the address in it. At least it seems to give the right file. So, I made a sample app and here what I have: (the line I want is #4): Thread 0 Crashed: 0 libobjc.A.dylib 0x00003ebc objc_msgSend + 20 1 UIKit 0x0005c970 -[UIView dealloc] + 60 2 UIKit 0x0005c840 -[UIImageView dealloc] + 76 3 CoreFoundation 0x0003963a -[NSObject release] + 28 4 MyApplication 0x000046a6 0x1000 + 13990 5 UIKit 0x00069750 -[UIViewController view] + 44 6 MyApplication 0x000053fa 0x1000 + 17402 The crash is made using 2 successive releases on an object. Thanks in advance.

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• How does the PHP IteratorIterator class work?

  - by WilliamMartin

  Try as I might I cannot get my head around what the IteratorIterator class actually does. I understand that classes can implement Traversable so the engine knows it can loop using foreach and I realise that IteratorIterator is supposed to convert anything that is Traversable into an Iterator but I cannot for the life of me understand how. Take for example, the PDOStatement class; how would the standard Iterator methods (next, key, rewind, etc) be implemented to allow iteration over a PDOStatement? Sorry if my question is unclear, I am just struggling to grasp the exact reason for this class and the documentation on it is scant. Thanks, Will Update: Going through the phpt files, I found one test which uses IteratorIterator: <?php $root = simplexml_load_string('<?xml version="1.0"?> <root> <child>Hello</child> <child>World</child> </root> '); foreach (new IteratorIterator($root->child) as $child) { echo $child."\n"; } ?> The expected output is: Hello World I don't really follow how the IteratorIterator construct takes $root-child as an argument and how it manages to iterate over the child elements.

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• here is my code in Jquery and Asp.net Unable to get a correct ANS as I am getting from jquery?

  - by ricky roy

  unable to get the correct Ans as i am getting from the Jquery I am using jquery.countdown.js here is my code [WebMethod] public static String GetTime() { DateTime dt = new DateTime(); dt = Convert.ToDateTime("April 9, 2010 22:38:10"); return dt.ToString("dddd, dd MMMM yyyy HH:mm:ss"); } html file <script type="text/javascript" src="Scripts/jquery-1.3.2.js"></script> <script type="text/javascript" src="Scripts/jquery.countdown.js"></script> <script type="text/javascript"> $(function() { var shortly = new Date('April 9, 2010 22:38:10'); var newTime = new Date('April 9, 2010 22:38:10'); //for loop divid /// $('#defaultCountdown').countdown({ until: shortly, onExpiry: liftOff, onTick: watchCountdown, serverSync: serverTime }); $('#div1').countdown({ until: newTime }); }); function serverTime() { var time = null; $.ajax({ type: "POST", //Page Name (in which the method should be called) and method name url: "Default.aspx/GetTime", // If you want to pass parameter or data to server side function you can try line contentType: "application/json; charset=utf-8", dataType: "json", data: "{}", async: false, //else If you don't want to pass any value to server side function leave the data to blank line below //data: "{}", success: function(msg) { //Got the response from server and render to the client time = new Date(msg.d); alert(time); }, error: function(msg) { time = new Date(); alert('1'); } }); return time; } function watchCountdown() { } function liftOff() { } </script>

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• Grouping a list of of entities which has a sublist in c#

  - by mikei

  I have a set of Entities which basically has this structure. {Stats Name="<Product name> (en)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} {Stats Name="<Product name> (us)" TotalResources="10" ..} {DayStats Date="2009-12-10" TotalResources="5"} {DayStats Date="2009-12-11" TotalResources="5"} {Stats} ... What I wan't to extract from this set is a new set entities (or entity in the example above) where the first level has been grouped by the (ignoring the country label) where all/some of the properties has been summmed together, including the the sublist of {DayStas} on a per day basis. So the result set of the example would look something like this: {Stats Name="<Product name>" TotalResources="20" ..} {DayStats Date="2009-12-10" TotalResources="10"} {DayStats Date="2009-12-11" TotalResources="10"} {Stats} ... So my question is: Is it possible to do this in a more elegant way in LINQ rather than the vanilla "loop-trhough-each-entity-and-compare"-way? And I wan't the set to contain the same type of entities as the original set ({Stats}, {DayStats}), your answer doesn't need to include code for that, I can probably work that out by myself. Just letting you know incase you need to take that into account. (I'm sorry if this question has been discussed before, I tried searching to no avail. I guess my searching skills are fuubar ;)) Merry christmas =)

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• C++ LPTSTR to int (but memory overwrite problem using atoi)

  - by Dexter

  I have the following code, m_edit is a MFC CEdit (I know I would never use MFC but project demanded it). It's a simple loop, that gets the text from a text edit, converts it to integer after getting the first line, then stores it in m_y vector. LPTSTR szTemp; vector<int> m_y; for(int i = 0; i < m_edit->GetLineCount(); i++){ szTemp = s_y.GetBuffer(0); m_edit->GetLine(i, szTemp); // get line text store in szTemp y = atoi(szTemp); m_y.push_back(y); szTemp = ""; y = 0; } IMPORTANT EXAMPLE: So let's say the CEdit has 6 numbers: 0 5 2 5 18 6 If you use Visual Studio's debugger you will notice an anomaly!! Here's what it shows: y = 0 y = 5 y = 2 y = 5 y = 18 y = 68 Do you see that? szTemp when inserted into atoi, it returns the number 6, but concatenates the 2nd digit of the last number!!! This is why I did szTemp = "";, but the problem persists. Also, let's say the last number was 17 (not 18), then this time debugger would say y = 67, so it is definitely this problem. However, Visual Studio debugger, when you hover over szTemp during this iteration, it says '6' <--- not '68' inside szTemp. So somehow atoi is ruining it. Am I suppose to concatenate a \0 into szTemp before putting it into atoi? How do I solve this easily?

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• How to get a fully transparent backbuffer in directx 9 without vista Desktop Window Manager

  - by flawlesslyfaulted

  I currently have an activex control that initiates a media (video/audio) framework another development group in my company developed and I am providing a window handle to that code. That handle is being used by their rendering plugin in the pipeline that uses Direct3d for rendering the video using that handle. I have seperate LPDIRECT3D9EX and LPDIRECT3DDEVICE9EX pointers that I initialize in my activex control. I am trying to clear a backbuffer to transparent and then use directx drawing primatives to draw on that backbuffer producing a transparent window with my drawing primatives over the streaming video on the directx surface below. It appears that clearing a device backbuffer with full alpha transparency is ignored by directx. d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_RGBA(0, 0, 1, 0 /*full alpha*/), 1.0f, 0); I can see the object I draw but they are drawn on top of a backbuffer that has the RGB color specified without the alpha value. The project linked (http://www.codeproject.com/KB/directx/umvistad3d.aspx) to in the stackoverflow question below does what I want but requires vista's Desktop Window Manager and won't work for XP. http://stackoverflow.com/questions/148275/how-do-i-draw-transparent-directx-content-in-a-transparent-window I have tried with D3DRS_ALPHABLENDENABLE true with configured blend with no avail. I have also tried to have pixels with full alpha values not rendered using D3DRS_ALPHATESTENABLE, D3DRS_ALPHAREF, and D3DRS_ALPHAFUNC setup but this doesn't work either. I have tried using ColorFill with alpha after retrieving the backbuffer with GetBackBuffer but this doesn't work either. (again only RGB is used) Finally I have tried creating a texture, selecting a surface, colorfilling that surface with a fully transparent alpha value, then loading that surface onto the backbuffer but only the RGB values appear to be used. I have checked the capabilities using the DXCapsViewer.exe and the D3DFMT_A8R8G8B8 backbuffer format that I am using for the backbuffer is valid so it can't be that. Has anyone gotten a transparent backbuffer in directx to work in XP?

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• Reducing Time Complexity in Java

  - by Koeneuze

  Right, this is from an older exam which i'm using to prepare my own exam in january. We are given the following method: public static void Oorspronkelijk() { String bs = "Dit is een boodschap aan de wereld"; int max = -1; char let = '*'; for (int i=0;i<bs.length();i++) { int tel = 1; for (int j=i+1;j<bs.length();j++) { if (bs.charAt(j) == bs.charAt(i)) tel++; } if (tel > max) { max = tel; let = bs.charAt(i); } } System.out.println(max + " keer " + let); } The questions are: what is the output? - Since the code is just an algorithm to determine the most occuring character, the output is "6 keer " (6 times space) What is the time complexity of this code? Fairly sure it's O(n²), unless someone thinks otherwise? Can you reduce the time complexity, and if so, how? Well, you can. I've received some help already and managed to get the following code: public static void Nieuw() { String bs = "Dit is een boodschap aan de wereld"; HashMap<Character, Integer> letters = new HashMap<Character, Integer>(); char max = bs.charAt(0); for (int i=0;i<bs.length();i++) { char let = bs.charAt(i); if(!letters.containsKey(let)) { letters.put(let,0); } int tel = letters.get(let)+1; letters.put(let,tel); if(letters.get(max)<tel) { max = let; } } System.out.println(letters.get(max) + " keer " + max); } However, I'm uncertain of the time complexity of this new code: Is it O(n) because you only use one for-loop, or does the fact we require the use of the HashMap's get methods make it O(n log n) ? And if someone knows an even better way of reducing the time complexity, please do tell! :)

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• Poor DB4O performance - What am I doing wrong?

  - by Jon

  I read Rob Conery's post about Object databases and thought I'd give it a go. I have a class lets say Book with 15 properties mostly string, some int, one Datetime and 2 decimals. I used Rob's code to open the database file etc to test on a Winforms project not a Web project. So I did the following: for(int i = 0; i < 1000000; i++) { var Book = new Book(); //Assign variables s.Save(Book); } s.CommitChanges(); This took at least a couple of minutes. I then tried to retrieve all data to test speed: var spp = s.All<Passports>(); This one line was quick, however, then doing: sppp.Count() as well as a seperate test doing a foreach loop and incrementing a counter took a couple of minutes. This seems quite slow to me. Am I doing something wrong or am I expecting too much?

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• movie silent until button press, flash as3

  - by pixelGreaser

  I thought I could change the Boolean true/false value, but it's not working. How do I get this to hush, until the button is pressed? import flash.media.Sound; import flash.media.SoundChannel; var soundOn:Boolean = true; //music is ON when we start var myToons:TitleMusic = new TitleMusic(); var myChannel:SoundChannel = myToons.play(0,1000); // endless loop, in effect var myTransform:SoundTransform; mySoundButton.addEventListener(MouseEvent.CLICK,toggleSound); mySoundButton.buttonMode = true; mySoundButton.mouseChildren = false; function toggleSound(e:MouseEvent) { if(soundOn) { // turn sound off myTransform = new SoundTransform(); myTransform.volume = 0; // silent myChannel.soundTransform = myTransform; soundOn = false; mySoundButton.myButtonText.text = "click to turn sound ON"; } else // sound is off { // turn sound on myTransform = new SoundTransform(); myTransform.volume = 1; // full volume myChannel.soundTransform = myTransform; soundOn = true; mySoundButton.myButtonText.text = "click to turn sound OFF"; } }

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• XSLT inserting once off custom text

  - by BeraCim

  Hi all: The folloiwng is a pre-existing xml file. I was wondering how can I insert a element before the first element using xslt? <XmlFile> <!-- insert another <tag> element here --> <tag> <innerTag> </innerTag> </tag> <tag> <innerTag> </innerTag> </tag> <tag> <innerTag> </innerTag> </tag> </XmlFile> I was thinking of using a for-each loop and test the position = 0, but upon the first occurence of the for-each its already too late. This is a once-off text so I can't combine it with other xslt templates that are already inside the xsl file. Thanks.

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• SWT TabFolder: Weird Drawing Behaviour

  - by JesperGJensen

  Hello StackOverflow Experts Description I have an SWT Page with a TabFolder with a number of dynamically created TabItems. On each TabItem i crate a Composite and set the TabItem.setControl() to the Composite. I then use this Composite as the page on which i draw my items. I draw a set of Controls, including Textbox's and Labels. For the First, Default Tab, this works fine. No problems. Problem On tabs that is not the first tab i have the following problems: I am unable to visually alter then Edited/Enabled state of my Controls. I am unable to visually set the Text content of my elements My Controls look disabled and have a Greyed out look. But i am able to Select the content with my mouse and use CTRL+C to copy it out. So the text contet is there and they are Editable. Visually it is just not updated. Any comments are appeciated, Any requests for code, examples will be supplied and help Welcommed. Updates I tried added the suggest debug loop to the code, where i attempt to enable my Controls. This was the result: [main] INFO [dk.viking.controller.LayerController] - f038.stklok is now Editable [true] and enabled [true] [main] INFO [dk.viking.controller.LayerController] - true Text {} [main] INFO [dk.viking.controller.LayerController] - true Composite {} [main] INFO [dk.viking.controller.LayerController] - true TabFolder {} [main] INFO [dk.viking.controller.LayerController] - true Shell {Viking GUI}

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• Serial: write() throttling?

  - by damian

  Hi everyone, I'm working on a project sending serial data to control animation of LED lights, which need to stay in sync with a sound engine. There seems to be a large serial write buffer (OSX (POSIX) + FTDI chipset usb serial device), so without manually restricting the transmission rate, the animation system can get several seconds ahead of the serial transmission. Currently I'm manually restricting the serial write speed to the baudrate (8N1 = 10 bytes serial frame per 8 bytes data, 19200 bps serial - 1920 bytes per second max), but I am having a problem with the sound drifting out of sync over time - it starts fine, but after 10 minutes there's a noticeable (100ms+) lag between the sound and the lights. This is the code that's restricting the serial write speed (called once per animation frame, 'elapsed' is the duration of the current frame, 'baudrate' is the bps (19200)): void BufferedSerial::update( float elapsed ) { baud_timer += elapsed; if ( bytes_written > 1024 ) { // maintain baudrate float time_should_have_taken = (float(bytes_written)*10)/float(baudrate); float time_actually_took = baud_timer; // sleep if we have > 20ms lag between serial transmit and our write calls if ( time_should_have_taken-time_actually_took > 0.02f ) { float sleep_time = time_should_have_taken - time_actually_took; int sleep_time_us = sleep_time*1000.0f*1000.0f; //printf("BufferedSerial::update sleeping %i ms\n", sleep_time_us/1000 ); delayUs( sleep_time_us ); // subtract 128 bytes bytes_written -= 128; // subtract the time it should have taken to write 128 bytes baud_timer -= (float(128)*10)/float(baudrate); } } } Clearly there's something wrong, somewhere. A much better approach would be to be able to determine the number of bytes currently in the transmit queue, and try and keep that below a fixed threshold. Any advice appreciated.

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• Problem Loading multiple textures using multiple shaders with GLSL

  - by paj777

  I am trying to use multiple textures in the same scene but no matter what I try the same texture is loaded for each object. So this what I am doing at the moment, I initialise each shader: rightWall.SendShaders("wall.vert","wall.frag","brick3.bmp", "wallTex", 0); demoFloor.SendShaders("floor.vert","floor.frag","dirt1.bmp", "floorTex", 1); The code in SendShaders is: GLuint vert,frag; glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); char *vs = NULL,*fs = NULL; vert = glCreateShader(GL_VERTEX_SHADER); frag = glCreateShader(GL_FRAGMENT_SHADER); vs = textFileRead(vertFile); fs = textFileRead(fragFile); const char * ff = fs; const char * vv = vs; glShaderSource(vert, 1, &vv, NULL); glShaderSource(frag, 1, &ff, NULL); free(vs); free(fs); glCompileShader(vert); glCompileShader(frag); program = glCreateProgram(); glAttachShader(program, frag); glAttachShader(program, vert); glLinkProgram(program); glUseProgram(program); LoadGLTexture(textureImage, texture); GLint location = glGetUniformLocation(program, textureName); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture); glUniform1i(location, 0); And then in the main loop: rightWall.UseShader(); rightWall.Draw(); demoFloor.UseShader(); demoFloor.Draw(); Which ever shader is initialised last is the texture which is used for both objects. Thank you for your time and I appreciate any comments.

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• Select * from 'many to many' SQL relationship

  - by Rampant Creative Group

  I'm still learning SQL and my brain is having a hard time with this one. Say I have 3 tables: teams players and teams_players as my link table All I want to do is run a query to get each team and the players on them. I tried this: SELECT * FROM teams INNER JOIN teams_players ON teams.id = teams_players.team_id INNER JOIN players ON teams_players.player_id = players.id But it returned a separate row for each player on each team. Is JOIN the right way to do it or should I be doing something else? ----------------------------------------- Edit Ok, so from what I'm hearing, this isn't necessarily a bad way to do it. I'll just have to group the data by team while I'm doing my loop. I have not yet tried the modified SQL statements provided, but I will today and get back to you. To answer the question about structure - I guess I wasn't thinking about the returned row structure which is part of what lead to my confusion. In this particular case, each team is limited to 4 players (or less) so I guess the structure that would be helpful to me is something like the following: teams.id, teams.name, players.id, players.name, players.id, players.name, players.id, players.name, players.id, players.name, 1 Team ABC 1 Jim 2 Bob 3 Ned 4 Roy 2 Team XYZ 2 Bob 3 Ned 5 Ralph 6 Tom

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• twython search api rate limit: Header information will not be updated

  - by user2715478

  I want to handle the Search-API rate limit of 180 requests / 15 minutes. The first solution I came up with was to check the remaining requests in the header and wait 900 seconds. See the following snippet: results = search_interface.cursor(search_interface.search, q=k, lang=lang, result_type=result_mode) while True: try: tweet = next(results) if limit_reached(search_interface): sleep(900) self.writer(tweet) def limit_reached(search_interface): remaining_rate = int(search_interface.get_lastfunction_header('X-Rate-Limit-Remaining')) return remaining_rate <= 2 But it seems, that the header information are not reseted to 180 after it reached the two remaining requests. The second solution I came up with was to handle the twython exception for rate limitation and wait the remaining amount of time: results = search_interface.cursor(search_interface.search, q=k, lang=lang, result_type=result_mode) while True: try: tweet = next(results) self.writer(tweet) except TwythonError as inst: logger.error(inst.msg) wait_for_reset(search_interface) continue except StopIteration: break def wait_for_reset(search_interface): reset_timestamp = int(search_interface.get_lastfunction_header('X-Rate-Limit-Reset')) now_timestamp = datetime.now().timestamp() seconds_offset = 10 t = reset_timestamp - now_timestamp + seconds_offset logger.info('Waiting {0} seconds for Twitter rate limit reset.'.format(t)) sleep(t) But with this solution I receive this message INFO: Resetting dropped connection: api.twitter.com" and the loop will not continue with the last element of the generator. Have somebody faced the same problems? Regards.

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• Is there a tool that can refactor this C code correctly?

  - by Alex

  Lets say I have the following code (the array* function are what we use for resizable arrays and they operate on pointers-to-arrays that are null initialized): typedef struct MyStruct { int i; } MyStruct; MyStruct* GetNewMyStruct(int i) { MyStruct* s = malloc(sizeof(MyStruct)); s->i = i; return s; } int SomeFunction(int number, MyStruct *elem) { MyStruct **structs = NULL; int i; for (i = 0; i < number; i++) arrayPush(&structs, GetNewMyStruct(i)); arrayPush(&structs, elem); return arraySize(&structs); } I decide that SomeFunction is too large and I want refactor it. Currently where I work we use VisualAssist X, which has some refactoring capabilities, but when I use it on this it does not work correctly. If I attempt to use it to refactor out the loop, this is what I get: void MyMethod( int number, MyStruct ** structs ) { int i; for (i = 0; i < number; i++) arrayPush(&structs, GetNewMyStruct(i)); } int SomeFunction(int number, MyStruct *elem) { MyStruct **structs = NULL; MyMethod(number, structs); arrrayPush(&structs, elem); return arraySize(&structs); } This is not correct. MyMethod should take a MyStruct ***, not a MyStruct **. This is because the code I'm refactoring takes the address of structs. The result is that the refactored version will always return 1 (since only one object has been pushed into my array) rather than number+1. Are there other tools out there that do this type of refactoring correctly?

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• Overloading operator>> to a char buffer in C++ - can I tell the stream length?

  - by exscape

  I'm on a custom C++ crash course. I've known the basics for many years, but I'm currently trying to refresh my memory and learn more. To that end, as my second task (after writing a stack class based on linked lists), I'm writing my own string class. It's gone pretty smoothly until now; I want to overload operator that I can do stuff like cin my_string;. The problem is that I don't know how to read the istream properly (or perhaps the problem is that I don't know streams...). I tried a while (!stream.eof()) loop that .read()s 128 bytes at a time, but as one might expect, it stops only on EOF. I want it to read to a newline, like you get with cin to a std::string. My string class has an alloc(size_t new_size) function that (re)allocates memory, and an append(const char *) function that does that part, but I obviously need to know the amount of memory to allocate before I can write to the buffer. Any advice on how to implement this? I tried getting the istream length with seekg() and tellg(), to no avail (it returns -1), and as I said looping until EOF (doesn't stop reading at a newline) reading one chunk at a time.

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