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• Debugging unexpected error message - possible memory management problem?

  - by Ben Packard

  I am trying to debug an application that is throwing up strange (to my untutored eyed) errors. When I try to simply log the count of an array... NSLog(@"Array has %i items", [[self startingPlayers] count]); ...I sometimes get an error: -[NSCFString count]: unrecognized selector sent to instance 0x1002af600 or other times -[NSConcreteNotification count]: unrecognized selector sent to instance 0x1002af600 I am not sending 'count' to any NSString or NSNotification, and this line of code works fine normally. A Theory... Although the error varies, the crash happens at predictable times, immediately after I have run through some other code where I'm thinking I might have a memory management issue. Is it possible that the object reference is still pointing to something that is meant to be destroyed? Sorry if my terms are off, but perhaps it's expecting the array at the address it calls 'count' on, but finds another previous object that shouldn't still be there (eg an NSString)? Would this cause the problem? If so, what is the most efficient way to debug and find out what is that address? Most of my debugging up until now involves inserting NSLogs, so this would be a good opportunity to learn how to use the debugger.

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• Reconstructing trees from a "fingerprint"

  - by awshepard

  I've done my SO and Google research, and haven't found anyone who has tackled this before, or at least, anyone who has written about it. My question is, given a "universal" tree of arbitrary height, with each node able to have an arbitrary number of branches, is there a way to uniquely (and efficiently) "fingerprint" arbitrary sub-trees starting from the "universal" tree's root, such that given the universal tree and a tree's fingerprint, I can reconstruct the original tree? For instance, I have a "universal" tree (forgive my poor illustrations), representing my universe of possibilities: Root / / / | \ \ ... \ O O O O O O O (Level 1) /|\/|\...................\ (Level 2) etc. I also have tree A, a rooted subtree of my universe Root / /|\ \ O O O O O / Etc. Is there a way to "fingerprint" the tree, so that given that fingerprint, and the universal tree, I could reconstruct A? I'm thinking something along the lines of a hash, a compression, or perhaps a functional/declarative construction? Big-O analysis (in time or space) is a plus. As a for-instance, a nested expression like: {{(Root)},{(1),(2),(3)},{(2,3),(1),(4,5)}...} representing the actual nodes present at each level in the tree is probably valid, but can it be done more efficiently?

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• How to suppress error message details to general DNN Users

  - by thames

  I have a DNN site (05.02.03) in test and nearing release into production and I would like to suppress the details of error messages (i.e. Null Reference Exception, and others) to general users (admins can still see the details). Debug is off in the web.config. By suppressing, I mean the only error message I want to display to the general user (all users) is something like "An Exception has occured". I don't want the details of that exception to be displayed to the general user. I still want it logged in greater detail in the Event Viewer. How would I go about doing this? Update: I have "Use Custom Error Messages" checked. Which shows a error message like: A critical error has occurred.[vbCrLf] Object reference not set to an instance of an object. I want just the "A critical error has occured." error message to be displayed to general users. I don't want the "Object referece not set to an instance of an object." to be displayed to general users

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• Nginx Rate Limiting by Referrer?

  - by SteveEdson

  I've successfully set up rate limiting on IP addresses like so, limit_req_zone $binary_remote_addr zone=one:10m rate=1r/s; But I was wondering if its possible to do the same on referrers? For example, if a site gets placed in an iframe on a third party site, which generates too much traffic to handle. I can't find any nginx variables for the referrer anywhere. Is this possible? Or can the solution be achieved in a different way? Thanks.

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• Copy constructor using private attributes

  - by Pedro Magueija

  Hello all, My first question here so be gentle. I would like arguments for the following code: public class Example { private String name; private int age; ... // copy constructor here public Example(Example e) { this.name = e.name; // accessing a private attribute of an instance this.age = e.age; } ... } I believe this breaks the modularity of the instance passed to the copy construct. This is what I believe to be correct: public class Example { private String name; private int age; ... // copy constructor here public Example(Example e) { this.setName(e.getName()); this.setAge(e.getAge()); } ... } A friend has exposed a valid point of view, saying that in the copy construct we should create the object as fast as possible. And adding getter/setter methods would result in unnecessary overhead. I stand on a crossroad. Can you shed some light?

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• Can't connect to SQL Server 2005 Express from an ASP.NET C# page

  - by Aviv

  Hey guys, I have an MS SQL Server 2005 Express running on a VPS. I'm using pymssql in Python to connect to my server with the following code: conn = pymssql.connect(host='host:port', user='me', password='pwd', database='db') and it works perfectly. When I try to connect to the server from an ASP.NET C# page with the following code: SqlConnection myConnection = new SqlConnection("Data Source=host,port;Network Library=DBMSSOCN; Initial Catalog=db;User ID=me;Password=pwd;"); myConnection.Open(); When I run the ASP.NET page I get the following exception at myConnection.Open();: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) I tried restarting the SQL Server but I had no luck. Can anyone point me out to what I'm missing here? Thanks!

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• COM-Objects containing maps / content error(0)

  - by Florian Berzsenyi

  I'm writing a small wrapper to get familiar with some important topics in C++ (WinAPI, COM, STL,OOP). For now, my class shall be able to create a (child) window. Mainly, this window is connected to a global message loop that distribute messages to a local loop of the right instance (global is static, local is virtual). Obviously, there are surely better ways to do that but I'm using std::maps to store HWND and their instance pointer in pairs (the Global loop looks for the pointer with the HWND-parameter, gets itself the pointer from the map and calls then the local loop). Now, it appears that the map does not accept any values because of a unknown reason. It seems to allocate enough space but something went wrong anyway [ (error) 0 is displayed instead of the entries in visual C++). I've looked that up in google as well and found out that maps cause some trouble when used in classes AND DLLs. May this be the reason and is there any solution?? Protected scope of class: static std::map<HWND,MAP_BASE_OBJECT*> m_LoopBuf Implementation in .cpp-file: std::map<HWND,MAP_BASE_OBJECT*> HWindow::m_LoopBuf;

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• Tmux causes Emacs glitch

  - by killy9999

  Recently I started using Tmux, but I noticed that it causes a strange Emacs glitch. When I open source code for elisp or haskell, the comments aren't highlighted. Only the comment sign is (; in case of elisp, -- in case of haskell). The rest of the commented line is in normal colour. When I run Emacs outside of Tmux everything works as expected - the whole commented line is highlighted in a colour denoting a comment. Any ideas why this is happening? SOLUTION: Based on Stefan's comment I added this to my .emacs file: (custom-set-variables (custom-set-faces '(font-lock-comment-face ((((class color) (min-colors 8) (background dark)) (:foreground "red")))))) Now the comments are displayed in red, just like comment delimiters.

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• Launch command on remote Windows machine, given admin credentials

  - by Bilal Aslam

  I have a Windows Server 2008 instance on Amazon EC2 (Amazon's cloud compute platform, which provides VMs in the cloud). It has an external IP, and I have an admin account on the box. I would like to 'bootstrap' this instance remotely i.e. I want to run commands to download, install and configure apps on it, all without having to log on even once. I have figured out how to do this to a remote, domain-joined computer using WMI. I can even use psexec to get what I want, as long as the remote computer is part of the domain. However, I have NOT been able to do for a remote computer on EC2. Here are some specific restrictions: 1) The remote computer is not part of my domain, hence no Kerberos 2) The remote computer does not have a cert I trust, or vice versa I am sure I am running into to some auth/trust restriction. Is there any way I can run a single command on the remote, given that I have admin privileges? I'm not tied down to using WMI, but I do need to run a command somehow. Feels like this should be a solved problem.

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• Sorting downloads folder with bash script

  - by Marek

  I'm writing script for my own needs to sort Downloads folder on my mac in bash. I pass to the function parameters: source directory, destination directory and array of file extensions I want to move. My problem is that when function is in "find" line then it copies just one file with that extension but when I remove all variables and I put parameters directly then it works fine. What's going on ? function moveFaster(){ clear src=$1 dst=$2 typ=$3 if [ ! -d $dst ] then mkdir $dst fi for i in "${typ[@]}" do find $src -name "${i}" -exec mv {} ${dst} \; done }

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• How can I fix this configure error?

  - by balor123

  I'm trying to build mosh from source on a SUSE10 machine and am getting the following error: checking for protobuf... no configure: error: Package requirements (protobuf) were not met: No package 'protobuf' found Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively, you may set the environment variables protobuf_CFLAGS and protobuf_LIBS to avoid the need to call pkg-config. See the pkg-config man page for more details. I downloaded the source to protobuf and installed it in a custom path as well. I'm not using a package manager for any of this and cannot for various reasons outside the scope of the question. I added that custom path to my PATH and rehashed. Typically, this is enough for configure but in this case its not doing the trick. I added the prefix for protobuf to PKG_CONFIG_PATH but am still hitting this error. What should I do next to get past this error?

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• PDF to PNG Processor - Paperclip

  - by Josh Crowder

  I am trying to develop a system in which a user can upload a slideshow (pdf) and it'll export each slide as a png. After some digging around I came across a post on here that suggested using a processor. I've had a go, but I cant get the command to run, if it is running then I don't know what is happening because no errors are being shown. Any help would be appreciated! module Paperclip class Slides < Processor def initialize(file, options = {}, attachment = nill) super @file = file @instance = options[:instance] @current_format = File.extname(@file.path) @basename = File.basename(@file.path, @current_format) end def make dst = Tempfile.new( [ @basename, @format].compact.join(".")) dst.binmode command = <<-end_command -size 640x300 #{ File.expand_path(dst.path) } tester.png end_command begin success = Paperclip.run("convert", command.gsub(/\s+/, " "))) rescue PaperclipCommandLineError raise PaperclipError, "There was an error processing the thumbnail for #{@basename}" end end end end I think my problem is with the convert command... When I run that command by hand, it works but it doesn't give the details of each slide it just executes it. What I need to happen is once its made all the slides, pass back the data to a new model... or I know where all the slides are, but once I get to that point I'm not sure what todo.

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• Calculate new position of player

  - by user1439111

  Edit: I will summerize my question since it is very long (Thanks Len for pointing it out) What I'm trying to find out is to get a new position of a player after an X amount of time. The following variables are known: - Speed - Length between the 2 points - Source position (X, Y) - Destination position (X, Y) How can I calculate a position between the source and destion with these variables given? For example: source: 0, 0 destination: 10, 0 speed: 1 so after 1 second the players position would be 1, 0 The code below works but it's quite long so I'm looking for something shorter/more logical ====================================================================== I'm having a hard time figuring out how to calculate a new position of a player ingame. This code is server sided used to track a player(It's a emulator so I don't have access to the clients code). The collision detection of the server works fine I'm using bresenham's line algorithm and a raycast to determine at which point a collision happens. Once I deteremined the collision I calculate the length of the path the player is about to walk and also the total time. I would like to know the new position of a player each second. This is the code I'm currently using. It's in C++ but I am porting the server to C# and I haven't written the code in C# yet. // Difference between the source X - destination X //and source y - destionation Y float xDiff, yDiff; xDiff = xDes - xSrc; yDiff = yDes - ySrc; float walkingLength = 0.00F; float NewX = xDiff * xDiff; float NewY = yDiff * yDiff; walkingLength = NewX + NewY; walkingLength = sqrt(walkingLength); const float PI = 3.14159265F; float Angle = 0.00F; if(xDes >= xSrc && yDes >= ySrc) { Angle = atanf((yDiff / xDiff)); Angle = Angle * 180 / PI; } else if(xDes < xSrc && yDes >= ySrc) { Angle = atanf((-xDiff / yDiff)); Angle = Angle * 180 / PI; Angle += 90.00F; } else if(xDes < xSrc && yDes < ySrc) { Angle = atanf((yDiff / xDiff)); Angle = Angle * 180 / PI; Angle += 180.00F; } else if(xDes >= xSrc && yDes < ySrc) { Angle = atanf((xDiff / -yDiff)); Angle = Angle * 180 / PI; Angle += 270.00F; } float WalkingTime = (float)walkingLength / (float)speed; bool Done = false; float i = 0; while(i < walkingLength) { if(Done == true) { break; } if(WalkingTime >= 1000) { Sleep(1000); i += speed; WalkTime -= 1000; } else { Sleep(WalkTime); i += speed * WalkTime; WalkTime -= 1000; Done = true; } if(Angle >= 0 && Angle < 90) { float xNew = cosf(Angle * PI / 180) * i; float yNew = sinf(Angle * PI / 180) * i; float NewCharacterX = xSrc + xNew; float NewCharacterY = ySrc + yNew; } I have cut the last part of the loop since it's just 3 other else if statements with 3 other angle conditions and the only change is the sin and cos. The given speed parameter is the speed/second. The code above works but as you can see it's quite long so I'm looking for a new way to calculate this. btw, don't mind the while loop to calculate each new position I'm going to use a timer in C# Thank you very much

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• Status code in nginx try_files directive

  - by Hamish

  Is it possible to use the current status code as a parameter in try_files? For example, we try to provide a host specific 503 static response, or a server-wide fallback if it wasn't found: error_page 503 @error503; location @error503 { root /path_to_static_root/; try_files /$host/503.html /503.html =503; } There are a number of these directives, so it would be convenient to do something like: error_page 404 @error error_page 500 @error error_page 503 @error location @error { root /path_to_static_root/; try_files /$host/$status.html /$status.html =$status; } But the Variables documentation doesn't list anything that we could use to do this. Is it possible, or is there an alternative way to do this?

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• How can I use `SetEnvIf` to clear an Apache2 environment variable?

  - by Jamie

  In my apache2 configuration I've got these lines: SetEnv log_everything # Create the environment variables based on access requests SetEnvIf Request_URI "^/orders/.*$" download_access !log_everything SetEnvIf Request_URI "^/download/.*$" download_access !log_everything SetEnvIf Request_URI "^/wg/.*$" wg_1x1_access !log_everything # Log the accesses using the generated environment variable as conditionals. CustomLog ${APACHE_LOG_DIR}/download.log combined env=download_access CustomLog ${APACHE_LOG_DIR}/wg.log combined env=wg_1x1_access RewriteEngine on RewriteRule "^/wg/.+$" "/wg/1x1.gif" ErrorLog ${APACHE_LOG_DIR}/error.log CustomLog ${APACHE_LOG_DIR}/access.log combined env=log_everything Which currently logs all the "download" and "orders" requests to "download.log" and "wg" requests to "wg.log", but everything is also going to access.log. How can I configure this so that "wg" and "download/orders" requests won't be duplicated in access.log?

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• Javascript force GC collection? / Forcefully free object?

  - by plash

  I have a js function for playing any given sound using the Audio interface (creating a new instance for every call). This works quite well, until about the 32nd call (sometimes less). This issue is directly related to the release of the Audio instance. I know this because I've allowed time for the GC in Chromium to run and it will allow me to play another 32 or so sounds again. Here's an example of what I'm doing: <html><head> <script language="javascript"> function playSound(url) { snd = new Audio(url); snd.play(); delete snd; snd = null; } </script> </head> <body> <a href="#" onclick="playSound('blah.mp3');">Play sound</a> </body></html> I also have this, which works well for pages that have less than 32 playSound calls: var AudioPlayer = { cache: {}, play: function(url) { if (!AudioPlayer.cache[url]) AudioPlayer.cache[url] = new Audio(url); AudioPlayer.cache[url].play(); } }; But this will not work for what I want to do (dynamically replace a div with other content (from separate files), which have even more sounds on them - 1. memory usage would easily skyrocket, 2. many sounds will never play). I need a way to release the sound immediately. Is it possible to do this? I have found no free/close/unload method for the Audio interface. The pages will be viewed locally, so the constant loading of sounds is not a big factor at all (and most sounds are rather short).

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• XmlSerialize a custom collection with an Attribute

  - by roomaroo

  I've got a simple class that inherits from Collection and adds a couple of properties. I need to serialize this class to XML, but the XMLSerializer ignores my additional properties. I assume this is because of the special treatment that XMLSerializer gives ICollection and IEnumerable objects. What's the best way around this? Here's some sample code: using System.Collections.ObjectModel; using System.IO; using System.Xml.Serialization; namespace SerialiseCollection { class Program { static void Main(string[] args) { var c = new MyCollection(); c.Add("Hello"); c.Add("Goodbye"); var serializer = new XmlSerializer(typeof(MyCollection)); using (var writer = new StreamWriter("test.xml")) serializer.Serialize(writer, c); } } [XmlRoot("MyCollection")] public class MyCollection : Collection<string> { [XmlAttribute()] public string MyAttribute { get; set; } public MyCollection() { this.MyAttribute = "SerializeThis"; } } } This outputs the following XML (note MyAttribute is missing in the MyCollection element): <?xml version="1.0" encoding="utf-8"?> <MyCollection xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <string>Hello</string> <string>Goodbye</string> </MyCollection> What I want is <MyCollection MyAttribute="SerializeThis" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <string>Hello</string> <string>Goodbye</string> </MyCollection> Any ideas? The simpler the better. Thanks.

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• Java - SwingWorker - problem

  - by Yatendra Goel

  I am developing a Java Desktop Application. This app executes the same task public class MyTask implements Callable<MyObject> { in multiple thread simultaneously. Now, when a user clicks on a "start" button, I have created a SwingWorker myWorker and have executed it. Now, this myWorker creates multiple instances of MyTask and submits them to an ExecutorService. Each MyTask instance has a loop and generates an intermediate result at every iteration. Now, I want to collect these intermediate results from each MyTask instances as soon as they are generated. Then after collecting these intermediate results from every MyTask instance, I want to publish it through SwingWorker.publish(MyObject) so that the progress is shown on the EDT. Q1. How can I implement this? Should I make MyTask subclass of SwingWorker instead of Callable to get intermediate results also, because I think that Callable only returns final result. Q2. If the answer of Q1. is yes, then can you give me a small example to show how can I get those intermediate results and aggregate them and then publish them from main SwingWorker? Q3. If I can't use SwingWorker in this situation, then how can I implement this?

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• WPF : Access Application Resources when not referencing Shell from App.xaml

  - by CF_Maintainer

  I am beginner in WPF. My App.xaml looks like below app.xaml <Application x:Class="ContactManager.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <Application.Resources> <Color x:Key="lightBlueColor">#FF145E9D</Color> <SolidColorBrush x:Key="lightBlueBrush" Color="{StaticResource lightBlueColor}" /> </Application.Resources> I do not set the startupuri since I want to a presenter first approach. I do the following in app.xaml.cs protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e); var appPresenter = new ApplicationPresenter( new Shell(), new ContactRepository()); appPresenter.LaunchView(); } I have a usercontrol called "SearchBar.xaml" which references "lightBlueBrush" as a staticResource. When I try to open "Shell.xaml" in the designer it tells me : The "shell.xaml" cannot be loaded at design time because it says it could not create an instance of type "SearchBar.xaml". When I debugged the devenv.exe using another visual studio instance it tells me that it does not have access to the Brush I created in app.resources. If one is doing a Presenter first approach, how does one access resources? I had this working when the startupURI was "Shell.xaml" and the startup event was not present. Any clues/ideas/suggestions. I am just trying to understand. Everything works as expected when I run the application just not @ design time.

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• ASP.NET "Object reference not set..." error

  - by Roman

  Hi, I have a website written using ASP.NET. We have a development machine and a deployment server. The site works great on the development machine, but when is transfered (using simple FTP Upload) generates strange behavior. It starts working just fine, but after a while stops working and throws an exception "Exception: Object reference not set to an instance of an object.". The deal is that the absolute path of the website on the development machine is different than on the deployment server (and why should they be similar?) and the exact error is: Exception: Object reference not set to an instance of an object. at SOMEPROJECT_Objects.Player..ctor(Int32 PlayerID) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT_Objects\Player.cs:line 123 at SOMEPROJECT_GameLayer.M_Game.PlayerActiveGame(Int32 PlayerID) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT_GameLayer\M_Game.cs:line 85 at Web.getsms.Page_Load(Object sender, EventArgs e) in C:\inetpub\wwwroot\SOMEPROJECTSolution\ALLPROJECT\SOMEPROJECT-sms\Web\getsms.aspx.cs:line 59 The address that it is looking for is the address on the DEVELOPMENT machine, where as the site now resides on the deployment server. Any ideas why this happens would be appreciated. Thanks, Roman

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• Assembly unavailable after Web.config change

  - by tags2k

  I'm using a custom framework that uses reflection to do a GetTypeByName(string fullName) on the fully-qualified type name that it gets from the database, to create an instance of said type and add it to the page, resulting in a standard modular kind of thing. GetTypeByName is a utility function of mine that simply iterates through Thread.GetDomain().GetAssemblies(), then performs an assembly.GetType(fullName) to find the relevant type. Obviously this result gets cached for future reference and speed. However, I'm experiencing some issues whereby if the web.config gets updated (and, in some scarier instances if the application pool gets recycled) then it will lose all knowledge of certain assemblies, resulting in the inability to render an instance of the module type. Debugging shows that the missing assembly literally does not exist in the current thread assemblies list. To get around this I added a second check which is a bit dirty but recurses through the /bin/ directory's DLLs and checks that each one exists in the assemblies list. If it doesn't, it loads it using Assembly.Load and fixing the context issue thanks to 'Solving the Assembly Load Context Problem'. This would work, only it seems that (and I'm aware this shouldn't be possible) some projects still have access to the missing assembly, for example my actual web project rather than the framework itself - and it then complains that duplicate references have been added! Has anyone ever heard of anything like this, or have any ideas why an assembly would simply drop out of existence on a config change? Short of a solution, what is the most elegant workaround to get all the assemblies in the bin to reload? It needs to be all in one "hit" so that the site visitors don't see any difference other than a small delay, so an app_offline.htm file is out of the question. Programatically renaming a DLL in the bin and then naming it back does work, but requires "modify" permissions for the IIS user account, which is insane. Thanks for any pointers the community can gather!

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• System information shown when booting Debian

  - by WebDevHobo

  When booting Debian, you'll see it printing a lot of information about the system variables and such. I don't really need to see all that, so I'd like to modify some scripts to make sure that on boot, it just does what it has to do, without printing it on the screen. Just something I fancy. Offcourse, still seeing errors would be nice. But that long slur of text, I could do without. I've tried looking it up, but I can't find documentation on this specific thing anywhere.

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• Does pressing Back always cause Activity to finish()?

  - by stormin986

  I've heard that pressing the back button will essentially cause the current Activity to finish(). Is this always the case? Seems like it would be with the way it pops the Activity off the stack. The one situation I'm not so sure about is when the root Activity in a Task has back pressed. I'm currently experiencing a very weird effect, described as follows: On loading my application, the first Activity is for initialization, and once it finishes, it calls my main Activity (a TabActivity). This first init activity has android:noHistory="true" set in the Manifest so pressing Back from my main Activity won't go back to that. It goes to the Launcher. When I click on my App in the Launcher a second time, the initialization activity loads again, and loads the main Activity when done. Almost immediately after, it loads a second instance of my main Activity. But ONLY after the Application has already been run once, and was exited by pressing BACK from the main Activity. It does it every subsequent time until I force quit the app or load a new version from the IDE. Based on this, I am suspecting some kind of Activity instance is lying around and being reused, since it only happens on the second+ time I run the application (and exit with BACK -- using HOME just returns to the last state of the app, no big deal). Anyone have any thoughts??

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• Is it normal for C++ static initialization to appear twice in the same backtrace?

  - by Joseph Garvin

  I'm trying to debug a C++ program compiled with GCC that freezes at startup. GCC mutex protects function's static local variables, and it appears that waiting to acquire such a lock is why it freezes. How this happens is rather confusing. First module A's static initialization occurs (there are __static_init functions GCC invokes that are visible in the backtrace), which calls a function Foo(), that has a static local variable. The static local variable is an object who's constructor calls through several layers of functions, then suddenly the backtrace has a few ??'s, and then it's is in the static initialization of a second module B (the __static functions occur all over again), which then calls Foo(), but since Foo() never returned the first time the mutex on the local static variable is still set, and it locks. How can one static init trigger another? My first theory was shared libraries -- that module A would be calling some function in module B that would cause module B to load, thus triggering B's static init, but that doesn't appear to be the case. Module A doesn't use module B at all. So I have a second (and horrifying) guess. Say that: Module A uses some templated function or a function in a templated class, e.g. foo<int>::bar() Module B also uses foo<int>::bar() Module A doesn't depend on module B at all At link time, the linker has two instances of foo<int>::bar(), but this is OK because template functions are marked as weak symbols... At runtime, module A calls foo<int>::bar, and the static init of module B is triggered, even though module B doesn't depend on module A! Why? Because the linker decided to go with module B's instance of foo::bar instead of module A's instance at link time. Is this particular scenario valid? Or should one module's static init never trigger static init in another module?

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• Mix Audio tracks with offset in SOX

  - by Laramie

  From ASP.Net, I am using FFMPEG to convert flv files on a Flash Media Server to wavs that I need to mix into a single MP3 file. I originally attempted this entirely with FFMPEG but eventually gave up on the mixing step because I don't believe it it possible to combine audio only tracks into a single result file. I would love to be wrong. I am now using FFMPEG to access the FLV files and extract the audio track to wav so that SOX can mix them. The problem is that I must offset one of the audio tracks by a few seconds so that they are synchronized. Each file is one half of a conversation between a student and a teacher. For example teacher.wav might need to begin 3.3 seconds after student.wav. I can only figure out how to mix the files with SOX where both tracks begin at the same time. My best attempt at this point is: ffmpeg -y -i rtmp://server/appName/instance/student.flv -ac 1 student.wav ffmpeg -y -i rtmp://server/appName/instance/teacher.flv -ac 1 teacher.wav sox -m student.wav teacher.wav combined.mp3 splice 3.3 These tools (FFMEG/SoX) were chosen based on my best research, but are not required. Any working solution would allow an ASP.Net service to input the two FMS flvs and create a combined MP3 using open-source or free tools.

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