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  • Segmentation fault 11 in MacOS X- C++ [migrated]

    - by Marcos Cesar Vargas Magana
    all. I have a "segmentation fault 11" error when I run the following code. The code actually compiles but I get the error at run time. //** Terror.h ** #include <iostream> #include <string> #include <map> using std::map; using std::pair; using std::string; template<typename Tsize> class Terror { public: //Inserts a message in the map. static Tsize insertMessage(const string& message) { mErrorMessages.insert( pair<Tsize, string>(mErrorMessages.size()+1, message) ); return mErrorMessages.size(); } private: static map<Tsize, string> mErrorMessages; } template<typename Tsize> map<Tsize,string> Terror<Tsize>::mErrorMessages; //** error.h ** #include <iostream> #include "Terror.h" typedef unsigned short errorType; typedef Terror<errorType> error; errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); //** main.cpp ** #include <iostream> #include "error.h" using namespace std; int main() { try { throw error(memoryAllocationError); } catch(error& err) { } } I have kind of debugging the code and the error happens when the message is being inserted in the static map member. An observation is that if I put the line: errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); inside the "main()" function instead of at global scope, then everything works fine. But I would like to extend the error messages at global scope, not at local scope. The map is defined static so that all instances of "error" share the same error codes and messages. Do you know how can I get this or something similar. Thank you very much.

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  • Subterranean IL: Volatile

    - by Simon Cooper
    This time, we'll be having a look at the volatile. prefix instruction, and one of the differences between volatile in IL and C#. The volatile. prefix volatile is a tricky one, as there's varying levels of documentation on it. From what I can see, it has two effects: It prevents caching of the load or store value; rather than reading or writing to a cached version of the memory location (say, the processor register or cache), it forces the value to be loaded or stored at the 'actual' memory location, so it is then immediately visible to other threads. It forces a memory barrier at the prefixed instruction. This ensures instructions don't get re-ordered around the volatile instruction. This is slightly more complicated than it first seems, and only seems to matter on certain architectures. For more details, Joe Duffy has a blog post going into the details. For this post, I'll be concentrating on the first aspect of volatile. Caching field accesses To demonstrate this, I created a simple multithreaded IL program. It boils down to the following code: .class public Holder { .field public static class Holder holder .field public bool stop .method public static specialname void .cctor() { newobj instance void Holder::.ctor() stsfld class Holder Holder::holder ret }}.method private static void Main() { .entrypoint // Thread t = new Thread(new ThreadStart(DoWork)) // t.Start() // Thread.Sleep(2000) // Console.WriteLine("Stopping thread...") ldsfld class Holder Holder::holder ldc.i4.1 stfld bool Holder::stop call instance void [mscorlib]System.Threading.Thread::Join() ret}.method private static void DoWork() { ldsfld class Holder Holder::holder // while (!Holder.holder.stop) {} DoWork: dup ldfld bool Holder::stop brfalse DoWork pop ret} If you compile and run this code, you'll find that the call to Thread.Join() never returns - the DoWork spinlock is reading a cached version of Holder.stop, which is never being updated with the new value set by the Main method. Adding volatile to the ldfld fixes this: dupvolatile.ldfld bool Holder::stopbrfalse DoWork The volatile ldfld forces the field access to read direct from heap memory, which is then updated by the main thread, rather than using a cached copy. volatile in C# This highlights one of the differences between IL and C#. In IL, volatile only applies to the prefixed instruction, whereas in C#, volatile is specified on a field to indicate that all accesses to that field should be volatile (interestingly, there's no mention of the 'no caching' aspect of volatile in the C# spec; it only focuses on the memory barrier aspect). Furthermore, this information needs to be stored within the assembly somehow, as such a field might be accessed directly from outside the assembly, but there's no concept of a 'volatile field' in IL! How this information is stored with the field will be the subject of my next post.

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  • Creating collection with no code (almost)

    - by Sean Feldman
    When doing testing, I tend to create an object mother for the items generated multiple times for specifications. Quite often these objects need to be a part of a collection. A neat way to do so is to leverage .NET params mechanism: public static IEnumerable<T> CreateCollection<T>(params T[] items) { return items; } And usage is the following: private static IEnumerable<IPAddress> addresses = CreateCollection(new IPAddress(123456789), new IPAddress(987654321));

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  • Minimizing Dependencies For GUIs

    - by tuba09
    I've been working on a project, and have been charged with designing the projects GUI front-end. I'm coding in Java and using the Swing toolkit. Usability-wise, the GUI front-end follows all of Nielsen's heuristics. Users can easily get to where they want to go through the click of a button / JComboBox. Essentially, in Swing terms, what happens is their actions drive the creation/deletion of custom panels. The GUI is coming along fine for the most part. However, I have to admit to being utterly dismayed at the tight web of dependencies my code is being smothered in. The main problem that I've encountered, that I haven't been able to fix as of yet, is how to keep a reference to the panels/buttons being changed. I'll give an example: Say there's a button A Say there's a panel B displaying picture C Say there's another picture D (not currently being displayed by panel B) When user clicks A, panel B should remove picture C and display picture D My question is, what's the best way of keeping track of panel B? Since I need a global point of access to panel B, my solution has so far been to just shoehorn it into a static variable, and access it through a series of static getters and setters. And this static variable is usually stored in the reference's original class. I.e. UserPanel has a static variable that stores a reference to itself. Is there an easy, tried-and-true way of dealing with these kinds of situations? Like my GUI works fine, but it is not modular and/or robust at all. To add to this, the dreaded 'cyclical dependencies' issue that's shunned by so many programmers is out here in full effect. I'm fairly new to development and just want to make sure that my code will be fairly extensible and won't cause much of a headache to the next person that decides to get a try at it. I know there's loads of books out there that probably have a nice elegant solution to this, but unfortunately I just don't have the time to leisure read right now. I need something that's quick and dirty. Thanks in advance

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  • Parenting Opengl with Groups in LibGDX

    - by Rudy_TM
    I am trying to make an object child of a Group, but this object has a draw method that calls opengl to draw in the screen. Its class its this public class OpenGLSquare extends Actor { private static final ImmediateModeRenderer renderer = new ImmediateModeRenderer10(); private static Matrix4 matrix = null; private static Vector2 temp = new Vector2(); public static void setMatrix4(Matrix4 mat) { matrix = mat; } @Override public void draw(SpriteBatch batch, float arg1) { // TODO Auto-generated method stub renderer.begin(matrix, GL10.GL_TRIANGLES); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y0, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y0, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y0, 0f); renderer.end(); } } In my screen class I have this, i call it in the constructor MyGroupClass spriteLab = new MyGroupClass(spriteSheetLab); OpenGLSquare square = new OpenGLSquare(); square.setX0(100); square.setY0(200); square.setX1(400); square.setY1(280); square.color.set(Color.BLUE); square.setSize(); //spriteLab.addActorAt(0, clock); spriteLab.addActor(square); stage.addActor(spriteLab); And the render in the screen I have @Override public void render(float arg0) { this.gl.glClear(GL10.GL_COLOR_BUFFER_BIT |GL10.GL_DEPTH_BUFFER_BIT); stage.draw(); stage.act(Gdx.graphics.getDeltaTime()); } The problem its that when i use opengl with parent, it resets all the other chldren to position 0,0 and the opengl renderer paints the square in the exact position of the screen and not relative to the parent. I tried using batch.enableBlending() and batch.disableBlending() that fixes the position problem of the other children, but not the relative position of the opengl drawing and it also puts alpha to the glDrawing. What am i doing wrong?:/

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  • Problem Loading a DLL (4 replies)

    I'm having some issues now that I can't see what I'm doing wrong. I'm Pinvoking a non WindowsAPI DLL (I mean, not a dll provided on windows). Pinvoking LoadLibrary, I can get a IntPtr to any WindowsAPI DLL, but never I can get a pointer to my DLL. The code I'm using is very simple, like this one: [DllImport(&quot;kernel32.dll&quot;, SetLastError true)] public static extern IntPtr LoadLibrary(); static void ...

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  • Multi subnet in ubuntu with dnsmasq

    - by Fox Mulder
    I have a multi lan port box that install ubuntu server 11.10. I am setup network in /etc/network/interfaces file as follow: auto lo iface lo inet loopback auto eth0 iface eth0 inet static      address 192.168.128.254      netmask 255.255.255.0      network 192.168.128.0      broadcast 192.168.128.255      gateway 192.168.128.1      dns-nameservers xxxxxx auto eth1 iface eth1 inet static      address 192.168.11.1      netmask 255.255.255.0      network 192.168.11.0      broadcast 192.168.11.255 auto eth2 iface eth2 inet static      address 192.168.21.1      netmask 255.255.255.0      network 192.168.21.0      broadcast 192.168.21.255 auto eth3 iface eth3 inet static      address 192.168.31.1      netmask 255.255.255.0      network 192.168.31.0      broadcast 192.168.31.255 I am also enable the ip forward by echo 1 /proc/sys/net/ipv4/if_forward in rc.local. my dnsmasq config as follow except-interface=eth0 dhcp-range=interface:eth1,set:wifi,192.168.11.101,192.168.11.200,255.255.255.0 dhcp-range=interface:eth2,set:kids,192.168.21.101,192.168.21.200,255.255.255.0 dhcp-range=interface:eth3,set:game,192.168.31.101,192.168.31.200,255.255.255.0 the dhcp was working fine in eth1,eth2,eth3, any machine plug in the subnet can get correct subnet's ip. My problem was, each subnet machine can't ping each other. for example. 192.168.11.101 can't ping 192.168.21.101 but can ping 192.168.128.1 192.168.31.101 can't ping 192.168.21.101 but can ping 192.168.128.1 I am also try to using route add -net 192.168.11.0 netmask 255.255.255.0 gw 192.168.11.1 (and also 192.168.21.0/192.168.31.0) at this multi-lan-port machine. But still won't work. Does anyone can help ? Thanks.

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  • Helper methods StartOfMonth and StartOfNextMonth

    - by Michael Freidgeim
    There are couple methods recently added to My DateTimeHelper class     public static DateTime StartOfMonth(this DateTime dateValue)         {             return new DateTime(dateValue.Year,dateValue.Month,1,0,0,0);         }         public static DateTime StartOfNextMonth(this DateTime dateValue)         {             return StartOfMonth(dateValue).AddMonths(1);         }

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  • Where to buy a domain for my local server [closed]

    - by Pradyut Bhattacharya
    I have made a website and hosted in my local computer using a static ip Where can i buy a domain name such as www.something.com such that it can redirect to my static IP. So that if i m using a page like a http://localhost/index.jsp it can be accessed by http://www.something.com/index.jsp Does it matter if i run the server locally or should I buy a managed web hosting server from a big company if the traffic is low on my site?

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  • Extension methods on a null object instance – something you did not know

    - by nmarun
    Extension methods gave developers with a lot of bandwidth to do interesting (read ‘cool’) things. But there are a couple of things that we need to be aware of while using these extension methods. I have a StringUtil class that defines two extension methods: 1: public static class StringUtils 2: { 3: public static string Left( this string arg, int leftCharCount) 4: { 5: if (arg == null ) 6: { 7: throw new ArgumentNullException( "arg" ); 8: } 9: return arg.Substring(0, leftCharCount); 10...(read more)

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  • Entity Framework 5, separating business logic from model - Repository?

    - by bnice7
    I am working on my first public-facing web application and I’m using MVC 4 for the presentation layer and EF 5 for the DAL. The database structure is locked, and there are moderate differences between how the user inputs data and how the database itself gets populated. I have done a ton of reading on the repository pattern (which I have never used) but most of my research is pushing me away from using it since it supposedly creates an unnecessary level of abstraction for the latest versions of EF since repositories and unit-of-work are already built-in. My initial approach is to simply create a separate set of classes for my business objects in the BLL that can act as an intermediary between my Controllers and the DAL. Here’s an example class: public class MyBuilding { public int Id { get; private set; } public string Name { get; set; } public string Notes { get; set; } private readonly Entities _context = new Entities(); // Is this thread safe? private static readonly int UserId = WebSecurity.GetCurrentUser().UserId; public IEnumerable<MyBuilding> GetList() { IEnumerable<MyBuilding> buildingList = from p in _context.BuildingInfo where p.Building.UserProfile.UserId == UserId select new MyBuilding {Id = p.BuildingId, Name = p.BuildingName, Notes = p.Building.Notes}; return buildingList; } public void Create() { var b = new Building {UserId = UserId, Notes = this.Notes}; _context.Building.Add(b); _context.SaveChanges(); // Set the building ID this.Id = b.BuildingId; // Seed 1-to-1 tables with reference the new building _context.BuildingInfo.Add(new BuildingInfo {Building = b}); _context.GeneralInfo.Add(new GeneralInfo {Building = b}); _context.LocationInfo.Add(new LocationInfo {Building = b}); _context.SaveChanges(); } public static MyBuilding Find(int id) { using (var context = new Entities()) // Is this OK to do in a static method? { var b = context.Building.FirstOrDefault(p => p.BuildingId == id && p.UserId == UserId); if (b == null) throw new Exception("Error: Building not found or user does not have access."); return new MyBuilding {Id = b.BuildingId, Name = b.BuildingInfo.BuildingName, Notes = b.Notes}; } } } My primary concern: Is the way I am instantiating my DbContext as a private property thread-safe, and is it safe to have a static method that instantiates a separate DbContext? Or am I approaching this all wrong? I am not opposed to learning up on the repository pattern if I am taking the total wrong approach here.

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  • Checking timeouts made more readable

    - by Markus
    I have several situations where I need to control timeouts in a technical application. Either in a loop or as a simple check. Of course – handling this is really easy, but none of these is looking cute. To clarify, here is some C# (Pseudo) code: private DateTime girlWentIntoBathroom; girlWentIntoBathroom = DateTime.Now; do { // do something } while (girlWentIntoBathroom.AddSeconds(10) > DateTime.Now); or if (girlWentIntoBathroom.AddSeconds(10) > DateTime.Now) MessageBox.Show("Wait a little longer"); else MessageBox.Show("Knock louder"); Now I was inspired by something a saw in Ruby on StackOverflow: Now I’m wondering if this construct can be made more readable using extension methods. My goal is something that can be read like “If girlWentIntoBathroom is more than 10 seconds ago” 1st attempt if (girlWentIntoBathroom > (10).Seconds().Ago()) MessageBox.Show("Wait a little longer"); else MessageBox.Show("Knock louder"); So I wrote an extension for integer that converts the integer into a TimeSpan public static TimeSpan Seconds(this int amount) { return new TimeSpan(0, 0, amount); } After that, I wrote an extension for TimeSpan like this: public static DateTime Ago(this TimeSpan diff) { return DateTime.Now.Add(-diff); } This works fine so far, but has a great disadvantage. The logic is inverted! Since girlWentIntoBathroom is a timestamp in the past, the right side of the equation needs to count backwards: impossible. Just inverting the equation is no solution, because it will invert the read sentence as well. 2nd attempt So I tried something new: if (girlWentIntoBathroom.IsMoreThan(10).SecondsAgo()) MessageBox.Show("Knock louder"); else MessageBox.Show("Wait a little longer"); IsMoreThan() needs to transport the past timestamp as well as the span for the extension SecondsAgo(). It could be: public static DateWithIntegerSpan IsMoreThan(this DateTime baseTime, int span) { return new DateWithIntegerSpan() { Date = baseTime, Span = span }; } Where DateWithIntegerSpan is simply: public class DateWithIntegerSpan { public DateTime Date {get; set;} public int Span { get; set; } } And SecondsAgo() is public static bool SecondsAgo(this DateWithIntegerSpan dateAndSpan) { return dateAndSpan.Date.Add(new TimeSpan(0, 0, dateAndSpan.Span)) < DateTime.Now; } Using this approach, the English sentence matches the expected behavior. But the disadvantage is, that I need a helping class (DateWithIntegerSpan). Has anyone an idea to make checking timeouts look more cute and closer to a readable sentence? Am I a little too insane thinking about something minor like this?

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  • C# Drawing On Separate Thread [migrated]

    - by Zaid
    I have a "public static" class called "DrawTest" and inside is a method public static DrawRandomRectangle(Bitmap g) { } I want to call that method and draw bunches of stuff and then update the pictureBox that uses the image on a separate thread. To simplify, I'm not trying to make anything specific I'm just trying to learn how to draw and update an image inside of a picturebox on a separate thread.

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  • Using extension methods to decrease the surface area of a C# interface

    - by brian_ritchie
    An interface defines a contract to be implemented by one or more classes.  One of the keys to a well-designed interface is defining a very specific range of functionality. The profile of the interface should be limited to a single purpose & should have the minimum methods required to implement this functionality.  Keeping the interface tight will keep those implementing the interface from getting lazy & not implementing it properly.  I've seen too many overly broad interfaces that aren't fully implemented by developers.  Instead, they just throw a NotImplementedException for the method they didn't implement. One way to help with this issue, is by using extension methods to move overloaded method definitions outside of the interface. Consider the following example: .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public interface IFileTransfer 2: { 3: void SendFile(Stream stream, Uri destination); 4: } 5:   6: public static class IFileTransferExtension 7: { 8: public static void SendFile(this IFileTransfer transfer, 9: string Filename, Uri destination) 10: { 11: using (var fs = File.OpenRead(Filename)) 12: { 13: transfer.SendFile(fs, destination); 14: } 15: } 16: } 17:   18: public static class TestIFileTransfer 19: { 20: static void Main() 21: { 22: IFileTransfer transfer = new FTPFileTransfer("user", "pass"); 23: transfer.SendFile(filename, new Uri("ftp://ftp.test.com")); 24: } 25: } In this example, you may have a number of overloads that uses different mechanisms for specifying the source file. The great part is, you don't need to implement these methods on each of your derived classes.  This gives you a better interface and better code reuse.

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  • Problem Loading a DLL (4 replies)

    I'm having some issues now that I can't see what I'm doing wrong. I'm Pinvoking a non WindowsAPI DLL (I mean, not a dll provided on windows). Pinvoking LoadLibrary, I can get a IntPtr to any WindowsAPI DLL, but never I can get a pointer to my DLL. The code I'm using is very simple, like this one: [DllImport(&quot;kernel32.dll&quot;, SetLastError true)] public static extern IntPtr LoadLibrary(); static void ...

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  • Can't ping devices by IP address for devices allocated IPs by DHCP

    - by GiddyUpHorsey
    I have a home network with a Trendnet wireless router and a Windows Domain. The Domain Controller/DNS server is a Windows 2000 Server and is configured to forward queries to DNS servers provided by the ISP. The router provides DHCP and is configured with the Windows 2000 Server as the DNS server. The network has been set up for a couple of years and usually works fine. When I connect iPhones to the network over WiFi, the router can ping the iPhones through its browser based admin interface, but Windows machines that are part of the Windows Domain cannot. A laptop was connected to the network over WiFi that wasn't joined to the domain and it could see the iPhones. The router UI shows that the laptop has a reserved IP allocated via DHCP. All machines either have a static or DHCP allocated IP on the 192.168.0.* subnet. Router - 192.168.0.1 - Static - Wired Windows Domain Controller - 192.168.0.8 - Static - Virtual Windows 7 Workstation - 192.168.0.200 - DHCP Auto - Wired VMWare ESXi Host - 192.168.0.201 - Static? - Wired iPhone 1 - 192.168.0.202 - DHCP Auto - WiFi iPhone 2 - 192.168.0.203 - DHCP Auto - WiFi Windows Vista Laptop - 192.168.0.204 - DHCP Reserved - WiFi Using the Windows 7 machine (200), I try to ping each machine and the only DHCP machine that responds is itself. The other DHCP machines fail with Reply from 192.168.0.200: Destination host unreachable.. Using nslookup fails with *** domain.controller.name can't find 192.168.0.203: Non-existent domain. Using the Windows 2000 Domain Controller (8), I try to ping each machine and the only DHCP machine that responds is the Windows 7 machine (200). Pinging the other DHCP machines fails with Request timed out.. Using nslookup also fails with *** domain.controller.name can't find 192.168.0.203: Non-existent domain. Using the iPhone 2 (203), I try to ping (Network Ping Lite) the machines with static IP addresses and that works fine. When I try to ping the Windows 7 machine (200) it is unable to get a response. How do I configure the DNS server/Windows Domain/Router properly so that the Windows Domain machines can see the IPs allocated via DHCP?

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  • Will spreading your servers load not just consume more recourses

    - by Saif Bechan
    I am running a heavy real-time updating website. The amount of recourses needed per user are quite high, ill give you an example. Setup Every visit The application is php/mysql so on every visit static and dynamic content is loaded. Recourses: apache,php,mysql Every second (no more than a second will just be too long) The website needs to be updated real-time so every second there is an ajax call thats updates the website. Recourses: jQuery,apache,php,mysql Avarage spending for single user (spending one minute and visited 3 pages) Apache: +/- 63 requests / responsess serving static and dynamic content (img,css,js,html) php: +/- 63 requests / responses mysql: +/- 63 requests / responses jquery: +/- 60 requests / responses Optimization I want to optimize this process, but I think that maybe it would be just the same in the end. Before implementing and testing (which will take weeks) I wanted to have some second opinions from you guys. Every visit I want to start off with having nginx in the front and work as a proxy to deliver the static content. Recources: Dynamic: apache,php,mysql Static: nginx This will spread the load on apache a lot. Every Second For the script that loads every second I want to set up Node.js server side javascript with nginx in te front. I want to set it up that jquery makes a request ones a minute, and node.js streams the data to the client every second. Recources: jQuery,nginx,node.js,mysql Avarage spending for single user (spending one minute and visited 3 pages) Nginx: 4 requests / responsess serving mostly static conetent(img,css,js) Apache: 3 requests only the pages php: 3 requests only the pages node.js: 1 request / 60 responses jquery: 1 request / 60 responses mysql: 63 requests / responses Optimization As you can see in the optimisation the load from Apache and PHP are lifted and places on nginx and node.js. These are known for there light footprint and good performance. But I am having my doubts, because there are still 2 programs extra loaded in the memory and they consume cpu. So it it better to have less programs that do the job, or more. Before I am going to spend a lot of time setting this up I would like to know if it will be worth the while.

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  • nginx rewrite for /blah/(.*) /$1

    - by skrewler
    I'm migrating from mod_php to nginx. I got everything working except for this rewrite.. I'm just not familiar enough with nginx configuration to know the correct way to do this. I came up with this by looking at a sample on the nginx site. server { server_name test01.www.myhost.com; root /home/vhosts/my_home/blah; access_log /var/log/nginx/blah.access.log; error_log /var/log/nginx/blah.error.log; index index.php; location / { try_files $uri $uri/ @rewrites; } location @rewrites { rewrite ^ /index.php last; rewrite ^/ht/userGreeting.php /js/iFrame/index.php last; rewrite ^/ht/(.*)$ /$1 last; rewrite ^/userGreeting.php$ /js/iFrame/index.php last; rewrite ^/a$ /adminLogin.php last; rewrite ^/boom\/(.*)$ /boom/index.php?q=$1 last; rewrite ^favicon.ico$ favico_ry.ico last; } # This block will catch static file requests, such as images, css, js # The ?: prefix is a 'non-capturing' mark, meaning we do not require # the pattern to be captured into $1 which should help improve performance location ~* \.(?:ico|css|js|gif|jpe?g|png)$ { # Some basic cache-control for static files to be sent to the browser expires max; add_header Pragma public; add_header Cache-Control "public, must-revalidate, proxy-revalidate"; } include php.conf; } The issue I'm having is with this rewrite: rewrite ^ht\/(.*)$ /$1 last; 99% of requests that will hit this rewrite are static files. So I think maybe it's getting sent to the static files section and that's where things are being messed up? I tried adding this but it didn't work: location ~* ^ht\/.*\.(?:ico|css|js|gif|jpe?g|png)$ { # Some basic cache-control for static files to be sent to the browser expires max; add_header Pragma public; add_header Cache-Control "public, must-revalidate, proxy-revalidate"; } Any help would be appreciated. I know the best thing to do would be to just change the references of /ht/whatever.jpg to /whatever.jpg in the code.. but that's not an option for now.

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  • Tips for maximizing Nginx requests/sec?

    - by linkedlinked
    I'm building an analytics package, and project requirements state that I need to support 1 billion hits per day. Yep, "billion". In other words, no less than 12,000 hits per second sustained, and preferably some room to burst. I know I'll need multiple servers for this, but I'm trying to get maximum performance out of each node before "throwing more hardware at it". Right now, I have the hits-tracking portion completed, and well optimized. I pretty much just save the requests straight into Redis (for later processing with Hadoop). The application is Python/Django with a gunicorn for the gateway. My 2GB Ubuntu 10.04 Rackspace server (not a production machine) can serve about 1200 static files per second (benchmarked using Apache AB against a single static asset). To compare, if I swap out the static file link with my tracking link, I still get about 600 requests per second -- I think this means my tracker is well optimized, because it's only a factor of 2 slower than serving static assets. However, when I benchmark with millions of hits, I notice a few things -- No disk usage -- this is expected, because I've turned off all Nginx logs, and my custom code doesn't do anything but save the request details into Redis. Non-constant memory usage -- Presumably due to Redis' memory managing, my memory usage will gradually climb up and then drop back down, but it's never once been my bottleneck. System load hovers around 2-4, the system is still responsive during even my heaviest benchmarks, and I can still manually view http://mysite.com/tracking/pixel with little visible delay while my (other) server performs 600 requests per second. If I run a short test, say 50,000 hits (takes about 2m), I get a steady, reliable 600 requests per second. If I run a longer test (tried up to 3.5m so far), my r/s degrades to about 250. My questions -- a. Does it look like I'm maxing out this server yet? Is 1,200/s static files nginx performance comparable to what others have experienced? b. Are there common nginx tunings for such high-volume applications? I have worker threads set to 64, and gunicorn worker threads set to 8, but tweaking these values doesn't seem to help or harm me much. c. Are there any linux-level settings that could be limiting my incoming connections? d. What could cause my performance to degrade to 250r/s on long-running tests? Again, the memory is not maxing out during these tests, and HDD use is nil. Thanks in advance, all :)

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  • Prepping a conference

    - by Laurent Bugnion
    I have had the chance to talk at many conferences these past few years, and came up with a way to prepare them which works really well for me. Most importantly, it would make it quite easy to overcome an emergency (for example if my laptop would suddenly lose data). The whole code as well as the slides and other documents are in the cloud. I also use source control for my demos, so that I always have the latest and the greatest, but also a history of changes I made to my demos. Finally I have a system of code snippets which works great, and I often had very positive remarks from the audience regarding that. Putting everything in the cloud The one thing I used to be the most scared of was a sudden crash of my laptop, and being unable to restore in time for a conference. Most conferences ask speakers to send slides a few days (or weeks…) in advance, but let's face it, we all have last minute changes to our talks and I always come in the conference with updated slides that I pass to the management team. The answer to that dilemma used to be working off memory sticks, and that worked not bad. However last year I started putting all the documents relating to a conference in a DropBox folder, and that works great too. Obviously DropBox works only if you have connectivity, so if I for instance update slides while on an international flight, I cannot save to the cloud. The obvious answer to that is to backup everything on a memory stick… but I have to admit, I have been trusting my luck and working off my laptop HD and then synching everything to the cloud after landing. Of course on some US national flights you get WiFi on board, so in that case it is even simpler :) Usually after the conference is done, I remove the files from DropBox and copy them to their "final destination". They are backed up from there to BackBlaze, the great online backup service I am using routinely (I currently have about 90GB of data in BackBlaze). Outlining the presentations I like to have a written outline of my presentations written somewhere. I keep it simple, just write the various sections of the presentation with timing. I guess it is a remnant of the time when I was a private pilot, and using checklists for flight preparation. For example: Demo about designability 15' (0:37) Switch to Blend Open MainPage.xaml Create a DataTemplate ... Here I can immediately see during the presentation if I am taking too much time for my demo (0:37 is where I need to be when I am done with this section of the presentation, and 15' is the time that this particular section takes). I keep these sections reasonable, I don't detail every step of the preparation. Typically I have one such section for every 10-15 minutes of my talks. Yes, I am timing my presentations. I keep adjusting these numbers when I rehearse, and this really helps to feel more confident during the presentations. This is especially important for presentations that are long, like my MIX11 demo which clocked at 57 minutes (I had a lot of stuff to show…). Such presentations are risky, because if anything goes wrong, you will have to cut stuff, so the answer to that is: Rehearse, rehearse and when you're done rehearsing, rehearse a little more. I also have a "Preparation" section where I outline what I need to do before a presentation. For instance: Preparation Reboot in VHD Make sure MSN and Twitter are not running. Open VS10 and load demo Open Blend and load demo Run the WP7 emulator ... I typically start preparing my laptop an hour before the talk, starting everything I need to start and then putting my laptop to sleep. Saving and printing the outline, Timing Printing is a real problem because it is really hard to find a printer at most conference venues, and also quite hard in hotels. To solve that, I simply write everything in OneNote (synched to the cloud, now you start to know what I like ;) and then I print it to a PDF (I use CutePDFWriter) that I save to my Kindle. During the presentation, I read the outline off the Kindle (I mostly just need a quick check to see how I am timing). For timing during the presentation, I use the free tool ChronoGPS on my Windows Phone 7, but of course any phone these days has a clock/chrono application. In some conferences, they even have timers that the presenters can see, but they tend to count down and I prefer to count up… so I just use my own :) Source control for demos For demos, I create a separate folder and use Mercurial as source control. Mercurial has the huge advantage (over SVN or TFS) to work offline too, so I can commit while on a plane, and all the history is saved. Then when I have connectivity I push everything to the cloud (I am using the fantastic Trunksapp.com for my private repositories). Here too the obvious downside is the risk of losing my last changes if my laptop crashes before I can push to the cloud, and here too the obvious answer would be to work from a memory stick… though I have to admit I didn't do that lately (except when I was writing Silverlight 4 Unleashed, where I was really paranoid…) And code snippets? I am one of these presenters who hates to type in front of an audience. I can type really fast (writing two books has this advantage, it really teaches you to touch type and be fast at it) but in the context of an audience, on a stage where it is often damn cold (an issue I had a lot in past conferences, air conditioning can freeze your fingers and make it really hard to type), it doesn't work as well. I don't know for you, but I really dislike seeing a presentation where the speaker uses the backspace key more often than others ;) To solve that, I like to have my code ready in snippets, and drag them to the screen. Then I can spend time explaining each code snippet, while highlighting portions of the code (always highlight what you talk about, the audience often doesn't even see the cursor and doesn't know where you are on the screen!) Over the years I have used various solutions for code snippets, and now I have one which works really well… if you take a few precautions! I use the Visual Studio Toolbox. Preparing the code snippets You can store code snippets in the Toolbox for anything, XAML, C# etc. I arrange the snippets in the order in which I need them, which is a great way to remember what comes next in the presentation. I also separate them by topic, to make it easier to find them, for example when I switch to the slides and then back to the code. Remember that no matter how experienced you are, you will feel more nervous on stage than while you are preparing, so any way to make it easier for you is going to be beneficial to the audience. To store a code snippet, I do the following: Open the final demo that you want to show to the audience in Visual Studio. In your code, select a snippet of code that you want to explain in particular. Make sure that the Visual Studio Toolbox is open (menu View, Toolbox or Ctrl-Alt-X). Drag the selected snippet from the code window to the toolbox. (if needed) drag the snippet to the correct location (for example between two other code snippets so that you can access it as you speak through the demo). Right click on the snippet and select Rename Item from the context menu. Select a meaningful name. For me I use the following conventions: If it is a method, I use the method's name. If it is not a whole method, I use a descriptive name. If it is the content of a method (i.e. the body only, without the method's signature), I use "-> MethodName". This reminds me during the presentation that this is only the body, and that I need to insert that into an existing signature. This is the case, for instance, when I use Visual Studio to automatically generate the members of an interface’s implementation; then I only need to insert my snippet inside the generated method body. Saving the snippets This is the most important!! It happened to me a few times that VS10 lost its settings. When that happens, the snippets are lost too! Yeah that really sucks, especially (as it happened once) when this is the case about an hour before a talk… Stress and sweat follows, not good conditions to start a talk in front of an audience believe me. Thankfully, saving snippets is really easy with the following steps: Select the menu Tools, Import and Export Settings. Select Export selected environment settings and press Next. Uncheck All Settings. Then expand General Settings and select Toolbox (only!). Press Next. Select your source control folder and save under a meaningful name (for instance Snippets.vssettings). Commit to source control and push to the cloud. By the way, this also has the advantage of applying source control to the snippets file (which is an XML file), so you get history for free on that file! Reimporting the snippets If VS loses its settings and you need to reimport the snippets, this can be done super easily and very fast. Make sure that the Toolbox is empty. When you import snippets, they are merged with existing ones, they do not replace the content of the Toolbox. Unless merging is really what you want, make sure that your Toolbox is clean before you import, it is really easier. Select the menu Tools, Import and Export Settings. Select Import selected environment settings and press Next. Select No, just import new settings and press Next. Press Browse and select the Snippets.vssettings file. Press Finish. Et voila, all your snippets appear again in the Toolbox. Whew, the worst was averted and you can start your demo without sweating! (I had to do that once literally 5 minutes before the start of a demo, while my laptop was already hooked to the projector, and it went just fine). What about special tools? When using special tools (for example beta versions of tools you have an early access to), or a special configuration of your laptop, things can get tricky because you cannot really be sure that you will get a laptop with the same tools and the same configuration at the conference. To solve that, I use the following precautions: I make my demos from a Virtual Hard Disk. The great John Papa made a very easy-to-follow web page where he explains how to create a VHD and install Win7 to it. This gives you the full power of your laptop (as fast as booting from the metal). For me, I have a basic configuration that I saved on a USB harddrive (Win7 plus drivers, basic settings for desktop, folder options, taskbar etc) and Visual Studio 2010 SP1 on it. When preparing, I start by copying this "basis VHD" to my laptop. I install additional tools and configurations. I save the VHD back to the USB harddrive in a different folder. This would allow me to reinstall my demo environment quite fast, for example in case of harddrive failure. Replace the harddrive, copy the VHD to it, configure the BCD and you can start. Unfortunately this only works if the laptop itself still works. In the worst case of total failure, my security is to back all the installers up: The installers I use are synched on all my laptops and backed up to BackBlaze. If the worst happens and my laptop is absolutely broken, I can download the installer from BackBlaze and install on another laptop. This of course takes some time, and if that happens 5 minutes before a presentation, well… I don't have an answer to that, except of course crossing my fingers. Still, all that gives me additional security. Conclusion Remember folks, talking to an audience, large or small, will make you nervous. Just ask Scott Hanselman :) The goal here is to create the best possible conditions for you, and to create an environment where everything is saved and easy to restore, where everything is well known and provides you with additional confidence. The cooler you feel before the presentation (and during ;)), the better your presentation will be. Here too, the goal is to provide the best user experience you can have, which in turn will make it more enjoyable for your audience! Happy presenting :) Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • iphone: Help with AudioToolbox Leak: Stack trace/code included here...

    - by editor guy
    Part of this app is a "Scream" button that plays random screams from cast members of a TV show. I have to bang on the app quite a while to see a memory leak in Instruments, but it's there, occasionally coming up (every 45 seconds to 2 minutes.) The leak is 3.50kb when it occurs. Haven't been able to crack it for several hours. Any help appreciated. Instruments says this is the offending code line: [appSoundPlayer play]; that's linked to from line 9 of the below stack trace: 0 libSystem.B.dylib malloc 1 libSystem.B.dylib pthread_create 2 AudioToolbox CAPThread::Start() 3 AudioToolbox GenericRunLoopThread::Start() 4 AudioToolbox AudioQueueNew(bool, AudioStreamBasicDescription const*, TCACallback const&, CACallbackTarget const&, unsigned long, OpaqueAudioQueue*) 5 AudioToolbox AudioQueueNewOutput 6 AVFoundation allocAudioQueue(AVAudioPlayer, AudioPlayerImpl*) 7 AVFoundation prepareToPlayQueue(AVAudioPlayer*, AudioPlayerImpl*) 8 AVFoundation -[AVAudioPlayer prepareToPlay] 9 Scream Queens -[ScreamViewController scream:] /Users/laptop2/Desktop/ScreamQueens Versions/ScreamQueens25/Scream Queens/Classes/../ScreamViewController.m:210 10 CoreFoundation -[NSObject performSelector:withObject:withObject:] 11 UIKit -[UIApplication sendAction:to:from:forEvent:] 12 UIKit -[UIApplication sendAction:toTarget:fromSender:forEvent:] 13 UIKit -[UIControl sendAction:to:forEvent:] 14 UIKit -[UIControl(Internal) _sendActionsForEvents:withEvent:] 15 UIKit -[UIControl touchesEnded:withEvent:] 16 UIKit -[UIWindow _sendTouchesForEvent:] 17 UIKit -[UIWindow sendEvent:] 18 UIKit -[UIApplication sendEvent:] 19 UIKit _UIApplicationHandleEvent 20 GraphicsServices PurpleEventCallback 21 CoreFoundation CFRunLoopRunSpecific 22 CoreFoundation CFRunLoopRunInMode 23 GraphicsServices GSEventRunModal 24 UIKit -[UIApplication _run] 25 UIKit UIApplicationMain 26 Scream Queens main /Users/laptop2/Desktop/ScreamQueens Versions/ScreamQueens25/Scream Queens/main.m:14 27 Scream Queens start Here's .h: #import <UIKit/UIKit.h> #import <AVFoundation/AVFoundation.h> #import <MediaPlayer/MediaPlayer.h> #import <AudioToolbox/AudioToolbox.h> #import <MessageUI/MessageUI.h> #import <MessageUI/MFMailComposeViewController.h> @interface ScreamViewController : UIViewController <UIApplicationDelegate, AVAudioPlayerDelegate, MFMailComposeViewControllerDelegate> { //AudioPlayer related AVAudioPlayer *appSoundPlayer; NSURL *soundFileURL; BOOL interruptedOnPlayback; BOOL playing; //Scream button related IBOutlet UIButton *screamButton; int currentScreamIndex; NSString *currentScream; NSMutableArray *screams; NSMutableArray *personScreaming; NSMutableArray *photoArray; int currentSayingsIndex; NSString *currentButtonSaying; NSMutableArray *funnyButtonSayings; IBOutlet UILabel *funnyButtonSayingsLabel; IBOutlet UILabel *personScreamingField; IBOutlet UIImageView *personScreamingImage; //Mailing the scream related IBOutlet UILabel *mailStatusMessage; IBOutlet UIButton *shareButton; } //AudioPlayer related @property (nonatomic, retain) AVAudioPlayer *appSoundPlayer; @property (nonatomic, retain) NSURL *soundFileURL; @property (readwrite) BOOL interruptedOnPlayback; @property (readwrite) BOOL playing; //Scream button related @property (nonatomic, retain) UIButton *screamButton; @property (nonatomic, retain) NSMutableArray *screams; @property (nonatomic, retain) NSMutableArray *personScreaming; @property (nonatomic, retain) NSMutableArray *photoArray; @property (nonatomic, retain) UILabel *personScreamingField; @property (nonatomic, retain) UIImageView *personScreamingImage; @property (nonatomic, retain) NSMutableArray *funnyButtonSayings; @property (nonatomic, retain) UILabel *funnyButtonSayingsLabel; //Mailing the scream related @property (nonatomic, retain) IBOutlet UILabel *mailStatusMessage; @property (nonatomic, retain) IBOutlet UIButton *shareButton; //Scream Button - (IBAction) scream: (id) sender; //Mail the scream - (IBAction) showPicker: (id)sender; - (void)displayComposerSheet; - (void)launchMailAppOnDevice; @end Here's the top of .m: #import "ScreamViewController.h" //top of code has Audio session callback function for responding to audio route changes (from Apple's code), then my code continues... @implementation ScreamViewController @synthesize appSoundPlayer; // AVAudioPlayer object for playing the selected scream @synthesize soundFileURL; // Path to the scream @synthesize interruptedOnPlayback; // Was application interrupted during audio playback @synthesize playing; // Track playing/not playing state @synthesize screamButton; //Press this button, girls scream. @synthesize screams; //Mutable array holding strings pointing to sound files of screams. @synthesize personScreaming; //Mutable array tracking the person doing the screaming @synthesize photoArray; //Mutable array holding strings pointing to photos of screaming girls @synthesize personScreamingField; //Field updates to announce which girl is screaming. @synthesize personScreamingImage; //Updates to show image of the screamer. @synthesize funnyButtonSayings; //Mutable array holding the sayings @synthesize funnyButtonSayingsLabel; //Label that updates with the funnyButtonSayings @synthesize mailStatusMessage; //did the email go out @synthesize shareButton; //share scream via email Next line begins the block with the offending code: - (IBAction) scream: (id) sender { //Play a click sound effect SystemSoundID soundID; NSString *sfxPath = [[NSBundle mainBundle] pathForResource:@"aClick" ofType:@"caf"]; AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:sfxPath],&soundID); AudioServicesPlaySystemSound (soundID); // Because someone may slam the scream button over and over, //must stop current sound, then begin next if ([self appSoundPlayer] != nil) { [[self appSoundPlayer] setDelegate:nil]; [[self appSoundPlayer] stop]; [self setAppSoundPlayer: nil]; } //after selecting a random index in the array (did that in View Did Load), //we move to the next scream on each click. //First check... //Are we past the end of the array? if (currentScreamIndex == [screams count]) { currentScreamIndex = 0; } //Get the string at the index in the personScreaming array currentScream = [screams objectAtIndex: currentScreamIndex]; //Get the string at the index in the personScreaming array NSString *screamer = [personScreaming objectAtIndex:currentScreamIndex]; //Log the string to the console NSLog (@"playing scream: %@", screamer); // Display the string in the personScreamingField field NSString *listScreamer = [NSString stringWithFormat:@"scream by: %@", screamer]; [personScreamingField setText:listScreamer]; // Gets the file system path to the scream to play. NSString *soundFilePath = [[NSBundle mainBundle] pathForResource: currentScream ofType: @"caf"]; // Converts the sound's file path to an NSURL object NSURL *newURL = [[NSURL alloc] initFileURLWithPath: soundFilePath]; self.soundFileURL = newURL; [newURL release]; [[AVAudioSession sharedInstance] setDelegate: self]; [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error: nil]; // Registers the audio route change listener callback function AudioSessionAddPropertyListener ( kAudioSessionProperty_AudioRouteChange, audioRouteChangeListenerCallback, self ); // Activates the audio session. NSError *activationError = nil; [[AVAudioSession sharedInstance] setActive: YES error: &activationError]; // Instantiates the AVAudioPlayer object, initializing it with the sound AVAudioPlayer *newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL: soundFileURL error: nil]; //Error check and continue if (newPlayer != nil) { self.appSoundPlayer = newPlayer; [newPlayer release]; [appSoundPlayer prepareToPlay]; [appSoundPlayer setVolume: 1.0]; [appSoundPlayer setDelegate:self]; //NEXT LINE IS FLAGGED BY INSTRUMENTS AS LEAKY [appSoundPlayer play]; playing = YES; //Get the string at the index in the photoArray array NSString *screamerPic = [photoArray objectAtIndex:currentScreamIndex]; //Log the string to the console NSLog (@"displaying photo: %@", screamerPic); // Display the image of the person screaming personScreamingImage.image = [UIImage imageNamed:screamerPic]; //show the share button shareButton.hidden = NO; mailStatusMessage.hidden = NO; mailStatusMessage.text = @"share!"; //Get the string at the index in the funnySayings array currentSayingsIndex = random() % [funnyButtonSayings count]; currentButtonSaying = [funnyButtonSayings objectAtIndex: currentSayingsIndex]; NSString *theSaying = [funnyButtonSayings objectAtIndex:currentSayingsIndex]; [funnyButtonSayingsLabel setText: theSaying]; currentScreamIndex++; } } Here's my dealloc: - (void)dealloc { [appSoundPlayer stop]; [appSoundPlayer release], appSoundPlayer = nil; [screamButton release], screamButton = nil; [mailStatusMessage release], mailStatusMessage = nil; [personScreamingField release], personScreamingField = nil; [personScreamingImage release], personScreamingImage = nil; [funnyButtonSayings release], funnyButtonSayings = nil; [funnyButtonSayingsLabel release], funnyButtonSayingsLabel = nil; [screams release], screams = nil; [personScreaming release], personScreaming = nil; [soundFileURL release]; [super dealloc]; } @end Thanks so much for reading this far! Any input appreciated.

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  • creating objects from trivial graph format text file. java. dijkstra algorithm.

    - by user560084
    i want to create objects, vertex and edge, from trivial graph format txt file. one of programmers here suggested that i use trivial graph format to store data for dijkstra algorithm. the problem is that at the moment all the information, e.g., weight, links, is in the sourcecode. i want to have a separate text file for that and read it into the program. i thought about using a code for scanning through the text file by using scanner. but i am not quite sure how to create different objects from the same file. could i have some help please? the file is v0 Harrisburg v1 Baltimore v2 Washington v3 Philadelphia v4 Binghamton v5 Allentown v6 New York # v0 v1 79.83 v0 v5 81.15 v1 v0 79.75 v1 v2 39.42 v1 v3 103.00 v2 v1 38.65 v3 v1 102.53 v3 v5 61.44 v3 v6 96.79 v4 v5 133.04 v5 v0 81.77 v5 v3 62.05 v5 v4 134.47 v5 v6 91.63 v6 v3 97.24 v6 v5 87.94 and the dijkstra algorithm code is Downloaded from: http://en.literateprograms.org/Special:Downloadcode/Dijkstra%27s_algorithm_%28Java%29 */ import java.util.PriorityQueue; import java.util.List; import java.util.ArrayList; import java.util.Collections; class Vertex implements Comparable<Vertex> { public final String name; public Edge[] adjacencies; public double minDistance = Double.POSITIVE_INFINITY; public Vertex previous; public Vertex(String argName) { name = argName; } public String toString() { return name; } public int compareTo(Vertex other) { return Double.compare(minDistance, other.minDistance); } } class Edge { public final Vertex target; public final double weight; public Edge(Vertex argTarget, double argWeight) { target = argTarget; weight = argWeight; } } public class Dijkstra { public static void computePaths(Vertex source) { source.minDistance = 0.; PriorityQueue<Vertex> vertexQueue = new PriorityQueue<Vertex>(); vertexQueue.add(source); while (!vertexQueue.isEmpty()) { Vertex u = vertexQueue.poll(); // Visit each edge exiting u for (Edge e : u.adjacencies) { Vertex v = e.target; double weight = e.weight; double distanceThroughU = u.minDistance + weight; if (distanceThroughU < v.minDistance) { vertexQueue.remove(v); v.minDistance = distanceThroughU ; v.previous = u; vertexQueue.add(v); } } } } public static List<Vertex> getShortestPathTo(Vertex target) { List<Vertex> path = new ArrayList<Vertex>(); for (Vertex vertex = target; vertex != null; vertex = vertex.previous) path.add(vertex); Collections.reverse(path); return path; } public static void main(String[] args) { Vertex v0 = new Vertex("Nottinghill_Gate"); Vertex v1 = new Vertex("High_Street_kensignton"); Vertex v2 = new Vertex("Glouchester_Road"); Vertex v3 = new Vertex("South_Kensignton"); Vertex v4 = new Vertex("Sloane_Square"); Vertex v5 = new Vertex("Victoria"); Vertex v6 = new Vertex("Westminster"); v0.adjacencies = new Edge[]{new Edge(v1, 79.83), new Edge(v6, 97.24)}; v1.adjacencies = new Edge[]{new Edge(v2, 39.42), new Edge(v0, 79.83)}; v2.adjacencies = new Edge[]{new Edge(v3, 38.65), new Edge(v1, 39.42)}; v3.adjacencies = new Edge[]{new Edge(v4, 102.53), new Edge(v2, 38.65)}; v4.adjacencies = new Edge[]{new Edge(v5, 133.04), new Edge(v3, 102.53)}; v5.adjacencies = new Edge[]{new Edge(v6, 81.77), new Edge(v4, 133.04)}; v6.adjacencies = new Edge[]{new Edge(v0, 97.24), new Edge(v5, 81.77)}; Vertex[] vertices = { v0, v1, v2, v3, v4, v5, v6 }; computePaths(v0); for (Vertex v : vertices) { System.out.println("Distance to " + v + ": " + v.minDistance); List<Vertex> path = getShortestPathTo(v); System.out.println("Path: " + path); } } } and the code for scanning file is import java.util.Scanner; import java.io.File; import java.io.FileNotFoundException; public class DataScanner1 { //private int total = 0; //private int distance = 0; private String vector; private String stations; private double [] Edge = new double []; /*public int getTotal(){ return total; } */ /* public void getMenuInput(){ KeyboardInput in = new KeyboardInput; System.out.println("Enter the destination? "); String val = in.readString(); return val; } */ public void readFile(String fileName) { try { Scanner scanner = new Scanner(new File(fileName)); scanner.useDelimiter (System.getProperty("line.separator")); while (scanner.hasNext()) { parseLine(scanner.next()); } scanner.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } } public void parseLine(String line) { Scanner lineScanner = new Scanner(line); lineScanner.useDelimiter("\\s*,\\s*"); vector = lineScanner.next(); stations = lineScanner.next(); System.out.println("The current station is " + vector + " and the destination to the next station is " + stations + "."); //total += distance; //System.out.println("The total distance is " + total); } public static void main(String[] args) { /* if (args.length != 1) { System.err.println("usage: java TextScanner2" + "file location"); System.exit(0); } */ DataScanner1 scanner = new DataScanner1(); scanner.readFile(args[0]); //int total =+ distance; //System.out.println(""); //System.out.println("The total distance is " + scanner.getTotal()); } }

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  • YouTube API Security Error Flex

    - by 23tux
    Hi, I've tried to use the YoutTube API within a Flex project. But i got this error: *** Security Sandbox Violation *** SecurityDomain 'http://www.youtube.com/apiplayer?version=3' tried to access incompatible context 'file:///Users/YouTubePlayer/bin-debug/YouTubePlayer.html' Here are the two files: <?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/halo" minWidth="1024" minHeight="768" xmlns:youtube="youtube.*" creationComplete="init();"> <fx:Script> <![CDATA[ [Bindable] private var ready:Boolean = true; private function init():void { Security.allowInsecureDomain("*"); Security.allowDomain("*"); Security.allowDomain('www.youtube.com'); Security.allowDomain('youtube.com'); Security.allowDomain('s.ytimg.com'); Security.allowDomain('i.ytimg.com'); } private function changing():void { /* trace("currentTime: " + player.getCurrentTime()); trace("startTime: " + player.startTime); trace("stopTime: " + player.stopTime); timeSlider.value = player.getCurrentTime() */ } private function startPlaying():void { player.play(); } private function checkStartSlider():void { if(startSlider.value > stopSlider.value) stopSlider.value = startSlider.value + 1; } private function checkStopSlider():void { if(stopSlider.value < startSlider.value) startSlider.value = stopSlider.value - 1; } ]]> </fx:Script> <s:VGroup> <youtube:Player id="player" videoID="DVFvcVuWyfE" change="changing();" ready="ready=true"/> <s:HGroup> <s:Button label="play" click="startPlaying();" /> </s:HGroup> <s:HGroup> <s:HSlider id="timeSlider" width="250" minimum="0" maximum="{player.stopTime}" snapInterval=".01" enabled="{ready}"/> <s:Label id="currentTimeLbl" text="current time: 0" /> </s:HGroup> <s:HGroup> <s:HSlider id="startSlider" width="250" minimum="0" maximum="{player.stopTime}" snapInterval=".01" change="checkStartSlider();" enabled="{ready}" value="0"/> <s:Label id="startTimeLbl" text="start time: {player.startTime}" /> </s:HGroup> <s:HGroup> <s:HSlider id="stopSlider" width="250" minimum="0" maximum="{player.stopTime}" snapInterval=".01" change="checkStopSlider();" enabled="{ready}" value="{player.stopTime}"/> <s:Label id="stopTimeLbl" text="stop time: {player.stopTime}" /> </s:HGroup> </s:VGroup> </s:Application> Here is the player package youtube { import flash.display.Loader; import flash.events.Event; import flash.events.TimerEvent; import flash.net.URLRequest; import flash.system.Security; import flash.utils.Timer; import mx.core.UIComponent; [Event(name="change", type="flash.events.Event")] [Event(name="ready", type="flash.events.Event")] public class Player extends UIComponent { private var player:Object; private var loader:Loader; private var _startTime:Number = 0; private var _stopTime:Number = 0; private var _videoID:String; private var metadataTimer:Timer = new Timer(200); private var playTimer:Timer = new Timer(200); public function Player() { // The player SWF file on www.youtube.com needs to communicate with your host // SWF file. Your code must call Security.allowDomain() to allow this // communication. Security.allowInsecureDomain("*"); Security.allowDomain("*"); // This will hold the API player instance once it is initialized. loader = new Loader(); loader.contentLoaderInfo.addEventListener(Event.INIT, onLoaderInit); loader.load(new URLRequest("http://www.youtube.com/apiplayer?version=3")); } private function onLoaderInit(event:Event):void { addChild(loader); loader.content.addEventListener("onReady", onPlayerReady); loader.content.addEventListener("onError", onPlayerError); loader.content.addEventListener("onStateChange", onPlayerStateChange); loader.content.addEventListener("onPlaybackQualityChange", onVideoPlaybackQualityChange); } private function onPlayerReady(event:Event):void { // Event.data contains the event parameter, which is the Player API ID trace("player ready:", Object(event).data); // Once this event has been dispatched by the player, we can use // cueVideoById, loadVideoById, cueVideoByUrl and loadVideoByUrl // to load a particular YouTube video. player = loader.content; // Set appropriate player dimensions for your application player.setSize(0, 0); } private function onPlayerError(event:Event):void { // Event.data contains the event parameter, which is the error code trace("player error:", Object(event).data); } private function onPlayerStateChange(event:Event):void { // Event.data contains the event parameter, which is the new player state trace("player state:", Object(event).data); } private function onVideoPlaybackQualityChange(event:Event):void { // Event.data contains the event parameter, which is the new video quality trace("video quality:", Object(event).data); } [Bindable] public function get videoID():String { return _videoID; } public function set videoID(value:String):void { _videoID = value; } [Bindable] public function get stopTime():Number { return _stopTime; } public function set stopTime(value:Number):void { _stopTime = value; } [Bindable] public function get startTime():Number { return _startTime; } public function set startTime(value:Number):void { _startTime = value; } public function play():void { if(_videoID!="") { player.loadVideoById(_videoID, 0); // add the event listener, so that all 200 milliseconds is an event dispatched metadataTimer.addEventListener(TimerEvent.TIMER, metadataTimeHandler); // if the timer is running, stop and reset it if(metadataTimer.running) metadataTimer.reset(); else metadataTimer.start(); } } private function metadataTimeHandler(e:TimerEvent):void { if(player.getDuration() > 0) { startTime = 0; stopTime = player.getDuration(); metadataTimer.reset(); metadataTimer.stop(); metadataTimer.removeEventListener(TimerEvent.TIMER, metadataTimeHandler); player.playVideo(); playTimer.addEventListener(TimerEvent.TIMER, playTimerHandler); dispatchEvent(new Event("ready")); } } private function playTimerHandler(e:TimerEvent):void { if(getCurrentTime() > _stopTime) { seekTo(startTime); } dispatchEvent(new Event(Event.CHANGE)); } public function getCurrentTime():Number { if(!player.getCurrentTime()) return 0; else return player.getCurrentTime(); } public function seekTo(time:uint):void { player.seekTo(time); } } } Hope someone can help. thx, tux

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  • Solving embarassingly parallel problems using Python multiprocessing

    - by gotgenes
    How does one use multiprocessing to tackle embarrassingly parallel problems? Embarassingly parallel problems typically consist of three basic parts: Read input data (from a file, database, tcp connection, etc.). Run calculations on the input data, where each calculation is independent of any other calculation. Write results of calculations (to a file, database, tcp connection, etc.). We can parallelize the program in two dimensions: Part 2 can run on multiple cores, since each calculation is independent; order of processing doesn't matter. Each part can run independently. Part 1 can place data on an input queue, part 2 can pull data off the input queue and put results onto an output queue, and part 3 can pull results off the output queue and write them out. This seems a most basic pattern in concurrent programming, but I am still lost in trying to solve it, so let's write a canonical example to illustrate how this is done using multiprocessing. Here is the example problem: Given a CSV file with rows of integers as input, compute their sums. Separate the problem into three parts, which can all run in parallel: Process the input file into raw data (lists/iterables of integers) Calculate the sums of the data, in parallel Output the sums Below is traditional, single-process bound Python program which solves these three tasks: #!/usr/bin/env python # -*- coding: UTF-8 -*- # basicsums.py """A program that reads integer values from a CSV file and writes out their sums to another CSV file. """ import csv import optparse import sys def make_cli_parser(): """Make the command line interface parser.""" usage = "\n\n".join(["python %prog INPUT_CSV OUTPUT_CSV", __doc__, """ ARGUMENTS: INPUT_CSV: an input CSV file with rows of numbers OUTPUT_CSV: an output file that will contain the sums\ """]) cli_parser = optparse.OptionParser(usage) return cli_parser def parse_input_csv(csvfile): """Parses the input CSV and yields tuples with the index of the row as the first element, and the integers of the row as the second element. The index is zero-index based. :Parameters: - `csvfile`: a `csv.reader` instance """ for i, row in enumerate(csvfile): row = [int(entry) for entry in row] yield i, row def sum_rows(rows): """Yields a tuple with the index of each input list of integers as the first element, and the sum of the list of integers as the second element. The index is zero-index based. :Parameters: - `rows`: an iterable of tuples, with the index of the original row as the first element, and a list of integers as the second element """ for i, row in rows: yield i, sum(row) def write_results(csvfile, results): """Writes a series of results to an outfile, where the first column is the index of the original row of data, and the second column is the result of the calculation. The index is zero-index based. :Parameters: - `csvfile`: a `csv.writer` instance to which to write results - `results`: an iterable of tuples, with the index (zero-based) of the original row as the first element, and the calculated result from that row as the second element """ for result_row in results: csvfile.writerow(result_row) def main(argv): cli_parser = make_cli_parser() opts, args = cli_parser.parse_args(argv) if len(args) != 2: cli_parser.error("Please provide an input file and output file.") infile = open(args[0]) in_csvfile = csv.reader(infile) outfile = open(args[1], 'w') out_csvfile = csv.writer(outfile) # gets an iterable of rows that's not yet evaluated input_rows = parse_input_csv(in_csvfile) # sends the rows iterable to sum_rows() for results iterable, but # still not evaluated result_rows = sum_rows(input_rows) # finally evaluation takes place as a chain in write_results() write_results(out_csvfile, result_rows) infile.close() outfile.close() if __name__ == '__main__': main(sys.argv[1:]) Let's take this program and rewrite it to use multiprocessing to parallelize the three parts outlined above. Below is a skeleton of this new, parallelized program, that needs to be fleshed out to address the parts in the comments: #!/usr/bin/env python # -*- coding: UTF-8 -*- # multiproc_sums.py """A program that reads integer values from a CSV file and writes out their sums to another CSV file, using multiple processes if desired. """ import csv import multiprocessing import optparse import sys NUM_PROCS = multiprocessing.cpu_count() def make_cli_parser(): """Make the command line interface parser.""" usage = "\n\n".join(["python %prog INPUT_CSV OUTPUT_CSV", __doc__, """ ARGUMENTS: INPUT_CSV: an input CSV file with rows of numbers OUTPUT_CSV: an output file that will contain the sums\ """]) cli_parser = optparse.OptionParser(usage) cli_parser.add_option('-n', '--numprocs', type='int', default=NUM_PROCS, help="Number of processes to launch [DEFAULT: %default]") return cli_parser def main(argv): cli_parser = make_cli_parser() opts, args = cli_parser.parse_args(argv) if len(args) != 2: cli_parser.error("Please provide an input file and output file.") infile = open(args[0]) in_csvfile = csv.reader(infile) outfile = open(args[1], 'w') out_csvfile = csv.writer(outfile) # Parse the input file and add the parsed data to a queue for # processing, possibly chunking to decrease communication between # processes. # Process the parsed data as soon as any (chunks) appear on the # queue, using as many processes as allotted by the user # (opts.numprocs); place results on a queue for output. # # Terminate processes when the parser stops putting data in the # input queue. # Write the results to disk as soon as they appear on the output # queue. # Ensure all child processes have terminated. # Clean up files. infile.close() outfile.close() if __name__ == '__main__': main(sys.argv[1:]) These pieces of code, as well as another piece of code that can generate example CSV files for testing purposes, can be found on github. I would appreciate any insight here as to how you concurrency gurus would approach this problem. Here are some questions I had when thinking about this problem. Bonus points for addressing any/all: Should I have child processes for reading in the data and placing it into the queue, or can the main process do this without blocking until all input is read? Likewise, should I have a child process for writing the results out from the processed queue, or can the main process do this without having to wait for all the results? Should I use a processes pool for the sum operations? If yes, what method do I call on the pool to get it to start processing the results coming into the input queue, without blocking the input and output processes, too? apply_async()? map_async()? imap()? imap_unordered()? Suppose we didn't need to siphon off the input and output queues as data entered them, but could wait until all input was parsed and all results were calculated (e.g., because we know all the input and output will fit in system memory). Should we change the algorithm in any way (e.g., not run any processes concurrently with I/O)?

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  • problem in concurrent web services

    - by user548750
    Hi All I have developed a web services. I am getting problem when two different user are trying to access web services concurrently. In web services two methods are there setInputParameter getUserService suppose Time User Operation 10:10 am user1 setInputParameter 10:15 am user2 setInputParameter 10:20 am user1 getUserService User1 is getting result according to the input parameter seted by user2 not by ( him own ) I am using axis2 1.4 ,eclipse ant build, My services are goes here User class service class service.xml build file testclass package com.jimmy.pojo; public class User { private String firstName; private String lastName; private String[] addressCity; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String[] getAddressCity() { return addressCity; } public void setAddressCity(String[] addressCity) { this.addressCity = addressCity; } } [/code] [code=java]package com.jimmy.service; import com.jimmy.pojo.User; public class UserService { private User user; public void setInputParameter(User userInput) { user = userInput; } public User getUserService() { user.setFirstName(user.getFirstName() + " changed "); if (user.getAddressCity() == null) { user.setAddressCity(new String[] { "New City Added" }); } else { user.getAddressCity()[0] = "==========="; } return user; } } [/code] [code=java]<service name="MyWebServices" scope="application"> <description> My Web Service </description> <messageReceivers> <messageReceiver mep="http://www.w3.org/2004/08/wsdl/in-only" class="org.apache.axis2.rpc.receivers.RPCInOnlyMessageReceiver" /> <messageReceiver mep="http://www.w3.org/2004/08/wsdl/in-out" class="org.apache.axis2.rpc.receivers.RPCMessageReceiver" /> </messageReceivers> <parameter name="ServiceClass">com.jimmy.service.UserService </parameter> </service>[/code] [code=java] <project name="MyWebServices" basedir="." default="generate.service"> <property name="service.name" value="UserService" /> <property name="dest.dir" value="build" /> <property name="dest.dir.classes" value="${dest.dir}/${service.name}" /> <property name="dest.dir.lib" value="${dest.dir}/lib" /> <property name="axis2.home" value="../../" /> <property name="repository.path" value="${axis2.home}/repository" /> <path id="build.class.path"> <fileset dir="${axis2.home}/lib"> <include name="*.jar" /> </fileset> </path> <path id="client.class.path"> <fileset dir="${axis2.home}/lib"> <include name="*.jar" /> </fileset> <fileset dir="${dest.dir.lib}"> <include name="*.jar" /> </fileset> </path> <target name="clean"> <delete dir="${dest.dir}" /> <delete dir="src" includes="com/jimmy/pojo/stub/**"/> </target> <target name="prepare"> <mkdir dir="${dest.dir}" /> <mkdir dir="${dest.dir}/lib" /> <mkdir dir="${dest.dir.classes}" /> <mkdir dir="${dest.dir.classes}/META-INF" /> </target> <target name="generate.service" depends="clean,prepare"> <copy file="src/META-INF/services.xml" tofile="${dest.dir.classes}/META-INF/services.xml" overwrite="true" /> <javac srcdir="src" destdir="${dest.dir.classes}" includes="com/jimmy/service/**,com/jimmy/pojo/**"> <classpath refid="build.class.path" /> </javac> <jar basedir="${dest.dir.classes}" destfile="${dest.dir}/${service.name}.aar" /> <copy file="${dest.dir}/${service.name}.aar" tofile="${repository.path}/services/${service.name}.aar" overwrite="true" /> </target> </project> [/code] [code=java]package com.jimmy.test; import javax.xml.namespace.QName; import org.apache.axis2.AxisFault; import org.apache.axis2.addressing.EndpointReference; import org.apache.axis2.client.Options; import org.apache.axis2.rpc.client.RPCServiceClient; import com.jimmy.pojo.User; public class MyWebServices { @SuppressWarnings("unchecked") public static void main(String[] args1) throws AxisFault { RPCServiceClient serviceClient = new RPCServiceClient(); Options options = serviceClient.getOptions(); EndpointReference targetEPR = new EndpointReference( "http://localhost:8080/axis2/services/MyWebServices"); options.setTo(targetEPR); // Setting the Input Parameter QName opSetQName = new QName("http://service.jimmy.com", "setInputParameter"); User user = new User(); String[] cityList = new String[] { "Bangalore", "Mumbai" }; /* We need to set this for user 2 as user 2 */ user.setFirstName("User 1 first name"); user.setLastName("User 1 Last name"); user.setAddressCity(cityList); Object[] opSetInptArgs = new Object[] { user }; serviceClient.invokeRobust(opSetQName, opSetInptArgs); // Getting the weather QName opGetWeather = new QName("http://service.jimmy.com", "getUserService"); Object[] opGetWeatherArgs = new Object[] {}; Class[] returnTypes = new Class[] { User.class }; Object[] response = serviceClient.invokeBlocking(opGetWeather, opGetWeatherArgs, returnTypes); System.out.println("Context :"+serviceClient.getServiceContext()); User result = (User) response[0]; if (result == null) { System.out.println("User is not initialized!"); return; } else { System.out.println("*********printing result********"); String[] list =result.getAddressCity(); System.out.println(result.getFirstName()); System.out.println(result.getLastName()); for (int indx = 0; indx < list.length ; indx++) { String string = result.getAddressCity()[indx]; System.out.println(string); } } } }

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