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  • Looking for a fast hash-function.

    - by Julian
    Hello, I'm looking for a special hash-function. Let's say I have a large list of strings, if I order them by their hash-values they should be ordered quasi randomly. The most important point is: it must be super fast. I've tried md5 and sha1 and they're using to much cpu power. Clashes are not a problem. I'm using javascript, so it shouldn't be too complicated to implement.

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  • Strange phantom header margin bug html/css

    - by MickyJimbo
    So I'm creating this website and there is a strange untraceable bug that causes the header to move down 10 or so pixels. On a refresh the header could be correct or it could be broken. I've been testing it on Adobe Browserlab and the results are different every time.There is no discernible pattern making it incredible hard to track down. http://www.freeimagehosting.net/uploads/c866bf594d.jpg Has anyone ever had this problem and been able to fix it?

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  • PHP, MySQL - would results-array shuffle be quicker than "select... order by rand()"?

    - by sombe
    I've been reading a lot about the disadvantages of using "order by rand" so I don't need update on that. I was thinking, since I only need a limited amount of rows retrieved from the db to be randomized, maybe I should do: $r = $db->query("select * from table limit 500"); for($i;$i<500;$i++) $arr[$i]=mysqli_fetch_assoc($r); shuffle($arr); (i know this only randomizes the 500 first rows, be it). would that be faster than $r = $db->("select * from table order by rand() limit 500"); let me just mention, say the db tables were packed with more than...10,000 rows. why don't you do it yourself?!? - well, i have, but i'm looking for your experienced opinion. thanks!

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  • String generator issue

    - by Andrey
    I want to write a method which returns a string. So far so good. The creation of the string however is quite complicated. I have 3 string lists - the first one has 155 entries, the second one - 9, the third one 21. I want my method if called enough times(155*9*21) to return all the possible combinations of values from the 3 lists (basically this method should keep count on how many times it was called and return only one combination each time). Any ideas how to accomplish that? I have 155*9*22 possible combinations. The first time the method is called it should take List1(0), List2(0), List3(0). After that in the next 21 iterations, the index of the third list is only changed. Once all the elements from the third list have been used increment the index of the second list and so on. Once the method has produced all the possible combinations (155*9*22) I want it to start from the beginning.

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  • Latest stream cipher considered reasonably secure & easy to implement?

    - by hythlodayr
    (A)RC4 used to fit the bill, since it was so simple to write. But it's also less-than-secure these days. I'm wondering if there's a successor that's: Code is small enough to write & debug within an hour or so, using pseudo code as a template. Still considered secure, as of 2010. Optimized for software. Not encumbered by licensing issues. I can't use crypto libraries, otherwise all of this would be moot. Also, I'll consider block algorithms though I think most are pretty hefty. Thanks.

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  • Any tools can randomly generate the source code according to a language grammar?

    - by wbsun
    A C program source code can be parsed according to the C grammar(described in CFG) and eventually turned into many ASTs. I am considering if such tool exists: it can do the reverse thing by firstly randomly generating many ASTs, which include tokens that don't have the concrete string values, just the types of the tokens, according to the CFG, then generating the concrete tokens according to the tokens' definitions in the regular expression. I can imagine the first step looks like an iterative non-terminals replacement, which is randomly and can be limited by certain number of iteration times. The second step is just generating randomly strings according to regular expressions. Is there any tool that can do this?

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  • Silverlight 4 Training Kit

    - by ScottGu
    We recently released a new free Silverlight 4 Training Kit that walks you through building business applications with Silverlight 4.  You can browse the training kit online or alternatively download an entire offline version of the training kit.  The training material is structured on teaching how to use the new Silverlight 4 features to build an end to end business application. The training kit includes 8 modules, 25 videos, and several hands on labs. Below is a breakdown and links to all of the content. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Module 1: Introduction Click here to watch this module. In this video John Papa and Ian Griffiths discuss the key areas that the Building Business Applications with Silverlight 4 course focuses on. This module is the overview of the course and covers many key scenarios that are faced when building business applications, and how Silverlight can help address them. Module 2: WCF RIA Services Click here to explore this module. In this lab, you will create a web site for managing conferences that will be the basis for the other labs in this course. Don’t worry if you don’t complete a particular lab in the series – all lab manual instructions are accompanied by completed solutions, so you can either build your own solution from start to finish, or dive straight in at any point using the solutions provided as a starting point. In this lab you will learn how to set up WCF RIA Services, create bindings to the domain context, filter using the domain data source, and create domain service queries. Online Link Download Source Download Lab Document Videos Module 2.1 - WCF RIA Services Ian Griffiths sets up the Entity Framework and WCF RIA Services for the sample Event Manager application for the course. He covers how to set up the services, how the Domain Services work and the role that the DomainContext plays in the sample application. He also reviews the metadata classes and integrating the navigation framework. Module 2.2 – Using WCF RIA Services to Edit Entities Ian Griffiths discusses how he adds the ability to edit and create individual entities with the features built into WCF RIA Services into the sample Event Manager application. He covers data binding fundamentals, IQueryable, LINQ, the DomainDataSource, navigation to a single entity using the navigation framework, and how to use the Visual Studio designer to do much of the work . Module 2.3 – Showing Master/Details Records Using WCF RIA Services Ian Griffiths reviews how to display master/detail records for the sample Event Manager application using WCF RIA Services. He covers how to use the Include attribute to indicate which elements to serialize back to the client. Ian also demonstrates how to use the Data Sources window in the designer to add and bind controls to specific data elements. He wraps up by showing how to create custom services to the Domain Services. Module 3 – Authentication, Validation, MVVM, Commands, Implicit Styles and RichTextBox Click here to visit this module. This lab demonstrates how to build a login screen, integrate ASP.NET authentication, and perform validation on data elements. Model-View-ViewModel (MVVM) is introduced and used in this lab as a pattern to help separate the UI and business logic. You will also learn how to use implicit styling and the new RichTextBox control. Online Link Download Source Download Lab Document Videos Module 3.1 – Authentication Ian Griffiths covers how to integrate a login screen and authentication into the sample Event Manager application. Ian shows how to use the ASP.NET authentication and integrate it into WCF RIA Services and the Silverlight presentation layer. Module 3.2 – MVVM Ian Griffiths covers how to Model-View-ViewModel (MVVM) patterns into the sample Event Manager application. He discusses why MVVM exists, what separated presentation means, and why it is important. He shows how to connect the View to the ViewModel, why data binding is important in this symbiosis, and how everything fits together in the overall application. Module 3.3 –Validation Ian Griffiths discusses how validation of user input can be integrated into the sample Event Manager application. He demonstrates how to use the DataAnnotations, the INotifyDataErrorInfo interface, binding markup extensions, and WCF RIA Services in concert to achieve great validation in the sample application. He discusses how this technique allows for property level validation, entity level validation, and asynchronous server side validation. Module 3.4 – Implicit Styles Ian Griffiths discusses how why implicit styles are important and how they can be integrated into the sample Event Manager application. He shows how implicit styles defined in a resource dictionary can be applied to all elements of a particular kind throughout the application. Module 3.5 – RichTextBox Ian Griffiths discusses how the new RichTextBox control and it can be integrated into the sample Event Manager application. He demonstrates how the RichTextBox can provide editing for the event information and how it can display the rich text for selection and copying. Module 4 – User Profiles, Drop Targets, Webcam and Clipboard Click here to visit this module. This lab builds new features into the sample application to take the user's photo. It teaches you how to use the webcam to capture an image, use Silverlight as a drop target, and take advantage of programmatic access to the clipboard. Link Download Source Download Lab Document Videos Module 4.1 – Webcam Ian Griffiths demonstrates how the webcam adds value to the sample Event Manager application by capturing an image of the attendee. He discusses the VideoCaptureDevice, the CaptureDviceConfiguration, and the CaptureSource classes and how they allow audio and video to be captured so you can grab an image from the capture device and save it. Module 4.2 - Drag and Drop in Silverlight Ian Griffiths demonstrates how to capture and handle the Drop in the sample Event Manager application so the user can drag a photo from a file and drop it into the application. Ian reviews the AllowDrop property, the Drop event, how to access the file that can be dropped, and the other drag related events. He also reviews how to make this work across browsers and the challenges for this. Module 5 – Schedule Planner and Right Mouse Click Click here to visit this module. This lab builds on the application to allow grouping in the DataGrid and implement right mouse click features to add context menu support. Link Download Source Download Lab Document Videos Module 5.1 – Grouping and Binding Ian Griffiths demonstrates how to use the grouping features for data binding in the DataGrid and how it applies to the sample Event Manager application. He reviews the role of the CollectionViewSource in grouping, customizing the templates for headers, and how to work with grouping with ItemsControls. Module 5.2 – Layout Visual States Ian Griffiths demonstrates how to use the Fluid UI animation support for visual states in the ListBox control DataGrid and how it applies to the sample Event Manager application. He reviews the 3 visual states of BeforeLoaded, AfterLoaded, and BeforeUnloaded. Module 5.3 – Right Mouse Click Ian Griffiths demonstrates how to add support for handling the right mouse button click event to display a context menu for the Event Manager application. He demonstrates how to handle the event, show a custom context menu control, and integrate it into the scheduling portion of the application. Module 6 – Printing the Schedule Click here to visit this module. This lab teaches how to use the new printing features in Silverlight 4. The lab walks through the PrintDocument class and the ViewBox control, while showing how to print multiple pages of content using them. Link Download Source Download Lab Document Videos Module 6.1 – Printing and the Viewbox Ian Griffiths demonstrates how to add the ability to print the schedule to the sample Event Manager application. He walks through the importance of the PrintDocument class and its members. He also shows how to handle printing the visual tree and how the ViewBox control can help. Module 6.2 – Multi Page Printing Ian Griffiths expands on his printing discussion by showing how to handle printing multiple pages of content for the sample Event Manager application. He shows how to paginate the content and points out various tips to keep in mind when determining the printable area. Module 7 – Running the Event Dashboard Out of Browser Click here to visit this module. This lab builds a dashboard for the sample application while explaining the fundamentals of the out of browser features, how to handle authentication, displaying notifications (toasts), and how to use native integration to use COM Interop with Silverlight. Link Download Source Download Lab Document Videos Module 7.1 – Out of Browser Ian Griffiths discusses the role of an Out of Browser application for administrators to manage the events and users in the sample Event Manager application. He discusses several reasons why out of browser applications may better suit your needs including custom chrome, toasts, window placement, cross domain access, and file access. He demonstrates the basic technique to take your application and make it work out of browser using the tools. Module 7.2 – NotificationWindow (Toasts) for Elevated Trust Out of Browser Applications Ian Griffiths discusses the how toasts can be used in the sample Event Manager application to show information that may require the user's attention. Ian covers how to create a toast using the NotificationWindow, security implications, and how to make the toast appear as needed. Module 7.3 – Out of Browser Window Placement Ian Griffiths discusses the how to manage the window positioning when building an out of browser application, handling the windows state, and controlling and handling activation of the window. Module 7.4 – Out of Browser Elevated Trust Application Overview Ian Griffiths discusses the implications of creating trusted out of browser application for the Event Manager sample application. He reviews why you might want to use elevated trust, what features is opens to you, and how to take advantage of them. Topics Ian covers include the dynamic keyword in C# 4, the AutomationFactory class, the API to check if you are in a trusted application, and communicating with Excel. Module 8 – Advanced Out of Browser and MEF Click here to visit this module. This hands-on lab walks through the creation of a trusted out of browser application and the new functionality that comes with that. You will learn to use COM Automation, handle the window closing event, set custom window chrome, digitally sign your Silverlight out of browser trusted application, create a silent install option, and take advantage of MEF. Link Download Source Download Lab Document Videos Module 8.1 – Custom Window Chrome for Elevated Trust Out of Browser Applications Ian Griffiths discusses how to replace the standard operating system window chrome with customized chrome for an elevated trusted out of browser application. He covers how it is important to handle close, resize, minimize, and maximize events. Ian mentions that the tooling was not ready when he shot this video, but the good news is that the tooling now supports setting the custom chrome directly from the property page for the Silverlight application. Module 8.2 – Window Closing Event for Out of Browser Applications Ian Griffiths discusses the WindowClosing event and how to handle and optionally cancel the event. Module 8.3 – Silent Install of Out of Browser Applications Ian Griffiths discusses how to use the SLLauncher executable to install an out of browser application. He discusses the optional command line switches that can be set including how the emulate switch can help you emulate the install process. Ian also shows how to setup a shortcut for the application and tell the application where it should look for future updates online. Module 8.4 – Digitally Signing Out of Browser Application Ian Griffiths discusses how and why to digitally sign an out of browser application using the signtool program. He covers what trusted certificates are, the implications of signing (or not signing), and the effect on the user experience. Module 8.5 – The Value of MEF with Silverlight Ian Griffiths discusses what MEF is, how your application can benefit from it, and the fundamental features it puts at your disposal. He covers the 3 step import, export and compose process as well as how to dynamically import XAP files using MEF. Summary As you can probably tell from the long list above – this series contains a ton of great content, and hopefully provides a nice end-to-end walkthrough that helps explain how to take advantage of Silverlight 4 (and all its new features).  Hope this helps, Scott

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  • What sources of sample work should be used in a job interview?

    - by Joan Venge
    One of my friends has been laid off. When I talked to him, he said they didn't let him take a copy of anything he worked on. When he asked how to show what he worked on to another employer in an interview, he was told that he will have some explaining to do. Should we, as programmers, be allowed to take samples of our previous work former employers? What sources of code should we be expected to show off in an interview? When almost every employer asks for sample work, how are we to justify what can be sent? Is it our responsibility to maintain after-work projects for our entire life so we have code we can legally show to our next employer?

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  • error 503: Can't deploy rails 3 app with apache + thin (bitnamy ruby stack)

    - by Pacu
    As you'll notice, I'm a bit of a noob on Rails. Here's the thing I have a EC2 Bitnami RubyStack AMI running. I'm trying to deploy the sample project to be sure I'm doing the right thing, but I'm not getting anywhere at all. I just get a 503 error I'm following bitnami's docs on thin + apache Here are my files: the httpd.conf I include in the main httpd.conf Alias /sample "/home/bitnami/stack/projects/sample/public" <Directory "/home/bitnami/stack/projects/sample/public"> AllowOverride None Order allow,deny Allow from all </Directory> ProxyPass /sample balancer://appcluster ProxyPassReverse /sample balancer://appcluster <Proxy balancer://appcluster> BalancerMember http://127.0.0.1:3001/sample BalancerMember http://127.0.0.1:3002/sample BalancerMember http://127.0.0.1:3003/sample BalancerMember http://127.0.0.1:3004/sample </Proxy> the thin.yml file chdir: /opt/bitnami/projects/sample environment: production address: 127.0.0.1 port: 3000 timeout: 30 log: log/thin.log pid: tmp/pids/thin.pid max_conns: 1024 max_persistent_conns: 512 require: [] wait: 30 servers: 5 prefix: /sample daemonize: true I'm able to start and stop apache, but thin does not stop correctly though. When I try to stop thin, I get this output /opt/bitnami/projects/sample$ sudo thin -C config/thin.yml stop Stopping server on 127.0.0.1:3000 ... Can't stop process, no PID found in tmp/pids/thin.3000.pid Stopping server on 127.0.0.1:3001 ... Can't stop process, no PID found in tmp/pids/thin.3001.pid Stopping server on 127.0.0.1:3002 ... Can't stop process, no PID found in tmp/pids/thin.3002.pid Stopping server on 127.0.0.1:3003 ... Can't stop process, no PID found in tmp/pids/thin.3003.pid Stopping server on 127.0.0.1:3004 ... Can't stop process, no PID found in tmp/pids/thin.3004.pid I've tried to use nginx as well, without any luck unfortunately. Thank you for your time and help!

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  • How do I generate a random curve for landscape (like Worms)? [closed]

    - by Stas
    Possible Duplicate: How do I generate terrain like that of Scorched Earth? How can I generate Worms-style terrain? I must build random curve line for the 2D Game on the BitMap (like in Worms, from the side). Teacher said that I should do it using Terrain Generation through recourcy (I work in Delphi 7). I understand the main principle, but I don't know how to introduce it as code. All measurements according to the screen resolution.

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  • How would i down-sample a .wav file then reconstruct it using nyquist? - in matlab [closed]

    - by martin
    This is all done in MatLab 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the various sampling at different frequencies?

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  • Help to bypass password for sample projects of excel.

    - by Munna
    Hello Friend.. I am doing project in EXCEL VBA. i am taking refernce of some projects made in excel vba. But when I trid to open that excel sample projects, it ask me for password. so how can bypass password for that excel project so i can take refrence so that i can take refrence of sample. Please help....

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  • How do I request a single random row from a force.com database in SOQL?

    - by Ollie C
    Total row-count is in the range 10k-100k rows. Can I use RAND() on force.com? Unfortunately although all the rows have a unique numeric identifier, there are many gaps, and I'd often want to select a random row from a filtered subset anyway. I suspect there's no particularly efficient way to do this, but is it possible at all? Ultimately all I want to do is to extract one row from a table (or a subset based on specific filter criteria) at random. If force.com doesn't let me select a random row, then can I query the rows to select from, and assign sequential IDs to all the rows, say 1-1,035, and then select a random number in that range locally, say 349, and then get row 349?

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  • How to select random image of specific size using Django / Python?

    - by Jonathan
    I've been using this little snippet to select random images. However I would like to change it to select only images of a certain size. I'm running into trouble checking against image size. If I use get_image_dimensions() I need to use a conditional statement, which then requires that I allow exceptions. So, I guess I need some pointers on just limiting by image dimensions. Thanks. import os import random import posixpath from django import template from django.conf import settings register = template.Library() def is_image_file(filename): """Does `filename` appear to be an image file?""" img_types = [".jpg", ".jpeg", ".png", ".gif"] ext = os.path.splitext(filename)[1] return ext in img_types @register.simple_tag def random_image(path): """ Select a random image file from the provided directory and return its href. `path` should be relative to MEDIA_ROOT. Usage: <img src='{% random_image "images/whatever/" %}'> """ fullpath = os.path.join(settings.MEDIA_ROOT, path) filenames = [f for f in os.listdir(fullpath) if is_image_file(f)] pick = random.choice(filenames) return posixpath.join(settings.MEDIA_URL, path, pick)

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  • What to do with random pages after a 301 redirect?

    - by Alex
    Hello, I did a standard 301 redirect for a domain, but the original domain has about 300 pages that have some strength. It doesn't make sense to make them all point back to the new home page because the individual pages are about some topics. Also, there aren't the same pages in the new domain, so where should the original random pages redirect to? I would like to have them rank for the same topics they used to, but without having the original domain giving them strength, they will just stop ranking and die off. What should I do? Thanks, Alex

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  • Is "watermarking" code with random trailing whitespace a good way to detect plagiarism?

    - by paperjam
    Consider this: int f(int x) { return 2 * x * x; } and this int squareAndDouble(int y) { return 2*y*y; } If you found these in independent bodies of code, you might give the two programmers the benefit of the doubt and assume they came up with more-or-less the same function independently. But look at the whitespace at the end of each line of code. Same pattern in both. Surely evidence of copying. On a larger piece of code, correlation of random whitespace at line ends would be irrefutable evidence of a shared origin. Now aside from the obvious weaknesses: e.g. visible or obvious in some editors, easily removed, I was wondering if it was worth deploying something like this in my open source project. My industry has a history of companies ripping off open source projects.

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  • How to make comment reply query in MYSQL?

    - by Prashant
    I am having comment reply (only till one level) functionality. All comments can have as many as replies but no replies can have their further replies. So my database table structure is like below Id ParentId Comment 1 0 this is come sample comment text 2 0 this is come sample comment text 3 0 this is come sample comment text 4 1 this is come sample comment text 5 0 this is come sample comment text 6 3 this is come sample comment text 7 1 this is come sample comment text In the above structures, commentid, 1 (has 2 replies) and 3 (1 reply) has replies. So to fetch the comments and their replies, one simple method is first I fetch all the comments having ParentId as 0 and then by running a while loop fetch all the replies of that particular commentId. But that seems to be running hundreds of queries if I'll have around 200 comments on a particular record. So I want to make a query which will fetch Comments with their replies sequentially as following; Id ParentId Comment 1 0 this is come sample comment text 4 1 this is come sample comment text 7 1 this is come sample comment text 2 0 this is come sample comment text 3 0 this is come sample comment text 6 3 this is come sample comment text 5 0 this is come sample comment text I also have a comment date column in my comment table, if anyone wants to use this with comment query. So finally I want to fetch all the comments and their replies by using one single mysql query. Please tell me how I can do that? Thanks

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  • how do I paste text to a line by line text filter like awk, without having stdin echo to the screen?

    - by Barton Chittenden
    I have a text in an email on a windows box that looks something like this: 100 some random text 101 some more random text 102 lots of random text, all different 103 lots of random text, all the same I want to extract the numbers, i.e. the first word on each line. I've got a terminal running bash open on my Linux box... If these were in a text file, I would do this: awk '{print $1}' mytextfile.txt I would like to paste these in, and get my numbers out, without creating a temp file. my naive first attempt looked like this: $ awk '{print $1}' 100 some random text 100 101 some more random text 101 102 lots of random text, all different 103 lots of random text, all the same 102 103 The buffering of stdin and stdout make a hash of this. I wouldn't mind if stdin all printed first, followed by all of stdout; this is what would happen if I were to paste into 'sort' for example, but awk and sed are a different story. a little more thought gave me this: open two terminals. Create a fifo file. Read from the fifo on one terminal, write to it on another. This does in fact work, but I'm lazy. I don't want to open a second terminal. Is there a way in the shell that I can hide the text echoed to the screen when I'm passing it in to a pipe, so that I paste this: 100 some random text 101 some more random text 102 lots of random text, all different 103 lots of random text, all the same but see this? $ awk '{print $1}' 100 101 102 103

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  • How can I log when reads to /dev/random block?

    - by ldrg
    I've noticed that since updating my server to Debian Squeeze the amount of entropy as reported by /proc/sys/kernel/random/entropy_avail is much lower than it was before the upgrade. I would like to know if this lower pool size is big enough to function with or if I need to look into getting more entropy sources. I think having a way to log blocking reads of /dev/random would show whether I have enough entropy or not.

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  • 2D Collision in Canvas - Balls Overlapping When Velocity is High

    - by kushsolitary
    I am doing a simple experiment in canvas using Javascript in which some balls will be thrown on the screen with some initial velocity and then they will bounce on colliding with each other or with the walls. I managed to do the collision with walls perfectly but now the problem is with the collision with other balls. I am using the following code for it: //Check collision between two bodies function collides(b1, b2) { //Find the distance between their mid-points var dx = b1.x - b2.x, dy = b1.y - b2.y, dist = Math.round(Math.sqrt(dx*dx + dy*dy)); //Check if it is a collision if(dist <= (b1.r + b2.r)) { //Calculate the angles var angle = Math.atan2(dy, dx), sin = Math.sin(angle), cos = Math.cos(angle); //Calculate the old velocity components var v1x = b1.vx * cos, v2x = b2.vx * cos, v1y = b1.vy * sin, v2y = b2.vy * sin; //Calculate the new velocity components var vel1x = ((b1.m - b2.m) / (b1.m + b2.m)) * v1x + (2 * b2.m / (b1.m + b2.m)) * v2x, vel2x = (2 * b1.m / (b1.m + b2.m)) * v1x + ((b2.m - b1.m) / (b2.m + b1.m)) * v2x, vel1y = v1y, vel2y = v2y; //Set the new velocities b1.vx = vel1x; b2.vx = vel2x; b1.vy = vel1y; b2.vy = vel2y; } } You can see the experiment here. The problem is, some balls overlap each other and stick together while some of them rebound perfectly. I don't know what is causing this issue. Here's my balls object if that matters: function Ball() { //Random Positions this.x = 50 + Math.random() * W; this.y = 50 + Math.random() * H; //Random radii this.r = 15 + Math.random() * 30; this.m = this.r; //Random velocity components this.vx = 1 + Math.random() * 4; this.vy = 1 + Math.random() * 4; //Random shade of grey color this.c = Math.round(Math.random() * 200); this.draw = function() { ctx.beginPath(); ctx.fillStyle = "rgb(" + this.c + ", " + this.c + ", " + this.c + ")"; ctx.arc(this.x, this.y, this.r, 0, Math.PI*2, false); ctx.fill(); ctx.closePath(); } }

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  • Spring security request matcher is not working with regex

    - by Felipe Cardoso Martins
    Using Spring MVC + Security I have a business requirement that the users from SEC (Security team) has full access to the application and FRAUD (Anti-fraud team) has only access to the pages that URL not contains the words "block" or "update" with case insensitive. Bellow, all spring dependencies: $ mvn dependency:tree | grep spring [INFO] +- org.springframework:spring-webmvc:jar:3.1.2.RELEASE:compile [INFO] | +- org.springframework:spring-asm:jar:3.1.2.RELEASE:compile [INFO] | +- org.springframework:spring-beans:jar:3.1.2.RELEASE:compile [INFO] | +- org.springframework:spring-context:jar:3.1.2.RELEASE:compile [INFO] | +- org.springframework:spring-context-support:jar:3.1.2.RELEASE:compile [INFO] | \- org.springframework:spring-expression:jar:3.1.2.RELEASE:compile [INFO] +- org.springframework:spring-core:jar:3.1.2.RELEASE:compile [INFO] +- org.springframework:spring-web:jar:3.1.2.RELEASE:compile [INFO] +- org.springframework.security:spring-security-core:jar:3.1.2.RELEASE:compile [INFO] | \- org.springframework:spring-aop:jar:3.0.7.RELEASE:compile [INFO] +- org.springframework.security:spring-security-web:jar:3.1.2.RELEASE:compile [INFO] | +- org.springframework:spring-jdbc:jar:3.0.7.RELEASE:compile [INFO] | \- org.springframework:spring-tx:jar:3.0.7.RELEASE:compile [INFO] +- org.springframework.security:spring-security-config:jar:3.1.2.RELEASE:compile [INFO] +- org.springframework.security:spring-security-acl:jar:3.1.2.RELEASE:compile Bellow, some examples of mapped URL path from spring log: Mapped URL path [/index] onto handler 'homeController' Mapped URL path [/index.*] onto handler 'homeController' Mapped URL path [/index/] onto handler 'homeController' Mapped URL path [/cellphone/block] onto handler 'cellphoneController' Mapped URL path [/cellphone/block.*] onto handler 'cellphoneController' Mapped URL path [/cellphone/block/] onto handler 'cellphoneController' Mapped URL path [/cellphone/confirmBlock] onto handler 'cellphoneController' Mapped URL path [/cellphone/confirmBlock.*] onto handler 'cellphoneController' Mapped URL path [/cellphone/confirmBlock/] onto handler 'cellphoneController' Mapped URL path [/user/update] onto handler 'userController' Mapped URL path [/user/update.*] onto handler 'userController' Mapped URL path [/user/update/] onto handler 'userController' Mapped URL path [/user/index] onto handler 'userController' Mapped URL path [/user/index.*] onto handler 'userController' Mapped URL path [/user/index/] onto handler 'userController' Mapped URL path [/search] onto handler 'searchController' Mapped URL path [/search.*] onto handler 'searchController' Mapped URL path [/search/] onto handler 'searchController' Mapped URL path [/doSearch] onto handler 'searchController' Mapped URL path [/doSearch.*] onto handler 'searchController' Mapped URL path [/doSearch/] onto handler 'searchController' Bellow, a test of the regular expressions used in spring-security.xml (I'm not a regex speciality, improvements are welcome =]): import java.util.Arrays; import java.util.List; public class RegexTest { public static void main(String[] args) { List<String> pathSamples = Arrays.asList( "/index", "/index.*", "/index/", "/cellphone/block", "/cellphone/block.*", "/cellphone/block/", "/cellphone/confirmBlock", "/cellphone/confirmBlock.*", "/cellphone/confirmBlock/", "/user/update", "/user/update.*", "/user/update/", "/user/index", "/user/index.*", "/user/index/", "/search", "/search.*", "/search/", "/doSearch", "/doSearch.*", "/doSearch/"); for (String pathSample : pathSamples) { System.out.println("Path sample: " + pathSample + " - SEC: " + pathSample.matches("^.*$") + " | FRAUD: " + pathSample.matches("^(?!.*(?i)(block|update)).*$")); } } } Bellow, the console result of Java class above: Path sample: /index - SEC: true | FRAUD: true Path sample: /index.* - SEC: true | FRAUD: true Path sample: /index/ - SEC: true | FRAUD: true Path sample: /cellphone/block - SEC: true | FRAUD: false Path sample: /cellphone/block.* - SEC: true | FRAUD: false Path sample: /cellphone/block/ - SEC: true | FRAUD: false Path sample: /cellphone/confirmBlock - SEC: true | FRAUD: false Path sample: /cellphone/confirmBlock.* - SEC: true | FRAUD: false Path sample: /cellphone/confirmBlock/ - SEC: true | FRAUD: false Path sample: /user/update - SEC: true | FRAUD: false Path sample: /user/update.* - SEC: true | FRAUD: false Path sample: /user/update/ - SEC: true | FRAUD: false Path sample: /user/index - SEC: true | FRAUD: true Path sample: /user/index.* - SEC: true | FRAUD: true Path sample: /user/index/ - SEC: true | FRAUD: true Path sample: /search - SEC: true | FRAUD: true Path sample: /search.* - SEC: true | FRAUD: true Path sample: /search/ - SEC: true | FRAUD: true Path sample: /doSearch - SEC: true | FRAUD: true Path sample: /doSearch.* - SEC: true | FRAUD: true Path sample: /doSearch/ - SEC: true | FRAUD: true Tests Scenario 1 Bellow, the important part of spring-security.xml: <security:http entry-point-ref="entryPoint" request-matcher="regex"> <security:intercept-url pattern="^.*$" access="ROLE_SEC" /> <security:intercept-url pattern="^(?!.*(?i)(block|update)).*$" access="ROLE_FRAUD" /> <security:access-denied-handler error-page="/access-denied.html" /> <security:form-login always-use-default-target="false" login-processing-url="/doLogin.html" authentication-failure-handler-ref="authFailHandler" authentication-success-handler-ref="authSuccessHandler" /> <security:logout logout-url="/logout.html" success-handler-ref="logoutSuccessHandler" /> </security:http> Behaviour: FRAUD group **can't" access any page SEC group works fine Scenario 2 NOTE that I only changed the order of intercept-url in spring-security.xml bellow: <security:http entry-point-ref="entryPoint" request-matcher="regex"> <security:intercept-url pattern="^(?!.*(?i)(block|update)).*$" access="ROLE_FRAUD" /> <security:intercept-url pattern="^.*$" access="ROLE_SEC" /> <security:access-denied-handler error-page="/access-denied.html" /> <security:form-login always-use-default-target="false" login-processing-url="/doLogin.html" authentication-failure-handler-ref="authFailHandler" authentication-success-handler-ref="authSuccessHandler" /> <security:logout logout-url="/logout.html" success-handler-ref="logoutSuccessHandler" /> </security:http> Behaviour: SEC group **can't" access any page FRAUD group works fine Conclusion I did something wrong or spring-security have a bug. The problem already was solved in a very bad way, but I need to fix it quickly. Anyone knows some tricks to debug better it without open the frameworks code? Cheers, Felipe

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  • Problems Allocating Objects of Derived Class Where Base Class has Abstract Virtual Functions

    - by user1743901
    I am trying to get this Zombie/Human agent based simulation running, but I am having problems with these derived classes (Human and Zombie) who have parent class "Creature". I have 3 virtual functions declared in "Creature" and all three of these are re-declared AND DEFINED in both "Human" and "Zombie". But for some reason when I have my program call "new" to allocate memory for objects of type Human or Zombie, it complains about the virtual functions being abstract. Here's the code: definitions.h #ifndef definitions_h #define definitions_h class Creature; class Item; class Coords; class Grid { public: Creature*** cboard; Item*** iboard; int WIDTH; int HEIGHT; Grid(int WIDTHVALUE, int HEIGHTVALUE); void FillGrid(); //initializes grid object with humans and zombies void Refresh(); //calls Creature::Die(),Move(),Attack(),Breed() on every square void UpdateBuffer(char** buffer); bool isEmpty(int startx, int starty, int dir); char CreatureType(int xcoord, int ycoord); char CreatureType(int startx, int starty, int dir); }; class Random { public: int* rptr; void Print(); Random(int MIN, int MAX, int LEN); ~Random(); private: bool alreadyused(int checkthis, int len, int* rptr); bool isClean(); int len; }; class Coords { public: int x; int y; int MaxX; int MaxY; Coords() {x=0; y=0; MaxX=0; MaxY=0;} Coords(int X, int Y, int WIDTH, int HEIGHT) {x=X; y=Y; MaxX=WIDTH; MaxY=HEIGHT; } void MoveRight(); void MoveLeft(); void MoveUp(); void MoveDown(); void MoveUpRight(); void MoveUpLeft(); void MoveDownRight(); void MoveDownLeft(); void MoveDir(int dir); void setx(int X) {x=X;} void sety(int Y) {y=Y;} }; class Creature { public: bool alive; Coords Location; char displayletter; Creature() {Location.x=0; Location.y=0;} Creature(int i, int j) {Location.setx(i); Location.sety(j);} virtual void Attack() =0; virtual void AttackCreature(Grid G, int attackdirection) =0; virtual void Breed() =0; void Die(); void Move(Grid G); int DecideSquare(Grid G); void MoveTo(Grid G, int dir); }; class Human : public Creature { public: bool armed; //if armed, chances of winning fight increased for next fight bool vaccinated; //if vaccinated, no chance of getting infected int bitecount; //if a human is bitten, bite count is set to a random number int breedcount; //if a human goes x steps without combat, will breed if next to a human int starvecount; //if a human does not eat in x steps, will die Human() {displayletter='H';} Human(int i, int j) {displayletter='H';} void Attack(Grid G); void AttackCreature(Grid G, int attackdirection); void Breed(Grid G); //will breed after x steps and next to human int DecideAttack(Grid G); }; class Zombie : public Creature { public: Zombie() {displayletter='Z';} Zombie(int i, int j) {displayletter='Z';} void Attack(Grid G); void AttackCreature(Grid G, int attackdirection); void Breed() {} //does nothing int DecideAttack(Grid G); void AttackCreature(Grid G, int attackdirection); }; class Item { }; #endif definitions.cpp #include <cstdlib> #include "definitions.h" Random::Random(int MIN, int MAX, int LEN) //constructor { len=LEN; rptr=new int[LEN]; //allocate array of given length for (int i=0; i<LEN; i++) { int random; do { random = rand() % (MAX-MIN+1) + MIN; } while (alreadyused(random,LEN,rptr)); rptr[i]=random; } } bool Random::alreadyused(int checkthis, int len, int* rptr) { for (int i=0; i<len; i++) { if (rptr[i]==checkthis) return 1; } return 0; } Random::~Random() { delete rptr; } Grid::Grid(int WIDTHVALUE, int HEIGHTVALUE) { WIDTH = WIDTHVALUE; HEIGHT = HEIGHTVALUE; //builds 2d array of creature pointers cboard = new Creature**[WIDTH]; for(int i=0; i<WIDTH; i++) { cboard[i] = new Creature*[HEIGHT]; } //builds 2d array of item pointers iboard = new Item**[WIDTH]; for (int i=0; i<WIDTH; i++) { iboard[i] = new Item*[HEIGHT]; } } void Grid::FillGrid() { /* For each creature pointer in grid, randomly selects whether to initalize as zombie, human, or empty square. This methodology can be changed to initialize different creature types with different probabilities */ int random; for (int i=0; i<WIDTH; i++) { for (int j=0; j<HEIGHT; j++) { Random X(1,100,1); //create a single random integer from [1,100] at X.rptr random=*(X.rptr); if (random < 20) cboard[i][j] = new Human(i,j); else if (random < 40) cboard[i][j] = new Zombie(i,j); else cboard[i][j] = NULL; } } //at this point every creature pointer should be pointing to either //a zombie, human, or NULL with varying probabilities } void Grid::UpdateBuffer(char** buffer) { for (int i=0; i<WIDTH; i++) { for (int j=0; j<HEIGHT; j++) { if (cboard[i][j]) buffer[i][j]=cboard[i][j]->displayletter; else buffer[i][j]=' '; } } } bool Grid::isEmpty(int startx, int starty, int dir) { Coords StartLocation(startx,starty,WIDTH,HEIGHT); switch(dir) { case 1: StartLocation.MoveUp(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 2: StartLocation.MoveUpRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 3: StartLocation.MoveRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 4: StartLocation.MoveDownRight(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 5: StartLocation.MoveDown(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 6: StartLocation.MoveDownLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 7: StartLocation.MoveLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; case 8: StartLocation.MoveUpLeft(); if (cboard[StartLocation.x][StartLocation.y]) return 0; } return 1; } char Grid::CreatureType(int xcoord, int ycoord) { if (cboard[xcoord][ycoord]) //if there is a creature at location xcoord,ycoord return (cboard[xcoord][ycoord]->displayletter); else //if pointer at location xcoord,ycoord is null, return null char return '\0'; } char Grid::CreatureType(int startx, int starty, int dir) { Coords StartLocation(startx,starty,WIDTH,HEIGHT); switch(dir) { case 1: StartLocation.MoveUp(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 2: StartLocation.MoveUpRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 3: StartLocation.MoveRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 4: StartLocation.MoveDownRight(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 5: StartLocation.MoveDown(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 6: StartLocation.MoveDownLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 7: StartLocation.MoveLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); case 8: StartLocation.MoveUpLeft(); if (cboard[StartLocation.x][StartLocation.y]) return (cboard[StartLocation.x][StartLocation.y]->displayletter); } //if function hasn't returned by now, square being looked at is pointer to null return '\0'; //return null char } void Coords::MoveRight() {(x==MaxX)? (x=0):(x++);} void Coords::MoveLeft() {(x==0)? (x=MaxX):(x--);} void Coords::MoveUp() {(y==0)? (y=MaxY):(y--);} void Coords::MoveDown() {(y==MaxY)? (y=0):(y++);} void Coords::MoveUpRight() {MoveUp(); MoveRight();} void Coords::MoveUpLeft() {MoveUp(); MoveLeft();} void Coords::MoveDownRight() {MoveDown(); MoveRight();} void Coords::MoveDownLeft() {MoveDown(); MoveLeft();} void Coords::MoveDir(int dir) { switch(dir) { case 1: MoveUp(); break; case 2: MoveUpRight(); break; case 3: MoveRight(); break; case 4: MoveDownRight(); break; case 5: MoveDown(); break; case 6: MoveDownLeft(); break; case 7: MoveLeft(); break; case 8: MoveUpLeft(); break; case 0: break; } } void Creature::Move(Grid G) { int movedir=DecideSquare(G); MoveTo(G,movedir); } int Creature::DecideSquare(Grid G) { Random X(1,8,8); //X.rptr now points to 8 unique random integers from [1,8] for (int i=0; i<8; i++) { int dir=X.rptr[i]; if (G.isEmpty(Location.x,Location.y,dir)) return dir; } return 0; } void Creature::MoveTo(Grid G, int dir) { Coords OldLocation=Location; Location.MoveDir(dir); G.cboard[Location.x][Location.y]=this; //point new location to this creature G.cboard[OldLocation.x][OldLocation.y]=NULL; //point old location to NULL } void Creature::Die() { if (!alive) { delete this; this=NULL; } } void Human::Breed(Grid G) { if (!breedcount) { Coords BreedLocation=Location; Random X(1,8,8); for (int i=0; i<8; i++) { BreedLocation.MoveDir(X.rptr[i]); if (!G.cboard[BreedLocation.x][BreedLocation.y]) { G.cboard[BreedLocation.x][BreedLocation.y])=new Human(BreedLocation.x,BreedLocation.y); return; } } } } int Human::DecideAttack(Grid G) { Coords AttackLocation=Location; Random X(1,8,8); int attackdir; for (int i=0; i<8; i++) { attackdir=X.rptr[i]; switch(G.CreatureType(Location.x,Location.y,attackdir)) { case 'H': break; case 'Z': return attackdir; case '\0': break; default: break; } } return 0; //no zombies! } int AttackRoll(int para1, int para2) { //outcome 1: Zombie wins, human dies //outcome 2: Human wins, zombie dies //outcome 3: Human wins, zombie dies, but human is bitten Random X(1,100,1); int roll= *(X.rptr); if (roll < para1) return 1; else if (roll < para2) return 2; else return 3; } void Human::AttackCreature(Grid G, int attackdirection) { Coords AttackLocation=Location; AttackLocation.MoveDir(attackdirection); int para1=33; int para2=33; if (vaccinated) para2=101; //makes attackroll > para 2 impossible, never gets infected if (armed) para1-=16; //reduces chance of zombie winning fight int roll=AttackRoll(para1,para2); //outcome 1: Zombie wins, human dies //outcome 2: Human wins, zombie dies //outcome 3: Human wins, zombie dies, but human is bitten switch(roll) { case 1: alive=0; //human (this) dies return; case 2: G.cboard[AttackLocation.x][AttackLocation.y]->alive=0; return; //zombie dies case 3: G.cboard[AttackLocation.x][AttackLocation.y]->alive=0; //zombie dies Random X(3,7,1); //human is bitten bitecount=*(X.rptr); return; } } int Zombie::DecideAttack(Grid G) { Coords AttackLocation=Location; Random X(1,8,8); int attackdir; for (int i=0; i<8; i++) { attackdir=X.rptr[i]; switch(G.CreatureType(Location.x,Location.y,attackdir)) { case 'H': return attackdir; case 'Z': break; case '\0': break; default: break; } } return 0; //no zombies! } void Zombie::AttackCreature(Grid G, int attackdirection) { int reversedirection; if (attackdirection < 9 && attackdirection>0) { (attackdirection<5)? (reversedirection=attackdirection+4):(reversedirection=attackdirection-4); } else reversedirection=0; //this should never happen //when a zombie attacks a human, the Human::AttackZombie() function is called //in the "reverse" direction, utilizing that function that has already been written Coords ZombieLocation=Location; Coords HumanLocation=Location; HumanLocation.MoveDir(attackdirection); if (G.cboard[HumanLocation.x][HumanLocation.y]) //if there is a human there, which there should be G.cboard[HumanLocation.x][HumanLocation.y]->AttackCreature(G,reversedirection); } void Zombie::Attack(Grid G) { int attackdirection=DecideAttack(G); AttackCreature(G,attackdirection); } main.cpp #include <cstdlib> #include <iostream> #include "definitions.h" using namespace std; int main(int argc, char *argv[]) { Grid G(500,500); system("PAUSE"); return EXIT_SUCCESS; }

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