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• iOS and Server: OAuth strategy

  - by drekka

  I'm trying to working how to handle authentication when I have iOS clients accessing a Node.js server and want to use services such as Google, Facebook etc to provide basic authentication for my application. My current idea of a typical flow is this: User taps a Facebook/Google button which triggers the OAuth(2) dialogs and authenticates the user on the device. At this point the device has the users access token. This token is saved so that the next time the user uses the app it can be retrieved. The access token is transmitted to my Node.js server which stores it, and tags it as un-verified. The server verifies the token by making a call to Facebook/google for the users email address. If this works the token is flagged as verified and the server knows it has a verified user. If Facebook/google fail to authenticate the token, the server tells iOS client to re-authenticate and present a new token. The iOS client can now access api calls on my Node.js server passing the token each time. As long as the token matches the stored and verified token, the server accepts the call. Obviously the tokens have time limits. I suspect it's possible, but highly unlikely that someone could sniff an access token and attempt to use it within it's lifespan, but other than that I'm hoping this is a reasonably secure method for verification of users on iOS clients without having to roll my own security. Any opinions and advice welcome.

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• We're Subversion Geeks and we want to know the benefits of Mercurial

  - by Matt

  Having read I'm a Subversion geek, why should I consider or not consider Mercurial or Git or any other DVCS. I have a related follow up question. I read that question and read the recommended links and videos and I see the benefits but I don't see the overall mindshift people are talking about. Our team is of 8-10 developers that work on one large code base consisting of 60 projects. We use Subversion and have a main trunk. When a developer starts a new Fogbugz case they create a svn branch, do the work on the branch and when they're done they merge back to the trunk. Occasionally they may stay on the branch for an extended time and merge the trunk to the branch to pick up the changes. When I watched Linus talk about people creating a branch and never doing it again, that's not us at all. We create probably 50-100 branches a week without issue. The biggest challenge is the merging but we've gotten pretty good at that as well. I tend to merge by fogbugz case & checkin rather than the entire root of the branch. We never work remotely and we never make branches off of branches. If you're the only one working in that section of the code base then the merge to the trunk goes smoothly. If someone else had modified the same section of code then the merge can get messy and you might need to do some surgery. Conflicts are conflicts, I don't see how any system could get it right most of the time unless if was smart enough to understand the code. After creating a branch the following checkout of 60k+ files takes some time but that would be an issue with any source control system we'd use. Is there some benefit of any DVCS that we're not seeing that would be of great help to us?

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• Twisted: why is it that passing a deferred callback to a deferred thread makes the thread blocking a

  - by surtyaarthoughts

  I unsuccessfully tried using txredis (the non blocking twisted api for redis) for a persisting message queue I'm trying to set up with a scrapy project I am working on. I found that although the client was not blocking, it became much slower than it could have been because what should have been one event in the reactor loop was split up into thousands of steps. So instead, I tried making use of redis-py (the regular blocking twisted api) and wrapping the call in a deferred thread. It works great, however I want to perform an inner deferred when I make a call to redis as I would like to set up connection pooling in attempts to speed things up further. Below is my interpretation of some sample code taken from the twisted docs for a deferred thread to illustrate my use case: #!/usr/bin/env python from twisted.internet import reactor,threads from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(): print 'doing lookup... this may take a while' time.sleep(10) return 'results from redis' def result(res): print res def main(): lc = LoopingCall(main_loop) lc.start(2) d = threads.deferToThread(aBlockingRedisCall) d.addCallback(result) reactor.run() if __name__=='__main__': main() And here is my alteration for connection pooling that makes the code in the deferred thread blocking : #!/usr/bin/env python from twisted.internet import reactor,defer from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(x): if x<5: #all connections are busy, try later print '%s is less than 5, get a redis client later' % x x+=1 d = defer.Deferred() d.addCallback(aBlockingRedisCall) reactor.callLater(1.0,d.callback,x) return d else: print 'got a redis client; doing lookup.. this may take a while' time.sleep(10) # this is now blocking.. any ideas? d = defer.Deferred() d.addCallback(gotFinalResult) d.callback(x) return d def gotFinalResult(x): return 'final result is %s' % x def result(res): print res def aBlockingMethod(): print 'going to sleep...' time.sleep(10) print 'woke up' def main(): lc = LoopingCall(main_loop) lc.start(2) d = defer.Deferred() d.addCallback(aBlockingRedisCall) d.addCallback(result) reactor.callInThread(d.callback, 1) reactor.run() if __name__=='__main__': main() So my question is, does anyone know why my alteration causes the deferred thread to be blocking and/or can anyone suggest a better solution?

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• How often does Dreamhost change IP Addresses

  - by pjreddie

  So I just migrated our site to dreamhost because they are free for non-profits. However, right after I switched the nameservers over to them they changed the IP address of the site. So first they propagated out IP address x.x.x.180, then they switched it to x.x.x.178 and had to propagate that out. Point being it meant a lot of downtime since a lot of big DNS servers (like google) thought the address was still x.x.x.180 for up to 5 hours after they switched it. This is compounded by the fact that most our visitors to the site live here in Unalaska and we have local DNS servers that take a LONG time to update (like a day or more) since we get all our internet over satellite. So every time Dreamhost changes our IP address it can mean a day of downtime for us in our community. So my question is, how often do these changes take place? I asked Dreamhost support and they gave me a vague response: I wish I could say, however those changes happen at random times. They're not that frequent, maybe even months between updates, but there's no way to know for sure. First, I hardly believe that they don't know their own system well enough to give me at least some estimate or average. Second, is it worth looking at other providers so that I can get a static IP address? We were hosting the site here originally and hadn't run into this problem since we have a static IP here. We don't get a ton of traffic but usually around 500 hits a day or so, sometimes more if our stories are featured on statewide or national news broadcasts. So hours of downtime every time Dreamhost "randomly" decides to move our server location can be bad for our readership.

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• Is there any site which tells or highlights by zone developer income source? I think i am getting less yearly [closed]

  - by YumYumYum

  http://www.itjobswatch.co.uk/ Thats the only one good site i have found, but missing for Belgium and for other European countries. I was searching a site which can tell the income source details for European developer (specially for Belgium). But mostly not a single website exist who tells the true. My situation: As a programmer myself in one company i use all my knowledge, 20++ hours a day (office , home, office, home) because every-time its challenge/complex/stress/over-time feature-requests, at the end of the year in Europe i was getting in total not even the lowest amount shown here (UK pound vs Euro + high-tech most of the time they use + speed in development): http://www.itjobswatch.co.uk/ In one company i have to use my best performance knowledge for whole year with: C, Java, PHP (Zend Framework, Cakephp), BASH, MySQL/DB2, Linux/Unix, Javascript, Dojo, JQuery, Css, Html, Xml. Company wants to pay lesser but always it has to be perfect and it has to be solid gold and diamond like quality. And the total amount in Europe is not sufficient for me if i compare with other countries and living cost in Europe including taxes. Is there any developers/community site where we can see by country, zone what is minimum to maximum income source getting offered to the developers? So that some developers who is in troubles, they can shout and speak up louder with those references?

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• Arguments for moving from LINQtoSQL to Nhibernate?

  - by sah302

  Backstory: Hi all, I just spent a lot of time reading many of the LINQ vs Nhibernate threads here and on other sites. I work in a small development team of 4 people and we don't even have really any super experienced developers. We work for a small company that has a lot of technical needs but not enough developers to implement them (and hiring more is out of the question right now). Typically our projects (which individually are fairly small) have been coded separately and weren't really layered in anyway, code wasn't re-used, no class libraries, and we just use the LINQtoSQL .dbml files for our pojects, we really don't even use objects but pass around values and stuff, the only time we use objects is when inserting to a database (heck not even querying since you don't need to assign it to a type and can just bind to gridview). Despite all this as I said our company has a lot of technical needs, no one could come to us for a year and we would have plenty of work to implement requested features. Well I have decided to change that a bit first by creating class libraries and actually adding layers to our applications. I am trying to meet these guys halfway by still using LINQtoSQL as the ORM yet and still use VB as the language. However I am finding it a b***h of a time dealing with so many thing in LINQtoSQL that I found easy in Nhibernate (automatic handling of the session, criteria creation easier than expression trees, generic an dynamic querying easier etc.) So... Question: How can I convince my lead developers and other senior programmers that switching to Nhibernate is a good thing? That being in control of our domain objects is a good thing? That being able to implement interfaces is a good? I've tried exlpaining the advantages of this before but it's not understood by them because they've never programmed in a true OO & layered way. Also one of the counter arguments to this I can see is sqlMetal generates those classes automatically and therefore it saves a lot of time. I can't really counter that other than saying spending more time on infrastructure to make it more scalable and flexible is good, but they can't see how. Again, I know the features and advantages (somewhat enough I believe) of each, but I need arguments applicable to my context, hence why I provided the context. I just am not a very good arguer I guess. (Caveat: For all the LINQtoSQL lovers, I may just not be super proficient as LINQ, but I find it very cumbersome that you are required to download some extra library for dynamic queries which don't by default support guid comparisons, and I also find the way of updating entitites to be cumbersome as well in terms of data context managing, so it could just be that I suck hehe.)

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• Friday Fun: Abduction

  - by Mysticgeek

  Finally another Friday has arrived and it’s time to waste the afternoon on company time playing a flash game. Today we take a look at a fun game called Abduction. Abduction Abduction is a neat game where you snatch people and livestock to sell them on the intergalactic market.   The controls are basic using the arrow keys or W,A,S,D and the left mouse button. Here is the tutorial that you can play first to get the hang of it. While you’re abducting hillbillies, they throw pitch forks and other objects at your craft so you need to avoid them.   The game has several levels to keep you distracted until quitting time. Play Abduction at FreeWebArcade Similar Articles Productive Geek Tips Take Screenshots in Firefox the Easy WayFriday Fun: Portal, the Flash VersionFriday Fun: Play Bubble QuodFriday Fun: Gravitee 2Friday Fun: Compulse TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional How to Browse Privately in Firefox Kill Processes Quickly with Process Assassin Need to Come Up with a Good Name? Try Wordoid StockFox puts a Lightweight Stock Ticker in your Statusbar Explore Google Public Data Visually The Ultimate Excel Cheatsheet

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• Discuss: PLs are characterised by which (iso)morphisms are implemented

  - by Yttrill

  I am interested to hear discussion of the proposition summarised in the title. As we know programming language constructions admit a vast number of isomorphisms. In some languages in some places in the translation process some of these isomorphisms are implemented, whilst others require code to be written to implement them. For example, in my language Felix, the isomorphism between a type T and a tuple of one element of type T is implemented, meaning the two types are indistinguishable (identical). Similarly, a tuple of N values of the same type is not merely isomorphic to an array, it is an array: the isomorphism is implemented by the compiler. Many other isomorphisms are not implemented for example there is an isomorphism expressed by the following client code: match v with | ((?x,?y),?z = x,(y,z) // Felix match v with | (x,y), - x,(y,z) (* Ocaml *) As another example, a type constructor C of int in Felix may be used directly as a function, whilst in Ocaml you must write a wrapper: let c x = C x Another isomorphism Felix implements is the elimination of unit values, including those in tuples: Felix can do this because (most) polymorphic values are monomorphised which can be done because it is a whole program analyser, Ocaml, for example, cannot do this easily because it supports separate compilation. For the same reason Felix performs type-class dispatch at compile time whilst Haskell passes around dictionaries. There are some quite surprising issues here. For example an array is just a tuple, and tuples can be indexed at run time using a match and returning a value of a corresponding sum type. Indeed, to be correct the index used is in fact a case of unit sum with N summands, rather than an integer. Yet, in a real implementation, if the tuple is an array the index is replaced by an integer with a range check, and the result type is replaced by the common argument type of all the constructors: two isomorphisms are involved here, but they're implemented partly in the compiler translation and partly at run time.

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• XNA C# How to draw fonts in different color

  - by XNA newbie

  I'm doing a simple chat system with XNA C#. It is a chatbox that contains 5 lines of chat typed by the users. Something like a MMORPG chatting system. [User1name] says: Hi [User2name] says: Hello [User1name] says: What are you doing? [User2name] says: I'm fine [System] The time is now 1:03AM. When the user pressed 'ENTER', the text he entered will be added inside an ArrayList chatList.Add(s); For displaying the text he entered, I used for (int i = 0; i < chatList.Count(); i++) { spriteBatch.DrawString(font, chatList[i], new Vector2(40, arr1[i]), Color.Yellow); } *arr1[i] contains 5 y-axis points to print my 5 line of chats in the chatbox Question1: What if I have another type of message which will be added into ChatList (something like a system message). I need the System Message to be printed out in red color. And if the user keeps on chatting, the chat box will be updated according: (MAX 5 LINES) The newest chat will be shown below, and the oldest one will be deleted if they reached the max 5 lines. [User2name] says: Hello [User1name] says: What are you doing? [User2name] says: I'm fine [System] The time is now 1:03AM. [User1name] says: Ok, great to hear that! I'm having trouble to print each line color according to their msg type. For normal msg, it should be yellow. For system msg, it should be red. Question2: And for the next problem, I need the chat texts to be white color, while the names of the user is yellow (like warcraft3 chat system). How do I do that? I have a hard time thinking of a solution for these to work. Advise needed.

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• how to choose a web framework and javascript library?

  - by Trylks

  I've been procrastinating learning some framework for web apps w/ some library for AJAX, something like django with prototype, or turbogears with mootools, or zeta components with dojo, grok, jquery, symfony... The point is to spend some of my spare time, have "fun" and create cool stuff that hopefully is some useful. I think maybe I wouldn't like something like GWT or pyjamas because I wouldn't like to "get married" with some technology, I want to keep my freedom to add another javascript library, and so on. I didn't decide even the language yet, but I think I'd prefer python. PHP could be fine if there is some framework that is nice enough. Besides that, I don't even know where to start. I don't feel like learning a framework to then realize there is something that I cannot comfortably do, switch to another framework then find that a third framework has something really cool, etc. And the same goes for javascript libraries. So, some guidance would be really appreciated. I don't really know why are so many options available and what do they aim for, I guess some of them focus on some aspects and some on others, but I just want to make cool and nice apps that I can easily maintain, without spending too much time on coding or learning and avoiding the "trapped in the framework" feeling, when doing something is awfully complicated (or even impossible) with compared with the rest of things or doing that same thing on a different framework. I guess in the end I'll go for django and jquery since they are the most widely used options, afaik, but if I was going for the most widely used options I guess I should choose Java or PHP (I don't really like Java for my spare time, but php is not so bad), so I preferred to ask first. I think the question has to consider both, framework and library, since sometimes they are coupled. I think this is the place to ask this kind of things, sorry if not, and thank you.

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• Space-efficient data structures for broad-phase collision detection

  - by Marian Ivanov

  As far as I know, these are three types of data structures that can be used for collision detection broadphase: Unsorted arrays: Check every object againist every object - O(n^2) time; O(log n) space. It's so slow, it's useless if n isn't really small. for (i=1;i<objects;i++){ for(j=0;j<i;j++) narrowPhase(i,j); }; Sorted arrays: Sort the objects, so that you get O(n^(2-1/k)) for k dimensions O(n^1.5) for 2d and O(n^1.67) for 3d and O(n) space. Assuming the space is 2D and sortedArray is sorted so that if the object begins in sortedArray[i] and another object ends at sortedArray[i-1]; they don't collide Heaps of stacks: Divide the objects between a heap of stacks, so that you only have to check the bucket, its children and its parents - O(n log n) time, but O(n^2) space. This is probably the most frequently used approach. Is there a way of having O(n log n) time with less space? When is it more efficient to use sorted arrays over heaps and vice versa?

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• Karmetasploit (aircrack-ng) Not consistantly Broadcasting AP ssid

  - by Sparky

  I cannot seem to get karmetasploit to broadcast my AP. Actually, taking it back a few steps I cannot get airbase-ng (v.r2154) to broadcast an SSID. I have seen it broadcast a few intermittent times (not many at all), but most of the time it doesn't show up at all. When it showed up the last time it came up as ad-hoc also. simplest comand I have tried: sudo airbase-ng -e "Wifi-test" -c 11 -v mon0 (I have tried with/without -c and -P -C 30) It appears to work just fine on the attacking machine, but nothing gets broadcasted. I have tried viewing from (3) different computers (winXP, Win7, ubuntu 12.04) Additionally, I am running Ubuntu 12.04 I have tried (3) different wireless cards Internal Card: Intel 4965 External USB: Ubiquiti Atheros carl9170 external SUB: ALFA AWUS036H Realtek RTL8187L I have tried putting each in/out of monitor mode (airmon-ng start monX) I have also tested to see if injection is working: sudo aireplay-ng -9 mon0 sudo aireplay-ng -9 mon0 22:37:54 Trying broadcast probe requests... 22:37:55 Injection is working! 22:37:56 Found 4 APs ... ... Has anyone experienced this issue and have advice/solution? I the aircrack-ng forum site has been down for some time, so I cannot get advice from that site. Thanks, Sparky

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• Fixed-Function vs Shaders: Which for beginner?

  - by Rob Hays

  I'm currently going to college for computer science. Although I do plan on utilizing an existing engine at some point to create a small game, my aim right now is towards learning the fundamentals: namely, 3D programming. I've already done some research regarding the choice between DirectX and OpenGL, and the general sentiment that came out of that was that whether you choose OpenGL or DirectX as your training-wheels platform, a lot of the knowledge is transferrable to the other platform. Therefore, since OpenGL is supported by more systems (probably a silly reason to choose what to learn), I decided that I'm going to learn OpenGL first. After I made this decision to learn OpenGL, I did some more research and found out about a dichotomy that I was somewhere unaware of all this time: fixed-function OpenGL vs. modern programmable shader-based OpenGL. At first, I thought it was an obvious choice that I should choose to learn shader-based OpenGL since that's what's most commonly used in the industry today. However, I then stumbled upon the very popular Learning Modern 3D Graphics Programming by Jason L. McKesson, located here: http://www.arcsynthesis.org/gltut/ I read through the introductory bits, and in the "About This Book" section, the author states: "First, much of what is learned with this approach must be inevitably abandoned when the user encounters a graphics problem that must be solved with programmability. Programmability wipes out almost all of the fixed function pipeline, so the knowledge does not easily transfer." yet at the same time also makes the case that fixed-functionality provides an easier, more immediate learning curve for beginners by stating: "It is generally considered easiest to teach neophyte graphics programmers using the fixed function pipeline." Naturally, you can see why I might be conflicted about which paradigm to learn: Do I spend a lot of time learning (and then later unlearning) the ways of fixed-functionality, or do I choose to start out with shaders? My primary concern is that modern programmable shaders somehow require the programmer to already understand the fixed-function pipeline, but I doubt that's the case. TL;DR == As an aspiring game graphics programmer, is it in my best interest to learn 3D programming through fixed-functionality or modern shader-based programming?

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• PHP max_execution_time not timing out

  - by Joey Ezekiel

  This is not one of the regular questions if sleep is counted for timeout or stuff like that. Ok, here's the problem: I've set the max_execution_time for PHP as 15 seconds and ideally this should time out when it crosses the set limit, but it doesn't. Apache has been restarted after the change to the php.ini file and an ini_get('max_execution_time') is all fine. Sometimes the script runs for upto 200 seconds which is crazy. I have no database communication whatsoever. All the script does is looking for files on the unix filesystem and in some cases re-directing to another JSP page. There is no sleep() on the script. I calculate the total execution time of the PHP script like this: At the start of the script I set : $_mtime = microtime(); $_mtime = explode(" ",$_mtime); $_mtime = $_mtime[1] + $_mtime[0]; $_gStartTime = $_mtime; and the end time($_gEndTime) is calculated similarly. The total time is calculated in a shutdown function that I've registered: register_shutdown_function('shutdown'); ............. function shutdown() { .............. .............. $_total_time = $_gEndTime - $_gStartTime; .............. switch (connection_status ()) { case CONNECTION_NORMAL: .... break; .... case CONNECTION_TIMEOUT: .... break; ...... } } Note: I cannot use $_SERVER['REQUEST_TIME'] because my PHP version is incompatible. That sucks - I know. 1) Well, my first question obviously is is why is my PHP script executing even after the set timeout limit? 2) Apache has the Timeout directive which is 300 seconds but the PHP binary does not read the Apache config and this should not be a problem. 3) Is there a possibility that something is sending PHP into a sleep mode? 4) Am I calculating the execution time in a wrong way? Is there a better way to do this? I'm stumped at this point. PHP Wizards - please help.

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• Self Service Reporting With PowerPivot

  - by blakmk

  There are so many cool new features in Sql 2008 release 2 it was difficult for me to pick a topic for T-SQL Tuesday . But the one that I am now a secret fan of, I once resented for its creation. Let me explain, for years I have encountered reporting systems cobbled together in tools like Access and Excel built by "database hobbyists" who had no formal training in database design or best practices. They would take their monstrosities as far as they could go before ultimatley it stopped working or the person that wrote it left the company. At that point it would become the resident DBA's problem to support it as a Live application. So when I first heard of Power Pivot, a sense of Deja Vu overtook me and I felt like the guy in the Ausin Powers movie , knowing the inevitable is coming but somehow unsure how to get out of the way. But when I eventually saw it in action, I quickly realised that it is a very powerful tool. It has a much smaller "time to market" than traditional BI architectures. Combined with the new features of Excel, some pretty impressive dashboards can be produced.Of course PowerPivot is not a magic bullet and along with potential scalability issues there are the usual issues such as master data management and data quality that cannot be overcome easily with power pivot. As a tool though, it has potential. Traditional BI is expensive, both in terms of time and the amount of resources it takes to deliver the system. The time lag between an analyst or a commercial accountant requesting reports and the report being delivered can make a huge commercial difference. I have observed companies where empowered end users become extremely productive when allowed to plough in to various disperate datasets. It may not be the correct way or the most sustainable but its cheap and quick. In these times when budgets are being slashed and we are forced to deliver more with less, why not empower the end user in a tool that is designed for exactly this task.... @blakmk  

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• CheckMemoryAllocationGame Sample

  - by Michael B. McLaughlin

  Many times I’ve found myself wondering how much GC memory some operation allocates. This is primarily in the context of XNA games due to the desire to avoid generating garbage and thus triggering a GC collection. Many times I’ve written simple programs to check allocations. I did it again recently. It occurred to me that many XNA developers find themselves asking this question from time to time. So I cleaned up my sample and published it on my website. Feel free to download it and put it to use. It’s rather thoroughly commented. The location where you insert the code you wish to check is in the Update method found in Game1.cs. The default that I put in is a line of code that generates a new Guid using Guid.NewGuid (which, if you’re curious, does not create any heap allocations). Read all of the comments in the Update method (at the very least) to make sure that your code is measured properly. It’s important to make sure that you meaningfully reference any thing you create after the second call to get the memory or else (in Release configuration at least) you will likely get incorrect results. Anyway, it should make sense when you read the comments and if not, feel free to post a comment here or ask me on Twitter. You can find my utilities and code samples page here: http://www.bobtacoindustries.com/developers/utils/Default.aspx To download CheckMemoryAllocationGame’s source code directly: http://www.bobtacoindustries.com/developers/utils/CheckMemoryAllocationGame.zip (If you’re looking to do this outside of the context of an XNA game, the measurement code in the Update method can easily be adapted into, e.g., a C# Windows Console application. In the past I mostly did that, actually. But I didn’t feel like adding references to all the XNA assemblies this time and… anyway, if you want you can easily convert it to a console application. If there’s any demand for it, I’ll do it myself and update this post when I get a chance.)

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• How to mange big amount users at server side?

  - by Rami

  I built a social android application in which users can see other users around them by gps location. at the beginning thing went well as i had low number of users, But now that I have increasing number of users (about 1500 +100 every day) I revealed a major problem in my design. In my Google App Engine servlet I have static HashMap that holding all the users profiles objects, currenty 1500 and this number will increase as more users register. Why I'm doing it Every user that requesting for the users around him compares his gps with other users and check if they are in his 10km radius, this happens every 5 min on average. That is why I can't get the users from db every time because GAE read/write operation quota will tare me apart. The problem with this desgin is As the number of users increased the Hashmap turns to null every 4-6 hours, I thing that this time is getting shorten but I'm not sure. I'm fixing this by reloading the users from the db every time I detect that it became null, But this causes DOS to my users for 30 sec, So I'm looking for better solution. I'm guessing that it happens because the size of the hashmap, Am I right? I have been advised to use spatial database, but that mean that I can't work with GAE any more and that mean that I need to build my big server all over again and lose my existing DB. Is there something I can do with the existing tools? Thanks.

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• OpenGL profiling with AMD PerfStudio 2

  - by Aurus

  I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose FPS for nothing so I keep looking for more improvements. The first thing I noticed is the "huge" time where no calls are made before SwapBuffer (the black one). Well I know that OpenGL works asynchronous so SwapBuffer has to wait until everything is done. But shouldn't PerfStudio mark this time also as black ? Correct me If I am wrong. The second thing I noticed is that some glUniform2f calls just take longer (the brown ones). I mean they should all upload 2floats to the GPU how can the time be so different from call to call. The program isn't even changed or something like that. I also tried to look at other programs like gDebugger or CodeXL but they often crashed and they show less statistics (only # of calls or redundant calls etc.) EDIT: I also realized that the draw calls also have different durations, which was obvious for me but sometimes drawing more vertices is faster than drawing less vertices.

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• Can anyone recommend an AI sandbox?

  - by user19433

  I'm passionate person, who has been around AI from a long time [1] but never going in deep enough. Now it's time! I've been really looking for some way to concentrate on AI coding but couldn't succeeded to find an AI environment I can focus on. I just want to use an AI sandbox environment which would let me have tools like: visibility information character controller able to easily define a level, with obstacles of course physics collider management triggers management don't need to be a shiny, eye candy graphical render : this is about pathfinding, tactical reasoning, etc.. I have tried : Unreal Dev Kit : while the new release announce is about C++ coding, this is about external tools and will be released in 2013 Cry Engine : really interesting as AI is presents here but coding with it appears to be an hell: did I got it wrong ? Half Life source, C4, Torque, Dx Studio : either quite old, not very useful or costly these imply to dig in documentation (when provided) to code everything, graphics included. Unity 3D : the most promising platform. While you also need to create your own environment, there are lot of examples. The disadvantage is, in addition to spend time to have this env. working, is the languages choice : C#, Javascript or Boo. C# is not that hard, but this implies you'll allways have to convert papers (I love those from Lars Linden) books codes, or anything you can have in Aigamedev are most often in C++. This is extra work. I've look at "Simple Path", the very good Arong Greenberg work but no source provided and AngryAnt work. AI Sandbox : this seems to be exactly what as AI coder I want to use. I saw some preview but from 2009 we still don't know what it will be about precisely, will it be opensource or free (I strongly doubt), will I be able to buy it? will it really provide me tools I need to focus on AI ? That being said, what is the best environment to be able to focus on AI coding only, is it even possible?

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• Persistent (purely functional) Red-Black trees on disk performance

  - by Waneck

  I'm studying the best data structures to implement a simple open-source object temporal database, and currently I'm very fond of using Persistent Red-Black trees to do it. My main reasons for using persistent data structures is first of all to minimize the use of locks, so the database can be as parallel as possible. Also it will be easier to implement ACID transactions and even being able to abstract the database to work in parallel on a cluster of some kind. The great thing of this approach is that it makes possible implementing temporal databases almost for free. And this is something quite nice to have, specially for web and for data analysis (e.g. trends). All of this is very cool, but I'm a little suspicious about the overall performance of using a persistent data structure on disk. Even though there are some very fast disks available today, and all writes can be done asynchronously, so a response is always immediate, I don't want to build all application under a false premise, only to realize it isn't really a good way to do it. Here's my line of thought: - Since all writes are done asynchronously, and using a persistent data structure will enable not to invalidate the previous - and currently valid - structure, the write time isn't really a bottleneck. - There are some literature on structures like this that are exactly for disk usage. But it seems to me that these techniques will add more read overhead to achieve faster writes. But I think that exactly the opposite is preferable. Also many of these techniques really do end up with a multi-versioned trees, but they aren't strictly immutable, which is something very crucial to justify the persistent overhead. - I know there still will have to be some kind of locking when appending values to the database, and I also know there should be a good garbage collecting logic if not all versions are to be maintained (otherwise the file size will surely rise dramatically). Also a delta compression system could be thought about. - Of all search trees structures, I really think Red-Blacks are the most close to what I need, since they offer the least number of rotations. But there are some possible pitfalls along the way: - Asynchronous writes -could- affect applications that need the data in real time. But I don't think that is the case with web applications, most of the time. Also when real-time data is needed, another solutions could be devised, like a check-in/check-out system of specific data that will need to be worked on a more real-time manner. - Also they could lead to some commit conflicts, though I fail to think of a good example of when it could happen. Also commit conflicts can occur in normal RDBMS, if two threads are working with the same data, right? - The overhead of having an immutable interface like this will grow exponentially and everything is doomed to fail soon, so this all is a bad idea. Any thoughts? Thanks! edit: There seems to be a misunderstanding of what a persistent data structure is: http://en.wikipedia.org/wiki/Persistent_data_structure

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• Ubuntu 11.10 power management does not recognize removal of power supply!

  - by sema

  I have a Lenovo Ideapad Z370 with Ubuntu 11.10 and the battery status indicator shows wrong information. Problem: The indicator always shows that the power supply is connected, even if it's not connected. The battery charges and discharges normally. However, the status information is wrong. When charging, the "time to charge" decreases, and when discharging the "time to charge" increases. If the power supply is connected the power statistics show: "Supply Yes" "Online Yes" If it is not connected it shows: "Supply Yes" "Online No" My trials: I tried reinstalling the indicator applet, but that doesn't help. Searching for solutions or similar problems didn't point out any help. Background: The problem occured after I switched the battery mode in Windows. (I use a dual boot system.) Lenovo drivers allow a "battery runtime mode" for maximum runtime and a "battery health mode" for maximum battery lifetime. I initially used the runtime mode, tried the health mode for some time, but switched back to the runtime mode. The problem occured after switching to health mode. Does anyone have an idea what is wrong? The problem is relevant for me as I get no information when battery status low and the computer runs out of energy without shutdown or hibernation. This is really a problem for me!

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• Host grub error after installing Virtualbox - Non Recoverable

  - by BiggJJ

  I have been unable to fine a resolution to my problem and I have been suffering from it for a while. I can install Virtualbox and can reboot the machine successfully straight after. Once the system is back up I can run Virtualbox ans start working towards creating a new machine. So, say I am installing an XP machine. 1 time out of 10 it will work successfully first time. If it doesn't work (i.e BSOD), I delete the machine and start again. But when the time comes to finish up and switch off my computer, but it doesn't happen gracefully. As soon as I click shutdown, The machine dies. When the machine is switched back on I get: Error: no such device grub resuce I boot up my Grub Fix Live CD, but the grub reinstaller get stuck on searching for partitions, gparted just get stuck looking for devices and even fdisk -l drops a line and displays nothing and is the same. Stuck. The only way I know how to sort it is by re-installing Ubuntu. Has anyone had this problem, or know how to fix it?

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• How to explain why design choices are good?

  - by Telastyn

  As I've become a better developer, I find that much of my design skill comes more from intuition than mechanical analysis. This is great. It lets me read code and get a feel for it quicker. It lets me translate designs between languages and abstractions much easier. And it let's me get stuff done faster. The downside is that I find it harder to explain to teammates (and worse, management) why a particular design is advantageous; especially teammates that are behind the times on best practices. "This design is more testable!" or "You should favor composition over inheritance." go right over their heads, and lead into the rabbit hole of me trying to clue everyone in to the last decade of software engineering advances. I'll get better at it with practice of course, but in the mean time it involves a lot of wasted time and/or bad design (that will lead to wasted time fixing it later). How can I better explain why a certain design is superior, when the benefits aren't completely obvious to the audience?

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• Workflow workarounds: tracking individual column changes

  - by PeterBrunone

  This post is long overdue, but since the question keeps popping up on various SharePoint discussion lists, I figured I'd document the answer here (next time I can just post a link instead of typing the whole thing out again).In short, you cannot trigger a SharePoint workflow when a column changes; you can only use the ItemChanged event.  To get more granular, then, you need to add some extra bits.Let's say you have a list called "5K Races" with a column called StartTime, and you want to execute some actions when the StartTime value changes.  Simply perform the following steps:1)  Create an additional column (same datatype) called OldStartTime.2)  When the workflow starts, compare StartTime to OldStartTime.    a) If they are equal, then do nothing (end).    b) If they are NOT equal, proceed with your workflow.3)  If 2b, then set OldStartTime to the value of StartTime.By performing step 3, you ensure that by the end of the workflow, OldStartTime will be equal to StartTime -- this is important because the workflow will continue to run every time a particular item is changed, but by taking away the criterion that would cause the workflow to run the second time, you have avoided an endless loop situation. 

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• Office design and layout for agile development

  - by Adam Eberbach

  (moved from stackoverflow) I have found lot of discussions here on about which keyboard, desk, light or colored background is best - but I can't find one addressing the layout of the whole office. We are a company with about 20 employees moving to a new place, something larger. There are two main development practices going on here with regular combination, the back end people often needing to work with the mobile people to arrange web services. There are about twice as many back end people as mobile people. About half of the back end developers are working on-site at any time and while they are almost never all in the office at once at least 5-10 spaces need to be provided - so most of the time the two groups are about equal. We have the chance to arrange desks, partitions and possibly even walls to make the space good. There won't be cash for dot-com frills like catering or massages but now's the time to be planning to avoid ending up with a bunch of desks in a long line. Joel on Software's Bionic Office is an article I've remembered from way back and it has some good ideas but I* (and more importantly the company's owners) are not completely sold on the privacy idea in an environment where we are supposed to be collaborating. This is another great link - The Ultimate Software Development Office Layout - I hadn't even remembered enclosed meeting rooms until reading this. Does the private office stand in the way of agile development? Is the scrum enough forced contact and if you need to bug someone you should need to get up and knock on their door? What design layouts can you point to and why would you recommend them? *I'm not against closed offices at all but would be happy if some other solution can do just as well. If it can't... well, that's what this question is all about.

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