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• iPhone OpenGL and NSTimer issues

  - by Kyle

  I have an NSTimer that runs at 60hz. With an OpenGL scene loaded and rendering, my game can get 60fps, solid, all day long.. Then if I go and recompile the app, or reload it, it will get 40fps. Same resources loaded. I've been running into this problem for years, and I just want to know why. It's crazy, and I want to know if I should just abandon this stupid Timer. Conditions are not different on my 3GS between loads. It will just get 40fps sometimes. Obviously the clockrate is not different between loads, so the performance figures should be constant given a constant scene. Here is a log of my framerates: A good load: :-) FrameRate: 61 FrameRate: 61 FrameRate: 61 FrameRate: 60 FrameRate: 60 FrameRate: 61 FrameRate: 60 FrameRate: 60 FrameRate: 61 FrameRate: 60 FrameRate: 61 Now, I'll go ahead and do nothing, recompile, and run: FrameRate: 43 FrameRate: 50 FrameRate: 45 FrameRate: 48 FrameRate: 40 FrameRate: 45 FrameRate: 42 FrameRate: 41 FrameRate: 42 FrameRate: 44 FrameRate: 41 FrameRate: 46 ^- Massive difference visually. What the flying heck could cause this? SAME area of the scene, SAME camera setup. No variables are different.

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• How to output JSON from within Django and call it with jQuery from a cross domain?

  - by Emre Sevinç

  For a bookmarklet project I'm trying to get JSON data using jQuery from my server (which is naturally on a different domain) running a Django powered system. According to jQuery docs: "As of jQuery 1.2, you can load JSON data located on another domain if you specify a JSONP callback, which can be done like so: "myurl?callback=?". jQuery automatically replaces the ? with the correct method name to call, calling your specified callback." And for example I can test it successfully in my Firebug console using the following snippet: $.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any& format=json&jsoncallback=?", function(data){ alert(data.title); }); It prints the returned data in an alert window, e.g. 'Recent uploads tagged cat'. However when I try the similar code with my server I don't get anything at all: $.getJSON("http://mydjango.yafz.org/randomTest?jsoncallback=?", function(data){ alert(data.title); }); There are no alert windows and the Firebug status bar says "Transferring data from mydjango.yafz.org..." and keeps on waiting. On the server side I have this: def randomTest(request): somelist = ['title', 'This is a constant result'] encoded = json.dumps(somelist) response = HttpResponse(encoded, mimetype = "application/json") return response I also tried this without any success: def randomTest(request): if request.is_ajax() == True: req = {} req ['title'] = 'This is a constant result.' response = json.dumps(req) return HttpResponse(response, mimetype = "application/json") So to cut a long story short: what is the suggested method of returning a piece of data from within a Django view and retrieve it using jQuery in a cross domain fashion? What are my mistakes above?

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• How can I randomly iterate through a large Range?

  - by void

  I would like to randomly iterate through a range. Each value will be visited only once and all values will eventually be visited. For example: class Array def shuffle ret = dup j = length i = 0 while j > 1 r = i + rand(j) ret[i], ret[r] = ret[r], ret[i] i += 1 j -= 1 end ret end end (0..9).to_a.shuffle.each{|x| f(x)} where f(x) is some function that operates on each value. A Fisher-Yates shuffle is used to efficiently provide random ordering. My problem is that shuffle needs to operate on an array, which is not cool because I am working with astronomically large numbers. Ruby will quickly consume a large amount of RAM trying to create a monstrous array. Imagine replacing (0..9) with (0..99**99). This is also why the following code will not work: tried = {} # store previous attempts bigint = 99**99 bigint.times { x = rand(bigint) redo if tried[x] tried[x] = true f(x) # some function } This code is very naive and quickly runs out of memory as tried obtains more entries. What sort of algorithm can accomplish what I am trying to do? [Edit1]: Why do I want to do this? I'm trying to exhaust the search space of a hash algorithm for a N-length input string looking for partial collisions. Each number I generate is equivalent to a unique input string, entropy and all. Basically, I'm "counting" using a custom alphabet. [Edit2]: This means that f(x) in the above examples is a method that generates a hash and compares it to a constant, target hash for partial collisions. I do not need to store the value of x after I call f(x) so memory should remain constant over time. [Edit3/4/5/6]: Further clarification/fixes.

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• Partial Evaluation of ConstantExpression in ExpressionTreeVisitor

  - by Andrew Theken

  Hi all, I am not an Expression Tree master by any stretch of the imagination, what I have is code that looks like this: int external = 10; using(var session = new Session()) { session.Add(new Product { Name = "test1", Price = 20 }); session.Add(new Product {Name = "test", Price = 10}); var product = session.Products.Where(p => p.Price == external).FirstOrDefault(); Assert.Equal(10, product.Price); } Session implements all the IQueryProvider, IQueryable interfaces you'd come to expect from a LINQ Provider. When I execute the query, everything goes to plan until I read the ConstantExpression for "external", at which point, I am at a loss as to how to move forward because: //constant is ConstantExpression for "external" on the right side of the "p.Price == external" expression above. var t = constant.GetType(); //evaluates to class called "<>c__DisplayClass2" - with a member named "external" that has the value 10. The question is basically.. How can I just access the value of the member "external" - is there a way to accomplish this without using reflection? or am I cooked? What am I missing?

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• android dynamical binding

  - by yoav.str

  I want to work dynamically therefore I want to bind text views dynamically I think an example would explain me the best assuming I want to bind 7 image views i can do it like this : Country = (EditText)findViewById(R.id.CountryEditText); City = (EditText)findViewById(R.id.CityEditText); LivinigCreture = (EditText)findViewById(R.id.LivingCretureE); Nature =(EditText)findViewById(R.id.NatureEditText); Inanimate = (EditText)findViewById(R.id.InanimateEditText); KnowenPersonality = (EditText)findViewById(R.id.KnowenPersonalityEditText); Occupation = (EditText)findViewById(R.id.OccupationEditText); but lets change 7 with NUMOFFILEDS as a final where i want to do the previous ? myImages = new ImageView [7]; for (int i = 0; i<7;i++,????) myImages[i] = (ImageView)findViewById(R.id.initialImageView01); notice : in my R file the R.id.initialImageView01 - R.id.initialImageView07 are not generate in a cont gap between them therefore I don't know how to make this architecture possible . and if there's a way can someone show me an example how to work dynmiclly (like using jsp on android combined way or something ?) id its possiable to do so constant times is it possible to build an the same xml constant num of times like jsp does thank u pep:)

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• Problem with load testing Web Service - VSTS 2008

  - by Carlos

  Hello, I have a webtest with makes a simple call to a WebService which looks like that: MyWebService webService = new MyWebService(); webService.Timeout = 180000; webService.myMethod(); I am not using ThinkTimes, also the Run Duration is set to 5 minutes. When I ran this test simulating only 1 user, I check the counters and I found something like that: Tests Total: 4500 Network Interface\Bytes sent (agent machine): 35,500 Then I ran the same tests, but this time simulating 2 users and I got something like that: Tests Total: 2225 Network Interface\Bytes sent (agent machine): 30,500 So when I increased the numbers of users the tests/sec was half than when I use only 1 user and the bytes sent by the agent was also lower. I think it is strange, because it doesn't seems I have a bottleneck in my agent machine since CPU is never higher than 30% and I have over 1.5GB of RAM free, also my network utilization is like 0.5% of its capacity. In order to troubleshot this I ran a test using Step Pattern, the simulated users went from 20 to 800 users. When I check the requests/sec it is practically constant through the whole test, so it is clear there is something in my test or my environment which is preventing the number of requests from gets higher. It would be a expected behavior if the "response time" was getting higher because it would tell me the requests wasn't been processed properly, but the strange thing is the response time is practically constant all the time and it is pretty low actually. I have no idea why my agent can't send more requests when I increase the numbers of users, any help/tip/guess would be really appreciate.

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• Netlogo: error when putting variable in table, only constants allowe??

  - by Chantal

  Hello, Currently I am working on a Netlogo program where I need to use nodes and links for vehicle routing problem. (links are called streets in the program) Here I have some practical problems of how to input variable linkspeed in a table with another node. Constants like 200 etc are fine. Online I found some examples where variables are used, but I do not know why I keep getting the following error: Expected a constant. (or why netlogo expects a constant) Here is the relevant piece of code: extensions [table] streets-own [linkspeed linktoll] nodes-own [netw] ;; In another piece of code linkspeed is assigned successfully to the links to cheapcalc ;; start conditions set costs very high 300000 ;; state 3 unsearched state 2 searching state 1 searched (for later purposes) ask nodes [ set i 0 set j count nodes set netw table:make while [i < j][ table:put netw (i) [3000000 3] set i (i + 1)]] set i 0 let k 0 ask node 35 ;; here i use node 35 as an example. ;; node 35 is connected to node 34, 36, 20 and 50 [table:put netw (35) [0 1] ;; node need to search costs to travel to itself ;; putting constants is ok. while [i < j] [ask my-links [ask both-ends [if (who != 35) [set color blue ;; set temp ([linkspeed] of street 35 who) ;; here my real goal is to put this in stat of i. but i is easier than linkspeed. table:put netw (who) [ i 2 ] ] ] ] set i (i + 1)] ] ;; next node for later, no it is just repetition of the same. end I hope somebody knows what is going on... Kind regards, Chantal

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• How do I get rid of these warnings?

  - by Brian Postow

  This is really several questions, but anyway... I'm working with a big project in XCode, relatively recently ported from MetroWorks (Yes, really) and there's a bunch of warnings that I want to get rid of. Every so often an IMPORTANT warning comes up, but I never look at them because there's too many garbage ones. So, if I can either figure out how to get XCode to stop giving the warning, or actually fix the problem, that would be great. Here are the warnings: It claims that <map.h> is antiquated. However, when I replace it with <map> my files don't compile. Evidently, there's something in map.h that isn't in map... this decimal constant is unsigned only in ISO C90 This is a large number being compared to an unsigned long. I have even cast it, with no effect. enumeral mismatch in conditional expression: <anonymous enum> vs <anonymous enum> This appears to be from a ?: operator. Possibly that the then and else branches don't evaluate to the same type? Except that in at least one case, it's (matchVp == NULL ? noErr : dupFNErr) And since those are both of type OSErr, which is mac defined... I'm not sure what's up. It also seems to come up when I have other pairs of mac constants... multi-character character constant This one is obvious. The problem is that I actually NEED multi-character constants... -fwritable-strings not compatible with literal CF/NSString I unchecked the "Strings are Read-Only" box in both the project and target settings... and it seems to have had no effect...

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• ExecutorService memory leak on exception

  - by TofuBeer

  I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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• struts2 action not calling properly

  - by Ziplin

  On default I want my struts2 app to forward to an action: <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="false" /> <package name="myApp" namespace="/myApp" extends="struts-default"> <action name="Login_*" method="{1}" class="myApp.SessionManager"> <result name="input">/myApp/Login.jsp</result> <result type="redirectAction">Menu</result> </action> </package> <package name="default" namespace="/" extends="struts-default"> <default-action-ref name="index" /> <action name="index"> <result type="redirectAction"> <param name="actionName">Login_input.action</param> <param name="namespace">/myApp</param> </result> </action> </package> </struts> I'm looking for the application to call SessionManager.input(), but instead it calls SessionManager.execute().

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• DSP - Filter sweep effect

  - by Trap

  I'm implementing a 'filter sweep' effect (I don't know if it's called like that). What I do is basically create a low-pass filter and make it 'move' along a certain frequency range. To calculate the filter cut-off frequency at a given moment I use a user-provided linear function, which yields values between 0 and 1. My first attempt was to directly map the values returned by the linear function to the range of frequencies, as in cf = freqRange * lf(x). Although it worked ok it looked as if the sweep ran much faster when moving through low frequencies and then slowed down during its way to the high frequency zone. I'm not sure why is this but I guess it's something to do with human hearing perceiving changes in frequency in a non-linear manner. My next attempt was to move the filter's cut-off frequency in a logarithmic way. It works much better now but I still feel that the filter doesn't move at a constant perceived speed through the range of frequencies. How should I divide the frequency space to obtain a constant perceived sweep speed? Thanks in advance.

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• Uncrackable anti-piracy protection/DRM even possible? [closed]

  - by some guy

  I hope that this is programming-related enough. You have probably heard about Ubisofts recent steps against piracy. (New DRM requires a constant connection to the Ubisoft server) Many people including me see this as intolerable because the only ones suffering from it at the end are the paying customers. Now to the actual question(s): Ubisoft justified this by calling this mechanism "Uncrackable, only playable by the paying customers". Is a so called uncrackable DRM even possible? You can reverse-engineer and modify everything, even if it takes long. Isn't Ubisoft already lying by calling something not crackable? I mean, hey - With the game you get all its content (textures, models, you know) and some anti-piracy mechanism hardcoded into it. How could that be "uncrackable"? You can just patch the unwanted mechanisms out ---- "Pirates" play the cracked game without problems and the paying customers are the idiots by having constant problems with the game and being unable to play it without a (working) internet connection. What are the points Ubisoft sees in this? If they are at least a bit intelligent and informed they know their anti-piracy protection won't last long. All they get is lower sales, angry customers and happy pirates and crackers.

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• Analyzing Web Application Speed

  - by Amy

  I'm a bit confused because the logical/programmer brain in me says that if all things are constant, the speed of a function must be constant. I am working on a PHP web application with jqGrid as a front end for showing the data. I am testing on my personal computer, so network traffic does not apply. I make an HTTP request to a PHP function, it returns the data, and then jqGrid renders it. What has me befuddled is that sometimes, Firebug reports that this is taking 300-600 milliseconds sometimes, and sometimes, it's taking 3.68 seconds. I can run the request over and over again, with very radically different response times. The query is the same. The number of users on the system is the same. No network latency. Same code. I'm not running other applications on the computer while testing. I could understand query caching improving performance on subsequent requests, but the speed is just fluctuating wildly with no rhyme or reason. So, my question is, what else can cause such variability in the response time? How can I determine what's doing it? More importantly, is there any way to get things more consistent?

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• Initializing PHP class property declarations with simple expressions yields syntax error

  - by user171929

  According to the PHP docs, one can initialize properties in classes with the following restriction: "This declaration may include an initialization, but this initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated." I'm trying to initialize an array and having some issues. While this works fine: public $var = array( 1 => 4, 2 => 5, ); This creates a syntax error: public $var = array( 1 => 4, 2 => (4+1), ); Even this isn't accepted: public $var = 4+1; which suggests it's not a limitation of the array() language construct. Now, the last time I checked, "4+1" equated to a constant value that not only should be accepted, but should in fact be optimized away. In any case, it's certainly able to be evaluated at compile-time. So what's going on here? Is the limitation really along the lines of "cannot be any calculated expression at all", versus any expression "able to be evaluated at compile time"? The use of "evaluated" in the doc's language suggests that simple calculations are permitted, but alas.... If this is a bug in PHP, does anyone have a bug ID? I tried to find one but didn't have any luck.

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• Trouble using termextraction ge

  - by mathee

  I'm trying to install this gem: http://github.com/alexrabarts/term_extraction. It required nokogiri, which I tried installing. I'm getting this as the output: >gem install nokogiri Successfully installed nokogiri-1.4.2.1-x86-mswin32 1 gem installed Installing ri documentation for nokogiri-1.4.2.1-x86-mswin32... No definition for parse_memory No definition for parse_file No definition for parse_with No definition for get_options No definition for set_options Installing RDoc documentation for nokogiri-1.4.2.1-x86-mswin32... No definition for parse_memory No definition for parse_file No definition for parse_with No definition for get_options No definition for set_options I was able to install the termextraction gem (per the README on git repo): >gem install alexrabarts-term_extraction -s http://gems.github.com Successfully installed alexrabarts-term_extraction-0.1.4 1 gem installed Installing ri documentation for alexrabarts-term_extraction-0.1.4... Installing RDoc documentation for alexrabarts-term_extraction-0.1.4... The issue is that I'm trying to test it out, but I'm getting an "uninitialized constant" error when I use it: ActionView::TemplateError (uninitialized constant ApplicationHelper::TermExtraction) on line #3 of app/views/questions/new. haml: 1: %h1 New question 2: -msg = "testing this context thing let's see what it gives me" 3: -getTerms(msg) 4: #new-question-form 5: .box-background 6: -form_for(@question) do |f| app/helpers/application_helper.rb:42:in `getTerms' app/views/questions/new.haml:3:in `_run_haml_app47views47questions47new46haml' haml (2.2.23) lib/haml/helpers/action_view_mods.rb:13:in `render' haml (2.2.23) lib/haml/helpers/action_view_mods.rb:13:in `render' app/controllers/questions_controller.rb:91:in `new' haml (2.2.23) lib/sass/plugin/rails.rb:20:in `process' Here is application_helper.rb: module ApplicationHelper def getTerms(context) yahoo = TermExtraction::Yahoo.new(:api_key => 'myAPIkey', :context => context) end end I'm not sure what the issue is. Any insight would be greatly appreciated!

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• Showing latex commands in text string using mathjax

  - by robezy

  I have a text string, for ex. 'A vehicle travels from A to B, distance {$d} km at constant speed. While returning back to A on same path it {$variation} its speed by {$v} km/hr. The total time of journey is {$t} hours. Find the original speed of vehicle.' The variables in the curly brackets are to be replaced by appropriate latex equation. I'm using php's preg_replace to replace the variables with latex commands. Unfortunately, my latex commands are coming as it is. It is not processed by mathjax. For ex, above text becomes A vehicle travels from A to B, distance 1 km at constant speed. While returning back to A on same path it increased its speed by (\frac{3}{2}) km/hr. The total time of journey is 1 hours. Find the original speed of vehicle. The frac is show as it is. What is wrong here? Please ask me if you need any more info. Thanks

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• ExecutorSerrvice memory leak on exception

  - by TofuBeer

  I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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• What are the arguments against the inclusion of server side scripting in JavaScript code blocks?

  - by James Wiseman

  I've been arguing for some time against embedding server-side tags in JavaScript code, but was put on the spot today by a developer who seemed unconvinced The code in question was a legacy ASP application, although this is largely unimportant as it could equally apply to ASP.NET or PHP (for example). The example in question revolved around the use of a constant that they had defined in ServerSide code. 'VB Const MY_CONST: MY_CONST = 1 If sMyVbVar = MY_CONST Then 'Do Something End If //JavaScript if (sMyJsVar === "<%= MY_CONST%>"){ //DoSomething } My standard arguments against this are: Script injection: The server-side tag could include code that can break the JavaScript code Unit testing. Harder to isolate units of code for testing Code Separation : We should keep web page technologies apart as much as possible. The reason for doing this was so that the developer did not have to define the constant in two places. They reasoned that as it was a value that they controlled, that it wasn't subject to script injection. This reduced my justification for (1) to "We're trying to keep the standards simple, and defining exception cases would confuse people" The unit testing and code separation arguments did not hold water either, as the page itself was a horrible amalgam of HTML, JavaScript, ASP.NET, CSS, XML....you name it, it was there. No code that was every going to be included in this page could possibly be unit tested. So I found myself feeling like a bit of a pedant insisting that the code was changed, given the circumstances. Are there any further arguments that might support my reasoning, or am I, in fact being a bit pedantic in this insistence?

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• Simplification / optimization of GPS track

  - by GreyCat

  I've got a GPS track, produces by gpxlogger(1) (supplied as a client for gpsd). GPS receiver updates its coordinates every 1 second, gpxlogger's logic is very simple, it writes down location (lat, lon, ele) and a timestamp (time) received from GPS every n seconds (n = 3 in my case). After writing down a several hours worth of track, gpxlogger saves several megabyte long GPX file that includes several thousands of points. Afterwards, I try to plot this track on a map and use it with OpenLayers. It works, but several thousands of points make using the map a sloppy and slow experience. I understand that having several thousands of points of suboptimal. There are myriads of points that can be deleted without losing almost anything: when there are several points making up roughly the straight line and we're moving with the same constant speed between them, we can just leave the first and the last point and throw anything else. I thought of using gpsbabel for such track simplification / optimization job, but, alas, it's simplification filter works only with routes, i.e. analyzing only geometrical shape of path, without timestamps (i.e. not checking that the speed was roughly constant). Is there some ready-made utility / library / algorithm available to optimize tracks? Or may be I'm missing some clever option with gpsbabel?

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• What exactly is a reentrant function?

  - by eSKay

  Most of the times, the definition of reentrance is quoted from Wikipedia: A computer program or routine is described as reentrant if it can be safely called again before its previous invocation has been completed (i.e it can be safely executed concurrently). To be reentrant, a computer program or routine: Must hold no static (or global) non-constant data. Must not return the address to static (or global) non-constant data. Must work only on the data provided to it by the caller. Must not rely on locks to singleton resources. Must not modify its own code (unless executing in its own unique thread storage) Must not call non-reentrant computer programs or routines. How is safely defined? If a program can be safely executed concurrently, does it always mean that it is reentrant? What exactly is the common thread between the six points mentioned that I should keep in mind while checking my code for reentrant capabilities? Also, Are all recursive functions reentrant? Are all thread-safe functions reentrant? Are all recursive and thread-safe functions reentrant? While writing this question, one thing comes to mind: Are the terms like reentrance and thread safety absolute at all i.e. do they have fixed concrete definations? For, if they are not, this question is not very meaningful. Thanks!

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• Class initialization and synchronized class method

  - by nybon

  Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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• Given a typical Rails 3 environment, why am I unable to execute any tests?

  - by Tom

  I'm working on writing simple unit tests for a Rails 3 project, but I'm unable to actually execute any tests. Case in point, attempting to run the test auto-generated by Rails fails: require 'test_helper' class UserTest < ActiveSupport::TestCase # Replace this with your real tests. test "the truth" do assert true end end Results in the following error: <internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- test_helper (LoadError) from <internal:lib/rubygems/custom_require>:29:in `require' from user_test.rb:1:in `<main>' Commenting out the require 'test_helper' line and attempting to run the test results in this error: user_test.rb:3:in `<main>': uninitialized constant Object::ActiveSupport (NameError) The action pack gems appear to be properly installed and up to date: actionmailer (3.0.3, 2.3.5) actionpack (3.0.3, 2.3.5) activemodel (3.0.3) activerecord (3.0.3, 2.3.5) activeresource (3.0.3, 2.3.5) activesupport (3.0.3, 2.3.5) Ruby is at 1.9.2p0 and Rails is at 3.0.3. The sample dump of my test directory is as follows: /fixtures /functional /integration /performance /unit -- /helpers -- user_helper_test.rb -- user_test.rb test_helper.rb I've never seen this problem before - I've run the typical rake tasks for preparing the test environment. I have nothing out of the ordinary in my application or environment configuration files, nor have I installed any unusual gems that would interfere with the test environment. Edit Xavier Holt's suggestion, explicitly specifying the path to the test_helper worked; however, this revealed an issue with ActiveSupport. Now when I attempt to run the test, I receive the following error message (as also listed above): user_test.rb:3:in `<main>': uninitialized constant Object::ActiveSupport (NameError) But as you can see above, Action Pack is all installed and update to date.

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• 2D platformer gravity physics with slow-motion

  - by DD

  Hi all, I fine tuned my 2d platformer physics and when I added slow-motion I realized that it is messed up. The problem I have is that for some reason the physics still depends on framerate. So when I scale down time elapsed, every force is scaled down as well. So the jump force is scaled down, meaning in slow-motion, character jumps vertically smaller height and gravity force is scaled down as well so the character goes further in the air without falling. I'm sending update function in hopes that someone can help me out here (I separated vertical (jump, gravity) and walking (arbitrary walking direction on a platform - platforms can be of any angle) vectors): characterUpdate:(float)dt { //Compute walking velocity walkingAcceleration = direction of platform * walking acceleration constant * dt; initialWalkingVelocity = walkingVelocity; if( isWalking ) { if( !isJumping ) walkingVelocity = walkingVelocity + walkingAcceleration; else walkingVelocity = walkingVelocity + Vector( walking acceleration constant * dt, 0 ); } // Compute jump/fall velocity if( !isOnPlatform ) { initialVerticalVelocity = verticalVelocity; verticalVelocity = verticalVelocity + verticalAcceleration * dt; } // Add walking velocity position = position + ( walkingVelocity + initialWalkingVelocity ) * 0.5 * dt; //Add jump/fall velocity if not on a platform if( !isOnPlatform ) position = position + ( verticalVelocity + initialVerticalVelocity ) * 0.5 * dt; verticalAcceleration.y = Gravity * dt; }

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• vs2008, opencv2.1,compile error in cxcore.hpp

  - by Long Gu

  Hi, gurus: I installed opencv2.1, made a new project (proj_A) using vs2008, used it for my computer vision tasks, it works fine. I copied an old project (proj_B, also made using vs2008) from other PC, compile it with ".h" and ".lib" files copied from opencv1.0 (which I did not install onto my PC), it compiles fine. I re-directed ".h" and ".lib" files in proj_B to opencv2.1 folders instead, compiled the proj_B, and then I got these errors from cxcore.hpp: class CV_EXPORTS RNG { public: enum { A=4164903690U, UNIFORM=0, NORMAL=1 }; // errors here, line 936 errors are: 5c:\opencv2.1\include\opencv\cxcore.hpp(936) : error C2143: syntax error : missing '}' before 'constant' 5c:\opencv2.1\include\opencv\cxcore.hpp(936) : error C2059: syntax error : 'constant' 5c:\opencv2.1\include\opencv\cxcore.hpp(936) : error C2143: syntax error : missing ';' before '}' 5c:\opencv2.1\include\opencv\cxcore.hpp(936) : error C2238: unexpected token(s) preceding ';' (400+ similar errors, but I believe the answer should be the same, so only list 1 set here) I compared setting for proj_A and proj_B, made them identical, and find no improvement. proj_A works well, proj_B refuse to compile. May I know what's wrong? Urgent, need to get it solved ASAP! Thanks a lot!

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• GWT - problems with constants in css

  - by hba

  Hi, I'm new to GWT; I'm building a small sample app. I have several CSS files. I'm able to successfully use the ClientBundle and CssResource to assign styles to the elements defined in my UiBinder script. Now I'd like to take it one step further and introduce CSS constants using @def css-rule. The @def works great when I define a constant and use it in the same CSS file. However I cannot use it in another CSS file. When I try to use the @eval rule to evaluate an existing constant the compiler throws an execption: "cannot make a static reference to the non-static method ". Here is an example of what I'm trying to do: ConstantStyle.css @def BACKGROUND red; ConstantStyle.java package abc; import ...; interface ConstantStyle extends cssResource { String BACKGROUND(); } MyStyle.css @eval BACKGROUND abc.ConstantStyle.BACKGROUND(); .myClass {background-color: BACKGROUND;} MyStyle.java package abc; import ...; interface ConstantStyle extends cssResource { String myClass; } MyResources.java package abc; import ...; interface MyResources extends ClientBundle { @Source("ConstantStyle.css") ConstantStyle constantStyle(); @Source("MyStyle.css") MyStyle myStyle(); } Thanks in advance!

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