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  • How to know why an animation stutters?

    - by Patrick Klug
    I have a few fairly simple animations (moving text around, moving ellipses etc.) and running in full screen (1920x1080 minus the task bar) the WPF Performance Suite reports a good framerate around 50 FPS throughout the animation. Dirty Rect Addition is somewhere around 300 rect/s, the SW frames are between 0 and 4 and the HW frames are between 3 and 5. Video memory usage is around 80 MB. Problem is that the animations stutters every other half second. My machine is a new Dell laptop XPS 15 with the GeForce GT 435 with 2GB memory. - The drivers are up to date. (The same behavior occurs on my netbook (in full screen) as well so I don't think it is hardware related.) If I make the window smaller the stutter goes away. The stutter occurs with the simplest of animations - even with just a couple of elements but adding more elements certainly makes it more noticeable. How can I find out what causes this stutter? When I think of it, I have not actually seen any WPF animations which run smoothly in full screen. Is this even possible?

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  • Program to format every media in c++

    - by AtoMerZ
    Problem: I'm trying to write a program that formats any type of media. So far I've managed to format Hard disk partitions, flash memories, SDRAM, RDX. But there's this last type of media (DVD-RAM) I need to format. My program fails to format this media. I'm using the FormatEx function in fmifs.dll. I had absolutely no idea how to use this function Except for its name and that it resides in fmifs.dll. with the help of this I managed to find a simple program that uses this library. Yet still it doesn't give complete information about how to use it. What I've tried: I'm looking for a full documentation about FormatEx, its parameters, and exactly what values each parameter can take. I tried searching on google and MSDN. This is what I found. First of all this isn't the function I'm working with. But even putting that aside there's not enough information on how to use the function (Like which headers/libraries to use). EDIT: I don't have to use FormatEx if there's an alternative to use please tell.

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  • how to fix my error saying expected expression before 'else'

    - by user292489
    this program intended to read a .txt, a set of numbers, file and wwrite to another two .txt files called even amd odd as follows: #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int i=0,even,odd; int number[i]; // check to make sure that all the file names are entered if (argc != 3) { printf("Usage: executable in_file output_file\n"); exit(0); } FILE *dog = fopen(argv[1], "r"); FILE *feven= fopen(argv[2], "w"); FILE *fodd= fopen (argv[3], "w"); // check whether the file has been opened successfully if (dog == NULL) { printf("File %s cannot open!\n", argv[1]); exit(0); } //odd = fopen(argv[2], "w"); { if (i%2!=1) i++;} fprintf(feven, "%d", even); fscanf(dog, "%d", &number[i]); else { i%2==1; i++;} fprintf(fodd, "%d", odd); fscanf(dog, "%d", &number[i]); fclose(feven); fclose(fodd);

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  • How to find an embedded platform?

    - by gmagana
    I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

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  • How to model has_many with polymorphism?

    - by Daniel Abrahamsson
    I've run into a situation that I am not quite sure how to model. Suppose I have a User class, and a user has many services. However, these services are quite different, for example a MailService and a BackupService, so single table inheritance won't do. Instead, I am thinking of using polymorphic associations together with an abstract base class: class User < ActiveRecord::Base has_many :services end class Service < ActiveRecord::Base validates_presence_of :user_id, :implementation_id, :implementation_type belongs_to :user belongs_to :implementation, :polymorphic = true delegate :common_service_method, :name, :to => :implementation end #Base class for service implementations class ServiceImplementation < ActiveRecord::Base validates_presence_of :user_id, :on => :create has_one :service, :as => :implementation has_one :user, :through => :service after_create :create_service_record #Tell Rails this class does not use a table. def self.abstract_class? true end #Default name implementation. def name self.class.name end protected #Sets up a service object def create_service_record service = Service.new(:user_id => user_id) service.implementation = self service.save! end end class MailService < ServiceImplementation #validations, etc... def common_service_method puts "MailService implementation of common service method" end end #Example usage MailService.create(..., :user_id => user.id) BackupService.create(...., :user_id => user.id) user.services.each do |s| puts "#{user.name} is using #{s.name}" end #Daniel is using MailService, Daniel is using BackupService So, is this the best solution? Or even a good one? How have you solved this kind of problem?

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  • how to update UI controls in cocoa application from background thread

    - by AmitSri
    following is .m code: #import "ThreadLabAppDelegate.h" @interface ThreadLabAppDelegate() - (void)processStart; - (void)processCompleted; @end @implementation ThreadLabAppDelegate @synthesize isProcessStarted; - (void)awakeFromNib { //Set levelindicator's maximum value [levelIndicator setMaxValue:1000]; } - (void)dealloc { //Never called while debugging ???? [super dealloc]; } - (IBAction)startProcess:(id)sender { //Set process flag to true self.isProcessStarted=YES; //Start Animation [spinIndicator startAnimation:nil]; //perform selector in background thread [self performSelectorInBackground:@selector(processStart) withObject:nil]; } - (IBAction)stopProcess:(id)sender { //Stop Animation [spinIndicator stopAnimation:nil]; //set process flag to false self.isProcessStarted=NO; } - (void)processStart { int counter = 0; while (counter != 1000) { NSLog(@"Counter : %d",counter); //Sleep background thread to reduce CPU usage [NSThread sleepForTimeInterval:0.01]; //set the level indicator value to showing progress [levelIndicator setIntValue:counter]; //increment counter counter++; } //Notify main thread for process completed [self performSelectorOnMainThread:@selector(processCompleted) withObject:nil waitUntilDone:NO]; } - (void)processCompleted { //Stop Animation [spinIndicator stopAnimation:nil]; //set process flag to false self.isProcessStarted=NO; } @end I need to clear following things as per the above code. How to interrupt/cancel processStart while loop from UI control? I also need to show the counter value in main UI, which i suppose to do with performSelectorOnMainThread and passing argument. Just want to know, is there anyother way to do that? When my app started it is showing 1 thread in Activity Monitor, but when i started the processStart() in background thread its creating two new thread,which makes the total 3 thread until or unless loop get finished.After completing the loop i can see 2 threads. So, my understanding is that, 2 thread created when i called performSelectorInBackground, but what about the thrid thread, from where it got created? What if thread counts get increases on every call of selector.How to control that or my implementation is bad for such kind of requirements? Thanks

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  • Online file storage similar to Amazon S3

    - by Joel G
    I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe RESTful but extras like mkdir and cp (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

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  • why the main method are not covered? urgent, please help me

    - by Mike.Huang
    main method: public static void main(String[] args) throws Exception { if (args.length != EXPECTED_NUMBER_OF_ARGUMENTS) { System.err.println("Usage - java XFRCompiler ConfigXML PackageXML XFR"); } String configXML = args[0]; String packageXML = args[1]; String xfr = args[2]; AutoConfigCompiler compiler = new AutoConfigCompiler(); compiler.setConfigDocument(loadDocument(configXML)); compiler.setPackageInfoDoc(loadDocument(packageXML)); // compiler.setVisiblityDoc(loadDocument("VisibilityFilter.xml")); compiler.compileModel(xfr); } private static Document loadDocument(String fileName) throws Exception { TXDOMParser parser = (TXDOMParser) ParserFactory.makeParser(TXDOMParser.class.getName()); InputSource source = new InputSource(new FileInputStream(fileName)); parser.parse(source); return parser.getDocument(); } testcase: @Test public void testCompileModel() throws Exception { // construct parameters URL configFile = Thread.currentThread().getContextClassLoader().getResource("Ford_2008_Mustang_Config.xml"); URL packageFile = Thread.currentThread().getContextClassLoader().getResource("Ford_2008_Mustang_Package.xml"); File tmpFile = new File("Ford_2008_Mustang_tmp.xfr"); if(!tmpFile.exists()) { tmpFile.createNewFile(); } String[] args = new String[]{configFile.getPath(),packageFile.getPath(),tmpFile.getPath()}; try { // test main method XFRCompiler.main(args); } catch (Exception e) { assertTrue(true); } try { // test args length is less than 3 XFRCompiler.main(new String[]{"",""}); } catch (Exception e) { assertTrue(true); } tmpFile.delete(); } coverage outputs displayed as the lines from “String configXML = args[0];" in main method are not covered

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  • Auditing front end performance on web application

    - by user1018494
    I am currently trying to performance tune the UI of a company web application. The application is only ever going to be accessed by staff, so the speed of the connection between the server and client will always be considerably more than if it was on the internet. I have been using performance auditing tools such as Y Slow! and Google Chrome's profiling tool to try and highlight areas that are worth targeting for investigation. However, these tools are written with the internet in mind. For example, the current suggestions from a Google Chrome audit of the application suggests is as follows: Network Utilization Combine external CSS (Red warning) Combine external JavaScript (Red warning) Enable gzip compression (Red warning) Leverage browser caching (Red warning) Leverage proxy caching (Amber warning) Minimise cookie size (Amber warning) Parallelize downloads across hostnames (Amber warning) Serve static content from a cookieless domain (Amber warning) Web Page Performance Remove unused CSS rules (Amber warning) Use normal CSS property names instead of vendor-prefixed ones (Amber warning) Are any of these bits of advice totally redundant given the connection speed and usage pattern? The users will be using the application frequently throughout the day, so it doesn't matter if the initial hit is large (when they first visit the page and build their cache) so long as a minimal amount of work is done on future page views. For example, is it worth the effort of combining all of our CSS and JavaScript files? It may speed up the initial page view, but how much of a difference will it really make on subsequent page views throughout the working day? I've tried searching for this but all I keep coming up with is the standard internet facing performance advice. Any advice on what to focus my performance tweaking efforts on in this scenario, or other auditing tool recommendations, would be much appreciated.

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  • urllib2.Request() with data returns empty url

    - by Mr. Polywhirl
    My main concern is the function: getUrlAndHtml() If I manually build and append the query to the end of the uri, I can get the response.url(), but if I pass a dictionary as the request data, the url does not come back. Is there anyway to guarantee the redirected url? In my example below, if thisWorks = True I get back a url, but the returned url is the request url as opposed to a redirect link. On a sidenote, the encoding for .E2.80.93 does not translate to - for some reason? #!/usr/bin/python import pprint import urllib import urllib2 from bs4 import BeautifulSoup from sys import argv URL = 'http://en.wikipedia.org/w/index.php?' def yesOrNo(boolVal): return 'yes' if boolVal else 'no' def getTitleFromRaw(page): return page.strip().replace(' ', '_') def getUrlAndHtml(title, printable=False): thisWorks = False if thisWorks: query = 'title={:s}&printable={:s}'.format(title, yesOrNo(printable)) opener = urllib2.build_opener() opener.addheaders = [('User-agent', 'Mozilla/5.0')] response = opener.open(URL + query) else: params = {'title':title,'printable':yesOrNo(printable)} data = urllib.urlencode(params) headers = {'User-agent':'Mozilla/5.0'}; request = urllib2.Request(URL, data, headers) response = urllib2.urlopen(request) return response.geturl(), response.read() def getSoup(html, name=None, attrs=None): soup = BeautifulSoup(html) if name is None: return None return soup.find(name, attrs) def setTitle(soup, newTitle): title = soup.find('div', {'id':'toctitle'}) h2 = title.find('h2') h2.contents[0].replaceWith('{:s} for {:s}'.format(h2.getText(), newTitle)) def updateLinks(soup, url): fragment = '#' for a in soup.findAll('a', href=True): a['href'] = a['href'].replace(fragment, url + fragment) def writeToFile(soup, filename='out.html', indentLevel=2): with open(filename, 'wt') as out: pp = pprint.PrettyPrinter(indent=indentLevel, stream=out) pp.pprint(soup) print('Wrote {:s} successfully.'.format(filename)) if __name__ == '__main__': def exitPgrm(): print('usage: {:s} "<PAGE>" <FILE>'.format(argv[0])) exit(0) if len(argv) == 2: help = argv[1] if help == '-h' or help == '--help': exitPgrm() if False:''' if not len(argv) == 3: exitPgrm() ''' page = 'Led Zeppelin' # argv[1] filename = 'test.html' # argv[2] title = getTitleFromRaw(page) url, html = getUrlAndHtml(title) soup = getSoup(html, 'div', {'id':'toc'}) setTitle(soup, page) updateLinks(soup, url) writeToFile(soup, filename)

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  • C++ Check Substring of a String

    - by user69514
    I'm trying to check whether or not the second argument in my program is a substring of the first argument. The problem is that it only work if the substring starts with the same letter of the string. .i.e Michigan - Mich (this works) Michigan - Mi (this works) Michigan - igan (this doesn't work) #include <stdio.h> #include <string.h> #include <string> using namespace std; bool my_strstr( string str, string sub ) { bool flag = true; int startPosition = -1; char subStart = str.at(0); char strStart; //find starting position for(int i=0; i<str.length(); i++){ if(str.at(i) == subStart){ startPosition = i; break; } } for(int i=0; i<sub.size(); i++){ if(sub.at(i) != str.at(startPosition)){ flag = false; break; } startPosition++; } return flag; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } string str1 = argv[1]; string str2 = argv[2]; bool result = my_strstr(str1, str2); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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  • Tool to detect use/abuse of String.Concat (where StringBuilder should be used)

    - by Mark Rushakoff
    It's common knowledge that you shouldn't use a StringBuilder in place of a small number of concatenations: string s = "Hello"; if (greetingWorld) { s += " World"; } s += "!"; However, in loops of a significant size, StringBuilder is the obvious choice: string s = ""; foreach (var i in Enumerable.Range(1,5000)) { s += i.ToString(); } Console.WriteLine(s); Is there a tool that I can run on either raw C# source or a compiled assembly to identify where in the source code that String.Concat is being called? (If you're not familiar, s += "foo" is mapped to String.Concat in the IL output.) Obviously, I can't realistically search through an entire project and evaluate every += to identify whether the lvalue is a string. Ideally, it would only point out calls inside a for/foreach loop, but I would even put up with all the false positives of noting every String.Concat. Also, I'm aware that there are some refactoring tools that will automatically refactor my code to use StringBuilder, but I am only interested in identifying the Concat usage at this point. I routinely run Gendarme and FxCop on my code, and neither of those tools identify what I've described.

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  • FileReference.save() duplicates ByteArray

    - by bartekb
    Hi, I've encountered a memory problem using FileReference.save(). My Flash application generates of a lot of data in real-time and needs to save this data to a local file. As I understand, Flash 10 (as opposed to AIR) does not support streaming to a file. But, what's even worse is that FileReference.save() duplicates all the data before saving it. I was looking for a workaround to this doubled memory usage and thought about the following approach: What if I pass a custom subclass of ByteArray as an argument to FileReference.save(), where this ByteArray subclass would override all read*() methods. The overridden read*() methods would wait for a piece of data to be generated by my application, return this piece of data and immediately remove it from the memory. I know how much data will be generated, so I could also override length/bytesAvailable methods. Would it be possible? Could you give me some hint how to do it? I've created a subclass of ByteArray, registered an alias for it, passed an instance of this subclass to FileReference.save(), but somehow FileReference.save() seems to treat it just as it was a ByteArray instance and doesn't call any of my overridden methods... Thanks a lot for any help!

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  • Compact data structure for storing a large set of integral values

    - by Odrade
    I'm working on an application that needs to pass around large sets of Int32 values. The sets are expected to contain ~1,000,000-50,000,000 items, where each item is a database key in the range 0-50,000,000. I expect distribution of ids in any given set to be effectively random over this range. The operations I need on the set are dirt simple: Add a new value Iterate over all of the values. There is a serious concern about the memory usage of these sets, so I'm looking for a data structure that can store the ids more efficiently than a simple List<int>or HashSet<int>. I've looked at BitArray, but that can be wasteful depending on how sparse the ids are. I've also considered a bitwise trie, but I'm unsure how to calculate the space efficiency of that solution for the expected data. A Bloom Filter would be great, if only I could tolerate the false negatives. I would appreciate any suggestions of data structures suitable for this purpose. I'm interested in both out-of-the-box and custom solutions. EDIT: To answer your questions: No, the items don't need to be sorted By "pass around" I mean both pass between methods and serialize and send over the wire. I clearly should have mentioned this. There could be a decent number of these sets in memory at once (~100).

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  • The CLR has been unable to transition from COM context [...] for 60 seconds

    - by BlueRaja The Green Unicorn
    I am getting this error on code that used to work. I have not changed the code. Here is the full error: The CLR has been unable to transition from COM context 0x3322d98 to COM context 0x3322f08 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. And here is the code that caused it: var openFileDialog1 = new System.Windows.Forms.OpenFileDialog(); openFileDialog1.DefaultExt = "mdb"; openFileDialog1.Filter = "Management Database (manage.mdb)|manage.mdb"; //Stalls indefinitely on the following line, then gives the CLR error //one minute later. The dialog never opens. if(openFileDialog1.ShowDialog() == DialogResult.OK) { .... } Yes, I am sure the dialog is not open in the background, and no, I don't have any explicit COM code or unmanaged marshalling or multithreading. I have no idea why the OpenFileDialog won't open - any ideas?

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  • What is the easiest way to add compression to WCF in Silverlight?

    - by caryden
    I have a silverlight 2 beta 2 application that accesses a WCF web service. Because of this, it currently can only use basicHttp binding. The webservice will return fairly large amounts of XML data. This seems fairly wasteful from a bandwidth usage standpoint as the response, if zipped, would be smaller by a factor of 5 (I actually pasted the response into a txt file and zipped it.). The request does have the "Accept-Encoding: gzip, deflate" - Is there any way have the WCF service gzip (or otherwise compress) the response? I did find this link but it sure seems a bit complex for functionality that should be handled out-of-the-box IMHO. OK - at first I marked the solution using the System.IO.Compression as the answer as I could never "seem" to get the IIS7 dynamic compression to work. Well, as it turns out: Dynamic Compression on IIS7 was working al along. It is just that Nikhil's Web Developer Helper plugin for IE did not show it working. My guess is that since SL hands the web service call off to the browser, that the browser handles it "under the covers" and Nikhil's tool never sees the compressed response. I was able to confirm this by using Fiddler which monitors traffic external to the browser application. In fiddler, the response was, in fact, gzip compressed!! The other problem with the System.IO.Compression solution is that System.IO.Compression does not exist in the Silverlight CLR. So from my perspective, the EASIEST way to enable WCF compression in Silverlight is to enable Dynamic Compression in IIS7 and write no code at all.

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  • rails not recognizing project

    - by tipu
    I can create a new project using rails and I can use stuff like rails migration ... and i (correctly) get a error because the sqlite gem is missing. but when i try using rails migration ... with a project i checked out from github, it doesn't recognize that it is a rails project i get: Usage: rails new APP_PATH [options] Options: -d, [--database=DATABASE] # Preconfigure for selected database (options: mysql/oracle/postgresql/sqlite3/frontbase/ibm_db) # Default: sqlite3 -O, [--skip-active-record] # Skip Active Record files [--dev] # Setup the application with Gemfile pointing to your Rails checkout -J, [--skip-prototype] # Skip Prototype files -T, [--skip-test-unit] # Skip Test::Unit files -G, [--skip-git] # Skip Git ignores and keeps -b, [--builder=BUILDER] # Path to an application builder (can be a filesystem path or URL) [--edge] # Setup the application with Gemfile pointing to Rails repository -m, [--template=TEMPLATE] # Path to an application template (can be a filesystem path or URL) -r, [--ruby=PATH] # Path to the Ruby binary of your choice # Default: /usr/bin/ruby1.8 [--skip-gemfile] # Don't create a Gemfile and it goes on. any ideas? edit: it's probably an important detail that earlier my rails wasn't working at all. i had to cp /usr/bin/ruby to /usr/bin/local/ruby

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  • Maven - 'all' or 'parent' project for aggregation?

    - by disown
    For educational purposes I have set up a project layout like so (flat in order to suite eclipse better): -product | |-parent |-core |-opt |-all Parent contains an aggregate project with core, opt and all. Core implements the mandatory part of the application. Opt is an optional part. All is supposed to combine core with opt, and has these two modules listed as dependencies. I am now trying to make the following artifacts: product-core.jar product-core-src.jar product-core-with-dependencies.jar product-opt.jar product-opt-src.jar product-opt-with-dependencies.jar product-all.jar product-all-src.jar product-all-with-dependencies.jar Most of them are fairly straightforward to produce. I do have some problem with the aggregating artifacts though. I have managed to make the product-all-src.jar with a custom assembly descriptor in the 'all' module which downloads the sources for all non-transitive deps, and this works fine. This technique also allows me to make the product-all-with-dependencies.jar. I however recently found out that you can use the source:aggregate goal in the source plugin to aggregate sources of the entire aggregate project. This is also true for the javadoc plugin, which also aggregates through the usage of the parent project. So I am torn between my 'all' module approach and ditching the 'all' module and just use the 'parent' module for all aggregation. It feels unclean to have some aggregate artifacts produced in 'parent', and others produced in 'all'. Is there a way of making an 'product-all' jar in the parent project, or to aggregate javadoc in the 'all' project? Or should I just keep both? Thanks

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  • Should I use IDisposable for purely managed resources?

    - by John Gietzen
    Here is the scenario: I have an object called a Transaction that needs to make sure that only one entity has permission to edit it at any given time. In order to facilitate a long-lived lock, I have the class generating a token object that can be used to make the edits. You would use it like this: var transaction = new Transaction(); using (var tlock = transaction.Lock()) { transaction.Update(data, tlock); } Now, I want the TransactionLock class to implement IDisposable so that its usage can be clear. But, I don't have any unmanaged resources to dispose. however, the TransctionLock object itself is a sort of "unmanaged resource" in the sense that the CLR doesn't know how to properly finalize it. All of this would be fine and dandy, I would just use IDisposable and be done with it. However, my issue comes when I try to do this in the finalizer: ~TransactionLock() { this.Dispose(false); } I want the finalizer to release the transaction from the lock, if possible. How, in the finalizer, do I detect if the parent transaction (this.transaction) has already been finalized? Is there a better pattern I should be using? The Transaction class looks something like this: public sealed class Transaction { private readonly object lockMutex = new object(); private TransactionLock currentLock; public TransactionLock Lock() { lock (this.lockMutex) { if (this.currentLock != null) throw new InvalidOperationException(/* ... */); this.currentLock = new TransactionLock(this); return this.currentLock; } } public void Update(object data, TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); // ... } } internal void ValidateLock(TransactionLock tlock) { if (this.currentLock == null) throw new InvalidOperationException(/* ... */); if (this.currentLock != tlock) throw new InvalidOperationException(/* ... */); } internal void Unlock(TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); this.currentLock = null; } } }

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  • How would I code a complex formula parser manually?

    - by StormianRootSolver
    Hm, this is language - agnostic, I would prefer doing it in C# or F#, but I'm more interested this time in the question "how would that work anyway". What I want to accomplish ist: a) I want to LEARN it - it's about my ego this time, it's for a fun project where I want to show myself that I'm a really good at this stuff b) I know a tiny little bit about EBNF (although I don't know yet, how operator precedence works in EBNF - Irony.NET does it right, I checked the examples, but this is a bit ominous to me) c) My parser should be able to take this: 5 * (3 + (2 - 9 * (5 / 7)) + 9) for example and give me the right results d) To be quite frankly, this seems to be the biggest problem in writing a compiler or even an interpreter for me. I would have no problem generating even 64 bit assembler code (I CAN write assembler manually), but the formula parser... e) Another thought: even simple computers (like my old Sharp 1246S with only about 2kB of RAM) can do that... it can't be THAT hard, right? And even very, very old programming languages have formula evaluation... BASIC is from 1964 and they already could calculate the kind of formula I presented as an example f) A few ideas, a few inspirations would be really enough - I just have no clue how to do operator precedence and the parentheses - I DO, however, know that it involves an AST and that many people use a stack So, what do you think?

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  • wordpress generating slow mysql queries - is it index problem?

    - by tash
    Hello Stack Overflow I've got very slow Mysql queries coming up from my wordpress site. It's making everything slow and I think this is eating up CPU usage. I've pasted the Explain results for the two most frequently problematic queries below. This is a typical result - although very occasionally teh queries do seem to be performed at a more normal speed. I have the usual wordpress indexes on the database tables. You will see that one of the queries is generated from wordpress core code, and not from anything specific - like the theme - for my site. I have a vague feeling that the database is not always using the indexes/is not using them properly... Is this right? Does anyone know how to fix it? Or is it a different problem entirely? Many thanks in advance for any help anyone can offer - it is hugely appreciated Query: [wp-blog-header.php(14): wp()] SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') ORDER BY wp_posts.post_date DESC LIMIT 0, 6 id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE wp_posts ref type_status_date type_status_date 63 const 427 Using where; Using filesort Query time: 34.2829 (ms) 9) Query: [wp-content/themes/LMHR/index.php(40): query_posts()] SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND wp_posts.ID NOT IN ( SELECT tr.object_id FROM wp_term_relationships AS tr INNER JOIN wp_term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy = 'category' AND tt.term_id IN ('217', '218', '223', '224') ) AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') ORDER BY wp_posts.post_date DESC LIMIT 0, 6 id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY wp_posts ref type_status_date type_status_date 63 const 427 Using where; Using filesort 2 DEPENDENT SUBQUERY tr ref PRIMARY,term_taxonomy_id PRIMARY 8 func 1 Using index 2 DEPENDENT SUBQUERY tt eq_ref PRIMARY,term_id_taxonomy,taxonomy PRIMARY 8 antin1_lovemusic2010.tr.term_taxonomy_id 1 Using where Query time: 70.3900 (ms)

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  • Calling Python app/script from C#

    - by Maxim Z.
    I'm building an ASP.NET MVC (C#) site where I want to implement STV (Single Transferable Vote) voting. I've used OpenSTV for voting scenarios before, with great success, but I've never used it programmatically. The OpenSTV Google Code project offers a Python script that allows usage of OpenSTV from other applications: import sys sys.path.append("path to openstv package") from openstv.ballots import Ballots from openstv.ReportPlugins.TextReport import TextReport from openstv.plugins import getMethodPlugins (ballotFname, method, reportFname) = sys.argv[1:] methods = getMethodPlugins("byName") f = open(reportFname, "w") try: b = Ballots() b.loadUnknown(ballotFname) except Exception, msg: print >> f, ("Unable to read ballots from %s" % ballotFname) print >> f, msg sys.exit(-1) try: e = methods[method](b) e.runElection() except Exception, msg: print >> f, ("Unable to count votes using %s" % method) print >> f, msg sys.exit(-1) try: r = TextReport(e, outputFile=f) r.generateReport(); except Exception, msg: print >> f, "Unable to write report" print >> f, msg sys.exit(-1) f.close() Is there a way for me to make such a Python call from my C# ASP.NET MVC site? If so, how? Thanks in advance!

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  • C#. How to pass message from unsafe callback to managed code?

    - by maxima120
    Is there a simple example of how to pass messages from unsafe callback to managed code? I have a proprietary dll which receives some messages packed in structs and all is coming to a callback function. The example of usage is as follows but it calls unsafe code too. I want to pass the messages into my application which is all managed code. *P.S. I have no experience in interop or unsafe code. I used to develop in C++ 8 yrs ago but remember very little from that nightmarish times :) P.P.S. The application is loaded as hell, the original devs claim it processes 2mil messages per sec.. I need a most efficient solution.* static unsafe int OnCoreCallback(IntPtr pSys, IntPtr pMsg) { // Alias structure pointers to the pointers passed in. CoreSystem* pCoreSys = (CoreSystem*)pSys; CoreMessage* pCoreMsg = (CoreMessage*)pMsg; // message handler function. if (pCoreMsg->MessageType == Core.MSG_STATUS) OnCoreStatus(pCoreSys, pCoreMsg); // Continue running return (int)Core.CALLBACKRETURN_CONTINUE; } Thank you.

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  • Learning libraries without books or tutorials

    - by Kawili-wili
    While many ask questions about where to find good books or tutorials, I'd like to take the opposite tack. I consider myself to be an entry-level programmer ready to move up to mid-level. I have written code in c, c++, c#, perl, python, clojure, vb, and java, so I'm not completely clueless. Where I see a problem in moving to the next level is learning to make better use of the literally hundreds upon hundreds of libraries available out there. I seem paralyzed unless there is a specific example in a book or tutorial to hand-hold me, yet I often read in various forums where another programmer attempts to assist with a question. He/she will look through the docs or scan the available classes/methods in their favorite IDE and seem to grok what's going on in a relatively short period of time, even if they had no previous experience with that specific library or function. I yearn to break the umbilical chord of constantly spending hour upon hour searching and reading, searching and reading, searching and reading. Many times there is no book or tutorial, or if there is, the discussion glosses over my specific needs or the examples shown are too far off the path for the usage I had in mind or the information is outdated and makes use of deprecated components or the library itself has fallen out of mainstream, yet is still perfectly usable (but no docs, books, or tutorials to hand-hold). My question is: In the absence of books or tutorials, what is the best way to grok new or unfamiliar libraries? I yearn to slicken the grok path so I can get down to the business of doing what I love most -- coding.

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  • How good is the memory mapped Circular Buffer on Wikipedia?

    - by abroun
    I'm trying to implement a circular buffer in C, and have come across this example on Wikipedia. It looks as if it would provide a really nice interface for anyone reading from the buffer, as reads which wrap around from the end to the beginning of the buffer are handled automatically. So all reads are contiguous. However, I'm a bit unsure about using it straight away as I don't really have much experience with memory mapping or virtual memory and I'm not sure that I fully understand what it's doing. What I think I understand is that it's mapping a shared memory file the size of the buffer into memory twice. Then, whenever data is written into the buffer it appears in memory in 2 places at once. This allows all reads to be contiguous. What would be really great is if someone with more experience of POSIX memory mapping could have a quick look at the code and tell me if the underlying mechanism used is really that efficient. Am I right in thinking for example that the file in /dev/shm used for the shared memory always stays in RAM or could it get written to the hard drive (performance hit) at some point? Are there any gotchas I should be aware of? As it stands, I'm probably going to use a simpler method for my current project, but it'd be good to understand this to have it in my toolbox for the future. Thanks in advance for your time.

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