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  • C socket programming: client send() but server select() doesn't see it

    - by Fantastic Fourier
    Hey all, I have a server and a client running on two different machines where the client send()s but the server doesn't seem to receive the message. The server employs select() to monitor sockets for any incoming connections/messages. I can see that when the server accepts a new connection, it updates the fd_set array but always returns 0 despite the client send() messages. The connection is TCP and the machines are separated by like one router so dropping packets are highly unlikely. I have a feeling that it's not select() but perhaps send()/sendto() from client that may be the problem but I'm not sure how to go about localizing the problem area. while(1) { readset = info->read_set; ready = select(info->max_fd+1, &readset, NULL, NULL, &timeout); } above is the server side code where the server has a thread that runs select() indefinitely. rv = connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)); printf("rv = %i\n", rv); if (rv < 0) { printf("MAIN: ERROR connect() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("connected\n"); sleep(3); char * somemsg = "is this working yet?\0"; rv = send(sockfd, somemsg, sizeof(somemsg), NULL); if (rv < 0) printf("MAIN: ERROR send() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); rv = sendto(sockfd, somemsg, sizeof(somemsg), NULL, &server_address, sizeof(server_address)); if (rv < 0) printf("MAIN: ERROR sendto() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); and this is the client side where it connects and sends messages and returns connected MAIN: rv is 4 MAIN: rv is 4 any comments or insightful insights are appreciated.

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  • Diffrernce between BackgroundWorker.ReportProgress() and Control.Invoke()

    - by ohadsc
    What is the difference between options 1 and 2 in the following? private void BGW_DoWork(object sender, DoWorkEventArgs e) { for (int i=1; i<=100; i++) { string txt = i.ToString(); if (Test_Check.Checked) //OPTION 1 Test_BackgroundWorker.ReportProgress(i, txt); else //OPTION 2 this.Invoke((Action<int, string>)UpdateGUI, new object[] {i, txt}); } } private void BGW_ProgressChanged(object sender, ProgressChangedEventArgs e) { UpdateGUI(e.ProgressPercentage, (string)e.UserState); } private void UpdateGUI(int percent, string txt) { Test_ProgressBar.Value = percent; Test_RichTextBox.AppendText(txt + Environment.NewLine); } Looking at reflector, the Control.Invoke() appears to use: this.FindMarshalingControl().MarshaledInvoke(this, method, args, 1); whereas BackgroundWorker.Invoke() appears to use: this.asyncOperation.Post(this.progressReporter, args); (I'm just guessing these are the relevant function calls.) If I understand correctly, BGW Posts to the WinForms window its progress report request, whereas Control.Invoke uses a CLR mechanism to invoke on the right thread. Am I close? And if so, what are the repercussions of using either ? Thanks

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  • Using boost asio for pub/sub style tcp in a game loop

    - by unohoo
    I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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  • Question about how to implement a c# host application with a plugin-like architecture

    - by devoured elysium
    I want to have an application that works as a Host to many other small applications. Each one of those applications should work as kind of plugin to this main application. I call them plugins not in the sense they add something to the main application, but because they can only work with this Host application as they depend on some of its services. My idea was to have each of those plugins run in a different app domain. The problem seems to be that my host application should have a set of services that my plugins will want to use and from what is my understanding making data flow in and out from different app domains is not that great of a thing. On one hand I'd like them to behave as stand-alone applications(although, as I said, they need to use lots of times the host application services), but on the other hand I'd like that if any of them crashes, my main application wouldn't suffer from it. What is the best (.NET) approach to this kind of situation? Make them all run on the same AppDomain but each one in a different Thread? Use different AppDomains? One for each "plugin"? How would I make them communicate with the Host Application? Any other way of doing this? Although speed is not an issue here, I wouldn't like for function calls to be that much slower than they are when we're working with just a regular .NET application. Thanks

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  • Check if TIFF file is complete

    - by Davi
    I have a FileSystemWatcher monitoring a directory that receives TIF files from a scanning device. Its necessary to check if the scanning process is done and then read a multipage TIF file, otherwise, the FileSystemWatcher will raise the event before the file be fully scanned. I have something like: private void OnFileCreated(...) { while(IsFileLocked(path)) Thread.Sleep(time); // OK to read } This is what is happening: - Scanner creates the file - FileSystemWatcher detects the file, but its in use - Scanner reads the first page to the file - Scanner releases the file - My code leaves the while(FileInUse(path)) - My code reads the incomplete file (problem) - Scanner adds more pages to the file Let's say the scanner is scanning 100 pages, then, when "OK to read", the file will be incomplete (99 pages left). So, its necessary to know if the file is complete or not. Maybe waiting some time to see if the file is modified, but this time span can be up to hours, because the scanner can get idle scanning the same TIF. Other solution would be checking some flag in the TIF file that indicates that the file is not complete(I've looked for this but don't found anything).

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  • how to return a list using SwingWorker

    - by Ender
    I have an assignment where i have to create an Image Gallery which uses a SwingWorker to load the images froma a file, once the image is load you can flip threw the image and have a slideshow play. I am having trouble getting the list of loaded images using SwingWorker. This is what happens in the background it just publishes the results to a TextArea // In a thread @Override public List<Image> doInBackground() { List<Image> images = new ArrayList<Image>(); for (File filename : filenames) { try { //File file = new File(filename); System.out.println("Attempting to add: " + filename.getAbsolutePath()); images.add(ImageIO.read(filename)); publish("Loaded " + filename); System.out.println("Added file" + filename.getAbsolutePath()); } catch (IOException ioe) { publish("Error loading " + filename); } } return images; } } when it is done I just insert the images in a List<Image> and that is all it does. // In the EDT @Override protected void done() { try { for (Image image : get()) { list.add(image); } } catch (Exception e) { } } Also I created an method that returns the list called getImages() what I need to get is the list from getImages() but doesn't seam to work when I call execute() for example MySwingWorkerClass swingworker = new MySwingWorkerClass(log,list,filenames); swingworker.execute(); imageList = swingworker.getImage() Once it reaches the imageList it doesn't return anything the only way I was able to get the list was when i used the run() instead of the execute() is there another way to get the list or is the run() method the only way?. or perhaps i am not understanding the Swing Worker Class.

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  • Python 3.3 Webserver restarting problems

    - by IPDGino
    I have made a simple webserver in python, and had some problems with it before as described here: Python (3.3) Webserver script with an interesting error In that question, the answer was to use a While True: loop so that any crashes or errors would be resolved instantly, because it would just start itself again. I've used this for a while, and still want to make the server restart itself every few minutes, but on Linux for some reason it won't work for me. On windows the code below works fine, but on linux it keeps saying Handler class up here ... ... class Server: def __init__(self): self.server_class = HTTPServer self.server_adress = ('MY IP GOES HERE, or localhost', 8080) global httpd httpd = self.server_class(self.server_adress, Handler) self.main() def main(self): if count > 1: global SERVER_UP_SINCE HOUR_CHECK = int(((count - 1) * RESTART_INTERVAL) / 60) SERVER_UPTIME = str(HOUR_CHECK) + " MINUTES" if HOUR_CHECK > 60: minutes = int(HOUR_CHECK % 60) hours = int(HOUR_CHECK // 60) SERVER_UPTIME = ("%s HOURS, %s MINUTES" % (str(hours), str(minutes))) SERVING_ON_ADDR = self.server_adress SERVER_UP_SINCE = str(SERVER_UP_SINCE) SERVER_RESTART_NUMBER = count - 1 print(""" SERVER INFO ------------------------------------- SERVER_UPTIME: %s SERVER_UP_SINCE: %s TOTAL_FILES_SERVED: %d SERVING_ON_ADDR: %s SERVER_RESTART_NUMBER: %s \n\nSERVER HAS RESTARTED """ % (SERVER_UPTIME, SERVER_UP_SINCE, TOTAL_FILES, SERVING_ON_ADDR, SERVER_RESTART_NUMBER)) else: print("SERVER_BOOT=1\nSERVER_ONLINE=TRUE\nRESTART_LOOP=TRUE\nSERVING_ON_ADDR:%s" % str(self.server_adress)) while True: try: httpd.serve_forever() except KeyboardInterrupt: print("Shutting down...") break httpd.shutdown() httpd.socket.close() raise(SystemExit) return def server_restart(): """If you want the restart timer to be longer, replace the number after the RESTART_INTERVAL variable""" global RESTART_INTERVAL RESTART_INTERVAL = 10 threading.Timer(RESTART_INTERVAL, server_restart).start() global count count = count + 1 instance = Server() if __name__ == "__main__": global SERVER_UP_SINCE SERVER_UP_SINCE = strftime("%d-%m-%Y %H:%M:%S", gmtime()) server_restart() Basically, I make a thread to restart it every 10 seconds (For testing purposes) and start the server. After ten seconds it will say File "/home/username/Desktop/Webserver/server.py", line 199, in __init__ httpd = self.server_class(self.server_adress, Handler) File "/usr/lib/python3.3/socketserver.py", line 430, in __init__ self.server_bind() File "/usr/lib/python3.3/http/server.py", line 135, in server_bind socketserver.TCPServer.server_bind(self) File "/usr/lib/python3.3/socketserver.py", line 441, in server_bind self.socket.bind(self.server_address) OSError: [Errno 98] Address already in use As you can see in the except KeyboardInterruption line, I tried everything to make the server stop, and the program stop, but it will NOT stop. But the thing I really want to know is how to make this server able to restart, without giving some wonky errors.

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  • Producer consumer with qualifications

    - by tgguy
    I am new to clojure and am trying to understand how to properly use its concurrency features, so any critique/suggestions is appreciated. So I am trying to write a small test program in clojure that works as follows: there 5 producers and 2 consumers a producer waits for a random time and then pushes a number onto a shared queue. a consumer should pull a number off the queue as soon as the queue is nonempty and then sleep for a short time to simulate doing work the consumers should block when the queue is empty producers should block when the queue has more than 4 items in it to prevent it from growing huge Here is my plan for each step above: the producers and consumers will be agents that don't really care for their state (just nil values or something); i just use the agents to send-off a "consumer" or "producer" function to do at some time. Then the shared queue will be (def queue (ref [])). Perhaps this should be an atom though? in the "producer" agent function, simply (Thread/sleep (rand-int 1000)) and then (dosync (alter queue conj (rand-int 100))) to push onto the queue. I am thinking to make the consumer agents watch the queue for changes with add-watcher. Not sure about this though..it will wake up the consumers on any change, even if the change came from a consumer pulling something off (possibly making it empty) . Perhaps checking for this in the watcher function is sufficient. Another problem I see is that if all consumers are busy, then what happens when a producer adds something new to the queue? Does the watched event get queued up on some consumer agent or does it disappear? see above I really don't know how to do this. I heard that clojure's seque may be useful, but I couldn't find enough doc on how to use it and my initial testing didn't seem to work (sorry don't have the code on me anymore)

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  • How to Parse an XML (using XELement) having multiple Namespace ?

    - by Subhen
    Hi I , I get the followinng Xresponse after parsing the XML document: <DIDL-Lite xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"> <item id="1182" parentID="40" restricted="1"> <title>Hot Issue</title> </item> As per the earlier thread, When there is a default namespace in the document, you must parse it as if it were a named namespace. For example. XNamespace ns = "urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"; var xDIDL = xResponse.Element(ns + "DIDL-Lite"); But in my case I have four different name space. I am not getting any results after using the following query , I am getting the response , Not Yeilding any results: XNamespace dc = "http://purl.org/dc/elements/1.1/"; var vAudioData = from xAudioinfo in xResponse.Descendants(ns + "DIDL-lite").Elements("item") select new RMSMedia { strAudioTitle = ((string)xAudioinfo.Element(dc + "title")).Trim(), }; I have no clue whats going on as am new to it. Please help

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  • What should be taught in a "Fundamentals of programming" course at university?

    - by Dervin Thunk
    I have started a new question (see here), because I think the topic is of importance in a more general form. The question is now: If you were a professor at a Computer Science Dept. in some university, what would make it into your course? This is a programming course, second term, first year computer science/computer engineering. Remember you have a limited amount of time, and students are of different levels of competence, and some may be scientists, but some will also go on to be programmers in companies of different kinds. You have to cater to all. Bonus: What language? (Although see this question for my current thoughts about this...) Maybe you want to attach a course outline from some university? See here for an even more general question about this. Answer: I can't really summarize this post... I guess it was too subjective. However, it looks like we have to cover the history of computing up to a certain extent, computer architecture (memory, registers, whatever), C, and finally some basic algos and data structures in a problem solving fashion. This will be the bare bones of the course. Thanks all. I will accept the most voted up answer to close the thread, as it should be done.

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  • Possibility of a custom Contacts field with a set list of values and Contacts lookup performance

    - by areyling
    I'm pretty sure it's not viable to do what I'd like to based on some initial research, but I figured it couldn't hurt to ask the community of experts here in case someone knows a way. I'd like to create a custom field for contacts that the user is able to edit from the main Contacts app; however, the user should only be allowed to select from a list of four specific values. A short list of string values would be ideal, but an int with a min/max range would suffice. I'm interested in knowing if it's possible either way, but also wondering if it make sense to go this route performance wise. More specifically, would it be better to look up a contact (based on a phone number) each time a call or SMS message is received or better to store my own set of data (consisting of name, numbers, and the custom field) and just syncing contact info in a thread every so often? Or syncing contacts the first time the app is run and then registering for changes using ContentObserver? Here is a similar question with an answer that explains how to add a custom field to a contact. Thanks in advance.

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  • problm with MANIFEST.MF in jar

    - by Atul
    hi I have created jar in the following folder: /usr/local/bin/niidle.jar. And my MANIFEST.MF file is as follows: Manifest-Version: 1.0 Main-Class: com.ensarm.niidle.web.scraper.NiidleScrapeManager Class-Path: hector-0.6.0-17.jar And I verified that,this 'hector-0.6.0-17.jar' file is also present in the folder: /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar I don't want to give full class-path name in MANIFEST.MF file,because I have to run this jar on other's machine,so I gave only jar file name 'Class-Path=hector-0.6.0-17.jar' in MANIFEST.MF file. Inspite of mentioning the Class-Path in MANIFEST.MF file, when I run this using command: java -jar /usr/local/bin/niidle.jar arguments... It is showing error massage: --Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21) Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 1 more Please give me solution for this error message..

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  • Framework or design pattern for mailing all users of a webapp

    - by Todd Owen
    My app takes care of user registration (with the option to receive email announcements), and can easily handle the actual template-based rendering of email for a given user. JavaMail provides the mail transport layer. But how should I design the application layer between the business objects (e.g. User) and the mail transport? The straightforward approach would be a simple, synchronous loop: iterate through the users, queue the emails, and be done with it. "Queue" might mean sending them straight to the MTA (mail server), or to an in-memory queue to be consumed by another thread. However, I also plan to implement features like throttling the rate of emails, processing bounced emails (NDRs), and maintaining status across application restarts. My intuition is that a good design would decouple this from both the business layer and the mail transport layer as much as possible. I wondered if others had solved this problem before, but after much searching I haven't found any Java libraries which seem to fit this problem. Standalone mail apps such as James or list servers are too large in scope; packages like Spring's MailSender or Commons Email are too small in scope (being basically drop-in replacements for JavaMail). For other languages I haven't found anything appropriate either. I'm curious about how other developers have gone about adding bulk mailing to their applications.

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  • Why does GetWindowThreadProcessId return 0 when called from a service

    - by Marve
    When using the following class in a console application, and having at least one instance of Notepad running, GetWindowThreadProcessId correctly returns a non-zero thread id. However, if the same code is included in a Windows Service, GetWindowThreadProcessId always returns 0 and no exceptions are thrown. Changing the user the service launches under to be the same as the one running the console application didn't alter the result. What causes GetWindowThreadProcessId to return 0 even if it is provided with a valid hwnd? And why does it function differently in the console application and the service? Note: I am running Windows 7 32-bit and targeting .NET 3.5. public class TestClass { [DllImport("user32.dll")] static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId); public void AttachToNotepad() { var processesToAttachTo = Process.GetProcessesByName("Notepad") foreach (var process in processesToAttachTo) { var threadID = GetWindowThreadProcessId(process.MainWindowHandle, IntPtr.Zero); .... } } } Console Code: class Program { static void Main(string[] args) { var testClass = new TestClass(); testClass.AttachToNotepad(); } } Service Code: public class TestService : ServiceBase { private TestClass testClass = new TestClass(); static void Main() { ServiceBase.Run(new TestService()); } protected override void OnStart(string[] args) { testClass.AttachToNotepad(); base.OnStart(args); } protected override void OnStop() { ... } }

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  • Unable to get data from a WCF client

    - by Scott
    I am developing a DLL that will provide sychronized time stamps to multiple applications running on the same machine. The timestamps are altered in a thread that uses a high performance timer and a scalar to provide the appearance of moving faster than real-time. For obvious reasons I want only 1 instance of this time library, and I thought I could use WCF for the other processes to connect to this and poll for timestamps whenever they want. When I connect however I never get a valid time stamp, just an empty DateTime. I should point out that the library does work. The original implementation was a single DLL that each application incorporated and each one was synced using windows messages. I'm fairly sure it has something to do with how I'm setting up the WCF stuff, to which I am still pretty new. Here are the contract definitions: public interface ITimerCallbacks { [OperationContract(IsOneWay = true)] void TimerElapsed(String id); } [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(ITimerCallbacks))] public interface ISimTime { [OperationContract] DateTime GetTime(); } Here is my class definition: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)] public class SimTimeServer: ISimTime The host setup: // set up WCF interprocess comms host = new ServiceHost(typeof(SimTimeServer), new Uri[] { new Uri("net.pipe://localhost") }); host.AddServiceEndpoint(typeof(ISimTime), new NetNamedPipeBinding(), "SimTime"); host.Open(); and the implementation of the interface function server-side: public DateTime GetTime() { if (ThreadMutex.WaitOne(20)) { RetTime = CurrentTime; ThreadMutex.ReleaseMutex(); } return RetTime; } Lastly the client-side implementation: Callbacks myCallbacks = new Callbacks(); DuplexChannelFactory pipeFactory = new DuplexChannelFactory(myCallbacks, new NetNamedPipeBinding(), new EndpointAddress("net.pipe://localhost/SimTime")); ISimTime pipeProxy = pipeFactory.CreateChannel(); while (true) { string str = Console.ReadLine(); if (str.ToLower().Contains("get")) Console.WriteLine(pipeProxy.GetTime().ToString()); else if (str.ToLower().Contains("exit")) break; }

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  • Bash script to insert code from one file at a specific location in another file?

    - by Kurtosis
    I have a fileA with a snippet of code, and I need a script to insert that snippet into fileB on the line after a specific pattern. I'm trying to make the accepted answer in this thread work, but it's not, and is not giving an error so not sure why not: sed -e '/pattern/r text2insert' filewithpattern Any suggestions? pattern (insert snippet on line after): def boot { also tried escaped pattern but no luck: def\ boot\ { def\ boot\ \{ fileA snippet: LiftRules.htmlProperties.default.set((r: Req) => new Html5Properties(r.userAgent)) fileB (Boot.scala): package bootstrap.liftweb import net.liftweb._ import util._ import Helpers._ import common._ import http._ import sitemap._ import Loc._ /** * A class that's instantiated early and run. It allows the application * to modify lift's environment */ class Boot { def boot { // where to search snippet LiftRules.addToPackages("code") // Build SiteMap val entries = List( Menu.i("Home") / "index", // the simple way to declare a menu // more complex because this menu allows anything in the // /static path to be visible Menu(Loc("Static", Link(List("static"), true, "/static/index"), "Static Content"))) // set the sitemap. Note if you don't want access control for // each page, just comment this line out. LiftRules.setSiteMap(SiteMap(entries:_*)) // Use jQuery 1.4 LiftRules.jsArtifacts = net.liftweb.http.js.jquery.JQuery14Artifacts //Show the spinny image when an Ajax call starts LiftRules.ajaxStart = Full(() => LiftRules.jsArtifacts.show("ajax-loader").cmd) // Make the spinny image go away when it ends LiftRules.ajaxEnd = Full(() => LiftRules.jsArtifacts.hide("ajax-loader").cmd) // Force the request to be UTF-8 LiftRules.early.append(_.setCharacterEncoding("UTF-8")) } }

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  • iPhone: Does it ever make sense for an object to retain its delegate?

    - by randombits
    According to the rules of memory management in a non garbage collected world, one is not supposed to retain a the calling object in a delegate. Scenario goes like this: I have a class that inherits from UITableViewController and contains a search bar. I run expensive search operations in a secondary thread. This is all done with an NSOperationQueue and subclasses NSOperation instances. I pass the controller as a delegate that adheres to a callback protocol into the NSOperation. There are edge cases when the application crashes because once an item is selected from the UITableViewController, I dismiss it and thus its retain count goes to 0 and dealloc gets invoked on it. The delegate didn't get to send its message in time as the results are being passed at about the same time the dealloc happens. Should I design this differently? Should I call retain on my controller from the delegate to ensure it exists until the NSOperation itself is dealloc'd? Will this cause a memory leak? Right now if I put a retain on the controller, the crashes goes away. I don't want to leak memory though and need to understand if there are cases where retaining the delegate makes sense. Just to recap. UITableViewController creates an NSOperationQueue and NSOperation that gets embedded into the queue. The UITableViewController passes itself as a delegate to NSOperation. NSOperation calls a method on UITableViewController when it's ready. If I retain the UITableViewController, I guarantee it's there, but I'm not sure if I'm leaking memory. If I only use an assign property, edge cases occur where the UITableViewController gets dealloc'd and objc_msgSend() gets called on an object that doesn't exist in memory and a crash is imminent.

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  • Fastest inline-assembly spinlock

    - by sigvardsen
    I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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  • Silverlight performance with many loaded controls

    - by gius
    I have a SL application with many DataGrids (from Silverlight Toolkit), each on its own view. If several DataGrids are opened, changing between views (TabItems, for example) takes a long time (few seconds) and it freezes the whole application (UI thread). The more DataGrids are loaded, the longer the change takes. These DataGrids that slow the UI chanage might be on other places in the app and not even visible at that moment. But once they are opened (and loaded with data), they slow showing other DataGrids. Note that DataGrids are NOT disposed and then recreated again, they still remain in memory, only their parent control is being hidden and visible again. I have profiled the application. It shows that agcore.dll's SetValue function is the bottleneck. Unfortunately, debug symbols are not available for this Silverlight native library responsible for drawing. The problem is not in the DataGrid control - I tried to replace it with XCeed's grid and the performance when changing views is even worse. Do you have any idea how to solve this problem? Why more opened controls slow down other controls? I have created a sample that shows this issue: http://cenud.cz/PerfTest.zip UPDATE: Using VS11 profiler on the sample provided suggests that the problem could be in MeasureOverride being called many times (for each DataGridCell, I guess). But still, why is it slower as more controls are loaded elsewhere? Is there a way to improve the performance?

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  • How do I keep from running out of memory on graphics for an Android app?

    - by user279112
    I've been working on an Android app in Eclipse, and so far, my program hasn't really grown past midget size. However I've already run into an issue with an Out of Memory error. You see, I've been using graphics comprised solely of bitmaps and PNGs in this program, and recently, when I tried to add a little bit more functionality to the program (mainly including a few more bitmaps and causing an extra sprite to be created), it started crashing in the graphics thread's constructor - sprite's constructor. When I tracked the problem down, it turned out to be an Out of Memory error that is seemingly caused by adding too many picture files to the program and creating Drawables out of them. This would be a problem, as I really don't have that many picture resources worked into that program...maybe 20 or so. I haven't even started to include sound yet. These images aren't all that fancy. My questions are this: 1) Are programs for the Android phone really that limited on how much memory they can employ, or is it probably something other than the 20-30 resource pictures causing that error? 2) If the memory for Android apps is so awful it can't even handle 20-30 picture resources being loaded into Drawables that exist at the same time, then how in the world are you supposed to make decent graphics and sound for that thing? Thanks.

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  • using a While loop to control the value of a keyframe in a timeline in Javafx

    - by dragoknight
    i want to create an animation where the ball will move in one of the 4 sectors of a circle randomly.this will happen 5 times.so,i create a while loop(i<5) and call the random function.i then create an if loop and attach some x and y values according to the random fn value.i then create an timeline object inside the while loop and in the key frame value,i use these x and y values.but when i run the program,what happens is that all the values are being created(x and y values seen through println) but only the last x and y value(for i=5)is being rendered in the screen.the animations for the previous values(1<=i<=4)are not being rendered.Please advise where have i gone wrong? public function run(args:String[]) { var i=0; while(i<5) { var z=gety(); println(z); // var relativeTime:Duration=0s; if(z==1) {xbind=120; ybind=80; } else if(z==2) {xbind=120; ybind=120; } else if(z==3) { xbind=80; ybind=120; } else if(z==4) { xbind=80; ybind=80; } var t:Timeline=Timeline{ //time: bind pos with inverse; repeatCount: Timeline.INDEFINITE autoReverse: true keyFrames: [ KeyFrame{ time: 0s values: [ x => 100.0,y => 100.0]}, KeyFrame{time: 2s values:[x => xbind tween Interpolator.LINEAR, y => ybind tween Interpolator.LINEAR,] }, ] }//end timeline i++; t.play(); Thread.sleep(2000); }//end while }

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  • TransactionRequiredException on OptimisticLockException

    - by João Madureira Pires
    Hi there. I have the following class that generates sequencial Card Numbers. I'm trying to recover from OptimisticLockException, by calling recursively the same method. however, i'm getting TransactionRequiredException. Dows anyone knows how to recover from OptimisticLockException in my case? Thanks a lot in advance @Name("simpleAutoIncrementGenerator") public class SimpleAutoIncrementGenerator extends CardNumberGenerator{ private static final long serialVersionUID = 2869548248468809665L; private int numberOfRetries = 0; @Override public String generateNextNumber(CardInstance cardInstance, EntityManager entityManager) { try{ EntityCard card = (EntityCard)entityManager.find(EntityCard.class, cardInstance.getId()); if(card != null){ String nextNumber = ""; String currentNumber = card.getCurrentCardNumber(); if(currentNumber != null && !currentNumber.isEmpty()){ Long numberToInc = Long.parseLong(currentNumber); numberToInc ++; nextNumber = String.valueOf(numberToInc); card.setCurrentCardNumber(nextNumber); // this is just to cause a OptimisticLock Exception try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } entityManager.persist(card); entityManager.flush(); return nextNumber; } } }catch (OptimisticLockException oLE) { System.out.println("\n\n\n\n OptimisticLockException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (TransactionRequiredException trE) { System.out.println("\n\n\n\n TransactionRequiredException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (StaleObjectStateException e) { System.out.println("\n\n\n\n StaleObjectStateException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } } return null; } }

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  • committing to a branch that's not checked out

    - by intuited
    I'm using git to version my home directories on a couple different machines. I'd like for them to each use separate branches and both pull from a common branch. So most commits should be made to that common branch, unless something specific to that machine is being committed, in which case the commit should go to the checked out, machine-specific branch. Switching branches is clearly not a very good option in this case. It's mentioned in this post that what I want to do is impossible, but I found that answer to be rather blunt and to perhaps not take into account the possibility of using the plumbing commands. Unfortunately I don't have enough reputation to comment on that thread. I rather suspect that there is some way to do this and am hoping to save myself an hour or few of questing for the answer by just asking you good folk. So is it possible to commit to a different branch without checking that branch out first? Ideally I'd like to use the index in the same way that git commit normally does.

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  • How to add deploy.jar to classpath?

    - by dma_k
    I am facing the problem: I need to add ${java.home}/lib/deploy.jar JAR file to classpath in the runtime (dynamically from java). The solution with Thread#setContextClassLoader(ClassLoader) (mentioned here) does not work because of this bug (if somebody can explain what is really a problem – you are welcome). The solution with -Xbootclasspath/a:"%JAVA_HOME%/jre/lib/deploy.jar" does not work well for me, because I want to have "pure executable jar" as a deliverable: no wrapping scripts please (more over %JAVA_HOME% may not be defined in user's environment in Windows for example, plus I need to write a script per platform) The solution with merging deploy.jar file into my deliverable works only if I make a build on Windows platform. Unfortunately, when the deliverable is produced on build server running on Linux, I got Linux-dependant JAR, which does not execute on Windows – it fails with the trace below. I have read How the Java Launcher Finds Classes and Java programming dynamics: Java classes and class loading articles but I've got no extra ideas, how to correctly handle this situation. Any advices or solutions are very welcomed. Trace: java.lang.NoClassDefFoundError: Could not initialize class com.sun.deploy.config.Config at com.sun.deploy.net.proxy.UserDefinedProxyConfig.getBrowserProxyInfo(UserDefinedProxyConfig.java:43) at com.sun.deploy.net.proxy.DynamicProxyManager.reset(DynamicProxyManager.java:235) at com.sun.deploy.net.proxy.DeployProxySelector.reset(DeployProxySelector.java:59) ... java.lang.NullPointerException at com.sun.deploy.net.proxy.DynamicProxyManager.getProxyList(DynamicProxyManager.java:63) at com.sun.deploy.net.proxy.DeployProxySelector.select(DeployProxySelector.java:166)

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  • java bubblesort with acm dialog

    - by qzar
    Hi, the program gives following exception: Exception in thread "main" java.lang.NullPointerException at myclasses.BubbleSort.run(BubbleSort.java:42) at acm.program.Program.runHook(Program.java:1519) at acm.program.Program.startRun(Program.java:1508) at acm.program.Program.start(Program.java:729) at myclasses.BubbleSort.main(BubbleSort.java:49) what is wrong? thank you very much! package myclasses; import acm.program.DialogProgram; public class BubbleSort extends DialogProgram { int[] array; public int[] getArray() { return array; } public void setArray(int[] array) { this.array = array; } void swap(int firstPos, int secondPos) { int temp = array[firstPos]; array[firstPos] = array[secondPos]; array[secondPos] = temp; } public void bubblesort() { int i, j, k; for (i = 1; i < array.length; i++) { j = i; k = array[i]; while (j > 0 && array[j - 1] > k) { array[j] = array[j - 1]; --j; } array[j] = k; } } public void run() { BubbleSort a = new BubbleSort(); a.setArray(new int[] {1, 3, 5, 7, 6, 2}); a.bubblesort(); StringBuffer sb = new StringBuffer(a.array.length * 2); for (int i = 0; i < getArray().length; i++) sb.append(getArray()[i]).append(" "); println(sb); } public static void main(String[] args) { new BubbleSort().start(args); } }

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