Search Results

Search found 2327 results on 94 pages for 'signal strength'.

Page 33/94 | < Previous Page | 29 30 31 32 33 34 35 36 37 38 39 40  | Next Page >

  • Good patterns for loose coupling in Java?

    - by Eye of Hell
    Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

    Read the article

  • gdb reverse debugging error

    - by Werner
    Hi, i started to try reverse debugging with gdb 7, followin the tutorial: http://www.sourceware.org/gdb/wiki/ProcessRecord/Tutorial and I thought, great! Then I started to debug a real program which gives an error at the end. So I run it with gdb, and I put a breakpoint just before the place I think the error appears. Then I type "record" in order to start to recrd actions for future reverse-debugging. But after some steps I get Process record doesn't support instruction 0xf0d at address 0x2aaaab4c4b4e. Process record: failed to record execution log. Program received signal SIGTRAP, Trace/breakpoint trap. 0x00002aaaab4c4b4e in memcpy () from /lib64/libc.so.6 (gdb) n Single stepping until exit from function memcpy, which has no line number information. Process record doesn't support instruction 0xf0d at address 0x2aaaab4c4b4e. Process record: failed to record execution log. Program received signal SIGABRT, Aborted. 0x00002aaaab4c4b4e in memcpy () from /lib64/libc.so.6 Before I look at in in detail, I wonder if this feature is still buggy, or if I should start to record from the beginning. Where this "record" error happens, just an object is created as a copy of other: Thanks

    Read the article

  • Creating a service (SERVICE_ACCEPT_SESSIONCHANGE)

    - by Ron
    Hi there, I am trying to create a service following the example documented in the link below: http://msdn.microsoft.com/en-us/library/bb540475(v=VS.85).aspx What I am interested in is to be able to catch user "lock" and "unlock" workstation events. Using the code on from the example provided, I modified the following: Line 15: Original: VOID WINAPI SvcCtrlHandler( DWORD ); Modified: DWORD WINAPI SvcCtrlHandler( DWORD, DWORD, LPVOID, LPVOID ); Line 141: Original: gSvcStatusHandle = RegisterServiceCtrlHandler( SVCNAME, SvcCtrlHandler); Modified: gSvcStatusHandle = RegisterServiceCtrlHandlerEx( SVCNAME, SvcCtrlHandler, NULL); Line 244: Original: SvcStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP; Modified: gSvcStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP|SERVICE_ACCEPT_SESSIONCHANGE; Line 266: Original: VOID WINAPI SvcCtrlHandler( DWORD dwCtrl ) { // Handle the requested control code. switch(dwCtrl) { case SERVICE_CONTROL_STOP: ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 0); // Signal the service to stop. SetEvent(ghSvcStopEvent); ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); return; case SERVICE_CONTROL_INTERROGATE: break; default: break; } }` Modified: DWORD WINAPI SvcCtrlHandler( DWORD dwControl, DWORD dwEventType, LPVOID lpEventData, LPVOID lpContext ) { DWORD dwErrorCode = NO_ERROR; switch(dwControl) { case SERVICE_CONTROL_STOP: ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 0); // Signal the service to stop. SetEvent(ghSvcStopEvent); ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); break; case SERVICE_CONTROL_INTERROGATE: break; case SERVICE_CONTROL_SESSIONCHANGE: ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); break; default: break; } return dwErrorCode; } With the changes above, my service compiled and install fine. But when I try to start my service on my Windows 2000 machine, it does not start properly (it will be stuck on the "starting" status) Can anyone please advise? Thank you in advance, Ron

    Read the article

  • Is it approproate it use django signals withing the same app

    - by Alex Lebedev
    Trying to add email notification to my app in the cleanest way possible. When certain fields of a model change, app should send a notification to a user. Here's my old solution: from django.contrib.auth import User class MyModel(models.Model): user = models.ForeignKey(User) field_a = models.CharField() field_b = models.CharField() def save(self, *args, **kwargs): old = self.__class__.objects.get(pk=self.pk) if self.pk else None super(MyModel, self).save(*args, **kwargs) if old and old.field_b != self.field_b: self.notify("b-changed") # Sevelar more events here # ... def notify(self, event) subj, text = self._prepare_notification(event) send_mail(subj, body, settings.DEFAULT_FROM_EMAIL, [self.user.email], fail_silently=True) This worked fine while I had one or two notification types, but after that just felt wrong to have so much code in my save() method. So, I changed code to signal-based: from django.db.models import signals def remember_old(sender, instance, **kwargs): """pre_save hanlder to save clean copy of original record into `old` attribute """ instance.old = None if instance.pk: try: instance.old = sender.objects.get(pk=instance.pk) except ObjectDoesNotExist: pass def on_mymodel_save(sender, instance, created, **kwargs): old = instance.old if old and old.field_b != instance.field_b: self.notify("b-changed") # Sevelar more events here # ... signals.pre_save.connect(remember_old, sender=MyModel, dispatch_uid="mymodel-remember-old") signals.post_save.connect(on_mymodel_save, sender=MyModel, dispatch_uid="mymodel-on-save") The benefit is that I can separate event handlers into different module, reducing size of models.py and I can enable/disable them individually. The downside is that this solution is more code and signal handlers are separated from model itself and unknowing reader can miss them altogether. So, colleagues, do you think it's worth it?

    Read the article

  • Qt support for VNC

    - by muchala123
    i want to test whether qt is supporting VNC or not. For that i have written a small layout program using Qt library. the source code for the layout program is as follows: layout.cpp #include <QApplication> #include <QHBoxLayout> #include <QSlider> #include <QSpinBox> int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget *window = new QWidget; window->setWindowTitle("Enter The Age of the person"); QSpinBox *spinBox = new QSpinBox; QSlider *slider = new QSlider(Qt::Horizontal); spinBox->setRange(0, 130); slider->setRange(0, 130); QObject::connect(spinBox, SIGNAL(valueChanged(int)), slider, SLOT(setValue(int))); QObject::connect(slider, SIGNAL(valueChanged(int)), spinBox, SLOT(setValue(int))); spinBox->setValue(35); QHBoxLayout *layout = new QHBoxLayout; layout->addWidget(spinBox); layout->addWidget(slider); window->setLayout(layout); window->show(); return app.exec(); } i want to run this as server application on my linux PC.For that what i configured Qt and installed like this. ./configure -qt-gfx-vnc make make install The program is working fine. But if i run the application as VNC server application like ./layout -qws -display VNC:0 i am encountering an error.it says that "_X11TransSocketINETConnect() can't get address for VNC:6000: Temporary failure in name resolution".. pls help me what i need to do. Thanks

    Read the article

  • Why doesn't gcc remove this check of a non-volatile variable?

    - by Thomas
    This question is mostly academic. I ask out of curiosity, not because this poses an actual problem for me. Consider the following incorrect C program. #include <signal.h> #include <stdio.h> static int running = 1; void handler(int u) { running = 0; } int main() { signal(SIGTERM, handler); while (running) ; printf("Bye!\n"); return 0; } This program is incorrect because the handler interrupts the program flow, so running can be modified at any time and should therefore be declared volatile. But let's say the programmer forgot that. gcc 4.3.3, with the -O3 flag, compiles the loop body (after one initial check of the running flag) down to the infinite loop .L7: jmp .L7 which was to be expected. Now we put something trivial inside the while loop, like: while (running) putchar('.'); And suddenly, gcc does not optimize the loop condition anymore! The loop body's assembly now looks like this (again at -O3): .L7: movq stdout(%rip), %rsi movl $46, %edi call _IO_putc movl running(%rip), %eax testl %eax, %eax jne .L7 We see that running is re-loaded from memory each time through the loop; it is not even cached in a register. Apparently gcc now thinks that the value of running could have changed. So why does gcc suddenly decide that it needs to re-check the value of running in this case?

    Read the article

  • Wait on multiple condition variables on Linux without unnecessary sleeps?

    - by Joseph Garvin
    I'm writing a latency sensitive app that in effect wants to wait on multiple condition variables at once. I've read before of several ways to get this functionality on Linux (apparently this is builtin on Windows), but none of them seem suitable for my app. The methods I know of are: Have one thread wait on each of the condition variables you want to wait on, which when woken will signal a single condition variable which you wait on instead. Cycling through multiple condition variables with a timed wait. Writing dummy bytes to files or pipes instead, and polling on those. #1 & #2 are unsuitable because they cause unnecessary sleeping. With #1, you have to wait for the dummy thread to wake up, then signal the real thread, then for the real thread to wake up, instead of the real thread just waking up to begin with -- the extra scheduler quantum spent on this actually matters for my app, and I'd prefer not to have to use a full fledged RTOS. #2 is even worse, you potentially spend N * timeout time asleep, or your timeout will be 0 in which case you never sleep (endlessly burning CPU and starving other threads is also bad). For #3, pipes are problematic because if the thread being 'signaled' is busy or even crashes (I'm in fact dealing with separate process rather than threads -- the mutexes and conditions would be stored in shared memory), then the writing thread will be stuck because the pipe's buffer will be full, as will any other clients. Files are problematic because you'd be growing it endlessly the longer the app ran. Is there a better way to do this? Curious for answers appropriate for Solaris as well.

    Read the article

  • QT QSslError being signaled with the error code set to NoError

    - by Nantucket
    My Problem I compiled OpenSSL into QT to enable OpenSSL support. Everything appeared to go correctly in the compile. However, when I try to use the official HTTP example application that can be found here, everytime I try to download an https page, it will signal two QSslError, each with contents NoError. The types of QSslErrors, including NoError, are documented here, poorly. There is no explanation on why they even included an error type called NoError, or what it means. Bizarrely, the NoError error code seems to be true, as it downloads the remote https document perfectly even while signaling the error. Does anyone have any idea what this means and what could possibly be causing it? Optional Background Reading Here is the relevant part of the code from the example app (this is connected to the network connection's sslErrors signal by the constructor): void HttpWindow::sslErrors(QNetworkReply*,const QList<QSslError> &errors) { QString errorString; foreach (const QSslError &error, errors) { if (!errorString.isEmpty()) errorString += ", "; errorString += error.errorString(); } if (QMessageBox::warning(this, tr("HTTP"), tr("One or more SSL errors has occurred: %1").arg(errorString), QMessageBox::Ignore | QMessageBox::Abort) == QMessageBox::Ignore) { reply->ignoreSslErrors(); } } I have tried the old version of this example, and it produced the same result. I have tried OpenSSL 1.0.0a and 0.9.8o. I have tried tried compiling OpenSSL myself, I have tried using pre-compiled versions of OpenSSL from the net. All produce the same result. If this were my first time using QT with SSL, I would almost think this is the intended result (even though their example application is popping up error warning message windows), if not for the fact that last time I played with QT, using what would now be an old version of QT with an old version of SSL, I distinctly remember everything working fine with no error windows. My system is running Windows 7 x64.

    Read the article

  • QT4 Designer - Implement Widget

    - by MOnsDaR
    I'm currently trying to get into QT4 and figure out a workflow for myself. While trying to create a widget which allows the user to connect to a hostname:port some questions appeared. The widget itself contains a LineEdit for entering the hostname, a SpinBox for entering the port and a PushButton which should emit a connect(QString hostname, unsigned int port) signal. In QTDesigner I created the necessary Form. It is saved as a .ui-File. Now the big question is how could I implement the widget? Is there a place in QTDesigner where I could add my signal to the Widget? Where could I add custom Properties? I've learned in another tutorial, which showed how to create a Widget in C++, how signals, slots, Q_PROPERTIES etc are defined and added to the widget. But there is no sourcecode in QTDesigner. Another option would be to generate sourcecode using uic. But the header says, that another generate would overwrite any changes to the sourcefiles. So how can I create a QT-widget completely with my own signals, slots and properties by using the QTDesigner for creating the UI and not having to recode everything whenever the UI is changing. Is there some kind of Roundtrip-Engineering? If thats not possible: Whats the sense of creating a Widget with QTDesigner then?

    Read the article

  • Validation on ManyToManyField before Save in Models.py

    - by Heyl1
    I have the following models: class Application(models.Model): users = models.ManyToManyField(User, through='Permission') folder = models.ForeignKey(Folder) class Folder(models.Model): company = models.ManyToManyField(Compnay) class UserProfile(models.Model): user = models.OneToOneField(User, related_name='profile') company = models.ManyToManyField(Company) What I would like to do is to check whether one of the users of the Application has the same company as the Application (via Folder). If this is the case the Application instance should not be saved. The problem is that the ManyToManyFields aren't updated until after the 'post-save' signal. The only option seems to be the new m2m_changed signal. But I'm not sure how I then roll back the save that has already happened. Another option would be to rewrite the save function (in models.py, because I'm talking about the admin here), but I'm not sure how I could access the manytomanyfield content. Finally I've read something about rewriting the save function in the admin of the model in admin.py, however I still wouldn't know how you would access the manytomanyfield content. I have been searching for this everywhere but nothing I come across seems to work for me. If anything is unclear, please tell me. Thanks for your help! Heleen

    Read the article

  • Can get members, but not count of NSMutableArray

    - by Curyous
    I'm filling an NSMutableArray from a CoreData call. I can get the first object, but when I try to get the count, the app crashes with Program received signal: “EXC_BAD_ACCESS”. How can I get the count? Here's the relevant code - I've put a comment on the line where it crashes. - (void)viewDidLoad { [super viewDidLoad]; managedObjectContext = [[MySingleton sharedInstance] managedObjectContext]; if (managedObjectContext != nil) { charactersRequest = [[NSFetchRequest alloc] init]; charactersEntity = [NSEntityDescription entityForName:@"Character" inManagedObjectContext:managedObjectContext]; [charactersEntity retain]; [charactersRequest setEntity:charactersEntity]; [charactersRequest retain]; NSError *error; characters = [[managedObjectContext executeFetchRequest:charactersRequest error:&error] mutableCopy]; if (characters == nil) { NSLog(@"Did not get results for characters: %@", error.localizedDescription); } else { [characters retain]; NSLog(@"Found some character(s)."); Character* character = (Character *)[characters objectAtIndex:0]; NSLog(@"Name of first one: %@", character.name); NSLog(@"Found %@ character(s).", characters.count); // Crashes on this line with - Program received signal: “EXC_BAD_ACCESS”. } } } And previous declarations from the header file: @interface CrowdViewController : UITableViewController { NSManagedObjectContext *managedObjectContext; NSFetchRequest *charactersRequest; NSEntityDescription *charactersEntity; NSMutableArray *characters; } I'm a bit perplexed and would really appreciate finding out what is going on.

    Read the article

  • Qt/C++ - confused about caller/callee, object ownership

    - by Isabel
    I am creating a GUI to manipulate a robot arm. The location of the arm can be described by 6 floats (describing the positions of the various arm joints. The interface consists of a QGraphicsView with a diagram of the arm (which can be clicked to change the arm position - adjusting the 6 floats). The interface also has 6 lineEdit boxes, to also adjust those values separately. When the graphics view is clicked, and when the line edit boxes are changed, I'd like the line edit boxes / graphics view to stay in synchronisation. This brings me to confusion about how to store the 6 floats, and trigger events when they're updated. My current idea is this: The robot arm's location should be represented by a class, RobotArmLocation. Objects of this class then have methods such as obj.ShoulderRotation() and obj.SetShoulderRotation(). The MainWindow has a single instance of RobotArmLocation. Next is the bit I'm more confused about, how to join everything up. I am thinking: The MainWindow has a ArmLocationChanged slot. This is signalled whenever the location object is changed. The diagram class will have a SetRobotArmLocation(RobotArmLocation &loc). When the diagram is changed, it's free to change the location object, and fire a signal to the ArmLocationChanged slot. Likewise, changing any of the text boxes will fire a signal to that ArmLocationChanged slot. The slot then has code to synchronise all the elements. This kind of seems like a mess to me, does anyone have any other suggestions? I've also thought of the following, does it have any merrit? The RobotArmLocation class has a ValueChanged slot, the diagram and textboxes can use that directly, and bypass the MainWindow directly (seems cleaner?) thanks for any wisdom!

    Read the article

  • PyQt - QLabel inheriting

    - by Ockonal
    Hello, i wanna inherit QLabel to add there click event processing. I'm trying this code: class NewLabel(QtGui.QLabel): def __init__(self, parent): QtGui.QLabel.__init__(self, parent) def clickEvent(self, event): print 'Label clicked!' But after clicking I have no line 'Label clicked!' EDIT: Okay, now I'm using not 'clickEvent' but 'mousePressEvent'. And I still have a question. How can i know what exactly label was clicked? For example, i have 2 edit box and 2 labels. Labels content are pixmaps. So there aren't any text in labels, so i can't discern difference between labels. How can i do that? EDIT2: I made this code: class NewLabel(QtGui.QLabel): def __init__(self, firstLabel): QtGui.QLabel.__init__(self, firstLabel) def mousePressEvent(self, event): print 'Clicked' #myLabel = self.sender() # None =) self.emit(QtCore.SIGNAL('clicked()'), "Label pressed") In another class: self.FirstLang = NewLabel(Form) QtCore.QObject.connect(self.FirstLang, QtCore.SIGNAL('clicked()'), self.labelPressed) Slot in the same class: def labelPressed(self): print 'in labelPressed' print self.sender() But there isn't sender object in self. What i did wrong?

    Read the article

  • Firing through HTTP a Perl script for sending signals to daemons

    - by Eric Fortis
    Hello guys, I'm using apache2 on Ubuntu. I have a Perl script which basically read the files names of a directory, then rewrites a text file, then sends a signal to a daemon. How can this be done, as secure as possible through a web-page? Actually I can run the code below, but not if I remove the comments. I'm looking for advise considering: Using HTTP Requests? How about Apache file permissions on the directory shown in code? Is htaccess enough to enable user/pass access to the cgi? Should I use a database instead of writing to a file and run a cron querying the db with permission granted to write and send the signal? Granting as less permissions as possible to the webserver. Should I set a VPN? #!/usr/bin/perl -wT use strict; use CGI; #@fileList = </home/user/*>; #read a directory listing my $query = CGI->new(); print $query->header( "text/html" ), $query->p( "FirstFileNameInArray" ), #$query->p( $fileList[0] ), #output the first file in directory $query->end_html;

    Read the article

  • Can FFT length affect filtering accuracy?

    - by Charles
    Hi, I am designing a fractional delay filter, and my lagrange coefficient of order 5 h(n) have 6 taps in time domain. I have tested to convolute the h(n) with x(n) which is 5000 sampled signal using matlab, and the result seems ok. When I tried to use FFT and IFFT method, the output is totally wrong. Actually my FFT is computed with 8192 data in frequency domain, which is the nearest power of 2 for 5000 signal sample. For the IFFT portion, I convert back the 8192 frequency domain data back to 5000 length data in time domain. So, the problem is, why this thing works in convolution, but not in FFT multiplication. Does converting my 6 taps h(n) to 8192 taps in frequency domain causes this problem? Actually I have tried using overlap-save method, which perform the FFT and multiplication with smaller chunks of x(n) and doing it 5 times separately. The result seems slight better than the previous, and at least I can see the waveform pattern, but still slightly distorted. So, any idea where goes wrong, and what is the solution. Thank you.

    Read the article

  • Does Interlocked guarantee visibility to other threads in C# or do I still have to use volatile?

    - by Lirik
    I've been reading the answer to a similar question, but I'm still a little confused... Abel had a great answer, but this is the part that I'm unsure about: ...declaring a variable volatile makes it volatile for every single access. It is impossible to force this behavior any other way, hence volatile cannot be replaced with Interlocked. This is needed in scenarios where other libraries, interfaces or hardware can access your variable and update it anytime, or need the most recent version. Does Interlocked guarantee visibility of the atomic operation to all threads, or do I still have to use the volatile keyword on the value in order to guarantee visibility of the change? Here is my example: public class CountDownLatch { private volatile int m_remain; // <--- do I need the volatile keyword there since I'm using Interlocked? private EventWaitHandle m_event; public CountDownLatch (int count) { Reset(count); } public void Reset(int count) { if (count < 0) throw new ArgumentOutOfRangeException(); m_remain = count; m_event = new ManualResetEvent(false); if (m_remain == 0) { m_event.Set(); } } public void Signal() { // The last thread to signal also sets the event. if (Interlocked.Decrement(ref m_remain) == 0) m_event.Set(); } public void Wait() { m_event.WaitOne(); } }

    Read the article

  • Does playing a Program from VS2005 cause a program to work any different than the .exe file?

    - by Bryan
    There is a program where I work that works fine when running the .exe file but works differently from expected when opened in VS2005 and played from there. I am therefore asking on here if anyone knows of anything that would work in the .exe file but not the debug from VS? I am not able to post the code for the buttons I'm talking about but I'll try to explain the best I can. There is a receiver hooked up to the computer. When the button is pressed on the program, it shows a message and waits for a signal to be received. After the signal is heard the first message box is supposed to close and another is supposed to open. When using the .exe file this happens just fine. However when playing from the program from VS2005 (the same one from which the .exe was made) the second message doesn't come up when it is supposed to and when I can make it come up, the first box doesn't close. There is also a timer involved if that helps. Also, is there a fundamental difference between how the two operate when executing the program? If I need to make anything more clear or give more details please let me know.

    Read the article

  • kernel get stack when signalled

    - by yoavstr
    hi there i write readers and writers where the kernel have to syncronize between them and block writer who already read a massage when i am in the queue waiting I get signal so I do the fallowing while (i_Allready_Read(myf) == ALLREADY_READ || isExistWriter == false ) //while (!(i_Allready_Read(aliveProc,current->pid))) { int i, is_sig = 0; printk(KERN_INFO "\n\n*****entered set in read ******\n\n" ); if (i_Allready_Read(myf) == ALLREADY_READ ) wait_event_interruptible (readWaitQ1, !i_Allready_Read(myf)); else wait_event_interruptible (readWaitQ1, isExistWriter); //printk(KERN_INFO "Read Wakeup %d\n",current->pid); for (i = 0; i < _NSIG_WORDS && !is_sig; i++) { is_sig = current->pending.signal.sig[i] & ~current->blocked.sig[i]; } if (is_sig) { handledClose(myf); module_put (THIS_MODULE); return -EINTR; } } return 0;//success } inline void handledClose(struct file *myf)//v { /* *if we close the writer other writer *would be able to enter to permissiones */ if (myf == writerpid ) { isExistWriter = DOESNT_EXIST; //printk(KERN_INFO "procfs_close : this is pid that just closed %d \n", writerpid); } /* *else its a reader so our numofreaders *need to decremented */ else { removeFromArr(myf); numOfReaders--; } } and my close does nothing ... what did i do wrong?

    Read the article

  • How to cancel a deeply nested process

    - by Mystere Man
    I have a class that is a "manager" sort of class. One of it's functions is to signal that the long running process of the class should shut down. It does this by setting a boolean called "IsStopping" in class. public class Foo { bool isStoping void DoWork() { while (!isStopping) { // do work... } } } Now, DoWork() was a gigantic function, and I decided to refactor it out and as part of the process broke some of it into other classes. The problem is, Some of these classes also have long running functions that need to check if isStopping is true. public class Foo { bool isStoping void DoWork() { while (!isStopping) { MoreWork mw = new MoreWork() mw.DoMoreWork() // possibly long running // do work... } } } What are my options here? I have considered passing isStopping by reference, which I don't really like because it requires there to be an outside object. I would prefer to make the additional classes as stand alone and dependancy free as possible. I have also considered making isStopping a property, and then then having it call an event that the inner classes could be subscribed to, but this seems overly complex. Another option was to create a "Process Cancelation Token" class, similar to what .net 4 Tasks use, then that token be passed to those classes. How have you handled this situation? EDIT: Also consider that MoreWork might have a EvenMoreWork object that it instantiates and calls a potentially long running method on... and so on. I guess what i'm looking for is a way to be able to signal an arbitrary number of objects down a call tree to tell them to stop what they're doing and clean up and return.

    Read the article

  • Is it theoretically possible to emulate a human brain on a computer?

    - by JoelK
    Our brain consists of billions of neurons which basically work with all the incoming data from our senses, handle our consciousness, emotions and creativity as well as our hormone system, etc. So I'm completely new to this topic but doesn't each neuron have a fixed function? E.g.: If a signal of strength x enters, if the last signal was x ms ago, redirect it. From what I've learned in biology about our nerves system which includes our brain because both consist of simple neurons, it seems to me as our brain is one big, complicated computer. Maybe so complicated that things such as intelligence and cognition become possible? As the most complicated things about a neuron pretty much are the chemical aspects on generating an electric singal, keeping itself alive, and eventually segmenting itself, it should be pretty easy emulating some on a computer, or? You won't have to worry about keeping your virtual neuron alive, or? If you can emulate a single neuron on a computer, which shouldn't be too hard, could you theoretically emulate more than 1000 billions of them, recreating intelligence, cognition and maybe even creativity? In my question I'm leaving out the following aspects: Speed of our current (super) computers Actually writing a program for emulating neurons I don't know much about this topic, please tell me if I got anything wrong :) (My secret goal: Make a copy of my brain and store it on some 10 million TB HDD and make someone start it up in the future)

    Read the article

  • throwing exception from APCProc crashes program

    - by lazy_banana
    I started to do some research on how terminate a multithreaded application properly and I found those 2 post(first, second) about how to use QueueUserAPC to signal other threads to terminate. I thought I should give it a try, and the application keeps crashing when I throw the exception from the APCProc. Code: #include <stdio.h> #include <windows.h> class ExitException { public: char *desc; DWORD exit_code; ExitException(char *desc,int exit_code): desc(desc), exit_code(exit_code) {} }; //I use this class to check if objects are deconstructed upon termination class Test { public: char *s; Test(char *s): s(s) { printf("%s ctor\n",s); } ~Test() { printf("%s dctor\n",s); } }; DWORD CALLBACK ThreadProc(void *useless) { try { Test t("thread_test"); SleepEx(INFINITE,true); return 0; } catch (ExitException &e) { printf("Thread exits\n%s %lu",e.desc,e.exit_code); return e.exit_code; } } void CALLBACK exit_apc_proc(ULONG_PTR param) { puts("In APCProc"); ExitException e("Application exit signal!",1); throw e; return; } int main() { HANDLE thread=CreateThread(NULL,0,ThreadProc,NULL,0,NULL); Sleep(1000); QueueUserAPC(exit_apc_proc,thread,0); WaitForSingleObject(thread,INFINITE); puts("main: bye"); return 0; } My question is why does this happen? I use mingw for compilation and my OS is 64bit. Can this be the reason?I read that you shouldn't call QueueApcProc from a 32bit app for a thread which runs in a 64bit process or vice versa, but this shouldn't be the case.

    Read the article

  • QProgressBar problem with uploading

    - by rolanddd
    Hey all! I show my code first, then I explain my problem: ... // somewhere in the constructor progressBar = new QProgressBar(this); progressBar-setMinimum(0); progressBar-setMaximum(100); ... connect(&http, SIGNAL(dataSendProgress(int, int)), this, SLOT(updateProgressBar(int, int))); ... void MainWindow::updateProgressBar(int bytesSent, int total) { progressBar-setMaximum(total); progressBar-setValue(bytesSent); } So this is how I try to make my progressBar being updated when I upload a file. The problem is, it won't do the job. When it starts uploading, I set the value of the progress bar to 0, then (thanks to this slot) it won't actually show the progress, but will jump to 100% immediately (even before it finished uploading). I already checked the HTTP Client example, and copied the progress bar part, it is for downloading, and more or less is the same as for uploading but it uses the dataReadProgress signal (needed for downloading) AND it works perfectly. Does anybody know how to solve this for uploading?

    Read the article

  • Turn based synchronization between threads

    - by Amarus
    I'm trying to find a way to synchronize multiple threads having the following conditions: * There are two types of threads: 1. A single "cyclic" thread executing an infinite loop to do cyclic calculations 2. Multiple short-lived threads not started by the main thread * The cyclic thread has a sleep duration between each cycle/loop iteration * The other threads are allowed execute during the inter-cycle sleep of the cyclic thread: - Any other thread that attempts to execute during an active cycle should be blocked - The cyclic thread will wait until all other threads that are already executing to be finished Here's a basic example of what I was thinking of doing: // Somewhere in the code: ManualResetEvent manualResetEvent = new ManualResetEvent(true); // Allow Externally call CountdownEvent countdownEvent = new CountdownEvent(1); // Can't AddCount a CountdownEvent with CurrentCount = 0 void ExternallyCalled() { manualResetEvent.WaitOne(); // Wait until CyclicCalculations is having its beauty sleep countdownEvent.AddCount(); // Notify CyclicCalculations that it should wait for this method call to finish before starting the next cycle Thread.Sleep(1000); // TODO: Replace with actual method logic countdownEvent.Signal(); // Notify CyclicCalculations that this call is finished } void CyclicCalculations() { while (!stopCyclicCalculations) { manualResetEvent.Reset(); // Block all incoming calls to ExternallyCalled from this point forward countdownEvent.Signal(); // Dirty workaround for the issue with AddCount and CurrentCount = 0 countdownEvent.Wait(); // Wait until all of the already executing calls to ExternallyCalled are finished countdownEvent.Reset(); // Reset the CountdownEvent for next cycle. Thread.Sleep(2000); // TODO: Replace with actual method logic manualResetEvent.Set(); // Unblock all threads executing ExternallyCalled Thread.Sleep(1000); // Inter-cycles delay } } Obviously, this doesn't work. There's no guarantee that there won't be any threads executing ExternallyCalled that are in between manualResetEvent.WaitOne(); and countdownEvent.AddCount(); at the time the main thread gets released by the CountdownEvent. I can't figure out a simple way of doing what I'm after, and almost everything that I've found after a lengthy search is related to producer/consumer synchronization which I can't apply here.

    Read the article

  • Mysql dropping inserts with triggers

    - by user2891127
    Using mysql 5.5. I have two tables. One has a whitelist of hashes. When I insert a new row into the other table, I want to first compare the hash in the insert statement to the whitelist. If it's in the whitelist, I don't want to do the insert (less data to plow through later). The inserts are generated from another program and are text files with sql statements. I've been playing with triggers, and almost have it working: BEGIN IF (select count(md5hash) from whitelist where md5hash=new.md5hash) 0 THEN SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Already Whitelisted'; END IF; END But there's a problem. The Signal throwing up the error stops the import. I want to skip that line, not stop the whole import. Some searching didn't find any way to silently skip the import. My next idea was to create a duplicate table definition, and redirect the insert to that dup table. But the old and new don't seem to apply to table names. Other then adding an ignore column to my table then doing a mass drop based on that column after the import, is there any way to achieve my goal?

    Read the article

  • Modifying Django's pre_save/post_save Data

    - by Rodrogo
    Hi, I'm having a hard time to grasp this post_save/pre_save signals from django. What happens is that my model has a field called status and when a entry to this model is added/saved, it's status must be changed accordingly with some condition. My model looks like this: class Ticket(models.Model): (...) status = models.CharField(max_length=1,choices=OFFERT_STATUS, default='O') And my signal handler, configured for pre_save: def ticket_handler(sender, **kwargs): ticket = kwargs['instance'] (...) if someOtherCondition: ticket.status = 'C' Now, what happens if I put aticket.save() just bellow this last line if statement is a huge iteration black hole, since this action calls the signal itself. And this problem happens in both pre_save and post_save. Well... I guess that the capability of altering a entry before (or even after) saving it is pretty common in django's universe. So, what I'm doing wrong here? Is the Signals the wrong approach or I'm missing something else here? Also, would it be possible to, once this pre_save/post_save function is triggered, to access another model's instance and change a specific row entry on that? Thanks

    Read the article

< Previous Page | 29 30 31 32 33 34 35 36 37 38 39 40  | Next Page >