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  • Reason for .Net UI Element Thread-restriction

    - by Charles Bretana
    We know that it is not possible to execute code that manipulates the properties of any UI element from any thread other than the thread the element was instantiated on... My question is why? I remember that when we used COM user interface elements, (in COM/VB6 days), that all UI elements were created using COM classes and co-classes that stored their resources using a memory model referred to as Thread-Local-Storage (TLS) , but as I recall, this was required because of something relaetd to the way COM components were constructed, and should not be relevant to .Net UI elements. Wha's the underlying reason why this restriction still exists? Is it because the underlying Operating System still uses COM-based Win32 API classes for all UI elements, even the ones manipulated in a managed .Net application ??

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  • C# Dispatcher {"The calling thread cannot access this object because a different thread owns it."}

    - by user359446
    Hi, first I need to say that I´m noob with WPF and C#. Application: Create Mandelbrot Image (GUI) My disptacher works perfektly this this case: private void progressBarRefresh(){ while ((con.Progress) < 99) { progressBar1.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { progressBar1.Value = con.Progress; } )); } } I get the Message (Title) when tring to do this with the below code: bmp = BitmapSource.Create(width, height, 96, 96, pf, null, rawImage, stride); this.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { img.Source = bmp; ViewBox.Child = img; //vllt am schluss } )); I will try to explain how my program works. I created a new Thread (because GUI dont response) for the calculation of the pixels and the colors. In this Thread(Mehtod) I´m using the Dispatcher to Refresh my Image in the ViewBox after the calculations are ready. When I´m dont put the calculation in a seperate Thread then I can refresh or build my Image. PS: Sry for my bad english

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  • Datagridview retains waitcursor when updated from thread

    - by Apeksha
    I have a DataGridView control in my Windows Forms Application. I am adding rows to the grid using a background thread. I change the form's cursor to Waitcursor when the process starts and back to Default when it ends. This works well for the form, but not for the grid. When the form's cursor is changed back to default, the grid's cursor does not change, although the cursor over the rest of the form does. Does this have anything to do with the fact that I am updating the grid from a background thread? (The cursor is being changed from the UI thread).

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  • OpenGL multiple threads, variable handling [closed]

    - by toeplitz
    I have written an OpenGL program which runs in the following way: Main: - Initialize SDL - Create thread which has the OpenGL context: - Renderloop - Set camera (view) matrix with glUniform. - glDrawElements() .... etc. - Swapbuffers(); - Main SDL loop handling input events and such. - Update camera matrix of type glm::mat4. This is how I pass my camera object to the class that handles opengl. Camera *cam = new Camera(); gl.setCam(cam); where void setCam(Camera *camera) { this->camera = camera; } For rendering in the opengl context thread, this happens: glm::mat4 modelView = camera->view * model; glUniformMatrix4fv(shader->bindUniform("modelView"), 1, GL_FALSE, glm::value_ptr(modelView)); In the main program where my SDL and other things are handles I then recompute the view matrix. This his working fine without me using any mutex locks. Is this correct? On the other hand, I add objects to my scene by an "upload queue" and in this case I have to mutex lock my upload queue vector (vector class type) when adding items to it or else the program crashes. In summary: I recompute my matrix in a different thread and then use it in the opengl thread without any mutex lock. Why is this working? Edit: I think my question is similar to what was asked here: Should I lock a variable in one thread if I only need it's value in other threads, and why does it work if I don't?, only in my case it is even more simple with only one matrix being changed.

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  • Another thread safe queue implementation

    - by jensph
    I have a class, Queue, that I tried to make thread safe. It has these three member variables: std::queue<T> m_queue; pthread_mutex_t m_mutex; pthread_cond_t m_condition; and a push and pop implemented as: template<class T> void Queue<T>::push(T value) { pthread_mutex_lock( &m_mutex ); m_queue.push(value); if( !m_queue.empty() ) { pthread_cond_signal( &m_condition ); } pthread_mutex_unlock( &m_mutex ); } template<class T> bool Queue<T>::pop(T& value, bool block) { bool rtn = false; pthread_mutex_lock( &m_mutex ); if( block ) { while( m_queue.empty() ) { pthread_cond_wait( &m_condition, &m_mutex ); } } if( !m_queue.empty() ) { value = m_queue.front(); m_queue.pop(); rtn = true; } pthread_mutex_unlock( &m_mutex ); return rtn; } Unfortunately there are occasional issues that may be the fault of this code. That is, there are two threads and sometimes thread 1 never comes out of push() and at other times thread 2 never comes out of pop() (the block parameter is true) though the queue isn't empty. I understand there are other implementations available, but I'd like to try to fix this code, if needed. Anyone see any issues? The constructor has the appropriate initializations: Queue() { pthread_mutex_init( &mMutex, NULL ); pthread_cond_init( &mCondition, NULL ); } and the destructor, the corresponding 'destroy' calls.

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  • How to unmount a VHD in Windows 7. There is no unmount option.

    - by Triynko
    I mounted a VHD file in Windows 7 using the Disk Manager. Once mounted, there is no option to Unmount it. The only thing close to such an option that I can find is if I click the icon in the taskbar notification area that I use to remove USB devices... there's an option to eject the virtual hard disk. However, when I click that, it says that it's in use and cannot be ejected. Even though... it's not in use, I never even browsed the drive. The disk manager is closed... and the only open files handles to the drive (according to disk performance in task manager) is SYSTEM. Ejecting devices cleanly has been a problem since Windows XP, and it sickens me to see it persist into windows 7.

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  • "Safely remove hardware"...doesn't.

    - by Kev
    I have an external USB harddisk that I have scripted to safely shut down after a backup, so the backup operator can unplug it, and knows not to if the lights are still on for some reason. It's always worked fine using the DevEject command-line utility. This week it failed for some reason: DevEject 1.0 2003 c't/Matthias Withopf Ejecting 'USB Mass Storage Device' [USB\VID_0411&PID_002A\00000704C8D2]...FAILED (23,5) Error ejecting device USB Mass Storage Device, vetoed (15,5)! Worse yet, using the SRH tray icon, I click Stop, click OK, it pauses about 5 seconds with OK and Cancel greyed out, closes the sub-window, and then the main window with the Stop button still shows the device, and Stop is still available. I can keep doing that and it never gets rid of the device. I can still access it in Explorer. LockHunter reports that nothing is locking the drive. I've made no changes to the backup configuration or anything to do with the drive this week. Why the sudden flake-out? Short of a restart, which I can't do today before the backup operator goes home, how do I fix it?

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  • how to login as admin in safemode?

    - by Peter
    My sister has forgotten her password to vista, however i have installed that system so should know the admin password. However I do not know how to log in as admin. i tried to press ctrl+alt+delete twice in safemode to switch to normal login mode, but its not working. I heard that admin account is by default turned off in vista, so it might not work.

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  • Safemode Startup Issues on Vista 64 Bit

    - by GnrlBzik
    Before i ask the question, let me point out that this is not a hardware issue. I have a clean install of vista on another hd that runs on same hardware, i am pretty sure its a corruption of a drive or a file, i presume it might be video driver. When windows wont start via normal boot i just get black screen after initial load up of os, so i boot into savemode, I end up having black screen with a mouse pointer visible, after initial load of os. The shut down button is responsive. Of course, I can install clean copy of os, and prior to that can retrieve all other files that i need by accessing hd itself, i can restore my pc from my external back up as well. Although i have all these options, i was wondering if there anything else i can do that can help me fix this issue. In save mode, it looks like I am capable of logging in after initial load of os, even though i cant see the process it self, i do see the mouse pointer. By visual memory i navigated to password field, and entered my password, hit enter, I get the loading mouse pointer, nothing really changes, same black screen and mouse pointer, but when i tried to access task manager for a second i got a safemode watermark at all four corners. Any help would be appriciated. Thank you in advance.

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  • what are security implications of running Ubuntu inside Windows 7?

    - by EndangeringSpecies
    I am thinking of switching to Ubuntu as a way of making web browsing more secure. So, suppose I will go the easy route and run Ubuntu as an app inside Windows and then run Firefox inside of that. What will this do to the security given the current threat environment? E.g. do most online threats nowadays target the browser and flash (which presumably would be safely sandboxed inside easy to wipe Ubuntu environment) or do they target the Windows TCP-IP stack where Ubuntu would give no protection? Well, most likely the above question does not come near to covering all the security implications of this setup :-), so please do discuss whatever other issues that may be relevant here.

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  • Is there a way to disable safe_mode in a client or domain template in Plesk?

    - by Justin
    Is there a way to disable the PHP setting safe_mode in a client or domain template in Plesk 8.6? Or, to disable it for new domain creation in some other Plesk setting/configuration? I've Googled, and people seem to think no I've asked our hosting provider, and they don't think so I've looked in both the domain and client templates in Plesk and don't see it Has anyone been able to do this Plesk 8.6 for new domains?

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  • How do I start mysqld with options

    - by xiankai
    I need to start up mysqld with command line options as from here: http://dev.mysql.com/doc/refman/5.1/en/server-options.html#option_mysqld_skip-grant-tables I normally do sudo service mysqld start, but passing the option as sudo service mysqld start --skip-grant-tables does not seem to work. Alternatively I have tried starting as a daemon, sudo mysqld_safe --skip-grant-tables & But it seems to terminate too soon: 131101 04:59:57 mysqld_safe Logging to '/var/lib/mysql/vagrant.example.com.err'. 131101 04:59:57 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 131101 05:00:03 mysqld_safe mysqld from pid file /var/lib/mysql/vagrant.example.com.pid ended My last option seems to specify the option in /etc/my.cnf instead, but is there any way to do it via the command line?

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  • What is the best way to browse the web safely? [closed]

    - by cedivad
    At the recent pwnown we saw every single browser, from IE to Chrome, miserably hacked. That scares me. How should we browse the Internet safely but continuing to enjoy it? (using lynx is not an option) Virtual machines? Different users with non-administrative privileges? Keep the work and "Facebook" on 2 separate machines? (or on 2 hard disks, invisible each other?) I think that they should write a book on the matter.

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  • Feedback on iterating over type-safe enums

    - by Sumant
    In response to the earlier SO question "Enumerate over an enum in C++", I came up with the following reusable solution that uses type-safe enum idiom. I'm just curious to see the community feedback on my solution. This solution makes use of a static array, which is populated using type-safe enum objects before first use. Iteration over enums is then simply reduced to iteration over the array. I'm aware of the fact that this solution won't work if the enumerators are not strictly increasing. template<typename def, typename inner = typename def::type> class safe_enum : public def { typedef typename def::type type; inner val; static safe_enum array[def::end - def::begin]; static bool init; static void initialize() { if(!init) // use double checked locking in case of multi-threading. { unsigned int size = def::end - def::begin; for(unsigned int i = 0, j = def::begin; i < size; ++i, ++j) array[i] = static_cast<typename def::type>(j); init = true; } } public: safe_enum(type v = def::begin) : val(v) {} inner underlying() const { return val; } static safe_enum * begin() { initialize(); return array; } static safe_enum * end() { initialize(); return array + (def::end - def::begin); } bool operator == (const safe_enum & s) const { return this->val == s.val; } bool operator != (const safe_enum & s) const { return this->val != s.val; } bool operator < (const safe_enum & s) const { return this->val < s.val; } bool operator <= (const safe_enum & s) const { return this->val <= s.val; } bool operator > (const safe_enum & s) const { return this->val > s.val; } bool operator >= (const safe_enum & s) const { return this->val >= s.val; } }; template <typename def, typename inner> safe_enum<def, inner> safe_enum<def, inner>::array[def::end - def::begin]; template <typename def, typename inner> bool safe_enum<def, inner>::init = false; struct color_def { enum type { begin, red = begin, green, blue, end }; }; typedef safe_enum<color_def> color; template <class Enum> void f(Enum e) { std::cout << static_cast<unsigned>(e.underlying()) << std::endl; } int main() { std::for_each(color::begin(), color::end(), &f<color>); color c = color::red; }

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  • Trouble in ActiveX multi-thread invoke javascript callback routine

    - by code0tt
    everyone. I'm get some trouble in ActiveX programming with ATL. I try to make a activex which can async-download files from http server to local folder and after download it will invoke javascript callback function. My solution: run a thread M to monitor download thread D, when D is finish the job, M is going to terminal themself and invoke IDispatch inferface to call javascript function. **************** THERE IS MY CODE: **************** /* javascript code */ funciton download() { var xfm = new ActiveXObject("XFileMngr.FileManager.1"); xfm.download( 'http://somedomain/somefile','localdev:\\folder\localfile',function(msg){alert(msg);}); } /* C++ code */ // main routine STDMETHODIMP CFileManager::download(BSTR url, BSTR local, VARIANT scriptCallback) { CString csURL(url); CString csLocal(local); CAsyncDownload download; download.Download(this, csURL, csLocal, scriptCallback); return S_OK; } // parts of CAsyncDownload.h typedef struct tagThreadData { CAsyncDownload* pThis; } THREAD_DATA, *LPTHREAD_DATA; class CAsyncDownload : public IBindStatusCallback { private: LPUNKNOWN pcaller; CString csRemoteFile; CString csLocalFile; CComPtr<IDispatch> spCallback; public: void onDone(HRESULT hr); HRESULT Download(LPUNKNOWN caller, CString& csRemote, CString& csLocal, VARIANT callback); static DWORD __stdcall ThreadProc(void* param); }; // parts of CAsyncDownload.cpp void CAsyncDownload::onDone(HRESULT hr) { if(spCallback) { TRACE(TEXT("invoke callback function\n")); CComVariant vParams[1]; vParams[0] = "callback is working!"; DISPPARAMS params = { vParams, NULL, 1, 0 }; HRESULT hr = spCallback->Invoke(0, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &params, NULL, NULL, NULL); if(FAILED(hr)) { CString csBuffer; csBuffer.Format(TEXT("invoke failed, result value: %d \n"),hr); TRACE(csBuffer); }else { TRACE(TEXT("invoke was successful\n")); } } } HRESULT CAsyncDownload::Download(LPUNKNOWN caller, CString& csRemote, CString& csLocal, VARIANT callback) { CoInitializeEx(NULL, COINIT_MULTITHREADED); csRemoteFile = csRemote; csLocalFile = csLocal; pcaller = caller; switch(callback.vt){ case VT_DISPATCH: case VT_VARIANT:{ spCallback = callback.pdispVal; } break; default:{ spCallback = NULL; } } LPTHREAD_DATA pData = new THREAD_DATA; pData->pThis = this; // create monitor thread M HANDLE hThread = CreateThread(NULL, 0, ThreadProc, (void*)(pData), 0, NULL); if(!hThread) { delete pData; return HRESULT_FROM_WIN32(GetLastError()); } WaitForSingleObject(hThread, INFINITE); CloseHandle(hThread); CoUninitialize(); return S_OK; } DWORD __stdcall CAsyncDownload::ThreadProc(void* param) { LPTHREAD_DATA pData = (LPTHREAD_DATA)param; // here, we will create http download thread D // when download job is finish, call onDone method; pData->pThis->onDone(S_OK); delete pData; return 0; } **************** CODE FINISH **************** OK, above is parts of my source code, if I call onDone method in sub-thread, I will get OLE ERROR(-2147418113 (8000FFFF) Catastrophic failure.). Did I miss something? please help me to figure it out.

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  • WPF Databinding thread safety?

    - by Petoj
    Well lets say i have an object that i databind to, it implements INotifyPropertyChanged to tell the GUI when a value has changed... if i trigger this from a different thread than the GUI thread how would wpf behave? and will it make sure that it gets the value of the property from memory and not the cpu cache? more or less im asking if wpf does lock() on the object containing the property...

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  • Visual Studio / Visual Source Safe / Integrated Security / IIS 7

    - by Jason
    Using Visual Source Safe with IIS integration (the working dir is the IIS site) Visual Studio, pointed to the IIS site would load up the Web project. It would be under VSS control (have to check out files, etc). Recently, we had to switch to Integrated Security for our database connections from the web app. This means changing the impersonation of the IIS app pool (and anon authentication) to the impersonated account. Since I did this -- my project loads in Visual Studio, but it acts as if I'm not me, and the files aren't under source control anymore. I'm going to assume it's something with the pass-through from IIS to the VSS (as if you'll remember you had to add IIS_USERS to the VSS list of users). Even trying to add the impersonated account didn't work. Any ideas?

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  • SerialPort ReadLine() after Thread.Sleep() goes crazy

    - by Mat
    Hi everybody, I've been fighting with this issue for a day and I can't find answer for it. I am trying to read data from GPS device trough COM port in Compact Framework C#. I am using SerialPort class (actually my own ComPort class boxing SerialPort, but it adds only two fields I need, nothing special). Anyway.. I am running while loop in a separate thread which reads line from the port, analyze NMEA data, print them, catch all exceptions and then I Sleep(200) the thread, cause I need CPU for other threads... Without Sleep it works fine, but uses 100% CPU.. When I dont use Sleep after few minutes the output from COM port looks like this: GPGSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F GSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F A,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,18,12,271,24,24,05,020,24,14,04,326,25,11,03,023,*76 A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F as you can see the same message is read few times but cut. I wonder what I'm doing wrong... My port configuration: port.ReadBufferSize = 4096; port.BaudRate = 4800; port.DataBits = 8; port.Parity = Parity.None; port.StopBits = StopBits.One; port.NewLine = "\r\n"; port.ReadTimeout = 1000; port.ReceivedBytesThreshold = 100000; And my reading function: private void processGps(){ while (!closing) { //reconnect if needed try { string sentence = port.ReadLine(); //here print the sentence //analyze the sentence (this takes some time 50-100ms) } catch (TimeoutException) { Thread.Sleep(0); } catch (IOException ioex) { //handling IO exception (some info on the screen) } Thread.Sleep(200); } } There is some more stuff in this function like reconnection if the device is lost etc.. but it is not called when the GPS is connected properly.. I was trying port.DiscardInBuffer(); after some blocks of code (in TimeoutException, after read..) Did anyone had similar problem? I really dont know what I'm doing wrong.. The only way to get rig of it is removing the last Sleep... Thanks in advance! Best Regards, Mat

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  • WPF How to stop animation from a thread in background worker

    - by toni
    Hi! I have a task that takes a long time. I do it with a background worker thread and before start it, since Do_Work I begin an animation over a label and when task finishes, I stop it in RunWorkerCompleted but I received an error because I try to begin/stop animation in the background thread that is not the owner. How can I do this, I mean to begin/stop animation in the background worker? thanks!

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  • UrlEncoding-Safe Delimiter

    - by Aren B
    So the site I'm working on has a filter system that operates by passing a key and value system through a querystring. The whole site is going through a re-factor soon and I'm maintaining the existing site so before we discuss the RIGHT way to implement this, I just need ideas for changing my delimiter. The current format is like this: cf=<key>:<value> The problem is, I've recently run into an issue because some of our new values for this filter contain : in them. I.e: cf=MO_AspectRatio:16:10 The value is being UrlEncoded, but the browsers are de-coding %3a into : on the fly because the : doesn't inherently break the urls. I need some suggestions for url-safe delimiters that aren't :,-,_,&,? that makes sense. I'm not looking for a solution like () or something wild.

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  • Is TcpClient BeginRead/Send thread safe?

    - by wb
    Using a dotNET TcpClient if I have called an asynchronous BeginRead() on the associated network stream can I still call Write() on that stream on another thread? Or do I have to lock() the TcpClient in the code that is called back from the BeginRead and the code that does the send? Also if I close the TcpClient with: client.GetStream().Close(); client.Close(); Do I have to lock() on the TcpClient as well? Thanks in advance.

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  • How to efficiently save changes made in UI/main thread with Core Data?

    - by Jaanus
    So, there have been several posts here about importing and saving data from an external data source into Core Data. Apple documents a reasonable pattern for this: "import and save on background thread, merge saved objects to main thread." All fine and good. I have a related but different problem: the user is modifying data in the UI and main thread, and thus modifies state of some objects in the managed object context (MOC). I would like to save these changes from time to time. What is a good way to do that? Now, you could say that I could do the same: create a background thread with its own MOC and pass the changed objectID-s there. The catch-22 for me with this is that an object's ID changes when it is saved, and I cannot guarantee the order of things happening. I may end up passing a different objectID into the background thread for the same object, based on whether the object has been previously saved or not, and I don't know if Core Data can resolve this and see that different objectID-s are pointing to the same object and not create duplicates for me. (I could test this, but I'm lazywebbing with this question first.) One thought I had: I could always do MOC saves on a background thread, and queue them up with operationqueue, so that there is always only one save in progress. I would not create a new MOC, I would just use the same MOC as in main thread. Now, this is not thread safe and when someone modifies the MOC in main thread while it is being saved in background thread, the results will probably be catastrophic. But, minus the thread safety, you can see what kind of solution I'd wish for. To be clear, the problem I need to fix is that if I just do the save in main thread, it blocks the UI for an unacceptably long period of time, I want to move the save to background thread. So, questions: what about the reasoning of an object ID changing during saving, and Core Data being able to resolve them to the same object? Would this be the right way of addressing this problem? any other good ways of doing this?

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