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[Solved] Why Qt has so limited synchronization possibilities comparing with WinAPI?
I started to check QThread, QWaitCondition, QMutex classes. And, in my opinion, they haven't some very useful possibilities, which are under Windows:
WaitForMultipleObjects - where I can wait one only kernel object from several, not all of them;
Check Wait... function for WAIT_ABANDONED - not to lock waiting thread if master (current owner of the mutex) died, but did not release mutex;
CreateEvent - event objects are very good for cross-synchronization with exact thread sequence. And named kernel objects - not to launch second instance of app.
Access to thread, process handles - to wait untill they finished theyr job..
Why all of them are not implemented?
Or these functionalities are hidden in another classes?
There are many more classes than that. See "Thread Support in Qt":http://doc-snapshot.qt-project.org/qt5-stable/threads.html for a list of all available classes. See "Multithreading Technologies in Qt":http://doc-snapshot.qt-project.org/qt5-stable/threads-technologies.html for an overview of different ways to use threads.
Also, remember that Qt is a cross-platform framework. It provides high-level APIs, not low-level kernel accessors.
[quote]WaitForMultipleObjects – where I can wait one only kernel object from several, not all of them;[/quote]See QFutureSynchronizer.
[quote]Check Wait… function for WAIT_ABANDONED – not to lock waiting thread if master (current owner of the mutex) died, but did not release mutex;[/quote]If a program produces abandoned mutexes, then the program is broken. That's why AbandonedMutexException exists -- abandoned mutexes are exceptions (errors).
Use QMutexLocker instead. It will guarantee that a mutex is released when a thread dies.
[quote]CreateEvent – event objects are very good for cross-synchronization with exact thread sequence.[/quote]Qt is an event-driven framework and uses events are everywhere. First, read about "Signals and Slots":http://qt-project.org/doc/qt-5.1/qtcore/signalsandslots.html, which extend the event system. Then, read about "how to use the event system for inter-thread communication":http://doc-snapshot.qt-project.org/qt5-stable/threads-synchronizing.html#high-level-event-queues.
[quote]And named kernel objects – not to launch second instance of app.[/quote]Yes, that would be a nice feature. It's unrelated to synchronization/multithreading though.
[quote]Access to thread, process handles – to wait untill they finished theyr job[/quote]
By the way, you talked about waiting a lot. If you are designing a new program, I encourage you to start using signals and slots. This is taken from the QThread documentation:
"Note: wait() and the sleep() functions should be unnecessary in general, since Qt is an event-driven framework. Instead of wait(), consider listening for the finished() signal. Instead of the sleep() functions, consider using QTimer."
[quote]Why all of them are not implemented?[/quote]Please read the documentation carefully before declaring that functions aren't implemented and the framework is limited.
@JKSH -Thanks for mentioned classes and links. But...
[quote] Please read the documentation carefully before declaring that functions aren't implemented and the framework is limited.[/quote]
There is no need to be so rude... In my post there are no insults in address of Qt. Look at a title - It is a question, not a statement. And after reading carefully documentation during several hours, and looking for info in forum posts all evening, I think I have a right to ask something. A couple years ago I worked in a company where we used our own thread library. And I was responsible for it architecture and several classes. And in analogy I looked for mentioned functionality in Qt classes, which, I think, should have it.
At the end of my post I sincerely asked: "Or these functionalities are hidden in another classes? ". Qt, C#, Java have a lot of classes, and to read, try and understand them there is a need for much bigger free time. In a production, as you know, it is a luxury. After working a lot of time in one language or lib, and switching on another - the most common question - "Where did they hide all this stuff?"
So, please, try to respect newcommers to Qt, and be a little more polite.
I'm sorry for being rude, and for ignoring your last question. Thank you for explaining your background. You're right: free time is a luxury, so it was unfair of me to expect you to find all the information beforehand.
Your questions were "loaded questions":http://en.wikipedia.org/wiki/Loaded_question, however: "Why Qt has so limited synchronization possibilities?" and "Why all of them are not implemented?" have very different meanings from "Where did they hide all this stuff?". I made my last statement because I assumed that you were trying to hide statements inside loaded questions (which is done often, and it's considered a logical fallacy), but that was an unfair assumption too. Again, I apologize.
Let's start over.
Welcome to the Qt community. I hope that you find Qt useful in your projects. If you have any questions, feel free to ask and I'm sure someone here will be happy to help you out!
In turn, I must admit, that my question should be sound more like "Where did they hide all this stuff?". I my another post <Exception at ... code: 0xc0000138> you are helping me a lot. Thanks!!!
And I hope, I could help you in some field too. :-)