> > First of all, let me describe my task to make it > > easier for you to understand what I need. I am trying to make a > > multithreaded text editor. > > To what end? In most cases, manipulation of text is "easy enough" that a si= > ngle thread can support multiple views into the same buffer - indeed you ca= > n easily make an editor based on Fl_Text_Buffer and Fl_Text_Editor that mai= > ntains multiple views into the same text buffer in separate windows. > Though whether it is a good idea to do that or not I'm not sure...! (I'm no= > t sure how safe the Fl_Text_Buffer implementation is if used like that, tho= > ugh I have actually done it...) > > Creating a multi-threaded tool to do this may be a lot of work, so you'd re= > ally need to be sure you needed it! > > > > Firstly I thought to make full process of > > redrawing of each window of the editor multi threaded, but as I > > understood from your arguments it's impossible because of graphics card > > restrictions. > > Not impossible. But tricky to do safely and robustly. > Threads can be quite "difficult"... > > > So my aim now is to make functionality of this windows > > multithreaded. All process of work with text editor is based on work > > with text buffer ( which in my design is unique for each window) and > > reacting on buttons callbacks like copy, open,etc. So, now my questions > > are: > > 1) Is it possible to make callback functions multithreaded? Maybe you > > can give some example? > > Not sure what you are asking here. > Are you asking about putting the functionality of the callbacks, into separ= > ate threads? > > As a general rule, callbacks need to run in the context of the main() threa= > d, and they really want to return as soon as possible. > > If you want to perform some long lived action, triggered by a callback, the= > n it is best *not* to perform that action in the context of the callback at= > all. You can have the callback spawn a worker thread and return immediatel= > y, then reap the results of that worker thread at some later time, e.g. via= > an Fl::awake() call or a timer or some such... > > Is that what you mean? > > > 2) The "lags"(long-term operations) in my program are unexpected by > > design so I don't know in which place to make FL::awake() to give > > control back to main thread. > > Um, that's not really the way it works. You call Fl::awake() from your work= > er thread any time you have changed something that you want the main thread= > to display. > You do not give control "back to the main thread", since all threads run at= > the same time, in parallel. = > > > > So I guess I need to combine multi > > threading with timer callbacks mechanism. Like "if window not > > responding for 2 sec, give control to another thread, while operation > > is still in progress". > > Again, that's not really the way it works - all the threads run at the same= > time, you don't really choose which runs when, so there is no scope to "gi= > ve control to another thread" per se. > > > The main idea is that you work in one window > > while some operation continues in another one. What are your > > ideas/experience about these? Maybe some example? So far, if i do some > > long-time loop in one of the window's callback function another just > > stops as well. > > Never do long operation in a callback, as that will stall the fltk loop. Al= > ways do long operations outside the fltk context (e.g. in a worker thread) = > or contrive for your long operation to call Fl::check() quite often... > > > > 3)How can I pass control back to child's thread from main thread? For > > example I made fl::awake() during some long-term operation,because user > > started input in other window but i need that operation to be done till > > end, so when user stopped input i want main thread to "return" to that > > position in child's thread where it was left. > > It sounds like you have misunderstood what Fl::awake() does... > > > P.S. I I know that most of this things can be done ( and possibly > > easier) single threaded , but multiple threads is a must for this > > project. Thanks for your fast and informative response. > > I'm not sure how much experience you have of using threads, but it does not= > sound like you are that familiar with the techniques involved. You probabl= > y need to spend a little time getting more familiar with how threads work a= > nd how to make multi-threaded programs, as that foundation will make your p= > roject much more robust. Multi-threading is complicated to do well with cur= > rent C/C++ tools, and very easy to get wrong (in confusing and herd-to-debu= > g ways!) > > I'm not sure how to describe to you, how to make these things work, as I'm = > not sure how much understanding you have of the issues surrounding threadin= > g. What is your background in multi-threading? We can maybe build up from t= > here? > > > > > Selex ES Ltd > Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS= > 14 3EL > A company registered in England & Wales. Company no. 02426132 > ******************************************************************** > This email and any attachments are confidential to the intended > recipient and may also be privileged. If you are not the intended > recipient please delete it from your system and notify the sender. > You should not copy it or use it for any purpose nor disclose or > distribute its contents to any other person. > ******************************************************************** > Thanks again for useful answer. Yea I just misunderstood the meaning of FL::awake function,sorry. My background in multithreading is not bad i guess, (C++ boost library threads, pthreads,C# threads, Java threads,OpenMp, MPI), but I am very new to FLTK, so it's hard for me to combine multithreading and FLTK mechanisms so far. But,you know, your answers were really informative and now I understand the problem and possible solutions better. I know that multithreading is hard as hell in most times, but I think I'll get through. Thanks again, maybe some more questions will arrive later. _______________________________________________ fltk mailing list fltk@easysw.com http://lists.easysw.com/mailman/listinfo/fltk
