kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxxx>]

On Wed, Jan 20, 2016 at 11:58:56PM +0100, "Torsten Hüter" wrote:

> * It's very tricky to get stackful implementations to run stable. Any small fault results in a crash or deadlock.

What's strange in that? When doing pointers even small faults give you a crash (if you are lucky :D).

> * The most critical part is stack handling. For Windows Fibers / Pthreads the library does the job. There are also 
> some hacks to get Setjmp()/Longjmp() working with multiple stacks, as Jean-Pauls link has shown, I've tried it but that was crashing (Setjmp()/Longjmp() seems to be broken too on MinGW64).

longjmp is not guaranteed between 'contexts', so that would be expected too...

> * Side effects / show stoppers: It's not recommened to use threads for the wxWidgets GUI, OpenGL requires a context switch per thread.

Not a problem, we already declared that all the UI work is done in event handlers (as it should be)

> * As already known, Boost::Context is broken on Msys2 - makes it sense that such a low level library has to be maintained by KiCad developers (?)

Otherwise just hope that boost people fix that!

> * Is context switching always safe (side effects with 3rd party libraries / Python etc.)? 

Context as in thread usually yes, if you are not running concurrently... thread safety *usually* means proper locking of shared data structures

> Stackless coroutines:
> ---------------------
>
> * Relative easy to handle, because based on switch()/case().
> * Safer, a wrong state causes only the exit of the coroutine but not a crash.
> * Simple implementation

Simple?!? Well, maybe implementing but maintaining is another thing...

In my experience once you do the stack initialization correctly the
setjmp/longjmp is the 'best' coroutine you can do; the non-portable code
is relegated to the coroutine creation code so it's easily locked away
in some untouchable source file :P

OTOH I never did that on Win32/64 so maybe it's totally undependable to work :D
Isn't there some MSDN article on doing that?

-- 
Lorenzo Marcantonio
CZ Srl - Parma

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