----- Original Message ----- From: "Oliver Kowalke" <k-oli@gmx.de> To: <boost@lists.boost.org> Sent: Saturday, January 15, 2011 8:38 PM Subject: Re: [boost] [context] new version - support for Win64
Am 15.01.2011 19:02, schrieb vicente.botet:
* The sentence in the Overview "(threads are preemptively scheduled)" could be misleading as the code will in any case be run on a thread.
threads are scheduled by the operating system - the scheduling is pre-emptive - the code can be suspended at (almost) any time. The sentence should express the difference to userland-threads/fibers/lightweight-threads (etc.) where each context decides when it get suspended(cooperative scheduling). off curse the context is running in one thread it will be pre-emptively suspended by the os scheduler.
I understand. I was just only telling that the sentence was misleading and maybe you can change it.
* How is this related to setjmp/longjmp?
::longjmp() is not required to preserve the stack frame - so jumping back to a function which was exited via ::longjump() is undefined
Maybe it is worh to add something in the documentation explaining the advantages.
* How exceptions are propagated when calling to jump_to()?
context::jump_to() doesn't throw. as noted in the docu the code jumped into via context::jump_to() must not throw
I don't see it on the reference part. Could you point me where it is documented? So if exceptions can not be propagated between contexts, how the user does with exceptions?
* Why do you need a ::create function?
to have a named ctor - default ctor creates an 'not_a_context'. This is required by the move semantics
This don't answer my question. Why you don't provide a constructor with the same parameters ::create has?
* Could you clarify your sentence "Frame-unwind-tables instead of setjmp/longjmp based exception handling must be used in order to catch exception inside called function."
for instance gcc supports both strategies how exceptions are modelled/propagated. calling ::longjmp() is equivalent to throw statement. Functions written in C++ will have unwind information by default.
And how this translates to the user? Do the user needs to do someting specific?
* Performances comparison between fiber and fcontext will be welcome
do refer to boost.fiber? boost.fiber uses boost.context internally. fcontext is an implementation detail of boost.context. I don't understand the need for comparing it.
No I mean comparaison between yous specific implementation with assembler and the use of Windows Fibers to implement Boost.Context. That is the same kind of comparison you did for UNIX. Sorry if I was not enough clear. Vicente