Re: newbie: VM asynchronous control from C Side
- From: Patrick Masotta <masottaus@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Sat, 23 Jun 2012 09:54:59 -0700 (PDT)
> There may be other options, but perhaps you could use the
> debug hooks for this (I'm making the assumption LuaJIT
> supports them completely...), particularly the "count"
> hook?
>
is there any document talking about LJ internals to read about them?
> This can give you a periodic call to your hook, though it
> won't actually return control back to the frame of the
> pcall.
this could be good for implementing a "pause"
> I would consider creating another thread to run
> the script, then using the hook (or coroutine) in
> association with a synchronisation semaphore/mutex/event to
> your main thread perhaps.
of course the VM will run on its own thread and the control will be done from
other thread... the usual multithread GUI-worker paradigm...
> There are some potential pitfalls though:
> * If you're allowing it to pause execution at arbitrary
> times during the script, the state of anything the script
> can access via FFI (or otherwise) is going to be
> undefined.
what do you mean with this? I just want to "pause", but I won't touch anything
while paused...
> Unless every single FFI call you provide is
> atomic, then it's going to get tricky. Either you
> can't do a lot on the main thread while the script is
> executing, or you're going to need to lock a lot of stuff;
> and that's going to open up a deadlock minefield if the
> script cannot complete while the main thread has paused it.
I just want the VM to "stop" execution w/o disturbing anything on VM's
thread...
> Explicit synchronisation, such as coroutines, would shift
> this burden onto the script,
no, no coroutines, the ones that will use this shouldn't have to deal with
coroutines at all, I have to do this entirely from C
> is writing these scripts (In my experience most end-users
> typically using Lua scripting in apps, tend to not
> understand threading and synchronisation issues, not really
> being programmers)
Sure .. I agree... that's why I want to hide the whole thing from LUA side
> * No matter what you do you're kind of limited to the
> "suspend" happening during Lua code. Any calls to FFI,
> or IO, or Lua API functions that may block (or simply take a
> long time) aren't going to get interrupted.
I know, but I can live with that.
I also need to know how to asynchronously force a clean "Abort"...
Let say the script is runing, the user closes the main C application;
how can I abort the VM leaking memory and things like that..
is it possible?
thanks
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