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Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (11 Nov 2022 17:19 UTC)
Re: Recent additions/changes (see personal repo) Shiro Kawai (14 Nov 2022 19:05 UTC)
Re: Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (14 Nov 2022 19:11 UTC)
Re: Recent additions/changes (see personal repo) Shiro Kawai (15 Nov 2022 08:31 UTC)
Re: Recent additions/changes (see personal repo) Marc Feeley (17 Nov 2022 13:22 UTC)
Re: Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (17 Nov 2022 13:51 UTC)
Re: Recent additions/changes (see personal repo) Marc Feeley (17 Nov 2022 14:24 UTC)
Re: Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (17 Nov 2022 14:44 UTC)
Re: Recent additions/changes (see personal repo) Marc Feeley (17 Nov 2022 15:38 UTC)
Re: Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (17 Nov 2022 16:26 UTC)
Re: Recent additions/changes (see personal repo) Shiro Kawai (17 Nov 2022 20:12 UTC)
Re: Recent additions/changes (see personal repo) Marc Nieper-Wißkirchen (17 Nov 2022 20:32 UTC)
Re: Recent additions/changes (see personal repo) Shiro Kawai (17 Nov 2022 23:02 UTC)
Re: Recent additions/changes (see personal repo) Shiro Kawai (17 Nov 2022 23:13 UTC)
Re: Recent additions/changes (see personal repo) Marc Feeley (17 Nov 2022 20:43 UTC)
Re: Recent additions/changes (see personal repo) Marc Feeley 17 Nov 2022 20:43 UTC 
> On Nov 17, 2022, at 3:12 PM, Shiro Kawai <xxxxxx@gmail.com> wrote:
>
> On Thu, Nov 17, 2022 at 6:26 AM Marc Nieper-Wißkirchen <xxxxxx@gmail.com> wrote:
>
> The problem is that the interrupting thread and the interrupted thread
> won't be synchronized.  We can only say that the interrupted thread
> must eventually observe the interrupt.  But this is probably enough,
> so we should add something along the following lines:
>
> The interrupt must be handled eventually as long as the union of
> intervals in which the interrupted thread has interrupts enabled is
> unbounded.  (This is some kind of a rewrite of your "bounded"
> condition.)
>
>
> So are you going to change the spec that the interrupt  is 'queued' if the current-interrupt-level > 0, and handled after current-interrupt-level drops to 0?  (I think that's the right thing.)
>
> Another concern is that how interrupt thunk is scheduled if it occurs during executing another interrupt thunk.  Suppose two interrupt occurs in this chronological order:
>
>   1:  (thread-interrupt! T (lambda () (do-X))
>   2:  (thread-interrupt! T (lambda () (do-Y))
>
> If 2 occurs when T is start executing 1's thunk, but before doing actual work (do-X), does the second thunk is run before (do-X), or it is scheduled after the whole (lambda () (do-X)) thunk?
>
> If it's the former case, we might want to disable interrupts automatically before executing an interrupt thunk, much like a signal is blocked automatically in a signal handler in Unix.  Combined with the queued handler model, the inversion of the order may be an issue; that is, thread Tdisables interrupts, another thread interrupts T with do-X, and after a certain time, T enables interrupts.  Then (lambda () (do-X)) start to run, but suppose another thread inerrupts T right before (do-X) is called.   Even the first interrupt occurs long before the second, (do-Y) is executed first unexpectedly.

The order in which interrupts are handled by the target thread should not be guaranteed.  The only guarantee should be that the thunk will start executing after a finite time after the target thread’s interrupt level goes to 0.

Another option (if some ordering must be guaranteed) is to give priority to the most recent interrupts.  This can be done by using a LIFO structure for pending interrupts rather than a FIFO.

Automatically disabling interrupts when a thunk starts executing does not solve any problems that can’t be solved by writing the thunk as (lambda () (with-interrupts-disabled <body>)) if that is relevant.  A common use of timer interrupts is to do preemptive task scheduling and this would become harder to implement if interrupts are automatically disabled.

Marc