[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [Qemu-block] [PATCH 3/5] coroutines: abort if we try to

From: Stefan Hajnoczi
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 3/5] coroutines: abort if we try to enter a still-sleeping coroutine
Date: Mon, 20 Nov 2017 11:43:34 +0000
User-agent: Mutt/1.9.1 (2017-09-22)

On Sun, Nov 19, 2017 at 09:46:44PM -0500, Jeff Cody wrote:
> diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h
> index 931cdc9..b071217 100644
> --- a/include/qemu/coroutine_int.h
> +++ b/include/qemu/coroutine_int.h
> @@ -56,6 +56,8 @@ struct Coroutine {
>      int scheduled;
> +    int sleeping;


BTW an alternative to adding individual bools is to implement a finite
state machine for the entire coroutine lifecycle.  A single function can
validate all state transitions:

  void check_state_transition(CoState old, CoState new,
                              const char *action)
      const char *errmsg = fsm[old][new];
      if (!errmsg) {
          return; /* valid transition! */

      fprintf(stderr, "Cannot %s coroutine from %s state\n",
              action, state_name[old]);

Specifying fsm[][] forces us to think through all possible state
transitions.  This approach is proactive whereas adding bool flags is
reactive since it only covers a subset of states that were encountered
after crashes.  I'm not sure if it's worth it though :).

Attachment: signature.asc
Description: PGP signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]