bug#43565: cuirass: Fibers scheduling blocked.

[Mathieu Othacehe]

Hey,

> In cuirass/utils.scm:
>    320:22  1 (_)
> In unknown file:
>            0 (make-stack #t)
> ERROR: In procedure make-stack:
> In procedure struct-vtable: Wrong type argument in position 1 (expecting 
> struct): #f

I think this error is caused by setting:

--8<---------------cut here---------------start------------->8---
  ;; STORE's socket is O_NONBLOCK but since we're
  ;; not in a fiber, disable Fiber's handlers.
  (current-read-waiter #f)
  (current-write-waiter #f)
--8<---------------cut here---------------end--------------->8---

where it should be:

--8<---------------cut here---------------start------------->8---
  ;; STORE's socket is O_NONBLOCK but since we're
  ;; not in a fiber, disable Fiber's handlers.
  (current-read-waiter
   (lambda (port)
     (port-poll port "r")))
  (current-write-waiter
   (lambda (port)
     (port-poll port "w")))
--8<---------------cut here---------------end--------------->8---

then this should also be done in "fetch-inputs" that is using non
blocking ports outside of Fibers.

However, I still have the following error:

--8<---------------cut here---------------start------------->8---
In ice-9/boot-9.scm:
  1731:15 17 (with-exception-handler #<procedure 7fac67194000 at ic…> …)
  1736:10 16 (with-exception-handler _ _ #:unwind? _ # _)
In ice-9/eval.scm:
    619:8 15 (_ #(#(#(#(#<directory (cuirass base) 7fac6b51c…>)) …) …))
In unknown file:
          14 (_ #<procedure 7fac69b10b20 at ice-9/eval.scm:330:13 ()> …)
          13 (partition #<procedure 7fac69b10880 at ice-9/eval.scm:…> …)
In guix/store.scm:
   1008:0 12 (valid-path? #<store-connection 256.99 7fac6b3fd6e0> "/…")
2020-11-19T11:47:23 Failed to compute metric average-eval-build-start-time (1).
   717:11 11 (process-stderr #<store-connection 256.99 7fac6b3fd6e0> _)
In guix/serialization.scm:
    76:12 10 (read-int #<input-output: socket 49>)
In ice-9/suspendable-ports.scm:
   307:17  9 (get-bytevector-n #<input-output: socket 49> 8)
2020-11-19T11:47:23 Failed to compute metric average-eval-build-complete-time 
(1).
2020-11-19T11:47:23 Failed to compute metric evaluation-completion-speed (1).
   284:18  8 (get-bytevector-n! #<input-output: socket 49> #vu8(0 …) …)
    67:33  7 (read-bytes #<input-output: socket 49> #vu8(0 0 0 0 0 …) …)
In fibers/internal.scm:
    402:6  6 (suspend-current-fiber _)
In ice-9/boot-9.scm:
  1669:16  5 (raise-exception _ #:continuable? _)
  1764:13  4 (_ #<&compound-exception components: (#<&error> #<&orig…>)
In cuirass/utils.scm:
    319:8  3 (_ _ . _)
In ice-9/boot-9.scm:
  1731:15  2 (with-exception-handler #<procedure 7fac683ea300 at ic…> …)
In cuirass/utils.scm:
   320:22  1 (_)
In unknown file:
           0 (make-stack #t)
ERROR: In procedure make-stack:
Attempt to suspend fiber within continuation barrier
--8<---------------cut here---------------end--------------->8---

that originates from "valid-path?" in "restart-builds", not sure how to
fix it yet.

Thanks,

Mathieu