[Libguestfs] [PATCH libguestfs 1/2] ocaml/implicit_close test: collect all currently unreachable blocks

[Richard W.M. Jones]

... And while I'm scrawling my throughts into this thread ...

What we intend here are two slightly different operations:

(A) Free every unreachable object.  That's what we want in this
specific place in the code.

(B) Provide a soft test that the OCaml heap hasn't been screwed
up because of bugs in our bindings.  That's what we use eg here:
https://gitlab.com/nbdkit/libnbd/-/blob/master/ocaml/tests/test_100_handle.ml#L24

In OCaml 4 Gc.compact provides (A) and (B), in particular compaction
is quite an aggressive & costly operation that requires examining and
moving every object on the heap.  In practice we found this quickly
reveals bugs in bindings.

OCaml 5 provides (A) through Gc.full_major--albeit not documented--and
doesn't seem to provide any way to do (B) as far as I can tell.

Rich.

-- 
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