On Mon, Sep 05, 2022 at 02:10:36PM +0200, Laszlo Ersek wrote:
> On 09/03/22 00:14, Eric Blake wrote:
> > This proves that the stat counters increment as desired, as well as
> > proving that our RUInt32 generator type works.
>
> How is this related to RUint32?
Typo in the commit message; this should be RUInt64. Oh well, the
commit is already in.
>
> >
> > This commit is also a showcase of whether I can do 64-bit math in
> > various languages (C's terseness in 'a == b + (c > d)' is annoying to
> > replicate in languages that don't like playing fast and loose with
> > types). :)
>
> I don't understand; please elaborate.
Sure. In C, uint64_t == uint64_t + bool is legal; making for a nice
terse expression.
> > +++ b/python/t/620-stats.py
> > +# Stats are still readable after the connection closes; we don't know if
> > +# the server sent reply bytes to our NBD_CMD_DISC, so don't insist on it.
> > +h.shutdown()
> > +
> > +bs3 = h.stats_bytes_sent()
> > +cs3 = h.stats_chunks_sent()
> > +br3 = h.stats_bytes_received()
> > +cr3 = h.stats_chunks_received()
> > +
> > +assert bs3 > bs2
> > +assert cs3 == cs2 + 1
> > +assert br3 >= br2
> > +assert cr3 == cr2 + (br3 > br2)
And in python.
> > +++ b/ocaml/tests/test_620_stats.ml
> > + (* Stats are still readable after the connection closes; we don't know if
> > + * the server sent reply bytes to our NBD_CMD_DISC, so don't insist on
> > it.
> > + *)
> > + NBD.shutdown nbd;
> > +
> > + let bs3 = NBD.stats_bytes_sent nbd in
> > + let cs3 = NBD.stats_chunks_sent nbd in
> > + let br3 = NBD.stats_bytes_received nbd in
> > + let cr3 = NBD.stats_chunks_received nbd in
> > + let fudge = if cr2 = cr3 then 0L else 1L in
> > + assert (bs3 > bs2);
> > + assert (cs3 = (Int64.succ cs2));
> > + assert (br3 >= br2);
> > + assert (cr3 = (Int64.add cr2 fudge))
Not so in OCaml, where + isn't even polymorphic to int64, so I have to
break out manual calls to Int64.XXX methods. Here, I went with a
helper variable 'fudge'.
> > +++ b/golang/libnbd_620_stats.go
> > + /* Stats are still readable after the connection closes; we don't know
> > if
> > + * the server sent reply bytes to our NBD_CMD_DISC, so don't insist on
> > it.
> > + */
> > + err = h.Shutdown(nil)
> > + if err != nil {
> > + t.Fatalf("%s", err)
> > + }
> > +
> > + bs3, err := h.StatsBytesSent()
> > + if err != nil {
> > + t.Fatalf("%s", err)
> > + }
> > + cs3, err := h.StatsChunksSent()
> > + if err != nil {
> > + t.Fatalf("%s", err)
> > + }
> > + br3, err := h.StatsBytesReceived()
> > + if err != nil {
> > + t.Fatalf("%s", err)
> > + }
> > + cr3, err := h.StatsChunksReceived()
> > + if err != nil {
> > + t.Fatalf("%s", err)
> > + }
> > + slop := uint64(1)
> > + if br2 == br3 {
> > + slop = uint64(0)
> > + }
> > +
> > + if bs3 <= bs2 {
> > + t.Fatalf("unexpected value for bs3")
> > + }
> > + if cs3 != cs2 + 1 {
> > + t.Fatalf("unexpected value for cs3")
> > + }
> > + if br3 < br2 {
> > + t.Fatalf("unexpected value for br3")
> > + }
> > + if cr3 != cr2 + slop {
> > + t.Fatalf("unexpected value for cr3")
> > + }
Nor in Go, where you can't even do uint64(bool), but HAVE to use an
'if' statement to populate 'slop' with the correct value. Hmm, maybe
I should have used the same variable name between OCaml and Go,
instead of 'slop'/'fudge'; oh well. (And Go is painfully verbose in
the amount of boilerplate formatting it requires, compared to the
other languages; although I will be the first to admit that I'm
probably not an idiomatic Go coder)
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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