[Bug debuginfod/28577] Make run-...-fd-prefetch-caches.sh test something

[Mark Wielaard]

Hi Noah,

On Mon, 2022-05-30 at 17:36 +0200, Mark Wielaard wrote:
> > Please find the new patch attached.
> 
> Thanks for adding all the comments. Looks good.

The only issue is that although it seems to work well on Fedora I am
having problems getting to test to work on an older CentOS 7 install.

It always seems to fail at this point:

 export DEBUGINFOD_URLS=http://127.0.0.1:$PORT1/
 # load prefetch cache with debuginfod-tars/usr/src/debug/hello.c
 testrun ${abs_top_builddir}/debuginfod/debuginfod-find debuginfo cee13b2ea505a7f37bd20d271c6bc7e5f8d2dfcb
 metrics=$(curl http://127.0.0.1:$PORT1/metrics)
 regex="fdcache_prefetch_count ([0-9])+"
 # Check to see if prefetch cache is maximally loaded. Note fdcache-prefetch (2) > prefetch-fds (1),
# so the debuginfod will try to load the prefetch cache with 2 files. We want prefetch-fds to cap that
# off
if [[ $metrics =~ $regex ]]; then
  if [[ ${BASH_REMATCH[1]} -ne $PREFETCH_FDS ]]; then
    err
  fi
else
  err
fi

Because I am getting:

++ curl http://127.0.0.1:8819/metrics
  % Total    % Received % Xferd  Average
Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left 
 Speed
^M  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:
--:--     0^M100  5793  100  5793    0     0  7532k      0 --:--:-- --
:--:-- --:--:-- 5657k
+ metrics='fdcache_bytes 0
fdcache_count 0
fdcache_op_count{op="emerg-flush"} 3
fdcache_op_count{op="enqueue"} 1
fdcache_op_count{op="evict"} 1
fdcache_op_count{op="prefetch_enqueue"} 1
fdcache_op_count{op="prefetch_evict"} 1
fdcache_op_count{op="probe_miss"} 2
fdcache_prefetch_bytes 0
fdcache_prefetch_count 0
[...]

So no bytes are prefetched at all.

I am not sure why this is happening. Do you see any obvious issue that
would explain this happening on centos7?

Thanks,

Mark