tailscale/wgengine
Brad Fitzpatrick 6aa10576c9 wgengine/magicsock: deflake TestTwoDevicePing compare-metrics-stats
The compare-metrics-stats subtest reset two independent counting
systems (physical connection counters and expvar.Int user metrics)
non-atomically. Background WireGuard keepalives arriving between the
resets could increment one system but not the other, causing
off-by-one packet/byte mismatches in either direction.

Replace the reset-then-compare pattern with snapshot-and-delta:
snapshot both systems before pings, snapshot again after, and compare
the deltas. This eliminates the non-atomic reset window entirely.
As a belt-and-suspenders safety net, tolerate a difference of exactly
one packet (and corresponding bytes) from a stray keepalive that
could still arrive in the narrow window between the two snapshots.

flakestress passes with ~5900 runs (~2800 without -race, ~3100 with
-race) but it also passed previously too. This is an annoying one to
repro.

Fixes #11762

Change-Id: I3447ad67e71c8146e85eed38b7a665033ef9e284
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-14 06:57:24 -07:00
..
bench all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
filter all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
magicsock wgengine/magicsock: deflake TestTwoDevicePing compare-metrics-stats 2026-04-14 06:57:24 -07:00
netlog all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netstack all: fix six tests that failed with -count=2 2026-04-13 18:52:57 -07:00
router wgengine/router/osrouter: fix privileged tests missing fake netfilter runner 2026-04-10 14:51:55 -07:00
wgcfg cmd/vet: add subtestnames analyzer; fix all existing violations 2026-04-05 15:52:51 -07:00
wgint all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
wglog all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
winnet all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
mem_ios.go all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
pendopen_omit.go all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
pendopen.go all: use bart.Lite instead of bart.Table where appropriate 2026-03-24 14:45:23 +00:00
userspace_ext_test.go all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
userspace_test.go wgengine/userspace: add extra check for tsmp learned keys in engine (#19223) 2026-04-07 09:11:11 -04:00
userspace.go tsd, all: add Sys.ExtraRootCAs, plumb through TLS dial paths 2026-04-07 18:10:54 -07:00
watchdog_omit.go all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
watchdog_test.go cmd/vet: add subtestnames analyzer; fix all existing violations 2026-04-05 15:52:51 -07:00
watchdog.go control/controlclient,ipn/ipnlocal,wgengine: avoid restarting wireguard when key is learned via tsmp (#19142) 2026-03-30 14:26:08 -04:00
wgengine.go all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00