This was the proximate cause of #2579.
#2582 is a deeper fix, but this will remain
as a footgun, so may as well fix it too.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This is a simplified rate limiter geared for exactly our needs:
A fast, mono.Time-based rate limiter for use in tstun.
It was generated by stripping down the x/time/rate rate limiter
to just our needs and switching it to use mono.Time.
It removes one time.Now call per packet.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Package mono provides a fast monotonic time.
Its primary advantage is that it is fast:
It is approximately twice as fast as time.Now.
This is because time.Now uses two clock calls,
one for wall time and one for monotonic time.
We ask for the current time 4-6 times per network packet.
At ~50ns per call to time.Now, that's enough to show
up in CPU profiles.
Package mono is a first step towards addressing that.
It is designed to be a near drop-in replacement for package time.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Makes parsing 4.6x faster.
name old time/op new time/op delta
ParseInt-12 32.1ns ± 1% 6.9ns ± 2% -78.55% (p=0.000 n=10+9)
Signed-off-by: David Anderson <danderson@tailscale.com>
Go's time.Parse always allocates a FixedZone for time strings not in
UTC (ending in "Z"). This avoids that allocation, at the cost of
adding a cache.
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
