util/dirwalk, metrics, portlist: add new package for fast directory walking

This is similar to the golang.org/x/tools/internal/fastwalk I'd
previously written but not recursive and using mem.RO.

The metrics package already had some Linux-specific directory reading
code in it. Move that out to a new general package that can be reused
by portlist too, which helps its scanning of all /proc files:

    name                old time/op    new time/op    delta
    FindProcessNames-8    2.79ms ± 6%    2.45ms ± 7%  -12.11%  (p=0.000 n=10+10)

    name                old alloc/op   new alloc/op   delta
    FindProcessNames-8    62.9kB ± 0%    33.5kB ± 0%  -46.76%  (p=0.000 n=9+10)

    name                old allocs/op  new allocs/op  delta
    FindProcessNames-8     2.25k ± 0%     0.38k ± 0%  -82.98%  (p=0.000 n=9+10)

Change-Id: I75db393032c328f12d95c39f71c9742c375f207a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2022-11-05 14:26:29 -07:00
committed by Brad Fitzpatrick
parent 21ef7e5c35
commit db2cc393af
9 changed files with 422 additions and 178 deletions

View File

@@ -34,7 +34,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
tailscale.com/hostinfo from tailscale.com/net/interfaces+
tailscale.com/ipn from tailscale.com/client/tailscale
tailscale.com/ipn/ipnstate from tailscale.com/client/tailscale+
💣 tailscale.com/metrics from tailscale.com/cmd/derper+
tailscale.com/metrics from tailscale.com/cmd/derper+
tailscale.com/net/dnscache from tailscale.com/derp/derphttp
tailscale.com/net/flowtrack from tailscale.com/net/packet+
💣 tailscale.com/net/interfaces from tailscale.com/net/netns+
@@ -72,6 +72,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
W tailscale.com/util/clientmetric from tailscale.com/net/tshttpproxy
tailscale.com/util/cloudenv from tailscale.com/hostinfo+
W tailscale.com/util/cmpver from tailscale.com/net/tshttpproxy
L 💣 tailscale.com/util/dirwalk from tailscale.com/metrics
tailscale.com/util/dnsname from tailscale.com/hostinfo+
W tailscale.com/util/endian from tailscale.com/net/netns
tailscale.com/util/lineread from tailscale.com/hostinfo+