tailscale/portlist/portlist.go
Brad Fitzpatrick 036f70b7b4 portlist: refactor, introduce OS-specific types
Add an osImpl interface that can be stateful and thus more efficient
between calls. It will later be implemented by all OSes but for now
this change only adds a Linux implementation.

Remove Port.inode. It was only used by Linux and moves into its osImpl.

Don't reopen /proc/net/* files on each run. Turns out you can just
keep then open and seek to the beginning and reread and the contents
are fresh.

    name                    old time/op    new time/op    delta
    GetListIncremental-8    7.29ms ± 2%    6.53ms ± 1%  -10.50%  (p=0.000 n=9+9)

    name                   old alloc/op   new alloc/op   delta
    GetListIncremental-8    1.30kB ±13%    0.70kB ± 5%  -46.38%  (p=0.000 n=9+10)

    name                  old allocs/op  new allocs/op  delta
    GetListIncremental-8      33.2 ±11%      18.0 ± 0%  -45.82%  (p=0.000 n=9+10)

Updates #5958

Change-Id: I4be83463cbd23c2e2fa5d0bdf38560004f53401b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2022-10-23 20:29:23 -07:00

82 lines
1.7 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file is just the types. The bulk of the code is in poller.go.
// The portlist package contains code that checks what ports are open and
// listening on the current machine.
package portlist
import (
"fmt"
"sort"
"strings"
)
// Port is a listening port on the machine.
type Port struct {
Proto string // "tcp" or "udp"
Port uint16 // port number
Process string // optional process name, if found
}
// List is a list of Ports.
type List []Port
func (a *Port) lessThan(b *Port) bool {
if a.Port != b.Port {
return a.Port < b.Port
}
if a.Proto != b.Proto {
return a.Proto < b.Proto
}
return a.Process < b.Process
}
func (a *Port) equal(b *Port) bool {
return a.Port == b.Port &&
a.Proto == b.Proto &&
a.Process == b.Process
}
func (a List) equal(b List) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if !a[i].equal(&b[i]) {
return false
}
}
return true
}
func (pl List) String() string {
var sb strings.Builder
for _, v := range pl {
fmt.Fprintf(&sb, "%-3s %5d %#v\n",
v.Proto, v.Port, v.Process)
}
return strings.TrimRight(sb.String(), "\n")
}
// sortAndDedup sorts ps in place (by Port.lessThan) and then returns
// a subset of it with duplicate (Proto, Port) removed.
func sortAndDedup(ps List) List {
sort.Slice(ps, func(i, j int) bool {
return (&ps[i]).lessThan(&ps[j])
})
out := ps[:0]
var last Port
for _, p := range ps {
protoPort := Port{Proto: p.Proto, Port: p.Port}
if last == protoPort {
continue
}
out = append(out, p)
last = protoPort
}
return out
}