util/uniq,types/lazy,*: delete code that's now in Go std

sync.OnceValue and slices.Compact were both added in Go 1.21.

cmp.Or was added in Go 1.22.

Updates #8632
Updates #11058

Change-Id: I89ba4c404f40188e1f8a9566c8aaa049be377754
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/k8s-operator/depaware.txt

@@ -817,7 +817,6 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+
         tailscale.com/util/testenv                                   from tailscale.com/control/controlclient+
         tailscale.com/util/truncate                                  from tailscale.com/logtail
-        tailscale.com/util/uniq                                      from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/usermetric                                from tailscale.com/health+
         tailscale.com/util/vizerror                                  from tailscale.com/tailcfg+
      💣 tailscale.com/util/winutil                                   from tailscale.com/clientupdate+

cmd/tailscaled/depaware.txt

@@ -406,7 +406,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+
         tailscale.com/util/testenv                                   from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/truncate                                  from tailscale.com/logtail
-        tailscale.com/util/uniq                                      from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/usermetric                                from tailscale.com/health+
         tailscale.com/util/vizerror                                  from tailscale.com/tailcfg+
      💣 tailscale.com/util/winutil                                   from tailscale.com/clientupdate+

ipn/ipnlocal/local.go

@@ -111,7 +111,6 @@ import (
 	"tailscale.com/util/syspolicy/rsop"
 	"tailscale.com/util/systemd"
 	"tailscale.com/util/testenv"
-	"tailscale.com/util/uniq"
 	"tailscale.com/util/usermetric"
 	"tailscale.com/version"
 	"tailscale.com/version/distro"
@@ -3346,7 +3345,7 @@ func (b *LocalBackend) clearMachineKeyLocked() error {
 // incoming packet.
 func (b *LocalBackend) setTCPPortsIntercepted(ports []uint16) {
 	slices.Sort(ports)
-	uniq.ModifySlice(&ports)
+	ports = slices.Compact(ports)
 	var f func(uint16) bool
 	switch len(ports) {
 	case 0:

ipn/localapi/debugderp.go

@@ -4,6 +4,7 @@
 package localapi
 
 import (
+	"cmp"
 	"context"
 	"crypto/tls"
 	"encoding/json"
@@ -81,7 +82,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 		client *http.Client = http.DefaultClient
 	)
 	checkConn := func(derpNode *tailcfg.DERPNode) bool {
-		port := firstNonzero(derpNode.DERPPort, 443)
+		port := cmp.Or(derpNode.DERPPort, 443)
 
 		var (
 			hasIPv4 bool
@@ -89,7 +90,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 		)
 
 		// Check IPv4 first
-		addr := net.JoinHostPort(firstNonzero(derpNode.IPv4, derpNode.HostName), strconv.Itoa(port))
+		addr := net.JoinHostPort(cmp.Or(derpNode.IPv4, derpNode.HostName), strconv.Itoa(port))
 		conn, err := dialer.DialContext(ctx, "tcp4", addr)
 		if err != nil {
 			st.Errors = append(st.Errors, fmt.Sprintf("Error connecting to node %q @ %q over IPv4: %v", derpNode.HostName, addr, err))
@@ -98,7 +99,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 
 			// Upgrade to TLS and verify that works properly.
 			tlsConn := tls.Client(conn, &tls.Config{
-				ServerName: firstNonzero(derpNode.CertName, derpNode.HostName),
+				ServerName: cmp.Or(derpNode.CertName, derpNode.HostName),
 			})
 			if err := tlsConn.HandshakeContext(ctx); err != nil {
 				st.Errors = append(st.Errors, fmt.Sprintf("Error upgrading connection to node %q @ %q to TLS over IPv4: %v", derpNode.HostName, addr, err))
@@ -108,7 +109,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// Check IPv6
-		addr = net.JoinHostPort(firstNonzero(derpNode.IPv6, derpNode.HostName), strconv.Itoa(port))
+		addr = net.JoinHostPort(cmp.Or(derpNode.IPv6, derpNode.HostName), strconv.Itoa(port))
 		conn, err = dialer.DialContext(ctx, "tcp6", addr)
 		if err != nil {
 			st.Errors = append(st.Errors, fmt.Sprintf("Error connecting to node %q @ %q over IPv6: %v", derpNode.HostName, addr, err))
@@ -117,7 +118,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 
 			// Upgrade to TLS and verify that works properly.
 			tlsConn := tls.Client(conn, &tls.Config{
-				ServerName: firstNonzero(derpNode.CertName, derpNode.HostName),
+				ServerName: cmp.Or(derpNode.CertName, derpNode.HostName),
 				// TODO(andrew-d): we should print more
 				// detailed failure information on if/why TLS
 				// verification fails
@@ -166,7 +167,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 			addr = addrs[0]
 		}
 
-		addrPort := netip.AddrPortFrom(addr, uint16(firstNonzero(derpNode.STUNPort, 3478)))
+		addrPort := netip.AddrPortFrom(addr, uint16(cmp.Or(derpNode.STUNPort, 3478)))
 
 		txID := stun.NewTxID()
 		req := stun.Request(txID)
@@ -292,13 +293,3 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 	//   issued in the first place, tell them specifically that the
 	// 	 cert is bad not just that the connection failed.
 }
-
-func firstNonzero[T comparable](items ...T) T {
-	var zero T
-	for _, item := range items {
-		if item != zero {
-			return item
-		}
-	}
-	return zero
-}

types/lazy/lazy.go

@@ -120,41 +120,6 @@ func (z *SyncValue[T]) PeekErr() (v T, err error, ok bool) {
 	return zero, nil, false
 }
 
-// SyncFunc wraps a function to make it lazy.
-//
-// The returned function calls fill the first time it's called, and returns
-// fill's result on every subsequent call.
-//
-// The returned function is safe for concurrent use.
-func SyncFunc[T any](fill func() T) func() T {
-	var (
-		once sync.Once
-		v    T
-	)
-	return func() T {
-		once.Do(func() { v = fill() })
-		return v
-	}
-}
-
-// SyncFuncErr wraps a function to make it lazy.
-//
-// The returned function calls fill the first time it's called, and returns
-// fill's results on every subsequent call.
-//
-// The returned function is safe for concurrent use.
-func SyncFuncErr[T any](fill func() (T, error)) func() (T, error) {
-	var (
-		once sync.Once
-		v    T
-		err  error
-	)
-	return func() (T, error) {
-		once.Do(func() { v, err = fill() })
-		return v, err
-	}
-}
-
 // TB is a subset of testing.TB that we use to set up test helpers.
 // It's defined here to avoid pulling in the testing package.
 type TB interface {

types/lazy/sync_test.go

@@ -354,46 +354,3 @@ func TestSyncValueSetForTest(t *testing.T) {
 		})
 	}
 }
-
-func TestSyncFunc(t *testing.T) {
-	f := SyncFunc(fortyTwo)
-
-	n := int(testing.AllocsPerRun(1000, func() {
-		got := f()
-		if got != 42 {
-			t.Fatalf("got %v; want 42", got)
-		}
-	}))
-	if n != 0 {
-		t.Errorf("allocs = %v; want 0", n)
-	}
-}
-
-func TestSyncFuncErr(t *testing.T) {
-	f := SyncFuncErr(func() (int, error) {
-		return 42, nil
-	})
-	n := int(testing.AllocsPerRun(1000, func() {
-		got, err := f()
-		if got != 42 || err != nil {
-			t.Fatalf("got %v, %v; want 42, nil", got, err)
-		}
-	}))
-	if n != 0 {
-		t.Errorf("allocs = %v; want 0", n)
-	}
-
-	wantErr := errors.New("test error")
-	f = SyncFuncErr(func() (int, error) {
-		return 0, wantErr
-	})
-	n = int(testing.AllocsPerRun(1000, func() {
-		got, err := f()
-		if got != 0 || err != wantErr {
-			t.Fatalf("got %v, %v; want 0, %v", got, err, wantErr)
-		}
-	}))
-	if n != 0 {
-		t.Errorf("allocs = %v; want 0", n)
-	}
-}

util/uniq/slice.go

@@ -1,62 +0,0 @@
-// Copyright (c) Tailscale Inc & AUTHORS
-// SPDX-License-Identifier: BSD-3-Clause
-
-// Package uniq provides removal of adjacent duplicate elements in slices.
-// It is similar to the unix command uniq.
-package uniq
-
-// ModifySlice removes adjacent duplicate elements from the given slice. It
-// adjusts the length of the slice appropriately and zeros the tail.
-//
-// ModifySlice does O(len(*slice)) operations.
-func ModifySlice[E comparable](slice *[]E) {
-	// Remove duplicates
-	dst := 0
-	for i := 1; i < len(*slice); i++ {
-		if (*slice)[i] == (*slice)[dst] {
-			continue
-		}
-		dst++
-		(*slice)[dst] = (*slice)[i]
-	}
-
-	// Zero out the elements we removed at the end of the slice
-	end := dst + 1
-	var zero E
-	for i := end; i < len(*slice); i++ {
-		(*slice)[i] = zero
-	}
-
-	// Truncate the slice
-	if end < len(*slice) {
-		*slice = (*slice)[:end]
-	}
-}
-
-// ModifySliceFunc is the same as ModifySlice except that it allows using a
-// custom comparison function.
-//
-// eq should report whether the two provided elements are equal.
-func ModifySliceFunc[E any](slice *[]E, eq func(i, j E) bool) {
-	// Remove duplicates
-	dst := 0
-	for i := 1; i < len(*slice); i++ {
-		if eq((*slice)[dst], (*slice)[i]) {
-			continue
-		}
-		dst++
-		(*slice)[dst] = (*slice)[i]
-	}
-
-	// Zero out the elements we removed at the end of the slice
-	end := dst + 1
-	var zero E
-	for i := end; i < len(*slice); i++ {
-		(*slice)[i] = zero
-	}
-
-	// Truncate the slice
-	if end < len(*slice) {
-		*slice = (*slice)[:end]
-	}
-}

util/uniq/slice_test.go

@@ -1,102 +0,0 @@
-// Copyright (c) Tailscale Inc & AUTHORS
-// SPDX-License-Identifier: BSD-3-Clause
-
-package uniq_test
-
-import (
-	"reflect"
-	"strconv"
-	"testing"
-
-	"tailscale.com/util/uniq"
-)
-
-func runTests(t *testing.T, cb func(*[]uint32)) {
-	tests := []struct {
-		// Use uint32 to be different from an int-typed slice index
-		in   []uint32
-		want []uint32
-	}{
-		{in: []uint32{0, 1, 2}, want: []uint32{0, 1, 2}},
-		{in: []uint32{0, 1, 2, 2}, want: []uint32{0, 1, 2}},
-		{in: []uint32{0, 0, 1, 2}, want: []uint32{0, 1, 2}},
-		{in: []uint32{0, 1, 0, 2}, want: []uint32{0, 1, 0, 2}},
-		{in: []uint32{0}, want: []uint32{0}},
-		{in: []uint32{0, 0}, want: []uint32{0}},
-		{in: []uint32{}, want: []uint32{}},
-	}
-
-	for _, test := range tests {
-		in := make([]uint32, len(test.in))
-		copy(in, test.in)
-		cb(&test.in)
-		if !reflect.DeepEqual(test.in, test.want) {
-			t.Errorf("uniq.Slice(%v) = %v, want %v", in, test.in, test.want)
-		}
-		start := len(test.in)
-		test.in = test.in[:cap(test.in)]
-		for i := start; i < len(in); i++ {
-			if test.in[i] != 0 {
-				t.Errorf("uniq.Slice(%v): non-0 in tail of %v at index %v", in, test.in, i)
-			}
-		}
-	}
-}
-
-func TestModifySlice(t *testing.T) {
-	runTests(t, func(slice *[]uint32) {
-		uniq.ModifySlice(slice)
-	})
-}
-
-func TestModifySliceFunc(t *testing.T) {
-	runTests(t, func(slice *[]uint32) {
-		uniq.ModifySliceFunc(slice, func(i, j uint32) bool {
-			return i == j
-		})
-	})
-}
-
-func Benchmark(b *testing.B) {
-	benches := []struct {
-		name  string
-		reset func(s []byte)
-	}{
-		{name: "AllDups",
-			reset: func(s []byte) {
-				for i := range s {
-					s[i] = '*'
-				}
-			},
-		},
-		{name: "NoDups",
-			reset: func(s []byte) {
-				for i := range s {
-					s[i] = byte(i)
-				}
-			},
-		},
-	}
-
-	for _, bb := range benches {
-		b.Run(bb.name, func(b *testing.B) {
-			for size := 1; size <= 4096; size *= 16 {
-				b.Run(strconv.Itoa(size), func(b *testing.B) {
-					benchmark(b, 64, bb.reset)
-				})
-			}
-		})
-	}
-}
-
-func benchmark(b *testing.B, size int64, reset func(s []byte)) {
-	b.ReportAllocs()
-	b.SetBytes(size)
-	s := make([]byte, size)
-	b.ResetTimer()
-	for range b.N {
-		s = s[:size]
-		reset(s)
-		uniq.ModifySlice(&s)
-	}
-}

version/print.go

@@ -7,11 +7,10 @@ import (
 	"fmt"
 	"runtime"
 	"strings"
-
+	"sync"
-	"tailscale.com/types/lazy"
 )
 
-var stringLazy = lazy.SyncFunc(func() string {
+var stringLazy = sync.OnceValue(func() string {
 	var ret strings.Builder
 	ret.WriteString(Short())
 	ret.WriteByte('\n')

version/prop.go

@@ -9,6 +9,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"sync"
 
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/lazy"
@@ -174,7 +175,7 @@ func IsUnstableBuild() bool {
 	})
 }
 
-var isDev = lazy.SyncFunc(func() bool {
+var isDev = sync.OnceValue(func() bool {
 	return strings.Contains(Short(), "-dev")
 })
 

version/version.go

@@ -9,6 +9,7 @@ import (
 	"runtime/debug"
 	"strconv"
 	"strings"
+	"sync"
 
 	tailscaleroot "tailscale.com"
 	"tailscale.com/types/lazy"
@@ -117,7 +118,7 @@ func (i embeddedInfo) commitAbbrev() string {
 	return i.commit
 }
 
-var getEmbeddedInfo = lazy.SyncFunc(func() embeddedInfo {
+var getEmbeddedInfo = sync.OnceValue(func() embeddedInfo {
 	bi, ok := debug.ReadBuildInfo()
 	if !ok {
 		return embeddedInfo{}

wgengine/magicsock/magicsock.go

@@ -17,6 +17,7 @@ import (
 	"net/netip"
 	"reflect"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -59,7 +60,6 @@ import (
 	"tailscale.com/util/ringbuffer"
 	"tailscale.com/util/set"
 	"tailscale.com/util/testenv"
-	"tailscale.com/util/uniq"
 	"tailscale.com/util/usermetric"
 	"tailscale.com/wgengine/capture"
 	"tailscale.com/wgengine/wgint"
@@ -2666,7 +2666,7 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
 	}
 	ports = append(ports, 0)
 	// Remove duplicates. (All duplicates are consecutive.)
-	uniq.ModifySlice(&ports)
+	ports = slices.Compact(ports)
 
 	if debugBindSocket() {
 		c.logf("magicsock: bindSocket: candidate ports: %+v", ports)

wgengine/pendopen.go

@@ -8,6 +8,7 @@ import (
 	"net/netip"
 	"runtime"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/gaissmai/bart"
@@ -15,7 +16,6 @@ import (
 	"tailscale.com/net/packet"
 	"tailscale.com/net/tstun"
 	"tailscale.com/types/ipproto"
-	"tailscale.com/types/lazy"
 	"tailscale.com/util/mak"
 	"tailscale.com/wgengine/filter"
 )
@@ -91,7 +91,7 @@ func (e *userspaceEngine) trackOpenPreFilterIn(pp *packet.Parsed, t *tstun.Wrapp
 
 var (
 	appleIPRange = netip.MustParsePrefix("17.0.0.0/8")
-	canonicalIPs = lazy.SyncFunc(func() (checkIPFunc func(netip.Addr) bool) {
+	canonicalIPs = sync.OnceValue(func() (checkIPFunc func(netip.Addr) bool) {
 		// https://bgp.he.net/AS41231#_prefixes
 		t := &bart.Table[bool]{}
 		for _, s := range strings.Fields(`