syncs, all: move to using Go's new atomic types instead of ours

Fixes #5185

Change-Id: I850dd532559af78c3895e2924f8237ccc328449d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/local.go

@@ -40,7 +40,6 @@ import (
 	"tailscale.com/net/tsdial"
 	"tailscale.com/paths"
 	"tailscale.com/portlist"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tka"
 	"tailscale.com/types/dnstype"
@@ -127,7 +126,7 @@ type LocalBackend struct {
 	serverURL             string           // tailcontrol URL
 	newDecompressor       func() (controlclient.Decompressor, error)
 	varRoot               string // or empty if SetVarRoot never called
-	sshAtomicBool         syncs.AtomicBool
+	sshAtomicBool         atomic.Bool
 	shutdownCalled        bool // if Shutdown has been called
 
 	filterAtomic            atomic.Value // of *filter.Filter
@@ -1740,7 +1739,7 @@ func (b *LocalBackend) loadStateLocked(key ipn.StateKey, prefs *ipn.Prefs) (err
 // setAtomicValuesFromPrefs populates sshAtomicBool and containsViaIPFuncAtomic
 // from the prefs p, which may be nil.
 func (b *LocalBackend) setAtomicValuesFromPrefs(p *ipn.Prefs) {
-	b.sshAtomicBool.Set(p != nil && p.RunSSH && canSSH)
+	b.sshAtomicBool.Store(p != nil && p.RunSSH && canSSH)
 
 	if p == nil {
 		b.containsViaIPFuncAtomic.Store(tsaddr.NewContainsIPFunc(nil))
@@ -3053,7 +3052,7 @@ func (b *LocalBackend) ResetForClientDisconnect() {
 	b.setAtomicValuesFromPrefs(nil)
 }
 
-func (b *LocalBackend) ShouldRunSSH() bool { return b.sshAtomicBool.Get() && canSSH }
+func (b *LocalBackend) ShouldRunSSH() bool { return b.sshAtomicBool.Load() && canSSH }
 
 // ShouldHandleViaIP reports whether whether ip is an IPv6 address in the
 // Tailscale ULA's v6 "via" range embedding an IPv4 address to be forwarded to

ipn/ipnlocal/peerapi.go

@@ -26,6 +26,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 	"unicode"
 	"unicode/utf8"
@@ -41,7 +42,6 @@ import (
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netaddr"
 	"tailscale.com/net/netutil"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/wgengine"
@@ -58,7 +58,7 @@ type peerAPIServer struct {
 	b          *LocalBackend
 	rootDir    string // empty means file receiving unavailable
 	selfNode   *tailcfg.Node
-	knownEmpty syncs.AtomicBool
+	knownEmpty atomic.Bool
 	resolver   *resolver.Resolver
 
 	// directFileMode is whether we're writing files directly to a
@@ -144,7 +144,7 @@ func (s *peerAPIServer) hasFilesWaiting() bool {
 	if s == nil || s.rootDir == "" || s.directFileMode {
 		return false
 	}
-	if s.knownEmpty.Get() {
+	if s.knownEmpty.Load() {
 		// Optimization: this is usually empty, so avoid opening
 		// the directory and checking. We can't cache the actual
 		// has-files-or-not values as the macOS/iOS client might
@@ -185,7 +185,7 @@ func (s *peerAPIServer) hasFilesWaiting() bool {
 			}
 		}
 		if err == io.EOF {
-			s.knownEmpty.Set(true)
+			s.knownEmpty.Store(true)
 		}
 		if err != nil {
 			break
@@ -808,7 +808,7 @@ func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
 	// TODO: some real response
 	success = true
 	io.WriteString(w, "{}\n")
-	h.ps.knownEmpty.Set(false)
+	h.ps.knownEmpty.Store(false)
 	h.ps.b.sendFileNotify()
 }
 

ipn/ipnlocal/state_test.go

@@ -7,6 +7,7 @@ package ipnlocal
 import (
 	"context"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -15,7 +16,6 @@ import (
 	"tailscale.com/control/controlclient"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/store/mem"
-	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
@@ -91,7 +91,7 @@ type mockControl struct {
 	opts       controlclient.Options
 	logfActual logger.Logf
 	statusFunc func(controlclient.Status)
-	preventLog syncs.AtomicBool
+	preventLog atomic.Bool
 
 	mu          sync.Mutex
 	calls       []string
@@ -920,7 +920,7 @@ func TestStateMachine(t *testing.T) {
 
 type testStateStorage struct {
 	mem     mem.Store
-	written syncs.AtomicBool
+	written atomic.Bool
 }
 
 func (s *testStateStorage) ReadState(id ipn.StateKey) ([]byte, error) {