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.Pointer[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/peerapi_test.go

@@ -504,7 +504,7 @@ func TestDeletedMarkers(t *testing.T) {
 
 	nothingWaiting := func() {
 		t.Helper()
-		ps.knownEmpty.Set(false)
+		ps.knownEmpty.Store(false)
 		if ps.hasFilesWaiting() {
 			t.Fatal("unexpected files waiting")
 		}

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
@@ -108,7 +108,7 @@ func newMockControl(tb testing.TB) *mockControl {
 }
 
 func (cc *mockControl) logf(format string, args ...any) {
-	if cc.preventLog.Get() || cc.logfActual == nil {
+	if cc.preventLog.Load() || cc.logfActual == nil {
 		return
 	}
 	cc.logfActual(format, args...)
@@ -292,7 +292,7 @@ func TestStateMachine(t *testing.T) {
 
 	cc := newMockControl(t)
 	cc.statusFunc = b.setClientStatus
-	t.Cleanup(func() { cc.preventLog.Set(true) }) // hacky way to pacify issue 3020
+	t.Cleanup(func() { cc.preventLog.Store(true) }) // hacky way to pacify issue 3020
 
 	b.SetControlClientGetterForTesting(func(opts controlclient.Options) (controlclient.Client, error) {
 		cc.mu.Lock()
@@ -311,7 +311,7 @@ func TestStateMachine(t *testing.T) {
 	notifies.expect(0)
 
 	b.SetNotifyCallback(func(n ipn.Notify) {
-		if cc.preventLog.Get() {
+		if cc.preventLog.Load() {
 			return
 		}
 		if n.State != nil ||
@@ -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) {
@@ -928,18 +928,18 @@ func (s *testStateStorage) ReadState(id ipn.StateKey) ([]byte, error) {
 }
 
 func (s *testStateStorage) WriteState(id ipn.StateKey, bs []byte) error {
-	s.written.Set(true)
+	s.written.Store(true)
 	return s.mem.WriteState(id, bs)
 }
 
 // awaitWrite clears the "I've seen writes" bit, in prep for a future
 // call to sawWrite to see if a write arrived.
-func (s *testStateStorage) awaitWrite() { s.written.Set(false) }
+func (s *testStateStorage) awaitWrite() { s.written.Store(false) }
 
 // sawWrite reports whether there's been a WriteState call since the most
 // recent awaitWrite call.
 func (s *testStateStorage) sawWrite() bool {
-	v := s.written.Get()
+	v := s.written.Load()
 	s.awaitWrite()
 	return v
 }