all: use sync.WaitGroup.Go

Drops the Add/Done bookkeeping, which in batcher.go was spread across
three functions.

hscontrol/mapper/batcher.go

@@ -403,9 +403,7 @@ func (b *Batcher) Start() {
 		return
 	}
 
-	b.wg.Add(1)
+	b.wg.Go(b.doWork)
-
-	go b.doWork()
 }
 
 func (b *Batcher) Close() {
@@ -439,12 +437,8 @@ func (b *Batcher) Close() {
 }
 
 func (b *Batcher) doWork() {
-	defer b.wg.Done()
-
 	for i := range b.workers {
-		b.wg.Add(1)
+		b.wg.Go(func() { b.worker(i + 1) })
-
-		go b.worker(i + 1)
 	}
 
 	// Create a cleanup ticker for removing truly disconnected nodes
@@ -467,8 +461,6 @@ func (b *Batcher) doWork() {
 }
 
 func (b *Batcher) worker(workerID int) {
-	defer b.wg.Done()
-
 	wlog := log.With().Int(zf.WorkerID, workerID).Logger()
 
 	for {

hscontrol/mapper/batcher_concurrency_test.go

@@ -142,19 +142,16 @@ func runConcurrently(t *testing.T, n int, fn func(i int)) int {
 	)
 
 	for i := range n {
-		wg.Add(1)
+		wg.Go(func() {
-
-		go func(idx int) {
-			defer wg.Done()
 			defer func() {
 				if r := recover(); r != nil {
 					panics.Add(1)
-					t.Logf("panic in goroutine %d: %v", idx, r)
+					t.Logf("panic in goroutine %d: %v", i, r)
 				}
 			}()
 
-			fn(idx)
+			fn(i)
-		}(i)
+		})
 	}
 
 	wg.Wait()

hscontrol/servertest/connect_race_test.go

@@ -96,22 +96,16 @@ func TestConnectDisconnectRace(t *testing.T) {
 
 		start := make(chan struct{})
 
-		wg.Add(2)
+		wg.Go(func() {
-
-		go func() {
-			defer wg.Done()
-
 			<-start
 
 			_, _ = srv.State().Disconnect(r2ID, gen)
-		}()
+		})
-		go func() {
+		wg.Go(func() {
-			defer wg.Done()
-
 			<-start
 
 			_, _ = srv.State().Connect(r2ID)
-		}()
+		})
 
 		close(start)
 		wg.Wait()

hscontrol/servertest/race_test.go

@@ -494,16 +494,12 @@ func TestRaceBatcherContention(t *testing.T) {
 			srv.App.Change(c)
 		})
 
-		wg.Add(1)
-
 		var c2 *servertest.TestClient
 
-		go func() {
+		wg.Go(func() {
-			defer wg.Done()
-
 			c2 = servertest.NewClient(t, srv, "rtcon-node2",
 				servertest.WithUser(user))
-		}()
+		})
 
 		wg.Wait()
 

hscontrol/state/node_store_hostname_test.go

@@ -104,17 +104,13 @@ func TestConcurrentPutNodeSameGivenNameAllUnique(t *testing.T) {
 	var wg sync.WaitGroup
 
 	results := make(chan string, N)
-	for i := range N {
+	for id := range N {
-		wg.Add(1)
+		wg.Go(func() {
-
-		go func(id int) {
-			defer wg.Done()
-
 			n := createTestNode(types.NodeID(id+1), 1, "alice", "laptop") //nolint:gosec // test ids
 
 			view := store.PutNode(n)
 			results <- view.GivenName()
-		}(i)
+		})
 	}
 
 	wg.Wait()

hscontrol/state/node_store_test.go

@@ -901,17 +901,13 @@ func TestNodeStoreConcurrentPutNode(t *testing.T) {
 	var wg sync.WaitGroup
 
 	results := make(chan bool, concurrentOps)
-	for i := range concurrentOps {
+	for nodeID := 1; nodeID <= concurrentOps; nodeID++ {
-		wg.Add(1)
+		wg.Go(func() {
-
-		go func(nodeID int) {
-			defer wg.Done()
-
 			node := createConcurrentTestNode(types.NodeID(nodeID), "concurrent-node") //nolint:gosec // safe conversion in test
 
 			resultNode := store.PutNode(node)
 			results <- resultNode.Valid()
-		}(i + 1)
+		})
 	}
 
 	wg.Wait()
@@ -940,17 +936,13 @@ func TestNodeStoreBatchingEfficiency(t *testing.T) {
 	var wg sync.WaitGroup
 
 	results := make(chan bool, ops)
-	for i := range ops {
+	for nodeID := 1; nodeID <= ops; nodeID++ {
-		wg.Add(1)
+		wg.Go(func() {
-
-		go func(nodeID int) {
-			defer wg.Done()
-
 			node := createConcurrentTestNode(types.NodeID(nodeID), "batch-node") //nolint:gosec // test code with small integers
 
 			resultNode := store.PutNode(node)
 			results <- resultNode.Valid()
-		}(i + 1)
+		})
 	}
 
 	wg.Wait()
@@ -988,12 +980,8 @@ func TestNodeStoreRaceConditions(t *testing.T) {
 
 	errors := make(chan error, numGoroutines*opsPerGoroutine)
 
-	for i := range numGoroutines {
+	for gid := range numGoroutines {
-		wg.Add(1)
+		wg.Go(func() {
-
-		go func(gid int) {
-			defer wg.Done()
-
 			for j := range opsPerGoroutine {
 				switch j % 3 {
 				case 0:
@@ -1017,7 +1005,7 @@ func TestNodeStoreRaceConditions(t *testing.T) {
 					}
 				}
 			}
-		}(i)
+		})
 	}
 
 	wg.Wait()
@@ -1097,14 +1085,10 @@ func TestNodeStoreOperationTimeout(t *testing.T) {
 	updateResults := make([]error, ops)
 
 	// Launch all PutNode operations concurrently
-	for i := 1; i <= ops; i++ {
+	for idx := 1; idx <= ops; idx++ {
-		nodeID := types.NodeID(i) //nolint:gosec // test code with small integers
+		id := types.NodeID(idx) //nolint:gosec // test code with small integers
-
-		wg.Add(1)
-
-		go func(idx int, id types.NodeID) {
-			defer wg.Done()
 
+		wg.Go(func() {
 			startPut := time.Now()
 			fmt.Printf("[TestNodeStoreOperationTimeout] %s: PutNode(%d) starting\n", startPut.Format("15:04:05.000"), id)
 			node := createConcurrentTestNode(id, "timeout-node")
@@ -1115,7 +1099,7 @@ func TestNodeStoreOperationTimeout(t *testing.T) {
 			if !resultNode.Valid() {
 				putResults[idx-1] = fmt.Errorf("PutNode failed for node %d", id) //nolint:err113
 			}
-		}(i, nodeID)
+		})
 	}
 
 	wg.Wait()
@@ -1123,14 +1107,10 @@ func TestNodeStoreOperationTimeout(t *testing.T) {
 	// Launch all UpdateNode operations concurrently
 	wg = sync.WaitGroup{}
 
-	for i := 1; i <= ops; i++ {
+	for idx := 1; idx <= ops; idx++ {
-		nodeID := types.NodeID(i) //nolint:gosec // test code with small integers
+		id := types.NodeID(idx) //nolint:gosec // test code with small integers
-
-		wg.Add(1)
-
-		go func(idx int, id types.NodeID) {
-			defer wg.Done()
 
+		wg.Go(func() {
 			startUpdate := time.Now()
 			fmt.Printf("[TestNodeStoreOperationTimeout] %s: UpdateNode(%d) starting\n", startUpdate.Format("15:04:05.000"), id)
 			resultNode, ok := store.UpdateNode(id, func(n *types.Node) {
@@ -1142,7 +1122,7 @@ func TestNodeStoreOperationTimeout(t *testing.T) {
 			if !ok || !resultNode.Valid() {
 				updateResults[idx-1] = fmt.Errorf("UpdateNode failed for node %d", id) //nolint:err113
 			}
-		}(i, nodeID)
+		})
 	}
 
 	done := make(chan struct{})

hscontrol/state/ping_test.go

@@ -1,6 +1,7 @@
 package state
 
 import (
+	"slices"
 	"sync"
 	"testing"
 	"time"
@@ -79,14 +80,10 @@ func TestPingTracker_ConcurrentDifferentIDs(t *testing.T) {
 	// Complete in reverse order concurrently.
 	var wg sync.WaitGroup
 
-	for i := count - 1; i >= 0; i-- {
+	for _, id := range slices.Backward(ids) {
-		wg.Add(1)
+		wg.Go(func() {
-
+			assert.True(t, pt.complete(id))
-		go func(idx int) {
+		})
-			defer wg.Done()
-
-			assert.True(t, pt.complete(ids[idx]))
-		}(i)
 	}
 
 	// All channels should receive.

hscontrol/state/ssh_check_test.go

@@ -85,19 +85,13 @@ func TestSSHCheckAuthConcurrent(t *testing.T) {
 	wg.Wait()
 
 	// Clear concurrently with reads
-	wg.Add(2)
+	wg.Go(func() {
-
-	go func() {
-		defer wg.Done()
-
 		s.ClearSSHCheckAuth()
-	}()
+	})
-
-	go func() {
-		defer wg.Done()
 
+	wg.Go(func() {
 		s.GetLastSSHAuth(types.NodeID(1), types.NodeID(2))
-	}()
+	})
 
 	wg.Wait()
 }

integration/helpers.go

@@ -735,17 +735,11 @@ func assertClientsState(t *testing.T, clients []TailscaleClient) {
 	var wg sync.WaitGroup
 
 	for _, client := range clients {
-		wg.Add(1)
+		wg.Go(func() {
-
+			assertValidStatus(t, client)
-		c := client // Avoid loop pointer
+			assertValidNetcheck(t, client)
-
+			assertValidNetmap(t, client)
-		go func() {
+		})
-			defer wg.Done()
-
-			assertValidStatus(t, c)
-			assertValidNetcheck(t, c)
-			assertValidNetmap(t, c)
-		}()
 	}
 
 	t.Logf("waiting for client state checks to finish")