Watch cli efficiency update

internal/execute/tsctests/watcher_race_test.go

@@ -0,0 +1,262 @@
+package tsctests
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/execute"
+)
+
+// createTestWatcher sets up a minimal project with a tsconfig and
+// returns a Watcher ready for concurrent testing, plus the TestSys
+// for file manipulation.
+func createTestWatcher(t *testing.T) (*execute.Watcher, *TestSys) {
+	t.Helper()
+	input := &tscInput{
+		files: FileMap{
+			"/home/src/workspaces/project/a.ts":          `const a: number = 1;`,
+			"/home/src/workspaces/project/b.ts":          `import { a } from "./a"; export const b = a;`,
+			"/home/src/workspaces/project/tsconfig.json": `{}`,
+		},
+		commandLineArgs: []string{"--watch"},
+	}
+	sys := newTestSys(input, false)
+	result := execute.CommandLine(sys, []string{"--watch"}, sys)
+	if result.Watcher == nil {
+		t.Fatal("expected Watcher to be non-nil in watch mode")
+	}
+	w, ok := result.Watcher.(*execute.Watcher)
+	if !ok {
+		t.Fatalf("expected *execute.Watcher, got %T", result.Watcher)
+	}
+	return w, sys
+}
+
+// TestWatcherConcurrentDoCycle calls DoCycle from multiple goroutines
+// while modifying source files, exposing data races on Watcher fields
+// such as configModified, program, config, and the underlying
+// FileWatcher state. Run with -race to detect.
+func TestWatcherConcurrentDoCycle(t *testing.T) {
+	t.Parallel()
+	w, sys := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	for i := range 8 {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := range 10 {
+				_ = sys.fsFromFileMap().WriteFile(
+					"/home/src/workspaces/project/a.ts",
+					fmt.Sprintf("const a: number = %d;", i*10+j),
+				)
+				w.DoCycle()
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
+
+// TestWatcherDoCycleWithConcurrentStateReads calls DoCycle from
+// multiple goroutines, some modifying files and some not, to test
+// concurrent access to all Watcher and FileWatcher state.
+func TestWatcherDoCycleWithConcurrentStateReads(t *testing.T) {
+	t.Parallel()
+	w, sys := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	// DoCycle goroutines
+	for i := range 4 {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := range 15 {
+				_ = sys.fsFromFileMap().WriteFile(
+					"/home/src/workspaces/project/a.ts",
+					fmt.Sprintf("const a: number = %d;", i*15+j),
+				)
+				w.DoCycle()
+			}
+		}(i)
+	}
+
+	// State reader goroutines
+	for range 8 {
+		wg.Go(func() {
+			for range 50 {
+				w.DoCycle()
+				w.DoCycle()
+				w.DoCycle()
+				w.DoCycle()
+			}
+		})
+	}
+
+	wg.Wait()
+}
+
+// TestWatcherConcurrentFileChangesAndDoCycle creates, modifies, and
+// deletes files from multiple goroutines while DoCycle runs, testing
+// races between FS mutations and watch state updates.
+func TestWatcherConcurrentFileChangesAndDoCycle(t *testing.T) {
+	t.Parallel()
+	w, sys := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	// File creators
+	for i := range 4 {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := range 20 {
+				path := fmt.Sprintf("/home/src/workspaces/project/gen_%d_%d.ts", i, j)
+				_ = sys.fsFromFileMap().WriteFile(path, fmt.Sprintf("export const x%d_%d = %d;", i, j, j))
+			}
+		}(i)
+	}
+
+	// File deleters
+	wg.Go(func() {
+		for j := range 20 {
+			_ = sys.fsFromFileMap().Remove(
+				fmt.Sprintf("/home/src/workspaces/project/gen_0_%d.ts", j),
+			)
+		}
+	})
+
+	// DoCycle callers
+	for range 4 {
+		wg.Go(func() {
+			for range 10 {
+				w.DoCycle()
+			}
+		})
+	}
+
+	wg.Wait()
+}
+
+// TestWatcherRapidConfigChanges modifies tsconfig.json rapidly from
+// multiple goroutines while DoCycle runs, testing races on
+// config-related fields (configModified, configHasErrors,
+// configFilePaths, config, extendedConfigCache).
+func TestWatcherRapidConfigChanges(t *testing.T) {
+	t.Parallel()
+	w, sys := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	configs := []string{
+		`{}`,
+		`{"compilerOptions": {"strict": true}}`,
+		`{"compilerOptions": {"target": "ES2020"}}`,
+		`{"compilerOptions": {"noEmit": true}}`,
+	}
+
+	// Config modifiers + DoCycle
+	for i := range 3 {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := range 10 {
+				_ = sys.fsFromFileMap().WriteFile(
+					"/home/src/workspaces/project/tsconfig.json",
+					configs[(i+j)%len(configs)],
+				)
+				w.DoCycle()
+			}
+		}(i)
+	}
+
+	// Concurrent source file modifications
+	for i := range 2 {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := range 15 {
+				_ = sys.fsFromFileMap().WriteFile(
+					"/home/src/workspaces/project/a.ts",
+					fmt.Sprintf("const a: number = %d;", i*15+j),
+				)
+				w.DoCycle()
+			}
+		}(i)
+	}
+
+	// State readers
+	for range 4 {
+		wg.Go(func() {
+			for range 30 {
+				w.DoCycle()
+				w.DoCycle()
+			}
+		})
+	}
+
+	wg.Wait()
+}
+
+// TestWatcherConcurrentDoCycleNoChanges calls DoCycle from many
+// goroutines when no files have changed, testing the early-return
+// path where WatchState is read and HasChanges is called.
+func TestWatcherConcurrentDoCycleNoChanges(t *testing.T) {
+	t.Parallel()
+	w, _ := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	for range 16 {
+		wg.Go(func() {
+			for range 50 {
+				w.DoCycle()
+			}
+		})
+	}
+
+	wg.Wait()
+}
+
+// TestWatcherAlternatingModifyAndDoCycle alternates between modifying
+// a file and calling DoCycle from different goroutines, creating a
+// realistic scenario where the file watcher detects changes mid-cycle.
+func TestWatcherAlternatingModifyAndDoCycle(t *testing.T) {
+	t.Parallel()
+	w, sys := createTestWatcher(t)
+
+	var wg sync.WaitGroup
+
+	// Writer goroutine: continuously modifies files
+	wg.Go(func() {
+		for j := range 100 {
+			_ = sys.fsFromFileMap().WriteFile(
+				"/home/src/workspaces/project/a.ts",
+				fmt.Sprintf("const a: number = %d;", j),
+			)
+		}
+	})
+
+	// Multiple DoCycle goroutines
+	for range 4 {
+		wg.Go(func() {
+			for range 25 {
+				w.DoCycle()
+			}
+		})
+	}
+
+	// State reader goroutines
+	for range 4 {
+		wg.Go(func() {
+			for range 100 {
+				w.DoCycle()
+			}
+		})
+	}
+
+	wg.Wait()
+}