Add -bufsize flag, resilient walk, and diagnostic logging for Windows watcher

1 files changed, 32 insertions, 11 deletions

diff --git a/cmd_windows.go b/cmd_windows.go
index ef06227..f728182 100644
--- a/cmd_windows.go
+++ b/cmd_windows.go
@@ -18,15 +18,16 @@ import (
 )
 
 var (
-	sourceDir = flag.String("dir", "", "Source directory to watch (required)")
-	connect   = flag.String("connect", "localhost:5151", "TCP address of the container to connect to")
+	sourceDir  = flag.String("dir", "", "Source directory to watch (required)")
+	connect    = flag.String("connect", "localhost:5151", "TCP address of the container to connect to")
+	bufSizeKB  = flag.Int("bufsize", 256, "ReadDirectoryChangesW buffer size in KB per directory (default 256)")
 )
 
 func run() {
 	flag.Parse()
 
 	if *sourceDir == "" {
-		fmt.Fprintln(os.Stderr, "Usage: sourcewatch.exe -dir <source> [-connect host:port]")
+		fmt.Fprintln(os.Stderr, "Usage: sourcewatch.exe -dir <source> [-connect host:port] [-bufsize KB]")
 		os.Exit(1)
 	}
 
@@ -157,19 +158,28 @@ func watchLoop(ctx context.Context, conn net.Conn, watcher *fsnotify.Watcher, ma
 				srcPath := filepath.Join(*sourceDir, relPath)
 				info, err := os.Lstat(srcPath)
 				if err == nil && info.IsDir() {
+					bufBytes := *bufSizeKB * 1024
 					if hasGitignore(srcPath) {
 						stack.Push(srcPath)
 					}
-					if err := watcher.Add(srcPath); err != nil {
+					if err := watcher.AddWith(srcPath, fsnotify.WithBufferSize(bufBytes)); err != nil {
 						logErrorf("watch %s: %v", relPath, err)
 					}
+					var added int
 					filepath.Walk(srcPath, func(path string, info os.FileInfo, err error) error {
 						if err != nil || !info.IsDir() || path == srcPath {
 							return nil
 						}
-						watcher.Add(path)
+						if err := watcher.AddWith(path, fsnotify.WithBufferSize(bufBytes)); err != nil {
+							logDebug("watch sub %s: %v", path, err)
+						} else {
+							added++
+						}
 						return nil
 					})
+					if added > 0 {
+						logDebug("added %d sub-watchers for %s", added, relPath)
+					}
 				}
 			}
 
@@ -378,15 +388,18 @@ func sendEvent(conn net.Conn, evt FileEvent) error {
 }
 
 func addWatchersRecursively(watcher *fsnotify.Watcher, root string, stack *GitignoreStack) error {
-	count := 0
+	var count, failCount, skippedCount int
+	bufBytes := *bufSizeKB * 1024
 	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
-			return err
+			logDebug("walk error: %v", err)
+			return nil // continue walking even if we can't stat a path
 		}
 
 		relPath, err := filepath.Rel(root, path)
 		if err != nil {
-			return err
+			logDebug("rel error: %v", err)
+			return nil
 		}
 
 		if isGitDir(relPath) {
@@ -401,16 +414,24 @@ func addWatchersRecursively(watcher *fsnotify.Watcher, root string, stack *Gitig
 				stack.Push(path)
 			}
 			if !stack.IsIgnored(relPath) {
-				if err := watcher.Add(path); err != nil {
-					logErrorf("watch %s: %v", relPath, err)
+				if err := watcher.AddWith(path, fsnotify.WithBufferSize(bufBytes)); err != nil {
+					failCount++
+					if failCount <= 10 {
+						logErrorf("watch %s: %v", relPath, err)
+					}
 				} else {
 					count++
 				}
+			} else {
+				skippedCount++
 			}
 		}
 
 		return nil
 	})
-	logInfo("watcher: watching %d directories", count)
+	if failCount > 10 {
+		logErrorf("watcher: %d additional watch failures (suppressed)", failCount-10)
+	}
+	logInfo("watcher: watching %d directories, skipped %d ignored, %d failed (buffer=%dKB)", count, skippedCount, failCount, *bufSizeKB)
 	return err
 }