refactor: reuse the filewatcher for file-provider (#4807)

reuse filewatcher

Signed-off-by: shawnh2 <[email protected]>
Co-authored-by: zirain <[email protected]>

internal/filewatcher/filewatcher.go

@@ -8,6 +8,7 @@ package filewatcher
 import (
 	"errors"
 	"fmt"
+	"os"
 	"path/filepath"
 	"sync"
 
@@ -90,7 +91,6 @@ func (fw *fileWatcher) Add(path string) error {
 	return err
 }
 
-// Stop watching a path
 func (fw *fileWatcher) Remove(path string) error {
 	fw.mu.Lock()
 	defer fw.mu.Unlock()
@@ -142,9 +142,7 @@ func (fw *fileWatcher) getWorker(path string) (*workerState, string, string, err
 		return nil, "", "", errors.New("using a closed watcher")
 	}
 
-	cleanedPath := filepath.Clean(path)
-	parentPath, _ := filepath.Split(cleanedPath)
-
+	cleanedPath, parentPath := getPath(path)
 	ws, workerExists := fw.workers[parentPath]
 	if !workerExists {
 		wk, err := newWorker(parentPath, fw.funcs)
@@ -167,8 +165,7 @@ func (fw *fileWatcher) findWorker(path string) (*workerState, string, error) {
 		return nil, "", errors.New("using a closed watcher")
 	}
 
-	cleanedPath := filepath.Clean(path)
-	parentPath, _ := filepath.Split(cleanedPath)
+	cleanedPath, parentPath := getPath(path)
 
 	ws, workerExists := fw.workers[parentPath]
 	if !workerExists {
@@ -177,3 +174,13 @@ func (fw *fileWatcher) findWorker(path string) (*workerState, string, error) {
 
 	return ws, cleanedPath, nil
 }
+
+func getPath(path string) (cleanedPath, parentPath string) {
+	cleanedPath = filepath.Clean(path)
+	parentPath, _ = filepath.Split(cleanedPath)
+	if f, err := os.Lstat(cleanedPath); err == nil && f.IsDir() {
+		parentPath = cleanedPath
+	}
+
+	return
+}

internal/filewatcher/filewatcher_test.go

@@ -14,6 +14,7 @@ import (
 	"runtime"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/fsnotify/fsnotify"
 	"github.com/stretchr/testify/require"
@@ -173,6 +174,44 @@ func TestWatchFile(t *testing.T) {
 	})
 }
 
+func TestWatchDir(t *testing.T) {
+	// Given a file being watched
+	watchFile := newWatchFile(t)
+	_, err := os.Stat(watchFile)
+	require.NoError(t, err)
+
+	w := NewWatcher()
+	defer func() {
+		_ = w.Close()
+	}()
+	d := path.Dir(watchFile)
+	require.NoError(t, w.Add(d))
+
+	timeout := time.After(5 * time.Second)
+
+	wg := sync.WaitGroup{}
+	var timeoutErr error
+	wg.Add(1)
+	go func() {
+		select {
+		case <-w.Events(d):
+
+		case <-w.Events(watchFile):
+
+		case <-timeout:
+			timeoutErr = errors.New("timeout")
+		}
+		wg.Done()
+	}()
+
+	// Overwriting the file and waiting its event to be received.
+	err = os.WriteFile(watchFile, []byte("foo: baz\n"), 0o600)
+	require.NoError(t, err)
+	wg.Wait()
+
+	require.NoErrorf(t, timeoutErr, "timeout waiting for event")
+}
+
 func TestWatcherLifecycle(t *testing.T) {
 	watchFile1, watchFile2 := newTwoWatchFile(t)
 
@@ -295,27 +334,23 @@ func TestBadAddWatcher(t *testing.T) {
 
 func TestDuplicateAdd(t *testing.T) {
 	w := NewWatcher()
-
 	name := newWatchFile(t)
+	defer func() {
+		_ = w.Close()
+		_ = os.Remove(name)
+	}()
 
-	if err := w.Add(name); err != nil {
-		t.Errorf("Expecting nil, got %v", err)
-	}
-
-	if err := w.Add(name); err == nil {
-		t.Errorf("Expecting error, got nil")
-	}
-
-	_ = w.Close()
+	require.NoError(t, w.Add(name))
+	require.Error(t, w.Add(name))
 }
 
 func TestBogusRemove(t *testing.T) {
 	w := NewWatcher()
-
 	name := newWatchFile(t)
-	if err := w.Remove(name); err == nil {
-		t.Errorf("Expecting error, got nil")
-	}
+	defer func() {
+		_ = w.Close()
+		_ = os.Remove(name)
+	}()
 
-	_ = w.Close()
+	require.Error(t, w.Remove(name))
 }

internal/filewatcher/worker.go

@@ -20,7 +20,7 @@ import (
 type worker struct {
 	mu sync.RWMutex
 
-	// watcher is an fsnotify watcher that watches the parent
+	// watcher is a fsnotify watcher that watches the parent
 	// dir of watchedFiles.
 	dirWatcher *fsnotify.Watcher
 
@@ -96,10 +96,9 @@ func (wk *worker) loop() {
 					continue
 				}
 
-				sum := getHashSum(path)
-				if !bytes.Equal(sum, ft.hash) {
+				sum, isDir := getHashSum(path)
+				if isDir || !bytes.Equal(sum, ft.hash) {
 					ft.hash = sum
-
 					select {
 					case ft.events <- event:
 						// nothing to do
@@ -141,7 +140,7 @@ func (wk *worker) loop() {
 	}
 }
 
-// used only by the worker goroutine
+// drainRetiringTrackers used only by the worker goroutine
 func (wk *worker) drainRetiringTrackers() {
 	// cleanup any trackers that were in the process
 	// of being retired, but didn't get processed due
@@ -156,7 +155,7 @@ func (wk *worker) drainRetiringTrackers() {
 	}
 }
 
-// make a local copy of the set of trackers to avoid contention with callers
+// getTrackers make a local copy of the set of trackers to avoid contention with callers
 // used only by the worker goroutine
 func (wk *worker) getTrackers() map[string]*fileTracker {
 	wk.mu.RLock()
@@ -184,36 +183,34 @@ func (wk *worker) terminate() {
 
 func (wk *worker) addPath(path string) error {
 	wk.mu.Lock()
+	defer wk.mu.Unlock()
 
 	ft := wk.watchedFiles[path]
 	if ft != nil {
-		wk.mu.Unlock()
 		return fmt.Errorf("path %s is already being watched", path)
 	}
 
+	h, _ := getHashSum(path)
 	ft = &fileTracker{
 		events: make(chan fsnotify.Event),
 		errors: make(chan error),
-		hash:   getHashSum(path),
+		hash:   h,
 	}
-
 	wk.watchedFiles[path] = ft
-	wk.mu.Unlock()
 
 	return nil
 }
 
 func (wk *worker) removePath(path string) error {
 	wk.mu.Lock()
+	defer wk.mu.Unlock()
 
 	ft := wk.watchedFiles[path]
 	if ft == nil {
-		wk.mu.Unlock()
 		return fmt.Errorf("path %s not found", path)
 	}
 
 	delete(wk.watchedFiles, path)
-	wk.mu.Unlock()
 
 	wk.retireTrackerCh <- ft
 	return nil
@@ -241,16 +238,26 @@ func (wk *worker) errorChannel(path string) chan error {
 	return nil
 }
 
-// gets the hash of the given file, or nil if there's a problem
-func getHashSum(file string) []byte {
+// getHashSum return the hash of the given file, or nil if there's a problem, or it's a directory.
+func getHashSum(file string) ([]byte, bool) {
 	f, err := os.Open(file)
 	if err != nil {
-		return nil
+		return nil, false
 	}
-	defer f.Close()
-	r := bufio.NewReader(f)
+	defer func() {
+		_ = f.Close()
+	}()
 
+	fi, err := f.Stat()
+	if err != nil {
+		return nil, false
+	}
+	if fi.IsDir() {
+		return nil, true
+	}
+
+	r := bufio.NewReader(f)
 	h := sha256.New()
 	_, _ = io.Copy(h, r)
-	return h.Sum(nil)
+	return h.Sum(nil), false
 }