From 097c4b3d84867abf7292a82faf3fbec898830d36 Mon Sep 17 00:00:00 2001
From: Christian Schmied <cs8898@gmx.de>
Date: Thu, 10 Oct 2024 16:12:29 +0200
Subject: [PATCH] implement in order of creation for oldFiles

---
 folderwatcher.go                      | 102 +++++++++++-----
 folderwatcher_globbing_test.go        | 162 ++++++++++++++++++++++++++
 folderwatcher_oldFilesInOrder_test.go |  87 ++++++++++++++
 folderwatcher_test.go                 | 152 ------------------------
 4 files changed, 324 insertions(+), 179 deletions(-)
 create mode 100644 folderwatcher_globbing_test.go
 create mode 100644 folderwatcher_oldFilesInOrder_test.go

diff --git a/folderwatcher.go b/folderwatcher.go
index 596ff7e..e454da3 100644
--- a/folderwatcher.go
+++ b/folderwatcher.go
@@ -5,6 +5,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"sync"
 	"time"
 
@@ -22,8 +23,10 @@ type FolderWatcher struct {
 	quit          chan struct{}
 	mutex         sync.Mutex
 	wg            sync.WaitGroup
+	debounceWg    sync.WaitGroup
 	debounceMap   map[string]*time.Timer
 	debouncedChan chan string
+	existingList  []string
 	enqueuedFiles int
 }
 
@@ -71,6 +74,7 @@ func NewFolderWatcher(conf Config, includeExisting bool, quit chan struct{}) (*F
 		quit:          quit,
 		debounceMap:   make(map[string]*time.Timer),
 		debouncedChan: make(chan string),
+		existingList:  []string{},
 	}
 
 	if includeExisting {
@@ -81,10 +85,18 @@ func NewFolderWatcher(conf Config, includeExisting bool, quit chan struct{}) (*F
 			}
 			for _, entry := range entries {
 				if !entry.IsDir() {
-					folderWatcher.foundFileEvent(filepath.Join(path, entry.Name()))
+					fullFilePath := filepath.Join(path, entry.Name())
+					if folderWatcher.matchesPattern(fullFilePath) {
+						folderWatcher.existingList = append(folderWatcher.existingList, fullFilePath)
+					}
 				}
 			}
 		}
+		slices.SortFunc(folderWatcher.existingList, func(a, b string) int {
+			infoA, _ := os.Stat(a)
+			infoB, _ := os.Stat(b)
+			return infoA.ModTime().Compare(infoB.ModTime())
+		})
 	}
 
 	return folderWatcher, nil
@@ -95,21 +107,14 @@ type HandlerCallback func(path string, err error)
 
 func (w *FolderWatcher) Watch(handler FileHandler, callback HandlerCallback) {
 	defer w.watcher.Close()
-	for stopped := false; !stopped; {
-		select {
-		case <-w.quit:
-			logger.Info("Stopping watcher")
-			stopped = true
-		case event, ok := <-w.watcher.Events:
-			if !ok {
-				stopped = true
-				break
-			}
-			logger.Debug("event:", event)
-			if event.Has(fsnotify.Write) || event.Has(fsnotify.Create) {
-				w.foundFileEvent(event.Name)
-			}
-		case file, _ := <-w.debouncedChan:
+	initialWait := sync.WaitGroup{}
+
+	handlerWg := sync.WaitGroup{}
+	handlerWg.Add(1)
+	// Start File Handling
+	go func() {
+		defer handlerWg.Done()
+		for file := range w.debouncedChan {
 			triggerCallback, err := handler(file)
 			if err != nil {
 				logger.Warn("error during handle:", err)
@@ -117,7 +122,42 @@ func (w *FolderWatcher) Watch(handler FileHandler, callback HandlerCallback) {
 			if triggerCallback {
 				callback(file, err)
 			}
-			w.wg.Done()
+			w.wg.Done() // mark enqueued file as done
+		}
+	}()
+
+	if len(w.existingList) > 0 {
+		logger.Infof("got %d existing files", len(w.existingList))
+		initialWait.Add(1)
+		go func() {
+			defer initialWait.Done()
+			for _, path := range w.existingList {
+				w.enqueue(path)
+			}
+		}()
+	}
+
+	// Start Event Handling
+	for stopped := false; !stopped; {
+		select {
+		case <-w.quit:
+			logger.Info("Stopping watcher")
+			w.debounceWg.Wait()    // wait for debounce to settle
+			w.wg.Wait()            // wait for existing files to be handled
+			close(w.debouncedChan) //close the debounced chan to mark it as done
+			stopped = true
+		case event, ok := <-w.watcher.Events:
+			initialWait.Wait() // wait that all initial are enqueued, before handling of first event
+			if !ok {
+				stopped = true
+				break
+			}
+			logger.Debug("event:", event)
+			if event.Has(fsnotify.Write) || event.Has(fsnotify.Create) {
+				if w.matchesPattern(event.Name) {
+					w.enqueueDebounce(event.Name)
+				}
+			}
 		case err, ok := <-w.watcher.Errors:
 			if !ok {
 				stopped = true
@@ -126,31 +166,39 @@ func (w *FolderWatcher) Watch(handler FileHandler, callback HandlerCallback) {
 			logger.Warn("error:", err)
 		}
 	}
-	w.wg.Wait()
+	handlerWg.Wait() // wait for filehandler to be closed, implies debouncedChan is closed
 	logger.Infof("watcher handled %d files", w.enqueuedFiles)
 }
 
-func (w *FolderWatcher) foundFileEvent(fileName string) {
+func (w *FolderWatcher) matchesPattern(fileName string) bool {
 	baseName := filepath.Base(fileName)
-	if w.regex == nil || w.regex.MatchString(baseName) {
-		w.enqueueDebounce(fileName)
+	return w.regex == nil || w.regex.MatchString(baseName)
+}
+
+func (w *FolderWatcher) enqueue(f string) {
+	w.wg.Add(1)
+	w.mutex.Lock()
+	defer w.mutex.Unlock()
+	if timer, ok := w.debounceMap[f]; ok && timer != nil {
+		timer.Stop()
 	}
+	delete(w.debounceMap, f)
+	w.enqueuedFiles = w.enqueuedFiles + 1
+	w.debouncedChan <- f
 }
 
 func (w *FolderWatcher) enqueueDebounce(f string) {
+	logger.Infof("Debounced Enqueue of %s", f)
 	w.mutex.Lock()
 	defer w.mutex.Unlock()
 
 	if timer, ok := w.debounceMap[f]; ok && timer != nil {
 		timer.Stop()
 	} else {
-		w.wg.Add(1)
+		w.debounceWg.Add(1)
 	}
 	w.debounceMap[f] = time.AfterFunc(DebounceTime, func() {
-		w.mutex.Lock()
-		defer w.mutex.Unlock()
-		delete(w.debounceMap, f)
-		w.enqueuedFiles = w.enqueuedFiles + 1
-		w.debouncedChan <- f
+		defer w.debounceWg.Done()
+		w.enqueue(f)
 	})
 }
diff --git a/folderwatcher_globbing_test.go b/folderwatcher_globbing_test.go
new file mode 100644
index 0000000..a6feb00
--- /dev/null
+++ b/folderwatcher_globbing_test.go
@@ -0,0 +1,162 @@
+package folderwatcher
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+)
+
+func TestGlobbingN1(t *testing.T) {
+	tmpPath, err := os.MkdirTemp("", ".folderwatcher_test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpPath)
+	quitChan := make(chan struct{})
+
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g0"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g1"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g2"), os.ModePerm)
+
+	filesIn := []string{"A", "B", "C"}
+	var filesOut []string
+
+	wg := sync.WaitGroup{}
+
+	conf := Config{
+		Folder: filepath.Join(tmpPath, "*"),
+	}
+
+	watcher, err := NewFolderWatcher(conf, true, quitChan)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	go watcher.Watch(func(filePath string) (bool, error) {
+		if !filepath.IsAbs(filePath) {
+			t.Errorf("file %s is not an absolute path", filePath)
+		}
+		rel, err := filepath.Rel(tmpPath, filePath)
+		if err != nil {
+			return true, err
+		}
+		filesOut = append(filesOut, rel)
+		wg.Done()
+		return true, nil
+	}, func(s string, err error) {
+	})
+
+	for i, f := range filesIn {
+		wg.Add(1)
+		_ = os.WriteFile(filepath.Join(tmpPath, "g"+strconv.Itoa(i), f), []byte{0}, os.ModePerm)
+	}
+
+	finishedChan := make(chan struct{})
+	go func() {
+		wg.Wait()
+		finishedChan <- struct{}{}
+	}()
+
+	ctx, ctxCancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer ctxCancel()
+
+	select {
+	case <-finishedChan:
+	case <-ctx.Done():
+		t.Error(ctx.Err())
+	}
+	quitChan <- struct{}{}
+
+	if len(filesOut) != len(filesIn) {
+		t.Errorf("filesOut length %d != %d", len(filesOut), len(filesIn))
+	}
+	for i, f := range filesIn {
+		if !Contains(filesOut, filepath.Join("g"+strconv.Itoa(i), f)) {
+			t.Errorf("File %s not found in %s", f, filesOut)
+		}
+	}
+}
+
+func TestGlobbingN2(t *testing.T) {
+	tmpPath, err := os.MkdirTemp("", ".folderwatcher_test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpPath)
+	quitChan := make(chan struct{})
+
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g0", "s0"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g0", "s2"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g1", "s1"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "g1", "s3"), os.ModePerm)
+	_ = os.MkdirAll(filepath.Join(tmpPath, "gX"), os.ModePerm)
+
+	filesIn := []string{"A", "B", "C", "D"}
+	var filesOut []string
+
+	wg := sync.WaitGroup{}
+
+	conf := Config{
+		Folder: filepath.Join(tmpPath, "*", "*"),
+	}
+
+	watcher, err := NewFolderWatcher(conf, true, quitChan)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	go watcher.Watch(func(filePath string) (bool, error) {
+		if !filepath.IsAbs(filePath) {
+			t.Errorf("file %s is not an absolute path", filePath)
+		}
+		rel, err := filepath.Rel(tmpPath, filePath)
+		if err != nil {
+			return true, err
+		}
+		filesOut = append(filesOut, rel)
+		wg.Done()
+		return true, nil
+	}, func(s string, err error) {
+	})
+
+	for i, f := range filesIn {
+		wg.Add(1)
+		_ = os.WriteFile(filepath.Join(tmpPath, "g"+strconv.Itoa(i%2), "s"+strconv.Itoa(i), f), []byte{0}, os.ModePerm)
+	}
+
+	wg.Add(1)
+	_ = os.WriteFile(filepath.Join(tmpPath, "gX", "foo"), []byte{0}, os.ModePerm)
+
+	finishedChan := make(chan struct{})
+	go func() {
+		wg.Wait()
+		finishedChan <- struct{}{}
+	}()
+
+	ctx, ctxCancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer ctxCancel()
+
+	select {
+	case <-finishedChan:
+	case <-ctx.Done():
+		wg.Done() // ctx Will Timeout, because gX/foo will always be remaining
+		// t.Error(ctx.Err())
+	}
+	quitChan <- struct{}{}
+
+	if len(filesOut) != len(filesIn) {
+		t.Errorf("filesOut length %d != %d", len(filesOut), len(filesIn))
+	}
+	for i, f := range filesIn {
+		if !Contains(filesOut, filepath.Join("g"+strconv.Itoa(i%2), "s"+strconv.Itoa(i), f)) {
+			t.Errorf("File %s not found in %s", f, filesOut)
+		}
+	}
+	if Contains(filesOut, filepath.Join("gX", "foo")) {
+		t.Errorf("File %s found in %s", filepath.Join("gX", "foo"), filesOut)
+	}
+}
diff --git a/folderwatcher_oldFilesInOrder_test.go b/folderwatcher_oldFilesInOrder_test.go
new file mode 100644
index 0000000..da7bd1e
--- /dev/null
+++ b/folderwatcher_oldFilesInOrder_test.go
@@ -0,0 +1,87 @@
+package folderwatcher
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+	"time"
+)
+
+func TestOldFilesInCreationOrder(t *testing.T) {
+	tmpPath, err := os.MkdirTemp("", ".folderwatcher_test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpPath)
+	quitChan := make(chan struct{})
+
+	filesIn := []string{"2", "C", "B", "A", "1"}
+	makeAbsFilePaths(t, tmpPath, &filesIn)
+	var filesOut []string
+
+	wg := sync.WaitGroup{}
+
+	conf := Config{
+		Folder: tmpPath,
+	}
+
+	for _, f := range filesIn {
+		wg.Add(1)
+		_ = os.WriteFile(f, []byte{0}, os.ModePerm)
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	watcher, err := NewFolderWatcher(conf, true, quitChan)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	go watcher.Watch(func(filePath string) (bool, error) {
+		if !filepath.IsAbs(filePath) {
+			t.Errorf("file %s is not an absolute path", filePath)
+		}
+		filesOut = append(filesOut, filePath)
+		wg.Done()
+		return true, nil
+	}, func(s string, err error) {
+	})
+
+	finishedChan := make(chan struct{})
+	go func() {
+		wg.Wait()
+		finishedChan <- struct{}{}
+	}()
+
+	ctx, ctxCancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer ctxCancel()
+
+	select {
+	case <-finishedChan:
+	case <-ctx.Done():
+		t.Error(ctx.Err())
+	}
+	quitChan <- struct{}{}
+
+	if len(filesOut) != len(filesIn) {
+		t.Errorf("filesOut length %d != %d", len(filesOut), len(filesIn))
+	}
+
+	filesInS := fmt.Sprintf("%s", filesIn)
+	filesOutS := fmt.Sprintf("%s", filesOut)
+	if filesInS != filesOutS {
+		t.Errorf("filesIn != filesOut %s != %s", filesIn, filesOut)
+	}
+}
+
+func makeAbsFilePaths(t *testing.T, rootPath string, filesIn *[]string) {
+	t.Helper()
+	for i, f := range *filesIn { //remap filesIn to Full Path
+		(*filesIn)[i] = filepath.Join(rootPath, f)
+		if !filepath.IsAbs((*filesIn)[i]) {
+			t.Fatalf("file %s is not an absolute path", (*filesIn)[i])
+		}
+	}
+}
diff --git a/folderwatcher_test.go b/folderwatcher_test.go
index ab842ed..6e3543a 100644
--- a/folderwatcher_test.go
+++ b/folderwatcher_test.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"os"
 	"path/filepath"
-	"strconv"
 	"sync"
 	"testing"
 	"time"
@@ -314,157 +313,6 @@ func TestOldAndNewFileHandlingWithoutExisting(t *testing.T) {
 	}
 }
 
-func TestGlobbingN1(t *testing.T) {
-	tmpPath, err := os.MkdirTemp("", ".folderwatcher_test")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(tmpPath)
-	quitChan := make(chan struct{})
-
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g0"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g1"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g2"), os.ModePerm)
-
-	filesIn := []string{"A", "B", "C"}
-	var filesOut []string
-
-	wg := sync.WaitGroup{}
-
-	conf := Config{
-		Folder: filepath.Join(tmpPath, "*"),
-	}
-
-	watcher, err := NewFolderWatcher(conf, true, quitChan)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	go watcher.Watch(func(filePath string) (bool, error) {
-		if !filepath.IsAbs(filePath) {
-			t.Errorf("file %s is not an absolute path", filePath)
-		}
-		rel, err := filepath.Rel(tmpPath, filePath)
-		if err != nil {
-			return true, err
-		}
-		filesOut = append(filesOut, rel)
-		wg.Done()
-		return true, nil
-	}, func(s string, err error) {
-	})
-
-	for i, f := range filesIn {
-		wg.Add(1)
-		_ = os.WriteFile(filepath.Join(tmpPath, "g"+strconv.Itoa(i), f), []byte{0}, os.ModePerm)
-	}
-
-	finishedChan := make(chan struct{})
-	go func() {
-		wg.Wait()
-		finishedChan <- struct{}{}
-	}()
-
-	ctx, ctxCancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer ctxCancel()
-
-	select {
-	case <-finishedChan:
-	case <-ctx.Done():
-		t.Error(ctx.Err())
-	}
-	quitChan <- struct{}{}
-
-	if len(filesOut) != len(filesIn) {
-		t.Errorf("filesOut length %d != %d", len(filesOut), len(filesIn))
-	}
-	for i, f := range filesIn {
-		if !Contains(filesOut, filepath.Join("g"+strconv.Itoa(i), f)) {
-			t.Errorf("File %s not found in %s", f, filesOut)
-		}
-	}
-}
-
-func TestGlobbingN2(t *testing.T) {
-	tmpPath, err := os.MkdirTemp("", ".folderwatcher_test")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(tmpPath)
-	quitChan := make(chan struct{})
-
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g0", "s0"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g0", "s2"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g1", "s1"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "g1", "s3"), os.ModePerm)
-	_ = os.MkdirAll(filepath.Join(tmpPath, "gX"), os.ModePerm)
-
-	filesIn := []string{"A", "B", "C", "D"}
-	var filesOut []string
-
-	wg := sync.WaitGroup{}
-
-	conf := Config{
-		Folder: filepath.Join(tmpPath, "*", "*"),
-	}
-
-	watcher, err := NewFolderWatcher(conf, true, quitChan)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	go watcher.Watch(func(filePath string) (bool, error) {
-		if !filepath.IsAbs(filePath) {
-			t.Errorf("file %s is not an absolute path", filePath)
-		}
-		rel, err := filepath.Rel(tmpPath, filePath)
-		if err != nil {
-			return true, err
-		}
-		filesOut = append(filesOut, rel)
-		wg.Done()
-		return true, nil
-	}, func(s string, err error) {
-	})
-
-	for i, f := range filesIn {
-		wg.Add(1)
-		_ = os.WriteFile(filepath.Join(tmpPath, "g"+strconv.Itoa(i%2), "s"+strconv.Itoa(i), f), []byte{0}, os.ModePerm)
-	}
-
-	wg.Add(1)
-	_ = os.WriteFile(filepath.Join(tmpPath, "gX", "foo"), []byte{0}, os.ModePerm)
-
-	finishedChan := make(chan struct{})
-	go func() {
-		wg.Wait()
-		finishedChan <- struct{}{}
-	}()
-
-	ctx, ctxCancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer ctxCancel()
-
-	select {
-	case <-finishedChan:
-	case <-ctx.Done():
-		wg.Done() // ctx Will Timeout, because gX/foo will always be remaining
-		// t.Error(ctx.Err())
-	}
-	quitChan <- struct{}{}
-
-	if len(filesOut) != len(filesIn) {
-		t.Errorf("filesOut length %d != %d", len(filesOut), len(filesIn))
-	}
-	for i, f := range filesIn {
-		if !Contains(filesOut, filepath.Join("g"+strconv.Itoa(i%2), "s"+strconv.Itoa(i), f)) {
-			t.Errorf("File %s not found in %s", f, filesOut)
-		}
-	}
-	if Contains(filesOut, filepath.Join("gX", "foo")) {
-		t.Errorf("File %s found in %s", filepath.Join("gX", "foo"), filesOut)
-	}
-}
-
 func Contains[T comparable](slice []T, item T) bool {
 	for _, v := range slice {
 		if v == item {