refactor: add promises

src/core.go

@@ -8,6 +8,35 @@ import (
 
 type EntrySizeChan chan int64
 
+func ValuePromise[T any](ch chan T) (func(T), func() T) {
+	resolve := func(result T) {
+		ch <- result
+	}
+	value := func() T {
+		return <-ch
+	}
+	return resolve, value
+}
+
+func StatusPromise[T any](ch chan T, err chan error) (func(T), func(error), func() (T, error)) {
+	resolve := func(result T) {
+		ch <- result
+	}
+	reject := func(errValue error) {
+		err <- errValue
+	}
+	status := func() (T, error) {
+		select {
+		case value := <-ch:
+			return value, nil
+		case errValue := <-err:
+			var zero T
+			return zero, errValue
+		}
+	}
+	return resolve, reject, status
+}
+
 func Invoke(folder string) (size int64, e error) {
 	gracefulExit := func(err error) {
 		e = err
@@ -26,40 +55,39 @@ func Invoke(folder string) (size int64, e error) {
 	}
 	errChan := make(chan error)
 	sizeChan := make(EntrySizeChan, entrysLen)
+
+	resolve, reject, status := StatusPromise(sizeChan, errChan)
+
 	for i := 0; i < entrysLen; i++ {
 		go func(entry fs.DirEntry) {
 			if entry.IsDir() {
 				subFolderSize, err := Invoke(path.Join(folder, entry.Name()))
 				if err != nil {
-					gracefulExit(err)
-					errChan <- err
+					reject(err)
 					return
 				}
-				sizeChan <- subFolderSize
+				resolve(subFolderSize)
 				return
 			}
 
 			info, err := entry.Info()
 			if err != nil {
-				gracefulExit(err)
-				errChan <- err
+				reject(err)
 				return
 			}
-			sizeChan <- info.Size()
+			resolve(info.Size())
 		}(entrys[i])
 	}
 
 	for i := 0; i < entrysLen; i++ {
-		select {
-		case nestedErr := <-errChan:
-			gracefulExit(nestedErr)
+		newSize, newErr := status()
+		if newErr != nil {
+			gracefulExit(newErr)
 			return
-		case nestedSize := <-sizeChan:
-			size += nestedSize
 		}
+		size += newSize
 	}
-
-	return size, e
+	return size, nil
 }
 
 func LooseInvoke(folder string) int64 {
@@ -74,24 +102,25 @@ func LooseInvoke(folder string) int64 {
 		return 0
 	}
 	sizeChan := make(EntrySizeChan, entrysLen)
+	resolve, value := ValuePromise(sizeChan)
+
 	for i := 0; i < entrysLen; i++ {
 		go func(entry fs.DirEntry) {
 			if entry.IsDir() {
 				subFolderSize := LooseInvoke(path.Join(folder, entry.Name()))
-				sizeChan <- subFolderSize
+				resolve(subFolderSize)
 				return
 			}
 			info, err := entry.Info()
 			if err != nil {
-				sizeChan <- 0
+				resolve(0)
 				return
 			}
-			sizeChan <- info.Size()
+			resolve(info.Size())
 		}(entrys[i])
 	}
-
 	for i := 0; i < entrysLen; i++ {
-		size += <-sizeChan
+		size += value()
 	}
 	return size
 }