From 36e184266f76580e0e2b517512102548e4ed72bf Mon Sep 17 00:00:00 2001
From: Max Sum <max@lolyculture.com>
Date: Sun, 1 Dec 2019 00:35:52 +0800
Subject: [PATCH] union: fix description and variable names of epff, epmfs, mfs
 policies

---
 backend/union/policy/epff.go  | 28 ++++++++++++++--------------
 backend/union/policy/epmfs.go | 19 +++++++++++--------
 backend/union/policy/mfs.go   |  8 +++++---
 3 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/backend/union/policy/epff.go b/backend/union/policy/epff.go
index 2da8b3f5a..16589fe81 100644
--- a/backend/union/policy/epff.go
+++ b/backend/union/policy/epff.go
@@ -17,19 +17,19 @@ type EpFF struct {}
 
 func (p *EpFF) epff(ctx context.Context, upstreams []*upstream.Fs, path string) (*upstream.Fs, error) {
 	ch := make(chan *upstream.Fs)
-	for _, r := range upstreams {
-		r := r // Closure
+	for _, u := range upstreams {
+		u := u // Closure
 		go func() {
-			if !exists(ctx, r, path) {
-				r = nil
+			if !exists(ctx, u, path) {
+				u = nil
 			}
-			ch <- r
+			ch <- u
 		}()
 	}
-	var r *upstream.Fs
+	var u *upstream.Fs
 	for i := 0; i < len(upstreams); i++ {
-		r = <- ch
-		if r != nil {
+		u = <- ch
+		if u != nil {
 			// close remaining goroutines
 			go func(num int) {
 				defer close(ch)
@@ -39,10 +39,10 @@ func (p *EpFF) epff(ctx context.Context, upstreams []*upstream.Fs, path string)
 			}(len(upstreams) - 1 - i)
 		}
 	}
-	if r == nil {
+	if u == nil {
 		return nil, fs.ErrorObjectNotFound
 	}
-	return r, nil
+	return u, nil
 }
 
 // Action category policy, governing the modification of files and directories
@@ -54,8 +54,8 @@ func (p *EpFF) Action(ctx context.Context, upstreams []*upstream.Fs, path string
 	if len(upstreams) == 0 {
 		return nil, fs.ErrorPermissionDenied
 	}
-	r, err := p.epff(ctx, upstreams, path)
-	return []*upstream.Fs{r}, err
+	u, err := p.epff(ctx, upstreams, path)
+	return []*upstream.Fs{u}, err
 }
 
 // ActionEntries is ACTION category policy but receving a set of candidate entries
@@ -79,8 +79,8 @@ func (p *EpFF) Create(ctx context.Context, upstreams []*upstream.Fs, path string
 	if len(upstreams) == 0 {
 		return nil, fs.ErrorPermissionDenied
 	}
-	r, err := p.epff(ctx, upstreams, path)
-	return []*upstream.Fs{r}, err
+	u, err := p.epff(ctx, upstreams, path)
+	return []*upstream.Fs{u}, err
 }
 
 // CreateEntries is CREATE category policy but receving a set of candidate entries
diff --git a/backend/union/policy/epmfs.go b/backend/union/policy/epmfs.go
index 4693c8e9a..c9e69ca1b 100644
--- a/backend/union/policy/epmfs.go
+++ b/backend/union/policy/epmfs.go
@@ -12,7 +12,7 @@ func init(){
 }
 
 // EpMfs stands for existing path, most free space
-// Of all the branches on which the path exists choose the drive with the most free space.
+// Of all the candidates on which the path exists choose the one with the most free space.
 type EpMfs struct {
 	EpAll
 }
@@ -20,16 +20,19 @@ type EpMfs struct {
 func (p *EpMfs) mfs(upstreams []*upstream.Fs) (*upstream.Fs, error) {
 	var maxFreeSpace int64
 	var mfsupstream *upstream.Fs
-	for _, r := range upstreams {
-		space, err := r.GetFreeSpace()
+	for _, u := range upstreams {
+		space, err := u.GetFreeSpace()
 		if err != nil {
 			return nil, err
 		}
 		if maxFreeSpace < space {
 			maxFreeSpace = space
-			mfsupstream = r
+			mfsupstream = u
 		}
 	}
+	if mfsupstream == nil {
+		return nil, fs.ErrorObjectNotFound
+	}
 	return mfsupstream, nil
 }
 
@@ -55,8 +58,8 @@ func (p *EpMfs) Action(ctx context.Context, upstreams []*upstream.Fs, path strin
 	if err != nil {
 		return nil, err
 	}
-	r, err := p.mfs(upstreams)
-	return []*upstream.Fs{r}, err
+	u, err := p.mfs(upstreams)
+	return []*upstream.Fs{u}, err
 }
 
 // ActionEntries is ACTION category policy but receving a set of candidate entries
@@ -75,8 +78,8 @@ func (p *EpMfs) Create(ctx context.Context, upstreams []*upstream.Fs, path strin
 	if err != nil {
 		return nil, err
 	}
-	r, err := p.mfs(upstreams)
-	return []*upstream.Fs{r}, err
+	u, err := p.mfs(upstreams)
+	return []*upstream.Fs{u}, err
 }
 
 // CreateEntries is CREATE category policy but receving a set of candidate entries
diff --git a/backend/union/policy/mfs.go b/backend/union/policy/mfs.go
index 3143ca2ec..bc4cca5d9 100644
--- a/backend/union/policy/mfs.go
+++ b/backend/union/policy/mfs.go
@@ -12,7 +12,9 @@ func init(){
 }
 
 // Mfs stands for most free space
-// Of all the candidates on which the path exists choose the one with the most free space.
+// Search category: same as epmfs.
+// Action category: same as epmfs.
+// Create category: Pick the drive with the most free space.
 type Mfs struct {
 	EpMfs
 }
@@ -26,6 +28,6 @@ func (p *Mfs) Create(ctx context.Context, upstreams []*upstream.Fs, path string)
 	if len(upstreams) == 0 {
 		return nil, fs.ErrorPermissionDenied
 	}
-	r, err := p.mfs(upstreams)
-	return []*upstream.Fs{r}, err
+	u, err := p.mfs(upstreams)
+	return []*upstream.Fs{u}, err
 }