From c014b2e66bb75730891548fb701aa51e3334f6dd Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Wed, 7 Aug 2019 16:40:26 +0100
Subject: [PATCH] rcat: fix slowdown on systems with multiple hashes

Before this fix rclone calculated all the hashes on transfer.  This
was particularly slow for the local backend.

After the fix we just calculate one hash which is enough for data
integrity.
---
 fs/operations/operations.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/operations/operations.go b/fs/operations/operations.go
index ad5d20b0a..81c723174 100644
--- a/fs/operations/operations.go
+++ b/fs/operations/operations.go
@@ -1222,8 +1222,9 @@ func Rcat(ctx context.Context, fdst fs.Fs, dstFileName string, in io.ReadCloser,
 	}()
 	in = tr.Account(in).WithBuffer()
 
-	hashOption := &fs.HashesOption{Hashes: fdst.Hashes()}
-	hash, err := hash.NewMultiHasherTypes(fdst.Hashes())
+	hashes := hash.NewHashSet(fdst.Hashes().GetOne()) // just pick one hash
+	hashOption := &fs.HashesOption{Hashes: hashes}
+	hash, err := hash.NewMultiHasherTypes(hashes)
 	if err != nil {
 		return nil, err
 	}