From 69655ba8e56c94cc1ef6fea5420c5a66d8fe650a Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Mon, 9 Aug 2021 22:11:57 -0700
Subject: [PATCH] mount: cache on reading remote storage

---
 weed/filesys/file.go                    | 27 +++++++++++++++++++++++++
 weed/filesys/filehandle.go              | 10 +++++++++
 weed/pb/filer_pb/filer_pb_helper.go     |  4 ++++
 weed/server/filer_grpc_server_remote.go |  2 +-
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/weed/filesys/file.go b/weed/filesys/file.go
index 7f021619c..b990b20d1 100644
--- a/weed/filesys/file.go
+++ b/weed/filesys/file.go
@@ -360,3 +360,30 @@ func (file *File) saveEntry(entry *filer_pb.Entry) error {
 func (file *File) getEntry() *filer_pb.Entry {
 	return file.entry
 }
+
+func (file *File) downloadRemoteEntry(entry *filer_pb.Entry) (*filer_pb.Entry, error) {
+	err := file.wfs.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+
+		request := &filer_pb.DownloadToLocalRequest{
+			Directory: file.dir.FullPath(),
+			Name:      entry.Name,
+		}
+
+		glog.V(4).Infof("download entry: %v", request)
+		resp, err := client.DownloadToLocal(context.Background(), request)
+		if err != nil {
+			glog.Errorf("DownloadToLocal file %s/%s: %v", file.dir.FullPath(), file.Name, err)
+			return fuse.EIO
+		}
+
+		entry = resp.Entry
+
+		file.wfs.metaCache.InsertEntry(context.Background(), filer.FromPbEntry(request.Directory, resp.Entry))
+
+		file.dirtyMetadata = false
+
+		return nil
+	})
+
+	return entry, err
+}
diff --git a/weed/filesys/filehandle.go b/weed/filesys/filehandle.go
index 9acede330..5cd7ca948 100644
--- a/weed/filesys/filehandle.go
+++ b/weed/filesys/filehandle.go
@@ -114,6 +114,16 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, error) {
 		return 0, io.EOF
 	}
 
+	if entry.IsInRemoteOnly() {
+		glog.V(4).Infof("download remote entry %s", fh.f.fullpath())
+		newEntry, err := fh.f.downloadRemoteEntry(entry)
+		if err != nil {
+			glog.V(1).Infof("download remote entry %s: %v", fh.f.fullpath(), err)
+			return 0, err
+		}
+		entry = newEntry
+	}
+
 	fileSize := int64(filer.FileSize(entry))
 	fileFullPath := fh.f.fullpath()
 
diff --git a/weed/pb/filer_pb/filer_pb_helper.go b/weed/pb/filer_pb/filer_pb_helper.go
index ae282db75..7480d469a 100644
--- a/weed/pb/filer_pb/filer_pb_helper.go
+++ b/weed/pb/filer_pb/filer_pb_helper.go
@@ -12,6 +12,10 @@ import (
 	"github.com/viant/ptrie"
 )
 
+func (entry *Entry) IsInRemoteOnly() bool {
+	return len(entry.Chunks) == 0 && entry.RemoteEntry != nil && entry.RemoteEntry.RemoteSize > 0
+}
+
 func ToFileIdObject(fileIdStr string) (*FileId, error) {
 	t, err := needle.ParseFileIdFromString(fileIdStr)
 	if err != nil {
diff --git a/weed/server/filer_grpc_server_remote.go b/weed/server/filer_grpc_server_remote.go
index 9cd3c296b..2cbfd3319 100644
--- a/weed/server/filer_grpc_server_remote.go
+++ b/weed/server/filer_grpc_server_remote.go
@@ -155,7 +155,7 @@ func (fs *FilerServer) DownloadToLocal(ctx context.Context, req *filer_pb.Downlo
 
 	fs.filer.NotifyUpdateEvent(ctx, entry, newEntry, true, false, nil)
 
-	resp.Entry = entry.ToProtoEntry()
+	resp.Entry = newEntry.ToProtoEntry()
 
 	return resp, nil