listen for metadata updates

weed/mount/meta_cache/meta_cache_subscribe.go

@@ -0,0 +1,68 @@
+package meta_cache
+
+import (
+	"context"
+	"github.com/chrislusf/seaweedfs/weed/filer"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/util"
+)
+
+func SubscribeMetaEvents(mc *MetaCache, selfSignature int32, client filer_pb.FilerClient, dir string, lastTsNs int64) error {
+
+	processEventFn := func(resp *filer_pb.SubscribeMetadataResponse) error {
+		message := resp.EventNotification
+
+		for _, sig := range message.Signatures {
+			if sig == selfSignature && selfSignature != 0 {
+				return nil
+			}
+		}
+
+		dir := resp.Directory
+		var oldPath util.FullPath
+		var newEntry *filer.Entry
+		if message.OldEntry != nil {
+			oldPath = util.NewFullPath(dir, message.OldEntry.Name)
+			glog.V(4).Infof("deleting %v", oldPath)
+		}
+
+		if message.NewEntry != nil {
+			if message.NewParentPath != "" {
+				dir = message.NewParentPath
+			}
+			key := util.NewFullPath(dir, message.NewEntry.Name)
+			glog.V(4).Infof("creating %v", key)
+			newEntry = filer.FromPbEntry(dir, message.NewEntry)
+		}
+		err := mc.AtomicUpdateEntryFromFiler(context.Background(), oldPath, newEntry)
+		if err == nil {
+			if message.OldEntry != nil && message.NewEntry != nil {
+				oldKey := util.NewFullPath(resp.Directory, message.OldEntry.Name)
+				mc.invalidateFunc(oldKey, message.OldEntry)
+				if message.OldEntry.Name != message.NewEntry.Name {
+					newKey := util.NewFullPath(dir, message.NewEntry.Name)
+					mc.invalidateFunc(newKey, message.NewEntry)
+				}
+			} else if message.OldEntry == nil && message.NewEntry != nil {
+				// no need to invaalidate
+			} else if message.OldEntry != nil && message.NewEntry == nil {
+				oldKey := util.NewFullPath(resp.Directory, message.OldEntry.Name)
+				mc.invalidateFunc(oldKey, message.OldEntry)
+			}
+		}
+
+		return err
+
+	}
+
+	util.RetryForever("followMetaUpdates", func() error {
+		return pb.WithFilerClientFollowMetadata(client, "mount", selfSignature, dir, &lastTsNs, selfSignature, processEventFn, true)
+	}, func(err error) bool {
+		glog.Errorf("follow metadata updates: %v", err)
+		return true
+	})
+
+	return nil
+}