1 files changed, 94 insertions, 0 deletions
diff --git a/weed/pb/filer_pb_tail.go b/weed/pb/filer_pb_tail.go
new file mode 100644
index 000000000..31fb62fb3
--- /dev/null
+++ b/weed/pb/filer_pb_tail.go
@@ -0,0 +1,94 @@
+package pb
+
+import (
+	"context"
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"google.golang.org/grpc"
+	"io"
+	"time"
+)
+
+type ProcessMetadataFunc func(resp *filer_pb.SubscribeMetadataResponse) error
+
+func FollowMetadata(filerAddress string, grpcDialOption grpc.DialOption,
+	clientName string, pathPrefix string, lastTsNs int64, selfSignature int32,
+	processEventFn ProcessMetadataFunc, fatalOnError bool) error {
+
+	err := WithFilerClient(filerAddress, grpcDialOption, makeFunc(
+		clientName, pathPrefix, lastTsNs, selfSignature, processEventFn, fatalOnError))
+	if err != nil {
+		return fmt.Errorf("subscribing filer meta change: %v", err)
+	}
+	return err
+}
+
+func WithFilerClientFollowMetadata(filerClient filer_pb.FilerClient,
+	clientName string, pathPrefix string, lastTsNs int64, selfSignature int32,
+	processEventFn ProcessMetadataFunc, fatalOnError bool) error {
+
+	err := filerClient.WithFilerClient(makeFunc(
+		clientName, pathPrefix, lastTsNs, selfSignature, processEventFn, fatalOnError))
+	if err != nil {
+		return fmt.Errorf("subscribing filer meta change: %v", err)
+	}
+
+	return nil
+}
+
+func makeFunc(clientName string, pathPrefix string, lastTsNs int64, selfSignature int32,
+	processEventFn ProcessMetadataFunc, fatalOnError bool) func(client filer_pb.SeaweedFilerClient) error {
+	return func(client filer_pb.SeaweedFilerClient) error {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		stream, err := client.SubscribeMetadata(ctx, &filer_pb.SubscribeMetadataRequest{
+			ClientName: clientName,
+			PathPrefix: pathPrefix,
+			SinceNs:    lastTsNs,
+			Signature:  selfSignature,
+		})
+		if err != nil {
+			return fmt.Errorf("subscribe: %v", err)
+		}
+
+		for {
+			resp, listenErr := stream.Recv()
+			if listenErr == io.EOF {
+				return nil
+			}
+			if listenErr != nil {
+				return listenErr
+			}
+
+			if err := processEventFn(resp); err != nil {
+				if fatalOnError {
+					glog.Fatalf("process %v: %v", resp, err)
+				} else {
+					glog.Errorf("process %v: %v", resp, err)
+				}
+			}
+			lastTsNs = resp.TsNs
+		}
+	}
+}
+
+func AddOffsetFunc(processEventFn ProcessMetadataFunc, offsetInterval time.Duration, offsetFunc func(counter int64, offset int64) error) ProcessMetadataFunc {
+	var counter int64
+	var lastWriteTime time.Time
+	return func(resp *filer_pb.SubscribeMetadataResponse) error {
+		if err := processEventFn(resp); err != nil {
+			return err
+		}
+		counter++
+		if lastWriteTime.Add(offsetInterval).Before(time.Now()) {
+			counter = 0
+			lastWriteTime = time.Now()
+			if err := offsetFunc(counter, resp.TsNs); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+}