WIP

weed/server/volume_grpc_follow.go

@@ -0,0 +1,53 @@
+package weed_server
+
+import (
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
+	"io"
+	"os"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/volume_server_pb"
+	"github.com/chrislusf/seaweedfs/weed/storage"
+)
+
+func (vs *VolumeServer) VolumeFollow(req *volume_server_pb.VolumeFollowRequest, stream volume_server_pb.VolumeServer_VolumeFollowServer) error {
+
+	v := vs.store.GetVolume(storage.VolumeId(req.VolumeId))
+	if v == nil {
+		return fmt.Errorf("not found volume id %d", req.VolumeId)
+	}
+
+	stopOffset := v.Size()
+	foundOffset, isLastOne, err := v.BinarySearchByAppendAtNs(req.Since)
+	if err != nil {
+		return fmt.Errorf("fail to locate by appendAtNs: %s", err)
+	}
+
+	if isLastOne {
+		return nil
+	}
+
+	startOffset := int64(foundOffset) * int64(types.NeedleEntrySize)
+
+	buf := make([]byte, 1024*1024*2)
+	return sendFileContent(v.DataFile(), buf, startOffset, stopOffset, stream)
+
+}
+
+func sendFileContent(datFile *os.File, buf []byte, startOffset, stopOffset int64, stream volume_server_pb.VolumeServer_VolumeFollowServer) error {
+	var blockSizeLimit = int64(len(buf))
+	for i := int64(0); i < stopOffset-startOffset; i += blockSizeLimit {
+		n, readErr := datFile.ReadAt(buf, startOffset+i)
+		if readErr == nil || readErr == io.EOF {
+			resp := &volume_server_pb.VolumeFollowResponse{}
+			resp.FileContent = buf[i : i+int64(n)]
+			sendErr := stream.Send(resp)
+			if sendErr != nil {
+				return sendErr
+			}
+		} else {
+			return readErr
+		}
+	}
+	return nil
+}