3 files changed, 37 insertions, 10 deletions
diff --git a/weed/server/filer_server_handlers_read.go b/weed/server/filer_server_handlers_read.go
index b59780632..96fc38bf5 100644
--- a/weed/server/filer_server_handlers_read.go
+++ b/weed/server/filer_server_handlers_read.go
@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/chrislusf/seaweedfs/weed/filer2"
 	"github.com/chrislusf/seaweedfs/weed/glog"
@@ -78,8 +79,26 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request,
 		w.Header().Set("Content-Type", mimeType)
 	}
 
+	// if modified since
+	if !entry.Attr.Mtime.IsZero() {
+		w.Header().Set("Last-Modified", entry.Attr.Mtime.UTC().Format(http.TimeFormat))
+		if r.Header.Get("If-Modified-Since") != "" {
+			if t, parseError := time.Parse(http.TimeFormat, r.Header.Get("If-Modified-Since")); parseError == nil {
+				if t.After(entry.Attr.Mtime) {
+					w.WriteHeader(http.StatusNotModified)
+					return
+				}
+			}
+		}
+	}
+
 	// set etag
-	setEtag(w, filer2.ETag(entry.Chunks))
+	etag := filer2.ETagEntry(entry)
+	if inm := r.Header.Get("If-None-Match"); inm == "\""+etag+"\"" {
+		w.WriteHeader(http.StatusNotModified)
+		return
+	}
+	setEtag(w, etag)
 
 	if r.Method == "HEAD" {
 		w.Header().Set("Content-Length", strconv.FormatInt(int64(filer2.TotalSize(entry.Chunks)), 10))
diff --git a/weed/server/filer_server_handlers_write.go b/weed/server/filer_server_handlers_write.go
index c3cb48ce7..33e6ee043 100644
--- a/weed/server/filer_server_handlers_write.go
+++ b/weed/server/filer_server_handlers_write.go
@@ -122,12 +122,12 @@ func (fs *FilerServer) PostHandler(w http.ResponseWriter, r *http.Request) {
 	glog.V(4).Infof("write %s to %v", r.URL.Path, urlLocation)
 
 	u, _ := url.Parse(urlLocation)
-	ret, err := fs.uploadToVolumeServer(r, u, auth, w, fileId)
+	ret, md5value, err := fs.uploadToVolumeServer(r, u, auth, w, fileId)
 	if err != nil {
 		return
 	}
 
-	if err = fs.updateFilerStore(ctx, r, w, replication, collection, ret, fileId, ttlSeconds); err != nil {
+	if err = fs.updateFilerStore(ctx, r, w, replication, collection, ret, md5value, fileId, ttlSeconds); err != nil {
 		return
 	}
 
@@ -144,8 +144,8 @@ func (fs *FilerServer) PostHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 // update metadata in filer store
-func (fs *FilerServer) updateFilerStore(ctx context.Context, r *http.Request, w http.ResponseWriter,
-	replication string, collection string, ret *operation.UploadResult, fileId string, ttlSeconds int32) (err error) {
+func (fs *FilerServer) updateFilerStore(ctx context.Context, r *http.Request, w http.ResponseWriter, replication string,
+	collection string, ret *operation.UploadResult, md5value []byte, fileId string, ttlSeconds int32) (err error) {
 
 	stats.FilerRequestCounter.WithLabelValues("postStoreWrite").Inc()
 	start := time.Now()
@@ -186,6 +186,7 @@ func (fs *FilerServer) updateFilerStore(ctx context.Context, r *http.Request, w
 			Collection:  collection,
 			TtlSec:      ttlSeconds,
 			Mime:        ret.Mime,
+			Md5:         md5value,
 		},
 		Chunks: []*filer_pb.FileChunk{{
 			FileId: fileId,
@@ -212,15 +213,15 @@ func (fs *FilerServer) updateFilerStore(ctx context.Context, r *http.Request, w
 }
 
 // send request to volume server
-func (fs *FilerServer) uploadToVolumeServer(r *http.Request, u *url.URL, auth security.EncodedJwt, w http.ResponseWriter, fileId string) (ret *operation.UploadResult, err error) {
+func (fs *FilerServer) uploadToVolumeServer(r *http.Request, u *url.URL, auth security.EncodedJwt, w http.ResponseWriter, fileId string) (ret *operation.UploadResult, md5value []byte, err error) {
 
 	stats.FilerRequestCounter.WithLabelValues("postUpload").Inc()
 	start := time.Now()
 	defer func() { stats.FilerRequestHistogram.WithLabelValues("postUpload").Observe(time.Since(start).Seconds()) }()
 
 	ret = &operation.UploadResult{}
-	hash := md5.New()
-	var body = ioutil.NopCloser(io.TeeReader(r.Body, hash))
+	md5Hash := md5.New()
+	var body = ioutil.NopCloser(io.TeeReader(r.Body, md5Hash))
 
 	request := &http.Request{
 		Method:        r.Method,
@@ -285,7 +286,8 @@ func (fs *FilerServer) uploadToVolumeServer(r *http.Request, u *url.URL, auth se
 		}
 	}
 	// use filer calculated md5 ETag, instead of the volume server crc ETag
-	ret.ETag = fmt.Sprintf("%x", hash.Sum(nil))
+	md5value = md5Hash.Sum(nil)
+	ret.ETag = fmt.Sprintf("%x", md5value)
 	return
 }
 
diff --git a/weed/server/filer_server_handlers_write_autochunk.go b/weed/server/filer_server_handlers_write_autochunk.go
index e70826b5d..d86530bb8 100644
--- a/weed/server/filer_server_handlers_write_autochunk.go
+++ b/weed/server/filer_server_handlers_write_autochunk.go
@@ -2,7 +2,9 @@ package weed_server
 
 import (
 	"context"
+	"crypto/md5"
 	"io"
+	"io/ioutil"
 	"net/http"
 	"path"
 	"strconv"
@@ -91,10 +93,13 @@ func (fs *FilerServer) doAutoChunk(ctx context.Context, w http.ResponseWriter, r
 
 	var fileChunks []*filer_pb.FileChunk
 
+	md5Hash := md5.New()
+	var partReader = ioutil.NopCloser(io.TeeReader(part1, md5Hash))
+
 	chunkOffset := int64(0)
 
 	for chunkOffset < contentLength {
-		limitedReader := io.LimitReader(part1, int64(chunkSize))
+		limitedReader := io.LimitReader(partReader, int64(chunkSize))
 
 		// assign one file id for one chunk
 		fileId, urlLocation, auth, assignErr := fs.assignNewFileInfo(w, r, replication, collection, dataCenter, ttlString)
@@ -157,6 +162,7 @@ func (fs *FilerServer) doAutoChunk(ctx context.Context, w http.ResponseWriter, r
 			Collection:  collection,
 			TtlSec:      ttlSec,
 			Mime:        contentType,
+			Md5:         md5Hash.Sum(nil),
 		},
 		Chunks: fileChunks,
 	}