fix(storage/append): Report progress for appends.

storage/client_test.go

@@ -1000,13 +1000,23 @@ func TestOpenAppendableWriterMultipleFlushesEmulated(t *testing.T) {
 		w.Append = true
 		// This should chunk the request into three separate flushes to storage.
 		w.ChunkSize = MiB
+		var lastReportedOffset int64
+		w.ProgressFunc = func(offset int64) {
+			if offset != lastReportedOffset+MiB {
+				t.Errorf("incorrect progress report: got %d; want %d", offset, lastReportedOffset+MiB)
+			}
+			lastReportedOffset = offset
+		}
 		_, err = w.Write(randomBytes3MiB)
 		if err != nil {
 			t.Fatalf("writing test data: got %v; want ok", err)
 		}
 		if err := w.Close(); err != nil {
 			t.Fatalf("closing test data writer: got %v; want ok", err)
 		}
+		if lastReportedOffset != 3*MiB {
+			t.Errorf("incorrect final progress report: got %d; want %d", lastReportedOffset, 3*MiB)
+		}
 
 		if diff := cmp.Diff(w.Attrs().Name, objName); diff != "" {
 			t.Fatalf("Resulting object name: got(-), want(+):\n%s", diff)

storage/grpc_writer.go

@@ -39,6 +39,7 @@ type gRPCAppendBidiWriteBufferSender struct {
 	objectChecksums *storagepb.ObjectChecksums
 
 	forceFirstMessage bool
+	progress          func(int64)
 	flushOffset       int64
 
 	// Fields used to report responses from the receive side of the stream
@@ -62,6 +63,7 @@ func (w *gRPCWriter) newGRPCAppendBidiWriteBufferSender() (*gRPCAppendBidiWriteB
 		},
 		objectChecksums:   toProtoChecksums(w.sendCRC32C, w.attrs),
 		forceFirstMessage: true,
+		progress:          w.progress,
 	}
 	return s, nil
 }
@@ -246,26 +248,35 @@ func (s *gRPCAppendBidiWriteBufferSender) sendOnConnectedStream(buf []byte, offs
 		if s.recvErr != io.EOF {
 			return nil, s.recvErr
 		}
+		if obj.GetSize() > s.flushOffset {
+			s.flushOffset = obj.GetSize()
+			s.progress(s.flushOffset)
+		}
 		return
 	}
 
 	if flush {
 		// We don't necessarily expect multiple responses for a single flush, but
 		// this allows the server to send multiple responses if it wants to.
-		for s.flushOffset < offset+int64(len(buf)) {
+		flushOffset := s.flushOffset
+		for flushOffset < offset+int64(len(buf)) {
 			resp, ok := <-s.recvs
 			if !ok {
 				return nil, s.recvErr
 			}
 			pSize := resp.GetPersistedSize()
 			rSize := resp.GetResource().GetSize()
-			if s.flushOffset < pSize {
- s.flushOffset = pSize
+			if flushOffset < pSize {
+				flushOffset = pSize
 			}
-			if s.flushOffset < rSize {
- s.flushOffset = rSize
+			if flushOffset < rSize {
+				flushOffset = rSize
 			}
 		}
+		if s.flushOffset < flushOffset {
+			s.flushOffset = flushOffset
+			s.progress(s.flushOffset)
+		}
 	}
 
 	return