[hotfix] Add a log of download file time for RemoteLogDownloader (#1052)

Author: swuferhong

fluss-client/src/main/java/com/alibaba/fluss/client/table/scanner/batch/KvSnapshotBatchScanner.java

@@ -195,10 +195,15 @@ private void initReaderAsynchronously() {
                                         LOG.info(
                                                 "Start to download kv snapshot files to local directory for bucket {}.",
                                                 tableBucket);
+                                        long startTime = System.currentTimeMillis();
                                         remoteFileDownloader.transferAllToDirectory(
                                                 fsPathAndFileNames,
                                                 snapshotLocalDirectory,
                                                 closeableRegistry);
+                                        LOG.info(
+                                                "Download kv snapshot files to local directory for bucket {} cost {} ms.",
+                                                tableBucket,
+                                                System.currentTimeMillis() - startTime);
                                         snapshotFilesReader =
                                                 new SnapshotFilesReader(
                                                         kvFormat,

fluss-client/src/main/java/com/alibaba/fluss/client/table/scanner/log/RemoteLogDownloader.java

@@ -158,10 +158,15 @@ void fetchOnce() throws Exception {
             LOG.info(
                     "Start to download remote log segment file {} to local.",
                     fsPathAndFileName.getFileName());
+            long startTime = System.currentTimeMillis();
             remoteFileDownloader.transferAllToDirectory(
                     Collections.singletonList(fsPathAndFileName),
                     segmentPath,
                     new CloseableRegistry());
+            LOG.info(
+                    "Download remote log segment file {} to local cost {} ms.",
+                    fsPathAndFileName.getFileName(),
+                    System.currentTimeMillis() - startTime);
             File localFile = new File(segmentPath.toFile(), fsPathAndFileName.getFileName());
             scannerMetricGroup.remoteFetchBytes().inc(localFile.length());
             String segmentId = request.segment.remoteLogSegmentId().toString();