[fix](S3FileWriter) Fix boundary issue when multipart upload (#43037)

When the file data size is a multiple of config::s3_write_buffer_size,
number of parts may exceed the actual number of parts that need to be
uploaded. This is because it is incremented by 1 in advance within the
S3FileWriter::appendv method.

be/src/io/fs/s3_file_writer.cpp

@@ -204,12 +204,12 @@ Status S3FileWriter::_build_upload_buffer() {
 Status S3FileWriter::_close_impl() {
     VLOG_DEBUG << "S3FileWriter::close, path: " << _obj_storage_path_opts.path.native();
 
-    if (_cur_part_num == 1 && _pending_buf) {
+    if (_cur_part_num == 1 && _pending_buf) { // data size is less than config::s3_write_buffer_size
         RETURN_IF_ERROR(_set_upload_to_remote_less_than_buffer_size());
     }
 
     if (_bytes_appended == 0) {
-        DCHECK(_cur_part_num == 1);
+        DCHECK_EQ(_cur_part_num, 1);
         // No data written, but need to create an empty file
         RETURN_IF_ERROR(_build_upload_buffer());
         if (!_used_by_s3_committer) {
@@ -220,10 +220,15 @@ Status S3FileWriter::_close_impl() {
         }
     }
 
-    if (_pending_buf != nullptr) {
+    if (_pending_buf != nullptr) { // there is remaining data in buffer need to be uploaded
         _countdown_event.add_count();
         RETURN_IF_ERROR(FileBuffer::submit(std::move(_pending_buf)));
         _pending_buf = nullptr;
+    } else if (_bytes_appended != 0) { // Non-empty file and has nothing to be uploaded
+        // NOTE: When the data size is a multiple of config::s3_write_buffer_size,
+        //       _cur_part_num may exceed the actual number of parts that need to be uploaded.
+        //       This is because it is incremented by 1 in advance within the S3FileWriter::appendv method.
+        _cur_part_num--;
     }
 
     RETURN_IF_ERROR(_complete());
@@ -327,26 +332,29 @@ Status S3FileWriter::_complete() {
     _wait_until_finish("Complete");
     TEST_SYNC_POINT_CALLBACK("S3FileWriter::_complete:1",
                              std::make_pair(&_failed, &_completed_parts));
-    if (!_used_by_s3_committer) { // S3 committer will complete multipart upload file on FE side.
-        if (_failed || _completed_parts.size() != _cur_part_num) {
-            _st = Status::InternalError(
-                    "error status {}, have failed {}, complete parts {}, cur part num {}, whole "
-                    "parts {}, file path {}, file size {}, has left buffer {}",
-                    _st, _failed, _completed_parts.size(), _cur_part_num, _dump_completed_part(),
-                    _obj_storage_path_opts.path.native(), _bytes_appended, _pending_buf != nullptr);
-            LOG(WARNING) << _st;
-            return _st;
-        }
-        // make sure _completed_parts are ascending order
-        std::sort(_completed_parts.begin(), _completed_parts.end(),
-                  [](auto& p1, auto& p2) { return p1.part_num < p2.part_num; });
-        TEST_SYNC_POINT_CALLBACK("S3FileWriter::_complete:2", &_completed_parts);
-        auto resp = client->complete_multipart_upload(_obj_storage_path_opts, _completed_parts);
-        if (resp.status.code != ErrorCode::OK) {
-            LOG_WARNING("Compltet multi part upload failed because {}, file path {}",
-                        resp.status.msg, _obj_storage_path_opts.path.native());
-            return {resp.status.code, std::move(resp.status.msg)};
-        }
+    if (_used_by_s3_committer) {    // S3 committer will complete multipart upload file on FE side.
+        s3_file_created_total << 1; // Assume that it will be created successfully
+        return Status::OK();
+    }
+
+    if (_failed || _completed_parts.size() != _cur_part_num) {
+        _st = Status::InternalError(
+                "error status={} failed={} #complete_parts={} #expected_parts={} "
+                "completed_parts_list={} file_path={} file_size={} has left buffer not uploaded={}",
+                _st, _failed, _completed_parts.size(), _cur_part_num, _dump_completed_part(),
+                _obj_storage_path_opts.path.native(), _bytes_appended, _pending_buf != nullptr);
+        LOG(WARNING) << _st;
+        return _st;
+    }
+    // make sure _completed_parts are ascending order
+    std::sort(_completed_parts.begin(), _completed_parts.end(),
+              [](auto& p1, auto& p2) { return p1.part_num < p2.part_num; });
+    TEST_SYNC_POINT_CALLBACK("S3FileWriter::_complete:2", &_completed_parts);
+    auto resp = client->complete_multipart_upload(_obj_storage_path_opts, _completed_parts);
+    if (resp.status.code != ErrorCode::OK) {
+        LOG_WARNING("Compltet multi part upload failed because {}, file path {}", resp.status.msg,
+                    _obj_storage_path_opts.path.native());
+        return {resp.status.code, std::move(resp.status.msg)};
     }
     s3_file_created_total << 1;
     return Status::OK();