From 3552de49ead229bb8ced77c87d4530e3c3e3eb03 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Mon, 30 Jan 2017 01:53:29 +0300
Subject: [PATCH] Added comment; fixed uninitialized read [#CLICKHOUSE-20227].

---
 dbms/include/DB/IO/WriteBufferFromHTTPServerResponse.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dbms/include/DB/IO/WriteBufferFromHTTPServerResponse.h b/dbms/include/DB/IO/WriteBufferFromHTTPServerResponse.h
index 75ec990e8e3..a3cbdfeb9a9 100644
--- a/dbms/include/DB/IO/WriteBufferFromHTTPServerResponse.h
+++ b/dbms/include/DB/IO/WriteBufferFromHTTPServerResponse.h
@@ -36,13 +36,17 @@ namespace ErrorCodes
 ///
 /// Additionally, supports HTTP response compression (in this case corresponding Content-Encoding
 /// header will be set).
+///
+/// Also this class write and flush special X-ClickHouse-Progress HTTP headers
+///  if no data was sent at the time of progress notification.
+/// This allows to implement progress bar in HTTP clients.
 class WriteBufferFromHTTPServerResponse : public BufferWithOwnMemory<WriteBuffer>
 {
 private:
 	Poco::Net::HTTPServerResponse & response;
 
-	bool add_cors_header;
-	bool compress;
+	bool add_cors_header = false;
+	bool compress = false;
 	ZlibCompressionMethod compression_method;
 	int compression_level = Z_DEFAULT_COMPRESSION;