From e6d6d41f22102e3e6b3f60996e0baec34e3b0432 Mon Sep 17 00:00:00 2001
From: kevinyhzou <kevinyunhe8@gmail.com>
Date: Mon, 22 May 2023 12:23:31 +0800
Subject: [PATCH] minor improve read buffer of hdfs

---
 src/Storages/HDFS/ReadBufferFromHDFS.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/Storages/HDFS/ReadBufferFromHDFS.cpp b/src/Storages/HDFS/ReadBufferFromHDFS.cpp
index ee8e0764db0..fe1c2cc2815 100644
--- a/src/Storages/HDFS/ReadBufferFromHDFS.cpp
+++ b/src/Storages/HDFS/ReadBufferFromHDFS.cpp
@@ -41,6 +41,7 @@ struct ReadBufferFromHDFS::ReadBufferFromHDFSImpl : public BufferWithOwnMemory<S
 
     off_t file_offset = 0;
     off_t read_until_position = 0;
+    off_t file_size;
 
     explicit ReadBufferFromHDFSImpl(
         const std::string & hdfs_uri_,
@@ -63,6 +64,7 @@ struct ReadBufferFromHDFS::ReadBufferFromHDFSImpl : public BufferWithOwnMemory<S
             throw Exception(ErrorCodes::CANNOT_OPEN_FILE,
                 "Unable to open HDFS file: {}. Error: {}",
                 hdfs_uri + hdfs_file_path, std::string(hdfsGetLastError()));
+        file_size = getFileSize();
     }
 
     ~ReadBufferFromHDFSImpl() override
@@ -95,6 +97,10 @@ struct ReadBufferFromHDFS::ReadBufferFromHDFSImpl : public BufferWithOwnMemory<S
         {
             num_bytes_to_read = internal_buffer.size();
         }
+        if (file_size != 0 && file_offset >= file_size)
+        {
+            return false;
+        }
 
         ResourceGuard rlock(read_settings.resource_link, num_bytes_to_read);
         int bytes_read;