From 655020509ba3559ca1280f8c1d22c0ecd9e1f88c Mon Sep 17 00:00:00 2001
From: JiahuaChen <garfieldjia@qq.com>
Date: Thu, 17 Mar 2022 15:11:18 +0800
Subject: [PATCH] Fix slog reader doesnt switch file when theres no switch log
 at EOF

---
 .../slog/ob_storage_log_reader.cpp            |  8 +-
 .../slog/test_storage_log_reader_writer.cpp   | 95 ++++++++++++++++++-
 2 files changed, 98 insertions(+), 5 deletions(-)

diff --git a/src/storage/blocksstable/slog/ob_storage_log_reader.cpp b/src/storage/blocksstable/slog/ob_storage_log_reader.cpp
index 5603d8dc16..5d5c4ed0d5 100644
--- a/src/storage/blocksstable/slog/ob_storage_log_reader.cpp
+++ b/src/storage/blocksstable/slog/ob_storage_log_reader.cpp
@@ -437,10 +437,12 @@ int ObStorageLogReader::load_buf()
 int ObStorageLogReader::check_switch_file(const int get_ret, const LogCommand cmd)
 {
   int ret = get_ret;
-  // Check switch file when meet below situation:
-  // 1) Meet switch log command
+  const bool fetch_log_again = (OB_READ_NOTHING == get_ret);
+  // Check switch file when meet below 2 situation:
+  // 1) Meet switch log command, or
+  // 2) read the last log (which may be incomplete and ignored)
   // Otherwise directly ret
-  if (common::OB_SUCCESS == get_ret && OB_LOG_SWITCH_LOG == cmd) {
+  if ((common::OB_SUCCESS == get_ret && OB_LOG_SWITCH_LOG == cmd) || fetch_log_again) {
     STORAGE_REDO_LOG(INFO, "reach the end of log", K_(file_id));
     if (OB_FAIL(close())) {
       STORAGE_REDO_LOG(ERROR, "close error", K(ret));
diff --git a/unittest/storage/blocksstable/slog/test_storage_log_reader_writer.cpp b/unittest/storage/blocksstable/slog/test_storage_log_reader_writer.cpp
index 059e0f3b59..a07597c6d5 100644
--- a/unittest/storage/blocksstable/slog/test_storage_log_reader_writer.cpp
+++ b/unittest/storage/blocksstable/slog/test_storage_log_reader_writer.cpp
@@ -863,9 +863,100 @@ TEST_F(TestStorageLogReaderWriter, seek_to_end)
   ASSERT_EQ(1, cnt);
   ret = reader.get_next_cursor(read_cursor);
   ASSERT_EQ(OB_SUCCESS, ret);
-  ASSERT_EQ(LOG_FILE_ID, read_cursor.file_id_);
+  ASSERT_EQ(LOG_FILE_ID + 1, read_cursor.file_id_);
   ASSERT_EQ(LOG_START_SEQ + 2, read_cursor.log_id_);
-  ASSERT_EQ(4096 * 2, read_cursor.offset_);
+  ASSERT_EQ(0, read_cursor.offset_);
+}
+
+TEST_F(TestStorageLogReaderWriter, read_multiple_files)
+{
+  int ret = OB_SUCCESS;
+  const char LOG_DIR[512] = "./test_storage_log_rw";
+  const int64_t LOG_FILE_SIZE = 64 << 20;  // 64MB
+  const int64_t CONCURRENT_TRANS_CNT = 128;
+  const int64_t LOG_BUFFER_SIZE = 1966080L;  // 1.875MB
+  const int64_t log_cnt_per_file = 10;
+
+  // write part
+  ObLogCursor start_cursor;
+  start_cursor.file_id_ = 1;
+  start_cursor.log_id_ = 1;
+  start_cursor.offset_ = 0;
+
+  char write_data[128] = "this is read multiple files test.";
+  ObBaseStorageLogBuffer log_buf;
+  ret = log_buf.assign(write_data, 1024);
+  ASSERT_EQ(OB_SUCCESS, ret);
+  ret = log_buf.set_pos(strlen(write_data));
+  ASSERT_EQ(OB_SUCCESS, ret);
+
+  ObStorageLogWriter writer;
+  ret = writer.init(LOG_DIR, LOG_FILE_SIZE, LOG_BUFFER_SIZE, CONCURRENT_TRANS_CNT);
+  ASSERT_EQ(OB_SUCCESS, ret);
+  ret = writer.start_log(start_cursor);
+  ASSERT_EQ(OB_SUCCESS, ret);
+  for (int64_t i = 0; i < log_cnt_per_file; ++i) {
+    ret = writer.flush_log(LogCommand::OB_LOG_DUMMY_LOG, log_buf, start_cursor);
+    ASSERT_EQ(OB_SUCCESS, ret);
+  }
+  start_cursor.file_id_ = 2;
+  start_cursor.offset_ = 0;
+  start_cursor.log_id_ = writer.get_cur_cursor().log_id_;
+  writer.destroy();
+
+  // manually switch file
+  ret = writer.init(LOG_DIR, LOG_FILE_SIZE, LOG_BUFFER_SIZE, CONCURRENT_TRANS_CNT);
+  ASSERT_EQ(OB_SUCCESS, ret);
+  ret = writer.start_log(start_cursor);
+  ASSERT_EQ(OB_SUCCESS, ret);
+  for (int64_t i = 0; i < log_cnt_per_file; ++i) {
+    ret = writer.flush_log(LogCommand::OB_LOG_DUMMY_LOG, log_buf, start_cursor);
+    ASSERT_EQ(OB_SUCCESS, ret);
+  }
+  writer.destroy();
+
+  // read part
+  LogCommand cmd = LogCommand::OB_LOG_UNKNOWN;
+  uint64_t seq = 0;
+  int64_t read_len = 0;
+  char *read_data = NULL;
+  ObLogCursor read_cursor;
+
+  ObStorageLogReader reader;
+  ret = reader.init(LOG_DIR, 1, 0);
+  ASSERT_EQ(OB_SUCCESS, ret);
+
+  while (OB_SUCCESS == ret) {
+    // read dummy log
+    ret = reader.read_log(cmd, seq, read_data, read_len);
+  }
+  ASSERT_EQ(OB_READ_NOTHING, ret);
+
+  ret = reader.get_cursor(read_cursor);
+  ASSERT_EQ(OB_SUCCESS, ret);
+
+  ASSERT_EQ(start_cursor.file_id_ + 1, read_cursor.file_id_);
+  ASSERT_EQ(0, read_cursor.offset_);
+  ASSERT_EQ(start_cursor.log_id_ + 1, read_cursor.log_id_);
+  reader.reset();
+
+  // read start from the end of file 1
+  ret = reader.init(LOG_DIR, 1, 21);
+  ASSERT_EQ(OB_SUCCESS, ret);
+
+  while (OB_SUCCESS == ret) {
+    // read dummy log
+    ret = reader.read_log(cmd, seq, read_data, read_len);
+  }
+  ASSERT_EQ(OB_READ_NOTHING, ret);
+
+  ret = reader.get_cursor(read_cursor);
+  ASSERT_EQ(OB_SUCCESS, ret);
+
+  ASSERT_EQ(start_cursor.file_id_ + 1, read_cursor.file_id_);
+  ASSERT_EQ(0, read_cursor.offset_);
+  ASSERT_EQ(start_cursor.log_id_ + 1, read_cursor.log_id_);
+  reader.reset();
 }
 }  // namespace blocksstable
 }  // namespace oceanbase
-- 
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