pread return OB_SUCCESS when read offset is equal to file length.

src/logservice/ob_log_external_storage_handler.cpp

@@ -182,9 +182,12 @@ int ObLogExternalStorageHandler::pread(const common::ObString &uri,
     CLOG_LOG(WARN, "ObLogExternalStorageHandler invalid argument", K(uri), K(storage_info), K(offset), KP(buf), K(read_buf_size));
   } else if (OB_FAIL(handle_adapter_->get_file_size(uri, storage_info, file_size))) {
     CLOG_LOG(WARN, "get_file_size failed", K(uri), K(storage_info), K(offset), KP(buf), K(read_buf_size));
-  } else if (offset >= file_size) {
+  } else if (offset > file_size) {
-    ret = OB_INVALID_ARGUMENT;
+    ret = OB_FILE_LENGTH_INVALID;
     CLOG_LOG(WARN, "read position lager than file size, invalid argument", K(file_size), K(offset), K(uri));
+  } else if (offset == file_size) {
+    real_read_size = 0;
+    CLOG_LOG(TRACE, "read position equal to file size, no need read data", K(file_size), K(offset), K(uri));
   } else if (FALSE_IT(time_guard.click("after get file size"))) {
     // NB: limit read size.
   } else if (FALSE_IT(real_read_buf_size = std::min(file_size - offset, read_buf_size))) {

src/logservice/ob_log_external_storage_handler.h

@@ -92,6 +92,7 @@ public:
   //   OB_BACKUP_PERMISSION_DENIED, permission denied.
   //   OB_BACKUP_FILE_NOT_EXIST, uri not exist.
   //   OB_OSS_ERROR, oss error.
+  //   OB_FILE_LENGTH_INVALID, read offset is greater than file size.
   //   OB_NOT_INIT
   //   OB_NOT_RUNNING
   //

src/logservice/ob_log_external_storage_io_task.cpp

@@ -336,7 +336,7 @@ int ObLogExternalStorageIOTaskHandleAdapter::pread(const ObString &uri,
                                                    const int64_t read_buf_size,
                                                    int64_t &real_read_size)
 {
-  ObTimeGuard time_guard("oss pread", 100 * 1000);
+  ObTimeGuard time_guard("storage pread", 100 * 1000);
   int ret = OB_SUCCESS;
   real_read_size = 0;
   ObIODevice *io_device = NULL;

unittest/logservice/test_log_external_storage_handler.cpp

@@ -61,8 +61,15 @@ public:
   {
     // 假设8M每秒的读取速度
     const int64_t sleep_us = read_buf_size / (8);
+    int ret = OB_SUCCESS;
     usleep(sleep_us);
-    real_read_size = read_buf_size;
+    if (offset == palf::PALF_PHY_BLOCK_SIZE) {
+      real_read_size = 0;
+    } else if (offset > palf::PALF_PHY_BLOCK_SIZE) {
+      ret = OB_FILE_LENGTH_INVALID;
+    } else {
+      real_read_size = read_buf_size;
+    }
     // while (true) {
     //   int64_t old_real_read_size = ATOMIC_LOAD(&real_read_size);
     //   int64_t new_real_read_size = old_real_read_size + read_buf_size;
@@ -165,8 +172,10 @@ TEST(TestLogExternalStorageHandler, test_log_external_storage_handler)
     EXPECT_EQ(OB_SUCCESS, handler.pread(uri, empty_storage_info, offset, read_buf, read_buf_size, real_read_size));
     int64_t invalid_offset = -1;
     EXPECT_EQ(OB_INVALID_ARGUMENT, handler.pread(uri, storage_info, invalid_offset, read_buf, read_buf_size, real_read_size));
-    invalid_offset = 100*1024*1024;
+    // 读偏移等于文件长度，返回成功，real_read_size=0
-    EXPECT_EQ(OB_INVALID_ARGUMENT, handler.pread(uri, storage_info, invalid_offset, read_buf, read_buf_size, real_read_size));
+    int64_t valid_offset = 64*1024*1024;
+    EXPECT_NE(OB_INVALID_ARGUMENT, handler.pread(uri, storage_info, valid_offset, read_buf, read_buf_size, real_read_size));
+    EXPECT_EQ(0, real_read_size);
     char *invalid_read_buf = NULL;
     EXPECT_EQ(OB_INVALID_ARGUMENT, handler.pread(uri, storage_info, offset, invalid_read_buf, read_buf_size, real_read_size));
     int64_t invalid_read_buf_size = 0;
@@ -215,6 +224,9 @@ TEST(TestLogExternalStorageHandler, test_log_external_storage_handler)
   // 验证公有函数
   {
     real_read_size = 0;
+    int64_t invalid_offset = 100*1024*1024;
+    EXPECT_EQ(OB_FILE_LENGTH_INVALID, handler.pread(uri, storage_info, invalid_offset, read_buf, read_buf_size, real_read_size));
+
     EXPECT_EQ(OB_SUCCESS, handler.pread(uri, storage_info, offset, read_buf, read_buf_size, real_read_size));
     EXPECT_EQ(read_buf_size, real_read_size);
     CLOG_LOG(INFO, "after first read", K(read_buf_size), K(real_read_size));