DLT：dlt-daemon示例解析2-编程知识

DLT：dlt-daemon示例解析

回顾一下上期第一个示例打印DLT日志的流程。

这次来分析第二个示例。

目录dlt-daemon/examples/example2/下有以下文件

CMakeLists.txt dlt_id.h example2.c example2.xml

其中example2.xml编译用不到，里面描述了一些程序的信息，我们先不管它。

// CMakeLists.txt

#######
# SPDX license identifier: MPL-2.0
#
# Copyright (C) 2011-2015, BMW AG
#
# This file is part of GENIVI Project DLT - Diagnostic Log and Trace.
#
# This Source Code Form is subject to the terms of the
# Mozilla Public License (MPL), v. 2.0.
# If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.
#
# For further information see http://www.genivi.org/.
########
# DLT example implementation
#cmake_minimum_required( VERSION 2.6 )
project( automotive-dlt-example2 )#
# find dependency packages
#find_package(PkgConfig)
pkg_check_modules(DLT REQUIRED automotive-dlt)#
# include directories
#include_directories(${DLT_INCLUDE_DIRS}
)#
# build project
#set(dlt_example2_SRCS example2.c)
add_executable(dlt-example2 ${dlt_example2_SRCS})
target_link_libraries(dlt-example2 ${DLT_LIBRARIES})
set_target_properties(dlt-example2 PROPERTIES LINKER_LANGUAGE C)install(TARGETS dlt-example2RUNTIME DESTINATION binCOMPONENT base)

//dlt_id.h

/** SPDX license identifier: MPL-2.0** Copyright (C) 2011-2015, BMW AG** This file is part of GENIVI Project DLT - Diagnostic Log and Trace.** This Source Code Form is subject to the terms of the* Mozilla Public License (MPL), v. 2.0.* If a copy of the MPL was not distributed with this file,* You can obtain one at http://mozilla.org/MPL/2.0/.** For further information see http://www.genivi.org/.*//* generated file, do not edit */#ifndef DLT_ID_H
#define DLT_ID_H#define DLT_EXA2_CON_EXA2_ID1 1000
#define DLT_EXA2_CON_EXA2_ID2 1001
#define DLT_EXA2_CON_EXA2_ID3 1002#endif /* DLT_ID_H */

文件中用宏定义了3个ID，打印log时使用，没有什么特殊意义。

//example2.c


/** SPDX license identifier: MPL-2.0** Copyright (C) 2011-2015, BMW AG** This file is part of GENIVI Project DLT - Diagnostic Log and Trace.** This Source Code Form is subject to the terms of the* Mozilla Public License (MPL), v. 2.0.* If a copy of the MPL was not distributed with this file,* You can obtain one at http://mozilla.org/MPL/2.0/.** For further information see http://www.genivi.org/.*//*!* \author Alexander Wenzel <alexander.aw.wenzel@bmw.de>** \copyright Copyright © 2011-2015 BMW AG. \n* License MPL-2.0: Mozilla Public License version 2.0 http://mozilla.org/MPL/2.0/.** \file example2.c*//*******************************************************************************
**                                                                            **
**  SRC-MODULE: example2.c                                                    **
**                                                                            **
**  TARGET    : linux                                                         **
**                                                                            **
**  PROJECT   : DLT                                                           **
**                                                                            **
**  AUTHOR    : Alexander Wenzel Alexander.AW.Wenzel@bmw.de                   **
**                                                                            **
**  PURPOSE   :                                                               **
**                                                                            **
**  REMARKS   :                                                               **
**                                                                            **
**  PLATFORM DEPENDANT [yes/no]: yes                                          **
**                                                                            **
**  TO BE CHANGED BY USER [yes/no]: no                                        **
**                                                                            **
*******************************************************************************/#include <stdio.h>      /* for printf() and fprintf() */
#include <stdlib.h>     /* for atoi() and exit() */#include <dlt.h>#include "dlt_id.h"DLT_DECLARE_CONTEXT(con_exa2);int main()
{int num;struct timespec ts;DLT_REGISTER_APP("EXA2", "Third Example");DLT_REGISTER_CONTEXT(con_exa2, "CON", "First context");DLT_NONVERBOSE_MODE();for (num = 0; num < 10; num++) {DLT_LOG_ID(con_exa2, DLT_LOG_INFO, DLT_EXA2_CON_EXA2_ID1, DLT_INT32(12345678), DLT_STRING("Hello world 1!"));DLT_LOG_ID(con_exa2, DLT_LOG_ERROR, DLT_EXA2_CON_EXA2_ID2, DLT_INT32(87654321), DLT_STRING("Hello world 2!"));DLT_LOG_ID(con_exa2, DLT_LOG_WARN, DLT_EXA2_CON_EXA2_ID3, DLT_INT32(11223344), DLT_STRING("Hello world 3!"));ts.tv_sec = 0;ts.tv_nsec = 1000000;nanosleep(&ts, NULL);}DLT_UNREGISTER_CONTEXT(con_exa2);DLT_UNREGISTER_APP();
}

Application ID是“EXA2”, Context ID是“CON”。

这里的流程与示例1相比有变化：

1. 增加了DLT_NONVERBOSE_MODE设置。

2. 打印log的位置换成了 DLT_LOG_ID.

3. 打印的内容变成多条，更贴近实际。

4. 每条消息中的等级不同，包括INFO，ERROR，WARN等。消息中增加了ID，消息包括int和String多种类型。

三条消息每条打印10次。

DLT_NONVERBOSE_MODE

/*** Switch to non-verbose mode**/
#define DLT_NONVERBOSE_MODE() do { \(void)dlt_nonverbose_mode(); } while(false)

这个宏调用了dlt_nonverbose_mode()函数，含义为切换到非冗余模式。默认是冗余模式。

简单说明下非冗余模式和冗余模式：

NonVerbose Mode

To be able to transmit parameter values only - without the need of any meta information about them -, additional properties like parameter names or types -, the Non-Verbose Mode can be used.

To allow the correct disassembly of the contained parameter values within a received Dlt message, a dedicated Message ID is added to the payload.

A separate, external file contains the description of the payload layout according to the corresponding Message ID.

概况的说就是传递消息比较简洁。

数据格式如下，消息头后面就是消息ID和数据

Verbose Mode

Dlt messages which are sent in Verbose Mode contain a complete description of the parameters next to the parameter values itself.

This means that on the one hand no external file is needed for disassembly; On the other hand, a higher amount of data is sent on the bus.

The Verbose Mode can be used on ECUs where enough memory and high network bandwidth are available. Because of the self-description, the stored data on the external client is interpretable at any time and without any further external information.

通俗的含义就是什么详细信息都发，发的数据多所以用在内存充足而且网络带宽高的地方。

数据格式比上面详细很多。

DLT_LOG_ID

/*** Send log message with variable list of messages (intended for non-verbose mode)* @param CONTEXT object containing information about one special logging context* @param LOGLEVEL the log level of the log message* @param MSGID the message id of log message* @param ... variable list of arguments* calls to DLT_STRING(), DLT_BOOL(), DLT_FLOAT32(), DLT_FLOAT64(),* DLT_INT(), DLT_UINT(), DLT_RAW()* @note To avoid the MISRA warning "The comma operator has been used outside a for statement"*       use a semicolon instead of a comma to separate the __VA_ARGS__.*       Example: DLT_LOG_ID(hContext, DLT_LOG_INFO, 0x1234, DLT_STRING("Hello world"); DLT_INT(123));*/
#ifdef _MSC_VER
/* DLT_LOG_ID is not supported by MS Visual C++ */
/* use function interface instead               */
#else
#   define DLT_LOG_ID(CONTEXT, LOGLEVEL, MSGID, ...) \do { \DltContextData log_local; \int dlt_local; \dlt_local = dlt_user_log_write_start_id(&CONTEXT, &log_local, LOGLEVEL, MSGID); \if (dlt_local == DLT_RETURN_TRUE) \{ \__VA_ARGS__; \(void)dlt_user_log_write_finish(&log_local); \} \} while(false)
#endif

发送带有消息变量列表的日志消息（用于NonVerbose Mode）。日志带ID。

带有ID的日志更有实用性，可以区分不同来源的日志。运行的结果在dlt-viewer中显示如下：