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|
DLT Cheatsheet
==============
Alexander Wenzel <Alexander.AW.Wenzel@bmw.de>
0.0.1, 2012/10/11: Initial version
image::images/genivi_chrome_1_transparent.png[width=128]
Overview
--------
DLT is quiet easy to use. As an application developer you only need to follow some steps as described in this document.
Initialisation:
- Link your application against the DLT library
- Include the DLT header file
- Register your application
- Define all contexts
- Register all contexts
Now you are ready to write your logs.
Termination:
- Unregister all contexts
- Unregister application
Link your application to DLT library
------------------------------------
If you compile your application with cmake, you have to add the following lines to your CMakeLists.txt.
----
pkg_check_modules(DLT REQUIRED automotive-dlt)
${DLT_INCLUDE_DIRS}
${DLT_LIBRARIES}
----
Include the DLT Header
----------------------
To use DLT you have to include the DLT header file in each file you want to use DLT.
----
#include <dlt/dlt.h>
----
Register your application
-------------------------
You have to register your application as early as possible during the initialisation of your application.
You have to call the DLT_REGISTER_APP().
It is only allowed to call DLT_REGISTER_APP() *once* in your application.
You have to provide a application id, which size is maximum four charcters long. In this example we use "MAPP".
And you can provide also a description for your application, here it is "Test Application for Logging".
----
int main(int argc, const char\* argv\[\])
{
DLT_REGISTER_APP("MAPP","Test Application for Logging");
}
----
If your application uses fork(), you may not call DLT_REGISTER_APP() before fork(). And fork() should never be called after DLT_REGISTER_APP. This is because the DLT library must be initialised for each process, which is done by DLT_REGISTER_APP().
If you are not sure where you are calling DLT_REGISTER_APP() the first time, you can initialise the DLT user library by calling the initialisation routine directly.
----
dlt_user_init();
----
Define all contexts
--------------------
You can create as many contexts as you like.
You can declare one or more contexts in a C or CPP file.
Each context is only allowed to be declared once.
You have to provide a unique variable name for your context.
----
#include <dlt/dlt.h>
DLT_DECLARE_CONTEXT(myContext1);
DLT_DECLARE_CONTEXT(myContext2);
DLT_DECLARE_CONTEXT(myContext3);
----
If you want to use a context in another C or CPP file, you can import the context by calling
----
#include <dlt/dlt.h>
DLT_IMPORT_CONTEXT(myContext1);
DLT_IMPORT_CONTEXT(myContext2);
DLT_IMPORT_CONTEXT(myContext3);
----
Register all contexts
----------------------
After you have registered your application you must register your contexts, early during initialisation of your application.
Do not call DLT_REGISTER_CONTEXT() before DLT_REGISTER_APP().
During registration of each context, you must provide a context id, which size is maximum four charcters long. In this example we use "TESX".
And you can provide also a description for your context, here it is "Test Context X for Logging".
----
int main(int argc, const char\* argv\[\])
{
DLT_REGISTER_APP("MAPP","Test Application for Logging");
DLT_REGISTER_CONTEXT(myContext1,"TES1","Test Context 1 for Logging");
DLT_REGISTER_CONTEXT(mycontext2,"TES2","Test Context 2 for Logging");
DLT_REGISTER_CONTEXT(mycontext3,"TES3","Test Context 3 for Logging");
}
----
Create your logs
----------------
Now you can start creating your logs.
Each log command consist of the context, the log level and a variable number of logging parameters.
Log Level
~~~~~~~~~
The log level must be one of the following values:
[options="header"]
|==================================================================
| Log level | Description
| DLT_LOG_FATAL | fatal system error
| DLT_LOG_ERROR | error with impact to correct functionality
| DLT_LOG_WARN | warning, correct behaviour could not be ensured
| DLT_LOG_INFO | informational (default)
| DLT_LOG_DEBUG | debug
| DLT_LOG_VERBOSE | highest grade of information
|==================================================================
DLT_LOG_FATAL, DLT_LOG_ERROR and DLT_LOG_WARN should be used in your application, when something is going wrong.
DLT_LOG_INFO should be used to send the most important information.
DLT_LOG_DEBUG and DLT_LOG_VERBOSE should be only used for testing information.
Each context is set by default to DLT_LOG_INFO log level. All log message are send, which use this loglevel or a lower loglevel.
If you also want to see DLT_LOG_DEBUG and DLT_LOG_VERBOSE log messages, you have to raise the log level with the DLT viewer.
Logging parameters
~~~~~~~~~~~~~~~~~~
The following parameter types can be used.
You can add one or more parameters to a single log message.
The size of all logging parameters together should not exceed 2kBytes, including the DLT message header.
[options="header"]
|===============================================================
| Type | Description
| DLT_STRING(TEXT) | String
| DLT_RAW(BUF,LENGTH) | Raw buffer
| DLT_INT(VAR) | Integer variable, dependent on platform
| DLT_INT16(VAR) | Integer 16 Bit variable
| DLT_INT32(VAR) | Integer 32 Bit variable
| DLT_INT64(VAR) | Integer 64 bit variable
| DLT_UINT(VAR) | Unsigned integer variable
| DLT_UINT16(VAR) | Unsigned 16 Bit integer variable
| DLT_UINT32(VAR) | Unsigned 32 Bit integer variable
| DLT_UINT64(VAR) | Unsigned 64 bit integer variable
| DLT_BOOL(VAR) | Boolean variable
| DLT_FLOAT32(VAR) | Float 32 Bit variable
| DLT_FLOAT64(VAR) | Float 64 Bitvariable
|===============================================================
Logging command
~~~~~~~~~~~~~~~
Here are some examples for complete log messages.
The contexts must be registered before.
----
DLT_LOG(mycontext1,DLT_LOG_ERROR,DLT_INT(5),DLT_STRING("This is a error"));
DLT_LOG(mycontext2,DLT_LOG_INFO,DLT_INT(5),DLT_STRING("But this only information"));
DLT_LOG(mycontext3,DLT_LOG_DEBUG,DLT_INT(5),DLT_STRING("But this only information"));
----
Unregister contexts and applications
------------------------------------
Before terminating your application you must unregister all registered contexts and unregister at last your application.
----
int main(int argc, const char\* argv\[\])
{
DLT_REGISTER_APP("MAPP","Test Application for Logging");
DLT_REGISTER_CONTEXT(myContext1,"TES1","Test Context 1 for Logging");
DLT_REGISTER_CONTEXT(mycontext2,"TES2","Test Context 2 for Logging");
DLT_REGISTER_CONTEXT(mycontext3,"TES3","Test Context 3 for Logging");
DLT_UNREGISTER_CONTEXT(myContext1);
DLT_UNREGISTER_CONTEXT(mycontext2);
DLT_UNREGISTER_CONTEXT(mycontext3);
DLT_UNREGISTER_APP();
return 0;
}
----
Example
-------
Finally here is a complete example for using DLT:
.dlt_example.c
----
#include <stdio.h>
#include <dlt/dlt.h>
DLT_DECLARE_CONTEXT(myContext1);
DLT_DECLARE_CONTEXT(myContext2);
DLT_DECLARE_CONTEXT(myContext3);
int main()
{
/* register application */
DLT_REGISTER_APP("MAPP","Test Application for Logging");
/* register all contexts */
DLT_REGISTER_CONTEXT(myContext1,"TES1","Test Context 1 for Logging");
DLT_REGISTER_CONTEXT(mycontext2,"TES2","Test Context 2 for Logging");
DLT_REGISTER_CONTEXT(mycontext3,"TES3","Test Context 3 for Logging");
/* Write your logs */
DLT_LOG(mycontext1,DLT_LOG_ERROR,DLT_INT(5),DLT_STRING("This is a error"));
DLT_LOG(mycontext2,DLT_LOG_INFO,DLT_INT(5),DLT_STRING("But this only information"));
DLT_LOG(mycontext3,DLT_LOG_DEBUG,DLT_INT(5),DLT_STRING("But this only information"));
/* Sleep some time */
sleep(3);
/* unregister your contexts */
DLT_UNREGISTER_CONTEXT(myContext1);
DLT_UNREGISTER_CONTEXT(mycontext2);
DLT_UNREGISTER_CONTEXT(mycontext3);
/* unregister your application */
DLT_UNREGISTER_APP();
return 0;
}
----
|
