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Wiki page log-levels.md changed with summary [] by Gareth Halfacree

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Gareth Halfacree 2017-12-05 07:32:53 -08:00 committed by apache
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pages/develop/debug/log-levels.md.txt
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@ -69,4 +69,22 @@ While developing your libraries or applications, you may notice that ``EINA_LOG_
EINA_LOG_LEVEL={N} EINA_LOG_LEVELS_GLOB=eina_*:0 ./{application}
```
Removing these internal logs from the output makes it easier for you to see your own domain messages.
Removing these internal logs from the output makes it easier for you to see your own domain messages.
## Eina_Log_Group Log ##
``Eina`` provides ``eina_log_print()``, a standard function to manage all logging messages. This function may be called directly or using helper macros including ``EINA_LOG_DBG()``, ``EINA_LOG_ERR()`` or those that take a specific domain as an argument as with ``EINA_LOG_DOM_DBG()`` and ``EINA_LOG_DOM_ERR()``. Internally, ``eina_log_print()`` will call the function defined with ``eina_log_print_cb_set()``, which defaults to ``eina_log_print_cb_stderr()`` but may be changed to do whatever you need such as networking or syslog logging.
The logging system is thread-safe once initialized with ``eina_log_threads_enable()``. The thread that calls this function first is considered "main thread" and other threads will have their thread id (``pthread_self()``) printed in the log message so it is easy to detect from where the messages are coming.
The different logging levels serve to customize the amount of debugging information and may be used to automatically call ``abort()`` once a message of a given level is printed. This is controlled by the environment variable ``EINA_LOG_ABORT`` and the level to be considered critical with ``EINA_LOG_ABORT_LEVEL``. These can be changed with ``eina_log_abort_on_critical_set()`` and ``eina_log_abort_on_critical_level_set()``.
The default maximum level to print is defined by the environment variable ``EINA_LOG_LEVEL`` but may be set per-domain with ``EINA_LOG_LEVELS``. It will default to ``EINA_LOG_ERR``. This can be changed with ``eina_log_level_set()``.
To use the log system ``Eina`` must be initialized with ``eina_init()`` and later shut down with ``eina_shutdown()``.
## Controlling Print Callbacks ##
The log module allows the user to change the way ``eina_log_print()`` displays messages. It suffices to pass to ``eina_log_print_cb_set()`` the function used to display the message. That function must be of type ``#Eina_Log_Print_Cb``. As custom data can be passed to that callback, customised messages can be displayed.
It is suggested to not use ``__FILE__``, ``__FUNCTION__`` or ``__LINE__`` when writing that callback, but when defining macros like ``EINA_LOG_ERR()`` and others.