The logging module provides the following classes:
|Log-api| is the core class of the logging module. This singleton is not only in charge of the logging operations (see :ref:`dds_layer_log_logging`), but it also provides configuration APIs to set different logging configuration aspects (see :ref:`dds_layer_log_config`), as well as logging filtering at various levels (see :ref:`dds_layer_log_filter`). It contains zero or more |LogConsumer-api| objects. The singleton's consuming thread feeds the log entries added to the logging queue using the macros defined in :ref:`dds_layer_log_logging` to the log consumers sequentially (see :ref:`dds_layer_log_thread`).
Warning
|Log-api| API exposes member function |Log::QueueLog-api|. However, this function is not intended to be used directly. To add messages to the log queue, use the methods described in :ref:`dds_layer_log_logging`.
|LogConsumer-api| is the base class for all the log consumers (see :ref:`dds_layer_log_consumer`). It includes the member functions that derived classes should overload to consume log entries.
|OstreamConsumer-api| derives from |LogConsumer-api|. It defines how to consume log entries for outputting to an |std::ostream-api| object. It includes a member function that derived classes must overload to define the desired |std::ostream-api| object.
1. |StdoutConsumer-api| derives from |OStreamConsumer-api|. It defines STDOUT as the output |std::ostream-api| object (see :ref:`dds_layer_ostream_consumer_stdout`).
2. |StdoutErrConsumer-api| derives from |OStreamConsumer-api|. It defines a |Log::Kind-api| threshold so that if the |Log::Kind-api| is equal to or more severe than the selected threshold, the output defined will be STDERR. Otherwise, it defines STDOUT as the output (see :ref:`dds_layer_ostream_consumer_stdouterr`).
3. |FileConsumer-api| derives from |OStreamConsumer-api|. It defines an user specified file as the output |std::ostream-api| object (see :ref:`dds_layer_ostream_consumer_file`).
Logging module class diagram
The module can be further extended by creating new consumer classes deriving from |LogConsumer-api| and/or |OStreamConsumer-api|. To enable a custom consumer just follow the instructions on :ref:`dds_layer_log_register_consumers`.