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An Interface for Message Logging

Overview

This package provides an interface to log text messages. If the library is used on an installed ROS system, the backend uses the ROS logging mechanism. Otherwise the messages are forwarded to std::cout.

The source code is released under a BSD 3-Clause license.

Author(s): Christian Gehring Date: Dec. 2014

Building

In order to install, clone the latest version from this repository into your catkin workspace and compile the packages.

Usage

Selecting the Backend

This library defines macros to wrap to ROS logger macros or to std::cout calls. The default backend is the ROS logger. You can enable the usage of std::cout by defining MELO_USE_COUT in the CMakeLists.txt of your package:

add_definitions(-DMELO_USE_COUT)

Enabling Sentry

Sentry is a tool for automatic error reporting. Please note that building message logger with Sentry requires the closed-source packages sentry_native and anymal_sentry_native to be available. By default, message logger is built with Sentry in case these dependencies are found. You can overwrite this behavior by defining MELO_USE_SENTRY in the CMakeLists.txt of your package:

add_definitions(-DMELO_USE_SENTRY=OFF)

On top of building message logger with Sentry, you also need to "soft-enable" Sentry with the following ROS parameters

  • The feature toggle /config/feature_toggles/error_reporting globally sets the global level of error reporting. Set it to automatic_minimal or automatic_full to enable Sentry.
  • If needed, Sentry can be disabled for specific nodes by setting the "local" parameter automatic_error_reporting to false.

Note that while it is possible to compile message logger with Sentry but without ROS, Sentry won't be able to read metadata from the ROS parameter server in this case.

Also note that when Sentry creates an error, it allocates memory on the head using malloc. In safety-critical applications this can lead to issues, therefore it is recommended to disable Sentry in these cases.

Logging Levels

Five logging levels are defined: debug, info, warning, error, fatal.

The following logging levels are compiled per default:

std::cout built in Debug: debug, info, warning, error, fatal.

std::cout built in Release: info, warning, error, fatal.

ROS built in Debug or Release: debug, info, warning, error, fatal.

Note that when using the ROS backend, even though the debug level is kept when compiling, it does not show up in the console. This can be changed by calling the set_logger_level service of your node change the logger level online.

To change which logger levels are kept when compiling, set the MELO_MIN_SEVERITY to your desired level in the CMakeLists.txt of your package, e.g.:

add_definitions(-DMELO_MIN_SEVERITY=MELO_SEVERITY_INFO)

The available levels are

  • MELO_SEVERITY_DEBUG: Keep all logs.
  • MELO_SEVERITY_INFO: Remove debug logs.
  • MELO_SEVERITY_WARN: Remove debug and info logs.
  • MELO_SEVERITY_ERROR: Keep only error and fatal logs.
  • MELO_SEVERITY_FATAL: Keep only fatal logs.
  • MELO_SEVERITY_NONE: Remove all logs.

The fatal logging variants throw an exception and therefore terminate the program, if the exception is not captured.

Additional Output

This library can also prepend the class and function name of the log function callers, e.g. void MyClass::MyFunction() { MELO_INFO("bla bla"); } prints [Info] [Timestamp] [MyClass::MyFunction] bla bla. You can enable this feature by defining MELO_FUNCTION_PRINTS in the CMakeLists.txt of your package:

add_definitions(-DMELO_FUNCTION_PRINTS)

Note that when using the ROS backend, it is better to use its built in functionality to print more information.