The UHD logging facility

Application Note Information

AN-001 by Michael Dickens

Overview

This application note describes the UHD logging facility: compile-time options, runtime options, application usage, default values and how all of these interact.

Code

UHD has 3 primary files associated with logging: log.hpp, log.cpp, and UHDLog.cmake. There are secondary logging files providing an interface to C and Python.

Concepts

There are 7 logging levels; the name and number can be used interchangeably for any logging variable.

UHD Logging Levels

trace	0
debug	1
info	2
warning	3
error	4
fatal	5
off	6

There are 2 distinct times where logging can be controlled: during compilation per CMake settings, and during runtime via shell environment variables.

CMake Logging Settings

There are 4 CMake variables that control logging: UHD_LOG_MIN_LEVEL, UHD_LOG_CONSOLE_DISABLE, UHD_LOG_FILE_LEVEL, and UHD_LOG_CONSOLE_LEVEL. Each of these variables can be set independently via the CMake commandline or other methods, and override each's default value. The default values for these variables depend on whether the CMAKE_BUILD_TYPE is debug or not, as follows:

UHD CMake Logging Variables and Default Values for different CMAKE_BUILD_TYPE

Variable	non-Debug	Debug
UHD_LOG_MIN_LEVEL	debug (1)
UHD_LOG_CONSOLE_DISABLE	OFF
UHD_LOG_FILE_LEVEL	info (2)	trace (0)
UHD_LOG_CONSOLE_LEVEL	info (2)	debug (0)