Logging

Generate and print log messages.

This library allows other libraries to generate and print log messages, which can aid in debugging. Log messages are printed by passing strings to one of the logging functions. The features of this library include:

• Configurable levels for log messages and libraries.
• Automatic printing of log level, library name, and time with every message. The information printed with each message may be customized.
• A function to print the contents of buffers when using the debug log level. This allows the contents of memory to be easily examined.

Dependencies

Dependencies of the logging library.

Logging direct dependencies

Currently, the logging library has the following dependencies:

• The platform clock component for generating the timestring to print in log messages.
• When IOT_STATIC_MEMORY_ONLY is 1, the logging library depends on the platform static memory component to allocate buffers for log messages. When IOT_STATIC_MEMORY_ONLY is 0, the logging library will default to using the standard library's malloc and free functions. The logging library's memory allocation functions may always be overridden. Note that the logging library will silently discard logs if it fails to allocate memory for the message.

Setup and use

How to set up and use the logging library.

The file iot_logging_setup.h should be included to configure logging for a single source file. Before including iot_logging_setup.h, the constants LIBRARY_LOG_LEVEL and LIBRARY_LOG_NAME must be defined.

For example, to configure all the "SAMPLE" library to print all messages below the info log level:

// Print log messages up to the "info" level.
#define LIBRARY_LOG_LEVEL    IOT_LOG_INFO

// Print library name "SAMPLE".
#define LIBRARY_LOG_NAME     "SAMPLE"

// Including this header defines the logging macros using LIBRARY_LOG_LEVEL and
// LIBRARY_LOG_NAME.
#include "iot_logging_setup.h"

int main( void )
{
    // After including iot_logging_setup.h, the logging functions can be used.
    IotLogError( "Error." );      // Will be printed because IOT_LOG_ERROR <= LIBRARY_LOG_LEVEL
    IotLogWarn( "Warning. " );    // Will be printed because IOT_LOG_WARN <= LIBRARY_LOG_LEVEL
    IotLogInfo( "Info." );        // Will be printed because IOT_LOG_INFO <= LIBRARY_LOG_LEVEL
    IotLogDebug( "Debug." );      // Will not be printed because IOT_LOG_DEBUG > LIBRARY_LOG_LEVEL

    return 0;
}

The code above will print something like the following:

[ERROR][SAMPLE][2018-01-01 12:00:00] Error.
[WARN ][SAMPLE][2018-01-01 12:00:00] Warning.
[INFO ][SAMPLE][2018-01-01 12:00:00] Info.