Logging (C API)

emlearn has support for structured logging. This is primarily used internally, but may be used by applications.

A structured log entry consist of an event identifier, along with key/value pairs. An entry is serialized with logfmt:

event-name key1=value1 key2=value2\n

Structured logging has the following advantages:

Machine-readable. Easy to analyze with scripts
Event names should be unique and stable. Easy to search for
Indexable, including on particular keys/values. Can be merged with other data sources

Typical usage:

EML_LOG_BEGIN("my-event");
EML_LOG_ADD("key1", "string-value");
EML_LOG_ADD_INTEGER("key2", 123);
EML_LOG_ADD_BOOL("key3", true);
EML_LOG_ADD_FLOAT("key2", 3.14);
EML_LOG_END();

Defines

EML_LOG_ENABLE

Enable logging.

To enable #define EML_LOG_ENABLE 1 Default is OFF.

EML_LOG_PRINTF(...)

EML_LOG_PRINT_ARRAY(arr, len, fmt)

EML_LOG_BOOL_STR(b)

EML_LOG_BEGIN(eventname): Start a log entry

EML_LOG_END(): End a log entry

EML_LOG_ADD(key, str): Add a key/value pair (strings)

EML_LOG_ADD_INTEGER(key, integer): Add an integer value

EML_LOG_ADD_BOOL(key, boolean): Add a boolean value

EML_LOG_ADD_FLOAT(key, flt): Add a floating-point value

EML_LOG_ADD_ARRAY(key, arr, len, fmt): Add an array