Entries are at the heart of all logging performed by Stumpless. While they may
not be explicitly created by calls such as the
stumpless function, they are
still involved behind the scenes. Understanding how to use them will lead to
cleaner and more performant code.
Entries are modeled directly after the hierarchy defined in RFC 5424, including most fields of the message as well as the structured data. When creating a new entry the mandatory fields are supplied, and then any structured data is added to the entry afterwards.
entry = stumpless_new_entry( STUMPLESS_FACILITY_USER, STUMPLESS_SEVERITY_INFO, "my-app-name", "my-msgid", "my event message" );
Fields such as the timestamp and the process id will be automatically filled in when the message is actually logged to a target. Note that there is no need to end the message with a newline, as delimitting is taken care of by the library itself.
The message can take any format specifiers that are valid in printf, so messages can be crafted to contain extra information, like this:
entry = stumpless_new_entry( STUMPLESS_FACILITY_USER, STUMPLESS_SEVERITY_INFO, "my-app-name", "my-msgid", "message by user %s", username );
If you need to update the message with a different user later, you’ll need to reset the message of the entry like this:
stumpless_set_entry_message( entry, "message by user %s", username );
While this creates an entry with a message containing specific information, it’s often more useful to put this information into the structured data of the entry so that it can be parsed and indexed efficiently by a remote collector such as Splunk. For the above example of a username, you could add this information to the entry like this:
element = stumpless_new_element( "user" ); param = stumpless_new_param( "username", username ); stumpless_add_param( element, param ); stumpless_add_element( entry, element );
This is certainly much more verbose than using the format string style, but it does result in a more structured message that can be cleanly parsed. In more complex messages with many pieces of information that should be included, this method may become easier to manage.