Basic Support for Logging

[nobugs-hare]

API:

• Somehwhat reminiscent of Node.js' Winston, but using levels from syslogd: emerg, alert, crit, err, warning, notice, info, debug
• formatting based on {fmt}
• adding a new dimension to the logging - 'module' . Module is an optional StringLiteral first (!) parameter to a log() call; if not specified (which is majority of cases) it defaults to a well-known #define (which can be redefined by end-user). In general, module corresponds to Node, though some libraries MAY specify their own modules.
• ideally, logger SHOULD be a member of user-defined Node (and NOT of generic Node) - (a) to facilitate multiple loggers etc., and (b) to be more consistent with Node.js practices.

Implementation:

• usually completely non-blocking (starting to skip when not able to cope) - unless specified otherwise for a level
• for the time being - supporting only file as a target
• for the time being - no support for filtering.

[divanchykhin]

Corrections:
a. Base Node class has a (default) Log which could be used, in particular, by other libraries/modules within the context of the same Node (such usage is implemented via a pointer stored in TLS)
b. Node-based classes may have their own Logs.

[divanchykhin]

Correction:
a. Levels to use: fatal, err, warning, info, debug
b. Further internal remapping for particular targets (such as syslogd) is possible