Module logging 

File-based log writing for hermod-tracer

Each node gets its own subdirectory under the configured logRoot. Within that directory, log output is written to a timestamped file:

{logRoot}/
└── {node-id}/
    ├── node-2024-01-15T10-30-00.json   ← previous file
    ├── node-2024-01-15T12-00-00.json   ← current file
    └── node.json                        ← symlink → current file

The symlink is updated atomically via a .tmp rename so readers always see a consistent target.

Two formats are supported:

• LogFormat::ForHuman — "{timestamp} [{severity}] {namespace} {message}\n"
• LogFormat::ForMachine — one JSON object per line (newline-delimited JSON)

Structs

LogHandle

One open log file

LogKey

A key into the handle cache

LogWriter

Shared writer — holds open file handles for all active (node, logging-config) pairs

Functions

format_human

Human-readable format: {timestamp} [{severity}] {namespace} {message}\n

format_machine

Machine-readable format: JSON line

format_trace

Format a single trace as a line (with trailing newline)