SQLite Observer & Exporter for SQLite

This provides a fairly simple SQLite powered backend for the metrics crate, useful for offline or desktop applications to gather metrics that can be easily queried afterwards.

Example

    let exporter = SqliteExporter::new(
        Duration::from_secs(30), // flush to sqlite on disk every 30s (or internal buffer limit)
        Some(Duration::from_secs(60 * 60 * 24 * 7)), // 60 sec * 60 min * 24 hours * 7 days
        "metrics.db",
    )
    .expect("Failed to create SqliteExporter");
    exporter
        .install()
        .expect("Failed to install SqliteExporter");

// use metrics macros etc.
metrics::gauge!("mykey", 1.0);