Function Metrics

Collects execution metrics for the annotated function.

The following metrics are collected: - Execution time. - Success (if function returns a core::result::Result-like type.

The metrics are sent to recorders, which can be thought as backends, which can send for metric aggregation services, for example.

Currently, there are the following recorders implemented: - Log: simply log the metrics. - Prometheus: collect the metrics so they can be sent to Prometheus.