Logging & Reports

Days writes periodic CSV reports through CsvLogger (src/utils/logger.rs).

How reporting works

• Components construct report structs (e.g., PacketSourceReport, SchedulerReport).
• Reports are appended to an in-memory buffer (guarded by a lock).
• When buffers grow beyond a threshold, the logger flushes a batch to disk.
• At the end of the run, CsvLogger::flush_reports() flushes all remaining data.

The logger is initialized once from config at the start of Topology::run.

Output files

All files are written under log_path (default: ./output/):

• sources.csv: source reports (PacketSourceReport)
• sinks.csv: sink reports (PacketSinkReport)
• switches.csv: scheduler reports (SchedulerReport)
• pfc.csv: PFC ingress port reports (PfcPortReport, only with l2_pfc)
• dcqcn_events.csv: per-event DCQCN trace rows (only with dcqcn + lean)
• pfc_events.csv: per-event PFC trace rows (only with l2_pfc + lean)
• cubic_events.csv: per-event TCP CUBIC trace rows (only with lean)
• drr_events.csv: per-event DRR trace rows (only with lean)
• wfq_events.csv: per-event WFQ trace rows (only with lean)

Report interval

Set report_interval in the TOML config:

• if omitted, it defaults to f64::MAX (effectively “only final flush”),
• if set, many models schedule periodic events to emit reports.

See /docs/configuration/logging for configuration details.