Module metrics 

Prometheus metrics for the column pager.

One process-wide PagerMetrics singleton, installed by compute init via register. Counter observers (observe_*) are no-ops until that call lands; the lazy initialization keeps tests and benches that don’t wire a MetricsRegistry free of bookkeeping.

Structs

PagerMetrics

Process-wide pager metrics. Counters track cumulative observations since process start; gauges read the live policy atomics at scrape time.

Functions

register

Install the pager metrics into registry. Idempotent — repeated calls after the first one are no-ops. Computed gauges read the singleton TieredPolicy atomics at scrape time; their values reflect the live policy whether or not the column-paged batcher is currently enabled.