import { MetricMap, Gauge, Histogram } from '@spinajs/telemetry-common';
/**
 * Point-in-time view of a driver's connection pool.
 */
export interface IPoolMetrics {
    /** Connections currently open ( idle + in use ). */
    Size: number;
    /** Connections currently checked out by a query. */
    InUse: number;
    /** Callers waiting for a free connection. */
    Waiting: number;
}
/**
 * Prefix `Metrics.defineMetrics` puts in front of every name below.
 */
export declare const ORM_METRIC_PREFIX = "orm";
/** Key of a metric inside the {@link MetricMap} — the name WITHOUT the `orm_` prefix. */
export declare const ORM_METRIC_KEY_POOL_SIZE = "pool_size";
export declare const ORM_METRIC_KEY_POOL_IN_USE = "pool_in_use";
export declare const ORM_METRIC_KEY_POOL_WAITING = "pool_waiting";
export declare const ORM_METRIC_KEY_ACQUIRE_SECONDS = "pool_acquire_seconds";
export declare const ORM_METRIC_KEY_CONNECTION_STATE = "connection_state";
/** Fully qualified metric names, as they appear in the Prometheus exposition text. */
export declare const ORM_METRIC_POOL_SIZE = "orm_pool_size";
export declare const ORM_METRIC_POOL_IN_USE = "orm_pool_in_use";
export declare const ORM_METRIC_POOL_WAITING = "orm_pool_waiting";
export declare const ORM_METRIC_ACQUIRE_SECONDS = "orm_pool_acquire_seconds";
export declare const ORM_METRIC_CONNECTION_STATE = "orm_connection_state";
/**
 * Acquiring a pooled connection is normally sub-millisecond and only becomes interesting once the
 * pool saturates, so the buckets are dense at the bottom and reach far enough to show a caller
 * that queued for seconds. prom-client's linear default ( 1..10 SECONDS ) would put every healthy
 * acquire in the first bucket and tell us nothing.
 */
export declare const ORM_ACQUIRE_BUCKETS_SECONDS: number[];
/**
 * The ORM's metric set, built against the shared `Metrics` service from
 * `@spinajs/telemetry-common`.
 *
 * The ORM deliberately depends on `-common` and NOT on `@spinajs/telemetry`: that package pulls in
 * `@spinajs/http`, `@spinajs/log`, `@spinajs/validation` and `@spinajs/configuration`, and putting
 * the HTTP stack underneath every database connection inverts the dependency graph. `-common`
 * needs nothing but `@spinajs/di` and prom-client. `@spinajs/telemetry` re-exports it, so the
 * `/metrics` endpoint renders the very registry these metrics land in — no wiring needed.
 *
 * Returns null rather than throwing when the service cannot be resolved: publishing a metric must
 * never be able to fail a query or a health probe.
 */
export declare function ormMetrics(): MetricMap | null;
/** Narrowing helpers: `defineMetrics` is typed by its declarations, not by the values it returns. */
export declare function ormGauge(map: MetricMap, key: string): Gauge<string>;
export declare function ormHistogram(map: MetricMap, key: string): Histogram<string>;
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