/**
 * Lifecycle state of a driver's connection to its database.
 */
export declare enum ConnectionState {
    Disconnected = "disconnected",
    Connecting = "connecting",
    Connected = "connected",
    /** Reachable but failing health probes, or mid-reconnect. Queries are still attempted. */
    Degraded = "degraded"
}
export interface IConnectionResilienceOptions {
    /**
     * Milliseconds between health probes. 0 disables the periodic probe. Default 30000.
     */
    HealthCheckInterval?: number;
    /**
     * Reconnect attempts per outage before giving up. Default 5.
     */
    MaxRetries?: number;
    /**
     * First backoff delay in ms; doubles each attempt. Default 200.
     */
    RetryDelay?: number;
    /**
     * Upper bound on the backoff delay in ms. Default 5000.
     */
    MaxRetryDelay?: number;
}
/**
 * Error codes that mean the transport died rather than the statement being wrong. Retrying a
 * statement that the server rejected only multiplies the failure, so this set is deliberately
 * narrow: connection-level Node socket errors plus the mysql2 protocol codes for a lost or
 * exhausted connection.
 */
export declare const RETRYABLE_ERROR_CODES: ReadonlySet<string>;
/**
 * Backoff delay for attempt `n` (0-based), doubling from `base` and clamped to `max`.
 */
export declare function backoffDelay(attempt: number, base: number, max: number): number;
/**
 * Promise-returning sleep used by the retry loop.
 */
export declare function delay(ms: number): Promise<void>;
/**
 * Walks an error and its `inner` / `cause` chain looking for a retryable code. Driver errors are
 * frequently wrapped ( OrmException carries the original in `inner` ), so a shallow check misses
 * exactly the cases that matter.
 */
export declare function isRetryableErrorCode(err: unknown): boolean;
//# sourceMappingURL=resilience.d.ts.map