import { MomentoLoggerFactory } from '../../';
import { ExperimentalMetricsMiddleware } from './impl/experimental-metrics-middleware';
/**
 * This middleware enables per-request client-side metrics.  Metrics for each
 * request will be written to logs; the log data can be analyzed or shared
 * with Momento to diagnose performance issues.
 *
 * The metrics format is currently considered experimental; in a future release,
 * once the format is considered stable, this class will be renamed to remove
 * the Experimental prefix.
 *
 * It also enables regular logging of congestion in the node event loop. Once
 * per second it will output the event loop utilization ratio, as well as stats
 * about the event loop delay, measured in 20ms increments.
 *
 * WARNING: enabling this middleware may have minor performance implications,
 * so enable with caution.
 *
 * WARNING: depending on your request volume, this middleware will produce a high
 * volume of log output. If you are writing logs directly to local disk, be aware
 * of disk usage and make sure you have log rotation / compression enabled via a
 * tool such as `logrotate`.
 *
 * See `advanced.ts` in the examples directory for an example of how to set up
 * your {Configuration} to enable this middleware.
 */
export declare class ExperimentalMetricsLoggingMiddleware extends ExperimentalMetricsMiddleware {
    constructor(loggerFactory: MomentoLoggerFactory);
}