import { Gauge, Counter, Histogram } from 'prom-client';
import { ExtendedGaugeInternal } from 'prometheus-extended-gauge';
import { Pool, Factory } from 'generic-pool';
/**
 * Sensible defaults for the connection pool options
 */
export declare const DEFAULT_CONNECTION_POOL_OPTIONS: PoolConfig<any>;
/**
 * Base interface for the configuration information needed to create a new connection
 */
export interface ConnectionConfig {
    user: string;
}
/**
 * Class for the config of a Pool.
 * This class is not supposed to be extended, as the framework does not expose methods to override the creation of the
 * connection pools.
 */
export interface PoolConfig<C extends ConnectionConfig> {
    max?: number;
    min?: number;
    maxWaitingClients?: number;
    testOnBorrow?: boolean;
    acquireTimeoutMillis?: number;
    evictionRunIntervalMillis?: number;
    numTestsPerRun?: number;
    softIdleTimeoutMillis?: number;
    idleTimeoutMillis?: number;
    connectionConfig?: C;
}
export declare abstract class ConnectionPool<T> {
    abstract getName(): string;
    abstract isReadonly(): boolean;
    abstract getConnection(): Promise<T>;
    abstract release(connection: T): any;
    abstract start(): Promise<void>;
    abstract stop(): Promise<void>;
}
export declare class InstrumentedFactory<T> implements Factory<T> {
    validateFailedCounter: Counter.Internal;
    connectErrorsCounter: Counter.Internal;
    connectTimeHistogram: Histogram.Internal;
    totalGauge: Gauge.Internal;
    factory: Factory<T>;
    constructor(factory: Factory<T>, name: string, readonly: boolean);
    create(): Promise<T>;
    destroy(client: T): Promise<void>;
    validate(client: T): Promise<boolean>;
}
export declare class InstrumentedConnectionPool<C, CC extends ConnectionConfig> extends ConnectionPool<C> {
    readonly: boolean;
    name: string;
    activeGauge: ExtendedGaugeInternal;
    useTimeHistogram: Histogram.Internal;
    acquireErrorsCounter: Counter.Internal;
    pool: Pool<C>;
    acquireTimeHistogram: Histogram.Internal;
    options: PoolConfig<CC>;
    private status;
    maxConnectionLimitGauge: Gauge.Internal;
    constructor(factory: Factory<C>, options: PoolConfig<CC>, name: string, readonly: boolean);
    getName(): string;
    isReadonly(): boolean;
    getConnection(): Promise<C>;
    private getGenericPoolOptions;
    release(connection: C): void;
    start(): Promise<void>;
    stop(): Promise<void>;
    getOptions(): PoolConfig<CC>;
}