/**
 * Copyright (c) 2025 Databricks Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import IClientContext from '../contracts/IClientContext';
import TelemetryClient from './TelemetryClient';
/**
 * Process-wide registry of `TelemetryClient`s, one per host. Multiple
 * `DBSQLClient` instances connecting to the same host share the same
 * `TelemetryClient`, which owns the host-scoped circuit breaker, feature
 * flag cache, exporter, and aggregator.
 *
 * Singleton because the resources we're sharing — circuit-breaker counters,
 * batched HTTP exports — are correct only at process scope. Per-`DBSQLClient`
 * provider scope (the previous design) deduplicates nothing.
 *
 * `getOrCreateClient` is sync: caller increments refcount, registers its
 * context+auth, and walks away. `releaseClient` is `async` because the
 * underlying `TelemetryClient.close()` awaits the final flush.
 */
declare class TelemetryClientProvider {
    private static instance;
    private clients;
    private softLimitWarned;
    static getInstance(): TelemetryClientProvider;
    /**
     * Reset the process-wide singleton. Test-only — name-prefixed so
     * production callsites can't reach for it accidentally via autocomplete.
     * Resetting in production drops every host's circuit-breaker counters,
     * feature-flag cache, exporter, and pending-metric buffer at once.
     *
     * @internal Test-only. Production code MUST NOT call this.
     */
    static __resetInstanceForTests(): void;
    private static normalizeHostKey;
    /**
     * Get or create the `TelemetryClient` for `host`, registering `context` as
     * a participant. Increments refcount.
     */
    getOrCreateClient(context: IClientContext, host: string): TelemetryClient;
    /**
     * Release `context`'s registration. When the last `DBSQLClient` releases,
     * the underlying `TelemetryClient.close()` runs and the entry is removed.
     */
    releaseClient(context: IClientContext, host: string): Promise<void>;
    /** @internal Exposed for testing only. */
    getRefCount(host: string): number;
    /** @internal Exposed for testing only. */
    getActiveClients(): Map<string, TelemetryClient>;
}
export default TelemetryClientProvider;