import { OnModuleInit } from '@nestjs/common';
import { Connection } from 'mongoose';
/**
 * LockService
 *
 * This service manages distributed locks using MongoDB. Each lock is uniquely identified by a `lockKey`
 * and associated with a service via `serviceId`. Locks ensure that only one service instance can perform
 * operations on a given resource at any time. Locks are automatically released after a specified timeout
 * to prevent deadlocks.
 */
export declare class LockService implements OnModuleInit {
    private readonly databaseConnection;
    private readonly logger;
    private readonly lockModel;
    private readonly serviceId;
    private readonly lockDuration;
    /**
     * Initializes the LockService with an injected MongoDB connection.
     * Sets up the lock model based on the Lock schema.
     *
     * @param databaseConnection Injected Mongoose connection instance.
     */
    constructor(databaseConnection: Connection);
    /**
     * Ensures the lock model indexes and schema are initialized after module setup.
     */
    onModuleInit(): Promise<void>;
    /**
     * Attempts to acquire a distributed lock for the given key.
     *
     * The lock is acquired only if:
     * - No current lock exists for the key (i.e., serviceId field does not exist)
     * - Or the existing lock has expired (expiresAt less than current time)
     *
     * If successful, the lock document is created or updated with the current serviceId
     * and a new expiration timestamp.
     *
     * This atomic operation avoids race conditions where multiple services
     * attempt to acquire the same lock simultaneously.
     *
     * @param lockKey Unique identifier for the resource to lock.
     * @returns True if the lock was acquired successfully; false otherwise.
     */
    acquireLock(lockKey: string): Promise<boolean>;
    /**
     * Releases the lock for the specified key, but only if currently owned by this service instance.
     *
     * This prevents accidentally releasing locks held by other services.
     *
     * @param lockKey Unique identifier for the lock to release.
     */
    releaseLock(lockKey: string): Promise<void>;
}