import type { Sql } from "postgres";
import { type AcquireResult, type KeyOp } from "../../common/backend.js";
import type { PostgresCapabilities, PostgresConfig } from "../types.js";
/**
 * Creates PostgreSQL acquire operation with atomic transaction.
 *
 * Transaction flow:
 * 1. Acquire advisory lock on storage key (serializes concurrent acquires)
 * 2. Get server time
 * 3. Check if lock exists and is live
 * 4. If live, return contention
 * 5. Increment fence counter atomically using two-step pattern:
 *    a. INSERT ... ON CONFLICT DO NOTHING (ensures row exists)
 *    b. UPDATE ... RETURNING (implicit row lock serializes concurrent increments)
 *    This pattern prevents absent-row race where multiple clients both see
 *    missing row and both insert fence=1.
 * 6. Insert/update lock with new lockId and fence
 * 7. Return success with authoritative server-time expiresAtMs
 * 8. Advisory lock automatically released on transaction commit
 *
 * @param sql - postgres.js SQL instance
 * @param config - PostgreSQL backend configuration
 * @returns Acquire operation function
 */
export declare function createAcquireOperation(sql: Sql, config: PostgresConfig): (opts: KeyOp & {
    ttlMs: number;
}) => Promise<AcquireResult<PostgresCapabilities>>;