ThreadUtil.sleep(RandomUtils.nextLong(minSleep, maxSleep));
                retryCount++;
            }
        }
    }

    /**
     * Destroys the client and closes connections.
     */
    @PreDestroy
    public void destroy() {
        if (client != null) {
            try {
                client.close();
            } catch (final OpenSearchException e) {

 * request body start and end events occur within the response header events. Similarly,
 * [duplex calls][RequestBody.isDuplex] interleave the request and response bodies.
 *
 * Since connections may be reused, the proxy selection, DNS, and connect events may not be present
 * for a call. In future releases of OkHttp these events may also occur concurrently to permit
 * multiple routes to be attempted simultaneously.
 *

### Create an Engine { #create-an-engine }

A SQLModel `engine` (underneath it's actually a SQLAlchemy `engine`) is what **holds the connections** to the database.

You would have **one single `engine` object** for all your code to connect to the same database.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[14:18] hl[14:15,17:18] *}

                // SECURITY WARNING: Unsecure basic authentication is enabled by default.
                // This sends credentials in Base64 encoding over potentially unencrypted connections.
                // For production, it is STRONGLY RECOMMENDED to set spnego.allow.unsecure.basic to false
                // and use HTTPS or more secure authentication methods.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import jcifs.CIFSContext;
import jcifs.smb.SmbFile;

/**
 * SMB2/SMB3 Lease Manager
 *
 * Manages lease state for SMB2/SMB3 connections
 */
public class LeaseManager {

    private static final Logger log = LoggerFactory.getLogger(LeaseManager.class);

    private final ConcurrentHashMap<Smb2LeaseKey, LeaseEntry> leases;

     * 1 - connecting
     * 2 - connected
     * 3 - disconnecting
     */
    int connectionState;
    int uid;
    Vector trees;
    // Transport parameters allows trans to be removed from CONNECTIONS
    private final UniAddress address;
    private final int port, localPort;
    private final InetAddress localAddr;

    SmbTransport transport = null;
    NtlmPasswordAuthentication auth;

// noEvictionTTL - very long ttl to prevent eviction
const noEvictionTTL = time.Hour * 24 * 365 * 10

// because of uint8 usage for nextCleanupBucket, should not exceed 256.
// casting it as uint8 explicitly requires type conversions in multiple places
const numBuckets = 100

// NewLRU returns a new thread-safe cache with expirable entries.
//
// Size parameter set to 0 makes cache of unlimited size, e.g. turns LRU mechanism off.
//

  /**
   * Guides the allowed concurrency among update operations. Used as a hint for internal sizing. The
   * table is internally partitioned to try to permit the indicated number of concurrent updates
   * without contention. Because assignment of entries to these partitions is not necessarily
   * uniform, the actual concurrency observed may vary. Ideally, you should choose a value to

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a

import jcifs.internal.smb2.ioctl.QueryNetworkInterfaceInfoResponse;
import jcifs.internal.smb2.ioctl.Smb2IoctlRequest;
import jcifs.internal.smb2.session.Smb2SessionSetupRequest;

/**
 * Manages SMB3 Multi-Channel connections
 */
public class ChannelManager {

    private static final Logger log = LoggerFactory.getLogger(ChannelManager.class);

    private final CIFSContext context;
    private final SmbSession session;