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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  package org.apache.hc.core5.pool;
28  
29  import java.util.concurrent.Future;
30  
31  import org.apache.hc.core5.concurrent.FutureCallback;
32  import org.apache.hc.core5.io.GracefullyCloseable;
33  import org.apache.hc.core5.util.Timeout;
34  
35  /**
36   * {@code ConnPool} represents a shared pool connections can be leased from
37   * and released back to.
38   *
39   * @param <T> the route type that represents the opposite endpoint of a pooled
40   *   connection.
41   * @param <C> the type of pooled connections.
42   * @since 4.2
43   */
44  public interface ConnPool<T, C extends GracefullyCloseable> {
45  
46      /**
47       * Attempts to lease a connection for the given route and with the given
48       * state from the pool.
49       *
50       * @param route route of the connection.
51       * @param state arbitrary object that represents a particular state
52       *  (usually a security principal or a unique token identifying
53       *  the user whose credentials have been used while establishing the connection).
54       *  May be {@code null}.
55       * @param requestTimeout request timeout.
56       * @param callback operation completion callback.
57       *
58       * @return future for a leased pool entry.
59       */
60      Future<PoolEntry<T, C>> lease(T route, Object state, Timeout requestTimeout, FutureCallback<PoolEntry<T, C>> callback);
61  
62      /**
63       * Releases the pool entry back to the pool.
64       *
65       * @param entry pool entry leased from the pool
66       * @param reusable flag indicating whether or not the released connection
67       *   is in a consistent state and is safe for further use.
68       */
69      void release(PoolEntry<T, C> entry, boolean reusable);
70  
71  }