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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.http.impl.client.cache;
28  
29  import org.apache.http.annotation.ThreadSafe;
30  
31  import java.util.concurrent.ArrayBlockingQueue;
32  import java.util.concurrent.ExecutorService;
33  import java.util.concurrent.ThreadPoolExecutor;
34  import java.util.concurrent.TimeUnit;
35  
36  /**
37   * Immediately schedules any incoming validation request. Relies on
38   * {@link CacheConfig} to configure the used {@link java.util.concurrent.ThreadPoolExecutor}.
39   *
40   * @since 4.3
41   */
42  @ThreadSafe
43  public class ImmediateSchedulingStrategy implements SchedulingStrategy {
44  
45      private final ExecutorService executor;
46  
47      /**
48       * Uses a {@link java.util.concurrent.ThreadPoolExecutor} which is configured according to the
49       * given {@link CacheConfig}.
50       * @param cacheConfig specifies thread pool settings. See
51       * {@link CacheConfig#getAsynchronousWorkersMax()},
52       * {@link CacheConfig#getAsynchronousWorkersCore()},
53       * {@link CacheConfig#getAsynchronousWorkerIdleLifetimeSecs()},
54       * and {@link CacheConfig#getRevalidationQueueSize()}.
55       */
56      public ImmediateSchedulingStrategy(final CacheConfig cacheConfig) {
57          this(new ThreadPoolExecutor(
58                  cacheConfig.getAsynchronousWorkersCore(),
59                  cacheConfig.getAsynchronousWorkersMax(),
60                  cacheConfig.getAsynchronousWorkerIdleLifetimeSecs(),
61                  TimeUnit.SECONDS,
62                  new ArrayBlockingQueue<Runnable>(cacheConfig.getRevalidationQueueSize()))
63          );
64      }
65  
66      ImmediateSchedulingStrategy(final ExecutorService executor) {
67          this.executor = executor;
68      }
69  
70      public void schedule(final AsynchronousValidationRequest revalidationRequest) {
71          if (revalidationRequest == null) {
72              throw new IllegalArgumentException("AsynchronousValidationRequest may not be null");
73          }
74  
75          executor.execute(revalidationRequest);
76      }
77  
78      public void close() {
79          executor.shutdown();
80      }
81  
82      /**
83       * Visible for testing.
84       */
85      void awaitTermination(final long timeout, final TimeUnit unit) throws InterruptedException {
86          executor.awaitTermination(timeout, unit);
87      }
88  }