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    * Licensed to the Apache Software Foundation (ASF) under one
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    * distributed with this work for additional information
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    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
   *
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   *
   * Unless required by applicable law or agreed to in writing,
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   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
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   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
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  package org.apache.hc.client5.testing.sync;
  
  import java.io.ByteArrayInputStream;
  import java.io.IOException;
  import java.net.URI;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hc.client5.http.classic.methods.HttpGet;
  import org.apache.hc.client5.http.classic.methods.HttpPost;
  import org.apache.hc.client5.http.classic.methods.HttpUriRequestBase;
  import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.ContentType;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HeaderElements;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpHost;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.HttpResponseInterceptor;
  import org.apache.hc.core5.http.impl.HttpProcessors;
  import org.apache.hc.core5.http.io.entity.EntityUtils;
  import org.apache.hc.core5.http.io.entity.InputStreamEntity;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.http.protocol.HttpProcessor;
  import org.junit.Assert;
  import org.junit.Test;
  
  public class TestConnectionReuse extends LocalServerTestBase {
  
      @Test
      public void testReuseOfPersistentConnections() throws Exception {
          this.connManager.setMaxTotal(5);
          this.connManager.setDefaultMaxPerRoute(5);
  
          final HttpHost target = start();
  
          final WorkerThread[] workers = new WorkerThread[10];
          for (int i = 0; i < workers.length; i++) {
              workers[i] = new WorkerThread(
                      this.httpclient,
                      target,
                      new URI("/random/2000"),
                      10, false);
          }
  
          for (final WorkerThread worker : workers) {
              worker.start();
          }
          for (final WorkerThread worker : workers) {
              worker.join(10000);
              final Exception ex = worker.getException();
              if (ex != null) {
                  throw ex;
              }
          }
  
          // Expect some connection in the pool
          Assert.assertTrue(this.connManager.getTotalStats().getAvailable() > 0);
      }
  
      @Test
      public void testReuseOfPersistentConnectionsWithStreamedRequestAndResponse() throws Exception {
          this.connManager.setMaxTotal(5);
          this.connManager.setDefaultMaxPerRoute(5);
  
          final HttpHost target = start();
  
          final WorkerThread[] workers = new WorkerThread[10];
         for (int i = 0; i < workers.length; i++) {
             final List<HttpUriRequestBase> requests = new ArrayList<>();
             for (int j = 0; j < 10; j++) {
                 final HttpPost post = new HttpPost(new URI("/random/2000"));
                 // non-repeatable
                 post.setEntity(new InputStreamEntity(
                         new ByteArrayInputStream("test".getBytes(StandardCharsets.UTF_8)),
                         ContentType.APPLICATION_OCTET_STREAM));
                 requests.add(post);
             }
             workers[i] = new WorkerThread(this.httpclient, target, false, requests);
         }
 
         for (final WorkerThread worker : workers) {
             worker.start();
         }
         for (final WorkerThread worker : workers) {
             worker.join(10000);
             final Exception ex = worker.getException();
             if (ex != null) {
                 throw ex;
             }
         }
 
         // Expect some connection in the pool
         Assert.assertTrue(this.connManager.getTotalStats().getAvailable() > 0);
     }
 
     private static class AlwaysCloseConn implements HttpResponseInterceptor {
 
         @Override
         public void process(
                 final HttpResponse response,
                 final EntityDetails entityDetails,
                 final HttpContext context) throws HttpException, IOException {
             response.setHeader(HttpHeaders.CONNECTION, HeaderElements.CLOSE);
         }
 
     }
 
     @Test
     public void testReuseOfClosedConnections() throws Exception {
         this.connManager.setMaxTotal(5);
         this.connManager.setDefaultMaxPerRoute(5);
 
         final HttpProcessor httpproc = HttpProcessors.customServer(null)
                 .add(new AlwaysCloseConn())
                 .build();
         final HttpHost target = start(httpproc, null);
 
         final WorkerThread[] workers = new WorkerThread[10];
         for (int i = 0; i < workers.length; i++) {
             workers[i] = new WorkerThread(
                     this.httpclient,
                     target,
                     new URI("/random/2000"),
                     10, false);
         }
 
         for (final WorkerThread worker : workers) {
             worker.start();
         }
         for (final WorkerThread worker : workers) {
             worker.join(10000);
             final Exception ex = worker.getException();
             if (ex != null) {
                 throw ex;
             }
         }
 
         // Expect zero connections in the pool
         Assert.assertEquals(0, this.connManager.getTotalStats().getAvailable());
     }
 
     @Test
     public void testReuseOfAbortedConnections() throws Exception {
         this.connManager.setMaxTotal(5);
         this.connManager.setDefaultMaxPerRoute(5);
 
         final HttpHost target = start();
 
         final WorkerThread[] workers = new WorkerThread[10];
         for (int i = 0; i < workers.length; i++) {
             workers[i] = new WorkerThread(
                     this.httpclient,
                     target,
                     new URI("/random/2000"),
                     10, true);
         }
 
         for (final WorkerThread worker : workers) {
             worker.start();
         }
         for (final WorkerThread worker : workers) {
             worker.join(10000);
             final Exception ex = worker.getException();
             if (ex != null) {
                 throw ex;
             }
         }
 
         // Expect zero connections in the pool
         Assert.assertEquals(0, this.connManager.getTotalStats().getAvailable());
     }
 
     @Test
     public void testKeepAliveHeaderRespected() throws Exception {
         this.connManager.setMaxTotal(1);
         this.connManager.setDefaultMaxPerRoute(1);
 
         final HttpProcessor httpproc = HttpProcessors.customServer(null)
                 .add(new ResponseKeepAlive())
                 .build();
         final HttpHost target = start(httpproc, null);
 
         ClassicHttpResponse response = this.httpclient.execute(target, new HttpGet("/random/2000"));
         EntityUtils.consume(response.getEntity());
 
         Assert.assertEquals(1, this.connManager.getTotalStats().getAvailable());
 
         response = this.httpclient.execute(target, new HttpGet("/random/2000"));
         EntityUtils.consume(response.getEntity());
 
         Assert.assertEquals(1, this.connManager.getTotalStats().getAvailable());
 
         // Now sleep for 1.1 seconds and let the timeout do its work
         Thread.sleep(1100);
         response = this.httpclient.execute(target, new HttpGet("/random/2000"));
         EntityUtils.consume(response.getEntity());
 
         Assert.assertEquals(1, this.connManager.getTotalStats().getAvailable());
 
         // Do another request just under the 1 second limit & make
         // sure we reuse that connection.
         Thread.sleep(500);
         response = this.httpclient.execute(target, new HttpGet("/random/2000"));
         EntityUtils.consume(response.getEntity());
 
         Assert.assertEquals(1, this.connManager.getTotalStats().getAvailable());
     }
 
     private static class WorkerThread extends Thread {
 
         private final HttpHost target;
         private final CloseableHttpClient httpclient;
         private final boolean forceClose;
         private final List<HttpUriRequestBase> requests;
 
         private volatile Exception exception;
 
         public WorkerThread(
                 final CloseableHttpClient httpclient,
                 final HttpHost target,
                 final URI requestURI,
                 final int repetitions,
                 final boolean forceClose) {
             super();
             this.httpclient = httpclient;
             this.target = target;
             this.forceClose = forceClose;
             this.requests = new ArrayList<>(repetitions);
             for (int i = 0; i < repetitions; i++) {
                 requests.add(new HttpGet(requestURI));
             }
         }
 
         public WorkerThread(
                 final CloseableHttpClient httpclient,
                 final HttpHost target,
                 final boolean forceClose,
                 final List<HttpUriRequestBase> requests) {
             super();
             this.httpclient = httpclient;
             this.target = target;
             this.forceClose = forceClose;
             this.requests = requests;
         }
 
         @Override
         public void run() {
             try {
                 for (final HttpUriRequestBase request : requests) {
                     final ClassicHttpResponse response = this.httpclient.execute(
                             this.target,
                             request);
                     if (this.forceClose) {
                         request.cancel();
                     } else {
                         EntityUtils.consume(response.getEntity());
                     }
                 }
             } catch (final Exception ex) {
                 this.exception = ex;
             }
         }
 
         public Exception getException() {
             return exception;
         }
 
     }
 
     // A very basic keep-alive header interceptor, to add Keep-Alive: timeout=1
     // if there is no Connection: close header.
     private static class ResponseKeepAlive implements HttpResponseInterceptor {
         @Override
         public void process(
                 final HttpResponse response,
                 final EntityDetails entityDetails,
                 final HttpContext context) throws HttpException, IOException {
             final Header connection = response.getFirstHeader(HttpHeaders.CONNECTION);
             if(connection != null) {
                 if(!connection.getValue().equalsIgnoreCase("Close")) {
                     response.addHeader(HeaderElements.KEEP_ALIVE, "timeout=1");
                 }
             }
         }
     }
 
 }