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    * Licensed to the Apache Software Foundation (ASF) under one
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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.IOException;
  
  import org.apache.hc.client5.http.UserTokenHandler;
  import org.apache.hc.client5.http.classic.methods.HttpGet;
  import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.client5.testing.sync.extension.TestClientResources;
  import org.apache.hc.core5.http.ClassicHttpRequest;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.EndpointDetails;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpHost;
  import org.apache.hc.core5.http.HttpStatus;
  import org.apache.hc.core5.http.URIScheme;
  import org.apache.hc.core5.http.io.HttpRequestHandler;
  import org.apache.hc.core5.http.io.entity.EntityUtils;
  import org.apache.hc.core5.http.io.entity.StringEntity;
  import org.apache.hc.core5.http.protocol.BasicHttpContext;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.testing.classic.ClassicTestServer;
  import org.apache.hc.core5.util.Timeout;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.extension.RegisterExtension;
  
  /**
   * Test cases for state-ful connections.
   */
  public class TestStatefulConnManagement {
  
      public static final Timeout TIMEOUT = Timeout.ofMinutes(1);
      public static final Timeout LONG_TIMEOUT = Timeout.ofMinutes(3);
  
      @RegisterExtension
      private TestClientResources testResources = new TestClientResources(URIScheme.HTTP, TIMEOUT);
  
      private static class SimpleService implements HttpRequestHandler {
  
          public SimpleService() {
              super();
          }
  
          @Override
          public void handle(
                  final ClassicHttpRequest request,
                  final ClassicHttpResponse response,
                  final HttpContext context) throws HttpException, IOException {
              response.setCode(HttpStatus.SC_OK);
              final StringEntity entity = new StringEntity("Whatever");
              response.setEntity(entity);
          }
      }
  
      @Test
      public void testStatefulConnections() throws Exception {
          final ClassicTestServer server = testResources.startServer(null, null, null);
          server.registerHandler("*", new SimpleService());
          final HttpHost target = testResources.targetHost();
  
          final int workerCount = 5;
          final int requestCount = 5;
  
          final UserTokenHandler userTokenHandler = (route, context) -> {
              final String id = (String) context.getAttribute("user");
              return id;
          };
  
          final CloseableHttpClient client = testResources.startClient(
                  builder -> builder
                          .setMaxConnTotal(workerCount)
                          .setMaxConnPerRoute(workerCount),
                 builder -> builder
                         .setUserTokenHandler(userTokenHandler)
         );
 
         final HttpClientContext[] contexts = new HttpClientContext[workerCount];
         final HttpWorker[] workers = new HttpWorker[workerCount];
         for (int i = 0; i < contexts.length; i++) {
             final HttpClientContext context = HttpClientContext.create();
             contexts[i] = context;
             workers[i] = new HttpWorker(
                     "user" + i,
                     context, requestCount, target, client);
         }
 
         for (final HttpWorker worker : workers) {
             worker.start();
         }
         for (final HttpWorker worker : workers) {
             worker.join(LONG_TIMEOUT.toMilliseconds());
         }
         for (final HttpWorker worker : workers) {
             final Exception ex = worker.getException();
             if (ex != null) {
                 throw ex;
             }
             Assertions.assertEquals(requestCount, worker.getCount());
         }
 
         for (final HttpContext context : contexts) {
             final String state0 = (String) context.getAttribute("r0");
             Assertions.assertNotNull(state0);
             for (int r = 1; r < requestCount; r++) {
                 Assertions.assertEquals(state0, context.getAttribute("r" + r));
             }
         }
 
     }
 
     static class HttpWorker extends Thread {
 
         private final String uid;
         private final HttpClientContext context;
         private final int requestCount;
         private final HttpHost target;
         private final CloseableHttpClient httpclient;
 
         private volatile Exception exception;
         private volatile int count;
 
         public HttpWorker(
                 final String uid,
                 final HttpClientContext context,
                 final int requestCount,
                 final HttpHost target,
                 final CloseableHttpClient httpclient) {
             super();
             this.uid = uid;
             this.context = context;
             this.requestCount = requestCount;
             this.target = target;
             this.httpclient = httpclient;
             this.count = 0;
         }
 
         public int getCount() {
             return this.count;
         }
 
         public Exception getException() {
             return this.exception;
         }
 
         @Override
         public void run() {
             try {
                 this.context.setAttribute("user", this.uid);
                 for (int r = 0; r < this.requestCount; r++) {
                     final HttpGet httpget = new HttpGet("/");
                     this.httpclient.execute(this.target, httpget, this.context, response -> {
                         EntityUtils.consume(response.getEntity());
                         return null;
                     });
                     this.count++;
 
                     final EndpointDetails endpointDetails = this.context.getEndpointDetails();
                     final String connuid = Integer.toHexString(System.identityHashCode(endpointDetails));
                     this.context.setAttribute("r" + r, connuid);
                 }
 
             } catch (final Exception ex) {
                 this.exception = ex;
             }
         }
 
     }
 
     @Test
     public void testRouteSpecificPoolRecylcing() throws Exception {
         final ClassicTestServer server = testResources.startServer(null, null, null);
         server.registerHandler("*", new SimpleService());
         final HttpHost target = testResources.targetHost();
 
         // This tests what happens when a maxed connection pool needs
         // to kill the last idle connection to a route to build a new
         // one to the same route.
 
         final int maxConn = 2;
 
 
         final UserTokenHandler userTokenHandler = (route, context) -> context.getAttribute("user");
 
         final CloseableHttpClient client = testResources.startClient(
                 builder -> builder
                         .setMaxConnTotal(maxConn)
                         .setMaxConnPerRoute(maxConn),
                 builder -> builder
                         .setUserTokenHandler(userTokenHandler)
         );
 
         // Bottom of the pool : a *keep alive* connection to Route 1.
         final HttpContext context1 = new BasicHttpContext();
         context1.setAttribute("user", "stuff");
         client.execute(target, new HttpGet("/"), context1, response -> {
             EntityUtils.consume(response.getEntity());
             return null;
         });
 
         // The ConnPoolByRoute now has 1 free connection, out of 2 max
         // The ConnPoolByRoute has one RouteSpcfcPool, that has one free connection
         // for [localhost][stuff]
 
         Thread.sleep(100);
 
         // Send a very simple HTTP get (it MUST be simple, no auth, no proxy, no 302, no 401, ...)
         // Send it to another route. Must be a keepalive.
         final HttpContext context2 = new BasicHttpContext();
         client.execute(new HttpHost("127.0.0.1", server.getPort()), new HttpGet("/"), context2, response -> {
             EntityUtils.consume(response.getEntity());
             return null;
         });
         // ConnPoolByRoute now has 2 free connexions, out of its 2 max.
         // The [localhost][stuff] RouteSpcfcPool is the same as earlier
         // And there is a [127.0.0.1][null] pool with 1 free connection
 
         Thread.sleep(100);
 
         // This will put the ConnPoolByRoute to the targeted state :
         // [localhost][stuff] will not get reused because this call is [localhost][null]
         // So the ConnPoolByRoute will need to kill one connection (it is maxed out globally).
         // The killed conn is the oldest, which means the first HTTPGet ([localhost][stuff]).
         // When this happens, the RouteSpecificPool becomes empty.
         final HttpContext context3 = new BasicHttpContext();
         client.execute(target, new HttpGet("/"), context3, response -> {
             EntityUtils.consume(response.getEntity());
             return null;
         });
 
         // If the ConnPoolByRoute did not behave coherently with the RouteSpecificPool
         // this may fail. Ex : if the ConnPool discared the route pool because it was empty,
         // but still used it to build the request3 connection.
 
     }
 
 }