TestStatefulConnManagement

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package org.apache.http.impl.client.integration;

import java.io.IOException;

import org.apache.http.HttpClientConnection;
import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.UserTokenHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.entity.StringEntity;
import org.apache.http.localserver.LocalServerTestBase;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.HttpRequestHandler;
import org.apache.http.util.EntityUtils;
import org.junit.Assert;
import org.junit.Test;

/**
 * Test cases for state-ful connections.
 */
public class TestStatefulConnManagement extends LocalServerTestBase {

    private static class SimpleService implements HttpRequestHandler {

        public SimpleService() {
            super();
        }

        @Override
        public void handle(
                final HttpRequest request,
                final HttpResponse response,
                final HttpContext context) throws HttpException, IOException {
            response.setStatusCode(HttpStatus.SC_OK);
            final StringEntity entity = new StringEntity("Whatever");
            response.setEntity(entity);
        }
    }

    @Test
    public void testStatefulConnections() throws Exception {

        final int workerCount = 5;
        final int requestCount = 5;

        this.serverBootstrap.registerHandler("*", new SimpleService());

        this.connManager.setMaxTotal(workerCount);
        this.connManager.setDefaultMaxPerRoute(workerCount);

        final UserTokenHandler userTokenHandler = new UserTokenHandler() {

            @Override
            public Object getUserToken(final HttpContext context) {
                final String id = (String) context.getAttribute("user");
                return id;
            }

        };
        this.clientBuilder.setUserTokenHandler(userTokenHandler);

        final HttpHost target = start();

        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, this.httpclient);
        }

        for (final HttpWorker worker : workers) {
            worker.start();
        }
        for (final HttpWorker worker : workers) {
            worker.join(10000);
        }
        for (final HttpWorker worker : workers) {
            final Exception ex = worker.getException();
            if (ex != null) {
                throw ex;
            }
            Assert.assertEquals(requestCount, worker.getCount());
        }

        for (final HttpContext context : contexts) {
            final String uid = (String) context.getAttribute("user");

            for (int r = 0; r < requestCount; r++) {
                final String state = (String) context.getAttribute("r" + r);
                Assert.assertNotNull(state);
                Assert.assertEquals(uid, state);
            }
        }

    }

    static class HttpWorker extends Thread {

        private final String uid;
        private final HttpClientContext context;
        private final int requestCount;
        private final HttpHost target;
        private final HttpClient httpclient;

        private volatile Exception exception;
        private volatile int count;

        public HttpWorker(
                final String uid,
                final HttpClientContext context,
                final int requestCount,
                final HttpHost target,
                final HttpClient 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("/");
                    final HttpResponse response = this.httpclient.execute(
                            this.target,
                            httpget,
                            this.context);
                    this.count++;

                    final HttpClientConnection conn = this.context.getConnection(HttpClientConnection.class);
                    final HttpContext connContext = (HttpContext) conn;
                    String connuid = (String) connContext.getAttribute("user");
                    if (connuid == null) {
                        connContext.setAttribute("user", this.uid);
                        connuid = this.uid;
                    }
                    this.context.setAttribute("r" + r, connuid);
                    EntityUtils.consume(response.getEntity());
                }

            } catch (final Exception ex) {
                this.exception = ex;
            }
        }

    }

    @Test
    public void testRouteSpecificPoolRecylcing() throws Exception {
        // 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;

        this.serverBootstrap.registerHandler("*", new SimpleService());

        this.connManager.setMaxTotal(maxConn);
        this.connManager.setDefaultMaxPerRoute(maxConn);

        final UserTokenHandler userTokenHandler = new UserTokenHandler() {

            @Override
            public Object getUserToken(final HttpContext context) {
                return context.getAttribute("user");
            }

        };

        this.clientBuilder.setUserTokenHandler(userTokenHandler);

        final HttpHost target = start();

        // Bottom of the pool : a *keep alive* connection to Route 1.
        final HttpContext context1 = new BasicHttpContext();
        context1.setAttribute("user", "stuff");
        final HttpResponse response1 = this.httpclient.execute(
                target, new HttpGet("/"), context1);
        EntityUtils.consume(response1.getEntity());

        // 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();
        final HttpResponse response2 = this.httpclient.execute(
                new HttpHost("127.0.0.1", this.server.getLocalPort()), new HttpGet("/"), context2);
        EntityUtils.consume(response2.getEntity());
        // 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();
        final HttpResponse response3 = this.httpclient.execute(
                target, new HttpGet("/"), context3);

        // 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.
        EntityUtils.consume(response3.getEntity());

    }

}