experiment testing Apache HttpAsyncClient HttpCache behaviour

CachingCloseableHttpAsyncClientTest.java

package de.porsche.pcc.instrumentation;

import com.github.tomakehurst.wiremock.client.WireMock;
import com.github.tomakehurst.wiremock.junit.WireMockRule;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.HttpException;
import org.apache.http.HttpHeaders;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;
import org.apache.http.client.cache.CacheResponseStatus;
import org.apache.http.client.cache.HttpCacheContext;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.DateUtils;
import org.apache.http.impl.client.cache.BasicHttpCacheStorage;
import org.apache.http.impl.client.cache.CacheConfig;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.protocol.HttpContext;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;

import java.io.IOException;
import java.net.URI;
import java.util.Date;

import static org.hamcrest.Matchers.equalTo;
import static org.junit.Assert.assertThat;

/**
 * @author Erich Eichinger
 * @since 06/10/16
 */
@Slf4j
public class CachingCloseableHttpAsyncClientTest {

    @Rule
    public WireMockRule wireMockRule = new WireMockRule(0);

    CloseableHttpAsyncClient client;

    @Before
    public void before() {
        client = HttpAsyncClientBuilder
            .create()
            .setMaxConnPerRoute(10)
            .setMaxConnTotal(10)
                // ensure we set a date on the response, otherwise for 304 responses, Apache HttpCache miscalculates the age
                // of a CacheEntry from the original 200 response's date instead of the 304 response's.
            .addInterceptorFirst(new HttpResponseInterceptor() {
                @Override
                public void process(HttpResponse response, HttpContext context) throws HttpException, IOException {
                    if (!response.containsHeader("Date")) {
                        response.addHeader(HttpHeaders.DATE, DateUtils.formatDate(new Date(System.currentTimeMillis())));
                    }
                }
            })
            .build();
        final BasicHttpCacheStorage httpCacheStorage = new BasicHttpCacheStorage(CacheConfig.custom().setMaxCacheEntries(CacheConfig.DEFAULT_MAX_CACHE_ENTRIES).build());
        final CacheConfig cacheConfig = CacheConfig
            .custom()
            .setSharedCache(true)
            .setAsynchronousWorkersCore(10)
            .setAsynchronousWorkersMax(100)
            .setAsynchronousWorkerIdleLifetimeSecs(10)
            .build();
        client = new CachingCloseableHttpAsyncClient(
            client
            , httpCacheStorage
            , cacheConfig
        );
        client.start();
    }

    @After
    public void after() throws Exception {
        client.close();
    }

    @Test
    public void handles_cacheable_responses() throws Exception {
        HttpGet httpGet = new HttpGet(new URI("http://localhost:" + wireMockRule.port() + "/foo"));

        WireMock.stubFor(WireMock
                .get(WireMock.urlMatching("/foo"))
                .willReturn(WireMock
                        .aResponse()
                        .withStatus(200)
                        .withHeader(HttpHeaders.CACHE_CONTROL, "public, max-age=1")
                        .withHeader("Content-Type", "text/plain")
                        .withHeader(HttpHeaders.ETAG, "xyz")
                        .withBody("data")
                )
        );
        WireMock.stubFor(WireMock
                .get(WireMock.urlMatching("/foo"))
                .withHeader(HttpHeaders.IF_NONE_MATCH, WireMock.equalTo("xyz"))
                .willReturn(WireMock
                        .aResponse()
                        .withStatus(304)
                )
        );

        HttpCacheContext context;

        // 1. request CACHE_MISS
        // 2. request CACHE_HIT
        // 3. request triggers revalidation with server -> VALIDATED
        // 4. request is a CACHE_HIT - item has been revalidated with server and got a 304 Response
        // 5. request is a CACHE_HIT
        // 6. request triggers revalidation with server again -> VALIDATED
        // 7. request is a CACHE_HIT - item has been revalidated with server and got a 304 Response

        context = syncExecute(httpGet); // 1
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.CACHE_MISS));
        Thread.sleep(500);
        context = syncExecute(httpGet); // 2
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.CACHE_HIT));
        Thread.sleep(600);
        context = syncExecute(httpGet); // 3
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.VALIDATED));
        Thread.sleep(100);
        context = syncExecute(httpGet); // 4
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.CACHE_HIT));
        Thread.sleep(100);
        context = syncExecute(httpGet); // 5
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.CACHE_HIT));
        Thread.sleep(800);
        context = syncExecute(httpGet); // 6
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.VALIDATED));
        Thread.sleep(100);
        context = syncExecute(httpGet); // 7
        assertThat(context.getCacheResponseStatus(), equalTo(CacheResponseStatus.CACHE_HIT));

        WireMock.verify(3, WireMock.getRequestedFor(WireMock.urlEqualTo("/foo")));
    }

    @SneakyThrows
    private HttpCacheContext syncExecute(HttpGet httpGet) throws InterruptedException, java.util.concurrent.ExecutionException {
        final HttpCacheContext context = HttpCacheContext.create();
        CloseableHttpResponse response = (CloseableHttpResponse) client.execute(httpGet, context, null).get();
        response.close();
        return context;
    }

}