import static java.util.Objects.requireNonNull;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
import static java.util.logging.Level.SEVERE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.AbstractFuture.Listener;

import java.security.cert.CertificateException
import java.security.cert.X509Certificate
import java.util.concurrent.atomic.AtomicInteger
import java.util.logging.Handler
import java.util.logging.Level
import java.util.logging.LogRecord
import java.util.logging.Logger
import javax.net.ssl.HostnameVerifier
import javax.net.ssl.SSLPeerUnverifiedException
import javax.net.ssl.SSLSocket
import javax.net.ssl.TrustManagerFactory

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.io.CloseableUtil;
import org.codelibs.core.io.CopyUtil;
import org.codelibs.core.io.FileUtil;
import org.codelibs.fess.crawler.entity.ExtractData;

 * 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.
 */
package okhttp3.logging

import java.io.IOException
import java.net.InetAddress
import java.net.InetSocketAddress
import java.net.Proxy
import java.util.concurrent.TimeUnit
import okhttp3.Call
import okhttp3.Connection

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.query;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.FuzzyQuery;
import org.apache.lucene.search.Query;
import org.codelibs.fess.Constants;

 */
package org.codelibs.fess.helper;

import java.io.IOException;

import org.apache.commons.text.StringEscapeUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.stream.StreamUtil;
import org.codelibs.curl.Curl;
import org.codelibs.curl.CurlResponse;

 */
package org.codelibs.fess.crawler.extractor.impl;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.InputStream;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.io.CloseableUtil;
import org.codelibs.core.io.ResourceUtil;
import org.codelibs.fess.crawler.container.StandardCrawlerContainer;

This can be very useful for setting up **resources** that you need to use for the whole app, and that are **shared** among requests, and/or that you need to **clean up** afterwards. For example, a database connection pool, or loading a shared machine learning model.

## Use Case { #use-case }

Let's start with an example **use case** and then see how to solve it with this.

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.BiConsumer;

import org.apache.commons.lang3.StringUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.misc.Pair;
import org.codelibs.core.stream.StreamUtil;
import org.codelibs.fess.mylasta.direction.FessConfig;

 */
package org.codelibs.fess.app.web.api.admin.joblog;

import java.util.List;
import java.util.stream.Collectors;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.fess.app.pager.JobLogPager;
import org.codelibs.fess.app.service.JobLogService;
import org.codelibs.fess.app.web.api.ApiResult;