io.confluent.kafka.connect.syslog.source.HostnameResolverImpl.java Source code

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Here is the source code for io.confluent.kafka.connect.syslog.source.HostnameResolverImpl.java

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/**
 * Copyright  2016 Jeremy Custenborder (jcustenborder@gmail.com)
 *
 * Licensed 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "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.
 */
package io.confluent.kafka.connect.syslog.source;

import com.google.common.base.Preconditions;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.google.common.util.concurrent.UncheckedExecutionException;
import io.confluent.kafka.connect.syslog.source.config.BaseSyslogSourceConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

public class HostnameResolverImpl implements HostnameResolver {
    private static final Logger log = LoggerFactory.getLogger(HostnameResolverImpl.class);
    final BaseSyslogSourceConfig config;
    final Cache<InetAddress, InetSocketAddress> reverseDnsCache;

    public HostnameResolverImpl(BaseSyslogSourceConfig config) {
        this.config = config;
        reverseDnsCache = CacheBuilder.newBuilder()
                .expireAfterWrite(this.config.reverseDnsCacheTtl(), TimeUnit.MILLISECONDS).recordStats().build();
    }

    @Override

    public InetSocketAddress resolve(SocketAddress socketAddress) {
        Preconditions.checkNotNull(socketAddress, "socketAddress should not be null.");
        Preconditions.checkState(socketAddress instanceof InetSocketAddress,
                "socketAddress should be InetSocketAddress.");
        final InetSocketAddress inetSocketAddress = (InetSocketAddress) socketAddress;

        try {
            return reverseDnsCache.get(inetSocketAddress.getAddress(), new Callable<InetSocketAddress>() {
                @Override
                public InetSocketAddress call() throws Exception {
                    String hostname = inetSocketAddress.getHostName();

                    if (inetSocketAddress.isUnresolved()) {
                        throw new IllegalStateException(
                                String.format("Could not resolve %s", inetSocketAddress.getAddress()));
                    }

                    if (log.isDebugEnabled()) {
                        log.debug("Resolved {} to {}. Caching result", inetSocketAddress.getAddress(), hostname);
                    }
                    return inetSocketAddress;
                }
            });
        } catch (UncheckedExecutionException ex) {
            if (log.isDebugEnabled()) {
                log.debug("Could not resolve {}.", inetSocketAddress.getAddress(), ex.getCause());
            }
            return inetSocketAddress;
        } catch (ExecutionException e) {
            if (log.isWarnEnabled()) {
                log.warn("Exception thrown while resolving ip for {}", inetSocketAddress.getAddress(), e);
            }
            return inetSocketAddress;
        }
    }
}