org.apache.hadoop.hdfs.DomainSocketFactory.java Source code

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Here is the source code for org.apache.hadoop.hdfs.DomainSocketFactory.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * 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
 *
 *     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 org.apache.hadoop.hdfs;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.concurrent.TimeUnit;

import org.apache.commons.io.IOUtils;
import org.apache.commons.logging.Log;
import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.hdfs.DFSClient.Conf;
import org.apache.hadoop.net.unix.DomainSocket;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

class DomainSocketFactory {
    private static final Log LOG = BlockReaderLocal.LOG;
    private final Conf conf;

    enum PathStatus {
        UNUSABLE, SHORT_CIRCUIT_DISABLED,
    }

    /**
     * Information about domain socket paths.
     */
    Cache<String, PathStatus> pathInfo = CacheBuilder.newBuilder().expireAfterWrite(10, TimeUnit.MINUTES).build();

    public DomainSocketFactory(Conf conf) {
        this.conf = conf;

        final String feature;
        if (conf.shortCircuitLocalReads && (!conf.useLegacyBlockReaderLocal)) {
            feature = "The short-circuit local reads feature";
        } else if (conf.domainSocketDataTraffic) {
            feature = "UNIX domain socket data traffic";
        } else {
            feature = null;
        }

        if (feature == null) {
            LOG.debug("Both short-circuit local reads and UNIX domain socket are disabled.");
        } else {
            if (conf.domainSocketPath.isEmpty()) {
                throw new HadoopIllegalArgumentException(
                        feature + " is enabled but " + DFSConfigKeys.DFS_DOMAIN_SOCKET_PATH_KEY + " is not set.");
            } else if (DomainSocket.getLoadingFailureReason() != null) {
                LOG.warn(feature + " cannot be used because " + DomainSocket.getLoadingFailureReason());
            } else {
                LOG.debug(feature + " is enabled.");
            }
        }
    }

    /**
     * Create a DomainSocket.
     * 
     * @param addr        The address of the DataNode
     * @param stream      The DFSInputStream the socket will be created for.
     *
     * @return            null if the socket could not be created; the
     *                    socket otherwise.  If there was an error while
     *                    creating the socket, we will add the socket path
     *                    to our list of failed domain socket paths.
     */
    DomainSocket create(InetSocketAddress addr, DFSInputStream stream) {
        // If there is no domain socket path configured, we can't use domain
        // sockets.
        if (conf.domainSocketPath.isEmpty())
            return null;
        // If we can't do anything with the domain socket, don't create it.
        if (!conf.domainSocketDataTraffic && (!conf.shortCircuitLocalReads || conf.useLegacyBlockReaderLocal)) {
            return null;
        }
        // UNIX domain sockets can only be used to talk to local peers
        if (!DFSClient.isLocalAddress(addr))
            return null;
        // If the DomainSocket code is not loaded, we can't create
        // DomainSocket objects.
        if (DomainSocket.getLoadingFailureReason() != null)
            return null;
        String escapedPath = DomainSocket.getEffectivePath(conf.domainSocketPath, addr.getPort());
        PathStatus info = pathInfo.getIfPresent(escapedPath);
        if (info == PathStatus.UNUSABLE) {
            // We tried to connect to this domain socket before, and it was totally
            // unusable.
            return null;
        }
        if ((!conf.domainSocketDataTraffic)
                && ((info == PathStatus.SHORT_CIRCUIT_DISABLED) || stream.shortCircuitForbidden())) {
            // If we don't want to pass data over domain sockets, and we don't want
            // to pass file descriptors over them either, we have no use for domain
            // sockets.
            return null;
        }
        boolean success = false;
        DomainSocket sock = null;
        try {
            sock = DomainSocket.connect(escapedPath);
            sock.setAttribute(DomainSocket.RECEIVE_TIMEOUT, conf.socketTimeout);
            success = true;
        } catch (IOException e) {
            LOG.warn("error creating DomainSocket", e);
            // fall through
        } finally {
            if (!success) {
                if (sock != null) {
                    IOUtils.closeQuietly(sock);
                }
                pathInfo.put(escapedPath, PathStatus.UNUSABLE);
                sock = null;
            }
        }
        return sock;
    }

    public void disableShortCircuitForPath(String path) {
        pathInfo.put(path, PathStatus.SHORT_CIRCUIT_DISABLED);
    }

    public void disableDomainSocketPath(String path) {
        pathInfo.put(path, PathStatus.UNUSABLE);
    }
}