org.apache.hadoop.hdfs.client.HdfsUtils Maven / Gradle / Ivy
/**
* 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.client;
import java.io.IOException;
import java.net.URI;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The public utility API for HDFS.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class HdfsUtils {
public static final Logger LOG = LoggerFactory.getLogger(HdfsUtils.class);
/**
* Is the HDFS healthy?
* HDFS is considered as healthy if it is up and not in safemode.
*
* @param uri the HDFS URI. Note that the URI path is ignored.
* @return true if HDFS is healthy; false, otherwise.
*/
public static boolean isHealthy(URI uri) {
//check scheme
final String scheme = uri.getScheme();
if (!HdfsConstants.HDFS_URI_SCHEME.equalsIgnoreCase(scheme)) {
throw new IllegalArgumentException("The scheme is not "
+ HdfsConstants.HDFS_URI_SCHEME + ", uri=" + uri);
}
final Configuration conf = new Configuration();
//disable FileSystem cache
conf.setBoolean(String.format("fs.%s.impl.disable.cache", scheme), true);
//disable client retry for rpc connection and rpc calls
conf.setBoolean(HdfsClientConfigKeys.Retry.POLICY_ENABLED_KEY, false);
conf.setInt(
CommonConfigurationKeysPublic.IPC_CLIENT_CONNECT_MAX_RETRIES_KEY, 0);
DistributedFileSystem fs = null;
try {
fs = (DistributedFileSystem)FileSystem.get(uri, conf);
final boolean safemode = fs.setSafeMode(SafeModeAction.SAFEMODE_GET);
if (LOG.isDebugEnabled()) {
LOG.debug("Is namenode in safemode? " + safemode + "; uri=" + uri);
}
fs.close();
fs = null;
return !safemode;
} catch(IOException e) {
if (LOG.isDebugEnabled()) {
LOG.debug("Got an exception for uri=" + uri, e);
}
return false;
} finally {
IOUtils.closeQuietly(fs);
}
}
}