org.apache.hadoop.hdfs.server.blockmanagement.FSClusterStats 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.server.blockmanagement;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* This interface is used for retrieving the load related statistics of
* the cluster.
*/
@InterfaceAudience.Private
public interface FSClusterStats {
/**
* an indication of the total load of the cluster.
*
* @return a count of the total number of block transfers and block
* writes that are currently occuring on the cluster.
*/
public int getTotalLoad();
/**
* Indicate whether or not the cluster is now avoiding
* to use stale DataNodes for writing.
*
* @return True if the cluster is currently avoiding using stale DataNodes
* for writing targets, and false otherwise.
*/
public boolean isAvoidingStaleDataNodesForWrite();
/**
* Indicates number of datanodes that are in service.
* @return Number of datanodes that are both alive and not decommissioned.
*/
public int getNumDatanodesInService();
/**
* an indication of the average load of non-decommission(ing|ed) nodes
* eligible for block placement
*
* @return average of the in service number of block transfers and block
* writes that are currently occurring on the cluster.
*/
public double getInServiceXceiverAverage();
}