/**
* 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.mapred;
/**
* Represents the level of data-locality at which a job in the fair scheduler
* is allowed to launch tasks. By default, jobs are not allowed to launch
* non-data-local tasks until they have waited a small number of seconds to
* find a slot on a node that they have data on. If a job has waited this
* long, it is allowed to launch other locality tasks as well, such as:
* nodegroup-local if the topology support nodegroup layer, rack-local (on
* nodes that may not have the task's input data, but share a rack with a node
* that does). Finally, after a further wait, jobs are allowed to launch tasks
* anywhere in the cluster.
*
* This enum defines four levels - NODE, NODEGROUP, RACK and ANY (for allowing
* tasks to be launched on any node). A map task's level can be obtained from
* its job through {@link #fromTask(JobInProgress, Task, TaskTrackerStatus)}. In
* addition, for any locality level, it is possible to get a "level cap" to pass
* to {@link JobInProgress#obtainNewMapTask(TaskTrackerStatus, int, int, int)}
* to ensure that only tasks at this level or lower are launched, through
* the {@link #toCacheLevelCap()} method.
*/
public enum LocalityLevel {
NODE, NODEGROUP, RACK, ANY;
public static LocalityLevel fromTask(JobInProgress job, Task mapTask,
TaskTrackerStatus tracker, boolean isNodeGroupAware) {
TaskID tipID = mapTask.getTaskID().getTaskID();
TaskInProgress tip = job.getTaskInProgress(tipID);
if (isNodeGroupAware) {
switch (job.getLocalityLevel(tip, tracker)) {
case 0: return LocalityLevel.NODE;
case 1: return LocalityLevel.NODEGROUP;
case 2: return LocalityLevel.RACK;
default: return LocalityLevel.ANY;
}
} else {
switch (job.getLocalityLevel(tip, tracker)) {
case 0: return LocalityLevel.NODE;
case 1: return LocalityLevel.RACK;
default: return LocalityLevel.ANY;
}
}
}
/**
* Obtain a JobInProgress cache level cap to pass to
* {@link JobInProgress#obtainNewMapTask(TaskTrackerStatus, int, int, int)}
* to ensure that only tasks of this locality level and lower are launched.
*/
public int toCacheLevelCap(boolean isNodeGroupAware) {
if (isNodeGroupAware) {
switch(this) {
case NODE: return 1;
case NODEGROUP: return 2;
case RACK: return 3;
default: return Integer.MAX_VALUE;
}
} else {
switch(this) {
case NODE: return 1;
case RACK: return 2;
default: return Integer.MAX_VALUE;
}
}
}
}