hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/records/Resource.java

/**
 * 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.yarn.api.records;

import org.apache.commons.lang.NotImplementedException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.classification.InterfaceStability.Evolving;
import org.apache.hadoop.classification.InterfaceStability.Stable;
import org.apache.hadoop.yarn.api.ApplicationMasterProtocol;
import org.apache.hadoop.yarn.exceptions.ResourceNotFoundException;
import org.apache.hadoop.yarn.exceptions.YarnException;
import org.apache.hadoop.yarn.util.Records;

import java.util.Map;

/**
 * <p><code>Resource</code> models a set of computer resources in the 
 * cluster.</p>
 * 
 * <p>Currently it models both <em>memory</em> and <em>CPU</em>.</p>
 * 
 * <p>The unit for memory is megabytes. CPU is modeled with virtual cores
 * (vcores), a unit for expressing parallelism. A node's capacity should
 * be configured with virtual cores equal to its number of physical cores. A
 * container should be requested with the number of cores it can saturate, i.e.
 * the average number of threads it expects to have runnable at a time.</p>
 * 
 * <p>Virtual cores take integer values and thus currently CPU-scheduling is
 * very coarse.  A complementary axis for CPU requests that represents
 * processing power will likely be added in the future to enable finer-grained
 * resource configuration.</p>
 *
 * <p>Typically, applications request <code>Resource</code> of suitable
 * capability to run their component tasks.</p>
 * 
 * @see ResourceRequest
 * @see ApplicationMasterProtocol#allocate(org.apache.hadoop.yarn.api.protocolrecords.AllocateRequest)
 */
@Public
@Stable
public abstract class Resource implements Comparable<Resource> {

  @Public
  @Stable
  public static Resource newInstance(int memory, int vCores) {
    Resource resource = Records.newRecord(Resource.class);
    resource.setMemorySize(memory);
    resource.setVirtualCores(vCores);
    return resource;
  }

  @Public
  @Stable
  public static Resource newInstance(long memory, int vCores) {
    Resource resource = Records.newRecord(Resource.class);
    resource.setMemorySize(memory);
    resource.setVirtualCores(vCores);
    return resource;
  }

  @InterfaceAudience.Private
  @InterfaceStability.Unstable
  public static Resource newInstance(Resource resource) {
    Resource ret = Resource.newInstance(0, 0);
    for (Map.Entry<String, ResourceInformation> entry : resource.getResources()
        .entrySet()) {
      ret.setResourceInformation(entry.getKey(),
          ResourceInformation.newInstance(entry.getValue()));
    }
    return ret;
  }

  /**
   * This method is DEPRECATED:
   * Use {@link Resource#getMemorySize()} instead
   *
   * Get <em>memory</em> of the resource. Note - while memory has
   * never had a unit specified, all YARN configurations have specified memory
   * in MB. The assumption has been that the daemons and applications are always
   * using the same units. With the introduction of the ResourceInformation
   * class we have support for units - so this function will continue to return
   * memory but in the units of MB
   *
   * @return <em>memory</em>(in MB) of the resource
   */
  @Public
  @Deprecated
  public abstract int getMemory();

  /**
   * Get <em>memory</em> of the resource. Note - while memory has
   * never had a unit specified, all YARN configurations have specified memory
   * in MB. The assumption has been that the daemons and applications are always
   * using the same units. With the introduction of the ResourceInformation
   * class we have support for units - so this function will continue to return
   * memory but in the units of MB
   *
   * @return <em>memory</em> of the resource
   */
  @Public
  @Stable
  public long getMemorySize() {
    throw new NotImplementedException(
        "This method is implemented by ResourcePBImpl");
  }

  /**
   * Set <em>memory</em> of the resource. Note - while memory has
   * never had a unit specified, all YARN configurations have specified memory
   * in MB. The assumption has been that the daemons and applications are always
   * using the same units. With the introduction of the ResourceInformation
   * class we have support for units - so this function will continue to set
   * memory but the assumption is that the value passed is in units of MB.
   *
   * @param memory <em>memory</em>(in MB) of the resource
   */
  @Public
  @Deprecated
  public abstract void setMemory(int memory);

  /**
   * Set <em>memory</em> of the resource.
   * @param memory <em>memory</em> of the resource
   */
  @Public
  @Stable
  public void setMemorySize(long memory) {
    throw new NotImplementedException(
        "This method is implemented by ResourcePBImpl");
  }


  /**
   * Get <em>number of virtual cpu cores</em> of the resource.
   * 
   * Virtual cores are a unit for expressing CPU parallelism. A node's capacity
   * should be configured with virtual cores equal to its number of physical
   * cores. A container should be requested with the number of cores it can
   * saturate, i.e. the average number of threads it expects to have runnable
   * at a time.
   *
   * @return <em>num of virtual cpu cores</em> of the resource
   */
  @Public
  @Evolving
  public abstract int getVirtualCores();
  
  /**
   * Set <em>number of virtual cpu cores</em> of the resource.
   * 
   * Virtual cores are a unit for expressing CPU parallelism. A node's capacity
   * should be configured with virtual cores equal to its number of physical
   * cores. A container should be requested with the number of cores it can
   * saturate, i.e. the average number of threads it expects to have runnable
   * at a time.
   *
   * @param vCores <em>number of virtual cpu cores</em> of the resource
   */
  @Public
  @Evolving
  public abstract void setVirtualCores(int vCores);

  /**
   * Get ResourceInformation for all resources.
   *
   * @return Map of resource name to ResourceInformation
   */
  @Public
  @Evolving
  public abstract Map<String, ResourceInformation> getResources();

  /**
   * Get ResourceInformation for a specified resource.
   *
   * @param resource name of the resource
   * @return the ResourceInformation object for the resource
   * @throws YarnException if the resource can't be found
   */
  @Public
  @Evolving
  public abstract ResourceInformation getResourceInformation(String resource)
      throws YarnException;

  /**
   * Get the value for a specified resource. No information about the units is
   * returned.
   *
   * @param resource name of the resource
   * @return the value for the resource
   * @throws YarnException if the resource can't be found
   */
  @Public
  @Evolving
  public abstract Long getResourceValue(String resource) throws YarnException;

  /**
   * Set the ResourceInformation object for a particular resource.
   *
   * @param resource the resource for which the ResourceInformation is provided
   * @param resourceInformation ResourceInformation object
   * @throws ResourceNotFoundException if the resource is not found
   */
  @Public
  @Evolving
  public abstract void setResourceInformation(String resource,
      ResourceInformation resourceInformation) throws ResourceNotFoundException;

  /**
   * Set the value of a resource in the ResourceInformation object. The unit of
   * the value is assumed to be the one in the ResourceInformation object.
   *
   * @param resource the resource for which the value is provided.
   * @param value    the value to set
   * @throws ResourceNotFoundException if the resource is not found
   */
  @Public
  @Evolving
  public abstract void setResourceValue(String resource, Long value)
      throws ResourceNotFoundException;

  @Override
  public int hashCode() {
    final int prime = 263167;

    int result = (int) (939769357
        + getMemorySize()); // prime * result = 939769357 initially
    result = prime * result + getVirtualCores();
    for (Map.Entry<String, ResourceInformation> entry : getResources()
        .entrySet()) {
      if (entry.getKey().equals(ResourceInformation.MEMORY_MB.getName())
          || entry.getKey().equals(ResourceInformation.VCORES.getName())) {
        continue;
      }
      result = prime * result + entry.getValue().hashCode();
    }
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (!(obj instanceof Resource)) {
      return false;
    }
    Resource other = (Resource) obj;
    if (getMemorySize() != other.getMemorySize() || getVirtualCores() != other
        .getVirtualCores()) {
      return false;
    }
    return this.getResources().equals(other.getResources());
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("<memory:").append(getMemorySize()).append(", vCores:")
        .append(getVirtualCores());
    for (Map.Entry<String, ResourceInformation> entry : getResources()
        .entrySet()) {
      if (entry.getKey().equals(ResourceInformation.MEMORY_MB.getName())
          && entry.getValue().getUnits()
          .equals(ResourceInformation.MEMORY_MB.getUnits())) {
        continue;
      }
      if (entry.getKey().equals(ResourceInformation.VCORES.getName())
          && entry.getValue().getUnits()
          .equals(ResourceInformation.VCORES.getUnits())) {
        continue;
      }
      sb.append(", ").append(entry.getKey()).append(": ")
          .append(entry.getValue().getValue())
          .append(entry.getValue().getUnits());
    }
    sb.append(">");
    return sb.toString();
  }

  @Override
  public int compareTo(Resource other) {
    Map<String, ResourceInformation> thisResources, otherResources;
    thisResources = this.getResources();
    otherResources = other.getResources();
    long diff = thisResources.size() - otherResources.size();
    if (diff == 0) {
      // compare memory and vcores first(in that order) to preserve
      // existing behaviour
      if (thisResources.keySet().equals(otherResources.keySet())) {
        diff = this.getMemorySize() - other.getMemorySize();
        if (diff == 0) {
          diff = this.getVirtualCores() - other.getVirtualCores();
        }
        if (diff == 0) {
          for (Map.Entry<String, ResourceInformation> entry : thisResources
              .entrySet()) {
            if (entry.getKey().equals(ResourceInformation.MEMORY_MB.getName())
                || entry.getKey()
                .equals(ResourceInformation.VCORES.getName())) {
              continue;
            }
            diff =
                entry.getValue().compareTo(otherResources.get(entry.getKey()));
            if (diff != 0) {
              break;
            }
          }
        }
      }
    }
    return Long.compare(diff, 0);
  }
}