src/main/java/com/google/devtools/build/lib/actions/ResourceSet.java

// Copyright 2014 Google Inc. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.actions;

import com.google.common.base.Splitter;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.common.options.Converter;
import com.google.devtools.common.options.OptionsParsingException;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Instances of this class represent an estimate of the resource consumption
 * for a particular Action, or the total available resources.  We plan to
 * use this to do smarter scheduling of actions, for example making sure
 * that we don't schedule jobs concurrently if they would use so much
 * memory as to cause the machine to thrash.
 */
@Immutable
public class ResourceSet {

  /** For actions that consume negligible resources. */
  public static final ResourceSet ZERO = new ResourceSet(0.0, 0.0, 0.0);

  /** The amount of real memory (resident set size). */
  private final double memoryMb;

  /** The number of CPUs, or fractions thereof. */
  private final double cpuUsage;

  /**
   * Relative amount of used I/O resources (with 1.0 being total available amount on an "average"
   * workstation.
   */
  private final double ioUsage;
  
  public ResourceSet(double memoryMb, double cpuUsage, double ioUsage) {
    this.memoryMb = memoryMb;
    this.cpuUsage = cpuUsage;
    this.ioUsage = ioUsage;
  }

  /** Returns the amount of real memory (resident set size) used in MB. */
  public double getMemoryMb() {
    return memoryMb;
  }

  /**
   * Returns the number of CPUs (or fractions thereof) used.
   * For a CPU-bound single-threaded process, this will be 1.0.
   * For a single-threaded process which spends part of its
   * time waiting for I/O, this will be somewhere between 0.0 and 1.0.
   * For a multi-threaded or multi-process application,
   * this may be more than 1.0.
   */
  public double getCpuUsage() {
    return cpuUsage;
  }

  /**
   * Returns the amount of I/O used.
   * Full amount of available I/O resources on the "average" workstation is
   * considered to be 1.0.
   */
  public double getIoUsage() {
    return ioUsage;
  }

  public static class ResourceSetConverter implements Converter<ResourceSet> {
    private static final Splitter SPLITTER = Splitter.on(',');

    @Override
    public ResourceSet convert(String input) throws OptionsParsingException {
      Iterator<String> values = SPLITTER.split(input).iterator();
      try {
        double memoryMb = Double.parseDouble(values.next());
        double cpuUsage = Double.parseDouble(values.next());
        double ioUsage = Double.parseDouble(values.next());
        if (values.hasNext()) {
          throw new OptionsParsingException("Expected exactly 3 comma-separated float values");
        }
        if (memoryMb <= 0.0 || cpuUsage <= 0.0 || ioUsage <= 0.0) {
          throw new OptionsParsingException("All resource values must be positive");
        }
        return new ResourceSet(memoryMb, cpuUsage, ioUsage);
      } catch (NumberFormatException nfe) {
        throw new OptionsParsingException("Expected exactly 3 comma-separated float values", nfe);
      } catch (NoSuchElementException nsee) {
        throw new OptionsParsingException("Expected exactly 3 comma-separated float values", nsee);
      }
    }

    @Override
    public String getTypeDescription() {
      return "comma-separated available amount of RAM (in MB), CPU (in cores) and "
          + "available I/O (1.0 being average workstation)";
    }

  }
}