content: /*
   * 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 com.alibaba.metrics.os.linux;
  
  import com.alibaba.metrics.CachedMetricSet;
  import com.alibaba.metrics.Metric;
  import com.alibaba.metrics.MetricName;
  import com.alibaba.metrics.PersistentGauge;
  import com.alibaba.metrics.os.utils.FileUtils;
  import com.alibaba.metrics.os.utils.FormatUtils;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.TimeUnit;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  public class SystemLoadGaugeSet extends CachedMetricSet {
  
      private static final String DEFAULT_FILE_PATH = "/proc/loadavg";
  
      // Pattern.DOTALL to match pattern across multiple lines
      private static final Pattern loadPattern =
              Pattern.compile("^([\\d\\.]+)\\s+([\\d\\.]+)\\s+([\\d\\.]+)\\s+[\\d]+/[\\d]+\\s+([\\d]+).*$",
                      Pattern.DOTALL);
  
      private enum LoadAvg {
          ONE_MIN, FIVE_MIN, FIFTEEN_MIN
      }
  
      // store the system load average, in the order of 1min, 5min, 15min
      private float[] loadAvg;
  
      private String filePath;
  
      public SystemLoadGaugeSet() {
          this(DEFAULT_DATA_TTL, TimeUnit.MILLISECONDS, DEFAULT_FILE_PATH);
      }
  
      public SystemLoadGaugeSet(long dataTTL, TimeUnit unit) {
          this(dataTTL, unit, DEFAULT_FILE_PATH);
      }
  
      public SystemLoadGaugeSet(long dataTTL, TimeUnit unit, String filePath) {
          super(dataTTL, unit);
          loadAvg = new float[LoadAvg.values().length];
          this.filePath = filePath;
      }
  
      @Override
      public Map<MetricName, Metric> getMetrics() {
          final Map<MetricName, Metric> gauges = new HashMap<MetricName, Metric>();
  
          gauges.put(MetricName.build("load.1min"), new PersistentGauge<Float>() {
              @Override
              public Float getValue() {
                  refreshIfNecessary();
                  return loadAvg[LoadAvg.ONE_MIN.ordinal()];
              }
          });
  
          gauges.put(MetricName.build("load.5min"), new PersistentGauge<Float>() {
              @Override
              public Float getValue() {
                  refreshIfNecessary();
                  return loadAvg[LoadAvg.FIVE_MIN.ordinal()];
              }
          });
  
          gauges.put(MetricName.build("load.15min"), new PersistentGauge<Float>() {
              @Override
              public Float getValue() {
                  refreshIfNecessary();
                  return loadAvg[LoadAvg.FIFTEEN_MIN.ordinal()];
              }
          });
  
          return gauges;
      }
  
  
      @Override
      protected void getValueInternal() {
          String loadResult = FileUtils.readFile(filePath);
          Matcher loadMatcher = loadPattern.matcher(loadResult);
  
          if (loadMatcher.matches()) {
              loadAvg[LoadAvg.ONE_MIN.ordinal()] = FormatUtils.formatFloat(loadMatcher.group(1));
              loadAvg[LoadAvg.FIVE_MIN.ordinal()] = FormatUtils.formatFloat(loadMatcher.group(2));
              loadAvg[LoadAvg.FIFTEEN_MIN.ordinal()] = FormatUtils.formatFloat(loadMatcher.group(3));
          }
      }
  }
  