content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.druid.util;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicLongArray;
  
  public class Histogram {
      private final long[] ranges;
      private final AtomicLongArray rangeCounters;
  
      public Histogram(long... ranges) {
          this.ranges = ranges;
          this.rangeCounters = new AtomicLongArray(ranges.length + 1);
      }
  
      public static Histogram makeHistogram(int rangeCount) {
          long[] rangeValues = new long[rangeCount];
  
          for (int i = 0; i < rangeValues.length; ++i) {
              rangeValues[i] = (long) Math.pow(10, i);
          }
  
          return new Histogram(rangeValues);
      }
  
      public Histogram(TimeUnit timeUnit, long... ranges) {
          this.ranges = new long[ranges.length];
          for (int i = 0; i < ranges.length; i++) {
              this.ranges[i] = TimeUnit.MILLISECONDS.convert(ranges[i], timeUnit);
          }
  
          rangeCounters = new AtomicLongArray(ranges.length + 1);
      }
  
      public void reset() {
          for (int i = 0; i < rangeCounters.length(); i++) {
              rangeCounters.set(i, 0);
          }
      }
  
      public void record(long millis) {
          int index = rangeCounters.length() - 1;
          for (int i = 0; i < ranges.length; ++i) {
              if (millis < ranges[i]) {
                  index = i;
                  break;
              }
          }
  
          rangeCounters.incrementAndGet(index);
      }
  
      public long get(int index) {
          return rangeCounters.get(index);
      }
  
      public long[] toArray() {
          long[] array = new long[rangeCounters.length()];
          for (int i = 0; i < rangeCounters.length(); i++) {
              array[i] = rangeCounters.get(i);
          }
          return array;
      }
  
      public long[] toArrayAndReset() {
          long[] array = new long[rangeCounters.length()];
          for (int i = 0; i < rangeCounters.length(); i++) {
              array[i] = rangeCounters.getAndSet(i, 0);
          }
  
          return array;
      }
  
      public long[] getRanges() {
          return ranges;
      }
  
      public long getValue(int index) {
          return rangeCounters.get(index);
      }
  
      public long getSum() {
          long sum = 0;
          for (int i = 0; i < rangeCounters.length(); ++i) {
              sum += rangeCounters.get(i);
          }
          return sum;
      }
  
      public String toString() {
          StringBuilder buf = new StringBuilder();
          buf.append('[');
          for (int i = 0; i < rangeCounters.length(); ++i) {
              if (i != 0) {
                  buf.append(',');
              }
              buf.append(rangeCounters.get(i));
          }
          buf.append(']');
          return buf.toString();
      }
  }
  