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.datastax.oss.driver.internal.core.util;
  
  public class NanoTime {
  
    private static final long ONE_HOUR = 3600L * 1000 * 1000 * 1000;
    private static final long ONE_MINUTE = 60L * 1000 * 1000 * 1000;
    private static final long ONE_SECOND = 1000 * 1000 * 1000;
    private static final long ONE_MILLISECOND = 1000 * 1000;
    private static final long ONE_MICROSECOND = 1000;
  
    /** Formats a duration in the best unit (truncating the fractional part). */
    public static String formatTimeSince(long startTimeNs) {
      return format(System.nanoTime() - startTimeNs);
    }
  
    /** Formats a duration in the best unit (truncating the fractional part). */
    public static String format(long elapsedNs) {
      if (elapsedNs >= ONE_HOUR) {
        long hours = elapsedNs / ONE_HOUR;
        long minutes = (elapsedNs % ONE_HOUR) / ONE_MINUTE;
        return hours + " h " + minutes + " mn";
      } else if (elapsedNs >= ONE_MINUTE) {
        long minutes = elapsedNs / ONE_MINUTE;
        long seconds = (elapsedNs % ONE_MINUTE) / ONE_SECOND;
        return minutes + " mn " + seconds + " s";
      } else if (elapsedNs >= ONE_SECOND) {
        long seconds = elapsedNs / ONE_SECOND;
        long milliseconds = (elapsedNs % ONE_SECOND) / ONE_MILLISECOND;
        return seconds + "." + milliseconds + " s";
      } else if (elapsedNs >= ONE_MILLISECOND) {
        return (elapsedNs / ONE_MILLISECOND) + " ms";
      } else if (elapsedNs >= ONE_MICROSECOND) {
        return (elapsedNs / ONE_MICROSECOND) + " us";
      } else {
        return elapsedNs + " ns";
      }
    }
  }
  