content: /*
   * Copyright 2014-2025 Real Logic Limited.
   *
   * 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
   *
   * https://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.agrona.concurrent;
  
  import java.time.Instant;
  
  /**
   * Clock that provides the number of time units since the 1 Jan 1970 UTC.
   * <p>
   * This implementation may be replaced on some platforms for greater performance.
   * <p>
   * <b>Note:</b> The actual provided resolution may be a higher granularity than the possible precision.
   * For example, on Java 8 many JVMs will only advance a millisecond per tick so when requesting micros or nanos
   * then the returned time may be a multiple of milliseconds. Later JVMs tend to improve on this.
   */
  public final class HighResolutionClock
  {
      private HighResolutionClock()
      {
      }
  
      /**
       * The number of milliseconds since the 1 Jan 1970 UTC.
       *
       * @return the number of milliseconds since the 1 Jan 1970 UTC.
       */
      public static long epochMillis()
      {
          return System.currentTimeMillis();
      }
  
      /**
       * The number of microseconds since the 1 Jan 1970 UTC.
       *
       * @return the number of microseconds since the 1 Jan 1970 UTC.
       */
      public static long epochMicros()
      {
          final Instant now = Instant.now();
          final long seconds = now.getEpochSecond();
          final long nanosFromSecond = now.getNano();
  
          return (seconds * 1_000_000) + (nanosFromSecond / 1_000);
      }
  
      /**
       * The number of nanoseconds since the 1 Jan 1970 UTC.
       * <p>
       * Precision depends upon the JVM version used. Hotspot/OpenJDK 8 provides millisecond level precision, 11 provides
       * microsecond or lower granularity.
       *
       * @return the number of nanoseconds since the 1 Jan 1970 UTC.
       */
      public static long epochNanos()
      {
          final Instant now = Instant.now();
          final long seconds = now.getEpochSecond();
          final long nanosFromSecond = now.getNano();
  
          return (seconds * 1_000_000_000) + nanosFromSecond;
      }
  }
  