/*
 * Copyright 2017, Google Inc.
 * 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.instrumentation.common;

/**
 * Interface for getting the current time.
 */
public abstract class Clock {

  /**
   * Obtains the current instant from this clock.
   *
   * @return the current instant.
   */
  public abstract Timestamp now();

  /**
   * Returns a time measurement with nanosecond precision that can only be used to calculate elapsed
   * time.
   *
   * @return a time measurement with nanosecond precision that can only be used to calculate elapsed
   *     time.
   */
  public abstract long nowNanos();
}

Add an interface for getting the time throughout the Instrumentation library.
Add an interface for getting the time throughout the Instrumentation library.

Clock is an abstract class. It can have different implementations for Java 7,
Java 8, and tests.
