/*
 * 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 org.apache.beam.sdk.util;

/**
 * Sleeper interface to use for requesting the current thread to sleep as specified in
 * {@link Thread#sleep(long)}.
 *
 * <p>
 * The default implementation can be accessed at {@link #DEFAULT}. Primarily used for testing.
 * </p>
 *
 * <p><b>Note</b>: This interface is copied from Google API client library to avoid its dependency.
 */
public interface Sleeper {

  /**
   * Causes the currently executing thread to sleep (temporarily cease execution) for the specified
   * number of milliseconds as specified in {@link Thread#sleep(long)}.
   *
   * @param millis length of time to sleep in milliseconds
   * @throws InterruptedException if any thread has interrupted the current thread
   */
  void sleep(long millis) throws InterruptedException;

  /** Provides the default implementation based on {@link Thread#sleep(long)}. */
  Sleeper DEFAULT = Thread::sleep;
}
