java-design-patterns/circuit-breaker/src/main/java/com/iluwatar/circuitbreaker/DelayedService.java

/*
 * The MIT License
 * Copyright © 2014-2019 Ilkka Seppälä
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.iluwatar.circuitbreaker;

/**
* This simulates the remote service
* It responds only after a certain timeout period (default set to 20 seconds)
*/
public class DelayedService {
  private final int delay;

  /**
   * Constructor to create an instance of DelayedService, which is down for first few seconds
   * @param delay the delay after which service would behave properly, in seconds
   */
  public DelayedService(int delay) {
    this.delay = delay;
  }

  public DelayedService() {
    this.delay = 60;
  }

  /**
   * @param serverStartTime Time at which actual server was started which makes calls to this service
   * @return The state of the service
   */
  public String response(long serverStartTime) {
    var currentTime = System.nanoTime();
    //Since currentTime and serverStartTime are both in nanoseconds, we convert it to
    //seconds by diving by 10e9 and ensure floating point division by multiplying it
    //with 1.0 first. We then check if it is greater or less than specified delay and then
    //send the reply
    if ((currentTime - serverStartTime) * 1.0 / (1000 * 1000 * 1000) < delay) {
      //Can use Thread.sleep() here to block and simulate a hung server
      return "Delayed service is down";
    } else {
      return "Delayed service is working";
    }
  }
}