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.connection;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.mockito.Mockito.when;
  
  import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
  import com.datastax.oss.driver.api.core.config.DriverConfig;
  import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
  import com.datastax.oss.driver.api.core.connection.ReconnectionPolicy;
  import com.datastax.oss.driver.api.core.context.DriverContext;
  import java.time.Duration;
  import java.time.temporal.ChronoUnit;
  import org.junit.Before;
  import org.junit.Test;
  import org.mockito.Mock;
  import org.mockito.MockitoAnnotations;
  
  public class ExponentialReconnectionPolicyTest {
  
    @Mock private DriverContext driverContext;
    @Mock private DriverConfig driverConfig;
    @Mock private DriverExecutionProfile profile;
    private final long baseDelay = 1000L;
    private final long maxDelay = 60000L;
  
    @Before
    public void setup() {
      MockitoAnnotations.initMocks(this);
      when(driverConfig.getDefaultProfile()).thenReturn(profile);
      when(driverContext.getConfig()).thenReturn(driverConfig);
      when(profile.getDuration(DefaultDriverOption.RECONNECTION_BASE_DELAY))
          .thenReturn(Duration.of(baseDelay, ChronoUnit.MILLIS));
      when(profile.getDuration(DefaultDriverOption.RECONNECTION_MAX_DELAY))
          .thenReturn(Duration.of(maxDelay, ChronoUnit.MILLIS));
    }
  
    @Test
    public void should_generate_exponential_delay_with_jitter() throws Exception {
      ExponentialReconnectionPolicy policy = new ExponentialReconnectionPolicy(driverContext);
      ReconnectionPolicy.ReconnectionSchedule schedule = policy.newControlConnectionSchedule(false);
      // generate a number of delays and make sure they are all within the base/max values range
      // limit the loop to 53 as the bit shift and min/max calculations will cause long overflows
      // past that
      for (int i = 0; i < 54; ++i) {
        // compute the min and max delays based on attempt count (i) and prevent long overflows
        long exponentialDelay = Math.min(baseDelay * (1L << i), maxDelay);
        // min will be 85% of the pure exponential delay (with a floor of baseDelay)
        long minJitterDelay = Math.max(baseDelay, (exponentialDelay * 85) / 100);
        // max will be 115% of the pure exponential delay (with a ceiling of maxDelay)
        long maxJitterDelay = Math.min(maxDelay, (exponentialDelay * 115) / 100);
        long delay = schedule.nextDelay().toMillis();
        assertThat(delay).isBetween(minJitterDelay, maxJitterDelay);
      }
    }
  }
  