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.util.concurrent;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.mockito.Mockito.times;
  import static org.mockito.Mockito.verify;
  import static org.mockito.Mockito.verifyNoMoreInteractions;
  import static org.mockito.Mockito.when;
  
  import com.datastax.oss.driver.TestDataProviders;
  import com.datastax.oss.driver.api.core.connection.ReconnectionPolicy.ReconnectionSchedule;
  import com.tngtech.java.junit.dataprovider.DataProviderRunner;
  import com.tngtech.java.junit.dataprovider.UseDataProvider;
  import io.netty.channel.embedded.EmbeddedChannel;
  import io.netty.util.concurrent.EventExecutor;
  import java.time.Duration;
  import java.util.concurrent.Callable;
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.CompletionStage;
  import java.util.concurrent.atomic.AtomicInteger;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.mockito.Mock;
  import org.mockito.MockitoAnnotations;
  
  @RunWith(DataProviderRunner.class)
  public class ReconnectionTest {
  
    @Mock private ReconnectionSchedule reconnectionSchedule;
    @Mock private Runnable onStartCallback;
    @Mock private Runnable onStopCallback;
    private EmbeddedChannel channel;
  
    private MockReconnectionTask reconnectionTask;
    private Reconnection reconnection;
  
    @Before
    public void setup() {
      MockitoAnnotations.initMocks(this);
  
      // Unfortunately Netty does not expose EmbeddedEventLoop, so we have to go through a channel
      channel = new EmbeddedChannel();
      EventExecutor eventExecutor = channel.eventLoop();
  
      reconnectionTask = new MockReconnectionTask();
      reconnection =
          new Reconnection(
              "test",
              eventExecutor,
              () -> reconnectionSchedule,
              reconnectionTask,
              onStartCallback,
              onStopCallback);
    }
  
    @Test
    public void should_start_out_not_running() {
      assertThat(reconnection.isRunning()).isFalse();
    }
  
    @Test
    public void should_schedule_first_attempt_on_start() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofSeconds(1));
  
      // When
      reconnection.start();
  
      // Then
      verify(reconnectionSchedule).nextDelay();
      assertThat(reconnection.isRunning()).isTrue();
      verify(onStartCallback).run();
    }
  
    @Test
    public void should_ignore_start_if_already_started() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofSeconds(1));
      reconnection.start();
      verify(reconnectionSchedule).nextDelay();
      verify(onStartCallback).run();
  
      // When
      reconnection.start();
  
      // Then
      verifyNoMoreInteractions(reconnectionSchedule, onStartCallback);
    }
  
    @Test
    public void should_stop_if_first_attempt_succeeds() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofNanos(1));
      reconnection.start();
      verify(reconnectionSchedule).nextDelay();
  
      // When
      // the reconnection task is scheduled:
      runPendingTasks();
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // the reconnection task completes:
      reconnectionTask.complete(true);
      runPendingTasks();
  
      // Then
      assertThat(reconnection.isRunning()).isFalse();
      verify(onStopCallback).run();
    }
  
    @Test
    public void should_reschedule_if_first_attempt_fails() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofNanos(1));
      reconnection.start();
      verify(reconnectionSchedule).nextDelay();
  
      // When
      // the reconnection task is scheduled:
      runPendingTasks();
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // the reconnection task completes:
      reconnectionTask.complete(false);
      runPendingTasks();
  
      // Then
      // schedule was called again
      verify(reconnectionSchedule, times(2)).nextDelay();
      runPendingTasks();
      // task was called again
      assertThat(reconnectionTask.callCount()).isEqualTo(2);
      // still running
      assertThat(reconnection.isRunning()).isTrue();
  
      // When
      // second attempt completes
      reconnectionTask.complete(true);
      runPendingTasks();
  
      // Then
      assertThat(reconnection.isRunning()).isFalse();
      verify(onStopCallback).run();
    }
  
    @Test
    public void should_reconnect_now_if_next_attempt_not_started() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofDays(1));
      reconnection.start();
      verify(reconnectionSchedule).nextDelay();
  
      // When
      reconnection.reconnectNow(false);
      runPendingTasks();
  
      // Then
      // reconnection task was run immediately
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // if that attempt fails, another reconnection should be scheduled
      reconnectionTask.complete(false);
      runPendingTasks();
      verify(reconnectionSchedule, times(2)).nextDelay();
    }
  
    @Test
    public void should_reconnect_now_if_stopped_and_forced() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofDays(1));
      assertThat(reconnection.isRunning()).isFalse();
  
      // When
      reconnection.reconnectNow(true);
      runPendingTasks();
  
      // Then
      // reconnection task was run immediately
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // if that attempt failed, another reconnection was scheduled
      reconnectionTask.complete(false);
      runPendingTasks();
      verify(reconnectionSchedule).nextDelay();
    }
  
    @Test
    @UseDataProvider(location = TestDataProviders.class, value = "booleans")
    public void should_reconnect_now_when_attempt_in_progress(boolean force) {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofNanos(1));
      reconnection.start();
      runPendingTasks();
      // the next scheduled attempt has started, but not completed yet
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
  
      // When
      reconnection.reconnectNow(force);
      runPendingTasks();
  
      // Then
      // reconnection task should not have been called again
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // should still run until current attempt completes
      assertThat(reconnection.isRunning()).isTrue();
      reconnectionTask.complete(true);
      runPendingTasks();
      assertThat(reconnection.isRunning()).isFalse();
    }
  
    @Test
    public void should_not_reconnect_now_if_stopped_and_not_forced() {
      // Given
      assertThat(reconnection.isRunning()).isFalse();
  
      // When
      reconnection.reconnectNow(false);
      runPendingTasks();
  
      // Then
      assertThat(reconnectionTask.callCount()).isEqualTo(0);
    }
  
    @Test
    public void should_stop_between_attempts() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofSeconds(10));
      reconnection.start();
      runPendingTasks();
      verify(reconnectionSchedule).nextDelay();
  
      // When
      reconnection.stop();
      runPendingTasks();
  
      // Then
      verify(onStopCallback).run();
      assertThat(reconnection.isRunning()).isFalse();
    }
  
    @Test
    public void should_restart_after_stopped_between_attempts() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofSeconds(10));
      reconnection.start();
      runPendingTasks();
      verify(reconnectionSchedule).nextDelay();
      reconnection.stop();
      runPendingTasks();
      assertThat(reconnection.isRunning()).isFalse();
  
      // When
      reconnection.start();
      runPendingTasks();
  
      // Then
      verify(reconnectionSchedule, times(2)).nextDelay();
      assertThat(reconnection.isRunning()).isTrue();
    }
  
    @Test
    @UseDataProvider(location = TestDataProviders.class, value = "booleans")
    public void should_stop_while_attempt_in_progress(boolean outcome) {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofNanos(1));
      reconnection.start();
      runPendingTasks();
      // the next scheduled attempt has started, but not completed yet
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      verify(onStartCallback).run();
  
      // When
      reconnection.stop();
      runPendingTasks();
  
      // Then
      // should let the current attempt complete (whatever its outcome), and become stopped only then
      assertThat(reconnection.isRunning()).isTrue();
      verifyNoMoreInteractions(onStopCallback);
      reconnectionTask.complete(outcome);
      runPendingTasks();
      verify(onStopCallback).run();
      assertThat(reconnection.isRunning()).isFalse();
    }
  
    @Test
    public void should_restart_after_stopped_while_attempt_in_progress() {
      // Given
      when(reconnectionSchedule.nextDelay()).thenReturn(Duration.ofNanos(1));
      reconnection.start();
      runPendingTasks();
      // the next scheduled attempt has started, but not completed yet
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      verify(onStartCallback).run();
      // now stop
      reconnection.stop();
      runPendingTasks();
      assertThat(reconnection.isRunning()).isTrue();
  
      // When
      reconnection.start();
      runPendingTasks();
  
      // Then
      assertThat(reconnection.isRunning()).isTrue();
      // still waiting on the same attempt, should not have called the task again
      assertThat(reconnectionTask.callCount()).isEqualTo(1);
      // because we were still in progress all the time, to the outside it's as if the stop/restart
      // had never happened
      verifyNoMoreInteractions(onStartCallback);
      verifyNoMoreInteractions(onStopCallback);
  
      // When
      reconnectionTask.complete(true);
      runPendingTasks();
  
      // Then
      assertThat(reconnection.isRunning()).isFalse();
      verify(onStopCallback).run();
    }
  
    private void runPendingTasks() {
      channel.runPendingTasks();
    }
  
    private static class MockReconnectionTask implements Callable<CompletionStage<Boolean>> {
      private volatile CompletableFuture<Boolean> nextResult;
      private final AtomicInteger callCount = new AtomicInteger();
  
      @Override
      public CompletionStage<Boolean> call() throws Exception {
        assertThat(nextResult == null || nextResult.isDone()).isTrue();
        callCount.incrementAndGet();
        nextResult = new CompletableFuture<>();
        return nextResult;
      }
  
      private void complete(boolean outcome) {
        assertThat(nextResult != null || !nextResult.isDone()).isTrue();
        nextResult.complete(outcome);
        nextResult = null;
      }
  
      private int callCount() {
        return callCount.get();
      }
    }
  }
  