/**
 * 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.hadoop.ipc;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.doThrow;
import static org.mockito.Mockito.reset;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.ipc.CallQueueManager.CallQueueOverflowException;
import org.apache.hadoop.security.UserGroupInformation;
import org.junit.Test;
import org.mockito.Mockito;

public class TestCallQueueManager {
  private CallQueueManager<FakeCall> manager;
  private Configuration conf = new Configuration();

  public class FakeCall implements Schedulable {
    public final int tag; // Can be used for unique identification
    private int priorityLevel;
    UserGroupInformation fakeUgi = UserGroupInformation.createRemoteUser
        ("fakeUser");
    public FakeCall(int tag) {
      this.tag = tag;
    }

    @Override
    public UserGroupInformation getUserGroupInformation() {
      return fakeUgi;
    }

    @Override
    public int getPriorityLevel() {
      return priorityLevel;
    }

    public void setPriorityLevel(int level) {
      this.priorityLevel = level;
    }
  }

  /**
   * Putter produces FakeCalls
   */
  public class Putter implements Runnable {
    private final CallQueueManager<FakeCall> cq;

    public final int tag;
    public volatile int callsAdded = 0; // How many calls we added, accurate unless interrupted
    private final int maxCalls;

    private volatile boolean isRunning = true;

    public Putter(CallQueueManager<FakeCall> aCq, int maxCalls, int tag) {
      this.maxCalls = maxCalls;
      this.cq = aCq;
      this.tag = tag;
    }

    public void run() {
      try {
        // Fill up to max (which is infinite if maxCalls < 0)
        while (isRunning && (callsAdded < maxCalls || maxCalls < 0)) {
          FakeCall call = new FakeCall(this.tag);
          call.setPriorityLevel(cq.getPriorityLevel(call));
          cq.put(call);
          callsAdded++;
        }
      } catch (InterruptedException e) {
        return;
      }
    }

    public void stop() {
      this.isRunning = false;
    }
  }

  /**
   * Taker consumes FakeCalls
   */
  public class Taker implements Runnable {
    private final CallQueueManager<FakeCall> cq;

    public final int tag; // if >= 0 means we will only take the matching tag, and put back
                          // anything else
    public volatile int callsTaken = 0; // total calls taken, accurate if we aren't interrupted
    public volatile FakeCall lastResult = null; // the last thing we took
    private final int maxCalls; // maximum calls to take

    public Taker(CallQueueManager<FakeCall> aCq, int maxCalls, int tag) {
      this.maxCalls = maxCalls;
      this.cq = aCq;
      this.tag = tag;
    }

    public void run() {
      try {
        // Take while we don't exceed maxCalls, or if maxCalls is undefined (< 0)
        while (callsTaken < maxCalls || maxCalls < 0) {
          FakeCall res = cq.take();

          if (tag >= 0 && res.tag != this.tag) {
            // This call does not match our tag, we should put it back and try again
            cq.put(res);
          } else {
            callsTaken++;
            lastResult = res;
          }
        }
      } catch (InterruptedException e) {
        return;
      }
    }
  }

  // Assert we can take exactly the numberOfTakes
  public void assertCanTake(CallQueueManager<FakeCall> cq, int numberOfTakes,
    int takeAttempts) throws InterruptedException {

    Taker taker = new Taker(cq, takeAttempts, -1);
    Thread t = new Thread(taker);
    t.start();
    t.join(100);

    assertEquals(taker.callsTaken, numberOfTakes);
    t.interrupt();
  }

  // Assert we can put exactly the numberOfPuts
  public void assertCanPut(CallQueueManager<FakeCall> cq, int numberOfPuts,
    int putAttempts) throws InterruptedException {

    Putter putter = new Putter(cq, putAttempts, -1);
    Thread t = new Thread(putter);
    t.start();
    t.join(100);

    assertEquals(numberOfPuts, putter.callsAdded);
    t.interrupt();
  }


  private static final Class<? extends BlockingQueue<FakeCall>> queueClass
      = CallQueueManager.convertQueueClass(LinkedBlockingQueue.class, FakeCall.class);

  private static final Class<? extends RpcScheduler> schedulerClass
      = CallQueueManager.convertSchedulerClass(DefaultRpcScheduler.class);

  @Test
  public void testCallQueueCapacity() throws InterruptedException {
    manager = new CallQueueManager<FakeCall>(queueClass, schedulerClass, false,
        10, "", conf);

    assertCanPut(manager, 10, 20); // Will stop at 10 due to capacity
  }

  @Test
  public void testEmptyConsume() throws InterruptedException {
    manager = new CallQueueManager<FakeCall>(queueClass, schedulerClass, false,
        10, "", conf);

    assertCanTake(manager, 0, 1); // Fails since it's empty
  }

  static Class<? extends BlockingQueue<FakeCall>> getQueueClass(
      String prefix, Configuration conf) {
    String name = prefix + "." + CommonConfigurationKeys.IPC_CALLQUEUE_IMPL_KEY;
    Class<?> queueClass = conf.getClass(name, LinkedBlockingQueue.class);
    return CallQueueManager.convertQueueClass(queueClass, FakeCall.class);
  }

  @Test
  public void testFcqBackwardCompatibility() throws InterruptedException {
    // Test BackwardCompatibility to ensure existing FCQ deployment still
    // work without explicitly specifying DecayRpcScheduler
    Configuration conf = new Configuration();
    final String ns = CommonConfigurationKeys.IPC_NAMESPACE + ".0";

    final String queueClassName = "org.apache.hadoop.ipc.FairCallQueue";
    conf.setStrings(ns + "." + CommonConfigurationKeys.IPC_CALLQUEUE_IMPL_KEY,
        queueClassName);

    // Specify only Fair Call Queue without a scheduler
    // Ensure the DecayScheduler will be added to avoid breaking.
    Class<? extends RpcScheduler> scheduler = Server.getSchedulerClass(ns,
        conf);
    assertTrue(scheduler.getCanonicalName().
        equals("org.apache.hadoop.ipc.DecayRpcScheduler"));

    Class<? extends BlockingQueue<FakeCall>> queue =
        (Class<? extends BlockingQueue<FakeCall>>) getQueueClass(ns, conf);
    assertTrue(queue.getCanonicalName().equals(queueClassName));

    manager = new CallQueueManager<FakeCall>(queue, scheduler, false,
        8, "", conf);

    // Default FCQ has 4 levels and the max capacity is 8
    assertCanPut(manager, 3, 3);
  }

  @Test
  public void testSchedulerWithoutFCQ() throws InterruptedException {
    Configuration conf = new Configuration();
    // Test DecayedRpcScheduler without FCQ
    // Ensure the default LinkedBlockingQueue can work with DecayedRpcScheduler
    final String ns = CommonConfigurationKeys.IPC_NAMESPACE + ".0";
    final String schedulerClassName = "org.apache.hadoop.ipc.DecayRpcScheduler";
    conf.setStrings(ns + "." + CommonConfigurationKeys.IPC_SCHEDULER_IMPL_KEY,
        schedulerClassName);

    Class<? extends BlockingQueue<FakeCall>> queue =
        (Class<? extends BlockingQueue<FakeCall>>) getQueueClass(ns, conf);
    assertTrue(queue.getCanonicalName().equals("java.util.concurrent." +
        "LinkedBlockingQueue"));

    manager = new CallQueueManager<FakeCall>(queue,
        Server.getSchedulerClass(ns, conf), false,
        3, "", conf);

    // LinkedBlockingQueue with a capacity of 3 can put 3 calls
    assertCanPut(manager, 3, 3);
    // LinkedBlockingQueue with a capacity of 3 can't put 1 more call
    assertCanPut(manager, 0, 1);
  }

  @Test(timeout=60000)
  public void testSwapUnderContention() throws InterruptedException {
    manager = new CallQueueManager<FakeCall>(queueClass, schedulerClass, false,
        5000, "", conf);

    ArrayList<Putter> producers = new ArrayList<Putter>();
    ArrayList<Taker> consumers = new ArrayList<Taker>();

    HashMap<Runnable, Thread> threads = new HashMap<Runnable, Thread>();

    // Create putters and takers
    for (int i=0; i < 1000; i++) {
      Putter p = new Putter(manager, -1, -1);
      Thread pt = new Thread(p);
      producers.add(p);
      threads.put(p, pt);

      pt.start();
    }

    for (int i=0; i < 100; i++) {
      Taker t = new Taker(manager, -1, -1);
      Thread tt = new Thread(t);
      consumers.add(t);
      threads.put(t, tt);

      tt.start();
    }

    Thread.sleep(500);

    for (int i=0; i < 5; i++) {
      manager.swapQueue(schedulerClass, queueClass, 5000, "", conf);
    }

    // Stop the producers
    for (Putter p : producers) {
      p.stop();
    }

    // Wait for consumers to wake up, then consume
    Thread.sleep(2000);
    assertEquals(0, manager.size());

    // Ensure no calls were dropped
    long totalCallsCreated = 0;
    for (Putter p : producers) {
      threads.get(p).interrupt();
    }
    for (Putter p : producers) {
      threads.get(p).join();
      totalCallsCreated += p.callsAdded;
    }
    
    long totalCallsConsumed = 0;
    for (Taker t : consumers) {
      threads.get(t).interrupt();
    }
    for (Taker t : consumers) {
      threads.get(t).join();
      totalCallsConsumed += t.callsTaken;
    }

    assertEquals(totalCallsConsumed, totalCallsCreated);
  }

  public static class ExceptionFakeCall implements Schedulable {
    public ExceptionFakeCall() {
      throw new IllegalArgumentException("Exception caused by call queue " +
          "constructor.!!");
    }

    @Override
    public UserGroupInformation getUserGroupInformation() {
      return null;
    }

    @Override
    public int getPriorityLevel() {
      return 0;
    }
  }

  public static class ExceptionFakeScheduler {
    public ExceptionFakeScheduler() {
      throw new IllegalArgumentException("Exception caused by " +
          "scheduler constructor.!!");
    }
  }

  private static final Class<? extends RpcScheduler>
      exceptionSchedulerClass = CallQueueManager.convertSchedulerClass(
      ExceptionFakeScheduler.class);

  private static final Class<? extends BlockingQueue<ExceptionFakeCall>>
      exceptionQueueClass = CallQueueManager.convertQueueClass(
      ExceptionFakeCall.class, ExceptionFakeCall.class);

  @Test
  public void testCallQueueConstructorException() throws InterruptedException {
    try {
      new CallQueueManager<ExceptionFakeCall>(exceptionQueueClass,
          schedulerClass, false, 10, "", new Configuration());
      fail();
    } catch (RuntimeException re) {
      assertTrue(re.getCause() instanceof IllegalArgumentException);
      assertEquals("Exception caused by call queue constructor.!!", re
          .getCause()
          .getMessage());
    }
  }

  @Test
  public void testSchedulerConstructorException() throws InterruptedException {
    try {
      new CallQueueManager<FakeCall>(queueClass, exceptionSchedulerClass,
          false, 10, "", new Configuration());
      fail();
    } catch (RuntimeException re) {
      assertTrue(re.getCause() instanceof IllegalArgumentException);
      assertEquals("Exception caused by scheduler constructor.!!", re.getCause()
          .getMessage());
    }
  }

  @SuppressWarnings("unchecked")
  @Test
  public void testCallQueueOverflowExceptions() throws Exception {
    RpcScheduler scheduler = Mockito.mock(RpcScheduler.class);
    BlockingQueue<Schedulable> queue = Mockito.mock(BlockingQueue.class);
    CallQueueManager<Schedulable> cqm =
        Mockito.spy(new CallQueueManager<>(queue, scheduler, false));
    Schedulable call = new FakeCall(0);

    // call queue exceptions passed threw as-is
    doThrow(CallQueueOverflowException.KEEPALIVE).when(queue).add(call);
    try {
      cqm.add(call);
      fail("didn't throw");
    } catch (CallQueueOverflowException cqe) {
      assertSame(CallQueueOverflowException.KEEPALIVE, cqe);
    }

    // standard exception for blocking queue full converted to overflow
    // exception.
    doThrow(new IllegalStateException()).when(queue).add(call);
    try {
      cqm.add(call);
      fail("didn't throw");
    } catch (Exception ex) {
      assertTrue(ex.toString(), ex instanceof CallQueueOverflowException);
    }

    // backoff disabled, put is put to queue.
    reset(queue);
    cqm.setClientBackoffEnabled(false);
    cqm.put(call);
    verify(queue, times(1)).put(call);
    verify(queue, times(0)).add(call);

    // backoff enabled, put is add to queue.
    reset(queue);
    cqm.setClientBackoffEnabled(true);
    doReturn(Boolean.FALSE).when(cqm).shouldBackOff(call);
    cqm.put(call);
    verify(queue, times(0)).put(call);
    verify(queue, times(1)).add(call);
    reset(queue);

    // backoff is enabled, put + scheduler backoff = overflow exception.
    reset(queue);
    cqm.setClientBackoffEnabled(true);
    doReturn(Boolean.TRUE).when(cqm).shouldBackOff(call);
    try {
      cqm.put(call);
      fail("didn't fail");
    } catch (Exception ex) {
      assertTrue(ex.toString(), ex instanceof CallQueueOverflowException);
    }
    verify(queue, times(0)).put(call);
    verify(queue, times(0)).add(call);
  }
}