LogbackMDCAdapterTest.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.util;

import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertNotNull;
import static junit.framework.Assert.assertNull;
import static junit.framework.Assert.assertTrue;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CountDownLatch;

import org.junit.Test;
import ch.qos.logback.core.testUtil.RandomUtil;

public class LogbackMDCAdapterTest {

  final static String A_SUFFIX = "A_SUFFIX";
  final static String B_SUFFIX = "B_SUFFIX";

  int diff = RandomUtil.getPositiveInt();

  private final LogbackMDCAdapter mdcAdapter = new LogbackMDCAdapter();


  /**
   * Test that CopyOnInheritThreadLocal does not barf when the
   * MDC hashmap is null
   *
   * @throws InterruptedException
   */
  @Test
  public void lbclassic77Test() throws InterruptedException {
    Map<String, String> parentHM = getMapFromMDCAdapter(mdcAdapter);
    assertNull(parentHM);

    ChildThreadForMDCAdapter childThread = new ChildThreadForMDCAdapter(mdcAdapter);
    childThread.start();
    childThread.join();
    assertTrue(childThread.successul);
    assertNull(childThread.childHM);
  }

  @Test
  public void removeForNullKeyTest() {
    mdcAdapter.remove(null);
  }

  @Test
  public void removeInexistentKey() {
    mdcAdapter.remove("abcdlw0");
  }


  @Test
  public void sequenceWithGet() {
    mdcAdapter.put("k0", "v0");
    Map<String, String> map0 = mdcAdapter.copyOnInheritThreadLocal.get();
    mdcAdapter.get("k0");  // point 0
    mdcAdapter.put("k0", "v1");
    // verify that map0 is that in point 0
    assertEquals("v0", map0.get("k0"));
  }

  @Test
  public void sequenceWithGetPropertyMap() {
    mdcAdapter.put("k0", "v0");
    Map<String, String> map0 = mdcAdapter.getPropertyMap();  // point 0
    mdcAdapter.put("k0", "v1");
    // verify that map0 is that in point 0
    assertEquals("v0", map0.get("k0"));
  }

  // =================================================

  /**
   * Test that LogbackMDCAdapter copies its hashmap when a child
   * thread inherits it.
   *
   * @throws InterruptedException
   */
  @Test
  public void copyOnInheritenceTest() throws InterruptedException {
    CountDownLatch countDownLatch = new CountDownLatch(1);
    String firstKey = "x" + diff;
    String secondKey = "o" + diff;
    mdcAdapter.put(firstKey, firstKey + A_SUFFIX);

    ChildThread childThread = new ChildThread(mdcAdapter, firstKey, secondKey, countDownLatch);
    childThread.start();
    countDownLatch.await();
    mdcAdapter.put(firstKey, firstKey + B_SUFFIX);
    childThread.join();

    assertNull(mdcAdapter.get(secondKey));
    assertTrue(childThread.successful);

    Map<String, String> parentHM = getMapFromMDCAdapter(mdcAdapter);
    assertTrue(parentHM != childThread.childHM);

    HashMap<String, String> parentHMWitness = new HashMap<String, String>();
    parentHMWitness.put(firstKey, firstKey + B_SUFFIX);
    assertEquals(parentHMWitness, parentHM);

    HashMap<String, String> childHMWitness = new HashMap<String, String>();
    childHMWitness.put(firstKey, firstKey + A_SUFFIX);
    childHMWitness.put(secondKey, secondKey + A_SUFFIX);
    assertEquals(childHMWitness, childThread.childHM);

  }

  // see also http://jira.qos.ch/browse/LBCLASSIC-253
  @Test
  public void clearOnChildThreadShouldNotAffectParent() throws InterruptedException {
    String firstKey = "x" + diff;
    String secondKey = "o" + diff;

    mdcAdapter.put(firstKey, firstKey + A_SUFFIX);
    assertEquals(firstKey + A_SUFFIX, mdcAdapter.get(firstKey));

    Thread clearer = new ChildThread(mdcAdapter, firstKey, secondKey) {
      @Override
      public void run() {
        mdcAdapter.clear();
        assertNull(mdcAdapter.get(firstKey));
      }
    };

    clearer.start();
    clearer.join();

    assertEquals(firstKey + A_SUFFIX, mdcAdapter.get(firstKey));
  }

  // see http://jira.qos.ch/browse/LBCLASSIC-289
  // this test used to fail without synchronization code in LogbackMDCAdapter
  @Test
  public void nearSimultaneousPutsShouldNotCauseConcurrentModificationException() throws InterruptedException {
    // For the weirdest reason, modifications to mdcAdapter must be done
    // before the definition anonymous ChildThread class below. Otherwise, the
    // map in the child thread, the one contained in mdcAdapter.copyOnInheritThreadLocal,
    // is null. How strange is that?

    // let the map have lots of elements so that copying it takes time
     for (int i = 0; i < 2048; i++) {
      mdcAdapter.put("k" + i, "v" + i);
    }

    ChildThread childThread = new ChildThread(mdcAdapter, null, null) {
      @Override
      public void run() {
        for (int i = 0; i < 16; i++) {
          mdcAdapter.put("ck" + i, "cv" + i);
          Thread.yield();
        }
        successful = true;
      }
    };


    childThread.start();
    Thread.sleep(1);
    for (int i = 0; i < 16; i++) {
      mdcAdapter.put("K" + i, "V" + i);
    }
    childThread.join();
    assertTrue(childThread.successful);
  }


  Map<String, String> getMapFromMDCAdapter(LogbackMDCAdapter lma) {
    InheritableThreadLocal<Map<String, String>> copyOnInheritThreadLocal = lma.copyOnInheritThreadLocal;
    return copyOnInheritThreadLocal.get();
  }

  // ==========================    various thread classes
  class ChildThreadForMDCAdapter extends Thread {

    LogbackMDCAdapter logbackMDCAdapter;
    boolean successul;
    Map<String, String> childHM;

    ChildThreadForMDCAdapter(LogbackMDCAdapter logbackMDCAdapter) {
      this.logbackMDCAdapter = logbackMDCAdapter;
    }

    @Override
    public void run() {
      childHM = getMapFromMDCAdapter(logbackMDCAdapter);
      logbackMDCAdapter.get("");
      successul = true;
    }
  }


  class ChildThread extends Thread {

    LogbackMDCAdapter logbackMDCAdapter;
    String firstKey;
    String secondKey;
    boolean successful;
    Map<String, String> childHM;
    CountDownLatch countDownLatch;

    ChildThread(LogbackMDCAdapter logbackMDCAdapter) {
      this(logbackMDCAdapter, null, null);
    }

    ChildThread(LogbackMDCAdapter logbackMDCAdapter, String firstKey, String secondKey) {
      this(logbackMDCAdapter, firstKey, secondKey, null);
    }

    ChildThread(LogbackMDCAdapter logbackMDCAdapter, String firstKey, String secondKey, CountDownLatch countDownLatch) {
      super("chil");
      this.logbackMDCAdapter  = logbackMDCAdapter;
      this.firstKey = firstKey;
      this.secondKey = secondKey;
      this.countDownLatch = countDownLatch;
    }

    @Override
    public void run() {
      logbackMDCAdapter.put(secondKey, secondKey + A_SUFFIX);
      assertNotNull(logbackMDCAdapter.get(firstKey));
      assertEquals(firstKey + A_SUFFIX, logbackMDCAdapter.get(firstKey));
      if (countDownLatch != null) countDownLatch.countDown();
      assertEquals(secondKey + A_SUFFIX, logbackMDCAdapter.get(secondKey));
      successful = true;
      childHM = getMapFromMDCAdapter(logbackMDCAdapter);
    }
  }
}