package org.apache.log4j;

import junit.framework.TestCase;

import java.lang.ref.Reference;

import java.lang.reflect.Field;

/**

 * Test for MDC

 * 

 *  @author Maarten Bosteels

 */

public class MDCTestCase extends TestCase {

  public void setUp() {

    MDC.clear();

  }

  public void tearDown() {

    MDC.clear();

  }

  public void testPut() throws Exception {

    MDC.put("key", "some value");

    assertEquals("some value", MDC.get("key"));

    assertEquals(1, MDC.getContext().size());

  }

  public void testRemoveLastKey() throws Exception {

    MDC.put("key", "some value");

    MDC.remove("key");

    checkThreadLocalsForLeaks();

  }

  private void checkThreadLocalsForLeaks() throws Exception {

      // this code is heavily based on code in org.apache.catalina.loader.WebappClassLoader

      // Make the fields in the Thread class that store ThreadLocals accessible    

      Field threadLocalsField = Thread.class.getDeclaredField("threadLocals");

      threadLocalsField.setAccessible(true);

      Field inheritableThreadLocalsField = Thread.class.getDeclaredField("inheritableThreadLocals");

      inheritableThreadLocalsField.setAccessible(true);

      // Make the underlying array of ThreadLoad.ThreadLocalMap.Entry objects accessible

      Class tlmClass = Class.forName("java.lang.ThreadLocal$ThreadLocalMap");

      Field tableField = tlmClass.getDeclaredField("table");

      tableField.setAccessible(true);

      Thread thread = Thread.currentThread();

      Object threadLocalMap;

      threadLocalMap = threadLocalsField.get(thread);

      // Check the first map

      checkThreadLocalMapForLeaks(threadLocalMap, tableField);

      // Check the second map

      threadLocalMap = inheritableThreadLocalsField.get(thread);

      checkThreadLocalMapForLeaks(threadLocalMap, tableField);

  }

  private void checkThreadLocalMapForLeaks(Object map, Field internalTableField) throws IllegalAccessException,

      NoSuchFieldException {

    if (map != null) {

      Object[] table = (Object[]) internalTableField.get(map);

      if (table != null) {

        for (int j =0; j < table.length; j++) {

          if (table[j] != null) {

            // Check the key

            Object key = ((Reference) table[j]).get();

            String keyClassName = key.getClass().getName();

            if (key.getClass() == org.apache.log4j.helpers.ThreadLocalMap.class) {

              fail("Found a ThreadLocal with key of type [" + keyClassName + "]");

            }

          }

        }

      }

    }

  }

}

        // clean up if this was the last key

        if (ht.isEmpty()) {

          clear0();

        }