/**
 * 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.hbase.util;

import static org.junit.Assert.assertTrue;

import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.hadoop.hbase.HBaseClassTestRule;
import org.apache.hadoop.hbase.testclassification.MiscTests;
import org.apache.hadoop.hbase.testclassification.SmallTests;
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Category({MiscTests.class, SmallTests.class})
public class TestThreads {

  @ClassRule
  public static final HBaseClassTestRule CLASS_RULE =
      HBaseClassTestRule.forClass(TestThreads.class);

  private static final Logger LOG = LoggerFactory.getLogger(TestThreads.class);

  private static final int SLEEP_TIME_MS = 3000;
  private static final int TOLERANCE_MS = (int) (0.10 * SLEEP_TIME_MS);

  private final AtomicBoolean wasInterrupted = new AtomicBoolean(false);

  @Test
  public void testSleepWithoutInterrupt() throws InterruptedException {
    Thread sleeper = new Thread(new Runnable() {
      @Override
      public void run() {
        LOG.debug("Sleeper thread: sleeping for " + SLEEP_TIME_MS);
        Threads.sleepWithoutInterrupt(SLEEP_TIME_MS);
        LOG.debug("Sleeper thread: finished sleeping");
        wasInterrupted.set(Thread.currentThread().isInterrupted());
      }
    });
    LOG.debug("Starting sleeper thread (" + SLEEP_TIME_MS + " ms)");
    sleeper.start();
    long startTime = System.currentTimeMillis();
    LOG.debug("Main thread: sleeping for 200 ms");
    Threads.sleep(200);

    LOG.debug("Interrupting the sleeper thread and sleeping for 500 ms");
    sleeper.interrupt();
    Threads.sleep(500);

    LOG.debug("Interrupting the sleeper thread and sleeping for 800 ms");
    sleeper.interrupt();
    Threads.sleep(800);

    LOG.debug("Interrupting the sleeper thread again");
    sleeper.interrupt();
    sleeper.join();

    assertTrue("sleepWithoutInterrupt did not preserve the thread's " +
        "interrupted status", wasInterrupted.get());

    long timeElapsed = System.currentTimeMillis() - startTime;
    // We expect to wait at least SLEEP_TIME_MS, but we can wait more if there is a GC.
    assertTrue("Elapsed time " + timeElapsed + " ms is out of the expected " +
        " sleep time of " + SLEEP_TIME_MS, SLEEP_TIME_MS - timeElapsed < TOLERANCE_MS);
    LOG.debug("Target sleep time: " + SLEEP_TIME_MS + ", time elapsed: " +
        timeElapsed);
  }
}
