/*
 *
 * 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.replication;


import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.HBaseTestingUtility;
import org.apache.hadoop.hbase.LargeTests;
import org.apache.hadoop.hbase.UnknownScannerException;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.junit.Test;
import org.junit.experimental.categories.Category;

import static org.junit.Assert.fail;

@Category(LargeTests.class)
public class TestReplicationQueueFailover extends TestReplicationBase {

  private static final Log LOG = LogFactory.getLog(TestReplicationQueueFailover.class);

  /**
   * Load up multiple tables over 2 region servers and kill a source during
   * the upload. The failover happens internally.
   *
   * WARNING this test sometimes fails because of HBASE-3515
   *
   * @throws Exception
   */
  @Test(timeout=300000)
  public void queueFailover() throws Exception {
    // killing the RS with .META. can result into failed puts until we solve
    // IO fencing
    int rsToKill1 =
        utility1.getHBaseCluster().getServerWithMeta() == 0 ? 1 : 0;
    int rsToKill2 =
        utility2.getHBaseCluster().getServerWithMeta() == 0 ? 1 : 0;

    // Takes about 20 secs to run the full loading, kill around the middle
    Thread killer1 = killARegionServer(utility1, 7500, rsToKill1);
    Thread killer2 = killARegionServer(utility2, 10000, rsToKill2);

    LOG.info("Start loading table");
    int initialCount = utility1.loadTable(htable1, famName);
    LOG.info("Done loading table");
    killer1.join(5000);
    killer2.join(5000);
    LOG.info("Done waiting for threads");

    Result[] res;
    while (true) {
      try {
        Scan scan = new Scan();
        ResultScanner scanner = htable1.getScanner(scan);
        res = scanner.next(initialCount);
        scanner.close();
        break;
      } catch (UnknownScannerException ex) {
        LOG.info("Cluster wasn't ready yet, restarting scanner");
      }
    }
    // Test we actually have all the rows, we may miss some because we
    // don't have IO fencing.
    if (res.length != initialCount) {
      LOG.warn("We lost some rows on the master cluster!");
      // We don't really expect the other cluster to have more rows
      initialCount = res.length;
    }

    int lastCount = 0;

    final long start = System.currentTimeMillis();
    int i = 0;
    while (true) {
      if (i==NB_RETRIES-1) {
        fail("Waited too much time for queueFailover replication. " +
            "Waited "+(System.currentTimeMillis() - start)+"ms.");
      }
      Scan scan2 = new Scan();
      ResultScanner scanner2 = htable2.getScanner(scan2);
      Result[] res2 = scanner2.next(initialCount * 2);
      scanner2.close();
      if (res2.length < initialCount) {
        if (lastCount < res2.length) {
          i--; // Don't increment timeout if we make progress
        } else {
          i++;
        }
        lastCount = res2.length;
        LOG.info("Only got " + lastCount + " rows instead of " +
            initialCount + " current i=" + i);
        Thread.sleep(SLEEP_TIME*2);
      } else {
        break;
      }
    }
  }

  private static Thread killARegionServer(final HBaseTestingUtility utility,
                                          final long timeout, final int rs) {
    Thread killer = new Thread() {
      public void run() {
        try {
          Thread.sleep(timeout);
          utility.expireRegionServerSession(rs);
        } catch (Exception e) {
          LOG.error("Couldn't kill a region server", e);
        }
      }
    };
    killer.setDaemon(true);
    killer.start();
    return killer;
  }
}