/*
    * 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.regionserver.wal;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertNotSame;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.testclassification.RegionServerTests;
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  @Category({ RegionServerTests.class, SmallTests.class })
  public class TestSyncFutureCache {
  
    @Test
    public void testSyncFutureCacheLifeCycle() throws Exception {
      final Configuration conf = HBaseConfiguration.create();
      final SyncFutureCache cache = new SyncFutureCache(conf);
      try {
        SyncFuture future0 = cache.getIfPresentOrNew().reset(0);
        assertNotNull(future0);
        // Get another future from the same thread, should be different one.
        SyncFuture future1 = cache.getIfPresentOrNew().reset(1);
        assertNotNull(future1);
        assertNotSame(future0, future1);
        cache.offer(future1);
        // Should override.
        cache.offer(future0);
        SyncFuture future3 = cache.getIfPresentOrNew();
        // Should return the cached entry that was first offered back.
        assertEquals(future3, future0);
        final SyncFuture[] future4 = new SyncFuture[1];
        // From a different thread
        Thread t = new Thread(new Runnable() {
          @Override public void run() {
            future4[0] = cache.getIfPresentOrNew().reset(4);
          }
        });
        t.start();
        t.join();
        assertNotNull(future4[0]);
        assertNotSame(future3, future4[0]);
        // Clean up
        cache.offer(future3);
        cache.offer(future4[0]);
      } finally {
        cache.clear();
      }
    }
  }