Java tutorial
/* * 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.hdfs.server.blockmanagement; import java.util.Arrays; import java.util.Iterator; import java.util.Random; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.hdfs.protocol.DatanodeID; import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor; import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList; import org.apache.hadoop.hdfs.server.namenode.CachedBlock; import org.junit.Assert; import org.junit.Test; public class TestCachedBlocksList { public static final Log LOG = LogFactory.getLog(TestCachedBlocksList.class); @Test(timeout = 60000) public void testSingleList() { DatanodeDescriptor dn = new DatanodeDescriptor( new DatanodeID("127.0.0.1", "localhost", "abcd", 5000, 5001, 5002, 5003)); CachedBlock[] blocks = new CachedBlock[] { new CachedBlock(0L, (short) 1, true), new CachedBlock(1L, (short) 1, true), new CachedBlock(2L, (short) 1, true), }; // check that lists are empty Assert.assertTrue("expected pending cached list to start off empty.", !dn.getPendingCached().iterator().hasNext()); Assert.assertTrue("expected cached list to start off empty.", !dn.getCached().iterator().hasNext()); Assert.assertTrue("expected pending uncached list to start off empty.", !dn.getPendingUncached().iterator().hasNext()); // add a block to the back Assert.assertTrue(dn.getCached().add(blocks[0])); Assert.assertTrue("expected pending cached list to still be empty.", !dn.getPendingCached().iterator().hasNext()); Assert.assertEquals("failed to insert blocks[0]", blocks[0], dn.getCached().iterator().next()); Assert.assertTrue("expected pending uncached list to still be empty.", !dn.getPendingUncached().iterator().hasNext()); // add another block to the back Assert.assertTrue(dn.getCached().add(blocks[1])); Iterator<CachedBlock> iter = dn.getCached().iterator(); Assert.assertEquals(blocks[0], iter.next()); Assert.assertEquals(blocks[1], iter.next()); Assert.assertTrue(!iter.hasNext()); // add a block to the front Assert.assertTrue(dn.getCached().addFirst(blocks[2])); iter = dn.getCached().iterator(); Assert.assertEquals(blocks[2], iter.next()); Assert.assertEquals(blocks[0], iter.next()); Assert.assertEquals(blocks[1], iter.next()); Assert.assertTrue(!iter.hasNext()); // remove a block from the middle Assert.assertTrue(dn.getCached().remove(blocks[0])); iter = dn.getCached().iterator(); Assert.assertEquals(blocks[2], iter.next()); Assert.assertEquals(blocks[1], iter.next()); Assert.assertTrue(!iter.hasNext()); // remove all blocks dn.getCached().clear(); Assert.assertTrue("expected cached list to be empty after clear.", !dn.getPendingCached().iterator().hasNext()); } private void testAddElementsToList(CachedBlocksList list, CachedBlock[] blocks) { Assert.assertTrue("expected list to start off empty.", !list.iterator().hasNext()); for (CachedBlock block : blocks) { Assert.assertTrue(list.add(block)); } } private void testRemoveElementsFromList(Random r, CachedBlocksList list, CachedBlock[] blocks) { int i = 0; for (Iterator<CachedBlock> iter = list.iterator(); iter.hasNext();) { Assert.assertEquals(blocks[i], iter.next()); i++; } if (r.nextBoolean()) { LOG.info("Removing via iterator"); for (Iterator<CachedBlock> iter = list.iterator(); iter.hasNext();) { iter.next(); iter.remove(); } } else { LOG.info("Removing in pseudo-random order"); CachedBlock[] remainingBlocks = Arrays.copyOf(blocks, blocks.length); for (int removed = 0; removed < remainingBlocks.length;) { int toRemove = r.nextInt(remainingBlocks.length); if (remainingBlocks[toRemove] != null) { Assert.assertTrue(list.remove(remainingBlocks[toRemove])); remainingBlocks[toRemove] = null; removed++; } } } Assert.assertTrue("expected list to be empty after everything " + "was removed.", !list.iterator().hasNext()); } @Test(timeout = 60000) public void testMultipleLists() { DatanodeDescriptor[] datanodes = new DatanodeDescriptor[] { new DatanodeDescriptor(new DatanodeID("127.0.0.1", "localhost", "abcd", 5000, 5001, 5002, 5003)), new DatanodeDescriptor(new DatanodeID("127.0.1.1", "localhost", "efgh", 6000, 6001, 6002, 6003)), }; CachedBlocksList[] lists = new CachedBlocksList[] { datanodes[0].getPendingCached(), datanodes[0].getCached(), datanodes[1].getPendingCached(), datanodes[1].getCached(), datanodes[1].getPendingUncached(), }; final int NUM_BLOCKS = 8000; CachedBlock[] blocks = new CachedBlock[NUM_BLOCKS]; for (int i = 0; i < NUM_BLOCKS; i++) { blocks[i] = new CachedBlock(i, (short) i, true); } Random r = new Random(654); for (CachedBlocksList list : lists) { testAddElementsToList(list, blocks); } for (CachedBlocksList list : lists) { testRemoveElementsFromList(r, list, blocks); } } }