How to use

remove

method

in

org.apache.hadoop.hdfs.server.blockmanagement.Host2NodesMap

/** Physically remove node from datanodeMap. */
private void wipeDatanode(final DatanodeID node) {
 final String key = node.getDatanodeUuid();
 synchronized (this) {
  host2DatanodeMap.remove(datanodeMap.remove(key));
 }
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".wipeDatanode("
    + node + "): storage " + key 
    + " is removed from datanodeMap.");
 }
}

/** Add a datanode. */
void addDatanode(final DatanodeDescriptor node) {
 // To keep host2DatanodeMap consistent with datanodeMap,
 // remove  from host2DatanodeMap the datanodeDescriptor removed
 // from datanodeMap before adding node to host2DatanodeMap.
 synchronized(this) {
  host2DatanodeMap.remove(datanodeMap.put(node.getDatanodeUuid(), node));
 }
 networktopology.add(node); // may throw InvalidTopologyException
 host2DatanodeMap.add(node);
 checkIfClusterIsNowMultiRack(node);
 resolveUpgradeDomain(node);
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".addDatanode: "
    + "node " + node + " is added to datanodeMap.");
 }
}

/** Physically remove node from datanodeMap. */
private void wipeDatanode(final DatanodeID node) {
 final String key = node.getDatanodeUuid();
 synchronized (datanodeMap) {
  host2DatanodeMap.remove(datanodeMap.remove(key));
 }
 // Also remove all block invalidation tasks under this node
 blockManager.removeFromInvalidates(new DatanodeInfo(node));
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".wipeDatanode("
    + node + "): storage " + key 
    + " is removed from datanodeMap.");
 }
}

/** Add a datanode. */
void addDatanode(final DatanodeDescriptor node) {
 // To keep host2DatanodeMap consistent with datanodeMap,
 // remove  from host2DatanodeMap the datanodeDescriptor removed
 // from datanodeMap before adding node to host2DatanodeMap.
 synchronized(datanodeMap) {
  host2DatanodeMap.remove(datanodeMap.put(node.getDatanodeUuid(), node));
 }
 networktopology.add(node); // may throw InvalidTopologyException
 host2DatanodeMap.add(node);
 checkIfClusterIsNowMultiRack(node);
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".addDatanode: "
    + "node " + node + " is added to datanodeMap.");
 }
}

/** Physically remove node from datanodeMap. */
private void wipeDatanode(final DatanodeID node) {
 final String key = node.getDatanodeUuid();
 synchronized (datanodeMap) {
  host2DatanodeMap.remove(datanodeMap.remove(key));
 }
 // Also remove all block invalidation tasks under this node
 blockManager.removeFromInvalidates(new DatanodeInfo(node));
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".wipeDatanode("
    + node + "): storage " + key 
    + " is removed from datanodeMap.");
 }
}

/** Add a datanode. */
void addDatanode(final DatanodeDescriptor node) {
 // To keep host2DatanodeMap consistent with datanodeMap,
 // remove  from host2DatanodeMap the datanodeDescriptor removed
 // from datanodeMap before adding node to host2DatanodeMap.
 synchronized(datanodeMap) {
  host2DatanodeMap.remove(datanodeMap.put(node.getDatanodeUuid(), node));
 }
 networktopology.add(node); // may throw InvalidTopologyException
 host2DatanodeMap.add(node);
 checkIfClusterIsNowMultiRack(node);
 if (LOG.isDebugEnabled()) {
  LOG.debug(getClass().getSimpleName() + ".addDatanode: "
    + "node " + node + " is added to datanodeMap.");
 }
}

@Test
public void testRemove() throws Exception {
 DatanodeDescriptor nodeNotInMap =
  DFSTestUtil.getDatanodeDescriptor("3.3.3.3", "/d1/r4");
 assertFalse(map.remove(nodeNotInMap));
 
 assertTrue(map.remove(dataNodes[0]));
 assertTrue(map.getDatanodeByHost("1.1.1.1.")==null);
 assertTrue(map.getDatanodeByHost("2.2.2.2")==dataNodes[1]);
 DatanodeDescriptor node = map.getDatanodeByHost("3.3.3.3");
 assertTrue(node==dataNodes[2] || node==dataNodes[3]);
 assertNull(map.getDatanodeByHost("4.4.4.4"));
 
 assertTrue(map.remove(dataNodes[2]));
 assertNull(map.getDatanodeByHost("1.1.1.1"));
 assertEquals(map.getDatanodeByHost("2.2.2.2"), dataNodes[1]);
 assertEquals(map.getDatanodeByHost("3.3.3.3"), dataNodes[3]);
 
 assertTrue(map.remove(dataNodes[3]));
 assertNull(map.getDatanodeByHost("1.1.1.1"));
 assertEquals(map.getDatanodeByHost("2.2.2.2"), dataNodes[1]);
 assertNull(map.getDatanodeByHost("3.3.3.3"));
 
 assertFalse(map.remove(null));
 assertTrue(map.remove(dataNodes[1]));
 assertFalse(map.remove(dataNodes[1]));
}