/**
* Verify that the NameNode is able to still use <tt>READ_ONLY_SHARED</tt> replicas even when the
* single NORMAL replica is offline (and the effective replication count is 0).
*/
@Test
public void testNormalReplicaOffline() throws Exception {
// Stop the datanode hosting the NORMAL replica
cluster.stopDataNode(normalDataNode.getXferAddr());
// Force NameNode to detect that the datanode is down
BlockManagerTestUtil.noticeDeadDatanode(cluster.getNameNode(), normalDataNode.getXferAddr());
// The live replica count should now be zero (since the NORMAL replica is offline)
NumberReplicas numberReplicas = blockManager.countNodes(block);
assertThat(numberReplicas.liveReplicas(), is(0));
// The block should be reported as under-replicated
BlockManagerTestUtil.updateState(blockManager);
assertThat(blockManager.getUnderReplicatedBlocksCount(), is(1L));
// The BlockManager should be able to heal the replication count back to 1
// by triggering an inter-datanode replication from one of the READ_ONLY_SHARED replicas
BlockManagerTestUtil.computeAllPendingWork(blockManager);
DFSTestUtil.waitForReplication(cluster, extendedBlock, 1, 1, 0);
// There should now be 2 *locations* for the block, and 1 *replica*
assertThat(getLocatedBlock().getLocations().length, is(2));
validateNumberReplicas(1);
}
private void validateNumberReplicas(int expectedReplicas) throws IOException {
NumberReplicas numberReplicas = blockManager.countNodes(block);
assertThat(numberReplicas.liveReplicas(), is(expectedReplicas));
assertThat(numberReplicas.excessReplicas(), is(0));
assertThat(numberReplicas.corruptReplicas(), is(0));
assertThat(numberReplicas.decommissionedReplicas(), is(0));
assertThat(numberReplicas.replicasOnStaleNodes(), is(0));
BlockManagerTestUtil.updateState(blockManager);
assertThat(blockManager.getUnderReplicatedBlocksCount(), is(0L));
assertThat(blockManager.getExcessBlocksCount(), is(0L));
}