public virtual void TestCopyOnWrite()
{
Configuration conf = new HdfsConfiguration();
MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).Build();
FileSystem fs = cluster.GetFileSystem();
IPEndPoint addr = new IPEndPoint("localhost", cluster.GetNameNodePort());
DFSClient client = new DFSClient(addr, conf);
try
{
// create a new file, write to it and close it.
//
Path file1 = new Path("/filestatus.dat");
FSDataOutputStream stm = AppendTestUtil.CreateFile(fs, file1, 1);
WriteFile(stm);
stm.Close();
// Get a handle to the datanode
DataNode[] dn = cluster.ListDataNodes();
NUnit.Framework.Assert.IsTrue("There should be only one datanode but found " + dn
.Length, dn.Length == 1);
LocatedBlocks locations = client.GetNamenode().GetBlockLocations(file1.ToString()
, 0, long.MaxValue);
IList <LocatedBlock> blocks = locations.GetLocatedBlocks();
//
// Create hard links for a few of the blocks
//
for (int i = 0; i < blocks.Count; i = i + 2)
{
ExtendedBlock b = blocks[i].GetBlock();
FilePath f = DataNodeTestUtils.GetFile(dn[0], b.GetBlockPoolId(), b.GetLocalBlock
().GetBlockId());
FilePath link = new FilePath(f.ToString() + ".link");
System.Console.Out.WriteLine("Creating hardlink for File " + f + " to " + link);
HardLink.CreateHardLink(f, link);
}
//
// Detach all blocks. This should remove hardlinks (if any)
//
for (int i_1 = 0; i_1 < blocks.Count; i_1++)
{
ExtendedBlock b = blocks[i_1].GetBlock();
System.Console.Out.WriteLine("testCopyOnWrite detaching block " + b);
NUnit.Framework.Assert.IsTrue("Detaching block " + b + " should have returned true"
, DataNodeTestUtils.UnlinkBlock(dn[0], b, 1));
}
// Since the blocks were already detached earlier, these calls should
// return false
//
for (int i_2 = 0; i_2 < blocks.Count; i_2++)
{
ExtendedBlock b = blocks[i_2].GetBlock();
System.Console.Out.WriteLine("testCopyOnWrite detaching block " + b);
NUnit.Framework.Assert.IsTrue("Detaching block " + b + " should have returned false"
, !DataNodeTestUtils.UnlinkBlock(dn[0], b, 1));
}
}
finally
{
client.Close();
fs.Close();
cluster.Shutdown();
}
}