/// <summary>
/// Queries datanodes for the blocks specified in <code>datanodeBlocks</code>,
/// making one RPC to each datanode.
/// </summary>
/// <remarks>
/// Queries datanodes for the blocks specified in <code>datanodeBlocks</code>,
/// making one RPC to each datanode. These RPCs are made in parallel using a
/// threadpool.
/// </remarks>
/// <param name="datanodeBlocks">Map of datanodes to the blocks present on the DN</param>
/// <returns>metadatas Map of datanodes to block metadata of the DN</returns>
/// <exception cref="Org.Apache.Hadoop.Hdfs.Security.Token.Block.InvalidBlockTokenException
/// ">if client does not have read access on a requested block</exception>
internal static IDictionary <DatanodeInfo, HdfsBlocksMetadata> QueryDatanodesForHdfsBlocksMetadata
(Configuration conf, IDictionary <DatanodeInfo, IList <LocatedBlock> > datanodeBlocks
, int poolsize, int timeoutMs, bool connectToDnViaHostname)
{
IList <BlockStorageLocationUtil.VolumeBlockLocationCallable> callables = CreateVolumeBlockLocationCallables
(conf, datanodeBlocks, timeoutMs, connectToDnViaHostname, Trace.CurrentSpan());
// Use a thread pool to execute the Callables in parallel
IList <Future <HdfsBlocksMetadata> > futures = new AList <Future <HdfsBlocksMetadata> >
();
ExecutorService executor = new ScheduledThreadPoolExecutor(poolsize);
try
{
futures = executor.InvokeAll(callables, timeoutMs, TimeUnit.Milliseconds);
}
catch (Exception)
{
}
// Swallow the exception here, because we can return partial results
executor.Shutdown();
IDictionary <DatanodeInfo, HdfsBlocksMetadata> metadatas = Maps.NewHashMapWithExpectedSize
(datanodeBlocks.Count);
// Fill in metadatas with results from DN RPCs, where possible
for (int i = 0; i < futures.Count; i++)
{
BlockStorageLocationUtil.VolumeBlockLocationCallable callable = callables[i];
DatanodeInfo datanode = callable.GetDatanodeInfo();
Future <HdfsBlocksMetadata> future = futures[i];
try
{
HdfsBlocksMetadata metadata = future.Get();
metadatas[callable.GetDatanodeInfo()] = metadata;
}
catch (CancellationException e)
{
Log.Info("Cancelled while waiting for datanode " + datanode.GetIpcAddr(false) + ": "
+ e.ToString());
}
catch (ExecutionException e)
{
Exception t = e.InnerException;
if (t is InvalidBlockTokenException)
{
Log.Warn("Invalid access token when trying to retrieve " + "information from datanode "
+ datanode.GetIpcAddr(false));
throw (InvalidBlockTokenException)t;
}
else
{
if (t is NotSupportedException)
{
Log.Info("Datanode " + datanode.GetIpcAddr(false) + " does not support" + " required #getHdfsBlocksMetadata() API"
);
throw (NotSupportedException)t;
}
else
{
Log.Info("Failed to query block locations on datanode " + datanode.GetIpcAddr(false
) + ": " + t);
}
}
if (Log.IsDebugEnabled())
{
Log.Debug("Could not fetch information from datanode", t);
}
}
catch (Exception)
{
// Shouldn't happen, because invokeAll waits for all Futures to be ready
Log.Info("Interrupted while fetching HdfsBlocksMetadata");
}
}
return(metadatas);
}