/// <summary>
/// create a worker for a file-at-a-time hdfs reader
/// </summary>
/// <param name="client">Hdfs client used to read files</param>
/// <param name="deserialize">function to take a stream consisting of an entire webhdfs file, and return a sequence
/// of batches, each containing an arraysegment of output records</param>
public DfsFileWorker(
HdfsClientBase client, Func <Stream, IEnumerable <ArraySegment <TOutput> > > deserialize)
{
// cache all the addresses the local node is listening on
this.localAddresses = Dns.GetHostAddresses(Dns.GetHostName());
this.deserialize = deserialize;
this.client = client;
}
/// <summary>
/// create a worker for deserializing lines of text from an Hdfs file
/// </summary>
/// <param name="client">Hdfs client to use for reading data</param>
/// <param name="batchSize">number of lines to return at a time</param>
public DfsTextWorker(HdfsClientBase client, int batchSize)
: base(
// use 4k blocks when scanning past the end of the block to find the end of the final line
4 * 1024,
(item, stream) => SyncToNextLine(stream),
(item, stream) => Deserialize(stream, batchSize),
client)
{
}
/// <summary>
/// create a worker to read dfs files broken into blocks
/// </summary>
/// <param name="syncRequestLength">size of each dfs request when seeking past the end of the block for the start of the
/// next record. If records are expected to be small this should also be small, to avoid prefetching and buffering a lot of the
/// next block's data</param>
/// <param name="syncToNextRecord">action to sync to the start of the next record. The first argument is the block item
/// being read, which may contain metadata about sync markers. The second argument is the stream to scan.</param>
/// <param name="deserialize">function to deserialize records in a stream</param>
/// <param name="client">client used to read hdfs data</param>
public DfsBlockWorker(
int syncRequestLength,
Action <TItem, Stream> syncToNextRecord,
Func <TItem, Stream, IEnumerable <ArraySegment <TOutput> > > deserialize,
HdfsClientBase client)
{
// cache the local IP addresses
this.localAddresses = Dns.GetHostAddresses(Dns.GetHostName());
this.syncRequestLength = syncRequestLength;
this.syncToNextRecord = syncToNextRecord;
this.deserialize = deserialize;
this.client = client;
}
/// <summary>
/// create a coordinator for reading Dfs files with fixed-length blocks, made of text records
/// </summary>
/// <param name="client">client used for reading Hdfs data and metadata</param>
public DfsTextCoordinator(HdfsClientBase client) : base(client)
{
}
/// <summary>
/// return a new coordinator for a block-based HDFS reader
/// </summary>
/// <param name="client">hdfs client used to read files and metadata</param>
public DfsBlockCoordinator(HdfsClientBase client) : base(client)
{
}
/// <summary>
/// create a new coordinator for file-at-a-time dfs reads
/// </summary>
/// <param name="client">hdfs client</param>
public DfsFileCoordinator(HdfsClientBase client) : base(client)
{
}
/// <summary>
/// return a new coordinator for a dfs reader
/// </summary>
/// <param name="client">hdfs client</param>
public DfsBaseCoordinator(HdfsClientBase client)
{
this.client = client;
this.dataNodes = new Dictionary <IPAddress, IPEndPoint>();
}
/// <summary>
/// A file with the specified path.
/// </summary>
/// <param name="path">Path to the file.</param>
/// <param name="client">Azure client.</param>
/// <param name="config">Cluster configuration.</param>
/// <param name="job">Job accessing this file.</param>
/// <param name="jobFolderUri">Uri to base folder.</param>
/// <param name="isFolder">If true this must be a folder.</param>
/// <param name="canCache">True if the file can be cached (it is immutable for sure).</param>
public DfsFile(ClusterConfiguration config, Uri jobFolderUri, DryadLinqJobSummary job, HdfsClientBase client, string path, bool canCache, bool isFolder)
: base(config, job)
{
this.client = client;
this.Exception = null;
this.baseUri = jobFolderUri;
this.uri = UriFromPath(jobFolderUri, path);
this.ShouldCacheLocally = canCache;
this.RepresentsAFolder = isFolder;
this.size = -1;
Console.WriteLine("DfsFile Uri={0}", this.uri);
if (!string.IsNullOrEmpty(CachedClusterResidentObject.CacheDirectory))
this.LocalCachePath = Path.Combine(CachedClusterResidentObject.CacheDirectory, PathFromUri(this.baseUri, this.uri));
}
/// <summary>
/// Must be called after setting all properties.
/// Returns true if initialization succeeds.
/// </summary>
public override string Initialize()
{
try
{
this.DfsClient = new HdfsClient(this.UserName);
return null;
}
catch (Exception ex)
{
Console.WriteLine(ex);
return ex.Message;
}
}
