public HdfsStreamReader(HdfsInstance instance, string dfsPath, long offset, long length, int byteBufferSize)
: base(byteBufferSize)
{
this.reader = instance.OpenReader(dfsPath);
this.offset = offset;
this.bytesToRead = length;
}
public override int Read(byte[] buffer, int offset, int count)
{
int numBytesRead = _cachedReader.ReadBlock(_readPosition, buffer, offset, count);
if (numBytesRead == 0 && offset < Length)
{
// the reader has a stale idea of the file length; reopen it and try again
_cachedReader.Dispose();
string logPath = _logUri.AbsolutePath;
_cachedReader = _hdfs.OpenReader(logPath);
numBytesRead = _cachedReader.ReadBlock(_readPosition, buffer, offset, count);
}
_readPosition += numBytesRead;
return(numBytesRead);
}
public HdfsLogReaderStream(Uri logUri)
{
_logUri = logUri;
_readPosition = 0; // this is the current read position
try
{
_hdfs = new HdfsInstance(_logUri);
string logPath = _logUri.AbsolutePath;
_cachedReader = _hdfs.OpenReader(logPath);
}
catch (Exception e)
{
throw new ApplicationException("HdfsLogReaderStream failed to open reader", e);
}
}