/**
* Returns the appropriate {@link DataBuffer} representing the data to send, depending on the
* configurable transfer type.
*
* @param req The initiating {@link RPCBlockReadRequest}
* @param reader The {@link BlockReader} for the block to read
* @param readLength The length, in bytes, of the data to read from the block
* @return a {@link DataBuffer} representing the data
* @throws IOException
* @throws IllegalArgumentException
*/
private DataBuffer getDataBuffer(RPCBlockReadRequest req, BlockReader reader, long readLength)
throws IOException, IllegalArgumentException {
switch (mTransferType) {
case MAPPED:
ByteBuffer data = reader.read(req.getOffset(), (int) readLength);
return new DataByteBuffer(data, readLength);
case TRANSFER: // intend to fall through as TRANSFER is the default type.
default:
if (reader.getChannel() instanceof FileChannel) {
return new DataFileChannel(
(FileChannel) reader.getChannel(), req.getOffset(), readLength);
}
reader.close();
throw new IllegalArgumentException("Only FileChannel is supported!");
}
}
