private void onOpen(ChannelHandlerContext ctx) throws IOException {
final String nnId = params.namenodeId();
final int bufferSize = params.bufferSize();
final long offset = params.offset();
final long length = params.length();
DefaultHttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
HttpHeaders headers = response.headers();
// Allow the UI to access the file
headers.set(ACCESS_CONTROL_ALLOW_METHODS, GET);
headers.set(ACCESS_CONTROL_ALLOW_ORIGIN, "*");
headers.set(CONTENT_TYPE, APPLICATION_OCTET_STREAM);
headers.set(CONNECTION, CLOSE);
final DFSClient dfsclient = newDfsClient(nnId, conf);
HdfsDataInputStream in =
dfsclient.createWrappedInputStream(dfsclient.open(path, bufferSize, true));
in.seek(offset);
long contentLength = in.getVisibleLength() - offset;
if (length >= 0) {
contentLength = Math.min(contentLength, length);
}
final InputStream data;
if (contentLength >= 0) {
headers.set(CONTENT_LENGTH, contentLength);
data = new LimitInputStream(in, contentLength);
} else {
data = in;
}
ctx.write(response);
ctx.writeAndFlush(
new ChunkedStream(data) {
@Override
public void close() throws Exception {
super.close();
dfsclient.close();
}
})
.addListener(ChannelFutureListener.CLOSE);
}
public static ExtendedBlock getFirstBlock(FileSystem fs, Path path) throws IOException {
HdfsDataInputStream in = (HdfsDataInputStream) ((DistributedFileSystem) fs).open(path);
in.readByte();
return in.getCurrentBlock();
}