/**
* 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!");
}
}
private void validateBounds(final RPCBlockReadRequest req, final long fileLength) {
Preconditions.checkArgument(
req.getOffset() <= fileLength,
"Offset(%s) is larger than file length(%s)",
req.getOffset(),
fileLength);
Preconditions.checkArgument(
req.getLength() == -1 || req.getOffset() + req.getLength() <= fileLength,
"Offset(%s) plus length(%s) is larger than file length(%s)",
req.getOffset(),
req.getLength(),
fileLength);
}
private void handleBlockReadRequest(
final ChannelHandlerContext ctx, final RPCBlockReadRequest req) throws IOException {
final long blockId = req.getBlockId();
final long offset = req.getOffset();
final long len = req.getLength();
final long lockId = req.getLockId();
final long sessionId = req.getSessionId();
BlockReader reader;
try {
reader = mBlockWorker.readBlockRemote(sessionId, blockId, lockId);
} catch (BlockDoesNotExistException e) {
throw new IOException(e);
} catch (InvalidWorkerStateException e) {
throw new IOException(e);
}
try {
req.validate();
final long fileLength = reader.getLength();
validateBounds(req, fileLength);
final long readLength = returnLength(offset, len, fileLength);
RPCBlockReadResponse resp =
new RPCBlockReadResponse(
blockId,
offset,
readLength,
getDataBuffer(req, reader, readLength),
RPCResponse.Status.SUCCESS);
ChannelFuture future = ctx.writeAndFlush(resp);
future.addListener(ChannelFutureListener.CLOSE);
future.addListener(new ClosableResourceChannelListener(reader));
mBlockWorker.accessBlock(sessionId, blockId);
LOG.info("Preparation for responding to remote block request for: {} done.", blockId);
} catch (Exception e) {
LOG.error("The file is not here : {}", e.getMessage(), e);
RPCBlockReadResponse resp =
RPCBlockReadResponse.createErrorResponse(req, RPCResponse.Status.FILE_DNE);
ChannelFuture future = ctx.writeAndFlush(resp);
future.addListener(ChannelFutureListener.CLOSE);
if (reader != null) {
reader.close();
}
}
}
