private static void ensureThatExceptionHandlerIsLast(ChannelPipeline pipeline) {
ChannelInboundHandler exceptionHandler = ChannelExceptionHandler.getInstance();
if (pipeline.last() != exceptionHandler || pipeline.context(exceptionHandler) == null) {
return;
}
pipeline.remove(exceptionHandler);
pipeline.addLast(exceptionHandler);
}
/**
* Creates an instance of {@link NettyPacketReader}. If this is used to read a block remotely, it
* requires the block to be locked beforehand and the lock ID is passed to this class.
*
* @param context the file system context
* @param address the netty data server network address
* @param id the block ID or UFS file ID
* @param offset the offset
* @param len the length to read
* @param lockId the lock ID
* @param sessionId the session ID
* @param type the request type (block or UFS file)
* @throws IOException if it fails to acquire a netty channel
*/
private NettyPacketReader(
FileSystemContext context,
InetSocketAddress address,
long id,
long offset,
long len,
long lockId,
long sessionId,
Protocol.RequestType type)
throws IOException {
Preconditions.checkArgument(offset >= 0 && len > 0);
mContext = context;
mAddress = address;
mId = id;
mStart = offset;
mPosToRead = offset;
mBytesToRead = len;
mRequestType = type;
mChannel = context.acquireNettyChannel(address);
ChannelPipeline pipeline = mChannel.pipeline();
if (!(pipeline.last() instanceof RPCMessageDecoder)) {
throw new RuntimeException(
String.format(
"Channel pipeline has unexpected handlers %s.",
pipeline.last().getClass().getCanonicalName()));
}
mChannel.pipeline().addLast(new PacketReadHandler());
Protocol.ReadRequest readRequest =
Protocol.ReadRequest.newBuilder()
.setId(id)
.setOffset(offset)
.setLength(len)
.setLockId(lockId)
.setSessionId(sessionId)
.setType(type)
.build();
mChannel
.writeAndFlush(new RPCProtoMessage(readRequest))
.addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
}