NettyConnectionReader (Flink : Runtime 2.0-preview1 API)

All Known Implementing Classes:

NettyConnectionReaderImpl
```
public interface NettyConnectionReader
```
NettyConnectionReader is used by TierConsumerAgent to read buffer from netty.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`int`	`peekNextBufferSubpartitionId()`	Returns the index of the subpartition where the next buffer locates, or -1 if there is no buffer available and the subpartition to be consumed is not determined.
`Optional<Buffer>`	`readBuffer(int subpartitionId, int segmentId)`	Read a buffer from netty connection.

- Method Detail
  - peekNextBufferSubpartitionId
```
int peekNextBufferSubpartitionId()
                          throws IOException
```
    Returns the index of the subpartition where the next buffer locates, or -1 if there is no buffer available and the subpartition to be consumed is not determined.
    
    Throws:
    
    IOException
  - readBuffer
```
Optional<Buffer> readBuffer(int subpartitionId,
                            int segmentId)
```
    Read a buffer from netty connection.
    
    Parameters:
    
    subpartitionId - the subpartition where the buffer locates.
    
    segmentId - segment id indicates the id of segment.
    
    Returns:
    
    Optional.empty() will be returned if there is no buffer sent from netty connection otherwise a buffer will be returned.