ChannelSelector (Flink : 2.0-SNAPSHOT API)

Type Parameters:

T - the type of record which is sent through the attached output gate

All Known Implementing Classes:

BinaryHashPartitioner, BroadcastPartitioner, CustomPartitionerWrapper, ForwardForConsecutiveHashPartitioner, ForwardForUnspecifiedPartitioner, ForwardPartitioner, GlobalPartitioner, KeyGroupStreamPartitioner, OutputEmitter, RebalancePartitioner, RescalePartitioner, RoundRobinChannelSelector, ShufflePartitioner, StreamPartitioner
```
public interface ChannelSelector<T extends IOReadableWritable>
```
The ChannelSelector determines to which logical channels a record should be written to.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`isBroadcast()`	Returns whether the channel selector always selects all the output channels.
`int`	`selectChannel(T record)`	Returns the logical channel index, to which the given record should be written.
`void`	`setup(int numberOfChannels)`	Initializes the channel selector with the number of output channels.

- Method Detail
  - setup
```
void setup(int numberOfChannels)
```
    Initializes the channel selector with the number of output channels.
    
    Parameters:
    
    numberOfChannels - the total number of output channels which are attached to respective output gate.
  - selectChannel
```
int selectChannel(T record)
```
    Returns the logical channel index, to which the given record should be written. It is illegal to call this method for broadcast channel selectors and this method can remain not implemented in that case (for example by throwing UnsupportedOperationException).
    
    Parameters:
    
    record - the record to determine the output channels for.
    
    Returns:
    
    an integer number which indicates the index of the output channel through which the record shall be forwarded.
  - isBroadcast
```
boolean isBroadcast()
```
    Returns whether the channel selector always selects all the output channels.
    
    Returns:
    
    true if the selector is for broadcast mode.