org.apache.flink.runtime.io.network.api.writer

Interface ChannelSelector<T extends org.apache.flink.core.io.IOReadableWritable>

Type Parameters:

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

All Known Implementing Classes:

OutputEmitter, RoundRobinChannelSelector

public interface ChannelSelector<T extends org.apache.flink.core.io.IOReadableWritable>

The ChannelSelector determines to which logical channels a record should be written to.

Method Summary

Modifier and Type	Method and 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.