org.apache.tez.runtime.api

Class MergedLogicalInput

java.lang.Object

org.apache.tez.runtime.api.MergedLogicalInput

All Implemented Interfaces:

Input, LogicalInput

@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class MergedLogicalInput
extends Object
implements LogicalInput

A LogicalInput that is used to merge the data from multiple inputs and provide a single Reader to read that data. This Input is not initialized or closed. It is only expected to provide a merged view of the real inputs. It cannot send or receive events

MergedLogicalInput implementations must provide a 2 argument public constructor for Tez to create the Input. The parameters to this constructor are 1) an instance of MergedInputContext and 2) a list of constituent inputs. Tez will take care of initializing and closing the Input after a Processor completes.

Constructor Summary

Constructors

Constructor and Description
MergedLogicalInput(MergedInputContext context, List<Input> inputs) Constructor an instance of the MergedLogicalInputs.

Method Summary

Methods

Modifier and Type	Method and Description
MergedInputContext	getContext()
List<Input>	getInputs()
protected void	informInputReady() Used by the actual MergedInput to notify that it's ready for consumption.
abstract void	setConstituentInputIsReady(Input input) Used by the framework to inform the MergedInput that one of it's constituent Inputs is ready.
void	start() Start any processing that the Input may need to perform.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.tez.runtime.api.Input

getReader

Constructor Detail

MergedLogicalInput

public MergedLogicalInput(MergedInputContext context,
                  List<Input> inputs)

Constructor an instance of the MergedLogicalInputs. Classes extending this one to create a MergedLogicalInput, must provide the same constructor so that Tez can create an instance of the class at runtime.

Parameters:

context - the MergedInputContext which provides the Input with context information within the running task.

inputs - the list of constituen Inputs.

Method Detail

getInputs

public final List<Input> getInputs()

getContext

public final MergedInputContext getContext()

start

public final void start()
                 throws Exception

Description copied from interface: Input

Start any processing that the Input may need to perform. It is the responsibility of the Processor to start Inputs. This typically acts as a signal to Inputs to start any Processing that they may required. A blocking implementation of this method should not be used as a mechanism to determine when an Input is actually ready. This method may be invoked by the framework under certain circumstances, and as such requires the implementation to be non-blocking. Inputs must be written to handle multiple start invocations - typically honoring only the first one.

Specified by:

start in interface Input

Throws:

Exception

informInputReady

protected final void informInputReady()

Used by the actual MergedInput to notify that it's ready for consumption.

setConstituentInputIsReady

public abstract void setConstituentInputIsReady(Input input)

Used by the framework to inform the MergedInput that one of it's constituent Inputs is ready.