Package org.apache.flink.api.common.functions

Class AbstractRichFunction

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

All Implemented Interfaces:

Serializable, org.apache.flink.api.common.functions.Function, RichFunction

Direct Known Subclasses:

BulkIterationBase.TerminationCriterionMapper, NoOpFunction, RichAggregateFunction, RichCoGroupFunction, RichCrossFunction, RichFilterFunction, RichFlatJoinFunction, RichFlatMapFunction, RichGroupCombineFunction, RichGroupReduceFunction, RichJoinFunction, RichMapFunction, RichMapPartitionFunction, RichReduceFunction

@Public
public abstract class AbstractRichFunction
extends Object
implements RichFunction, Serializable

An abstract stub implementation for rich user-defined functions. Rich functions have additional methods for initialization (RichFunction.open(OpenContext)) and teardown (close()), as well as access to their runtime execution context via getRuntimeContext().

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
AbstractRichFunction()

Method Summary

Modifier and Type	Method	Description
void	close()	Tear-down method for the user code.
IterationRuntimeContext	getIterationRuntimeContext()	Gets a specialized version of the RuntimeContext, which has additional information about the iteration in which the function is executed.
RuntimeContext	getRuntimeContext()	Gets the context that contains information about the UDF's runtime, such as the parallelism of the function, the subtask index of the function, or the name of the task that executes the function.
void	open(Configuration parameters)	Initialization method for the function.
void	setRuntimeContext(RuntimeContext t)	Sets the function's runtime context.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.flink.api.common.functions.RichFunction

open

Constructor Detail

AbstractRichFunction

public AbstractRichFunction()

Method Detail

setRuntimeContext

public void setRuntimeContext(RuntimeContext t)

Description copied from interface: RichFunction

Sets the function's runtime context. Called by the framework when creating a parallel instance of the function.

Specified by:

setRuntimeContext in interface RichFunction

Parameters:

t - The runtime context.

getRuntimeContext

public RuntimeContext getRuntimeContext()

Description copied from interface: RichFunction

Gets the context that contains information about the UDF's runtime, such as the parallelism of the function, the subtask index of the function, or the name of the task that executes the function.

The RuntimeContext also gives access to the Accumulators and the DistributedCache.

Specified by:

getRuntimeContext in interface RichFunction

Returns:

The UDF's runtime context.

getIterationRuntimeContext

public IterationRuntimeContext getIterationRuntimeContext()

Description copied from interface: RichFunction

Gets a specialized version of the RuntimeContext, which has additional information about the iteration in which the function is executed. This IterationRuntimeContext is only available if the function is part of an iteration. Otherwise, this method throws an exception.

Specified by:

getIterationRuntimeContext in interface RichFunction

Returns:

The IterationRuntimeContext.

open

public void open(Configuration parameters)
          throws Exception

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyFilter extends RichFilterFunction<String> {

     private String searchString;

     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }

     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Parameters:

parameters - The configuration containing the parameters attached to the contract.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

See Also:

Configuration, FLIP-344: Remove parameter in RichFunction#open

close

public void close()
           throws Exception

Description copied from interface: RichFunction

Tear-down method for the user code. It is called after the last call to the main working methods (e.g. map or join). For functions that are part of an iteration, this method will be invoked after each iteration superstep.

This method can be used for clean up work.

Specified by:

close in interface RichFunction

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.