org.apache.flink.state.api.input.operator.window

Class EvictingWindowReaderFunction<IN,R,OUT,KEY,W extends Window>

java.lang.Object

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

org.apache.flink.state.api.functions.WindowReaderFunction<StreamRecord<IN>,OUT,KEY,W>

org.apache.flink.state.api.input.operator.window.EvictingWindowReaderFunction<IN,R,OUT,KEY,W>

Type Parameters:

IN - The input type stored in state.

R - The aggregated type.

OUT - The output type of the reader function.

KEY - The key type.

W - The window type.

All Implemented Interfaces:

Serializable, Function, RichFunction

Direct Known Subclasses:

AggregateEvictingWindowReaderFunction, ProcessEvictingWindowReader, ReduceEvictingWindowReaderFunction

@Internal
public abstract class EvictingWindowReaderFunction<IN,R,OUT,KEY,W extends Window>
extends WindowReaderFunction<StreamRecord<IN>,OUT,KEY,W>

Wrapper for reading state from an evicting window operator.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.state.api.functions.WindowReaderFunction

WindowReaderFunction.Context<W extends Window>

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	EvictingWindowReaderFunction(WindowReaderFunction<R,OUT,KEY,W> wrappedFunction)

Method Summary

Modifier and Type	Method and Description
void	close() Tear-down method for the user code.
void	open(OpenContext openContext) Initialization method for the function.
void	readWindow(KEY key, WindowReaderFunction.Context<W> context, Iterable<StreamRecord<IN>> elements, Collector<OUT> out) Evaluates the window and outputs none or several elements.
void	setRuntimeContext(RuntimeContext t) Sets the function's runtime context.
abstract Iterable<R>	transform(Iterable<StreamRecord<IN>> elements)

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

getIterationRuntimeContext, getRuntimeContext, open

Methods inherited from class java.lang.Object

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

Constructor Detail

EvictingWindowReaderFunction

protected EvictingWindowReaderFunction(WindowReaderFunction<R,OUT,KEY,W> wrappedFunction)

Method Detail

open

public void open(OpenContext openContext)
          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 openContext object passed to the function can be used for configuration and initialization. The openContext contains some necessary information that were configured on the function in the program composition.

 public class MyFilter extends RichFilterFunction<String> {

     private String searchString;

     public void open(OpenContext openContext) {
         // initialize the value of searchString
     }

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

By default, this method does nothing.

1. If you implement open(OpenContext openContext), the open(OpenContext openContext) will be invoked and the open(Configuration parameters) won't be invoked. 2. If you don't implement open(OpenContext openContext), the open(Configuration parameters) will be invoked in the default implementation of the open(OpenContext openContext).

Parameters:

openContext - The context containing information about the context in which the function is opened.

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.

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

Overrides:

close in class AbstractRichFunction

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.

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

Overrides:

setRuntimeContext in class AbstractRichFunction

Parameters:

t - The runtime context.

readWindow

public void readWindow(KEY key,
                       WindowReaderFunction.Context<W> context,
                       Iterable<StreamRecord<IN>> elements,
                       Collector<OUT> out)
                throws Exception

Description copied from class: WindowReaderFunction

Evaluates the window and outputs none or several elements.

Specified by:

readWindow in class WindowReaderFunction<StreamRecord<IN>,OUT,KEY,W extends Window>

Parameters:

key - The key for which this window is evaluated.

context - The context in which the window is being evaluated.

elements - The elements in the window being evaluated.

out - A collector for emitting elements.

Throws:

Exception - The function may throw exceptions to fail the program and trigger recovery.

transform

public abstract Iterable<R> transform(Iterable<StreamRecord<IN>> elements)
                               throws Exception

Throws:

Exception