Package org.apache.flink.table.runtime.operators.rank

Class FastTop1Function

java.lang.Object

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

org.apache.flink.streaming.api.functions.KeyedProcessFunction<RowData,RowData,RowData>

org.apache.flink.table.runtime.operators.rank.AbstractTopNFunction

org.apache.flink.table.runtime.operators.rank.FastTop1Function

All Implemented Interfaces:

Serializable, Function, RichFunction, CheckpointedFunction

public class FastTop1Function
extends AbstractTopNFunction
implements CheckpointedFunction

A more concise implementation for AppendOnlyTopNFunction and UpdatableTopNFunction when only Top-1 is desired. This function can handle updating stream because the RankProcessStrategy is inferred as UpdateFastStrategy, i.e., 1) the upsert key of input steam contains partition key; 2) the sort field is updated monotonely under the upsert key.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.functions.KeyedProcessFunction

KeyedProcessFunction.Context, KeyedProcessFunction.OnTimerContext

Field Summary

Fields inherited from class org.apache.flink.table.runtime.operators.rank.AbstractTopNFunction

hitCount, inputRowType, keyContext, outputRankNumber, rankEnd, requestCount, sortKeyComparator, sortKeySelector, ttlConfig

Constructor Summary

Constructors

Constructor	Description
FastTop1Function(StateTtlConfig ttlConfig, InternalTypeInfo<RowData> inputRowType, GeneratedRecordComparator generatedSortKeyComparator, RowDataKeySelector sortKeySelector, RankType rankType, RankRange rankRange, boolean generateUpdateBefore, boolean outputRankNumber, long cacheSize)

Method Summary

Modifier and Type	Method	Description
void	initializeState(FunctionInitializationContext context)	This method is called when the parallel function instance is created during distributed execution.
void	open(OpenContext openContext)	Initialization method for the function.
void	processElement(RowData input, KeyedProcessFunction.Context ctx, Collector<RowData> out)	Process one element from the input stream.
void	snapshotState(FunctionSnapshotContext context)	This method is called when a snapshot for a checkpoint is requested.

Methods inherited from class org.apache.flink.table.runtime.operators.rank.AbstractTopNFunction

checkSortKeyInBufferRange, collectDelete, collectDelete, collectInsert, collectInsert, collectUpdateAfter, collectUpdateAfter, collectUpdateBefore, collectUpdateBefore, getDefaultTopNSize, hasOffset, initRankEnd, isInRankEnd, isInRankRange, registerMetric, setKeyContext

Methods inherited from class org.apache.flink.streaming.api.functions.KeyedProcessFunction

onTimer

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

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

FastTop1Function

public FastTop1Function(StateTtlConfig ttlConfig,
                        InternalTypeInfo<RowData> inputRowType,
                        GeneratedRecordComparator generatedSortKeyComparator,
                        RowDataKeySelector sortKeySelector,
                        RankType rankType,
                        RankRange rankRange,
                        boolean generateUpdateBefore,
                        boolean outputRankNumber,
                        long cacheSize)

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);
     }
 }
 

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractTopNFunction

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.

processElement

public void processElement(RowData input,
                           KeyedProcessFunction.Context ctx,
                           Collector<RowData> out)
                    throws Exception

Description copied from class: KeyedProcessFunction

Process one element from the input stream.

This function can output zero or more elements using the Collector parameter and also update internal state or set timers using the KeyedProcessFunction.Context parameter.

Specified by:

processElement in class KeyedProcessFunction<RowData,RowData,RowData>

Parameters:

input - The input value.

ctx - A KeyedProcessFunction.Context that allows querying the timestamp of the element and getting a TimerService for registering timers and querying the time. The context is only valid during the invocation of this method, do not store it.

out - The collector for returning result values.

Throws:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.

snapshotState

public void snapshotState(FunctionSnapshotContext context)
                   throws Exception

Description copied from interface: CheckpointedFunction

This method is called when a snapshot for a checkpoint is requested. This acts as a hook to the function to ensure that all state is exposed by means previously offered through FunctionInitializationContext when the Function was initialized, or offered now by FunctionSnapshotContext itself.

Specified by:

snapshotState in interface CheckpointedFunction

Parameters:

context - the context for drawing a snapshot of the operator

Throws:

Exception - Thrown, if state could not be created ot restored.

initializeState

public void initializeState(FunctionInitializationContext context)
                     throws Exception

Description copied from interface: CheckpointedFunction

This method is called when the parallel function instance is created during distributed execution. Functions typically set up their state storing data structures in this method.

Specified by:

initializeState in interface CheckpointedFunction

Parameters:

context - the context for initializing the operator

Throws:

Exception - Thrown, if state could not be created ot restored.