public class UpdatableTopNFunction extends AbstractTopNFunction implements CheckpointedFunction
RetractableTopNFunction which only hold top n data in state, and keep sorted map in heap.
However, the function only works in some special scenarios: 1. sort field collation is ascending
and its mono is decreasing, or sort field collation is descending and its mono is increasing 2.
input data has unique keys and unique key must contain partition key 3. input stream could not
contain DELETE record or UPDATE_BEFORE recordKeyedProcessFunction.Context, KeyedProcessFunction.OnTimerContexthitCount, inputRowType, keyContext, outputRankNumber, rankEnd, requestCount, sortKeyComparator, sortKeySelector, ttlConfig| Constructor and Description |
|---|
UpdatableTopNFunction(StateTtlConfig ttlConfig,
InternalTypeInfo<RowData> inputRowType,
RowDataKeySelector rowKeySelector,
GeneratedRecordComparator generatedRecordComparator,
RowDataKeySelector sortKeySelector,
RankType rankType,
RankRange rankRange,
boolean generateUpdateBefore,
boolean outputRankNumber,
long cacheSize) |
| Modifier and Type | Method and 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 context,
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.
|
checkSortKeyInBufferRange, collectDelete, collectDelete, collectInsert, collectInsert, collectUpdateAfter, collectUpdateAfter, collectUpdateBefore, collectUpdateBefore, getDefaultTopNSize, hasOffset, initRankEnd, isInRankEnd, isInRankRange, registerMetric, setKeyContextonTimerclose, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContextpublic UpdatableTopNFunction(StateTtlConfig ttlConfig, InternalTypeInfo<RowData> inputRowType, RowDataKeySelector rowKeySelector, GeneratedRecordComparator generatedRecordComparator, RowDataKeySelector sortKeySelector, RankType rankType, RankRange rankRange, boolean generateUpdateBefore, boolean outputRankNumber, long cacheSize)
public void open(OpenContext openContext) throws Exception
RichFunctionThe 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).
open in interface RichFunctionopen in class AbstractTopNFunctionopenContext - The context containing information about the context in which the function
is opened.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.public void initializeState(FunctionInitializationContext context) throws Exception
CheckpointedFunctioninitializeState in interface CheckpointedFunctioncontext - the context for initializing the operatorException - Thrown, if state could not be created ot restored.public void processElement(RowData input, KeyedProcessFunction.Context context, Collector<RowData> out) throws Exception
KeyedProcessFunctionThis function can output zero or more elements using the Collector parameter and
also update internal state or set timers using the KeyedProcessFunction.Context parameter.
processElement in class KeyedProcessFunction<RowData,RowData,RowData>input - The input value.context - 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.Exception - This method may throw exceptions. Throwing an exception will cause the
operation to fail and may trigger recovery.public void snapshotState(FunctionSnapshotContext context) throws Exception
CheckpointedFunctionFunctionInitializationContext when the Function was initialized, or offered now by FunctionSnapshotContext itself.snapshotState in interface CheckpointedFunctioncontext - the context for drawing a snapshot of the operatorException - Thrown, if state could not be created ot restored.Copyright © 2014–2024 The Apache Software Foundation. All rights reserved.