org.apache.flink.streaming.api.functions.co.BroadcastProcessFunction Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.streaming.api.functions.co;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.state.MapStateDescriptor;
import org.apache.flink.util.Collector;
/**
* A function to be applied to a {@link
* org.apache.flink.streaming.api.datastream.BroadcastConnectedStream BroadcastConnectedStream} that
* connects {@link org.apache.flink.streaming.api.datastream.BroadcastStream BroadcastStream}, i.e.
* a stream with broadcast state, with a non-keyed {@link
* org.apache.flink.streaming.api.datastream.DataStream DataStream}.
*
* The stream with the broadcast state can be created using the {@link
* org.apache.flink.streaming.api.datastream.DataStream#broadcast(MapStateDescriptor[])}
* stream.broadcast(MapStateDescriptor)} method.
*
*
The user has to implement two methods:
*
*
* - the {@link #processBroadcastElement(Object, Context, Collector)} which will be applied to
* each element in the broadcast side
*
- and the {@link #processElement(Object, ReadOnlyContext, Collector)} which will be applied
* to the non-broadcasted/keyed side.
*
*
* The {@code processElementOnBroadcastSide()} takes as argument (among others) a context that
* allows it to read/write to the broadcast state, while the {@code processElement()} has read-only
* access to the broadcast state.
*
* @param The input type of the non-broadcast side.
* @param The input type of the broadcast side.
* @param The output type of the operator.
*/
@PublicEvolving
public abstract class BroadcastProcessFunction extends BaseBroadcastProcessFunction {
private static final long serialVersionUID = 8352559162119034453L;
/**
* This method is called for each element in the (non-broadcast) {@link
* org.apache.flink.streaming.api.datastream.DataStream data stream}.
*
* This function can output zero or more elements using the {@link Collector} parameter,
* query the current processing/event time, and also query and update the local keyed state.
* Finally, it has read-only access to the broadcast state. The context is only valid
* during the invocation of this method, do not store it.
*
* @param value The stream element.
* @param ctx A {@link ReadOnlyContext} that allows querying the timestamp of the element,
* querying the current processing/event time and updating the broadcast state. The context
* is only valid during the invocation of this method, do not store it.
* @param out The collector to emit resulting elements to
* @throws Exception The function may throw exceptions which cause the streaming program to fail
* and go into recovery.
*/
public abstract void processElement(
final IN1 value, final ReadOnlyContext ctx, final Collector out) throws Exception;
/**
* This method is called for each element in the {@link
* org.apache.flink.streaming.api.datastream.BroadcastStream broadcast stream}.
*
* This function can output zero or more elements using the {@link Collector} parameter,
* query the current processing/event time, and also query and update the internal {@link
* org.apache.flink.api.common.state.BroadcastState broadcast state}. These can be done through
* the provided {@link Context}. The context is only valid during the invocation of this method,
* do not store it.
*
* @param value The stream element.
* @param ctx A {@link Context} that allows querying the timestamp of the element, querying the
* current processing/event time and updating the broadcast state. The context is only valid
* during the invocation of this method, do not store it.
* @param out The collector to emit resulting elements to
* @throws Exception The function may throw exceptions which cause the streaming program to fail
* and go into recovery.
*/
public abstract void processBroadcastElement(
final IN2 value, final Context ctx, final Collector out) throws Exception;
/**
* A {@link BaseBroadcastProcessFunction.Context context} available to the broadcast side of a
* {@link org.apache.flink.streaming.api.datastream.BroadcastConnectedStream}.
*/
public abstract class Context extends BaseBroadcastProcessFunction.Context {}
/**
* A {@link BaseBroadcastProcessFunction.Context context} available to the non-keyed side of a
* {@link org.apache.flink.streaming.api.datastream.BroadcastConnectedStream} (if any).
*/
public abstract class ReadOnlyContext extends BaseBroadcastProcessFunction.ReadOnlyContext {}
}