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ASF GitHub Bot commented on FLINK-7206: --------------------------------------- Github user wuchong commented on a diff in the pull request: https://github.com/apache/flink/pull/4355#discussion_r134118744 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/dataview/MapView.scala --- @@ -0,0 +1,192 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * 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.table.api.dataview + +import java.lang.{Iterable => JIterable} +import java.util + +import org.apache.flink.api.common.typeinfo.{TypeInfo, TypeInformation} +import org.apache.flink.table.dataview.MapViewTypeInfoFactory + +/** + * MapView provides Map functionality for accumulators used by user-defined aggregate functions + * [[org.apache.flink.table.functions.AggregateFunction]]. + * + * A MapView can be backed by a Java HashMap or a state backend, depending on the context in + * which the function is used. + * + * At runtime `MapView` will be replaced by a [[org.apache.flink.table.dataview.StateMapView]] + * when use state backend. + * + * Example: + * {{{ + * + * public class MyAccum { + * public MapView<String, Integer> map; + * public long count; + * } + * + * public class MyAgg extends AggregateFunction<Long, MyAccum> { + * + * @Override + * public MyAccum createAccumulator() { + * MyAccum accum = new MyAccum(); + * accum.map = new MapView<>(Types.STRING, Types.INT); + * accum.count = 0L; + * return accum; + * } + * + * public void accumulate(MyAccum accumulator, String id) { + * try { + * if (!accumulator.map.contains(id)) { + * accumulator.map.put(id, 1); + * accumulator.count++; + * } + * } catch (Exception e) { + * e.printStackTrace(); + * } + * } + * + * @Override + * public Long getValue(MyAccum accumulator) { + * return accumulator.count; + * } + * } + * + * }}} + * + * @param keyTypeInfo key type information + * @param valueTypeInfo value type information + * @tparam K key type + * @tparam V value type + */ +@TypeInfo(classOf[MapViewTypeInfoFactory[_, _]]) +class MapView[K, V]( + private[flink] val keyTypeInfo: TypeInformation[K], + private[flink] val valueTypeInfo: TypeInformation[V]) + extends DataView { + + def this() = this(null, null) + + val map = new util.HashMap[K, V]() --- End diff -- please make the `map` private > Implementation of DataView to support state access for UDAGG > ------------------------------------------------------------ > > Key: FLINK-7206 > URL: https://issues.apache.org/jira/browse/FLINK-7206 > Project: Flink > Issue Type: Sub-task > Components: Table API & SQL > Reporter: Kaibo Zhou > Assignee: Kaibo Zhou > > Implementation of MapView and ListView to support state access for UDAGG. -- This message was sent by Atlassian JIRA (v6.4.14#64029)