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From fhueske <...@git.apache.org>
Subject [GitHub] flink pull request #4355: [FLINK-7206] [table] Implementation of DataView to...
Date Thu, 24 Aug 2017 21:54:38 GMT
Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4355#discussion_r135107609
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/dataview/MapView.scala
---
    @@ -0,0 +1,188 @@
    +/*
    + * 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](
    +    @transient private[flink] val keyTypeInfo: TypeInformation[K],
    +    @transient private[flink] val valueTypeInfo: TypeInformation[V])
    +  extends DataView {
    +
    +  def this() = this(null, null)
    +
    +  private[flink] var map = new util.HashMap[K, V]()
    +
    +  /**
    +    * Returns the value to which the specified key is mapped, or { @code null } if this
map
    +    * contains no mapping for the key.
    +    *
    +    * @param key The key of the mapping.
    +    * @return The value of the mapping with the given key.
    +    * @throws Exception Thrown if the system cannot get data.
    +    */
    +  @throws[Exception]
    +  def get(key: K): V = map.get(key)
    +
    +  /**
    +    * Put a value with the given key into the map.
    +    *
    +    * @param key   The key of the mapping.
    +    * @param value The new value of the mapping.
    +    * @throws Exception Thrown if the system cannot put data.
    +    */
    +  @throws[Exception]
    +  def put(key: K, value: V): Unit = map.put(key, value)
    +
    +  /**
    +    * Copies all of the mappings from the specified map to this map view.
    +    *
    +    * @param map The mappings to be stored in this map.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def putAll(map: util.Map[K, V]): Unit = this.map.putAll(map)
    +
    +  /**
    +    * Deletes the mapping of the given key.
    +    *
    +    * @param key The key of the mapping.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def remove(key: K): Unit = map.remove(key)
    +
    +  /**
    +    * Returns whether there exists the given mapping.
    +    *
    +    * @param key The key of the mapping.
    +    * @return True if there exists a mapping whose key equals to the given key.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def contains(key: K): Boolean = map.containsKey(key)
    +
    +  /**
    +    * Returns all the mappings in the map.
    +    *
    +    * @return An iterable view of all the key-value pairs in the map.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def entries: JIterable[util.Map.Entry[K, V]] = map.entrySet()
    +
    +  /**
    +    * Returns all the keys in the map.
    +    *
    +    * @return An iterable view of all the keys in the map.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def keys: JIterable[K] = map.keySet()
    +
    +  /**
    +    * Returns all the values in the map.
    +    *
    +    * @return An iterable view of all the values in the map.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def values: JIterable[V] = map.values()
    +
    +  /**
    +    * Iterates over all the mappings in the map.
    +    *
    +    * @return An iterator over all the mappings in the map.
    +    * @throws Exception Thrown if the system cannot access the map.
    +    */
    +  @throws[Exception]
    +  def iterator: util.Iterator[util.Map.Entry[K, V]] = map.entrySet().iterator()
    +
    +  /**
    +    * Removes all of the mappings from this map (optional operation).
    +    *
    +    * The map will be empty after this call returns.
    +    */
    +  override def clear(): Unit = map.clear()
    +
    +  override def equals(other: Any): Boolean = other match {
    +    case that: MapView[_, _] =>
    --- End diff --
    
    `case that: MapView[K, V] =>` ?


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