org.apache.spark.sql.streaming.ValueState.scala Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of spark-sql-api_2.13 Show documentation

The newest version!

/*
 * 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.spark.sql.streaming

import java.io.Serializable

import org.apache.spark.annotation.{Evolving, Experimental}

@Experimental
@Evolving
/**
 * Interface used for arbitrary stateful operations with the v2 API to capture single value state.
 */
private[sql] trait ValueState[S] extends Serializable {

  /** Whether state exists or not. */
  def exists(): Boolean

  /**
   * Get the state value if it exists
   * @throws java.util.NoSuchElementException
   *   if the state does not exist
   */
  @throws[NoSuchElementException]
  def get(): S

  /** Get the state if it exists as an option and None otherwise */
  def getOption(): Option[S]

  /**
   * Update the value of the state.
   *
   * @param newState
   *   the new value
   */
  def update(newState: S): Unit

  /** Remove this state. */
  def clear(): Unit
}