diff options
Diffstat (limited to 'core/src/main')
5 files changed, 191 insertions, 12 deletions
diff --git a/core/src/main/java/org/apache/spark/api/java/Optional.java b/core/src/main/java/org/apache/spark/api/java/Optional.java new file mode 100644 index 0000000000..ca7babc3f0 --- /dev/null +++ b/core/src/main/java/org/apache/spark/api/java/Optional.java @@ -0,0 +1,187 @@ +/* + * 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.api.java; + +import java.io.Serializable; + +import com.google.common.base.Preconditions; + +/** + * <p>Like {@code java.util.Optional} in Java 8, {@code scala.Option} in Scala, and + * {@code com.google.common.base.Optional} in Google Guava, this class represents a + * value of a given type that may or may not exist. It is used in methods that wish + * to optionally return a value, in preference to returning {@code null}.</p> + * + * <p>In fact, the class here is a reimplementation of the essential API of both + * {@code java.util.Optional} and {@code com.google.common.base.Optional}. From + * {@code java.util.Optional}, it implements:</p> + * + * <ul> + * <li>{@link #empty()}</li> + * <li>{@link #of(Object)}</li> + * <li>{@link #ofNullable(Object)}</li> + * <li>{@link #get()}</li> + * <li>{@link #orElse(Object)}</li> + * <li>{@link #isPresent()}</li> + * </ul> + * + * <p>From {@code com.google.common.base.Optional} it implements:</p> + * + * <ul> + * <li>{@link #absent()}</li> + * <li>{@link #of(Object)}</li> + * <li>{@link #fromNullable(Object)}</li> + * <li>{@link #get()}</li> + * <li>{@link #or(Object)}</li> + * <li>{@link #orNull()}</li> + * <li>{@link #isPresent()}</li> + * </ul> + * + * <p>{@code java.util.Optional} itself is not used at this time because the + * project does not require Java 8. Using {@code com.google.common.base.Optional} + * has in the past caused serious library version conflicts with Guava that can't + * be resolved by shading. Hence this work-alike clone.</p> + * + * @param <T> type of value held inside + */ +public final class Optional<T> implements Serializable { + + private static final Optional<?> EMPTY = new Optional<>(); + + private final T value; + + private Optional() { + this.value = null; + } + + private Optional(T value) { + Preconditions.checkNotNull(value); + this.value = value; + } + + // java.util.Optional API (subset) + + /** + * @return an empty {@code Optional} + */ + public static <T> Optional<T> empty() { + @SuppressWarnings("unchecked") + Optional<T> t = (Optional<T>) EMPTY; + return t; + } + + /** + * @param value non-null value to wrap + * @return {@code Optional} wrapping this value + * @throws NullPointerException if value is null + */ + public static <T> Optional<T> of(T value) { + return new Optional<>(value); + } + + /** + * @param value value to wrap, which may be null + * @return {@code Optional} wrapping this value, which may be empty + */ + public static <T> Optional<T> ofNullable(T value) { + if (value == null) { + return empty(); + } else { + return of(value); + } + } + + /** + * @return the value wrapped by this {@code Optional} + * @throws NullPointerException if this is empty (contains no value) + */ + public T get() { + Preconditions.checkNotNull(value); + return value; + } + + /** + * @param other value to return if this is empty + * @return this {@code Optional}'s value if present, or else the given value + */ + public T orElse(T other) { + return value != null ? value : other; + } + + /** + * @return true iff this {@code Optional} contains a value (non-empty) + */ + public boolean isPresent() { + return value != null; + } + + // Guava API (subset) + // of(), get() and isPresent() are identically present in the Guava API + + /** + * @return an empty {@code Optional} + */ + public static <T> Optional<T> absent() { + return empty(); + } + + /** + * @param value value to wrap, which may be null + * @return {@code Optional} wrapping this value, which may be empty + */ + public static <T> Optional<T> fromNullable(T value) { + return ofNullable(value); + } + + /** + * @param other value to return if this is empty + * @return this {@code Optional}'s value if present, or else the given value + */ + public T or(T other) { + return value != null ? value : other; + } + + /** + * @return this {@code Optional}'s value if present, or else null + */ + public T orNull() { + return value; + } + + // Common methods + + @Override + public boolean equals(Object obj) { + if (!(obj instanceof Optional)) { + return false; + } + Optional<?> other = (Optional<?>) obj; + return value == null ? other.value == null : value.equals(other.value); + } + + @Override + public int hashCode() { + return value == null ? 0 : value.hashCode(); + } + + @Override + public String toString() { + return value == null ? "Optional.empty" : String.format("Optional[%s]", value); + } + +} diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala index 59af1052eb..fb04472ee7 100644 --- a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala +++ b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala @@ -25,7 +25,6 @@ import scala.collection.JavaConverters._ import scala.language.implicitConversions import scala.reflect.ClassTag -import com.google.common.base.Optional import org.apache.hadoop.conf.Configuration import org.apache.hadoop.io.compress.CompressionCodec import org.apache.hadoop.mapred.{JobConf, OutputFormat} @@ -655,7 +654,6 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)]) * keys; this also retains the original RDD's partitioning. */ def flatMapValues[U](f: JFunction[V, java.lang.Iterable[U]]): JavaPairRDD[K, U] = { - import scala.collection.JavaConverters._ def fn: (V) => Iterable[U] = (x: V) => f.call(x).asScala implicit val ctag: ClassTag[U] = fakeClassTag fromRDD(rdd.flatMapValues(fn)) diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala index 242438237f..0f8d13cf5c 100644 --- a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala +++ b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala @@ -24,7 +24,6 @@ import java.util.{Comparator, Iterator => JIterator, List => JList} import scala.collection.JavaConverters._ import scala.reflect.ClassTag -import com.google.common.base.Optional import org.apache.hadoop.io.compress.CompressionCodec import org.apache.spark._ @@ -122,7 +121,6 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable { * RDD, and then flattening the results. */ def flatMap[U](f: FlatMapFunction[T, U]): JavaRDD[U] = { - import scala.collection.JavaConverters._ def fn: (T) => Iterable[U] = (x: T) => f.call(x).asScala JavaRDD.fromRDD(rdd.flatMap(fn)(fakeClassTag[U]))(fakeClassTag[U]) } @@ -132,7 +130,6 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable { * RDD, and then flattening the results. */ def flatMapToDouble(f: DoubleFlatMapFunction[T]): JavaDoubleRDD = { - import scala.collection.JavaConverters._ def fn: (T) => Iterable[jl.Double] = (x: T) => f.call(x).asScala new JavaDoubleRDD(rdd.flatMap(fn).map((x: jl.Double) => x.doubleValue())) } @@ -142,7 +139,6 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable { * RDD, and then flattening the results. */ def flatMapToPair[K2, V2](f: PairFlatMapFunction[T, K2, V2]): JavaPairRDD[K2, V2] = { - import scala.collection.JavaConverters._ def fn: (T) => Iterable[(K2, V2)] = (x: T) => f.call(x).asScala def cm: ClassTag[(K2, V2)] = implicitly[ClassTag[(K2, V2)]] JavaPairRDD.fromRDD(rdd.flatMap(fn)(cm))(fakeClassTag[K2], fakeClassTag[V2]) diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala index 9990b22e14..01433ca2ef 100644 --- a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala +++ b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala @@ -25,7 +25,6 @@ import scala.collection.JavaConverters._ import scala.language.implicitConversions import scala.reflect.ClassTag -import com.google.common.base.Optional import org.apache.hadoop.conf.Configuration import org.apache.hadoop.mapred.{InputFormat, JobConf} import org.apache.hadoop.mapreduce.{InputFormat => NewInputFormat} diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala b/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala index b2a4d053fa..f820401da2 100644 --- a/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala +++ b/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala @@ -22,13 +22,12 @@ import java.util.Map.Entry import scala.collection.mutable -import com.google.common.base.Optional - private[spark] object JavaUtils { def optionToOptional[T](option: Option[T]): Optional[T] = - option match { - case Some(value) => Optional.of(value) - case None => Optional.absent() + if (option.isDefined) { + Optional.of(option.get) + } else { + Optional.empty[T] } // Workaround for SPARK-3926 / SI-8911 |