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[BEAM-5392] GroupByKey optimized for non-merging windows
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242
.../main/java/org/apache/beam/runners/spark/translation/GroupNonMergingWindowsFunctions.java
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| /* | ||
| * 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.beam.runners.spark.translation; | ||
|
|
||
| import java.io.Serializable; | ||
| import java.util.Arrays; | ||
| import java.util.Iterator; | ||
| import java.util.Objects; | ||
| import org.apache.beam.runners.spark.coders.CoderHelpers; | ||
| import org.apache.beam.sdk.coders.ByteArrayCoder; | ||
| import org.apache.beam.sdk.coders.Coder; | ||
| import org.apache.beam.sdk.transforms.windowing.BoundedWindow; | ||
| import org.apache.beam.sdk.util.WindowedValue; | ||
| import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder; | ||
| import org.apache.beam.sdk.values.KV; | ||
| import org.apache.beam.sdk.values.WindowingStrategy; | ||
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.AbstractIterator; | ||
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Iterables; | ||
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Iterators; | ||
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.PeekingIterator; | ||
| import org.apache.beam.vendor.guava.v20_0.com.google.common.primitives.UnsignedBytes; | ||
| import org.apache.spark.HashPartitioner; | ||
| import org.apache.spark.api.java.JavaRDD; | ||
| import org.joda.time.Instant; | ||
| import scala.Tuple2; | ||
|
|
||
| /** Functions for GroupByKey with Non-Merging windows translations to Spark. */ | ||
| public class GroupNonMergingWindowsFunctions { | ||
|
|
||
| static <K, V, W extends BoundedWindow> | ||
| JavaRDD<WindowedValue<KV<K, Iterable<V>>>> groupByKeyAndWindow( | ||
| JavaRDD<WindowedValue<KV<K, V>>> rdd, | ||
| Coder<K> keyCoder, | ||
| Coder<V> valueCoder, | ||
| WindowingStrategy<?, W> windowingStrategy) { | ||
| final Coder<W> windowCoder = windowingStrategy.getWindowFn().windowCoder(); | ||
| final WindowedValue.FullWindowedValueCoder<byte[]> windowedValueCoder = | ||
| WindowedValue.getFullCoder(ByteArrayCoder.of(), windowCoder); | ||
| return rdd.flatMapToPair( | ||
| (WindowedValue<KV<K, V>> windowedValue) -> { | ||
| final byte[] keyBytes = | ||
| CoderHelpers.toByteArray(windowedValue.getValue().getKey(), keyCoder); | ||
| final byte[] valueBytes = | ||
| CoderHelpers.toByteArray(windowedValue.getValue().getValue(), valueCoder); | ||
| return Iterators.transform( | ||
| windowedValue.explodeWindows().iterator(), | ||
| item -> { | ||
| Objects.requireNonNull(item, "Exploded window can not be null."); | ||
| @SuppressWarnings("unchecked") | ||
| final W window = (W) Iterables.getOnlyElement(item.getWindows()); | ||
| final byte[] windowBytes = CoderHelpers.toByteArray(window, windowCoder); | ||
| final byte[] windowValueBytes = | ||
| CoderHelpers.toByteArray( | ||
| WindowedValue.of( | ||
| valueBytes, item.getTimestamp(), window, item.getPane()), | ||
| windowedValueCoder); | ||
| final WindowedKey windowedKey = new WindowedKey(keyBytes, windowBytes); | ||
| return new Tuple2<>(windowedKey, windowValueBytes); | ||
| }); | ||
| }) | ||
| .repartitionAndSortWithinPartitions(new HashPartitioner(rdd.getNumPartitions())) | ||
| .mapPartitions( | ||
| it -> | ||
| new GroupByKeyIterator<>( | ||
| it, keyCoder, valueCoder, windowingStrategy, windowedValueCoder)) | ||
| .filter(Objects::nonNull); // filter last null element from GroupByKeyIterator | ||
| } | ||
|
|
||
| /** | ||
| * Transform stream of sorted key values into stream of value iterators for each key. This | ||
| * iterator can be iterated only once! | ||
| * | ||
| * @param <K> type of key iterator emits | ||
| * @param <V> type of value iterator emits | ||
| */ | ||
| static class GroupByKeyIterator<K, V, W extends BoundedWindow> | ||
| implements Iterator<WindowedValue<KV<K, Iterable<V>>>> { | ||
|
|
||
| private final PeekingIterator<Tuple2<WindowedKey, byte[]>> inner; | ||
| private final Coder<K> keyCoder; | ||
| private final Coder<V> valueCoder; | ||
| private final WindowingStrategy<?, W> windowingStrategy; | ||
| private final FullWindowedValueCoder<byte[]> windowedValueCoder; | ||
| private boolean hasNext = true; | ||
|
|
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| private WindowedKey currentKey = null; | ||
|
|
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| GroupByKeyIterator( | ||
| Iterator<Tuple2<WindowedKey, byte[]>> inner, | ||
| Coder<K> keyCoder, | ||
| Coder<V> valueCoder, | ||
| WindowingStrategy<?, W> windowingStrategy, | ||
| WindowedValue.FullWindowedValueCoder<byte[]> windowedValueCoder) { | ||
| this.inner = Iterators.peekingIterator(inner); | ||
| this.keyCoder = keyCoder; | ||
| this.valueCoder = valueCoder; | ||
| this.windowingStrategy = windowingStrategy; | ||
| this.windowedValueCoder = windowedValueCoder; | ||
| } | ||
|
|
||
| @Override | ||
| public boolean hasNext() { | ||
| return hasNext; | ||
| } | ||
|
|
||
| @Override | ||
| public WindowedValue<KV<K, Iterable<V>>> next() { | ||
| while (inner.hasNext()) { | ||
| final WindowedKey nextKey = inner.peek()._1; | ||
| if (nextKey.equals(currentKey)) { | ||
| // we still did not see all values for a given key | ||
| inner.next(); | ||
| continue; | ||
| } | ||
| currentKey = nextKey; | ||
| final WindowedValue<KV<K, V>> decodedItem = decodeItem(inner.peek()); | ||
| return decodedItem.withValue( | ||
| KV.of(decodedItem.getValue().getKey(), new ValueIterator(inner, currentKey))); | ||
| } | ||
| hasNext = false; | ||
| return null; | ||
| } | ||
|
|
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| class ValueIterator implements Iterable<V> { | ||
|
|
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| boolean usedAsIterable = false; | ||
| private final PeekingIterator<Tuple2<WindowedKey, byte[]>> inner; | ||
| private WindowedKey currentKey; | ||
|
|
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| ValueIterator(PeekingIterator<Tuple2<WindowedKey, byte[]>> inner, WindowedKey currentKey) { | ||
| this.inner = inner; | ||
| this.currentKey = currentKey; | ||
| } | ||
|
|
||
| @Override | ||
| public Iterator<V> iterator() { | ||
| if (usedAsIterable) { | ||
| throw new IllegalStateException( | ||
| "ValueIterator can't be iterated more than once," | ||
| + "otherwise there could be data lost"); | ||
| } | ||
| usedAsIterable = true; | ||
| return new AbstractIterator<V>() { | ||
| @Override | ||
| protected V computeNext() { | ||
| if (inner.hasNext() && currentKey.equals(inner.peek()._1)) { | ||
| return decodeValue(inner.next()._2); | ||
| } | ||
| return endOfData(); | ||
| } | ||
| }; | ||
| } | ||
| } | ||
|
|
||
| private V decodeValue(byte[] windowedValueBytes) { | ||
| final WindowedValue<byte[]> windowedValue = | ||
| CoderHelpers.fromByteArray(windowedValueBytes, windowedValueCoder); | ||
| return CoderHelpers.fromByteArray(windowedValue.getValue(), valueCoder); | ||
| } | ||
|
|
||
| private WindowedValue<KV<K, V>> decodeItem(Tuple2<WindowedKey, byte[]> item) { | ||
| final K key = CoderHelpers.fromByteArray(item._1.getKey(), keyCoder); | ||
| final WindowedValue<byte[]> windowedValue = | ||
| CoderHelpers.fromByteArray(item._2, windowedValueCoder); | ||
| final V value = CoderHelpers.fromByteArray(windowedValue.getValue(), valueCoder); | ||
| @SuppressWarnings("unchecked") | ||
| final W window = (W) Iterables.getOnlyElement(windowedValue.getWindows()); | ||
| final Instant timestamp = | ||
| windowingStrategy | ||
| .getTimestampCombiner() | ||
| .assign( | ||
| window, | ||
| windowingStrategy | ||
| .getWindowFn() | ||
| .getOutputTime(windowedValue.getTimestamp(), window)); | ||
| return WindowedValue.of(KV.of(key, value), timestamp, window, windowedValue.getPane()); | ||
| } | ||
| } | ||
|
|
||
| /** Composite key of key and window for groupByKey transformation. */ | ||
| public static class WindowedKey implements Comparable<WindowedKey>, Serializable { | ||
|
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| private final byte[] key; | ||
| private final byte[] window; | ||
|
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| WindowedKey(byte[] key, byte[] window) { | ||
| this.key = key; | ||
| this.window = window; | ||
| } | ||
|
|
||
| @Override | ||
| public boolean equals(Object o) { | ||
| if (this == o) { | ||
| return true; | ||
| } | ||
| if (o == null || getClass() != o.getClass()) { | ||
| return false; | ||
| } | ||
| WindowedKey that = (WindowedKey) o; | ||
| return Arrays.equals(key, that.key) && Arrays.equals(window, that.window); | ||
| } | ||
|
|
||
| @Override | ||
| public int hashCode() { | ||
| int result = Arrays.hashCode(key); | ||
| result = 31 * result + Arrays.hashCode(window); | ||
| return result; | ||
| } | ||
|
|
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| public byte[] getKey() { | ||
| return key; | ||
| } | ||
|
|
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| public byte[] getWindow() { | ||
| return window; | ||
| } | ||
|
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| @Override | ||
| public int compareTo(WindowedKey o) { | ||
| int keyCompare = UnsignedBytes.lexicographicalComparator().compare(this.getKey(), o.getKey()); | ||
| if (keyCompare == 0) { | ||
| return UnsignedBytes.lexicographicalComparator().compare(this.getWindow(), o.getWindow()); | ||
| } | ||
| return keyCompare; | ||
| } | ||
| } | ||
| } |
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