[
https://issues.apache.org/jira/browse/BEAM-7013?focusedWorklogId=293270&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-293270
]
ASF GitHub Bot logged work on BEAM-7013:
----------------------------------------
Author: ASF GitHub Bot
Created on: 12/Aug/19 17:09
Start Date: 12/Aug/19 17:09
Worklog Time Spent: 10m
Work Description: zfraa commented on pull request #9144: [BEAM-7013]
Integrating ZetaSketch's HLL++ algorithm with Beam
URL: https://github.com/apache/beam/pull/9144#discussion_r312973419
##########
File path:
sdks/java/extensions/zetasketch/src/main/java/org/apache/beam/sdk/extensions/zetasketch/HllCountMergePartialFn.java
##########
@@ -0,0 +1,151 @@
+/*
+ * 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.sdk.extensions.zetasketch;
+
+import com.google.zetasketch.HyperLogLogPlusPlus;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import javax.annotation.Nullable;
+import org.apache.beam.sdk.coders.AtomicCoder;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.beam.sdk.coders.NullableCoder;
+import
org.apache.beam.sdk.extensions.zetasketch.HllCountMergePartialFn.HyperLogLogPlusPlusWrapper;
+import org.apache.beam.sdk.transforms.Combine;
+
+/**
+ * {@link Combine.CombineFn} for the {@link HllCount.MergePartial} combiner.
+ *
+ * @param <T> type of the HLL++ sketch to be merged
+ */
+class HllCountMergePartialFn<T>
+ extends Combine.CombineFn<byte[], HyperLogLogPlusPlusWrapper<T>, byte[]> {
+
+ // Call HllCountMergePartialFn.create() to instantiate
+ private HllCountMergePartialFn() {}
+
+ static HllCountMergePartialFn<?> create() {
+ return new HllCountMergePartialFn();
+ }
+
+ /**
+ * Accumulator for the {@link HllCount.MergePartial} combiner. Cannot use
{@link
+ * HyperLogLogPlusPlus} directly because we need an "identity element" for
the {@code merge}
+ * operation, and we are not able to create such "identity element" of type
{@link
+ * HyperLogLogPlusPlus} without knowing the sketch precision and value type.
+ */
+ static final class HyperLogLogPlusPlusWrapper<T> {
+ @Nullable private HyperLogLogPlusPlus<T> hll;
+
+ private HyperLogLogPlusPlusWrapper(@Nullable HyperLogLogPlusPlus<T> hll) {
+ this.hll = hll;
+ }
+ }
+
+ /**
+ * Coder for the {@link HyperLogLogPlusPlusWrapper} class with generic type
parameter {@code T}.
+ */
+ private static final class HyperLogLogPlusPlusWrapperCoder<T>
+ extends AtomicCoder<HyperLogLogPlusPlusWrapper<T>> {
+
+ private static final HyperLogLogPlusPlusWrapperCoder<?> INSTANCE =
+ new HyperLogLogPlusPlusWrapperCoder<>();
+
+ private final Coder<HyperLogLogPlusPlus<T>> nullableHllCoder =
+ NullableCoder.of(HyperLogLogPlusPlusCoder.of());
+
+ // Generic singleton factory pattern; the coder works for all
HyperLogLogPlusPlusWrapper objects
+ // at runtime regardless of type T
+ @SuppressWarnings("unchecked")
+ static <T> HyperLogLogPlusPlusWrapperCoder<T> of() {
+ return (HyperLogLogPlusPlusWrapperCoder<T>) INSTANCE;
+ }
+
+ @Override
+ public void encode(HyperLogLogPlusPlusWrapper<T> value, OutputStream
outStream)
+ throws IOException {
+ nullableHllCoder.encode(value.hll, outStream);
+ }
+
+ @Override
+ public HyperLogLogPlusPlusWrapper<T> decode(InputStream inStream) throws
IOException {
+ return new
HyperLogLogPlusPlusWrapper<T>(nullableHllCoder.decode(inStream));
+ }
+
+ @Override
+ public void verifyDeterministic() throws NonDeterministicException {
+ nullableHllCoder.verifyDeterministic();
+ }
+ }
+
+ @Override
+ public Coder<HyperLogLogPlusPlusWrapper<T>> getAccumulatorCoder(
+ CoderRegistry registry, Coder<byte[]> inputCoder) {
+ return HyperLogLogPlusPlusWrapperCoder.of();
+ }
+
+ @Override
+ public HyperLogLogPlusPlusWrapper<T> createAccumulator() {
+ return new HyperLogLogPlusPlusWrapper<>(null);
+ }
+
+ @Override
+ public HyperLogLogPlusPlusWrapper<T> addInput(
+ HyperLogLogPlusPlusWrapper<T> accumulator, byte[] input) {
+ if (accumulator.hll == null) {
Review comment:
[if we stick with the wrapper:] I would encapsulate this functionality with
the wrapper - add a 'addInput" method to the wrapper and check there whether
the internal field is null, etc. Or do you prefer this current version because
it's one indirection less?
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Issue Time Tracking
-------------------
Worklog Id: (was: 293270)
> A new count distinct transform based on BigQuery compatible HyperLogLog++
> implementation
> ----------------------------------------------------------------------------------------
>
> Key: BEAM-7013
> URL: https://issues.apache.org/jira/browse/BEAM-7013
> Project: Beam
> Issue Type: New Feature
> Components: extensions-java-sketching, sdk-java-core
> Reporter: Yueyang Qiu
> Assignee: Yueyang Qiu
> Priority: Major
> Fix For: 2.16.0
>
> Time Spent: 12h 40m
> Remaining Estimate: 0h
>
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