lukecwik commented on a change in pull request #11715: URL: https://github.com/apache/beam/pull/11715#discussion_r427400011
########## File path: sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTrackerTest.java ########## @@ -0,0 +1,231 @@ +/* + * 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.transforms.splittabledofn; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertNull; +import static org.junit.Assert.assertTrue; + +import org.apache.beam.sdk.io.range.OffsetRange; +import org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker.Progress; +import org.junit.Rule; +import org.junit.Test; +import org.junit.rules.ExpectedException; +import org.junit.runner.RunWith; +import org.junit.runners.JUnit4; + +/** Tests for {@link GrowableOffsetRangeTracker}. */ +@RunWith(JUnit4.class) +public class GrowableOffsetRangeTrackerTest { + private static class SimplePoller implements GrowableOffsetRangeTracker.RangeEndEstimator { + private long estimateRangeEnd = 0; + + @Override + public long estimate() { + return estimateRangeEnd; + } + + public void setEstimateRangeEnd(long offset) { + estimateRangeEnd = offset; + } + } + + @Rule public final ExpectedException expected = ExpectedException.none(); + + @Test + public void testIllegalInitialization() throws Exception { + expected.expect(NullPointerException.class); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, null); + } + + @Test + public void testTryClaim() throws Exception { + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, new SimplePoller()); + assertTrue(tracker.tryClaim(10L)); + assertTrue(tracker.tryClaim(100L)); + assertFalse(tracker.tryClaim(Long.MAX_VALUE)); + tracker.checkDone(); + } + + @Test + public void testCheckpointBeforeStart() throws Exception { + SimplePoller poller = new SimplePoller(); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, poller); + poller.setEstimateRangeEnd(10); + SplitResult res = tracker.trySplit(0); + tracker.checkDone(); + assertEquals(new OffsetRange(0, 0), res.getPrimary()); + assertEquals(new OffsetRange(0, 0), tracker.currentRestriction()); + assertEquals(new OffsetRange(0, Long.MAX_VALUE), res.getResidual()); + } + + @Test + public void testCheckpointJustStarted() throws Exception { + SimplePoller poller = new SimplePoller(); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, poller); + assertTrue(tracker.tryClaim(5L)); + poller.setEstimateRangeEnd(0L); + SplitResult res = tracker.trySplit(0); + tracker.checkDone(); + assertEquals(new OffsetRange(0, 6), res.getPrimary()); + assertEquals(new OffsetRange(0, 6), tracker.currentRestriction()); + assertEquals(new OffsetRange(6, Long.MAX_VALUE), res.getResidual()); + + tracker = new GrowableOffsetRangeTracker(0L, poller); + assertTrue(tracker.tryClaim(5L)); + poller.setEstimateRangeEnd(20L); + res = tracker.trySplit(0); + tracker.checkDone(); + assertEquals(new OffsetRange(0, 6), res.getPrimary()); + assertEquals(new OffsetRange(6, Long.MAX_VALUE), res.getResidual()); + } + + @Test + public void testCheckpointAfterAllProcessed() throws Exception { + SimplePoller poller = new SimplePoller(); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, poller); + assertFalse(tracker.tryClaim(Long.MAX_VALUE)); + tracker.checkDone(); + assertNull(tracker.trySplit(0)); + } + + @Test + public void testCheckpointAtEmptyRange() throws Exception { + GrowableOffsetRangeTracker tracker = + new GrowableOffsetRangeTracker(Long.MAX_VALUE, new SimplePoller()); + tracker.checkDone(); + assertNull(tracker.trySplit(0)); + } + + @Test + public void testSplit() throws Exception { + SimplePoller poller = new SimplePoller(); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, poller); + assertTrue(tracker.tryClaim(0L)); + + poller.setEstimateRangeEnd(16L); + // The split of infinite range results in one finite range and on infinite range. Review comment: ```suggestion // The split of infinite range results in one finite range and one infinite range. ``` ########## File path: sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTrackerTest.java ########## @@ -0,0 +1,231 @@ +/* + * 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.transforms.splittabledofn; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertNull; +import static org.junit.Assert.assertTrue; + +import org.apache.beam.sdk.io.range.OffsetRange; +import org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker.Progress; +import org.junit.Rule; +import org.junit.Test; +import org.junit.rules.ExpectedException; +import org.junit.runner.RunWith; +import org.junit.runners.JUnit4; + +/** Tests for {@link GrowableOffsetRangeTracker}. */ +@RunWith(JUnit4.class) +public class GrowableOffsetRangeTrackerTest { + private static class SimplePoller implements GrowableOffsetRangeTracker.RangeEndEstimator { Review comment: nit: SimplePoller -> SimpleEstimator ########## File path: sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTrackerTest.java ########## @@ -0,0 +1,231 @@ +/* + * 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.transforms.splittabledofn; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertNull; +import static org.junit.Assert.assertTrue; + +import org.apache.beam.sdk.io.range.OffsetRange; +import org.apache.beam.sdk.transforms.splittabledofn.RestrictionTracker.Progress; +import org.junit.Rule; +import org.junit.Test; +import org.junit.rules.ExpectedException; +import org.junit.runner.RunWith; +import org.junit.runners.JUnit4; + +/** Tests for {@link GrowableOffsetRangeTracker}. */ +@RunWith(JUnit4.class) +public class GrowableOffsetRangeTrackerTest { + private static class SimplePoller implements GrowableOffsetRangeTracker.RangeEndEstimator { + private long estimateRangeEnd = 0; + + @Override + public long estimate() { + return estimateRangeEnd; + } + + public void setEstimateRangeEnd(long offset) { + estimateRangeEnd = offset; + } + } + + @Rule public final ExpectedException expected = ExpectedException.none(); + + @Test + public void testIllegalInitialization() throws Exception { + expected.expect(NullPointerException.class); + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, null); + } + + @Test + public void testTryClaim() throws Exception { + GrowableOffsetRangeTracker tracker = new GrowableOffsetRangeTracker(0L, new SimplePoller()); + assertTrue(tracker.tryClaim(10L)); + assertTrue(tracker.tryClaim(100L)); + assertFalse(tracker.tryClaim(Long.MAX_VALUE)); + tracker.checkDone(); + } + + @Test + public void testCheckpointBeforeStart() throws Exception { + SimplePoller poller = new SimplePoller(); Review comment: nit: poller -> estimator here and elsewhere in this test ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,115 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code Long.MAX_VALUE} is + * used as end range to indicate the possibility of infinity. + * + * <p>An offset range is considered growable when the end offset could grow (or change) during + * execution time (e.g., Kafka topic partition offset, appended file, ...). + * + * <p>The growable range is marked as done by claiming {@code Long.MAX_VALUE}. + */ +@Experimental(Kind.SPLITTABLE_DO_FN) +public class GrowableOffsetRangeTracker extends OffsetRangeTracker { + /** + * An interface that should be implemented to fetch estimated end offset of the range. + * + * <p>{@code estimateRangeEnd} is called to give the end offset when {@code trySplit} or {@code + * getProgress} is invoked. The end offset is exclusive for the range. The estimated end is not + * necessary to increase monotonically as it will only be taken into computation when the estimate + * end is larger than the current position. When returning {@code Long.MAX_VALUE} as estimate, it + * means the largest possible position for the range is {@code Long.MAX_VALUE - 1}. If there is + * not an estimate yet, {@code Long.MIN_VALUE} should be returned, where estimated end will not + * effect progress and split. + * + * <p>Having a good estimate is important for providing a good signal of progress and splitting at + * a proper position. + * + * <p>If {@code estimate()} is expensive to call, please consider wrapping the implementation with + * {@code Suppliers.memoizeWithExpiration} as an optimization. Review comment: ```suggestion * Provides the estimated end offset of the range. * * <p>{@link #estimate} is called to give the end offset when {@link #trySplit} or {@link * #getProgress} is invoked. The end offset is exclusive for the range. The estimated end is not * required to monotonically increase as it will only be taken into consideration when the estimated * end offset is larger than the current position. Returning {@code Long.MAX_VALUE} as the estimate * implies the largest possible position for the range is {@code Long.MAX_VALUE - 1}. Return {@code Long.MIN_VALUE} if an estimate can not be provided. * * <p>Providing a good estimate is important for an accurate progress signal and will impact splitting decisions by * the runner. * * <p>If {@link #estimate} is expensive to compute, consider wrapping the implementation with * {@link Suppliers.memoizeWithExpiration} or equivalent as an optimization. ``` ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,115 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code Long.MAX_VALUE} is + * used as end range to indicate the possibility of infinity. + * + * <p>An offset range is considered growable when the end offset could grow (or change) during + * execution time (e.g., Kafka topic partition offset, appended file, ...). + * + * <p>The growable range is marked as done by claiming {@code Long.MAX_VALUE}. + */ +@Experimental(Kind.SPLITTABLE_DO_FN) +public class GrowableOffsetRangeTracker extends OffsetRangeTracker { + /** + * An interface that should be implemented to fetch estimated end offset of the range. + * + * <p>{@code estimateRangeEnd} is called to give the end offset when {@code trySplit} or {@code + * getProgress} is invoked. The end offset is exclusive for the range. The estimated end is not + * necessary to increase monotonically as it will only be taken into computation when the estimate + * end is larger than the current position. When returning {@code Long.MAX_VALUE} as estimate, it + * means the largest possible position for the range is {@code Long.MAX_VALUE - 1}. If there is + * not an estimate yet, {@code Long.MIN_VALUE} should be returned, where estimated end will not + * effect progress and split. + * + * <p>Having a good estimate is important for providing a good signal of progress and splitting at + * a proper position. + * + * <p>If {@code estimate()} is expensive to call, please consider wrapping the implementation with + * {@code Suppliers.memoizeWithExpiration} as an optimization. + */ + @FunctionalInterface + public interface RangeEndEstimator { + long estimate(); + } + + private final RangeEndEstimator rangeEndEstimator; + + public GrowableOffsetRangeTracker(long start, RangeEndEstimator rangeEndEstimator) { + super(new OffsetRange(start, Long.MAX_VALUE)); + this.rangeEndEstimator = checkNotNull(rangeEndEstimator); + } + + @Override + public SplitResult<OffsetRange> trySplit(double fractionOfRemainder) { + // If current tracking range is no longer growable, split it as a normal range. + if (range.getTo() != Long.MAX_VALUE || range.getTo() == range.getFrom()) { + return super.trySplit(fractionOfRemainder); + } + // If current range has been done, there is no more space to split. + if (lastAttemptedOffset != null && lastAttemptedOffset == Long.MAX_VALUE) { + return null; + } + double cur = + (lastAttemptedOffset == null) ? (double) range.getFrom() - 1 : (double) lastAttemptedOffset; + + // Fetch the estimated end offset. If the estimated end is smaller than the next offset, use + // the next offset as end. + double estimateRangeEnd = Math.max(rangeEndEstimator.estimate(), cur + 1); + + // Convert to double in computation to prevent overflow, which may result in lost of some + // accuracy. + double splitPos = cur + Math.max(1L, (estimateRangeEnd - cur) * fractionOfRemainder); + long split = Double.valueOf(splitPos).longValue(); + if (split > Double.valueOf(estimateRangeEnd).longValue()) { + return null; + } + OffsetRange res = new OffsetRange(split, range.getTo()); + this.range = new OffsetRange(range.getFrom(), split); + return SplitResult.of(range, res); + } + + @Override + public Progress getProgress() { + // If current tracking range is no longer growable, get progress as a normal range. + if (range.getTo() != Long.MAX_VALUE || range.getTo() == range.getFrom()) { + return super.getProgress(); + } + + // Convert to double in computation to prevent overflow, which may result in lost of some + // accuracy. Review comment: ```suggestion // Convert to double in computation to prevent overflow, which may result in lost of // precision. ``` ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,115 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code Long.MAX_VALUE} is + * used as end range to indicate the possibility of infinity. Review comment: ```suggestion * used as the end of the range to indicate infinity. ``` ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,103 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * A special {@link OffsetRangeTracker} for tracking a growable offset range. The Long.MAX_VALUE is + * used as end range to indicate the possibility of infinity. + * + * <p>A offset range is considered as growable when the end offset could grow(or change) during + * execution time(e.g., Kafka backlog, appended file). + */ +@Experimental(Kind.SPLITTABLE_DO_FN) +public class GrowableOffsetRangeTracker extends OffsetRangeTracker { + /** + * An interface that should be implemented to fetch estimated end offset of range. + * + * <p>{@code estimateRangeEnd} is called to give te end offset when {@code trySplit} or {@code + * getProgress} is invoked. The end offset is exclusive for the range. It's not necessary to + * increase monotonically but it's only taken into computation when it's larger than the current + * position. When returning Long.MAX_VALUE as estimate, it means the largest possible position for + * the range is Long.MAX_VALUE - 1. Having a good estimate is important for providing a good + * signal of progress and splitting at a proper position. + */ + public interface OffsetPoller { + long estimateRangeEnd(); + } + + private final OffsetPoller poller; + + public GrowableOffsetRangeTracker(long start, OffsetPoller offsetPoller) { + super(new OffsetRange(start, Long.MAX_VALUE)); + this.poller = checkNotNull(offsetPoller); + } + + @Override + public SplitResult<OffsetRange> trySplit(double fractionOfRemainder) { + // If current tracking range is no longer growable, split it as a normal range. + if (range.getTo() != Long.MAX_VALUE || range.getTo() == range.getFrom()) { Review comment: Sorry for the confusion, I misread the if statement earlier. ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/OffsetRangeTracker.java ########## @@ -50,16 +53,17 @@ public OffsetRange currentRestriction() { @Override public SplitResult<OffsetRange> trySplit(double fractionOfRemainder) { - long cur = (lastAttemptedOffset == null) ? range.getFrom() - 1 : lastAttemptedOffset; - long splitPos = - cur - + Math.max( - 1L, (Double.valueOf((range.getTo() - cur) * fractionOfRemainder)).longValue()); - if (splitPos >= range.getTo()) { + // Convert to double in computation to prevent overflow, which may result in lost of some + // accuracy. Review comment: ```suggestion // Convert to double in computation to prevent overflow, which may result in loss of // precision. ``` ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,115 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code Long.MAX_VALUE} is + * used as end range to indicate the possibility of infinity. + * + * <p>An offset range is considered growable when the end offset could grow (or change) during + * execution time (e.g., Kafka topic partition offset, appended file, ...). + * + * <p>The growable range is marked as done by claiming {@code Long.MAX_VALUE}. + */ +@Experimental(Kind.SPLITTABLE_DO_FN) +public class GrowableOffsetRangeTracker extends OffsetRangeTracker { + /** + * An interface that should be implemented to fetch estimated end offset of the range. + * + * <p>{@code estimateRangeEnd} is called to give the end offset when {@code trySplit} or {@code + * getProgress} is invoked. The end offset is exclusive for the range. The estimated end is not + * necessary to increase monotonically as it will only be taken into computation when the estimate + * end is larger than the current position. When returning {@code Long.MAX_VALUE} as estimate, it + * means the largest possible position for the range is {@code Long.MAX_VALUE - 1}. If there is + * not an estimate yet, {@code Long.MIN_VALUE} should be returned, where estimated end will not + * effect progress and split. + * + * <p>Having a good estimate is important for providing a good signal of progress and splitting at + * a proper position. + * + * <p>If {@code estimate()} is expensive to call, please consider wrapping the implementation with + * {@code Suppliers.memoizeWithExpiration} as an optimization. + */ + @FunctionalInterface + public interface RangeEndEstimator { + long estimate(); + } + + private final RangeEndEstimator rangeEndEstimator; + + public GrowableOffsetRangeTracker(long start, RangeEndEstimator rangeEndEstimator) { + super(new OffsetRange(start, Long.MAX_VALUE)); + this.rangeEndEstimator = checkNotNull(rangeEndEstimator); + } + + @Override + public SplitResult<OffsetRange> trySplit(double fractionOfRemainder) { + // If current tracking range is no longer growable, split it as a normal range. + if (range.getTo() != Long.MAX_VALUE || range.getTo() == range.getFrom()) { + return super.trySplit(fractionOfRemainder); + } + // If current range has been done, there is no more space to split. + if (lastAttemptedOffset != null && lastAttemptedOffset == Long.MAX_VALUE) { + return null; + } + double cur = + (lastAttemptedOffset == null) ? (double) range.getFrom() - 1 : (double) lastAttemptedOffset; + + // Fetch the estimated end offset. If the estimated end is smaller than the next offset, use + // the next offset as end. + double estimateRangeEnd = Math.max(rangeEndEstimator.estimate(), cur + 1); + + // Convert to double in computation to prevent overflow, which may result in lost of some + // accuracy. Review comment: ```suggestion // Convert to double in computation to prevent overflow, which may result in loss of // precision. ``` ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java ########## @@ -0,0 +1,115 @@ +/* + * 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.transforms.splittabledofn; + +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkNotNull; + +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; +import org.apache.beam.sdk.io.range.OffsetRange; + +/** + * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code Long.MAX_VALUE} is + * used as end range to indicate the possibility of infinity. + * + * <p>An offset range is considered growable when the end offset could grow (or change) during + * execution time (e.g., Kafka topic partition offset, appended file, ...). + * + * <p>The growable range is marked as done by claiming {@code Long.MAX_VALUE}. + */ +@Experimental(Kind.SPLITTABLE_DO_FN) +public class GrowableOffsetRangeTracker extends OffsetRangeTracker { + /** + * An interface that should be implemented to fetch estimated end offset of the range. + * + * <p>{@code estimateRangeEnd} is called to give the end offset when {@code trySplit} or {@code + * getProgress} is invoked. The end offset is exclusive for the range. The estimated end is not + * necessary to increase monotonically as it will only be taken into computation when the estimate + * end is larger than the current position. When returning {@code Long.MAX_VALUE} as estimate, it + * means the largest possible position for the range is {@code Long.MAX_VALUE - 1}. If there is + * not an estimate yet, {@code Long.MIN_VALUE} should be returned, where estimated end will not + * effect progress and split. + * + * <p>Having a good estimate is important for providing a good signal of progress and splitting at + * a proper position. + * + * <p>If {@code estimate()} is expensive to call, please consider wrapping the implementation with + * {@code Suppliers.memoizeWithExpiration} as an optimization. + */ + @FunctionalInterface + public interface RangeEndEstimator { + long estimate(); + } + + private final RangeEndEstimator rangeEndEstimator; + + public GrowableOffsetRangeTracker(long start, RangeEndEstimator rangeEndEstimator) { + super(new OffsetRange(start, Long.MAX_VALUE)); + this.rangeEndEstimator = checkNotNull(rangeEndEstimator); + } + + @Override + public SplitResult<OffsetRange> trySplit(double fractionOfRemainder) { + // If current tracking range is no longer growable, split it as a normal range. + if (range.getTo() != Long.MAX_VALUE || range.getTo() == range.getFrom()) { + return super.trySplit(fractionOfRemainder); + } + // If current range has been done, there is no more space to split. + if (lastAttemptedOffset != null && lastAttemptedOffset == Long.MAX_VALUE) { + return null; + } + double cur = Review comment: We should only use doubles if there would be an issue with overflow. For really large long values we can have the math be incorrect which can lead to the splitPos being before from or after to even though with higher precision we would get something that works. For example: ``` long a = 123456789012345677L; long b = 123456789012345679L; long c = 123456789012345680L; double ad = a; double bd = b; double cd = c; System.out.println((long)ad + " " + (long)bd + " " + (long)cd); ``` prints ``` 123456789012345680 123456789012345680 123456789012345680 ``` Worthwhile to have a test which exercises a case where `from = 123456789012345677L` and `to = 123456789012345679L` and we can have a split in between. Also worthwhile to test `from = 123456789012345681L` and `to = 123456789012345683L`. All these values (and the values in between) when converted to double and back to long round to `123456789012345680L`. We can solve this by having two ways to calculate this or using BigDecimal. The two ways to calculate method would use longs when (estimateRangeEnd - cur) won't overflow and doubles otherwise. Using BigDecimal with a MathContext with enough precision wouldn't run into this either and would only require one implemention (I believe DECIMAL128 should have enough precision to not run into this issue). ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/OffsetRangeTracker.java ########## @@ -120,13 +124,16 @@ public String toString() { public Progress getProgress() { // If we have never attempted an offset, we return the length of the entire range as work // remaining. + // Convert to double in computation to prevent overflow, which may result in lost of some + // accuracy. Review comment: ```suggestion // Convert to double in computation to prevent overflow, which may result in loss of // precision. ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
