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https://issues.apache.org/jira/browse/BEAM-9977?focusedWorklogId=435694&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-435694
]
ASF GitHub Bot logged work on BEAM-9977:
----------------------------------------
Author: ASF GitHub Bot
Created on: 20/May/20 21:05
Start Date: 20/May/20 21:05
Worklog Time Spent: 10m
Work Description: lukecwik commented on a change in pull request #11715:
URL: https://github.com/apache/beam/pull/11715#discussion_r428304723
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/GrowableOffsetRangeTracker.java
##########
@@ -0,0 +1,143 @@
+/*
+ * 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 java.math.BigDecimal;
+import java.math.MathContext;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.annotations.Experimental.Kind;
+import org.apache.beam.sdk.io.range.OffsetRange;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Suppliers;
+
+/**
+ * An {@link OffsetRangeTracker} for tracking a growable offset range. {@code
Long.MAX_VALUE} is
+ * used as the end of the range to indicate 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 {
+ /**
+ * 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.
+ *
+ * <p>TODO(BEAM-10032): Also consider using {@link RangeEndEstimator} when
the range is not ended
+ * with {@code Long.MAX_VALUE}.
+ */
+ @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;
+ }
+ BigDecimal cur =
+ (lastAttemptedOffset == null)
+ ? BigDecimal.valueOf(range.getFrom()).subtract(BigDecimal.ONE,
MathContext.DECIMAL128)
+ : BigDecimal.valueOf(lastAttemptedOffset);
+
+ // Fetch the estimated end offset. If the estimated end is smaller than
the next offset, use
+ // the next offset as end.
+ BigDecimal estimateRangeEnd =
+ BigDecimal.valueOf(rangeEndEstimator.estimate())
+ .max(cur.add(BigDecimal.ONE, MathContext.DECIMAL128));
+
+ // Convert to BigDecimal in computation to prevent overflow, which may
result in loss of
+ // precision.
+ // split = cur + max(1, (estimateRangeEnd - cur) * fractionOfRemainder)
+ BigDecimal splitPos =
+ cur.add(
+ estimateRangeEnd
+ .subtract(cur, MathContext.DECIMAL128)
+ .multiply(BigDecimal.valueOf(fractionOfRemainder),
MathContext.DECIMAL128)
+ .max(BigDecimal.ONE),
+ MathContext.DECIMAL128);
+ long split = splitPos.longValue();
+ if (split > 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 BigDecimal in computation to prevent overflow, which may
result in lost of
+ // precision.
+ BigDecimal estimateRangeEnd =
BigDecimal.valueOf(rangeEndEstimator.estimate());
+
+ if (lastAttemptedOffset == null) {
+ return Progress.from(
+ 0,
+ estimateRangeEnd
+ .subtract(BigDecimal.valueOf(range.getFrom()),
MathContext.DECIMAL128)
+ .max(BigDecimal.ZERO)
+ .doubleValue());
+ }
+
+ BigDecimal workRemaining =
+ estimateRangeEnd
+ .subtract(BigDecimal.valueOf(lastAttemptedOffset),
MathContext.DECIMAL128)
+ .max(BigDecimal.ZERO);
+ BigDecimal totalWork =
+ estimateRangeEnd
+ .max(BigDecimal.valueOf(lastAttemptedOffset))
+ .subtract(BigDecimal.valueOf(range.getFrom()));
Review comment:
Doesn't this subtract need the DECIMAL128 math context?
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/OffsetRangeTracker.java
##########
@@ -120,13 +136,27 @@ 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 BigDecimal in computation to prevent overflow, which may
result in loss of
+ // precision.
if (lastAttemptedOffset == null) {
- return Progress.from(0, range.getTo() - range.getFrom());
+ return Progress.from(
+ 0,
+ BigDecimal.valueOf(range.getTo())
+ .subtract(BigDecimal.valueOf(range.getFrom()),
MathContext.DECIMAL128)
+ .doubleValue());
}
// Compute the amount of work remaining from where we are to where we are
attempting to get to
// with a minimum of zero in case we have claimed beyond the end of the
range.
- long workRemaining = Math.max(range.getTo() - lastAttemptedOffset, 0);
- return Progress.from(range.getTo() - range.getFrom() - workRemaining,
workRemaining);
+ BigDecimal workRemaining =
+ BigDecimal.valueOf(range.getTo())
+ .subtract(BigDecimal.valueOf(lastAttemptedOffset),
MathContext.DECIMAL128)
+ .max(BigDecimal.ZERO);
+ BigDecimal wholeWork =
Review comment:
nit: `wholeWork` -> `totalWork`
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Issue Time Tracking
-------------------
Worklog Id: (was: 435694)
Time Spent: 3h 20m (was: 3h 10m)
> Build Kafka Read on top of Java SplittableDoFn
> ----------------------------------------------
>
> Key: BEAM-9977
> URL: https://issues.apache.org/jira/browse/BEAM-9977
> Project: Beam
> Issue Type: New Feature
> Components: io-java-kafka
> Reporter: Boyuan Zhang
> Assignee: Boyuan Zhang
> Priority: P2
> Time Spent: 3h 20m
> Remaining Estimate: 0h
>
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