jordanly commented on a change in pull request #37: Staggered (Variable batch) Updates URL: https://github.com/apache/aurora/pull/37#discussion_r221015716
########## File path: src/main/java/org/apache/aurora/scheduler/updater/strategy/VariableBatchStrategy.java ########## @@ -0,0 +1,152 @@ +/** + * Licensed 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.aurora.scheduler.updater.strategy; + +import java.util.List; +import java.util.Objects; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +import com.google.common.base.Preconditions; +import com.google.common.collect.ImmutableList; +import com.google.common.collect.ImmutableSet; +import com.google.common.collect.Ordering; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A strategy that limits the number of instances selected by the subclass using variable steps. + * + * @param <T> Instance type. + */ +public class VariableBatchStrategy<T extends Comparable<T>> implements UpdateStrategy<T> { + private final Ordering<T> ordering; + protected final ImmutableList<Integer> maxActiveGroups; + private final boolean rollingForward; + private Optional<Integer> totalModInstanceCount; + + private static final Logger LOG = LoggerFactory.getLogger(VariableBatchStrategy.class); + + /** + * Creates a variable active-limited strategy that applies an upper bound to all results. + * + * @param maxActiveGroups List of Maximum group sizes. Each group size represents a step. + * {@link #getNextGroup(Set, Set)}. + */ + public VariableBatchStrategy(Ordering<T> ordering, + List<Integer> maxActiveGroups, + boolean rollingForward) { + + this.ordering = Objects.requireNonNull(ordering); + this.rollingForward = rollingForward; + + maxActiveGroups.forEach(x -> Preconditions.checkArgument(x > 0)); + + this.maxActiveGroups = ImmutableList.copyOf(maxActiveGroups); + this.totalModInstanceCount = Optional.empty(); + } + + // Determine how far we're into the update based upon how many instances are waiting + // to be modified. + private int determineCurGroupSize(int remaining) { + + // Calculate which groupIndex we are in by finding out how many instances we have left to update + int modified = totalModInstanceCount.get() - remaining; + + int lastGroupSize = maxActiveGroups.get(maxActiveGroups.size() - 1); + + LOG.debug("Variable Batch Update progress: {} instances have been modified, " + + "{} instances remain unmodified, and {} overall instances to be modified.", + modified, + remaining, + totalModInstanceCount.get()); + + if (rollingForward) { + + int sum = 0; + for (Integer groupSize : maxActiveGroups) { + sum += groupSize; + + if (sum > modified) { + return groupSize; + } + } + // Return last step when number of instances > sum of all groups + return lastGroupSize; + } else { + + // To perform the update in reverse, we use the number of remaining tasks left to update + // instead of using the number of already modified instances. In a rollback, the remaining + // count represents the number of instances that were already modified while rolling forward + // and need to be reverted. + int curGroupSize = remaining; + + for (Integer groupSize : maxActiveGroups) { + // This handles an in between step. i.e.: updated instances = 4, update groups = [2,3] + // which results in update groups 2 and 2 rolling forward at the time of failure. + if (curGroupSize <= groupSize) { + return curGroupSize; + } + + curGroupSize -= groupSize; + } + + // Handle the case where number of instances update were + // greater than the sum of all update groups + // Calculate the size of the last update group size performed while rolling forward. + curGroupSize = curGroupSize % lastGroupSize; + if (curGroupSize == 0) { + return lastGroupSize; + } else { + return curGroupSize; + } + } + } + + @Override + public final Set<T> getNextGroup(Set<T> idle, Set<T> active) { + + // Get the size for the idle set on the first run only. This is representative of the number + // of overall instance modifications this update will trigger. + if (!totalModInstanceCount.isPresent()) { + totalModInstanceCount = Optional.of(idle.size()); + } + + // Limit group size to the current size of the group minus the number of instances currently + // being modified. + return ordering.sortedCopy(doGetNextGroup(idle, active)).stream() + .limit(Math.max(0, determineCurGroupSize(idle.size()) - active.size())) + .collect(Collectors.toSet()); + } + + /** + * Return a list of instances to be updated. + * Returns an empty list if the current active group has not completed. + * If the result is larger than the current group size in {@link #maxActiveGroups}, + * it will be truncated. + * + * @param idle Idle instances, candidate for being updated. + * @param active Instances currently being updated. + * @return A subset of {@code idle}, instances to start updating. + */ + Set<T> doGetNextGroup(Set<T> idle, Set<T> active) { + if (active.isEmpty()) { Review comment: I would copy the current `BatchStrategy` impl of this since it is the same: `return active.isEmpty() ? idle : ImmutableSet.of();` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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