cmccabe commented on a change in pull request #9901: URL: https://github.com/apache/kafka/pull/9901#discussion_r567014310
########## File path: metadata/src/main/java/org/apache/kafka/timeline/SnapshotRegistry.java ########## @@ -0,0 +1,251 @@ +/* + * 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.kafka.timeline; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.Iterator; +import java.util.List; +import java.util.ListIterator; +import java.util.NoSuchElementException; +import java.util.stream.Collectors; + +import org.apache.kafka.common.utils.LogContext; +import org.slf4j.Logger; + + +/** + * A registry containing snapshots of timeline data structures. + * We generally expect a small number of snapshots-- perhaps 1 or 2 at a time. + * Therefore, we use ArrayLists here rather than a data structure with higher overhead. + */ +public class SnapshotRegistry { + class SnapshotIterator implements ListIterator<Snapshot> { + private Snapshot cur; + private Snapshot lastResult = null; + + SnapshotIterator(Snapshot startAfter) { + this.cur = startAfter; + } + + @Override + public boolean hasNext() { + return cur.next() != head; + } + + @Override + public Snapshot next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + cur = cur.next(); + lastResult = cur; + return cur; + } + + @Override + public boolean hasPrevious() { + return cur != head; + } + + @Override + public Snapshot previous() { + if (!hasPrevious()) { + throw new NoSuchElementException(); + } + Snapshot result = cur; + cur = cur.prev(); + lastResult = result; + return result; + } + + @Override + public int nextIndex() { + throw new UnsupportedOperationException(); + } + + @Override + public int previousIndex() { + throw new UnsupportedOperationException(); + } + + @Override + public void remove() { + if (lastResult == null) { + throw new IllegalStateException(); + } + if (cur == lastResult) { + cur = cur.prev(); + } + snapshots.remove(lastResult.epoch()); + lastResult.removeSelfFromList(); + lastResult = null; + } + + @Override + public void set(Snapshot snapshot) { + throw new UnsupportedOperationException(); + } + + @Override + public void add(Snapshot snapshot) { + if (cur.epoch() >= snapshot.epoch()) { + throw new IllegalArgumentException("Can't add snapshot " + + snapshot.epoch() + " after snapshot " + cur.epoch()); + } + cur.add(snapshot); + cur = snapshot; + } + } + + private final Logger log; + + /** + * A map from snapshot epochs to snapshot data structures. + */ + private final HashMap<Long, Snapshot> snapshots = new HashMap<>(); + + /** + * The head of a list of snapshots, sorted by epoch. + */ + private final Snapshot head = new Snapshot(-1); + + public SnapshotRegistry(LogContext logContext) { + this.log = logContext.logger(SnapshotRegistry.class); + } + + /** + * Returns an iterator that moves through snapshots from the lowest to the highest epoch. + */ + public ListIterator<Snapshot> iterator() { + return new SnapshotIterator(head); + } + + /** + * Returns an iterator that moves through snapshots from the lowest to the highest epoch. + * + * @param startAfter A snapshot that we should start after. + */ + ListIterator<Snapshot> iterator(Snapshot startAfter) { + return new SnapshotIterator(startAfter); + } + + /** + * Returns a sorted list of snapshot epochs. + */ + List<Long> epochsList() { + List<Long> result = new ArrayList<>(); + for (ListIterator<Snapshot> iterator = iterator(); iterator.hasNext(); ) { + result.add(iterator.next().epoch()); + } + return result; + } + + /** + * Gets the snapshot for a specific epoch. + */ + public Snapshot get(long epoch) { + Snapshot snapshot = snapshots.get(epoch); + if (snapshot == null) { + throw new RuntimeException("No snapshot for epoch " + epoch + ". Snapshot " + + "epochs are: " + epochsList().stream().map(e -> e.toString()). + collect(Collectors.joining(", "))); + } + return snapshot; + } + + /** + * Creates a new snapshot at the given epoch. + * + * @param epoch The epoch to create the snapshot at. The current epoch + * will be advanced to one past this epoch. + */ + public Snapshot createSnapshot(long epoch) { + Snapshot last = head.prev(); + if (last.epoch() >= epoch) { + throw new RuntimeException("Can't create a new snapshot at epoch " + epoch + + " because there is already a snapshot with epoch " + last.epoch()); + } + Snapshot snapshot = new Snapshot(epoch); + last.add(snapshot); + snapshots.put(epoch, snapshot); + log.debug("Creating snapshot {}", epoch); + System.out.println("WATERMELON: snapshots = " + snapshots); Review comment: fixed ########## File path: metadata/src/main/java/org/apache/kafka/timeline/SnapshotRegistry.java ########## @@ -0,0 +1,251 @@ +/* + * 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.kafka.timeline; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.Iterator; +import java.util.List; +import java.util.ListIterator; +import java.util.NoSuchElementException; +import java.util.stream.Collectors; + +import org.apache.kafka.common.utils.LogContext; +import org.slf4j.Logger; + + +/** + * A registry containing snapshots of timeline data structures. + * We generally expect a small number of snapshots-- perhaps 1 or 2 at a time. + * Therefore, we use ArrayLists here rather than a data structure with higher overhead. + */ +public class SnapshotRegistry { + class SnapshotIterator implements ListIterator<Snapshot> { + private Snapshot cur; + private Snapshot lastResult = null; + + SnapshotIterator(Snapshot startAfter) { + this.cur = startAfter; + } + + @Override + public boolean hasNext() { + return cur.next() != head; + } + + @Override + public Snapshot next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + cur = cur.next(); + lastResult = cur; + return cur; + } + + @Override + public boolean hasPrevious() { + return cur != head; + } + + @Override + public Snapshot previous() { + if (!hasPrevious()) { + throw new NoSuchElementException(); + } + Snapshot result = cur; + cur = cur.prev(); + lastResult = result; + return result; + } + + @Override + public int nextIndex() { + throw new UnsupportedOperationException(); + } + + @Override + public int previousIndex() { + throw new UnsupportedOperationException(); + } + + @Override + public void remove() { + if (lastResult == null) { + throw new IllegalStateException(); + } + if (cur == lastResult) { + cur = cur.prev(); + } + snapshots.remove(lastResult.epoch()); + lastResult.removeSelfFromList(); + lastResult = null; + } + + @Override + public void set(Snapshot snapshot) { + throw new UnsupportedOperationException(); + } + + @Override + public void add(Snapshot snapshot) { + if (cur.epoch() >= snapshot.epoch()) { + throw new IllegalArgumentException("Can't add snapshot " + + snapshot.epoch() + " after snapshot " + cur.epoch()); + } + cur.add(snapshot); + cur = snapshot; + } + } + + private final Logger log; + + /** + * A map from snapshot epochs to snapshot data structures. + */ + private final HashMap<Long, Snapshot> snapshots = new HashMap<>(); + + /** + * The head of a list of snapshots, sorted by epoch. + */ + private final Snapshot head = new Snapshot(-1); + + public SnapshotRegistry(LogContext logContext) { + this.log = logContext.logger(SnapshotRegistry.class); + } + + /** + * Returns an iterator that moves through snapshots from the lowest to the highest epoch. + */ + public ListIterator<Snapshot> iterator() { + return new SnapshotIterator(head); + } + + /** + * Returns an iterator that moves through snapshots from the lowest to the highest epoch. + * + * @param startAfter A snapshot that we should start after. + */ + ListIterator<Snapshot> iterator(Snapshot startAfter) { + return new SnapshotIterator(startAfter); + } + + /** + * Returns a sorted list of snapshot epochs. + */ + List<Long> epochsList() { + List<Long> result = new ArrayList<>(); + for (ListIterator<Snapshot> iterator = iterator(); iterator.hasNext(); ) { + result.add(iterator.next().epoch()); + } + return result; + } + + /** + * Gets the snapshot for a specific epoch. + */ + public Snapshot get(long epoch) { + Snapshot snapshot = snapshots.get(epoch); + if (snapshot == null) { + throw new RuntimeException("No snapshot for epoch " + epoch + ". Snapshot " + + "epochs are: " + epochsList().stream().map(e -> e.toString()). + collect(Collectors.joining(", "))); + } + return snapshot; + } + + /** + * Creates a new snapshot at the given epoch. + * + * @param epoch The epoch to create the snapshot at. The current epoch + * will be advanced to one past this epoch. + */ + public Snapshot createSnapshot(long epoch) { + Snapshot last = head.prev(); + if (last.epoch() >= epoch) { + throw new RuntimeException("Can't create a new snapshot at epoch " + epoch + + " because there is already a snapshot with epoch " + last.epoch()); + } + Snapshot snapshot = new Snapshot(epoch); + last.add(snapshot); + snapshots.put(epoch, snapshot); + log.debug("Creating snapshot {}", epoch); + System.out.println("WATERMELON: snapshots = " + snapshots); + Snapshot n = head.next(); + while (n != head) { + System.out.println("WATERMELON: n = " + n.epoch() + " n.prev = " + n.prev() + " n.next = " + n.next()); Review comment: fixed ---------------------------------------------------------------- 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. 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