stevenzwu commented on code in PR #17322: URL: https://github.com/apache/iceberg/pull/17322#discussion_r3646737028
########## core/src/main/java/org/apache/iceberg/ContentStatsBackedMap.java: ########## @@ -0,0 +1,181 @@ +/* + * 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.iceberg; + +import java.nio.ByteBuffer; +import java.util.AbstractMap; +import java.util.Map; +import java.util.Set; +import org.apache.iceberg.relocated.com.google.common.collect.Sets; +import org.apache.iceberg.types.Conversions; +import org.apache.iceberg.types.Type; + +/** + * A lazy, read-only {@link Map} view of one stat across the columns of a {@link ContentStats}, + * keyed by field ID, mirroring the per-column stat maps on {@link ContentFile}. + */ +class ContentStatsBackedMap<V> extends AbstractMap<Integer, V> { + private enum Kind { + VALUE_COUNT, + NULL_VALUE_COUNT, + NAN_VALUE_COUNT, + LOWER_BOUND, + UPPER_BOUND + } + + /** Per-column value counts, or {@code null} if no column tracks the value count. */ + static <V> Map<Integer, V> valueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.VALUE_COUNT); + } + + /** Per-column null value counts, or {@code null} if no column tracks the null value count. */ + static <V> Map<Integer, V> nullValueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.NULL_VALUE_COUNT); + } + + /** Per-column NaN value counts, or {@code null} if no column tracks the NaN value count. */ + static <V> Map<Integer, V> nanValueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.NAN_VALUE_COUNT); + } + + /** Per-column lower bounds, or {@code null} if no column tracks a lower bound. */ + static <V> Map<Integer, V> lowerBounds(ContentStats stats) { + return viewOrNull(stats, Kind.LOWER_BOUND); + } + + /** Per-column upper bounds, or {@code null} if no column tracks an upper bound. */ + static <V> Map<Integer, V> upperBounds(ContentStats stats) { + return viewOrNull(stats, Kind.UPPER_BOUND); + } + + private static <V> Map<Integer, V> viewOrNull(ContentStats stats, Kind kind) { + return isEmpty(stats, kind) ? null : new ContentStatsBackedMap<>(stats, kind); + } + + private final ContentStats stats; + private final Kind kind; + private Set<Entry<Integer, V>> materialized; + + private ContentStatsBackedMap(ContentStats stats, Kind kind) { + this.stats = stats; + this.kind = kind; + } + + @Override + public V get(Object key) { + if (!(key instanceof Integer)) { + return null; + } + + FieldStats<?> fieldStats = stats.statsFor((Integer) key); + if (fieldStats == null) { + return null; + } + + return statValue(fieldStats, kind); + } + + @Override + public boolean containsKey(Object key) { + return get(key) != null; + } + + @Override + public boolean isEmpty() { + // avoid AbstractMap's default, which materializes entrySet() just to answer emptiness + return isEmpty(stats, kind); + } + + @Override + public Set<Entry<Integer, V>> entrySet() { Review Comment: entrySet() is the only method that has to materialize (it's a full projection), so its result is cached: AbstractMap routes size(), forEach(), toString(), and equals() through entrySet(), and without the cache any caller that does more than a single pass would rebuild the LinkedHashSet every time. get()/containsKey() stay pass-through and allocate nothing. It isn't equivalent to the old MetricsUtil.valueCounts(stats), which eagerly built and returned a full map on every call. Here the map is a lazy view: a caller that only does get() or a null check never materializes a set, and an empty metric returns null from an allocation-free scan rather than an empty map. That laziness, plus returning null instead of an empty map, is the reason for the class. ########## core/src/main/java/org/apache/iceberg/ContentStatsBackedMap.java: ########## @@ -0,0 +1,181 @@ +/* + * 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.iceberg; + +import java.nio.ByteBuffer; +import java.util.AbstractMap; +import java.util.Map; +import java.util.Set; +import org.apache.iceberg.relocated.com.google.common.collect.Sets; +import org.apache.iceberg.types.Conversions; +import org.apache.iceberg.types.Type; + +/** + * A lazy, read-only {@link Map} view of one stat across the columns of a {@link ContentStats}, + * keyed by field ID, mirroring the per-column stat maps on {@link ContentFile}. + */ +class ContentStatsBackedMap<V> extends AbstractMap<Integer, V> { + private enum Kind { + VALUE_COUNT, + NULL_VALUE_COUNT, + NAN_VALUE_COUNT, + LOWER_BOUND, + UPPER_BOUND + } + + /** Per-column value counts, or {@code null} if no column tracks the value count. */ + static <V> Map<Integer, V> valueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.VALUE_COUNT); + } + + /** Per-column null value counts, or {@code null} if no column tracks the null value count. */ + static <V> Map<Integer, V> nullValueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.NULL_VALUE_COUNT); + } + + /** Per-column NaN value counts, or {@code null} if no column tracks the NaN value count. */ + static <V> Map<Integer, V> nanValueCounts(ContentStats stats) { + return viewOrNull(stats, Kind.NAN_VALUE_COUNT); + } + + /** Per-column lower bounds, or {@code null} if no column tracks a lower bound. */ + static <V> Map<Integer, V> lowerBounds(ContentStats stats) { + return viewOrNull(stats, Kind.LOWER_BOUND); + } + + /** Per-column upper bounds, or {@code null} if no column tracks an upper bound. */ + static <V> Map<Integer, V> upperBounds(ContentStats stats) { + return viewOrNull(stats, Kind.UPPER_BOUND); + } + + private static <V> Map<Integer, V> viewOrNull(ContentStats stats, Kind kind) { + return isEmpty(stats, kind) ? null : new ContentStatsBackedMap<>(stats, kind); + } + + private final ContentStats stats; + private final Kind kind; + private Set<Entry<Integer, V>> materialized; + + private ContentStatsBackedMap(ContentStats stats, Kind kind) { + this.stats = stats; + this.kind = kind; + } + + @Override + public V get(Object key) { + if (!(key instanceof Integer)) { + return null; + } + + FieldStats<?> fieldStats = stats.statsFor((Integer) key); + if (fieldStats == null) { + return null; + } + + return statValue(fieldStats, kind); + } + + @Override + public boolean containsKey(Object key) { + return get(key) != null; + } + + @Override + public boolean isEmpty() { + // avoid AbstractMap's default, which materializes entrySet() just to answer emptiness + return isEmpty(stats, kind); + } + + @Override + public Set<Entry<Integer, V>> entrySet() { + if (materialized == null) { + Set<Entry<Integer, V>> entries = Sets.newLinkedHashSet(); + for (FieldStats<?> fieldStats : stats.fieldStats()) { + if (fieldStats != null) { + V value = statValue(fieldStats, kind); + if (value != null) { + entries.add(new SimpleImmutableEntry<>(fieldStats.fieldId(), value)); + } + } + } + + this.materialized = entries; + } + + return materialized; + } + + /** Returns whether no column contributes an entry for the metric, including for null stats. */ + private static boolean isEmpty(ContentStats stats, Kind kind) { + if (stats == null) { + return true; + } + + for (FieldStats<?> fieldStats : stats.fieldStats()) { Review Comment: isEmpty() is on the scan-planning's hot code path. A stream adds a Stream + lambda allocation per call, and ContentStats.fieldStats() returns an Iterable, so it would also need a Streams.stream(...) wrapper. The imperative loop short-circuits on the first contributing field and allocates nothing, so I'd prefer to keep it here. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
