rdblue commented on code in PR #6706: URL: https://github.com/apache/iceberg/pull/6706#discussion_r1098064310
########## core/src/main/java/org/apache/iceberg/SnapshotOperations.java: ########## @@ -0,0 +1,263 @@ +/* + * 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.io.Serializable; +import java.util.Collection; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.function.Function; +import java.util.stream.Collectors; +import org.apache.iceberg.exceptions.ValidationException; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.iceberg.relocated.com.google.common.collect.Maps; +import org.apache.iceberg.relocated.com.google.common.collect.Sets; +import org.apache.iceberg.util.SerializableMap; +import org.apache.iceberg.util.SerializableSupplier; + +/** + * SnapshotOperations abstracts access to snapshots for table metadata. This allows a subset of + * snapshots/refs to be loaded initially for operations that do not require all to be present (e.g. + * table scans of the current snapshot). + * + * <p>In the event that snapshots/refs need to be accessed, the provided supplier will be invoked, + * which must provide all addressable snapshots for the table. + */ +class SnapshotOperations implements Serializable { + private List<Snapshot> snapshots; + private final SerializableSupplier<List<Snapshot>> snapshotsSupplier; + private Map<Long, Snapshot> snapshotsById; + private Map<String, SnapshotRef> refs; + private final SerializableSupplier<Map<String, SnapshotRef>> refsSupplier; + private boolean loaded; + + private SnapshotOperations( + List<Snapshot> snapshots, + SerializableSupplier<List<Snapshot>> snapshotsSupplier, + Map<String, SnapshotRef> refs, + SerializableSupplier<Map<String, SnapshotRef>> refsSupplier) { + this.snapshots = ImmutableList.copyOf(snapshots); + this.snapshotsSupplier = snapshotsSupplier; + this.refs = SerializableMap.copyOf(refs); + this.refsSupplier = refsSupplier; + + this.snapshotsById = indexSnapshotsById(snapshots); + } + + List<Snapshot> snapshots() { + ensureLoaded(); + + return snapshots; + } + + Snapshot snapshot(long id) { + if (!snapshotsById.containsKey(id)) { + ensureLoaded(); + } + + return snapshotsById.get(id); + } + + boolean contains(long id) { + if (!snapshotsById.containsKey(id)) { + ensureLoaded(); + } + + return snapshotsById.containsKey(id); + } + + Map<String, SnapshotRef> refs() { + return refs; + } + + SnapshotRef ref(String name) { + return refs.get(name); + } + + private void ensureLoaded() { + if (!loaded && snapshotsSupplier != null) { + this.snapshots = ImmutableList.copyOf(snapshotsSupplier.get()); + this.snapshotsById = indexSnapshotsById(snapshots); + } + + if (!loaded && refsSupplier != null) { + this.refs = SerializableMap.copyOf(refsSupplier.get()); + } + + loaded = true; + } + + void validate(long currentSnapshotId, long lastSequenceNumber) { + validateSnapshots(lastSequenceNumber); + validateRefs(currentSnapshotId); + } + + private void validateSnapshots(long lastSequenceNumber) { + for (Snapshot snap : snapshots) { + ValidationException.check( + snap.sequenceNumber() <= lastSequenceNumber, + "Invalid snapshot with sequence number %s greater than last sequence number %s", + snap.sequenceNumber(), + lastSequenceNumber); + } + } + + private void validateRefs(long currentSnapshotId) { + for (SnapshotRef ref : refs.values()) { + Preconditions.checkArgument( + snapshotsById.containsKey(ref.snapshotId()), + "Snapshot for reference %s does not exist in the existing snapshots list", + ref); + } + + SnapshotRef main = refs.get(SnapshotRef.MAIN_BRANCH); + if (currentSnapshotId != -1) { + Preconditions.checkArgument( + main == null || currentSnapshotId == main.snapshotId(), + "Current snapshot ID does not match main branch (%s != %s)", + currentSnapshotId, + main != null ? main.snapshotId() : null); + } else { + Preconditions.checkArgument( + main == null, "Current snapshot is not set, but main branch exists: %s", main); + } + } + + private static Map<Long, Snapshot> indexSnapshotsById(List<Snapshot> snapshots) { + return SerializableMap.copyOf( + snapshots.stream().collect(Collectors.toMap(Snapshot::snapshotId, Function.identity()))); + } + + public static Builder buildFrom(SnapshotOperations base) { + return new Builder(base); + } + + public static Builder buildFromEmpty() { + return new Builder(); + } + + public static SnapshotOperations empty() { + return SnapshotOperations.buildFromEmpty().build(); + } + + static class Builder { + private List<Snapshot> snapshots; + private SerializableSupplier<List<Snapshot>> snapshotsSupplier; + private final Map<Long, Snapshot> snapshotsById; + private Map<String, SnapshotRef> refs; + private SerializableSupplier<Map<String, SnapshotRef>> refsSupplier; + + Builder() { + this.snapshots = Lists.newArrayList(); + this.refs = Maps.newHashMap(); + + this.snapshotsById = Maps.newHashMap(); + } + + Builder(SnapshotOperations base) { + this.snapshots = Lists.newArrayList(base.snapshots); + this.snapshotsSupplier = base.snapshotsSupplier; + this.refs = Maps.newHashMap(base.refs); + this.refsSupplier = base.refsSupplier; + + this.snapshotsById = indexSnapshotsById(snapshots); + } + + Builder snapshots(List<Snapshot> snapshots1) { Review Comment: We would normally use `newSnapshots` instead of `snapshots1`. -- This is an automated message from the Apache Git Service. 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