ahmedabu98 commented on code in PR #33504: URL: https://github.com/apache/beam/pull/33504#discussion_r2004411343
########## sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/TableCache.java: ########## @@ -0,0 +1,60 @@ +/* + * 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.io.iceberg; + +import java.util.concurrent.ExecutionException; +import java.util.concurrent.TimeUnit; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.Cache; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheBuilder; +import org.apache.iceberg.Table; +import org.apache.iceberg.catalog.Catalog; +import org.apache.iceberg.catalog.TableIdentifier; +import org.checkerframework.checker.nullness.qual.Nullable; + +/** Utility to fetch and cache Iceberg {@link Table}s. */ +class TableCache { + private static final Cache<TableIdentifier, Table> CACHE = + CacheBuilder.newBuilder().expireAfterWrite(3, TimeUnit.MINUTES).build(); Review Comment: Done ########## sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/WatchForSnapshots.java: ########## @@ -0,0 +1,191 @@ +/* + * 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.io.iceberg; + +import static org.apache.beam.sdk.transforms.Watch.Growth.PollResult; + +import java.util.ArrayList; +import java.util.List; +import java.util.stream.Collectors; +import org.apache.beam.sdk.coders.ListCoder; +import org.apache.beam.sdk.metrics.Counter; +import org.apache.beam.sdk.metrics.Gauge; +import org.apache.beam.sdk.metrics.Metrics; +import org.apache.beam.sdk.state.StateSpec; +import org.apache.beam.sdk.state.StateSpecs; +import org.apache.beam.sdk.state.ValueState; +import org.apache.beam.sdk.transforms.Create; +import org.apache.beam.sdk.transforms.DoFn; +import org.apache.beam.sdk.transforms.PTransform; +import org.apache.beam.sdk.transforms.ParDo; +import org.apache.beam.sdk.transforms.Watch; +import org.apache.beam.sdk.values.KV; +import org.apache.beam.sdk.values.PBegin; +import org.apache.beam.sdk.values.PCollection; +import org.apache.beam.sdk.values.TimestampedValue; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.MoreObjects; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Objects; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables; +import org.apache.iceberg.Snapshot; +import org.apache.iceberg.Table; +import org.checkerframework.checker.nullness.qual.Nullable; +import org.joda.time.Duration; +import org.joda.time.Instant; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Keeps watch over an Iceberg table and continuously outputs a range of snapshots, at the specified + * interval. + * + * <p>A downstream transform will create a list of read tasks for each range. + */ +class WatchForSnapshots extends PTransform<PBegin, PCollection<KV<String, List<SnapshotInfo>>>> { + private static final Logger LOG = LoggerFactory.getLogger(WatchForSnapshots.class); + private final Duration pollInterval; + private final IcebergScanConfig scanConfig; + + WatchForSnapshots(IcebergScanConfig scanConfig, Duration pollInterval) { + this.pollInterval = pollInterval; + this.scanConfig = scanConfig; + } + + @Override + public PCollection<KV<String, List<SnapshotInfo>>> expand(PBegin input) { + return input + .apply(Create.of(scanConfig.getTableIdentifier())) + .apply( + "Scan Table Snapshots", + Watch.growthOf(new SnapshotPollFn(scanConfig)) + .withPollInterval(pollInterval) + .withOutputCoder(ListCoder.of(SnapshotInfo.getCoder()))) + .apply("Persist Snapshot Progress", ParDo.of(new PersistSnapshotProgress())); + } + + /** + * Periodically scans the table for new snapshots, emitting a list for each new snapshot range. + * + * <p>This tracks progress locally but is not resilient to retries -- upon worker failure, it will + * restart from the initial starting strategy. Resilience is handled downstream by {@link + * PersistSnapshotProgress}. + */ + private static class SnapshotPollFn extends Watch.Growth.PollFn<String, List<SnapshotInfo>> { + private final IcebergScanConfig scanConfig; + private @Nullable Long fromSnapshotId; + + SnapshotPollFn(IcebergScanConfig scanConfig) { + this.scanConfig = scanConfig; + } + + @Override + public PollResult<List<SnapshotInfo>> apply(String tableIdentifier, Context c) { + // fetch a fresh table to catch new snapshots + Table table = + TableCache.getRefreshed(tableIdentifier, scanConfig.getCatalogConfig().catalog()); + + @Nullable Long userSpecifiedToSnapshot = ReadUtils.getToSnapshot(table, scanConfig); + boolean isComplete = userSpecifiedToSnapshot != null; + if (fromSnapshotId == null) { + // first scan, initialize starting point with user config + fromSnapshotId = ReadUtils.getFromSnapshotExclusive(table, scanConfig); + } + + Snapshot currentSnapshot = table.currentSnapshot(); + if (currentSnapshot == null || Objects.equal(currentSnapshot.snapshotId(), fromSnapshotId)) { + // no new snapshots since last poll. return empty result. + return getPollResult(null, isComplete); + } + + Long currentSnapshotId = currentSnapshot.snapshotId(); + // if no upper bound is specified, we poll up to the current snapshot + long toSnapshotId = MoreObjects.firstNonNull(userSpecifiedToSnapshot, currentSnapshotId); + + List<SnapshotInfo> snapshots = + ReadUtils.snapshotsBetween(table, tableIdentifier, fromSnapshotId, toSnapshotId); + + fromSnapshotId = currentSnapshotId; + return getPollResult(snapshots, isComplete); + } + + private PollResult<List<SnapshotInfo>> getPollResult( + @Nullable List<SnapshotInfo> snapshots, boolean isComplete) { + List<TimestampedValue<List<SnapshotInfo>>> timestampedSnapshots = new ArrayList<>(1); Review Comment: Done -- This is an automated message from the Apache Git Service. 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