[Gemini] Add ExpireSnapshots maintenance operation to Iceberg IO

sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/maintenance/DeleteFilesDoFn.java

@@ -0,0 +1,182 @@
+/*
+ * 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.maintenance;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import org.apache.beam.sdk.io.iceberg.IcebergCatalogConfig;
+import org.apache.beam.sdk.io.iceberg.IcebergUtils;
+import org.apache.beam.sdk.io.iceberg.TableCache;
+import org.apache.beam.sdk.metrics.Metrics;
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.util.ShardedKey;
+import org.apache.beam.sdk.values.KV;
+import org.apache.iceberg.Table;
+import org.apache.iceberg.exceptions.NotFoundException;
+import org.apache.iceberg.io.BulkDeletionFailureException;
+import org.apache.iceberg.io.FileIO;
+import org.apache.iceberg.io.SupportsBulkOperations;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Worker DoFn that deletes batched unreferenced files from storage and emits partial deletion
+ * metrics.
+ */
+public class DeleteFilesDoFn
+    extends DoFn<KV<ShardedKey<String>, Iterable<FileInfo>>, ExpireSnapshotsResult> {
+
+  private static final Logger LOG = LoggerFactory.getLogger(DeleteFilesDoFn.class);
+
+  private final IcebergCatalogConfig catalogConfig;
+  private final ExpireSnapshots.Configuration config;
+
+  public DeleteFilesDoFn(IcebergCatalogConfig catalogConfig, ExpireSnapshots.Configuration config) {
+    this.catalogConfig = catalogConfig;
+    this.config = config;
+  }
+
+  @ProcessElement
+  public void processElement(
+      @Element KV<ShardedKey<String>, Iterable<FileInfo>> element,
+      OutputReceiver<ExpireSnapshotsResult> out) {
+    String tableIdString = element.getKey().getKey();
+    if (tableIdString == null || tableIdString.isEmpty()) {
+      return;
+    }
+
+    Table table =
+        TableCache.getAndRefreshIfStale(
+            catalogConfig, IcebergUtils.parseTableIdentifier(tableIdString));
+    FileIO io = table.io();
+
+    List<FileInfo> fileList = new ArrayList<>();
+    List<String> paths = new ArrayList<>();
+    for (FileInfo file : element.getValue()) {
+      fileList.add(file);
+      paths.add(file.getPath());
+    }
+
+    if (paths.isEmpty()) {
+      return;
+    }
+
+    Set<String> failedPaths = Collections.emptySet();
+    if (config.cleanFiles()) {
+      failedPaths = deletePaths(io, paths);
+      if (!failedPaths.isEmpty()) {
+        Metrics.counter(DeleteFilesDoFn.class, "failed_file_deletions").inc(failedPaths.size());
+      }
+    } else {
+      LOG.info(
+          ExpireSnapshots.PREFIX
+              + "Dry run enabled (cleanFiles=false); skipping physical deletion of {} file(s).",
+          paths.size());
+    }
+
+    long dataCount = 0;
+    long posDeleteCount = 0;
+    long eqDeleteCount = 0;
+    long manifestCount = 0;
+    long manifestListCount = 0;
+    long statsCount = 0;
+
+    for (FileInfo file : fileList) {
+      if (failedPaths.contains(file.getPath())) {
+        continue;
+      }
+      switch (file.fileCategory()) {
+        case DATA:
+          dataCount++;
+          break;
+        case POSITION_DELETES:
+          posDeleteCount++;
+          break;
+        case EQUALITY_DELETES:
+          eqDeleteCount++;
+          break;
+        case MANIFEST:
+          manifestCount++;
+          break;
+        case MANIFEST_LIST:
+          manifestListCount++;
+          break;
+        case STATISTICS:
+          statsCount++;
+          break;
+      }
+    }
+
+    out.output(
+        ExpireSnapshotsResult.builder()
+            .setDeletedDataFilesCount(dataCount)
+            .setDeletedPositionDeleteFilesCount(posDeleteCount)
+            .setDeletedEqualityDeleteFilesCount(eqDeleteCount)
+            .setDeletedManifestsCount(manifestCount)
+            .setDeletedManifestListsCount(manifestListCount)
+            .setDeletedStatisticsFilesCount(statsCount)
+            .build());
+  }
+
+  /**
+   * Deletes {@code paths} using {@link SupportsBulkOperations} when supported by {@link FileIO},
+   * falling back to per-file deletion. Silently ignores {@link NotFoundException}.
+   *
+   * @return set of paths that failed to be deleted
+   */
+  static Set<String> deletePaths(FileIO io, List<String> paths) {
+    Set<String> failedPaths = new HashSet<>();
+    if (paths.isEmpty()) {
+      return failedPaths;
+    }
+    if (io instanceof SupportsBulkOperations) {
+      try {
+        ((SupportsBulkOperations) io).deleteFiles(paths);
+        return failedPaths;
+      } catch (BulkDeletionFailureException e) {
+        LOG.warn(
+            ExpireSnapshots.PREFIX
+                + "Bulk delete failed for {} of {} files. Retrying individually.",
+            e.numberFailedObjects(),
+            paths.size(),
+            e);
+      } catch (RuntimeException e) {
+        LOG.warn(
+            ExpireSnapshots.PREFIX
+                + "Bulk delete raised non-bulk exception; falling back to per-file deletion.",
+            e);
+      }
+    }
+
+    for (String path : paths) {
+      try {
+        io.deleteFile(path);
+      } catch (NotFoundException e) {
+        LOG.debug(
+            ExpireSnapshots.PREFIX + "File {} not found during deletion (already removed).", path);
+      } catch (Exception e) {
+        LOG.warn(ExpireSnapshots.PREFIX + "Failed to delete file {}.", path, e);
+        failedPaths.add(path);
+      }
+    }
+    return failedPaths;
+  }
+}