content: /*
   * 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.snapshot;
  
  import org.apache.kafka.common.utils.BufferSupplier;
  import org.apache.kafka.common.utils.LogContext;
  import org.apache.kafka.common.utils.Utils;
  import org.apache.kafka.raft.KafkaRaftClient;
  import org.apache.kafka.raft.internals.IdentitySerde;
  import org.apache.kafka.server.common.OffsetAndEpoch;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.ByteBuffer;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.text.NumberFormat;
  import java.util.Optional;
  
  public final class Snapshots {
      private static final Logger log = LoggerFactory.getLogger(Snapshots.class);
      public static final String SUFFIX = ".checkpoint";
      private static final String PARTIAL_SUFFIX = String.format("%s.part", SUFFIX);
      public static final String DELETE_SUFFIX = String.format("%s.deleted", SUFFIX);
  
      private static final NumberFormat OFFSET_FORMATTER = NumberFormat.getInstance();
      private static final NumberFormat EPOCH_FORMATTER = NumberFormat.getInstance();
  
      private static final int OFFSET_WIDTH = 20;
      private static final int EPOCH_WIDTH = 10;
  
      public static final OffsetAndEpoch BOOTSTRAP_SNAPSHOT_ID = new OffsetAndEpoch(0, 0);
  
      static {
          OFFSET_FORMATTER.setMinimumIntegerDigits(OFFSET_WIDTH);
          OFFSET_FORMATTER.setGroupingUsed(false);
  
          EPOCH_FORMATTER.setMinimumIntegerDigits(EPOCH_WIDTH);
          EPOCH_FORMATTER.setGroupingUsed(false);
      }
  
      static Path snapshotDir(Path logDir) {
          return logDir;
      }
  
      public static String filenameFromSnapshotId(OffsetAndEpoch snapshotId) {
          return String.format("%s-%s", OFFSET_FORMATTER.format(snapshotId.offset()), EPOCH_FORMATTER.format(snapshotId.epoch()));
      }
  
      static Path moveRename(Path source, OffsetAndEpoch snapshotId) {
          return source.resolveSibling(filenameFromSnapshotId(snapshotId) + SUFFIX);
      }
  
      static Path deleteRenamePath(Path source, OffsetAndEpoch snapshotId) {
          return source.resolveSibling(filenameFromSnapshotId(snapshotId) + DELETE_SUFFIX);
      }
  
      public static Path snapshotPath(Path logDir, OffsetAndEpoch snapshotId) {
          return snapshotDir(logDir).resolve(filenameFromSnapshotId(snapshotId) + SUFFIX);
      }
  
      public static Path createTempFile(Path logDir, OffsetAndEpoch snapshotId) {
          Path dir = snapshotDir(logDir);
  
          try {
              // Create the snapshot directory if it doesn't exist
              Files.createDirectories(dir);
              String prefix = String.format("%s-", filenameFromSnapshotId(snapshotId));
              return Files.createTempFile(dir, prefix, PARTIAL_SUFFIX);
          } catch (IOException e) {
              throw new UncheckedIOException(
                  String.format("Error creating temporary file, logDir = %s, snapshotId = %s.",
                       dir.toAbsolutePath(), snapshotId), e);
          }
      }
  
      public static Optional<SnapshotPath> parse(Path path) {
          Path filename = path.getFileName();
          if (filename == null) {
              return Optional.empty();
          }
  
          String name = filename.toString();
  
          boolean partial = false;
          boolean deleted = false;
          if (name.endsWith(PARTIAL_SUFFIX)) {
              partial = true;
          } else if (name.endsWith(DELETE_SUFFIX)) {
              deleted = true;
          } else if (!name.endsWith(SUFFIX)) {
              return Optional.empty();
          }
  
          long endOffset = Long.parseLong(name.substring(0, OFFSET_WIDTH));
          int epoch = Integer.parseInt(
              name.substring(OFFSET_WIDTH + 1, OFFSET_WIDTH + EPOCH_WIDTH + 1)
          );
  
          return Optional.of(new SnapshotPath(path, new OffsetAndEpoch(endOffset, epoch), partial, deleted));
      }
  
      /**
       * Delete the snapshot from the filesystem.
       */
      public static boolean deleteIfExists(Path logDir, OffsetAndEpoch snapshotId) {
          Path immutablePath = snapshotPath(logDir, snapshotId);
          Path deletedPath = deleteRenamePath(immutablePath, snapshotId);
          try {
              boolean deleted = Files.deleteIfExists(immutablePath) | Files.deleteIfExists(deletedPath);
              if (deleted) {
                  log.info("Deleted snapshot files for snapshot {}.", snapshotId);
              } else {
                  log.info("Did not delete snapshot files for snapshot {} since they did not exist.", snapshotId);
              }
              return deleted;
          } catch (IOException e) {
              log.error("Error deleting snapshot files {} and {}", immutablePath, deletedPath, e);
              return false;
          }
      }
  
      /**
       * Mark a snapshot for deletion by renaming with the deleted suffix.
       *
       * @return the path of the snapshot marked for deletion (i.e. with .delete suffix)
       */
      public static Path markForDelete(Path logDir, OffsetAndEpoch snapshotId) {
          Path immutablePath = snapshotPath(logDir, snapshotId);
          Path deletedPath = deleteRenamePath(immutablePath, snapshotId);
          try {
              Utils.atomicMoveWithFallback(immutablePath, deletedPath, false);
              return deletedPath;
          } catch (IOException e) {
              throw new UncheckedIOException(
                  String.format(
                      "Error renaming snapshot file from %s to %s.",
                      immutablePath,
                      deletedPath
                  ),
                  e
              );
          }
      }
  
      public static long lastContainedLogTimestamp(RawSnapshotReader reader, LogContext logContext) {
          try (var bufferSupplier = new BufferSupplier.GrowableBufferSupplier();
               RecordsSnapshotReader<ByteBuffer> recordsSnapshotReader =
                  RecordsSnapshotReader.of(
                      reader,
                      IdentitySerde.INSTANCE,
                      bufferSupplier,
                      KafkaRaftClient.MAX_BATCH_SIZE_BYTES,
                      true,
                      logContext
                  )
          ) {
              return recordsSnapshotReader.lastContainedLogTimestamp();
          }
      }
  
      public static long lastContainedLogTimestamp(Path logDir, OffsetAndEpoch snapshotId, LogContext logContext) {
          try (FileRawSnapshotReader reader = FileRawSnapshotReader.open(logDir, snapshotId)) {
              return lastContainedLogTimestamp(reader, logContext);
          }
      }
  }
  