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.metadata.bootstrap;
  
  import org.apache.kafka.metadata.util.BatchFileReader;
  import org.apache.kafka.metadata.util.BatchFileReader.BatchAndType;
  import org.apache.kafka.metadata.util.BatchFileWriter;
  import org.apache.kafka.server.common.ApiMessageAndVersion;
  import org.apache.kafka.server.common.MetadataVersion;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  
  import static java.nio.file.StandardCopyOption.ATOMIC_MOVE;
  import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
  
  /**
   * A read-only class that holds the controller bootstrap metadata. A file named "bootstrap.checkpoint" is used and the
   * format is the same as a KRaft snapshot.
   */
  public class BootstrapDirectory {
      public static final String BINARY_BOOTSTRAP_FILENAME = "bootstrap.checkpoint";
  
      private final String directoryPath;
  
      /**
       * Create a new BootstrapDirectory object.
       *
       * @param directoryPath     The path to the directory with the bootstrap file.
       */
      public BootstrapDirectory(
          String directoryPath
      ) {
          this.directoryPath = Objects.requireNonNull(directoryPath);
      }
  
      public BootstrapMetadata read() throws Exception {
          Path path = Paths.get(directoryPath);
          if (!Files.isDirectory(path)) {
              if (Files.exists(path)) {
                  throw new RuntimeException("Path " + directoryPath + " exists, but is not " +
                          "a directory.");
              } else {
                  throw new RuntimeException("No such directory as " + directoryPath);
              }
          }
          Path binaryBootstrapPath = Paths.get(directoryPath, BINARY_BOOTSTRAP_FILENAME);
          if (!Files.exists(binaryBootstrapPath)) {
              return readFromConfiguration();
          } else {
              return readFromBinaryFile(binaryBootstrapPath.toString());
          }
      }
  
      BootstrapMetadata readFromConfiguration() {
          return BootstrapMetadata.fromVersion(MetadataVersion.latestProduction(), "the default bootstrap");
      }
  
      BootstrapMetadata readFromBinaryFile(String binaryPath) throws Exception {
          List<ApiMessageAndVersion> records = new ArrayList<>();
          try (BatchFileReader reader = new BatchFileReader.Builder().
                  setPath(binaryPath).build()) {
              while (reader.hasNext()) {
                  BatchAndType batchAndType = reader.next();
                  if (!batchAndType.isControl()) {
                      records.addAll(batchAndType.batch().records());
                  }
              }
          }
          return BootstrapMetadata.fromRecords(Collections.unmodifiableList(records),
                  "the binary bootstrap metadata file: " + binaryPath);
      }
  
      public void writeBinaryFile(BootstrapMetadata bootstrapMetadata) throws IOException {
          if (!Files.isDirectory(Paths.get(directoryPath))) {
              throw new RuntimeException("No such directory as " + directoryPath);
          }
          Path tempPath = Paths.get(directoryPath, BINARY_BOOTSTRAP_FILENAME + ".tmp");
          Files.deleteIfExists(tempPath);
          try {
              try (BatchFileWriter writer = BatchFileWriter.open(tempPath)) {
                  for (ApiMessageAndVersion message : bootstrapMetadata.records()) {
                      writer.append(message);
                  }
              }
  
              Files.move(
                  tempPath,
                  Paths.get(directoryPath, BINARY_BOOTSTRAP_FILENAME),
                  ATOMIC_MOVE, REPLACE_EXISTING
              );
          } finally {
              Files.deleteIfExists(tempPath);
          }
      }
  }
  