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.distributedlog.logsegment;
  
  import com.google.common.annotations.Beta;
  import java.io.IOException;
  import java.util.concurrent.CompletableFuture;
  import org.apache.distributedlog.LogSegmentMetadata;
  import org.apache.distributedlog.bk.LedgerMetadata;
  import org.apache.distributedlog.config.DynamicDistributedLogConfiguration;
  import org.apache.distributedlog.metadata.LogMetadataForWriter;
  import org.apache.distributedlog.util.Allocator;
  
  
  /**
   * Log Segment Store to read log segments.
   */
  @Beta
  public interface LogSegmentEntryStore {
  
      /**
       * Delete the actual log segment from the entry store.
       *
       * @param segment log segment metadata
       * @return future represent the delete result
       */
      CompletableFuture<LogSegmentMetadata> deleteLogSegment(LogSegmentMetadata segment);
  
      /**
       * Create a new log segment allocator for allocating log segment entry writers.
       *
       * @param metadata the metadata for the log stream
       * @return future represent the log segment allocator
       */
      Allocator<LogSegmentEntryWriter, Object> newLogSegmentAllocator(
              LogMetadataForWriter metadata,
              DynamicDistributedLogConfiguration dynConf) throws IOException;
  
      /**
       * Create a new log segment allocator for allocating log segment entry writers.
       *
       * @param metadata the metadata for the log stream
       * @param ledgerMetadata metadata to be attached to underlying ledgers
       * @return future represent the log segment allocator
       */
      default Allocator<LogSegmentEntryWriter, Object> newLogSegmentAllocator(
              LogMetadataForWriter metadata,
              DynamicDistributedLogConfiguration dynConf,
              LedgerMetadata ledgerMetadata) throws IOException {
          throw new UnsupportedOperationException();
      }
  
      /**
       * Open the reader for reading data to the log <i>segment</i>.
       *
       * @param segment the log <i>segment</i> to read data from
       * @param startEntryId the start entry id
       * @return future represent the opened reader
       */
      CompletableFuture<LogSegmentEntryReader> openReader(LogSegmentMetadata segment,
                                               long startEntryId);
  
      /**
       * Open the reader for reading entries from a random access log <i>segment</i>.
       *
       * @param segment the log <i>segment</i> to read entries from
       * @param fence the flag to fence log segment
       * @return future represent the opened random access reader
       */
      CompletableFuture<LogSegmentRandomAccessEntryReader> openRandomAccessReader(LogSegmentMetadata segment,
                                                                       boolean fence);
  }
  