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.Closeable;
  import java.util.List;
  import java.util.concurrent.CompletableFuture;
  import org.apache.bookkeeper.versioning.Version;
  import org.apache.bookkeeper.versioning.Versioned;
  import org.apache.distributedlog.LogSegmentMetadata;
  import org.apache.distributedlog.callback.LogSegmentNamesListener;
  import org.apache.distributedlog.metadata.LogMetadata;
  import org.apache.distributedlog.metadata.LogMetadataForWriter;
  import org.apache.distributedlog.util.Transaction;
  import org.apache.distributedlog.util.Transaction.OpListener;
  
  
  /**
   * Interface for log segment metadata store. All operations that modify log segments should
   * be executed under a {@link Transaction}.
   */
  @Beta
  public interface LogSegmentMetadataStore extends Closeable {
  
      /**
       * Start the transaction on changing log segment metadata store.
       *
       * @return transaction of the log segment metadata store.
       */
      Transaction<Object> transaction();
  
      // The reason to keep storing log segment sequence number & log record transaction id
      // in this log segment metadata store interface is to share the transaction that used
      // to start/complete log segment. It is a bit hard to separate them out right now.
  
      /**
       * Store the maximum log segment sequence number on <code>path</code>.
       *
       * @param txn
       *          transaction to execute for storing log segment sequence number.
       * @param logMetadata
       *          metadata of the log stream
       * @param sequenceNumber
       *          log segment sequence number to store
       * @param listener
       *          listener on the result to this operation
       */
      void storeMaxLogSegmentSequenceNumber(Transaction<Object> txn,
                                            LogMetadata logMetadata,
                                            Versioned<Long> sequenceNumber,
                                            OpListener<Version> listener);
  
      /**
       * Store the maximum transaction id for <code>path</code>.
       *
       * @param txn
       *          transaction to execute for storing transaction id
       * @param logMetadata
       *          metadata of the log stream
       * @param transactionId
       *          transaction id to store
       * @param listener
       *          listener on the result to this operation
       */
      void storeMaxTxnId(Transaction<Object> txn,
                         LogMetadataForWriter logMetadata,
                         Versioned<Long> transactionId,
                         OpListener<Version> listener);
  
      /**
       * Create a log segment <code>segment</code> under transaction <code>txn</code>.
       *
       * <p>NOTE: this operation shouldn't be a blocking call. and it shouldn't execute the operation
       *       immediately. the operation should be executed via {@link Transaction#execute()}</p>
       *
       * @param txn
       *          transaction to execute for this operation
       * @param segment
       *          segment to create
       * @param opListener
       *          the listener on the operation result
       */
      void createLogSegment(Transaction<Object> txn,
                            LogSegmentMetadata segment,
                            OpListener<Void> opListener);
  
      /**
       * Delete a log segment <code>segment</code> under transaction <code>txn</code>.
       *
       * <p>NOTE: this operation shouldn't be a blocking call. and it shouldn't execute the operation
       *       immediately. the operation should be executed via {@link Transaction#execute()}</p>
       *
       * @param txn
       *          transaction to execute for this operation
       * @param segment
       *          segment to delete
       */
      void deleteLogSegment(Transaction<Object> txn,
                            LogSegmentMetadata segment,
                            OpListener<Void> opListener);
  
      /**
       * Update a log segment <code>segment</code> under transaction <code>txn</code>.
       *
       * <p>NOTE: this operation shouldn't be a blocking call. and it shouldn't execute the operation
       *       immediately. the operation should be executed via {@link Transaction#execute()}</p>
       *
       * @param txn
       *          transaction to execute for this operation
       * @param segment
       *          segment to update
       */
      void updateLogSegment(Transaction<Object> txn, LogSegmentMetadata segment);
  
      /**
       * Retrieve the log segment associated <code>path</code>.
       *
       * @param logSegmentPath
       *          path to store log segment metadata
       * @return future of the retrieved log segment metadata
       */
      CompletableFuture<LogSegmentMetadata> getLogSegment(String logSegmentPath);
  
      /**
       * Retrieve the list of log segments under <code>logSegmentsPath</code> and register a <i>listener</i>
       * for subsequent changes for the list of log segments.
       *
       * @param logSegmentsPath
       *          path to store list of log segments
       * @param listener
       *          log segment listener on log segment changes
       * @return future of the retrieved list of log segment names
       */
      CompletableFuture<Versioned<List<String>>> getLogSegmentNames(String logSegmentsPath,
                                                                    LogSegmentNamesListener listener);
  
      /**
       * Unregister a log segment <code>listener</code> on log segment changes under <code>logSegmentsPath</code>.
       *
       * @param logSegmentsPath
       *          log segments path
       * @param listener
       *          log segment listener on log segment changes
       */
      void unregisterLogSegmentListener(String logSegmentsPath,
                                        LogSegmentNamesListener listener);
  }
  