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.api;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.List;
  import java.util.concurrent.CompletableFuture;
  import org.apache.bookkeeper.common.annotation.InterfaceAudience.Public;
  import org.apache.bookkeeper.common.annotation.InterfaceStability.Evolving;
  import org.apache.bookkeeper.common.concurrent.FutureUtils;
  import org.apache.distributedlog.AppendOnlyStreamReader;
  import org.apache.distributedlog.AppendOnlyStreamWriter;
  import org.apache.distributedlog.DLSN;
  import org.apache.distributedlog.LogRecordWithDLSN;
  import org.apache.distributedlog.LogSegmentMetadata;
  import org.apache.distributedlog.api.subscription.SubscriptionsStore;
  import org.apache.distributedlog.bk.LedgerMetadata;
  import org.apache.distributedlog.callback.LogSegmentListener;
  import org.apache.distributedlog.io.AsyncCloseable;
  import org.apache.distributedlog.namespace.NamespaceDriver;
  
  /**
   * A DistributedLogManager is responsible for managing a single place of storing
   * edit logs. It may correspond to multiple files, a backup node, etc.
   * Even when the actual underlying storage is rolled, or failed and restored,
   * each conceptual place of storage corresponds to exactly one instance of
   * this class, which is created when the EditLog is first opened.
   */
  @Public
  @Evolving
  public interface DistributedLogManager extends AsyncCloseable, Closeable {
  
      /**
       * Get the name of the stream managed by this log manager.
       * @return streamName
       */
      String getStreamName();
  
      /**
       * Get the namespace driver used by this manager.
       *
       * @return the namespace driver
       */
      NamespaceDriver getNamespaceDriver();
  
      //
      // Log Segment Related Operations
      //
  
      /**
       * Get log segments.
       *
       * @return log segments
       * @throws IOException
       */
      List<LogSegmentMetadata> getLogSegments() throws IOException;
  
  
      /**
       * Get the log segments asynchronously.
       *
       * @return the log segments
       */
      CompletableFuture<List<LogSegmentMetadata>> getLogSegmentsAsync();
  
      /**
       * Register <i>listener</i> on log segment updates of this stream.
       *
       * @param listener
       *          listener to receive update log segment list.
       */
      void registerListener(LogSegmentListener listener) throws IOException;
  
      /**
       * Unregister <i>listener</i> on log segment updates from this stream.
       *
       * @param listener
       *          listener to receive update log segment list.
       */
      void unregisterListener(LogSegmentListener listener);
  
      //
      // Writer & Reader Operations
      //
  
      /**
       * Open async log writer to write records to the log stream.
       *
       * @return result represents the open result
       */
      CompletableFuture<AsyncLogWriter> openAsyncLogWriter();
  
      /**
       * Open async log writer to write records to the log stream.
       * Provided metadata will be attached to the underlying BookKeeper ledgers.
       *
       * @param ledgerMetadata
       * @return result represents the open result
       */
      default CompletableFuture<AsyncLogWriter> openAsyncLogWriter(LedgerMetadata ledgerMetadata) {
          return FutureUtils.exception(new UnsupportedOperationException());
      }
  
      /**
       * Open sync log writer to write records to the log stream.
       *
       * @return sync log writer
       * @throws IOException when fails to open a sync log writer.
       */
      LogWriter openLogWriter() throws IOException;
  
      /**
       * Open sync log writer to write records to the log stream.
       * Provided metadata will be attached to the underlying BookKeeper ledgers.
       *
       * @param ledgerMetadata
       * @return sync log writer
       * @throws IOException when fails to open a sync log writer.
       */
      default LogWriter openLogWriter(LedgerMetadata ledgerMetadata) throws IOException {
          throw new UnsupportedOperationException();
      }
  
      /**
       * Begin writing to the log stream identified by the name.
       *
       * @return the writer interface to generate log records
       * @Deprecated since 0.5.0, in favor of using {@link #openLogWriter()}
       */
      LogWriter startLogSegmentNonPartitioned() throws IOException;
  
      /**
       * Begin writing to the log stream identified by the name.
       *
       * @return the writer interface to generate log records
       * @Deprecated since 0.5.0, in favor of using {@link #openAsyncLogWriter()}
       */
      AsyncLogWriter startAsyncLogSegmentNonPartitioned() throws IOException;
  
      /**
       * Open an sync log reader to read records from a log starting from <code>fromTxnId</code>.
       *
       * @param fromTxnId
       *          transaction id to start reading from
       * @return sync log reader
       */
      LogReader openLogReader(long fromTxnId) throws IOException;
  
      /**
       * Open an async log reader to read records from a log starting from <code>fromDLSN</code>.
       *
       * @param fromDLSN
       *          dlsn to start reading from
       * @return async log reader
       */
      LogReader openLogReader(DLSN fromDLSN) throws IOException;
  
      /**
       * Open an async log reader to read records from a log starting from <code>fromTxnId</code>.
       *
       * @param fromTxnId
       *          transaction id to start reading from
       * @return async log reader
       */
      CompletableFuture<AsyncLogReader> openAsyncLogReader(long fromTxnId);
  
      /**
       * Open an async log reader to read records from a log starting from <code>fromDLSN</code>.
       *
       * @param fromDLSN
       *          dlsn to start reading from
       * @return async log reader
       */
      CompletableFuture<AsyncLogReader> openAsyncLogReader(DLSN fromDLSN);
  
      /**
       * Get the input stream starting with fromTxnId for the specified log.
       *
       * @param fromTxnId - the first transaction id we want to read
       * @return the stream starting with transaction fromTxnId
       * @throws IOException if a stream cannot be found.
       * @Deprecated since 0.5.0, in favor of using {@link #openLogReader(long)}
       */
      LogReader getInputStream(long fromTxnId)
          throws IOException;
  
      /**
       * Get the input stream starting with fromTxnId for the specified log.
       *
       * @param fromDLSN - the first DLSN we want to read
       * @return the stream starting with DLSN
       * @throws IOException if a stream cannot be found.
       * @Deprecated since 0.5.0, in favor of using {@link #openLogReader(DLSN)}
       */
      LogReader getInputStream(DLSN fromDLSN) throws IOException;
  
      /**
       * Get an async log reader to read records from a log starting from <code>fromTxnId</code>.
       *
       * @param fromTxnId
       *          transaction id to start reading from
       * @return async log reader
       * @throws IOException when fails to open an async log reader.
       * @see #openAsyncLogReader(long)
       * @Deprecated it is deprecated since 0.5.0, in favor of using {@link #openAsyncLogReader(long)}
       */
      AsyncLogReader getAsyncLogReader(long fromTxnId) throws IOException;
  
      /**
       * Get an async log reader to read records from a log starting from <code>fromDLSN</code>.
       *
       * @param fromDLSN
       *          dlsn to start reading from
       * @return async log reader
       * @throws IOException when fails to open an async log reader.
       * @see #openAsyncLogReader(DLSN)
       * @Deprecated it is deprecated since 0.5.0, in favor of using {@link #openAsyncLogReader(DLSN)}
       */
      AsyncLogReader getAsyncLogReader(DLSN fromDLSN) throws IOException;
  
      /**
       * Get a log reader with lock starting from <i>fromDLSN</i>.
       *
       * <p>If two readers tried to open using same subscriberId, one would succeed, while the other
       * will be blocked until it gets the lock.
       *
       * @param fromDLSN
       *          start dlsn
       * @return async log reader
       */
      CompletableFuture<AsyncLogReader> getAsyncLogReaderWithLock(DLSN fromDLSN);
  
      /**
       * Get a log reader with lock starting from <i>fromDLSN</i> and using <i>subscriberId</i>.
       *
       * <p>If two readers tried to open using same subscriberId, one would succeed, while the other
       * will be blocked until it gets the lock.
       *
       * @param fromDLSN
       *          start dlsn
       * @param subscriberId
       *          subscriber id
       * @return async log reader
       */
      CompletableFuture<AsyncLogReader> getAsyncLogReaderWithLock(DLSN fromDLSN, String subscriberId);
  
      /**
       * Get a log reader using <i>subscriberId</i> with lock. The reader will start reading from
       * its last commit position recorded in subscription store. If no last commit position found
       * in subscription store, it would start reading from head of the stream.
       *
       * <p>If the two readers tried to open using same subscriberId, one would succeed, while the other
       * will be blocked until it gets the lock.
       *
       * @param subscriberId
       *          subscriber id
       * @return async log reader
       */
      CompletableFuture<AsyncLogReader> getAsyncLogReaderWithLock(String subscriberId);
  
      //
      // Stream writer and reader
      //
  
      /**
       * Begin appending to the end of the log stream which is being treated as a sequence of bytes.
       *
       * @return the writer interface to generate log records
       */
      AppendOnlyStreamWriter getAppendOnlyStreamWriter() throws IOException;
  
      /**
       * Get a reader to read a log stream as a sequence of bytes.
       *
       * @return the writer interface to generate log records
       */
      AppendOnlyStreamReader getAppendOnlyStreamReader() throws IOException;
  
      //
      // Metadata Operations:
      //
      // - retrieve head or tail records
      // - get log record count
      // - delete logs
      // - recover logs
      //
  
      /**
       * Get the {@link DLSN} of first log record whose transaction id is not less than <code>transactionId</code>.
       *
       * @param transactionId
       *          transaction id
       * @return dlsn of first log record whose transaction id is not less than transactionId.
       */
      CompletableFuture<DLSN> getDLSNNotLessThanTxId(long transactionId);
  
      /**
       * Get the last log record in the stream.
       *
       * @return the last log record in the stream
       * @throws IOException if a stream cannot be found.
       */
      LogRecordWithDLSN getLastLogRecord()
          throws IOException;
  
      /**
       * Get Latest log record with DLSN in the log - async.
       *
       * @return latest log record with DLSN
       */
      CompletableFuture<LogRecordWithDLSN> getLastLogRecordAsync();
  
      /**
       * Get the first log record in the stream.
       *
       * @return the first log record in the stream
       * @throws IOException if a stream cannot be found.
       */
      LogRecordWithDLSN getFirstLogRecord()
          throws IOException;
  
      /**
       * Get first log record with DLSN in the log - async.
       *
       * @return latest log record with DLSN
       */
      CompletableFuture<LogRecordWithDLSN> getFirstLogRecordAsync();
  
      /**
       * Get the earliest Transaction Id available in the log.
       *
       * @return earliest transaction id
       * @throws IOException
       */
      long getFirstTxId() throws IOException;
  
      /**
       * Get Latest Transaction Id in the log.
       *
       * @return latest transaction id
       * @throws IOException
       */
      long getLastTxId() throws IOException;
  
      /**
       * Get Latest Transaction Id in the log - async.
       *
       * @return latest transaction id
       */
      CompletableFuture<Long> getLastTxIdAsync();
  
      /**
       * Get first DLSN in the log.
       *
       * @return first dlsn in the stream
       */
      CompletableFuture<DLSN> getFirstDLSNAsync();
  
      /**
       * Get Latest DLSN in the log.
       *
       * @return last dlsn
       * @throws IOException
       */
      DLSN getLastDLSN() throws IOException;
  
      /**
       * Get Latest DLSN in the log - async.
       *
       * @return latest transaction id
       */
      CompletableFuture<DLSN> getLastDLSNAsync();
  
      /**
       * Get the number of log records in the active portion of the log.
       * Any log segments that have already been truncated will not be included
       *
       * @return number of log records
       * @throws IOException
       */
      long getLogRecordCount() throws IOException;
  
      /**
       * Get the number of log records in the active portion of the log - async.
       * Any log segments that have already been truncated will not be included
       *
       * @return future number of log records
       * @throws IOException
       */
      CompletableFuture<Long> getLogRecordCountAsync(DLSN beginDLSN);
  
      /**
       * Run recovery on the log.
       *
       * @throws IOException
       */
      void recover() throws IOException;
  
      /**
       * Check if an end of stream marker was added to the stream.
       * A stream with an end of stream marker cannot be appended to
       *
       * @return true if the marker was added to the stream, false otherwise
       * @throws IOException
       */
      boolean isEndOfStreamMarked() throws IOException;
  
      /**
       * Delete the log.
       *
       * @throws IOException if the deletion fails
       * @Deprecated since 0.5.0, in favor of using
       *             {@link org.apache.distributedlog.api.namespace.Namespace#deleteLog(String)}
       */
      void delete() throws IOException;
  
      /**
       * The DistributedLogManager may archive/purge any logs for transactionId
       * less than or equal to minImageTxId.
       * This is to be used only when the client explicitly manages deletion. If
       * the cleanup policy is based on sliding time window, then this method need
       * not be called.
       *
       * @param minTxIdToKeep the earliest txid that must be retained
       * @throws IOException if purging fails
       */
      void purgeLogsOlderThan(long minTxIdToKeep) throws IOException;
  
      /**
       * Get the subscriptions store provided by the distributedlog manager.
       *
       * @return subscriptions store manages subscriptions for current stream.
       */
      SubscriptionsStore getSubscriptionsStore();
  
  }
  