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.DLSN;
  import org.apache.distributedlog.LogRecord;
  import org.apache.distributedlog.exceptions.BKTransmitException;
  import org.apache.distributedlog.exceptions.LockingException;
  import org.apache.distributedlog.io.AsyncAbortable;
  import org.apache.distributedlog.io.AsyncCloseable;
  
  /**
   * An interface class to write log records into a log segment.
   */
  @Beta
  public interface LogSegmentWriter extends AsyncCloseable, AsyncAbortable {
  
      /**
       * Get the unique log segment id.
       *
       * @return log segment id.
       */
      long getLogSegmentId();
  
      /**
       * Write a log record to a log segment.
       *
       * @param record single log record
       * @return a future representing write result. A {@link DLSN} is returned if write succeeds,
       *         otherwise, exceptions are returned.
       * @throws org.apache.distributedlog.exceptions.LogRecordTooLongException if log record is too long
       * @throws org.apache.distributedlog.exceptions.InvalidEnvelopedEntryException on invalid enveloped entry
       * @throws LockingException if failed to acquire lock for the writer
       * @throws BKTransmitException if failed to transmit data to bk
       * @throws org.apache.distributedlog.exceptions.WriteException if failed to write to bk
       */
      CompletableFuture<DLSN> asyncWrite(LogRecord record);
  
      /**
       * This isn't a simple synchronous version of {@code asyncWrite}. It has different semantic.
       * This method only writes data to the buffer and flushes buffer if needed.
       * TODO: we should remove this method. when we rewrite synchronous writer based on asynchronous writer,
       *       since this is the semantic needed to be provided in higher level but just calling write & flush.
       *
       * @param record single log record
       * @throws IOException when tried to flush the buffer.
       * @see LogSegmentWriter#asyncWrite(LogRecord)
       */
      void write(LogRecord record) throws IOException;
  
      /**
       * Transmit the buffered data and wait for it being persisted and return the last acknowledged
       * transaction id.
       *
       * @return future representing the transmit result with last acknowledged transaction id.
       */
      CompletableFuture<Long> flush();
  
      /**
       * Commit the current acknowledged data. It is the consequent operation of {@link #flush()},
       * which makes all the acknowledged data visible to
       *
       * @return future representing the commit result.
       */
      CompletableFuture<Long> commit();
  
  }
  