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.beam.runners.dataflow.worker.util.common.worker;
  
  import java.io.IOException;
  
  /**
   * Abstract base class for Sinks.
   *
   * <p>A Sink is written to by getting a SinkWriter and adding values to it.
   *
   * @param <T> the type of the elements written to the sink
   */
  public abstract class Sink<T> {
  
    /** Returns a Writer that allows writing to this Sink. */
    public abstract SinkWriter<T> writer() throws IOException;
  
    /** Writes to a Sink. */
    public interface SinkWriter<ElemT> extends AutoCloseable {
      /** Adds a value to the sink. Returns the size in bytes of the data written. */
      public long add(ElemT value) throws IOException;
  
      /**
       * {@inheritDoc}
       *
       * <p>{@link #close()} will not be called after a call to {@link #abort()}
       */
      @Override
      public void close() throws IOException;
  
      /**
       * Aborts writing to this sink. The sink's output will be ignored.
       *
       * <p>{@link #abort()} will not be called after a call to {@link #close()}.
       */
      public void abort() throws IOException;
    }
  
    /** Returns whether this Sink can be restarted. */
    public boolean supportsRestart() {
      return false;
    }
  }
  