// 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 streamer;

public interface DataSource {

  /**
   * Get data from source.
   * 
   * @param block
   *          if false, then return immediately when no data is available,
   *          otherwise wait for data
   * @return new data or null, when no data is available
   */
  ByteBuffer pull(boolean block);

  /**
   * Hold data temporary to use at next pull or push.
   * 
   * @param buf
   *          a data
   */
  void pushBack(ByteBuffer buf);

  /**
   * Hold data temporary to use at next pull. Don't return abything untill given
   * amount of data will be read from source, because data will be pushed back
   * anyway.
   * 
   * @param buf
   *          a data
   * @param lengthOfFullPacket
   *          length of full block of data to read from source
   */
  void pushBack(ByteBuffer buf, int lengthOfFullPacket);

  /**
   * Send event to pads.
   * 
   * @param event
   *          a event
   * @param direction
   *          pad direction
   */
  void sendEvent(Event event, Direction direction);
}