exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/Receiver.java

/*
 * 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.drill.exec.physical.base;

import java.util.List;

import org.apache.drill.exec.physical.MinorFragmentEndpoint;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;

/**
 * A receiver is one half of an exchange operator. The receiver is responsible for taking in one or more streams from
 * corresponding Senders.  Receivers are a special type of Physical Operator that are typically only expressed within the execution plan.
 */
public interface Receiver extends FragmentLeaf {

  /**
   * A receiver is expecting streams from one or more providing endpoints.
   * @return List of sender MinorFragmentEndpoints each containing sender fragment MinorFragmentId and endpoint where
   * it is running.
   */
  public abstract List<MinorFragmentEndpoint> getProvidingEndpoints();

  /**
   * Whether or not this receive supports out of order exchange. This provides a hint for the scheduling node on whether
   * the receiver can start work if only a subset of all sending endpoints are currently providing data. A random
   * receiver would supports this form of operation. A NWAY receiver would not.
   *
   * @return True if this receiver supports working on a streaming/out of order input.
   */
  @JsonIgnore
  public abstract boolean supportsOutOfOrderExchange();

  @JsonProperty("sender-major-fragment")
  public int getOppositeMajorFragmentId();

  @JsonProperty("spooling")
  public boolean isSpooling();
}