/**
* Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
*
* Licensed 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 com.linkedin.pinot.common.query;
import com.linkedin.pinot.common.metrics.BrokerMetrics;
import com.linkedin.pinot.common.request.BrokerRequest;
import com.linkedin.pinot.common.response.BrokerResponse;
import com.linkedin.pinot.common.response.ServerInstance;
import com.linkedin.pinot.common.utils.DataTable;
import java.util.Map;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;
/**
* Interface for merging/reducing responses from a set of servers.
* @param <T> type of broker response.
*/
@ThreadSafe
public interface ReduceService<T extends BrokerResponse> {
/**
* Reduce data tables gathered from server instances to one brokerResponse.
* <p>Server instance information here is useful for debugging purpose.
*
* @param brokerRequest broker request.
* @param instanceResponseMap map from server instance to data table.
* @return broker response.
*/
@Nonnull
T reduceOnDataTable(@Nonnull BrokerRequest brokerRequest,
@Nonnull Map<ServerInstance, DataTable> instanceResponseMap);
/**
* Reduce data tables gathered from server instances to one brokerResponse.
* <p>Server instance information here is useful for debugging purpose.
*
* @param brokerRequest broker request.
* @param instanceResponseMap map from server instance to data table.
* @param brokerMetrics broker metrics to track execution statistics.
* @return broker response.
*/
@Nonnull
T reduceOnDataTable(@Nonnull BrokerRequest brokerRequest, @Nonnull Map<ServerInstance, DataTable> instanceResponseMap,
@Nullable BrokerMetrics brokerMetrics);
}