DalRequest.java

package com.ctrip.platform.dal.dao.task;

import java.sql.SQLException;
import java.util.Map;
import java.util.concurrent.Callable;

import com.ctrip.platform.dal.dao.ResultMerger;

public interface DalRequest<T> {
	/**
	 * Validate request
	 * @throws SQLException
	 */
	void validate() throws SQLException;

	/**
	 * @return true if it is cross shard
	 */
	boolean isCrossShard() throws SQLException;
	
	/**
	 * Create single task for incoming request
	 * @return
	 * @throws SQLException
	 */
	Callable<T> createTask() throws SQLException;
	
	/**
	 * To split by DB shard
	 * @return map of shard id to callable
	 */
	Map<String, Callable<T>> createTasks() throws SQLException;
	
	/**
	 * @return result merge in cross shard case
	 */
	ResultMerger<T> getMerger();
}