/**
* 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.hadoop.hive.ql.exec;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.CommandNeedRetryException;
import org.apache.hadoop.hive.ql.Context;
import org.apache.hadoop.hive.ql.DriverContext;
import org.apache.hadoop.hive.ql.QueryPlan;
import org.apache.hadoop.hive.ql.io.HiveInputFormat;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.metadata.VirtualColumn;
import org.apache.hadoop.hive.ql.plan.FetchWork;
import org.apache.hadoop.hive.ql.plan.TableDesc;
import org.apache.hadoop.hive.ql.plan.api.StageType;
import org.apache.hadoop.hive.serde2.ColumnProjectionUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.util.StringUtils;
/**
* FetchTask implementation.
**/
public class FetchTask extends Task<FetchWork> implements Serializable {
private static final long serialVersionUID = 1L;
private int maxRows = 100;
private FetchOperator fetch;
private ListSinkOperator sink;
private int totalRows;
private static transient final Log LOG = LogFactory.getLog(FetchTask.class);
public FetchTask() {
super();
}
@Override
public void initialize(HiveConf conf, QueryPlan queryPlan, DriverContext ctx) {
super.initialize(conf, queryPlan, ctx);
work.initializeForFetch();
try {
// Create a file system handle
JobConf job = new JobConf(conf);
Operator<?> source = work.getSource();
if (source instanceof TableScanOperator) {
TableScanOperator ts = (TableScanOperator) source;
HiveInputFormat.pushFilters(job, ts);
ColumnProjectionUtils.appendReadColumnIDs(job, ts.getNeededColumnIDs());
}
sink = work.getSink();
fetch = new FetchOperator(work, job, source, getVirtualColumns(source));
source.initialize(conf, new ObjectInspector[]{fetch.getOutputObjectInspector()});
} catch (Exception e) {
// Bail out ungracefully - we should never hit
// this here - but would have hit it in SemanticAnalyzer
LOG.error(StringUtils.stringifyException(e));
throw new RuntimeException(e);
}
}
private List<VirtualColumn> getVirtualColumns(Operator<?> ts) {
if (ts instanceof TableScanOperator && ts.getConf() != null) {
return ((TableScanOperator)ts).getConf().getVirtualCols();
}
return null;
}
@Override
public int execute(DriverContext driverContext) {
assert false;
return 0;
}
/**
* Return the tableDesc of the fetchWork.
*/
public TableDesc getTblDesc() {
return work.getTblDesc();
}
/**
* Return the maximum number of rows returned by fetch.
*/
public int getMaxRows() {
return maxRows;
}
/**
* Set the maximum number of rows returned by fetch.
*/
public void setMaxRows(int maxRows) {
this.maxRows = maxRows;
}
@Override
public boolean fetch(ArrayList<String> res) throws IOException, CommandNeedRetryException {
sink.reset(res);
try {
int rowsRet = work.getLeastNumRows();
if (rowsRet <= 0) {
rowsRet = work.getLimit() >= 0 ? Math.min(work.getLimit() - totalRows, maxRows) : maxRows;
}
if (rowsRet <= 0) {
fetch.clearFetchContext();
return false;
}
boolean fetched = false;
while (sink.getNumRows() < rowsRet) {
if (!fetch.pushRow()) {
if (work.getLeastNumRows() > 0) {
throw new CommandNeedRetryException();
}
return fetched;
}
fetched = true;
}
return true;
} catch (CommandNeedRetryException e) {
throw e;
} catch (IOException e) {
throw e;
} catch (Exception e) {
throw new IOException(e);
} finally {
totalRows += sink.getNumRows();
}
}
@Override
public StageType getType() {
return StageType.FETCH;
}
@Override
public String getName() {
return "FETCH";
}
/**
* Clear the Fetch Operator.
*
* @throws HiveException
*/
public void clearFetch() throws HiveException {
if (fetch != null) {
fetch.clearFetchContext();
}
}
}