/*
* 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.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.POStatus;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.plans.PhyPlanVisitor;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.DataType;
import org.apache.pig.data.InternalDistinctBag;
import org.apache.pig.data.InternalSortedBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.plan.NodeIdGenerator;
import org.apache.pig.impl.plan.OperatorKey;
import org.apache.pig.impl.plan.VisitorException;
/**
* Find the distinct set of tuples in a bag.
* This is a blocking operator. All the input is put in the hashset implemented
* in DistinctDataBag which also provides the other DataBag interfaces.
*
*
*/
public class PODistinct extends PhysicalOperator implements Cloneable {
private static final long serialVersionUID = 1L;
private boolean inputsAccumulated = false;
private DataBag distinctBag = null;
transient private final Log log = LogFactory.getLog(getClass());
transient Iterator<Tuple> it;
public PODistinct(OperatorKey k, int rp, List<PhysicalOperator> inp) {
super(k, rp, inp);
}
public PODistinct(OperatorKey k, int rp) {
super(k, rp);
}
public PODistinct(OperatorKey k, List<PhysicalOperator> inp) {
super(k, inp);
}
public PODistinct(OperatorKey k) {
super(k);
}
@Override
public boolean isBlocking() {
return true;
}
@Override
public Result getNext(Tuple t) throws ExecException {
if (!inputsAccumulated) {
Result in = processInput();
// by default, we create InternalSortedBag, unless user configures
// explicitly to use old bag
String bagType = null;
if (PigMapReduce.sJobConfInternal.get() != null) {
bagType = PigMapReduce.sJobConfInternal.get().get("pig.cachedbag.distinct.type");
}
if (bagType != null && bagType.equalsIgnoreCase("default")) {
distinctBag = BagFactory.getInstance().newDistinctBag();
} else {
distinctBag = new InternalDistinctBag(3);
}
while (in.returnStatus != POStatus.STATUS_EOP) {
if (in.returnStatus == POStatus.STATUS_ERR) {
log.error("Error in reading from inputs");
return in;
//continue;
} else if (in.returnStatus == POStatus.STATUS_NULL) {
// Ignore the null, read the next tuple. It's not clear
// to me that we should ever get this, or if we should,
// how it differs from EOP. But ignoring it here seems
// to work.
in = processInput();
continue;
}
distinctBag.add((Tuple) in.result);
in = processInput();
}
inputsAccumulated = true;
}
if (it == null) {
it = distinctBag.iterator();
}
res.result = it.next();
if (res.result == null){
res.returnStatus = POStatus.STATUS_EOP;
reset();
} else {
res.returnStatus = POStatus.STATUS_OK;
}
return res;
}
@Override
public String name() {
return getAliasString() + "PODistinct" + "["
+ DataType.findTypeName(resultType) + "]" + " - "
+ mKey.toString();
}
@Override
public boolean supportsMultipleInputs() {
return false;
}
@Override
public boolean supportsMultipleOutputs() {
return false;
}
@Override
public void reset() {
inputsAccumulated = false;
distinctBag = null;
it = null;
}
@Override
public void visit(PhyPlanVisitor v) throws VisitorException {
v.visitDistinct(this);
}
/* (non-Javadoc)
* @see org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator#clone()
*/
@Override
public PODistinct clone() throws CloneNotSupportedException {
// TODO Auto-generated method stub
return new PODistinct(new OperatorKey(this.mKey.scope, NodeIdGenerator.getGenerator().getNextNodeId(this.mKey.scope)), this.requestedParallelism, this.inputs);
}
}