/*
* 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.impl.logicalLayer;
import java.util.List;
import java.util.Map;
import java.util.ArrayList;
import org.apache.pig.PigException;
import org.apache.pig.impl.plan.DepthFirstWalker;
import org.apache.pig.impl.plan.ProjectionMap;
import org.apache.pig.impl.plan.VisitorException;
import org.apache.pig.impl.util.MultiMap;
import org.apache.pig.impl.util.Pair;
/**
* A class to visit all the projects and change them to attach to a new
* node. This class overrides all of the relational operators visit
* methods because it does not want to visit contained plans.
*/
public class ProjectFixerUpper extends LOVisitor {
private LogicalOperator mNewNode;
private LogicalOperator mOldNode;
private int mPredecessorIndex;
private boolean mUseOldNode;
private LogicalOperator mContainingNode;
private Map<Integer, Integer> mProjectionMapping;
public ProjectFixerUpper(
LogicalPlan plan,
LogicalOperator oldNode,
int oldNodeIndex,
LogicalOperator newNode,
boolean useOldNode,
LogicalOperator containingNode) throws VisitorException {
this(plan, oldNode, newNode, (Map<Integer, Integer>)null);
if(containingNode == null) {
int errCode = 1097;
String msg = "Containing node cannot be null.";
throw new VisitorException(msg, errCode, PigException.INPUT);
}
if(oldNodeIndex < 0) {
int errCode = 1098;
String msg = "Node index cannot be negative.";
throw new VisitorException(msg, errCode, PigException.INPUT);
}
mContainingNode = containingNode;
mPredecessorIndex = oldNodeIndex;
mUseOldNode = useOldNode;
}
public ProjectFixerUpper(
LogicalPlan plan,
LogicalOperator oldNode,
LogicalOperator newNode, Map<Integer, Integer> projectionMapping) throws VisitorException {
super(plan,
new DepthFirstWalker<LogicalOperator, LogicalPlan>(plan));
if(oldNode == null) {
int errCode = 1099;
String msg = "Node to be replaced cannot be null.";
throw new VisitorException(msg, errCode, PigException.INPUT);
}
mNewNode = newNode;
mOldNode = oldNode;
mProjectionMapping = projectionMapping;
}
protected void visit(LOCogroup cg) throws VisitorException {
}
protected void visit(LOSort s) throws VisitorException {
}
protected void visit(LOFilter f) throws VisitorException {
}
protected void visit(LOSplit s) throws VisitorException {
}
protected void visit(LOSplitOutput s) throws VisitorException {
}
protected void visit(LOForEach f) throws VisitorException {
}
protected void visit(LOProject p) throws VisitorException {
// Only switch the expression if this is a top level projection,
// that is, this project is pointing to a relational operator
// outside the plan).
List<LogicalOperator> preds = mPlan.getPredecessors(p);
if (preds == null || preds.size() == 0) {
if (p.getExpression().equals(mOldNode)) {
if (mNewNode == null) {
int errCode = 1100;
String msg = "Replacement node cannot be null.";
throw new VisitorException(msg, errCode, PigException.INPUT);
}
// Change the expression
p.setExpression(mNewNode);
if(p.isStar()) {
//its a project(*)
//no need of changing it
return;
}
if (mContainingNode != null) {
// use the projection mapping of mOldNode or mNewNode along
// with that of mContainingNode
// to figure out the mapping and replace the columns
// appropriately
int oldNodeColumn = p.getCol();
if (mUseOldNode) {
// use mOldNode's projection map and find the column number
// from the input that
ProjectionMap oldNodeMap = mOldNode.getProjectionMap();
if (oldNodeMap == null) {
// bail out if the projection map is null
int errCode = 2156;
String msg = "Error while fixing projections. Projection map of node to be replaced is null.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
if (!oldNodeMap.changes()) {
// no change required
return;
}
MultiMap<Integer, ProjectionMap.Column> oldNodeMappedFields = oldNodeMap
.getMappedFields();
if (oldNodeMappedFields == null) {
// there is no mapping available bail out
int errCode = 2157;
String msg = "Error while fixing projections. No mapping available in old predecessor to replace column.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
List<ProjectionMap.Column> columns = (List<ProjectionMap.Column>) oldNodeMappedFields.get(oldNodeColumn);
if (columns == null) {
// there is no mapping for oldNodeColumn
// it could be an added field; bail out
int errCode = 2158;
String msg = "Error during fixing projections. No mapping available in old predecessor for column to be replaced.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
boolean foundMapping = false;
for (ProjectionMap.Column column : columns) {
Pair<Integer, Integer> pair = column.getInputColumn();
if (pair.first.equals(mPredecessorIndex)) {
ArrayList<Integer> newColumns = new ArrayList<Integer>();
newColumns.add(pair.second);
p.setProjection(newColumns);
foundMapping = true;
break;
}
}
if (!foundMapping) {
// did not find a mapping - bail out
int errCode = 2159;
String msg = "Error during fixing projections. Could not locate replacement column from the old predecessor.";
throw new VisitorException(msg, errCode,
PigException.BUG);
} else {
// done with adjusting the column number of the
// project
return;
}
} else {
// here the projection mapping of new node has to be
// used to figure out
// the reverse mapping. From the newNode projection
// mapping search for
// the key whose value contains the pair (mOldNodeIndex,
// oldNodeColumn)
ProjectionMap newNodeMap = mNewNode.getProjectionMap();
if (newNodeMap == null) {
// did not find a mapping - bail out
int errCode = 2160;
String msg = "Error during fixing projections. Projection map of new predecessor is null.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
if (!newNodeMap.changes()) {
// no change required
return;
}
MultiMap<Integer, ProjectionMap.Column> newNodeMappedFields = newNodeMap
.getMappedFields();
if (newNodeMappedFields == null) {
// there is no mapping available bail out
int errCode = 2161;
String msg = "Error during fixing projections. No mapping available in new predecessor to replace column.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
boolean foundMapping = false;
for (Integer key : newNodeMappedFields.keySet()) {
List<ProjectionMap.Column> columns = (List<ProjectionMap.Column>) newNodeMappedFields
.get(key);
if (columns == null) {
// should not happen
int errCode = 2162;
String msg = "Error during fixing projections. Could not locate mapping for column: "
+ key + " in new predecessor.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
for (ProjectionMap.Column column : columns) {
Pair<Integer, Integer> pair = column.getInputColumn();
if (pair.first.equals(mPredecessorIndex)
&& pair.second.equals(oldNodeColumn)) {
ArrayList<Integer> newColumns = new ArrayList<Integer>();
newColumns.add(key);
p.setProjection(newColumns);
foundMapping = true;
break;
}
}
if (foundMapping) {
// done with adjusting the column number of the
// project
return;
}
}
if (!foundMapping) {
// did not find a mapping - bail out
int errCode = 2163;
String msg = "Error during fixing projections. Could not locate replacement column for column: "
+ oldNodeColumn
+ " in the new predecessor.";
throw new VisitorException(msg, errCode,
PigException.BUG);
}
}
}// end if for containing node != null
}// end if for projection expression equals mOldNode
// Remap the projection column if necessary
if (mProjectionMapping != null && !p.isStar()) {
List<Integer> oldProjection = p.getProjection();
List<Integer> newProjection = new ArrayList<Integer>(
oldProjection.size());
for (Integer i : oldProjection) {
Integer n = mProjectionMapping.get(i);
assert (n != null);
newProjection.add(n);
}
}
} else {
// TODO
// not sure if we need this. the walker should take care of this
p.getExpression().visit(this);
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("old node: " + mOldNode);
sb.append(" old node index: " + mPredecessorIndex);
sb.append(" new node: " + mNewNode);
sb.append(" containing node: " + mContainingNode);
sb.append(" mProjectionMapping: " + mProjectionMapping);
return sb.toString();
}
}