org.apache.hadoop.hive.ql.parse.GenTezWorkWalker Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.parse;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.UnionOperator;
import org.apache.hadoop.hive.ql.lib.DefaultGraphWalker;
import org.apache.hadoop.hive.ql.lib.Dispatcher;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.plan.BaseWork;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
/**
* Walks the operator tree in DFS fashion.
*/
public class GenTezWorkWalker extends DefaultGraphWalker {
private final GenTezProcContext ctx;
/**
* constructor of the walker - the dispatcher is passed.
*
* @param disp the dispatcher to be called for each node visited
* @param ctx the context where we'll set the current root operator
*
*/
public GenTezWorkWalker(Dispatcher disp, GenTezProcContext ctx) {
super(disp);
this.ctx = ctx;
}
private void setRoot(Node nd) {
ctx.currentRootOperator = (Operator) nd;
ctx.preceedingWork = null;
ctx.parentOfRoot = null;
ctx.currentUnionOperators = new ArrayList<>();
}
/**
* starting point for walking.
*
* @throws SemanticException
*/
@Override
public void startWalking(Collection startNodes,
HashMap nodeOutput) throws SemanticException {
toWalk.addAll(startNodes);
while (toWalk.size() > 0) {
Node nd = toWalk.remove(0);
setRoot(nd);
walk(nd);
if (nodeOutput != null) {
nodeOutput.put(nd, retMap.get(nd));
}
}
}
/**
* Walk the given operator.
*
* @param nd operator being walked
*/
@Override
protected void walk(Node nd) throws SemanticException {
List children = nd.getChildren();
// maintain the stack of operators encountered
opStack.push(nd);
Boolean skip = dispatchAndReturn(nd, opStack);
// save some positional state
Operator currentRoot = ctx.currentRootOperator;
Operator parentOfRoot = ctx.parentOfRoot;
List currentUnionOperators = ctx.currentUnionOperators;
BaseWork preceedingWork = ctx.preceedingWork;
if (skip == null || !skip) {
// move all the children to the front of queue
for (Node ch : children) {
// and restore the state before walking each child
ctx.currentRootOperator = currentRoot;
ctx.parentOfRoot = parentOfRoot;
ctx.preceedingWork = preceedingWork;
ctx.currentUnionOperators = new ArrayList<>();
ctx.currentUnionOperators.addAll(currentUnionOperators);
walk(ch);
}
}
// done with this operator
opStack.pop();
}
}