/*
* 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.newplan.logical.relational;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.util.HashOutputStream;
import org.apache.pig.newplan.BaseOperatorPlan;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.logical.DotLOPrinter;
import org.apache.pig.newplan.logical.optimizer.LogicalPlanPrinter;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hashing;
/**
* LogicalPlan is the logical view of relational operations Pig will execute
* for a given script. Note that it contains only relational operations.
* All expressions will be contained in LogicalExpressionPlans inside
* each relational operator.
*/
public class LogicalPlan extends BaseOperatorPlan {
public LogicalPlan(LogicalPlan other) {
// shallow copy constructor
super(other);
}
public LogicalPlan() {
super();
}
/**
* Equality is checked by calling equals on every leaf in the plan. This
* assumes that plans are always connected graphs. It is somewhat
* inefficient since every leaf will test equality all the way to
* every root. But it is only intended for use in testing, so that
* should be ok. Checking predecessors (as opposed to successors) was
* chosen because splits (which have multiple successors) do not depend
* on order of outputs for correctness, whereas joins (with multiple
* predecessors) do. That is, reversing the outputs of split in the
* graph has no correctness implications, whereas reversing the inputs
* of join can. This method of doing equals will detect predecessors
* in different orders but not successors in different orders.
* It will return false if either plan has non deterministic EvalFunc.
*/
@Override
public boolean isEqual(OperatorPlan other) throws FrontendException {
if (other == null || !(other instanceof LogicalPlan)) {
return false;
}
return super.isEqual(other);
}
@Override
public void explain(PrintStream ps, String format, boolean verbose)
throws FrontendException {
if (format.equals("xml")) {
ps.println("<logicalPlan>XML Not Supported</logicalPlan>");
return;
}
ps.println("#-----------------------------------------------");
ps.println("# New Logical Plan:");
ps.println("#-----------------------------------------------");
if (this.size() == 0) {
ps.println("Logical plan is empty.");
} else if (format.equals("dot")) {
DotLOPrinter lpp = new DotLOPrinter(this, ps);
lpp.dump();
} else {
LogicalPlanPrinter npp = new LogicalPlanPrinter(this, ps);
npp.visit();
}
}
public Operator findByAlias(String alias) {
Iterator<Operator> it = getOperators();
List<Operator> ops = new ArrayList<Operator>();
while( it.hasNext() ) {
LogicalRelationalOperator op = (LogicalRelationalOperator) it.next();
if(op.getAlias() == null)
continue;
if(op.getAlias().equals( alias ) ) {
ops.add( op );
}
}
if( ops.isEmpty() ) {
return null;
} else {
return ops.get( ops.size() - 1 ); // Last one
}
}
/**
* Returns the signature of the LogicalPlan. The signature is a unique identifier for a given
* plan generated by a Pig script. The same script run multiple times with the same version of
* Pig is guaranteed to produce the same signature, even if the input or output locations differ.
*
* @return a unique identifier for the logical plan
* @throws FrontendException if signature can't be computed
*/
public String getSignature() throws FrontendException {
// Use a streaming hash function. goodFastHash(32) is murmur3 32 bits
HashFunction hf = Hashing.goodFastHash(32);
HashOutputStream hos = new HashOutputStream(hf);
PrintStream ps = new PrintStream(hos);
LogicalPlanPrinter printer = new LogicalPlanPrinter(this, ps);
printer.visit();
return Integer.toString(hos.getHashCode().asInt());
}
}