Java tutorial
/* * 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.vxquery.compiler.rewriter.rules.algebricksalternatives; import java.util.ArrayList; import java.util.List; import org.apache.commons.lang3.mutable.Mutable; import org.apache.commons.lang3.mutable.MutableObject; import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException; import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression; import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator; import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext; import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag; import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag; import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable; import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression; import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression; import edu.uci.ics.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions; import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier; import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator; import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator; import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities; import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; /** * Factors out function expressions from each comparison function or similarity function in join condition by assigning them to a variables, and replacing the function expressions with references to those variables. * Examples: * Plan with function expressions in comparison or similarity condition of join expression. Generates one assign operator per extracted function expression. * Example * Before plan: * join ( eq( funcX($$1), funcX($$2) ) ) * After plan: * join (eq($$3,$$4)) * assign [$$4] <- [funcY($$2)] * assign [$$3] <- [funcX($$1)] */ public class ExtractFunctionsFromJoinConditionRule implements IAlgebraicRewriteRule { @Override public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { return false; } @Override public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); if (op.getOperatorTag() != LogicalOperatorTag.INNERJOIN && op.getOperatorTag() != LogicalOperatorTag.LEFTOUTERJOIN) { return false; } AbstractBinaryJoinOperator joinOp = (AbstractBinaryJoinOperator) op; ILogicalExpression expr = joinOp.getCondition().getValue(); return assignFunctionExpressions(joinOp, expr, context); } private boolean assignFunctionExpressions(AbstractLogicalOperator joinOp, ILogicalExpression expr, IOptimizationContext context) throws AlgebricksException { if (expr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) { return false; } AbstractFunctionCallExpression fexp = (AbstractFunctionCallExpression) expr; FunctionIdentifier fi = fexp.getFunctionIdentifier(); boolean modified = false; if (fi.equals(AlgebricksBuiltinFunctions.AND) || fi.equals(AlgebricksBuiltinFunctions.OR)) { for (Mutable<ILogicalExpression> a : fexp.getArguments()) { if (assignFunctionExpressions(joinOp, a.getValue(), context)) { modified = true; } } return modified; } else if (AlgebricksBuiltinFunctions.isComparisonFunction(fi)) { for (Mutable<ILogicalExpression> exprRef : fexp.getArguments()) { if (exprRef.getValue().getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) { LogicalVariable newVar = context.newVar(); AssignOperator newAssign = new AssignOperator(newVar, new MutableObject<ILogicalExpression>(exprRef.getValue().cloneExpression())); newAssign.setExecutionMode(joinOp.getExecutionMode()); // Place assign below joinOp. List<LogicalVariable> used = new ArrayList<LogicalVariable>(); VariableUtilities.getUsedVariables(newAssign, used); Mutable<ILogicalOperator> leftBranchRef = joinOp.getInputs().get(0); ILogicalOperator leftBranch = leftBranchRef.getValue(); List<LogicalVariable> leftBranchVariables = new ArrayList<LogicalVariable>(); VariableUtilities.getLiveVariables(leftBranch, leftBranchVariables); if (leftBranchVariables.containsAll(used)) { // place assign on left branch newAssign.getInputs().add(new MutableObject<ILogicalOperator>(leftBranch)); leftBranchRef.setValue(newAssign); modified = true; } else { Mutable<ILogicalOperator> rightBranchRef = joinOp.getInputs().get(1); ILogicalOperator rightBranch = rightBranchRef.getValue(); List<LogicalVariable> rightBranchVariables = new ArrayList<LogicalVariable>(); VariableUtilities.getLiveVariables(rightBranch, rightBranchVariables); if (rightBranchVariables.containsAll(used)) { // place assign on right branch newAssign.getInputs().add(new MutableObject<ILogicalOperator>(rightBranch)); rightBranchRef.setValue(newAssign); modified = true; } } if (modified) { // Replace original expr with variable reference. exprRef.setValue(new VariableReferenceExpression(newVar)); context.computeAndSetTypeEnvironmentForOperator(newAssign); context.computeAndSetTypeEnvironmentForOperator(joinOp); } } } return modified; } else { return false; } } }