content: /*
   * 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.asterix.optimizer.rules;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  
  import org.apache.asterix.common.annotations.IndexedNLJoinExpressionAnnotation;
  import org.apache.asterix.metadata.declared.MetadataProvider;
  import org.apache.asterix.om.base.AOrderedList;
  import org.apache.asterix.om.constants.AsterixConstantValue;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.types.AOrderedListType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.commons.lang3.mutable.Mutable;
  import org.apache.commons.lang3.mutable.MutableObject;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
  import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.BroadcastExpressionAnnotation;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IExpressionAnnotation;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
  import org.apache.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
  import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  
  public class DisjunctivePredicateToJoinRule implements IAlgebraicRewriteRule {
      // Disable this rule if this option is set to 'false'
      public static final String REWRITE_OR_AS_JOIN_OPTION = "rewrite_or_as_join";
      private static final boolean REWRITE_OR_AS_JOIN_OPTION_DEFAULT = true;
  
      private Boolean isRuleEnabled;
  
      @Override
      public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
              throws AlgebricksException {
          MetadataProvider metadataProvider = (MetadataProvider) context.getMetadataProvider();
          if (isRuleEnabled == null) {
              isRuleEnabled =
                      metadataProvider.getBooleanProperty(REWRITE_OR_AS_JOIN_OPTION, REWRITE_OR_AS_JOIN_OPTION_DEFAULT);
          }
          if (!isRuleEnabled) {
              return false;
          }
          if (metadataProvider.isBlockingOperatorDisabled()) {
              return false;
          }
          SelectOperator select;
          if ((select = asSelectOperator(opRef)) == null) {
              return false;
          }
  
          AbstractFunctionCallExpression condEx;
          if ((condEx = asFunctionCallExpression(select.getCondition(), AlgebricksBuiltinFunctions.OR)) == null) {
              return false;
          }
  
          List<Mutable<ILogicalExpression>> args = condEx.getArguments();
  
          VariableReferenceExpression varEx = null;
          IAType valType = null;
          HashSet<AsterixConstantValue> values = new HashSet<>();
          List<IExpressionAnnotation> allAnnotations = Collections.emptyList();
  
          for (Mutable<ILogicalExpression> arg : args) {
              AbstractFunctionCallExpression fctCall;
              if ((fctCall = asFunctionCallExpression(arg, AlgebricksBuiltinFunctions.EQ)) == null) {
                  return false;
              }
  
              boolean haveConst = false;
              boolean haveVar = false;
              List<Mutable<ILogicalExpression>> fctArgs = fctCall.getArguments();
              for (Mutable<ILogicalExpression> fctArg : fctArgs) {
                  final ILogicalExpression argExpr = fctArg.getValue();
                  switch (argExpr.getExpressionTag()) {
                      case CONSTANT:
                          haveConst = true;
                          AsterixConstantValue value = (AsterixConstantValue) ((ConstantExpression) argExpr).getValue();
                          if (valType == null) {
                              valType = value.getObject().getType();
                          } else if (!isCompatible(valType, value.getObject().getType())) {
                              return false;
                          }
                          values.add(value);
                          break;
                      case VARIABLE:
                          haveVar = true;
                          final VariableReferenceExpression varArg = (VariableReferenceExpression) argExpr;
                          if (varEx == null) {
                              varEx = varArg;
                          } else if (!varEx.getVariableReference().equals(varArg.getVariableReference())) {
                              return false;
                          }
                          break;
                      default:
                          return false;
                  }
              }
              if (!(haveVar && haveConst)) {
                  return false;
              }
              if (fctCall.hasAnnotations()) {
                  if (allAnnotations.isEmpty()) {
                      allAnnotations = new ArrayList<>();
                  }
                  fctCall.copyAnnotationsInto(allAnnotations);
              }
          }
  
          SourceLocation sourceLoc = select.getSourceLocation();
  
          AOrderedList list = new AOrderedList(new AOrderedListType(valType, "orderedlist"));
          for (AsterixConstantValue value : values) {
              list.add(value.getObject());
          }
  
          EmptyTupleSourceOperator ets = new EmptyTupleSourceOperator();
          context.computeAndSetTypeEnvironmentForOperator(ets);
  
          ILogicalExpression cExp = new ConstantExpression(new AsterixConstantValue(list));
          Mutable<ILogicalExpression> mutCExp = new MutableObject<>(cExp);
          UnnestingFunctionCallExpression scanExp = new UnnestingFunctionCallExpression(
                  BuiltinFunctions.getBuiltinFunctionInfo(BuiltinFunctions.SCAN_COLLECTION));
          scanExp.getArguments().add(mutCExp);
          scanExp.setSourceLocation(sourceLoc);
          LogicalVariable scanVar = context.newVar();
          UnnestOperator unn = new UnnestOperator(scanVar, new MutableObject<>(scanExp));
          unn.setSourceLocation(sourceLoc);
          unn.getInputs().add(new MutableObject<>(ets));
          context.computeAndSetTypeEnvironmentForOperator(unn);
  
          IFunctionInfo eqFctInfo = BuiltinFunctions.getBuiltinFunctionInfo(AlgebricksBuiltinFunctions.EQ);
          AbstractFunctionCallExpression eqExp = new ScalarFunctionCallExpression(eqFctInfo);
          eqExp.setSourceLocation(sourceLoc);
          VariableReferenceExpression scanVarRef = new VariableReferenceExpression(scanVar);
          scanVarRef.setSourceLocation(sourceLoc);
          eqExp.getArguments().add(new MutableObject<>(scanVarRef));
          eqExp.getArguments().add(new MutableObject<>(varEx.cloneExpression()));
          // if allAnnotations contains SkipSecondaryIndexSearchExpressionAnnotation then it'll take precedence over
          // IndexedNLJoinExpressionAnnotation and index will be skipped anyway
          eqExp.putAnnotation(IndexedNLJoinExpressionAnnotation.INSTANCE_ANY_INDEX);
          BroadcastExpressionAnnotation bcast =
                  new BroadcastExpressionAnnotation(BroadcastExpressionAnnotation.BroadcastSide.LEFT); // Broadcast the OR predicates branch.
          eqExp.putAnnotation(bcast);
          eqExp.putAnnotations(allAnnotations);
  
          InnerJoinOperator jOp = new InnerJoinOperator(new MutableObject<>(eqExp));
          jOp.setSourceLocation(sourceLoc);
          jOp.getInputs().add(new MutableObject<>(unn));
          jOp.getInputs().add(select.getInputs().get(0));
  
          opRef.setValue(jOp);
          context.computeAndSetTypeEnvironmentForOperator(jOp);
  
          return true;
      }
  
      @Override
      public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
          return false;
      }
  
      /**
       * This checks the compatibility the types of the constants to ensure that the comparison behaves as expected
       * when joining. Right now this compatibility is defined as type equality, but it could we relaxed.
       * Once type promotion works correctly in all parts of the system, this check should not be needed anymore.
       * (see https://code.google.com/p/asterixdb/issues/detail?id=716)
       *
       * @param t1
       *            one type
       * @param t2
       *            another type
       * @return true, if types are equal
       */
      private static boolean isCompatible(IAType t1, IAType t2) {
          return t1.equals(t2);
      }
  
      // some helpers
  
      private static SelectOperator asSelectOperator(ILogicalOperator op) {
          return op.getOperatorTag() == LogicalOperatorTag.SELECT ? (SelectOperator) op : null;
      }
  
      private static SelectOperator asSelectOperator(Mutable<ILogicalOperator> op) {
          return asSelectOperator(op.getValue());
      }
  
      private static AbstractFunctionCallExpression asFunctionCallExpression(ILogicalExpression ex,
              FunctionIdentifier fi) {
          AbstractFunctionCallExpression fctCall = (ex.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL
                  ? (AbstractFunctionCallExpression) ex : null);
          if (fctCall != null && (fi == null || fctCall.getFunctionIdentifier().equals(fi)))
              return fctCall;
          return null;
      }
  
      private static AbstractFunctionCallExpression asFunctionCallExpression(Mutable<ILogicalExpression> ex,
              FunctionIdentifier fi) {
          return asFunctionCallExpression(ex.getValue(), fi);
      }
  }
  