/*
* Licensed 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 com.facebook.presto.operator;
import com.facebook.presto.spi.Page;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.block.FixedWidthBlock;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.sql.planner.plan.PlanNodeId;
import com.google.common.collect.ImmutableList;
import io.airlift.slice.Slices;
import java.util.List;
import static com.facebook.presto.spi.StandardErrorCode.SUBQUERY_MULTIPLE_ROWS;
import static com.google.common.base.Preconditions.checkState;
import static io.airlift.slice.Slices.EMPTY_SLICE;
import static java.util.Objects.requireNonNull;
public class EnforceSingleRowOperator
implements Operator
{
public static class EnforceSingleRowOperatorFactory
implements OperatorFactory
{
private final int operatorId;
private final PlanNodeId planNodeId;
private final List<Type> types;
private boolean closed;
public EnforceSingleRowOperatorFactory(int operatorId, PlanNodeId planNodeId, List<Type> types)
{
this.operatorId = operatorId;
this.planNodeId = requireNonNull(planNodeId, "planNodeId is null");
this.types = ImmutableList.copyOf(requireNonNull(types, "type is null"));
}
@Override
public List<Type> getTypes()
{
return types;
}
@Override
public Operator createOperator(DriverContext driverContext)
{
checkState(!closed, "Factory is already closed");
OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, planNodeId, EnforceSingleRowOperator.class.getSimpleName());
return new EnforceSingleRowOperator(operatorContext, types);
}
@Override
public void close()
{
closed = true;
}
@Override
public OperatorFactory duplicate()
{
return new EnforceSingleRowOperatorFactory(operatorId, planNodeId, types);
}
}
private static final Page SINGLE_NULL_VALUE_PAGE = new Page(1, new FixedWidthBlock(0, 1, EMPTY_SLICE, Slices.wrappedBooleanArray(true)));
private final OperatorContext operatorContext;
private final List<Type> types;
private boolean finishing;
private Page page;
public EnforceSingleRowOperator(OperatorContext operatorContext, List<Type> types)
{
this.operatorContext = requireNonNull(operatorContext, "operatorContext is null");
this.types = ImmutableList.copyOf(requireNonNull(types, "types is null"));
}
@Override
public OperatorContext getOperatorContext()
{
return operatorContext;
}
@Override
public List<Type> getTypes()
{
return types;
}
@Override
public void finish()
{
if (!finishing && page == null) {
this.page = SINGLE_NULL_VALUE_PAGE;
}
finishing = true;
}
@Override
public boolean isFinished()
{
return finishing && page == null;
}
@Override
public boolean needsInput()
{
return !finishing;
}
@Override
public void addInput(Page page)
{
requireNonNull(page, "page is null");
checkState(needsInput(), "Operator did not expect any more data");
if (page.getPositionCount() == 0) {
return;
}
if (this.page != null || page.getPositionCount() > 1) {
throw new PrestoException(SUBQUERY_MULTIPLE_ROWS, "Scalar sub-query has returned multiple rows");
}
this.page = page;
}
@Override
public Page getOutput()
{
if (!finishing) {
return null;
}
checkState(page != null, "Operator is already done");
Page pageToReturn = page;
page = null;
return pageToReturn;
}
}