/*
* 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.PageBuilder;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.sql.gen.JoinCompiler;
import com.facebook.presto.sql.planner.plan.PlanNodeId;
import com.google.common.collect.ImmutableList;
import com.google.common.primitives.Ints;
import java.util.List;
import java.util.Optional;
import static com.facebook.presto.operator.GroupByHash.createGroupByHash;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static java.util.Objects.requireNonNull;
public class DistinctLimitOperator
implements Operator
{
public static class DistinctLimitOperatorFactory
implements OperatorFactory
{
private final int operatorId;
private final PlanNodeId planNodeId;
private final List<Integer> distinctChannels;
private final List<Type> types;
private final long limit;
private final Optional<Integer> hashChannel;
private boolean closed;
private final JoinCompiler joinCompiler;
public DistinctLimitOperatorFactory(
int operatorId,
PlanNodeId planNodeId,
List<? extends Type> types,
List<Integer> distinctChannels,
long limit,
Optional<Integer> hashChannel,
JoinCompiler joinCompiler)
{
this.operatorId = operatorId;
this.planNodeId = requireNonNull(planNodeId, "planNodeId is null");
this.types = ImmutableList.copyOf(requireNonNull(types, "types is null"));
this.distinctChannels = requireNonNull(distinctChannels, "distinctChannels is null");
checkArgument(limit >= 0, "limit must be at least zero");
this.limit = limit;
this.hashChannel = requireNonNull(hashChannel, "hashChannel is null");
this.joinCompiler = requireNonNull(joinCompiler, "joinCompiler 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, DistinctLimitOperator.class.getSimpleName());
return new DistinctLimitOperator(operatorContext, types, distinctChannels, limit, hashChannel, joinCompiler);
}
@Override
public void close()
{
closed = true;
}
@Override
public OperatorFactory duplicate()
{
return new DistinctLimitOperatorFactory(operatorId, planNodeId, types, distinctChannels, limit, hashChannel, joinCompiler);
}
}
private final OperatorContext operatorContext;
private final List<Type> types;
private final PageBuilder pageBuilder;
private Page outputPage;
private long remainingLimit;
private boolean finishing;
private final GroupByHash groupByHash;
private long nextDistinctId;
public DistinctLimitOperator(OperatorContext operatorContext, List<Type> types, List<Integer> distinctChannels, long limit, Optional<Integer> hashChannel, JoinCompiler joinCompiler)
{
this.operatorContext = requireNonNull(operatorContext, "operatorContext is null");
this.types = ImmutableList.copyOf(requireNonNull(types, "types is null"));
requireNonNull(distinctChannels, "distinctChannels is null");
checkArgument(limit >= 0, "limit must be at least zero");
requireNonNull(hashChannel, "hashChannel is null");
ImmutableList.Builder<Type> distinctTypes = ImmutableList.builder();
for (int channel : distinctChannels) {
distinctTypes.add(types.get(channel));
}
this.groupByHash = createGroupByHash(
operatorContext.getSession(),
distinctTypes.build(),
Ints.toArray(distinctChannels),
hashChannel,
Math.min((int) limit, 10_000),
joinCompiler);
this.pageBuilder = new PageBuilder(types);
remainingLimit = limit;
}
@Override
public OperatorContext getOperatorContext()
{
return operatorContext;
}
@Override
public List<Type> getTypes()
{
return types;
}
@Override
public void finish()
{
finishing = true;
pageBuilder.reset();
}
@Override
public boolean isFinished()
{
return (finishing && outputPage == null) || (remainingLimit == 0 && outputPage == null);
}
@Override
public boolean needsInput()
{
operatorContext.setMemoryReservation(groupByHash.getEstimatedSize());
return !finishing && remainingLimit > 0 && outputPage == null;
}
@Override
public void addInput(Page page)
{
checkState(needsInput());
operatorContext.setMemoryReservation(groupByHash.getEstimatedSize());
pageBuilder.reset();
GroupByIdBlock ids = groupByHash.getGroupIds(page);
for (int position = 0; position < ids.getPositionCount(); position++) {
if (ids.getGroupId(position) == nextDistinctId) {
pageBuilder.declarePosition();
for (int channel = 0; channel < types.size(); channel++) {
Type type = types.get(channel);
type.appendTo(page.getBlock(channel), position, pageBuilder.getBlockBuilder(channel));
}
remainingLimit--;
nextDistinctId++;
if (remainingLimit == 0) {
break;
}
}
}
if (!pageBuilder.isEmpty()) {
outputPage = pageBuilder.build();
}
}
@Override
public Page getOutput()
{
Page result = outputPage;
outputPage = null;
return result;
}
}