/*
* 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.split;
import com.facebook.presto.connector.ConnectorId;
import com.facebook.presto.metadata.Split;
import com.facebook.presto.spi.connector.ConnectorTransactionHandle;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import javax.annotation.Nullable;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static java.util.Objects.requireNonNull;
public class SampledSplitSource
implements SplitSource
{
private final SplitSource splitSource;
private final double sampleRatio;
public SampledSplitSource(SplitSource splitSource, double sampleRatio)
{
this.splitSource = requireNonNull(splitSource, "dataSource is null");
this.sampleRatio = sampleRatio;
}
@Nullable
@Override
public ConnectorId getConnectorId()
{
return splitSource.getConnectorId();
}
@Override
public ConnectorTransactionHandle getTransactionHandle()
{
return splitSource.getTransactionHandle();
}
@Override
public ListenableFuture<List<Split>> getNextBatch(int maxSize)
{
ListenableFuture<List<Split>> batch = splitSource.getNextBatch(maxSize);
return Futures.transform(batch, splits -> splits.stream()
.filter(input -> ThreadLocalRandom.current().nextDouble() < sampleRatio)
.collect(toImmutableList()));
}
@Override
public void close()
{
splitSource.close();
}
@Override
public boolean isFinished()
{
return splitSource.isFinished();
}
}