io.prestosql.split.SampledSplitSource.java Source code

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Here is the source code for io.prestosql.split.SampledSplitSource.java

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/*
 * 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 io.prestosql.split;

import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import io.prestosql.connector.ConnectorId;
import io.prestosql.execution.Lifespan;
import io.prestosql.spi.connector.ConnectorPartitionHandle;
import io.prestosql.spi.connector.ConnectorTransactionHandle;

import javax.annotation.Nullable;

import java.util.concurrent.ThreadLocalRandom;

import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
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<SplitBatch> getNextBatch(ConnectorPartitionHandle partitionHandle, Lifespan lifespan,
            int maxSize) {
        ListenableFuture<SplitBatch> batch = splitSource.getNextBatch(partitionHandle, lifespan, maxSize);
        return Futures.transform(batch,
                splitBatch -> new SplitBatch(splitBatch.getSplits().stream()
                        .filter(input -> ThreadLocalRandom.current().nextDouble() < sampleRatio)
                        .collect(toImmutableList()), splitBatch.isLastBatch()),
                directExecutor());
    }

    @Override
    public void close() {
        splitSource.close();
    }

    @Override
    public boolean isFinished() {
        return splitSource.isFinished();
    }
}