Example usage for com.google.common.hash HashFunction hashUnencodedChars

Introduction

In this page you can find the example usage for com.google.common.hash HashFunction hashUnencodedChars.

Prototype

HashCode hashUnencodedChars(CharSequence input);

Source Link

Document

Shortcut for newHasher().putUnencodedChars(input).hash() .

Usage

From source file:io.prestosql.plugin.hive.statistics.MetastoreHiveStatisticsProvider.java

@VisibleForTesting
static List<HivePartition> getPartitionsSample(List<HivePartition> partitions, int sampleSize) {
    checkArgument(sampleSize > 0, "sampleSize is expected to be greater than zero");

    if (partitions.size() <= sampleSize) {
        return partitions;
    }// w ww  .  j  a v a2s. c o m

    List<HivePartition> result = new ArrayList<>();

    int samplesLeft = sampleSize;

    HivePartition min = partitions.get(0);
    HivePartition max = partitions.get(0);
    for (HivePartition partition : partitions) {
        if (partition.getPartitionId().compareTo(min.getPartitionId()) < 0) {
            min = partition;
        } else if (partition.getPartitionId().compareTo(max.getPartitionId()) > 0) {
            max = partition;
        }
    }

    result.add(min);
    samplesLeft--;
    if (samplesLeft > 0) {
        result.add(max);
        samplesLeft--;
    }

    if (samplesLeft > 0) {
        HashFunction hashFunction = murmur3_128();
        Comparator<Map.Entry<HivePartition, Long>> hashComparator = Comparator.<Map.Entry<HivePartition, Long>, Long>comparing(
                Map.Entry::getValue).thenComparing(entry -> entry.getKey().getPartitionId());
        partitions.stream().filter(partition -> !result.contains(partition))
                .map(partition -> immutableEntry(partition,
                        hashFunction.hashUnencodedChars(partition.getPartitionId()).asLong()))
                .sorted(hashComparator).limit(samplesLeft).forEachOrdered(entry -> result.add(entry.getKey()));
    }

    return unmodifiableList(result);
}

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