water.parser.parquet.ParquetInt96TimestampConverter.java Source code

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Here is the source code for water.parser.parquet.ParquetInt96TimestampConverter.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
 * 
 *      Copyright H20.ai Limited
 *     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 water.parser.parquet;

import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;
import org.apache.parquet.io.api.Binary;

import java.util.concurrent.TimeUnit;

/**
 * Class for decoding INT96 encoded parquet timestamp to timestamp millis in GMT.
 * <p>
 * This class is equivalent of @see org.apache.hadoop.hive.ql.io.parquet.timestamp.NanoTime,
 * which produces less intermediate objects during decoding.
 * 
 * This class is a modified version of ParquetTimestampUtils from Presto project.
 */
final class ParquetInt96TimestampConverter {
    private static final int JULIAN_EPOCH_OFFSET_DAYS = 2_440_588;
    private static final long MILLIS_IN_DAY = TimeUnit.DAYS.toMillis(1);
    private static final long NANOS_PER_MILLISECOND = TimeUnit.MILLISECONDS.toNanos(1);
    private static final byte BYTES_IN_INT96_TIMESTAMP = 12;

    private ParquetInt96TimestampConverter() {
    }

    /**
     * Returns GMT timestamp from binary encoded parquet timestamp (12 bytes - julian date + time of day nanos).
     *
     * @param timestampBinary INT96 parquet timestamp
     * @return timestamp in millis, GMT timezone
     */
    public static long getTimestampMillis(Binary timestampBinary) {
        if (timestampBinary.length() != BYTES_IN_INT96_TIMESTAMP) {
            throw new IllegalArgumentException(
                    "Parquet timestamp must be 12 bytes long, actual " + timestampBinary.length());
        }
        byte[] bytes = timestampBinary.getBytes();

        // little endian encoding - bytes are red in inverted order
        long timeOfDayNanos = Longs.fromBytes(bytes[7], bytes[6], bytes[5], bytes[4], bytes[3], bytes[2], bytes[1],
                bytes[0]);
        int julianDay = Ints.fromBytes(bytes[11], bytes[10], bytes[9], bytes[8]);

        return julianDayToMillis(julianDay) + (timeOfDayNanos / NANOS_PER_MILLISECOND);
    }

    /**
     * @param julianDay Day since the beginning of Julian calendar
     * @return millis since epoch
     */
    private static long julianDayToMillis(int julianDay) {
        return (julianDay - JULIAN_EPOCH_OFFSET_DAYS) * MILLIS_IN_DAY;
    }
}