andresgomezfrr commented on a change in pull request #5789: Add stringLast and stringFirst aggregators extension URL: https://github.com/apache/incubator-druid/pull/5789#discussion_r205683872
########## File path: processing/src/main/java/io/druid/query/aggregation/SerializablePairLongStringSerde.java ########## @@ -0,0 +1,180 @@ +/* + * Licensed to Metamarkets Group Inc. (Metamarkets) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. Metamarkets licenses this file + * to you 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.druid.query.aggregation; + +import io.druid.data.input.InputRow; +import io.druid.java.util.common.StringUtils; +import io.druid.segment.GenericColumnSerializer; +import io.druid.segment.column.ColumnBuilder; +import io.druid.segment.data.GenericIndexed; +import io.druid.segment.data.ObjectStrategy; +import io.druid.segment.serde.ComplexColumnPartSupplier; +import io.druid.segment.serde.ComplexMetricExtractor; +import io.druid.segment.serde.ComplexMetricSerde; +import io.druid.segment.serde.LargeColumnSupportedComplexColumnSerializer; +import io.druid.segment.writeout.SegmentWriteOutMedium; + +import java.nio.ByteBuffer; + +/** + * The SerializablePairLongStringSerde serializes a Long-String pair (SerializablePairLongString). + * The serialization structure is: Long:Integer:String + * <p> + * The class is used on first/last String aggregators to store the time and the first/last string. + * Long:Integer:String -> Timestamp:StringSize:StringData + */ +public class SerializablePairLongStringSerde extends ComplexMetricSerde +{ + + private static final String TYPE_NAME = "serializablePairLongString"; + + @Override + public String getTypeName() + { + return TYPE_NAME; + } + + @Override + public ComplexMetricExtractor getExtractor() + { + return new ComplexMetricExtractor() + { + @Override + public Class<SerializablePairLongString> extractedClass() + { + return SerializablePairLongString.class; + } + + @Override + public Object extractValue(InputRow inputRow, String metricName) + { + return inputRow.getRaw(metricName); + } + }; + } + + @Override + public void deserializeColumn(ByteBuffer buffer, ColumnBuilder columnBuilder) + { + final GenericIndexed column = GenericIndexed.read(buffer, getObjectStrategy(), columnBuilder.getFileMapper()); + columnBuilder.setComplexColumn(new ComplexColumnPartSupplier(getTypeName(), column)); + } + + @Override + public ObjectStrategy getObjectStrategy() + { + return new ObjectStrategy<SerializablePairLongString>() + { + @Override + public int compare(SerializablePairLongString o1, SerializablePairLongString o2) + { + int comparation; + + // First we check if the objects are null + if (o1 == null && o2 == null) { + comparation = 0; + } else if (o1 == null) { + comparation = -1; + } else if (o2 == null) { + comparation = 1; + } else { + + // If the objects are not null, we will try to compare using timestamp + comparation = o1.lhs.compareTo(o2.lhs); + + // If both timestamp are the same, we try to compare the Strings + if (comparation == 0) { + + // First we check if the strings are null + if (o1.rhs == null && o2.rhs == null) { + comparation = 0; + } else if (o1.rhs == null) { + comparation = -1; + } else if (o2.rhs == null) { + comparation = 1; + } else { + + // If the strings are not null, we will compare them + // Note: This comparison maybe doesn't make sense to first/last aggregators, + // because compare both SerializablePairLongString based on String maybe doesn't matter + // to define each is first or last. + comparation = o1.rhs.compareTo(o2.rhs); + } + } + } + + return comparation; + } + + @Override + public Class<? extends SerializablePairLongString> getClazz() + { + return SerializablePairLongString.class; + } + + @Override + public SerializablePairLongString fromByteBuffer(ByteBuffer buffer, int numBytes) + { + final ByteBuffer readOnlyBuffer = buffer.asReadOnlyBuffer(); + + long lhs = readOnlyBuffer.getLong(); + int stringSize = readOnlyBuffer.getInt(); + + String lastString = null; + if (stringSize > 0) { + byte[] stringBytes = new byte[stringSize]; + readOnlyBuffer.get(stringBytes, 0, stringSize); + lastString = StringUtils.fromUtf8(stringBytes); + } + + return new SerializablePairLongString(lhs, lastString); + } + + @Override + public byte[] toBytes(SerializablePairLongString val) + { + String rhsString = val.rhs; + ByteBuffer bbuf; + + Review comment: :+1: ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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