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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.drill.exec.store.parquet.columnreaders;
import org.apache.drill.common.exceptions.ExecutionSetupException;
import org.apache.drill.exec.vector.BaseValueVector;
import org.apache.drill.exec.vector.NullableVectorDefinitionSetter;
import org.apache.drill.exec.vector.ValueVector;
import parquet.column.ColumnDescriptor;
import parquet.format.SchemaElement;
import parquet.hadoop.metadata.ColumnChunkMetaData;
import java.io.IOException;
abstract class NullableColumnReader<V extends ValueVector> extends ColumnReader<V>{
int nullsFound;
// used to skip nulls found
int rightBitShift;
// used when copying less than a byte worth of data at a time, to indicate the number of used bits in the current byte
int bitsUsed;
BaseValueVector castedBaseVector;
NullableVectorDefinitionSetter castedVectorMutator;
long definitionLevelsRead;
long totalDefinitionLevelsRead;
NullableColumnReader(ParquetRecordReader parentReader, int allocateSize, ColumnDescriptor descriptor, ColumnChunkMetaData columnChunkMetaData,
boolean fixedLength, V v, SchemaElement schemaElement) throws ExecutionSetupException {
super(parentReader, allocateSize, descriptor, columnChunkMetaData, fixedLength, v, schemaElement);
castedBaseVector = (BaseValueVector) v;
castedVectorMutator = (NullableVectorDefinitionSetter) v.getMutator();
totalDefinitionLevelsRead = 0;
}
public void processPages(long recordsToReadInThisPass) throws IOException {
int indexInOutputVector = 0;
readStartInBytes = 0;
readLength = 0;
readLengthInBits = 0;
recordsReadInThisIteration = 0;
vectorData = castedBaseVector.getData();
// values need to be spaced out where nulls appear in the column
// leaving blank space for nulls allows for random access to values
// to optimize copying data out of the buffered disk stream, runs of defined values
// are located and copied together, rather than copying individual values
long runStart = pageReader.readPosInBytes;
int runLength;
int currentDefinitionLevel;
boolean lastValueWasNull;
boolean lastRunBrokenByNull = false;
while (indexInOutputVector < recordsToReadInThisPass && indexInOutputVector < valueVec.getValueCapacity()){
// read a page if needed
if ( pageReader.currentPage == null
|| ((readStartInBytes + readLength >= pageReader.byteLength && bitsUsed == 0) &&
definitionLevelsRead >= pageReader.currentPage.getValueCount())) {
if (!pageReader.next()) {
break;
}
definitionLevelsRead = 0;
}
lastValueWasNull = true;
runLength = 0;
if (lastRunBrokenByNull ) {
nullsFound = 1;
lastRunBrokenByNull = false;
} else {
nullsFound = 0;
}
// loop to find the longest run of defined values available, can be preceded by several nulls
while(indexInOutputVector < recordsToReadInThisPass
&& indexInOutputVector < valueVec.getValueCapacity()
&& definitionLevelsRead < pageReader.currentPage.getValueCount()){
currentDefinitionLevel = pageReader.definitionLevels.readInteger();
definitionLevelsRead++;
indexInOutputVector++;
totalDefinitionLevelsRead++;
if ( currentDefinitionLevel < columnDescriptor.getMaxDefinitionLevel()){
// a run of non-null values was found, break out of this loop to do a read in the outer loop
if ( ! lastValueWasNull ){
lastRunBrokenByNull = true;
break;
}
nullsFound++;
lastValueWasNull = true;
}
else{
if (lastValueWasNull){
runLength = 0;
lastValueWasNull = false;
}
runLength++;
castedVectorMutator.setIndexDefined(indexInOutputVector - 1);
}
}
valuesReadInCurrentPass += nullsFound;
int writerIndex = ((BaseValueVector) valueVec).getData().writerIndex();
if ( dataTypeLengthInBits > 8 || (dataTypeLengthInBits < 8 && totalValuesRead + runLength % 8 == 0)){
castedBaseVector.getData().setIndex(0, writerIndex + (int) Math.ceil( nullsFound * dataTypeLengthInBits / 8.0));
}
else if (dataTypeLengthInBits < 8){
rightBitShift += dataTypeLengthInBits * nullsFound;
}
this.recordsReadInThisIteration = runLength;
// set up metadata
this.readStartInBytes = pageReader.readPosInBytes;
this.readLengthInBits = recordsReadInThisIteration * dataTypeLengthInBits;
this.readLength = (int) Math.ceil(readLengthInBits / 8.0);
readField( runLength);
recordsReadInThisIteration += nullsFound;
valuesReadInCurrentPass += runLength;
totalValuesRead += recordsReadInThisIteration;
pageReader.valuesRead += recordsReadInThisIteration;
pageReader.readPosInBytes = readStartInBytes + readLength;
}
valuesReadInCurrentPass = indexInOutputVector;
valueVec.getMutator().setValueCount(
valuesReadInCurrentPass);
}
protected abstract void readField(long recordsToRead);
}
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