org.apache.parquet.thrift.ThriftSchemaConverter Maven / Gradle / Ivy
/*
* 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.parquet.thrift;
import com.twitter.elephantbird.thrift.TStructDescriptor;
import com.twitter.elephantbird.thrift.TStructDescriptor.Field;
import java.util.HashSet;
import java.util.Set;
import org.apache.thrift.TBase;
import org.apache.thrift.TEnum;
import org.apache.thrift.TUnion;
import org.apache.parquet.schema.Type;
import org.apache.parquet.schema.MessageType;
import org.apache.parquet.thrift.projection.FieldProjectionFilter;
import org.apache.parquet.thrift.struct.ThriftField;
import org.apache.parquet.thrift.struct.ThriftField.Requirement;
import org.apache.parquet.thrift.struct.ThriftType;
import org.apache.parquet.thrift.struct.ThriftType.*;
import org.apache.parquet.thrift.struct.ThriftType.StructType.StructOrUnionType;
import org.apache.parquet.thrift.struct.ThriftTypeID;
import org.apache.thrift.meta_data.FieldMetaData;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import static org.apache.parquet.schema.Type.Repetition.REPEATED;
/**
* Given a thrift class, this class converts it to parquet schema,
* a {@link FieldProjectionFilter} can be specified for projection pushdown.
*/
public class ThriftSchemaConverter {
private final FieldProjectionFilter fieldProjectionFilter;
public ThriftSchemaConverter() {
this(FieldProjectionFilter.ALL_COLUMNS);
}
public ThriftSchemaConverter(FieldProjectionFilter fieldProjectionFilter) {
this.fieldProjectionFilter = fieldProjectionFilter;
}
public MessageType convert(Class> thriftClass) {
return convert(toStructType(thriftClass));
}
/**
* struct is assumed to contain valid structOrUnionType metadata when used with this method.
* This method may throw if structOrUnionType is unknown.
*
* Use convertWithoutProjection below to convert a StructType to MessageType
*
* @param struct the thrift type descriptor
* @return the struct as a Parquet message type
*/
public MessageType convert(StructType struct) {
MessageType messageType = ThriftSchemaConvertVisitor.convert(struct, fieldProjectionFilter, true);
fieldProjectionFilter.assertNoUnmatchedPatterns();
return messageType;
}
/**
* struct is not required to have known structOrUnionType, which is useful
* for converting a StructType from an (older) file schema to a MessageType
*
* @param struct the thrift type descriptor
* @return the struct as a Parquet message type
*/
public static MessageType convertWithoutProjection(StructType struct) {
return ThriftSchemaConvertVisitor.convert(struct, FieldProjectionFilter.ALL_COLUMNS, false);
}
public static > StructOrUnionType structOrUnionType(Class klass) {
return TUnion.class.isAssignableFrom(klass) ? StructOrUnionType.UNION : StructOrUnionType.STRUCT;
}
public static ThriftType.StructType toStructType(Class> thriftClass) {
final TStructDescriptor struct = TStructDescriptor.getInstance(thriftClass);
return toStructType(struct);
}
private static StructType toStructType(TStructDescriptor struct) {
List fields = struct.getFields();
List children = new ArrayList(fields.size());
for (Field field : fields) {
Requirement req =
field.getFieldMetaData() == null ?
Requirement.OPTIONAL :
Requirement.fromType(field.getFieldMetaData().requirementType);
children.add(toThriftField(field.getName(), field, req));
}
return new StructType(children, structOrUnionType(struct.getThriftClass()));
}
/**
* Returns whether the given type is the element type of a list or is a
* synthetic group with one field that is the element type. This is
* determined by checking whether the type can be a synthetic group and by
* checking whether a potential synthetic group matches the expected
* ThriftField.
*
* This method never guesses because the expected ThriftField is known.
*
* @param repeatedType a type that may be the element type
* @param thriftElement the expected Schema for list elements
* @return {@code true} if the repeatedType is the element schema
*/
static boolean isListElementType(Type repeatedType,
ThriftField thriftElement) {
if (repeatedType.isPrimitive() ||
(repeatedType.asGroupType().getFieldCount() != 1) ||
(repeatedType.asGroupType().getType(0).isRepetition(REPEATED))) {
// The repeated type must be the element type because it is an invalid
// synthetic wrapper. Must be a group with one optional or required field
return true;
} else if (thriftElement != null && thriftElement.getType() instanceof StructType) {
Set fieldNames = new HashSet();
for (ThriftField field : ((StructType) thriftElement.getType()).getChildren()) {
fieldNames.add(field.getName());
}
// If the repeated type is a subset of the structure of the ThriftField,
// then it must be the element type.
return fieldNames.contains(repeatedType.asGroupType().getFieldName(0));
}
return false;
}
private static ThriftField toThriftField(String name, Field field, ThriftField.Requirement requirement) {
ThriftType type;
switch (ThriftTypeID.fromByte(field.getType())) {
case STOP:
case VOID:
default:
throw new UnsupportedOperationException("can't convert type of " + field);
case BOOL:
type = new BoolType();
break;
case BYTE:
type = new ByteType();
break;
case DOUBLE:
type = new DoubleType();
break;
case I16:
type = new I16Type();
break;
case I32:
type = new I32Type();
break;
case I64:
type = new I64Type();
break;
case STRING:
StringType stringType = new StringType();
FieldMetaData fieldMetaData = field.getFieldMetaData();
// There is no real binary type (see THRIFT-1920) in Thrift,
// binary data is represented by String type with an additional binary flag.
if (fieldMetaData != null && fieldMetaData.valueMetaData.isBinary()) {
stringType.setBinary(true);
}
type = stringType;
break;
case STRUCT:
type = toStructType(field.gettStructDescriptor());
break;
case MAP:
final Field mapKeyField = field.getMapKeyField();
final Field mapValueField = field.getMapValueField();
type = new ThriftType.MapType(
toThriftField(mapKeyField.getName(), mapKeyField, requirement),
toThriftField(mapValueField.getName(), mapValueField, requirement));
break;
case SET:
final Field setElemField = field.getSetElemField();
type = new ThriftType.SetType(toThriftField(setElemField.getName(), setElemField, requirement));
break;
case LIST:
final Field listElemField = field.getListElemField();
type = new ThriftType.ListType(toThriftField(listElemField.getName(), listElemField, requirement));
break;
case ENUM:
Collection enumValues = field.getEnumValues();
List values = new ArrayList();
for (TEnum tEnum : enumValues) {
values.add(new EnumValue(tEnum.getValue(), tEnum.toString()));
}
type = new EnumType(values);
break;
}
return new ThriftField(name, field.getId(), requirement, type);
}
}