com.cloudera.exhibit.thrift.ThriftObsDescriptor.java Source code

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Here is the source code for com.cloudera.exhibit.thrift.ThriftObsDescriptor.java

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/*
 * Copyright (c) 2015, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.exhibit.thrift;

import com.cloudera.exhibit.core.ObsDescriptor;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import org.apache.thrift.TBase;
import org.apache.thrift.TFieldIdEnum;
import org.apache.thrift.meta_data.FieldMetaData;
import org.apache.thrift.protocol.TType;

import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class ThriftObsDescriptor implements ObsDescriptor {
    private final List<FieldData> fields;

    public ThriftObsDescriptor(Class<? extends TBase> thriftClass) {
        Map<? extends TFieldIdEnum, FieldMetaData> mdm = FieldMetaData.getStructMetaDataMap(thriftClass);
        this.fields = Lists.newArrayListWithExpectedSize(mdm.size());
        for (Map.Entry<? extends TFieldIdEnum, FieldMetaData> e : mdm.entrySet()) {
            fields.add(new FieldData(e.getKey(), e.getValue()));
        }
    }

    @Override
    public int size() {
        return fields.size();
    }

    Object getFieldValue(int i, TBase tBase) {
        return tBase.getFieldValue(fields.get(i).id);
    }

    private static final Map<Byte, FieldType> TYPE_CLASSES = ImmutableMap.<Byte, FieldType>builder()
            .put(TType.BOOL, FieldType.BOOLEAN).put(TType.DOUBLE, FieldType.DOUBLE)
            .put(TType.I16, FieldType.INTEGER).put(TType.I32, FieldType.INTEGER).put(TType.I64, FieldType.LONG)
            .put(TType.STRING, FieldType.STRING).build();

    private static FieldType getFieldType(FieldMetaData metadata) {
        byte type = metadata.valueMetaData.type;
        if (TYPE_CLASSES.containsKey(type)) {
            return TYPE_CLASSES.get(type);
        } else {
            throw new UnsupportedOperationException("Unsupported Thrift type: " + type);
        }
    }

    @Override
    public Field get(int i) {
        FieldData fd = fields.get(i);
        return new Field(fd.metadata.fieldName, getFieldType(fd.metadata));
    }

    @Override
    public int indexOf(String name) {
        return 0;
    }

    @Override
    public Iterator<Field> iterator() {
        return Iterators.transform(fields.iterator(), new Function<FieldData, Field>() {
            @Override
            public Field apply(FieldData fieldData) {
                return new Field(fieldData.metadata.fieldName, getFieldType(fieldData.metadata));
            }
        });
    }

    private static class FieldData {
        TFieldIdEnum id;
        FieldMetaData metadata;

        public FieldData(TFieldIdEnum id, FieldMetaData metadata) {
            this.id = id;
            this.metadata = metadata;
        }
    }
}