/**
* 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.hadoop.hive.ql.udf.generic;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde.Constants;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.StringObjectInspector;
import org.apache.hadoop.io.Text;
import org.json.JSONException;
import org.json.JSONObject;
/**
* GenericUDTFJSONTuple: this
*
*/
@Description(name = "json_tuple",
value = "_FUNC_(jsonStr, p1, p2, ..., pn) - like get_json_object, but it takes multiple names and return a tuple. " +
"All the input parameters and output column types are string.")
public class GenericUDTFJSONTuple extends GenericUDTF {
private static Log LOG = LogFactory.getLog(GenericUDTFJSONTuple.class.getName());
int numCols; // number of output columns
String[] paths; // array of path expressions, each of which corresponds to a column
Text[] retCols; // array of returned column values
Text[] cols; // object pool of non-null Text, avoid creating objects all the time
Object[] nullCols; // array of null column values
ObjectInspector[] inputOIs; // input ObjectInspectors
boolean pathParsed = false;
boolean seenErrors = false;
//An LRU cache using a linked hash map
static class HashCache<K, V> extends LinkedHashMap<K, V> {
private static final int CACHE_SIZE = 16;
private static final int INIT_SIZE = 32;
private static final float LOAD_FACTOR = 0.6f;
HashCache() {
super(INIT_SIZE, LOAD_FACTOR);
}
private static final long serialVersionUID = 1;
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > CACHE_SIZE;
}
}
static Map<String, JSONObject> jsonObjectCache = new HashCache<String, JSONObject>();
@Override
public void close() throws HiveException {
}
@Override
public StructObjectInspector initialize(ObjectInspector[] args)
throws UDFArgumentException {
inputOIs = args;
numCols = args.length - 1;
if (numCols < 1) {
throw new UDFArgumentException("json_tuple() takes at least two arguments: " +
"the json string and a path expression");
}
for (int i = 0; i < args.length; ++i) {
if (args[i].getCategory() != ObjectInspector.Category.PRIMITIVE ||
!args[i].getTypeName().equals(Constants.STRING_TYPE_NAME)) {
throw new UDFArgumentException("json_tuple()'s arguments have to be string type");
}
}
seenErrors = false;
pathParsed = false;
paths = new String[numCols];
cols = new Text[numCols];
retCols = new Text[numCols];
nullCols = new Object[numCols];
for (int i = 0; i < numCols; ++i) {
cols[i] = new Text();
retCols[i] = cols[i];
nullCols[i] = null;
}
// construct output object inspector
ArrayList<String> fieldNames = new ArrayList<String>(numCols);
ArrayList<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>(numCols);
for (int i = 0; i < numCols; ++i) {
// column name can be anything since it will be named by UDTF as clause
fieldNames.add("c" + i);
// all returned type will be Text
fieldOIs.add(PrimitiveObjectInspectorFactory.writableStringObjectInspector);
}
return ObjectInspectorFactory.getStandardStructObjectInspector(fieldNames, fieldOIs);
}
@Override
public void process(Object[] o) throws HiveException {
if (o[0] == null) {
forward(nullCols);
return;
}
// get the path expression for the 1st row only
if (!pathParsed) {
for (int i = 0;i < numCols; ++i) {
paths[i] = ((StringObjectInspector) inputOIs[i+1]).getPrimitiveJavaObject(o[i+1]);
}
pathParsed = true;
}
String jsonStr = ((StringObjectInspector) inputOIs[0]).getPrimitiveJavaObject(o[0]);
if (jsonStr == null) {
forward(nullCols);
return;
}
try {
JSONObject jsonObj = jsonObjectCache.get(jsonStr);
if (jsonObj == null) {
jsonObj = new JSONObject(jsonStr);
jsonObjectCache.put(jsonStr, jsonObj);
}
for (int i = 0; i < numCols; ++i) {
if (jsonObj.isNull(paths[i])) {
retCols[i] = null;
} else {
if (retCols[i] == null) {
retCols[i] = cols[i]; // use the object pool rather than creating a new object
}
retCols[i].set(jsonObj.getString(paths[i]));
}
}
forward(retCols);
return;
} catch (JSONException e) {
// parsing error, invalid JSON string
if (!seenErrors) {
LOG.error("The input is not a valid JSON string: " + jsonStr + ". Skipping such error messages in the future.");
seenErrors = true;
}
forward(nullCols);
return;
} catch (Throwable e) {
LOG.error("JSON parsing/evaluation exception" + e);
forward(nullCols);
}
}
@Override
public String toString() {
return "json_tuple";
}
}