/**
* Copyright 2011 Interllective Inc.
*
* Licensed 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.
* This class exists to produce JSON strings from mongo to be consumed by streaming scripts
*
*/
package org.apache.hadoop.contrib.mongoreduce;
import java.io.IOException;
import java.net.InetAddress;
import java.util.ArrayList;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.bson.types.ObjectId;
import com.mongodb.BasicDBObject;
import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.Bytes;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.util.JSON;
@SuppressWarnings("deprecation")
public class MongoStreamRecordReader implements RecordReader<Text, Text> {
private DBCursor cursor;
private float totalResults;
private float resultsRead;
static DBObject replSetStatCmd;
{
BasicDBObjectBuilder cmdBuilder = new BasicDBObjectBuilder();
cmdBuilder.add("replSetGetStatus", 1);
replSetStatCmd = cmdBuilder.get();
}
public MongoStreamRecordReader(InputSplit split, JobConf conf) throws IOException {
// determine if any locations are local
ArrayList<String> sortedLocations = new ArrayList<String>();
ArrayList<String> localLocations = new ArrayList<String>();
ArrayList<String> remoteLocations = new ArrayList<String>();
InetAddress local = InetAddress.getLocalHost();
// see if any of these is local
for(String loc : split.getLocations()) {
String[] parts = loc.split(":");
InetAddress host = InetAddress.getByName(parts[0]);
if(local.equals(host)) {
System.err.println(loc + " is local");
localLocations.add(loc);
}
else {
remoteLocations.add(loc);
}
}
if(localLocations.size() == 0)
System.err.println("no input split locations are local");
// try local first, then remote
for(String loc : localLocations)
sortedLocations.add(loc);
for(String loc : remoteLocations)
sortedLocations.add(loc);
// read from one of the locations for this shard
for(String loc : split.getLocations()) {
try {
connect(loc, conf);
return;
}
catch (IOException e) {
// try another location
System.err.println("trying another location for input split");
}
}
String locs = "";
for(String loc : split.getLocations())
locs += loc + ", ";
throw new IOException("could not read from any replicas for shard locations: " + locs);
// this means the MapReduce will fail - unless maybe the user says not to ...
}
private void connect(String location, Configuration conf) throws IOException {
String[] parts = location.split(":");
// default port for sharded server
int port = 27018;
if(parts.length > 1)
port = Integer.parseInt(parts[1]);
Mongo mongo = new Mongo(parts[0], port);
// figure out if we can read from this server
// allow reading from secondaries
mongo.slaveOk();
String database = conf.get("mongo.input.database");
String collection = conf.get("mongo.input.collection");
String query = conf.get("mongo.input.query", "");
String select = conf.get("mongo.input.select","");
if(!query.equals("")) {
DBObject q = (DBObject) JSON.parse(query);
if(!select.equals("")) {
DBObject s = (DBObject) JSON.parse(select);
cursor = mongo.getDB(database).getCollection(collection).find(q, s);
}
else {
cursor = mongo.getDB(database).getCollection(collection).find(q);
}
}
else {
if(!select.equals("")) {
DBObject s = (DBObject) JSON.parse(select);
cursor = mongo.getDB(database).getCollection(collection).find(new BasicDBObject(), s);
}
else {
cursor = mongo.getDB(database).getCollection(collection).find();
}
}
cursor.addOption(Bytes.QUERYOPTION_NOTIMEOUT);
// thanks mongo, for this handy method
totalResults = cursor.count();
resultsRead = 0.0f;
}
//@Override
public void close() throws IOException {
cursor.close();
}
//@Override
public Text createKey() {
return new Text();
}
//@Override
public Text createValue() {
return new Text();
}
//@Override
public long getPos() throws IOException {
return (long)resultsRead;
}
//@Override
public boolean next(Text key, Text value) throws IOException {
boolean hadMore = cursor.hasNext();
if(hadMore) {
DBObject v = cursor.next();
Object objID = v.get("_id");
try {
if(objID.getClass().getName().equals(Class.forName("org.bson.types.ObjectId").getName()))
key.set(((ObjectId)v.get("_id")).toString().getBytes("UTF-8"));
else
key.set(objID.toString().getBytes("UTF-8"));
} catch (ClassNotFoundException e) {
throw new IOException(e);
}
// remove object ID from DBObject
v.removeField("_id");
value.set(v.toString().getBytes("UTF-8"));
resultsRead++;
}
return hadMore;
}
//@Override
public float getProgress() throws IOException {
return resultsRead / totalResults;
}
}