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MongoDbClient.java
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Thu, May 9, 16:13

MongoDbClient.java
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/**
* MongoDB client binding for YCSB.
*
* Submitted by Yen Pai on 5/11/2010.
*
* https://gist.github.com/000a66b8db2caf42467b#file_mongo_db.java
*
*/
package com.yahoo.ycsb.db;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Properties;
import java.util.Set;
import java.util.Map;
import java.util.Vector;
import com.mongodb.BasicDBObject;
import com.mongodb.DBAddress;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.WriteConcern;
import com.mongodb.WriteResult;
import com.yahoo.ycsb.DB;
import com.yahoo.ycsb.DBException;
import com.yahoo.ycsb.ByteIterator;
import com.yahoo.ycsb.StringByteIterator;
/**
* MongoDB client for YCSB framework.
*
* Properties to set:
*
* mongodb.url=mongodb://localhost:27017
* mongodb.database=ycsb
* mongodb.writeConcern=normal
*
* @author ypai
*
*/
public class MongoDbClient extends DB {
private Mongo mongo;
private WriteConcern writeConcern;
private String database;
/**
* Initialize any state for this DB. Called once per DB instance; there is
* one DB instance per client thread.
*/
public void init() throws DBException {
// initialize MongoDb driver
Properties props = getProperties();
String url = props.getProperty("mongodb.url", "mongodb://localhost:27017");
database = props.getProperty("mongodb.database", "ycsb");
String writeConcernType = props.getProperty("mongodb.writeConcern", "safe").toLowerCase();
if ("none".equals(writeConcernType)) {
writeConcern = WriteConcern.NONE;
} else if ("safe".equals(writeConcernType)) {
writeConcern = WriteConcern.SAFE;
} else if ("normal".equals(writeConcernType)) {
writeConcern = WriteConcern.NORMAL;
} else if ("fsync_safe".equals(writeConcernType)) {
writeConcern = WriteConcern.FSYNC_SAFE;
} else if ("replicas_safe".equals(writeConcernType)) {
writeConcern = WriteConcern.REPLICAS_SAFE;
} else {
System.err.println("ERROR: Invalid writeConcern: '" + writeConcernType + "'. " +
"Must be [ none | safe | normal | fsync_safe | replicas_safe ]");
System.exit(1);
}
try {
// strip out prefix since Java driver doesn't currently support
// standard connection format URL yet
// http://www.mongodb.org/display/DOCS/Connections
if (url.startsWith("mongodb://")) {
url = url.substring(10);
}
// need to append db to url.
url += "/"+database;
System.out.println("new database url = "+url);
mongo = new Mongo(new DBAddress(url));
System.out.println("mongo connection created with "+url);
} catch (Exception e1) {
System.err.println(
"Could not initialize MongoDB connection pool for Loader: "
+ e1.toString());
e1.printStackTrace();
return;
}
}
@Override
/**
* Delete a record from the database.
*
* @param table The name of the table
* @param key The record key of the record to delete.
* @return Zero on success, a non-zero error code on error. See this class's description for a discussion of error codes.
*/
public int delete(String table, String key) {
com.mongodb.DB db=null;
try {
db = mongo.getDB(database);
db.requestStart();
DBCollection collection = db.getCollection(table);
DBObject q = new BasicDBObject().append("_id", key);
WriteResult res = collection.remove(q, writeConcern);
return res.getN() == 1 ? 0 : 1;
} catch (Exception e) {
System.err.println(e.toString());
return 1;
}
finally
{
if (db!=null)
{
db.requestDone();
}
}
}
@Override
/**
* Insert a record in the database. Any field/value pairs in the specified values HashMap will be written into the record with the specified
* record key.
*
* @param table The name of the table
* @param key The record key of the record to insert.
* @param values A HashMap of field/value pairs to insert in the record
* @return Zero on success, a non-zero error code on error. See this class's description for a discussion of error codes.
*/
public int insert(String table, String key, HashMap<String, ByteIterator> values) {
com.mongodb.DB db = null;
try {
db = mongo.getDB(database);
db.requestStart();
DBCollection collection = db.getCollection(table);
DBObject r = new BasicDBObject().append("_id", key);
for(String k: values.keySet()) {
r.put(k, values.get(k).toArray());
}
WriteResult res = collection.insert(r,writeConcern);
return res.getError() == null ? 0 : 1;
} catch (Exception e) {
e.printStackTrace();
return 1;
} finally {
if (db!=null)
{
db.requestDone();
}
}
}
@Override
@SuppressWarnings("unchecked")
/**
* Read a record from the database. Each field/value pair from the result will be stored in a HashMap.
*
* @param table The name of the table
* @param key The record key of the record to read.
* @param fields The list of fields to read, or null for all of them
* @param result A HashMap of field/value pairs for the result
* @return Zero on success, a non-zero error code on error or "not found".
*/
public int read(String table, String key, Set<String> fields,
HashMap<String, ByteIterator> result) {
com.mongodb.DB db = null;
try {
db = mongo.getDB(database);
db.requestStart();
DBCollection collection = db.getCollection(table);
DBObject q = new BasicDBObject().append("_id", key);
DBObject fieldsToReturn = new BasicDBObject();
boolean returnAllFields = fields == null;
DBObject queryResult = null;
if (!returnAllFields) {
Iterator<String> iter = fields.iterator();
while (iter.hasNext()) {
fieldsToReturn.put(iter.next(), 1);
}
queryResult = collection.findOne(q, fieldsToReturn);
} else {
queryResult = collection.findOne(q);
}
if (queryResult != null) {
result.putAll(queryResult.toMap());
}
return queryResult != null ? 0 : 1;
} catch (Exception e) {
System.err.println(e.toString());
return 1;
} finally {
if (db!=null)
{
db.requestDone();
}
}
}
@Override
/**
* Update a record in the database. Any field/value pairs in the specified values HashMap will be written into the record with the specified
* record key, overwriting any existing values with the same field name.
*
* @param table The name of the table
* @param key The record key of the record to write.
* @param values A HashMap of field/value pairs to update in the record
* @return Zero on success, a non-zero error code on error. See this class's description for a discussion of error codes.
*/
public int update(String table, String key, HashMap<String, ByteIterator> values) {
com.mongodb.DB db = null;
try {
db = mongo.getDB(database);
db.requestStart();
DBCollection collection = db.getCollection(table);
DBObject q = new BasicDBObject().append("_id", key);
DBObject u = new BasicDBObject();
DBObject fieldsToSet = new BasicDBObject();
Iterator<String> keys = values.keySet().iterator();
while (keys.hasNext()) {
String tmpKey = keys.next();
fieldsToSet.put(tmpKey, values.get(tmpKey).toArray());
}
u.put("$set", fieldsToSet);
WriteResult res = collection.update(q, u, false, false,
writeConcern);
return res.getN() == 1 ? 0 : 1;
} catch (Exception e) {
System.err.println(e.toString());
return 1;
} finally {
if (db!=null)
{
db.requestDone();
}
}
}
@Override
@SuppressWarnings("unchecked")
/**
* Perform a range scan for a set of records in the database. Each field/value pair from the result will be stored in a HashMap.
*
* @param table The name of the table
* @param startkey The record key of the first record to read.
* @param recordcount The number of records to read
* @param fields The list of fields to read, or null for all of them
* @param result A Vector of HashMaps, where each HashMap is a set field/value pairs for one record
* @return Zero on success, a non-zero error code on error. See this class's description for a discussion of error codes.
*/
public int scan(String table, String startkey, int recordcount,
Set<String> fields, Vector<HashMap<String, ByteIterator>> result) {
com.mongodb.DB db=null;
try {
db = mongo.getDB(database);
db.requestStart();
DBCollection collection = db.getCollection(table);
// { "_id":{"$gte":startKey, "$lte":{"appId":key+"\uFFFF"}} }
DBObject scanRange = new BasicDBObject().append("$gte", startkey);
DBObject q = new BasicDBObject().append("_id", scanRange);
DBCursor cursor = collection.find(q).limit(recordcount);
while (cursor.hasNext()) {
//toMap() returns a Map, but result.add() expects a Map<String,String>. Hence, the suppress warnings.
result.add(StringByteIterator.getByteIteratorMap((Map<String,String>)cursor.next().toMap()));
}
return 0;
} catch (Exception e) {
System.err.println(e.toString());
return 1;
}
finally
{
if (db!=null)
{
db.requestDone();
}
}
}
}

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