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// parallel.h
/* Copyright 2009 10gen 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.
*/
/**
tools for wokring in parallel/sharded/clustered environment
*/
#include "../stdafx.h"
#include "dbclient.h"
#include "../db/dbmessage.h"
namespace mongo {
/**
* this is a cursor that works over a set of servers
* can be used in serial/paralellel as controlled by sub classes
*/
class ClusteredCursor {
public:
ClusteredCursor( QueryMessage& q );
ClusteredCursor( const string& ns , const BSONObj& q , int options=0 , const BSONObj& fields=BSONObj() );
virtual ~ClusteredCursor();
virtual bool more() = 0;
virtual BSONObj next() = 0;
static BSONObj concatQuery( const BSONObj& query , const BSONObj& extraFilter );
virtual string type() const = 0;
protected:
auto_ptr<DBClientCursor> query( const string& server , int num = 0 , BSONObj extraFilter = BSONObj() );
static BSONObj _concatFilter( const BSONObj& filter , const BSONObj& extraFilter );
string _ns;
BSONObj _query;
int _options;
BSONObj _fields;
bool _done;
};
/**
* holder for a server address and a query to run
*/
class ServerAndQuery {
public:
ServerAndQuery( const string& server , BSONObj extra = BSONObj() , BSONObj orderObject = BSONObj() ) :
_server( server ) , _extra( extra.getOwned() ) , _orderObject( orderObject.getOwned() ){
}
bool operator<( const ServerAndQuery& other ) const{
if ( ! _orderObject.isEmpty() )
return _orderObject.woCompare( other._orderObject ) < 0;
if ( _server < other._server )
return true;
if ( other._server > _server )
return false;
return _extra.woCompare( other._extra ) < 0;
}
string toString() const {
StringBuilder ss;
ss << "server:" << _server << " _extra:" << _extra << " _orderObject:" << _orderObject;
return ss.str();
}
operator string() const {
return toString();
}
string _server;
BSONObj _extra;
BSONObj _orderObject;
};
/**
* runs a query in serial across any number of servers
* returns all results from 1 server, then the next, etc...
*/
class SerialServerClusteredCursor : public ClusteredCursor {
public:
SerialServerClusteredCursor( const set<ServerAndQuery>& servers , QueryMessage& q , int sortOrder=0);
virtual bool more();
virtual BSONObj next();
virtual string type() const { return "SerialServer"; }
private:
vector<ServerAndQuery> _servers;
unsigned _serverIndex;
auto_ptr<DBClientCursor> _current;
};
/**
* runs a query in parellel across N servers
* sots
*/
class ParallelSortClusteredCursor : public ClusteredCursor {
public:
ParallelSortClusteredCursor( const set<ServerAndQuery>& servers , QueryMessage& q , const BSONObj& sortKey );
ParallelSortClusteredCursor( const set<ServerAndQuery>& servers , const string& ns ,
const Query& q , int options=0, const BSONObj& fields=BSONObj() );
virtual ~ParallelSortClusteredCursor();
virtual bool more();
virtual BSONObj next();
virtual string type() const { return "ParallelSort"; }
private:
void _init();
void advance();
int _numServers;
set<ServerAndQuery> _servers;
BSONObj _sortKey;
auto_ptr<DBClientCursor> * _cursors;
BSONObj * _nexts;
};
/**
* tools for doing asynchronous operations
* right now uses underlying sync network ops and uses another thread
* should be changed to use non-blocking io
*/
class Future {
public:
class CommandResult {
public:
string getServer() const { return _server; }
bool isDone() const { return _done; }
bool ok() const {
assert( _done );
return _ok;
}
BSONObj result() const {
assert( _done );
return _res;
}
/**
blocks until command is done
returns ok()
*/
bool join();
private:
CommandResult( const string& server , const string& db , const BSONObj& cmd );
string _server;
string _db;
BSONObj _cmd;
boost::thread _thr;
BSONObj _res;
bool _done;
bool _ok;
friend class Future;
};
static void commandThread();
static shared_ptr<CommandResult> spawnCommand( const string& server , const string& db , const BSONObj& cmd );
private:
static shared_ptr<CommandResult> * _grab;
};
}
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