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// grid.h
* Copyright (C) 2010 10gen Inc.
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU Affero General Public License for more details.
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <>.
#pragma once
#include <boost/date_time/posix_time/posix_time.hpp>
#include "../util/time_support.h"
#include "../util/concurrency/mutex.h"
#include "config.h" // DBConfigPtr
namespace mongo {
* stores meta-information about the grid
* TODO: used shard_ptr for DBConfig pointers
class Grid {
Grid() : _lock( "Grid" ) , _allowLocalShard( true ) { }
* gets the config the db.
* will return an empty DBConfig if not in db already
DBConfigPtr getDBConfig( string ns , bool create=true , const string& shardNameHint="" );
* removes db entry.
* on next getDBConfig call will fetch from db
void removeDB( string db );
* @return true if shards and config servers are allowed to use 'localhost' in address
bool allowLocalHost() const;
* @param whether to allow shards and config servers to use 'localhost' in address
void setAllowLocalHost( bool allow );
* addShard will create a new shard in the grid. It expects a mongod process to be runing
* on the provided address. Adding a shard that is a replica set is supported.
* @param name is an optional string with the name of the shard. if ommited, grid will
* generate one and update the parameter.
* @param servers is the connection string of the shard being added
* @param maxSize is the optional space quota in bytes. Zeros means there's no limitation to
* space usage
* @param errMsg is the error description in case the operation failed.
* @return true if shard was successfully added.
bool addShard( string* name , const ConnectionString& servers , long long maxSize , string& errMsg );
* @return true if the config database knows about a host 'name'
bool knowAboutShard( const string& name ) const;
* @return true if the chunk balancing functionality is enabled
bool shouldBalance() const;
unsigned long long getNextOpTime() const;
void flushConfig();
// exposed methods below are for testing only
* @param balancerDoc bson that may contain a window of time for the balancer to work
* format { ... , activeWindow: { start: "8:30" , stop: "19:00" } , ... }
* @return true if there is no window of time specified for the balancer or it we're currently in it
static bool _inBalancingWindow( const BSONObj& balancerDoc , const boost::posix_time::ptime& now );
mongo::mutex _lock; // protects _databases; TODO: change to r/w lock ??
map<string, DBConfigPtr > _databases; // maps ns to DBConfig's
bool _allowLocalShard; // can 'localhost' be used in shard addresses?
* @param name is the chose name for the shard. Parameter is mandatory.
* @return true if it managed to generate a shard name. May return false if (currently)
* 10000 shard
bool _getNewShardName( string* name ) const;
* @return whether a give dbname is used for shard "local" databases (e.g., admin or local)
static bool _isSpecialLocalDB( const string& dbName );
* @param balancerDoc bson that may contain a marker to stop the balancer
* format { ... , stopped: [ "true" | "false" ] , ... }
* @return true if the marker is present and is set to true
static bool _balancerStopped( const BSONObj& balancerDoc );
extern Grid grid;
} // namespace mongo