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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
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* 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 <http://www.gnu.org/licenses/>.
*/
#pragma once
#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 {
public:
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.
* TODO - add the mongod's databases to the grid
*
* @param name is an optional string with the name of the shard. if ommited, grid will
* generate one and update the parameter.
* @param host is the complete address of the machine where the shard will be
* @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 string& host , 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;
private:
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 );
};
extern Grid grid;
} // namespace mongo
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