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Diffstat (limited to 'src/mongo/s/grid.h')
| -rw-r--r-- | src/mongo/s/grid.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/src/mongo/s/grid.h b/src/mongo/s/grid.h new file mode 100644 index 00000000000..ba8886317bc --- /dev/null +++ b/src/mongo/s/grid.h @@ -0,0 +1,152 @@ +// 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 <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 { + 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 ); + + /** + * removes db entry - only this DBConfig object will be removed, + * other DBConfigs which may have been created in the meantime will not be harmed + * on next getDBConfig call will fetch from db + * + * Using this method avoids race conditions where multiple threads detect a database + * reload has failed. + * + * Example : N threads receive version exceptions and dbConfig.reload(), while + * simultaneously a dropDatabase is occurring. In the meantime, the dropDatabase call + * attempts to create a DBConfig object if one does not exist, to load the db info, + * but the config is repeatedly deleted as soon as it is created. Using this method + * prevents the deletion of configs we don't know about. + * + */ + void removeDBIfExists( const DBConfig& database ); + + /** + * @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 string& ns = "", BSONObj* balancerDocOut = 0 ) const; + + /** + * + * Obtain grid configuration and settings data. + * + * @param name identifies a particular type of configuration data. + * @return a BSON object containing the requested data. + */ + BSONObj getConfigSetting( string name ) 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 ); + + 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 ); + + /** + * @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 |