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Diffstat (limited to 'src/mongo/s/balancer_policy.h')
| -rw-r--r-- | src/mongo/s/balancer_policy.h | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/src/mongo/s/balancer_policy.h b/src/mongo/s/balancer_policy.h new file mode 100644 index 00000000000..d4ee5a718e8 --- /dev/null +++ b/src/mongo/s/balancer_policy.h @@ -0,0 +1,197 @@ +// @file balancer_policy.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/>. +*/ + +#ifndef S_BALANCER_POLICY_HEADER +#define S_BALANCER_POLICY_HEADER + +#include "mongo/db/jsobj.h" + +namespace mongo { + + + struct ChunkInfo { + const BSONObj min; + const BSONObj max; + + ChunkInfo( const BSONObj& a_min, const BSONObj& a_max ) + : min( a_min.getOwned() ), max( a_max.getOwned() ){} + + ChunkInfo( const BSONObj& chunk ) + : min( chunk["min"].Obj().getOwned() ), max( chunk["max"].Obj().getOwned() ) { + } + + string toString() const; + }; + + struct TagRange { + BSONObj min; + BSONObj max; + string tag; + + TagRange(){} + + TagRange( const BSONObj& a_min, const BSONObj& a_max, const string& a_tag ) + : min( a_min.getOwned() ), max( a_max.getOwned() ), tag( a_tag ){} + string toString() const; + }; + + class ShardInfo { + public: + ShardInfo(); + ShardInfo( long long maxSize, long long currSize, + bool draining, bool opsQueued, + const set<string>& tags = set<string>() ); + + void addTag( const string& tag ); + + /** @return true if we have the tag OR if the tag is "" */ + bool hasTag( const string& tag ) const; + + /** + * @return true if a shard cannot receive any new chunks bacause it reache 'shardLimits'. + * Expects the optional fields "maxSize", can in size in MB, and "usedSize", currently used size + * in MB, on 'shardLimits'. + */ + bool isSizeMaxed() const; + + /** + * @return true if 'shardLimist' contains a field "draining". Expects the optional field + * "isDraining" on 'shrdLimits'. + */ + bool isDraining() const { return _draining; } + + /** + * @return true if a shard currently has operations in any of its writeback queues + */ + bool hasOpsQueued() const { return _hasOpsQueued; } + + string toString() const; + + private: + long long _maxSize; + long long _currSize; + bool _draining; + bool _hasOpsQueued; + set<string> _tags; + }; + + struct MigrateInfo { + const string ns; + const string to; + const string from; + const ChunkInfo chunk; + + MigrateInfo( const string& a_ns , const string& a_to , const string& a_from , const BSONObj& a_chunk ) + : ns( a_ns ) , to( a_to ) , from( a_from ), chunk( a_chunk ) {} + + + }; + + typedef map< string,ShardInfo > ShardInfoMap; + typedef map< string,vector<BSONObj> > ShardToChunksMap; + + class DistributionStatus : boost::noncopyable { + public: + DistributionStatus( const ShardInfoMap& shardInfo, + const ShardToChunksMap& shardToChunksMap ); + + // only used when building + + /** + * @return if range is valid + */ + bool addTagRange( const TagRange& range ); + + // ---- these methods might be better suiting in BalancerPolicy + + /** + * @param forTag "" if you don't care, or a tag + * @return shard best suited to receive a chunk + */ + string getBestReceieverShard( const string& forTag ) const; + + /** + * @return the shard with the most chunks + * based on # of chunks with the given tag + */ + string getMostOverloadedShard( const string& forTag ) const; + + + // ---- basic accessors, counters, etc... + + /** @return total number of chunks */ + unsigned totalChunks() const; + + /** @return number of chunks in this shard */ + unsigned numberOfChunksInShard( const string& shard ) const; + + /** @return number of chunks in this shard with the given tag */ + unsigned numberOfChunksInShardWithTag( const string& shard, const string& tag ) const; + + /** @return chunks for the shard */ + const vector<BSONObj>& getChunks( const string& shard ) const; + + /** @return all tags we know about, not include "" */ + const set<string>& tags() const { return _allTags; } + + /** @return the right tag for chunk, possibly "" */ + string getTagForChunk( const BSONObj& chunk ) const; + + /** @return all shards we know about */ + const set<string>& shards() const { return _shards; } + + /** @return the ShardInfo for the shard */ + const ShardInfo& shardInfo( const string& shard ) const; + + /** writes all state to log() */ + void dump() const; + + private: + const ShardInfoMap& _shardInfo; + const ShardToChunksMap& _shardChunks; + map<BSONObj,TagRange> _tagRanges; + set<string> _allTags; + set<string> _shards; + }; + + class BalancerPolicy { + public: + + /** + * Returns a suggested chunk to move whithin a collection's shards, given information about + * space usage and number of chunks for that collection. If the policy doesn't recommend + * moving, it returns NULL. + * + * @param ns is the collections namepace. + * @param DistributionStatus holds all the info about the current state of the cluster/namespace + * @param balancedLastTime is the number of chunks effectively moved in the last round. + * @returns NULL or MigrateInfo of the best move to make towards balacing the collection. + * caller owns the MigrateInfo instance + */ + static MigrateInfo* balance( const string& ns, + const DistributionStatus& distribution, + int balancedLastTime ); + + + }; + + + +} // namespace mongo + +#endif // S_BALANCER_POLICY_HEADER |