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Diffstat (limited to 's/d_chunk_manager.h')
| -rw-r--r-- | s/d_chunk_manager.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/s/d_chunk_manager.h b/s/d_chunk_manager.h new file mode 100644 index 0000000..9fb95e7 --- /dev/null +++ b/s/d_chunk_manager.h @@ -0,0 +1,150 @@ +// @file d_chunk_manager.h + +/** +* Copyright (C) 2008 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 "../pch.h" + +#include "../db/jsobj.h" +#include "util.h" + +namespace mongo { + + /** + * Controls the boundaries of all the chunks for a given collection that live in this shard. + * + * ShardChunkManager instances never change after construction. There are methods provided that would generate a + * new manager if new chunks are added, subtracted, or split. + * + * TODO + * The responsibility of maintaining the version for a shard is still shared between this class and its caller. The + * manager does check corner cases (e.g. cloning out the last chunk generates a manager with version 0) but ultimately + * still cannot be responsible to set all versions. Currently, they are a function of the global state as opposed to + * the per-shard one. + */ + class ShardChunkManager : public boost::noncopyable { + public: + + /** + * Loads the ShardChunkManager with all boundaries for chunks of a given collection that live in an given + * shard. + * + * @param configServer name of the server where the configDB currently is. Can be empty to indicate + * that the configDB is running locally + * @param ns namespace for the collections whose chunks we're interested + * @param shardName name of the shard that this chunk matcher should track + * + * This constructor throws if collection is dropped/malformed and on connectivity errors + */ + ShardChunkManager( const string& configServer , const string& ns , const string& shardName ); + + /** + * Same as the regular constructor but used in unittest (no access to configDB required). + * + * @param collectionDoc simulates config.collection's entry for one colleciton + * @param chunksDocs simulates config.chunks' entries for one collection's shard + */ + ShardChunkManager( const BSONObj& collectionDoc , const BSONArray& chunksDoc ); + + ~ShardChunkManager() {} + + /** + * Generates a new manager based on 'this's state minus a given chunk. + * + * @param min max chunk boundaries for the chunk to subtract + * @param version that the resulting manager should be at. The version has to be higher than the current one. + * When cloning away the last chunk, verstion must be 0. + * @return a new ShardChunkManager, to be owned by the caller + */ + ShardChunkManager* cloneMinus( const BSONObj& min , const BSONObj& max , const ShardChunkVersion& version ); + + /** + * Generates a new manager based on 'this's state plus a given chunk. + * + * @param min max chunk boundaries for the chunk to add + * @param version that the resulting manager should be at. It can never be 0, though (see CloneMinus). + * @return a new ShardChunkManager, to be owned by the caller + */ + ShardChunkManager* clonePlus( const BSONObj& min , const BSONObj& max , const ShardChunkVersion& version ); + + /** + * Generates a new manager by splitting an existing chunk at one or more points. + * + * @param min max boundaries of chunk to be split + * @param splitKeys points to split original chunk at + * @param version to be used in first chunk. The subsequent chunks would increment the minor version. + * @return a new ShardChunkManager with the chunk split, to be owned by the caller + */ + ShardChunkManager* cloneSplit( const BSONObj& min , const BSONObj& max , const vector<BSONObj>& splitKeys , + const ShardChunkVersion& version ); + + /** + * Checks whether a document belongs to this shard. + * + * @param obj document containing sharding keys (and, optionally, other attributes) + * @return true if shards hold the object + */ + bool belongsToMe( const BSONObj& obj ) const; + + /** + * Given a chunk's min key (or empty doc), gets the boundary of the chunk following that one (the first). + * + * @param lookupKey is the min key for a previously obtained chunk or the empty document + * @param foundMin IN/OUT min for chunk following the one starting at lookupKey + * @param foundMax IN/OUT max for the above chunk + * @return true if the chunk returned is the last one + */ + bool getNextChunk( const BSONObj& lookupKey, BSONObj* foundMin , BSONObj* foundMax ) const; + + // accessors + + ShardChunkVersion getVersion() const { return _version; } + BSONObj getKey() const { return _key.getOwned(); } + unsigned getNumChunks() const { return _chunksMap.size(); } + + string toString() const; + private: + // highest ShardChunkVersion for which this ShardChunkManager's information is accurate + ShardChunkVersion _version; + + // key pattern for chunks under this range + BSONObj _key; + + // a map from a min key into the chunk's (or range's) max boundary + typedef map< BSONObj, BSONObj , BSONObjCmp > RangeMap; + RangeMap _chunksMap; + + // a map from a min key into a range or continguous chunks + // redundant but we expect high chunk continguity, expecially in small installations + RangeMap _rangesMap; + + /** constructors helpers */ + void _fillCollectionKey( const BSONObj& collectionDoc ); + void _fillChunks( DBClientCursorInterface* cursor ); + void _fillRanges(); + + /** throws if the exact chunk is not in the chunks' map */ + void _assertChunkExists( const BSONObj& min , const BSONObj& max ) const; + + /** can only be used in the cloning calls */ + ShardChunkManager() {} + }; + + typedef shared_ptr<ShardChunkManager> ShardChunkManagerPtr; + +} // namespace mongo |