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/**
* Copyright (C) 2012 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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include "mongo/db/range_arithmetic.h"
#include "mongo/s/chunk_version.h"
#include "mongo/s/shard_key_pattern.h"
namespace mongo {
class ChunkType;
/**
* The collection metadata has metadata information about a collection, in particular the
* sharding information. It's main goal in life is to be capable of answering if a certain
* document belongs to it or not. (In some scenarios such as chunk migration, a given
* document is in a shard but cannot be accessed.)
*
* To build a collection from config data, please check the MetadataLoader. The methods
* here allow building a new incarnation of a collection's metadata based on an existing
* one (e.g, we're splitting in a given collection.).
*
* This class is immutable once constructed.
*/
class CollectionMetadata {
public:
/**
* The main way to construct CollectionMetadata is through MetadataLoader or the clone*()
* methods.
*
* The constructors should not be used directly outside of tests.
*/
CollectionMetadata(const BSONObj& keyPattern,
ChunkVersion collectionVersion,
ChunkVersion shardVersion,
RangeMap shardChunksMap);
~CollectionMetadata();
/**
* Returns a new metadata's instance based on 'this's state by removing a 'pending' chunk.
*
* The shard and collection version of the new metadata are unaffected. The caller owns the
* new metadata.
*/
std::unique_ptr<CollectionMetadata> cloneMinusPending(const ChunkType& chunk) const;
/**
* Returns a new metadata's instance based on 'this's state by adding a 'pending' chunk.
*
* The shard and collection version of the new metadata are unaffected. The caller owns the
* new metadata.
*/
std::unique_ptr<CollectionMetadata> clonePlusPending(const ChunkType& chunk) const;
/**
* Returns true if the document key 'key' is a valid instance of a shard key for this
* metadata. The 'key' must contain exactly the same fields as the shard key pattern.
*/
bool isValidKey(const BSONObj& key) const;
/**
* Returns true if the document key 'key' belongs to this chunkset. Recall that documents of
* an in-flight chunk migration may be present and should not be considered part of the
* collection / chunkset yet. Key must be the full shard key.
*/
bool keyBelongsToMe(const BSONObj& key) const;
/**
* Returns true if the document key 'key' is or has been migrated to this shard, and may
* belong to us after a subsequent config reload. Key must be the full shard key.
*/
bool keyIsPending(const BSONObj& key) const;
/**
* Given a key 'lookupKey' in the shard key range, get the next chunk which overlaps or is
* greater than this key. Returns true if a chunk exists, false otherwise.
*
* Passing a key that is not a valid shard key for this range results in undefined behavior.
*/
bool getNextChunk(const BSONObj& lookupKey, ChunkType* chunk) const;
/**
* Given a chunk identifying key "chunkMinKey", finds a different chunk if one exists.
*/
bool getDifferentChunk(const BSONObj& chunkMinKey, ChunkType* differentChunk) const;
/**
* Validates that the passed-in chunk's bounds exactly match a chunk in the metadata cache.
*/
Status checkChunkIsValid(const ChunkType& chunk);
/**
* Given a key in the shard key range, get the next range which overlaps or is greater than
* this key.
*
* This allows us to do the following to iterate over all orphan ranges:
*
* KeyRange range;
* BSONObj lookupKey = metadata->getMinKey();
* while( metadata->getNextOrphanRange( lookupKey, &orphanRange ) ) {
* // Do stuff with range
* lookupKey = orphanRange.maxKey;
* }
*
* @param lookupKey passing a key that does not belong to this metadata is undefined.
* @param orphanRange the output range. Note that the NS is not set.
*/
bool getNextOrphanRange(const BSONObj& lookupKey, KeyRange* orphanRange) const;
ChunkVersion getCollVersion() const {
return _collVersion;
}
ChunkVersion getShardVersion() const {
return _shardVersion;
}
const RangeMap& getChunks() const {
return _chunksMap;
}
const BSONObj& getKeyPattern() const {
return _shardKeyPattern.toBSON();
}
const std::vector<std::unique_ptr<FieldRef>>& getKeyPatternFields() const {
return _shardKeyPattern.getKeyPatternFields();
}
BSONObj getMinKey() const;
BSONObj getMaxKey() const;
std::size_t getNumChunks() const {
return _chunksMap.size();
}
/**
* BSON output of the basic metadata information (chunk and shard version).
*/
void toBSONBasic(BSONObjBuilder& bb) const;
/**
* BSON output of the chunks metadata into a BSONArray
*/
void toBSONChunks(BSONArrayBuilder& bb) const;
/**
* BSON output of the pending metadata into a BSONArray
*/
void toBSONPending(BSONArrayBuilder& bb) const;
/**
* String output of the collection and shard versions.
*/
std::string toStringBasic() const;
private:
// Shard key pattern for the collection
ShardKeyPattern _shardKeyPattern;
// a version for this collection that identifies the collection incarnation (ie, a
// dropped and recreated collection with the same name would have a different version)
ChunkVersion _collVersion;
// highest ChunkVersion for which this metadata's information is accurate
ChunkVersion _shardVersion;
// Map of chunks tracked by this shard
RangeMap _chunksMap;
// Map of ranges of chunks that are migrating but have not been confirmed added yet
RangeMap _pendingMap;
// A second map from a min key into a range or contiguous chunks. The map is redundant
// w.r.t. _chunkMap but we expect high chunk contiguity, especially in small
// installations.
RangeMap _rangesMap;
};
} // namespace mongo
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