ShardChunkManager* ShardChunkManager::cloneMinus( const BSONObj& min, const BSONObj& max, const ShardChunkVersion& version ) {
// check that we have the exact chunk that will be subtracted
_assertChunkExists( min , max );
auto_ptr<ShardChunkManager> p( new ShardChunkManager );
p->_key = this->_key;
if ( _chunksMap.size() == 1 ) {
// if left with no chunks, just reset version
uassert( 13590 , str::stream() << "setting version to " << version.toString() << " on removing last chunk", ! version.isSet() );
p->_version = ShardChunkVersion( 0, OID() );
p->_collVersion = _collVersion;
}
else {
// can't move version backwards when subtracting chunks
// this is what guarantees that no read or write would be taken once we subtract data from the current shard
if ( version <= _version ) {
uasserted( 13585 , str::stream() << "version " << version.toString() << " not greater than " << _version.toString() );
}
p->_chunksMap = this->_chunksMap;
p->_chunksMap.erase( min );
p->_version = version;
if( version > _collVersion ) p->_collVersion = version;
else p->_collVersion = this->_collVersion;
p->_fillRanges();
}
return p.release();
}
ShardChunkManager* ShardChunkManager::cloneSplit( const BSONObj& min , const BSONObj& max , const vector<BSONObj>& splitKeys ,
const ChunkVersion& version ) {
// the version required in both resulting chunks could be simply an increment in the minor portion of the current version
// however, we are enforcing uniqueness over the attributes <ns, lastmod> of the configdb collection 'chunks'
// so in practice, a migrate somewhere may force this split to pick up a version that has the major portion higher
// than the one that this shard has been using
//
// TODO drop the uniqueness constraint and tighten the check below so that only the minor portion of version changes
if ( version <= _version ) {
uasserted( 14039 , str::stream() << "version " << version.toString() << " not greater than " << _version.toString() );
}
// check that we have the exact chunk that will be split and that the split point is valid
_assertChunkExists( min , max );
for ( vector<BSONObj>::const_iterator it = splitKeys.begin() ; it != splitKeys.end() ; ++it ) {
if ( ! contains( min , max , *it ) ) {
uasserted(14040, str::stream() << "cannot split " << min << " -> " << max
<< " on " << *it);
}
}
auto_ptr<ShardChunkManager> p( new ShardChunkManager );
p->_key = this->_key;
p->_chunksMap = this->_chunksMap;
p->_version = version; // will increment second, third, ... chunks below
BSONObj startKey = min;
for ( vector<BSONObj>::const_iterator it = splitKeys.begin() ; it != splitKeys.end() ; ++it ) {
BSONObj split = *it;
p->_chunksMap[startKey] = split.getOwned();
p->_chunksMap.insert( make_pair( split.getOwned() , max.getOwned() ) );
p->_version.incMinor();
startKey = split;
}
if( version > _collVersion ) p->_collVersion = version;
else p->_collVersion = this->_collVersion;
p->_fillRanges();
return p.release();
}
