StatusWith<boost::optional<MigrateInfo>>
BalancerChunkSelectionPolicyImpl::selectSpecificChunkToMove(OperationContext* txn,
const ChunkType& chunk) {
const NamespaceString nss(chunk.getNS());
auto scopedCMStatus = ScopedChunkManager::getExisting(txn, nss);
if (!scopedCMStatus.isOK()) {
return scopedCMStatus.getStatus();
}
auto scopedCM = std::move(scopedCMStatus.getValue());
ChunkManager* const cm = scopedCM.cm();
auto tagForChunkStatus =
Grid::get(txn)->catalogManager(txn)->getTagForChunk(txn, nss.ns(), chunk);
if (!tagForChunkStatus.isOK()) {
return tagForChunkStatus.getStatus();
}
auto shardStatsStatus = _clusterStats->getStats(txn);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
auto collInfo = createCollectionDistributionInfo(shardStatsStatus.getValue(), cm);
ShardToChunksMap shardToChunksMap = std::move(std::get<0>(collInfo));
DistributionStatus distStatus(shardStatsStatus.getValue(), shardToChunksMap);
const ShardId newShardId(distStatus.getBestReceieverShard(tagForChunkStatus.getValue()));
if (newShardId.empty() || newShardId == chunk.getShard()) {
return boost::optional<MigrateInfo>();
}
return boost::optional<MigrateInfo>{MigrateInfo(nss.ns(), newShardId, chunk)};
}
boost::optional<MigrateInfo> BalancerPolicy::balanceSingleChunk(
const ChunkType& chunk,
const ShardStatisticsVector& shardStats,
const DistributionStatus& distribution) {
const string tag = distribution.getTagForChunk(chunk);
ShardId newShardId = _getLeastLoadedReceiverShard(shardStats, distribution, tag, {});
if (!newShardId.isValid() || newShardId == chunk.getShard()) {
return boost::optional<MigrateInfo>();
}
return MigrateInfo(distribution.nss().ns(), newShardId, chunk);
}
Chunk::Chunk(OperationContext* txn, ChunkManager* manager, const ChunkType& from)
: _manager(manager), _lastmod(from.getVersion()), _dataWritten(mkDataWritten()) {
string ns = from.getNS();
_shardId = from.getShard();
verify(_lastmod.isSet());
_min = from.getMin().getOwned();
_max = from.getMax().getOwned();
_jumbo = from.getJumbo();
uassert(10170, "Chunk needs a ns", !ns.empty());
uassert(13327, "Chunk ns must match server ns", ns == _manager->getns());
uassert(10172, "Chunk needs a min", !_min.isEmpty());
uassert(10173, "Chunk needs a max", !_max.isEmpty());
uassert(10171, "Chunk needs a server", grid.shardRegistry()->getShard(txn, _shardId));
}
virtual bool isTracked(const ChunkType& chunk) const {
return chunk.getShard() == _currShard;
}
