Status Balancer::moveSingleChunk(OperationContext* txn,
const ChunkType& chunk,
const ShardId& newShardId,
uint64_t maxChunkSizeBytes,
const MigrationSecondaryThrottleOptions& secondaryThrottle,
bool waitForDelete) {
auto moveAllowedStatus = _chunkSelectionPolicy->checkMoveAllowed(txn, chunk, newShardId);
if (!moveAllowedStatus.isOK()) {
return moveAllowedStatus;
}
MigrationManager migrationManager;
auto migrationStatuses = migrationManager.scheduleMigrations(
txn,
{MigrationManager::MigrationRequest(MigrateInfo(chunk.getNS(), newShardId, chunk),
maxChunkSizeBytes,
secondaryThrottle,
waitForDelete)});
invariant(migrationStatuses.size() == 1);
auto scopedCMStatus = ScopedChunkManager::getExisting(txn, NamespaceString(chunk.getNS()));
if (!scopedCMStatus.isOK()) {
return scopedCMStatus.getStatus();
}
auto scopedCM = std::move(scopedCMStatus.getValue());
ChunkManager* const cm = scopedCM.cm();
cm->reload(txn);
return migrationStatuses.begin()->second;
}
StatusWith<boost::optional<MigrateInfo>>
BalancerChunkSelectionPolicyImpl::selectSpecificChunkToMove(OperationContext* opCtx,
const ChunkType& chunk) {
auto shardStatsStatus = _clusterStats->getStats(opCtx);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
const auto& shardStats = shardStatsStatus.getValue();
auto routingInfoStatus =
Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfoWithRefresh(opCtx,
chunk.getNS());
if (!routingInfoStatus.isOK()) {
return routingInfoStatus.getStatus();
}
const auto cm = routingInfoStatus.getValue().cm().get();
const auto collInfoStatus = createCollectionDistributionStatus(opCtx, shardStats, cm);
if (!collInfoStatus.isOK()) {
return collInfoStatus.getStatus();
}
const DistributionStatus& distribution = collInfoStatus.getValue();
return BalancerPolicy::balanceSingleChunk(chunk, shardStats, distribution);
}
StatusWith<boost::optional<MigrateInfo>>
BalancerChunkSelectionPolicyImpl::selectSpecificChunkToMove(OperationContext* txn,
const ChunkType& chunk) {
auto shardStatsStatus = _clusterStats->getStats(txn);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
const auto shardStats = std::move(shardStatsStatus.getValue());
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 collInfoStatus = createCollectionDistributionInfo(txn, shardStats, cm);
if (!collInfoStatus.isOK()) {
return collInfoStatus.getStatus();
}
auto collInfo = std::move(collInfoStatus.getValue());
return BalancerPolicy::balanceSingleChunk(chunk, shardStats, std::get<0>(collInfo));
}
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)};
}
Status Balancer::moveSingleChunk(OperationContext* txn,
const ChunkType& chunk,
const ShardId& newShardId,
uint64_t maxChunkSizeBytes,
const MigrationSecondaryThrottleOptions& secondaryThrottle,
bool waitForDelete) {
auto moveAllowedStatus = _chunkSelectionPolicy->checkMoveAllowed(txn, chunk, newShardId);
if (!moveAllowedStatus.isOK()) {
return moveAllowedStatus;
}
return executeSingleMigration(txn,
MigrateInfo(chunk.getNS(), newShardId, chunk),
maxChunkSizeBytes,
secondaryThrottle,
waitForDelete);
}
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));
}
Status BalancerChunkSelectionPolicyImpl::checkMoveAllowed(OperationContext* txn,
const ChunkType& chunk,
const ShardId& newShardId) {
auto shardStatsStatus = _clusterStats->getStats(txn);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
auto shardStats = std::move(shardStatsStatus.getValue());
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 collInfoStatus = createCollectionDistributionInfo(txn, shardStats, cm);
if (!collInfoStatus.isOK()) {
return collInfoStatus.getStatus();
}
auto collInfo = std::move(collInfoStatus.getValue());
DistributionStatus distribution = std::move(std::get<0>(collInfo));
auto newShardIterator =
std::find_if(shardStats.begin(),
shardStats.end(),
[&newShardId](const ClusterStatistics::ShardStatistics& stat) {
return stat.shardId == newShardId;
});
if (newShardIterator == shardStats.end()) {
return {ErrorCodes::ShardNotFound,
str::stream() << "Unable to find constraints information for shard " << newShardId
<< ". Move to this shard will be disallowed."};
}
return BalancerPolicy::isShardSuitableReceiver(*newShardIterator,
distribution.getTagForChunk(chunk));
}
Status BalancerChunkSelectionPolicyImpl::checkMoveAllowed(OperationContext* opCtx,
const ChunkType& chunk,
const ShardId& newShardId) {
auto shardStatsStatus = _clusterStats->getStats(opCtx);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
auto shardStats = std::move(shardStatsStatus.getValue());
auto routingInfoStatus =
Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfoWithRefresh(opCtx,
chunk.getNS());
if (!routingInfoStatus.isOK()) {
return routingInfoStatus.getStatus();
}
const auto cm = routingInfoStatus.getValue().cm().get();
const auto collInfoStatus = createCollectionDistributionStatus(opCtx, shardStats, cm);
if (!collInfoStatus.isOK()) {
return collInfoStatus.getStatus();
}
const DistributionStatus& distribution = collInfoStatus.getValue();
auto newShardIterator =
std::find_if(shardStats.begin(),
shardStats.end(),
[&newShardId](const ClusterStatistics::ShardStatistics& stat) {
return stat.shardId == newShardId;
});
if (newShardIterator == shardStats.end()) {
return {ErrorCodes::ShardNotFound,
str::stream() << "Unable to find constraints information for shard " << newShardId
<< ". Move to this shard will be disallowed."};
}
return BalancerPolicy::isShardSuitableReceiver(*newShardIterator,
distribution.getTagForChunk(chunk));
}
Status Balancer::rebalanceSingleChunk(OperationContext* txn, const ChunkType& chunk) {
auto migrateStatus = _chunkSelectionPolicy->selectSpecificChunkToMove(txn, chunk);
if (!migrateStatus.isOK()) {
return migrateStatus.getStatus();
}
auto migrateInfo = std::move(migrateStatus.getValue());
if (!migrateInfo) {
LOG(1) << "Unable to find more appropriate location for chunk " << redact(chunk.toString());
return Status::OK();
}
auto balancerConfig = Grid::get(txn)->getBalancerConfiguration();
Status refreshStatus = balancerConfig->refreshAndCheck(txn);
if (!refreshStatus.isOK()) {
return refreshStatus;
}
MigrationManager migrationManager;
auto migrationStatuses = migrationManager.scheduleMigrations(
txn,
{MigrationManager::MigrationRequest(std::move(*migrateInfo),
balancerConfig->getMaxChunkSizeBytes(),
balancerConfig->getSecondaryThrottle(),
balancerConfig->waitForDelete())});
invariant(migrationStatuses.size() == 1);
auto scopedCMStatus = ScopedChunkManager::getExisting(txn, NamespaceString(chunk.getNS()));
if (!scopedCMStatus.isOK()) {
return scopedCMStatus.getStatus();
}
auto scopedCM = std::move(scopedCMStatus.getValue());
ChunkManager* const cm = scopedCM.cm();
cm->reload(txn);
return migrationStatuses.begin()->second;
}
BSONObj buildApplyOpsCmd( const OwnedPointerVector<ChunkType>& chunksToMerge,
const ChunkVersion& currShardVersion,
const ChunkVersion& newMergedVersion ) {
BSONObjBuilder applyOpsCmdB;
BSONArrayBuilder updatesB( applyOpsCmdB.subarrayStart( "applyOps" ) );
// The chunk we'll be "expanding" is the first chunk
const ChunkType* chunkToMerge = *chunksToMerge.begin();
// Fill in details not tracked by metadata
ChunkType mergedChunk;
chunkToMerge->cloneTo( &mergedChunk );
mergedChunk.setName( Chunk::genID( chunkToMerge->getNS(), chunkToMerge->getMin() ) );
mergedChunk.setMax( ( *chunksToMerge.vector().rbegin() )->getMax() );
mergedChunk.setVersion( newMergedVersion );
updatesB.append( buildOpMergeChunk( mergedChunk ) );
// Don't remove chunk we're expanding
OwnedPointerVector<ChunkType>::const_iterator it = chunksToMerge.begin();
for ( ++it; it != chunksToMerge.end(); ++it ) {
ChunkType* chunkToMerge = *it;
chunkToMerge->setName( Chunk::genID( chunkToMerge->getNS(), chunkToMerge->getMin() ) );
updatesB.append( buildOpRemoveChunk( *chunkToMerge ) );
}
updatesB.done();
applyOpsCmdB.append( "preCondition",
buildOpPrecond( chunkToMerge->getNS(),
chunkToMerge->getShard(),
currShardVersion ) );
return applyOpsCmdB.obj();
}