StatusWith<MigrateInfoVector> BalancerChunkSelectionPolicyImpl::selectChunksToMove(
OperationContext* opCtx) {
auto shardStatsStatus = _clusterStats->getStats(opCtx);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
const auto shardStats = std::move(shardStatsStatus.getValue());
if (shardStats.size() < 2) {
return MigrateInfoVector{};
}
auto swCollections = Grid::get(opCtx)->catalogClient()->getCollections(opCtx, nullptr, nullptr);
if (!swCollections.isOK()) {
return swCollections.getStatus();
}
auto& collections = swCollections.getValue();
if (collections.empty()) {
return MigrateInfoVector{};
}
MigrateInfoVector candidateChunks;
std::set<ShardId> usedShards;
std::shuffle(collections.begin(), collections.end(), _random);
for (const auto& coll : collections) {
if (coll.getDropped()) {
continue;
}
const NamespaceString nss(coll.getNs());
if (!coll.getAllowBalance()) {
LOG(1) << "Not balancing collection " << nss << "; explicitly disabled.";
continue;
}
auto candidatesStatus =
_getMigrateCandidatesForCollection(opCtx, nss, shardStats, &usedShards);
if (candidatesStatus == ErrorCodes::NamespaceNotFound) {
// Namespace got dropped before we managed to get to it, so just skip it
continue;
} else if (!candidatesStatus.isOK()) {
warning() << "Unable to balance collection " << nss.ns()
<< causedBy(candidatesStatus.getStatus());
continue;
}
candidateChunks.insert(candidateChunks.end(),
std::make_move_iterator(candidatesStatus.getValue().begin()),
std::make_move_iterator(candidatesStatus.getValue().end()));
}
return candidateChunks;
}
StatusWith<MigrateInfoVector> BalancerChunkSelectionPolicyImpl::selectChunksToMove(
OperationContext* txn, bool aggressiveBalanceHint) {
auto shardStatsStatus = _clusterStats->getStats(txn);
if (!shardStatsStatus.isOK()) {
return shardStatsStatus.getStatus();
}
const auto shardStats = std::move(shardStatsStatus.getValue());
if (shardStats.size() < 2) {
return MigrateInfoVector{};
}
vector<CollectionType> collections;
Status collsStatus =
Grid::get(txn)->catalogClient(txn)->getCollections(txn, nullptr, &collections, nullptr);
if (!collsStatus.isOK()) {
return collsStatus;
}
if (collections.empty()) {
return MigrateInfoVector{};
}
MigrateInfoVector candidateChunks;
for (const auto& coll : collections) {
const NamespaceString nss(coll.getNs());
if (!coll.getAllowBalance()) {
LOG(1) << "Not balancing collection " << nss << "; explicitly disabled.";
continue;
}
auto candidatesStatus =
_getMigrateCandidatesForCollection(txn, nss, shardStats, aggressiveBalanceHint);
if (candidatesStatus == ErrorCodes::NamespaceNotFound) {
// Namespace got dropped before we managed to get to it, so just skip it
continue;
} else if (!candidatesStatus.isOK()) {
warning() << "Unable to balance collection " << nss.ns()
<< causedBy(candidatesStatus.getStatus());
continue;
}
candidateChunks.insert(candidateChunks.end(),
std::make_move_iterator(candidatesStatus.getValue().begin()),
std::make_move_iterator(candidatesStatus.getValue().end()));
}
return candidateChunks;
}
