StatusWith<Shard::QueryResponse> ShardLocal::_exhaustiveFindOnConfig(
OperationContext* txn,
const ReadPreferenceSetting& readPref,
const repl::ReadConcernLevel& readConcernLevel,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
boost::optional<long long> limit) {
auto replCoord = repl::ReplicationCoordinator::get(txn);
if (readConcernLevel == repl::ReadConcernLevel::kMajorityReadConcern) {
// Set up operation context with majority read snapshot so correct optime can be retrieved.
Status status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
// Wait for any writes performed by this ShardLocal instance to be committed and visible.
Status readConcernStatus = replCoord->waitUntilOpTimeForRead(
txn, repl::ReadConcernArgs{_getLastOpTime(), readConcernLevel});
if (!readConcernStatus.isOK()) {
return readConcernStatus;
}
// Inform the storage engine to read from the committed snapshot for the rest of this
// operation.
status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
if (!status.isOK()) {
return status;
}
} else {
invariant(readConcernLevel == repl::ReadConcernLevel::kLocalReadConcern);
}
DBDirectClient client(txn);
Query fullQuery(query);
if (!sort.isEmpty()) {
fullQuery.sort(sort);
}
fullQuery.readPref(readPref.pref, BSONArray());
try {
std::unique_ptr<DBClientCursor> cursor =
client.query(nss.ns().c_str(), fullQuery, limit.get_value_or(0));
if (!cursor) {
return {ErrorCodes::OperationFailed,
str::stream() << "Failed to establish a cursor for reading " << nss.ns()
<< " from local storage"};
}
std::vector<BSONObj> documentVector;
while (cursor->more()) {
BSONObj document = cursor->nextSafe().getOwned();
documentVector.push_back(std::move(document));
}
return Shard::QueryResponse{std::move(documentVector),
replCoord->getCurrentCommittedSnapshotOpTime()};
} catch (const DBException& ex) {
return ex.toStatus();
}
}
StatusWith<Shard::QueryResponse> ShardLocal::_exhaustiveFindOnConfig(
OperationContext* txn,
const ReadPreferenceSetting& readPref,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
boost::optional<long long> limit) {
// Set up operation context with majority read snapshot so correct optime can be retrieved.
Status status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
auto replCoord = repl::ReplicationCoordinator::get(txn);
// Ensure timeout is set on the txn so we don't wait forever for the snapshot.
// TODO (SERVER-18277): Remove this
CurOp::get(txn)->ensureStarted();
// Wait until a snapshot is available.
while (status == ErrorCodes::ReadConcernMajorityNotAvailableYet) {
LOG(1) << "Waiting for ReadFromMajorityCommittedSnapshot to become available";
replCoord->waitUntilSnapshotCommitted(txn, SnapshotName::min());
status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
}
if (!status.isOK()) {
return status;
}
DBDirectClient client(txn);
Query fullQuery(query);
if (!sort.isEmpty()) {
fullQuery.sort(sort);
}
fullQuery.readPref(readPref.pref, BSONArray());
try {
std::unique_ptr<DBClientCursor> cursor =
client.query(nss.ns().c_str(), fullQuery, limit.get_value_or(0));
if (!cursor) {
return {ErrorCodes::OperationFailed,
str::stream() << "Failed to establish a cursor for reading " << nss.ns()
<< " from local storage"};
}
std::vector<BSONObj> documentVector;
while (cursor->more()) {
BSONObj document = cursor->nextSafe().getOwned();
documentVector.push_back(std::move(document));
}
return Shard::QueryResponse{std::move(documentVector),
replCoord->getCurrentCommittedSnapshotOpTime()};
} catch (const DBException& ex) {
return ex.toStatus();
}
}