/**
* Apply the read concern from the cursor to this operation.
*/
void applyCursorReadConcern(OperationContext* opCtx, repl::ReadConcernArgs rcArgs) {
const auto replicationMode = repl::ReplicationCoordinator::get(opCtx)->getReplicationMode();
// Select the appropriate read source.
if (replicationMode == repl::ReplicationCoordinator::modeReplSet &&
rcArgs.getLevel() == repl::ReadConcernLevel::kMajorityReadConcern) {
switch (rcArgs.getMajorityReadMechanism()) {
case repl::ReadConcernArgs::MajorityReadMechanism::kMajoritySnapshot: {
// Make sure we read from the majority snapshot.
opCtx->recoveryUnit()->setTimestampReadSource(
RecoveryUnit::ReadSource::kMajorityCommitted);
uassertStatusOK(opCtx->recoveryUnit()->obtainMajorityCommittedSnapshot());
break;
}
case repl::ReadConcernArgs::MajorityReadMechanism::kSpeculative: {
// Mark the operation as speculative and select the correct read source.
repl::SpeculativeMajorityReadInfo::get(opCtx).setIsSpeculativeRead();
opCtx->recoveryUnit()->setTimestampReadSource(RecoveryUnit::ReadSource::kNoOverlap);
break;
}
}
}
// For cursor commands that take locks internally, the read concern on the
// OperationContext may affect the timestamp read source selected by the storage engine.
// We place the cursor read concern onto the OperationContext so the lock acquisition
// respects the cursor's read concern.
{
stdx::lock_guard<Client> lk(*opCtx->getClient());
repl::ReadConcernArgs::get(opCtx) = rcArgs;
}
}
