Status createCollectionForApplyOps(OperationContext* opCtx,
const std::string& dbName,
const BSONElement& ui,
const BSONObj& cmdObj,
const BSONObj& idIndex) {
invariant(opCtx->lockState()->isDbLockedForMode(dbName, MODE_X));
auto db = dbHolder().get(opCtx, dbName);
const NamespaceString newCollName(Command::parseNsCollectionRequired(dbName, cmdObj));
auto newCmd = cmdObj;
// If a UUID is given, see if we need to rename a collection out of the way, and whether the
// collection already exists under a different name. If so, rename it into place. As this is
// done during replay of the oplog, the operations do not need to be atomic, just idempotent.
// We need to do the renaming part in a separate transaction, as we cannot transactionally
// create a database on MMAPv1, which could result in createCollection failing if the database
// does not yet exist.
if (ui.ok()) {
// Return an optional, indicating whether we need to early return (if the collection already
// exists, or in case of an error).
using Result = boost::optional<Status>;
auto result =
writeConflictRetry(opCtx, "createCollectionForApplyOps", newCollName.ns(), [&] {
WriteUnitOfWork wunit(opCtx);
// Options need the field to be named "uuid", so parse/recreate.
auto uuid = uassertStatusOK(UUID::parse(ui));
uassert(ErrorCodes::InvalidUUID,
"Invalid UUID in applyOps create command: " + uuid.toString(),
uuid.isRFC4122v4());
auto& catalog = UUIDCatalog::get(opCtx);
auto currentName = catalog.lookupNSSByUUID(uuid);
OpObserver* opObserver = getGlobalServiceContext()->getOpObserver();
if (currentName == newCollName)
return Result(Status::OK());
// In the case of oplog replay, a future command may have created or renamed a
// collection with that same name. In that case, renaming this future collection to
// a random temporary name is correct: once all entries are replayed no temporary
// names will remain. On MMAPv1 the rename can result in index names that are too
// long. However this should only happen for initial sync and "resync collection"
// for rollback, so we can let the error propagate resulting in an abort and restart
// of the initial sync or result in rollback to fassert, requiring a resync of that
// node.
const bool stayTemp = true;
if (auto futureColl = db ? db->getCollection(opCtx, newCollName) : nullptr) {
auto tmpNameResult = db->makeUniqueCollectionNamespace(opCtx, "tmp%%%%%");
if (!tmpNameResult.isOK()) {
return Result(Status(tmpNameResult.getStatus().code(),
str::stream() << "Cannot generate temporary "
"collection namespace for applyOps "
"create command: collection: "
<< newCollName.ns()
<< ". error: "
<< tmpNameResult.getStatus().reason()));
}
const auto& tmpName = tmpNameResult.getValue();
Status status =
db->renameCollection(opCtx, newCollName.ns(), tmpName.ns(), stayTemp);
if (!status.isOK())
return Result(status);
opObserver->onRenameCollection(opCtx,
newCollName,
tmpName,
futureColl->uuid(),
/*dropTarget*/ false,
/*dropTargetUUID*/ {},
stayTemp);
}
// If the collection with the requested UUID already exists, but with a different
// name, just rename it to 'newCollName'.
if (catalog.lookupCollectionByUUID(uuid)) {
Status status =
db->renameCollection(opCtx, currentName.ns(), newCollName.ns(), stayTemp);
if (!status.isOK())
return Result(status);
opObserver->onRenameCollection(opCtx,
currentName,
newCollName,
uuid,
/*dropTarget*/ false,
/*dropTargetUUID*/ {},
stayTemp);
wunit.commit();
return Result(Status::OK());
}
// A new collection with the specific UUID must be created, so add the UUID to the
// creation options. Regular user collection creation commands cannot do this.
auto uuidObj = uuid.toBSON();
newCmd = cmdObj.addField(uuidObj.firstElement());
wunit.commit();
return Result(boost::none);
});
if (result) {
return *result;
}
}
return createCollection(
opCtx, newCollName, newCmd, idIndex, CollectionOptions::parseForStorage);
}
