virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
if ( cmdObj.firstElement().type() != Array ) {
errmsg = "ops has to be an array";
return false;
}
BSONObj ops = cmdObj.firstElement().Obj();
{
// check input
BSONObjIterator i( ops );
while ( i.more() ) {
BSONElement e = i.next();
if (!_checkOperation(e, errmsg)) {
return false;
}
}
}
// SERVER-4328 todo : is global ok or does this take a long time? i believe multiple
// ns used so locking individually requires more analysis
Lock::GlobalWrite globalWriteLock(txn->lockState());
DBDirectClient db(txn);
// Preconditions check reads the database state, so needs to be done locked
if ( cmdObj["preCondition"].type() == Array ) {
BSONObjIterator i( cmdObj["preCondition"].Obj() );
while ( i.more() ) {
BSONObj f = i.next().Obj();
DBDirectClient db( txn );
BSONObj realres = db.findOne( f["ns"].String() , f["q"].Obj() );
// Apply-ops would never have a $where matcher, so use the default callback,
// which will throw an error if $where is found.
Matcher m(f["res"].Obj());
if ( ! m.matches( realres ) ) {
result.append( "got" , realres );
result.append( "whatFailed" , f );
errmsg = "pre-condition failed";
return false;
}
}
}
// apply
int num = 0;
int errors = 0;
BSONObjIterator i( ops );
BSONArrayBuilder ab;
const bool alwaysUpsert = cmdObj.hasField("alwaysUpsert") ?
cmdObj["alwaysUpsert"].trueValue() : true;
while ( i.more() ) {
BSONElement e = i.next();
const BSONObj& temp = e.Obj();
// Ignore 'n' operations.
const char *opType = temp["op"].valuestrsafe();
if (*opType == 'n') continue;
string ns = temp["ns"].String();
// Run operations under a nested lock as a hack to prevent yielding.
//
// The list of operations is supposed to be applied atomically; yielding
// would break atomicity by allowing an interruption or a shutdown to occur
// after only some operations are applied. We are already locked globally
// at this point, so taking a DBLock on the namespace creates a nested lock,
// and yields are disallowed for operations that hold a nested lock.
//
// We do not have a wrapping WriteUnitOfWork so it is possible for a journal
// commit to happen with a subset of ops applied.
// TODO figure out what to do about this.
Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), MODE_X);
invariant(txn->lockState()->isRecursive());
Client::Context ctx(txn, ns);
bool failed = repl::applyOperation_inlock(txn,
ctx.db(),
temp,
false,
alwaysUpsert);
ab.append(!failed);
if ( failed )
errors++;
num++;
logOpForDbHash(ns.c_str());
}
result.append( "applied" , num );
result.append( "results" , ab.arr() );
if ( ! fromRepl ) {
// We want this applied atomically on slaves
// so we re-wrap without the pre-condition for speed
string tempNS = str::stream() << dbname << ".$cmd";
// TODO: possibly use mutable BSON to remove preCondition field
// once it is available
BSONObjIterator iter(cmdObj);
BSONObjBuilder cmdBuilder;
while (iter.more()) {
BSONElement elem(iter.next());
if (strcmp(elem.fieldName(), "preCondition") != 0) {
cmdBuilder.append(elem);
}
}
// We currently always logOp the command regardless of whether the individial ops
// succeeded and rely on any failures to also happen on secondaries. This isn't
// perfect, but it's what the command has always done and is part of its "correct"
// behavior.
WriteUnitOfWork wunit(txn);
repl::logOp(txn, "c", tempNS.c_str(), cmdBuilder.done());
wunit.commit();
}
if (errors != 0) {
return false;
}
return true;
}
virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
if ( cmdObj.firstElement().type() != Array ) {
errmsg = "ops has to be an array";
return false;
}
BSONObj ops = cmdObj.firstElement().Obj();
{
// check input
BSONObjIterator i( ops );
while ( i.more() ) {
BSONElement e = i.next();
if (!_checkOperation(e, errmsg)) {
return false;
}
}
}
// SERVER-4328 todo : is global ok or does this take a long time? i believe multiple
// ns used so locking individually requires more analysis
ScopedTransaction scopedXact(txn, MODE_X);
Lock::GlobalWrite globalWriteLock(txn->lockState());
if (!fromRepl &&
!repl::getGlobalReplicationCoordinator()->canAcceptWritesForDatabase(dbname)) {
return appendCommandStatus(result, Status(ErrorCodes::NotMaster, str::stream()
<< "Not primary while applying ops to database " << dbname));
}
// Preconditions check reads the database state, so needs to be done locked
if ( cmdObj["preCondition"].type() == Array ) {
BSONObjIterator i( cmdObj["preCondition"].Obj() );
while ( i.more() ) {
BSONObj f = i.next().Obj();
DBDirectClient db( txn );
BSONObj realres = db.findOne( f["ns"].String() , f["q"].Obj() );
// Apply-ops would never have a $where matcher, so use the default callback,
// which will throw an error if $where is found.
Matcher m(f["res"].Obj());
if ( ! m.matches( realres ) ) {
result.append( "got" , realres );
result.append( "whatFailed" , f );
errmsg = "pre-condition failed";
return false;
}
}
}
// apply
int num = 0;
int errors = 0;
BSONObjIterator i( ops );
BSONArrayBuilder ab;
const bool alwaysUpsert = cmdObj.hasField("alwaysUpsert") ?
cmdObj["alwaysUpsert"].trueValue() : true;
while ( i.more() ) {
BSONElement e = i.next();
const BSONObj& temp = e.Obj();
// Ignore 'n' operations.
const char *opType = temp["op"].valuestrsafe();
if (*opType == 'n') continue;
const string ns = temp["ns"].String();
// Run operations under a nested lock as a hack to prevent yielding.
//
// The list of operations is supposed to be applied atomically; yielding
// would break atomicity by allowing an interruption or a shutdown to occur
// after only some operations are applied. We are already locked globally
// at this point, so taking a DBLock on the namespace creates a nested lock,
// and yields are disallowed for operations that hold a nested lock.
//
// We do not have a wrapping WriteUnitOfWork so it is possible for a journal
// commit to happen with a subset of ops applied.
// TODO figure out what to do about this.
Lock::GlobalWrite globalWriteLockDisallowTempRelease(txn->lockState());
// Ensures that yielding will not happen (see the comment above).
DEV {
Locker::LockSnapshot lockSnapshot;
invariant(!txn->lockState()->saveLockStateAndUnlock(&lockSnapshot));
};
OldClientContext ctx(txn, ns);
Status status(ErrorCodes::InternalError, "");
while (true) {
try {
// We assume that in the WriteConflict retry case, either the op rolls back
// any changes it makes or is otherwise safe to rerun.
status =
repl::applyOperation_inlock(txn, ctx.db(), temp, false, alwaysUpsert);
break;
}
catch (const WriteConflictException& wce) {
LOG(2) << "WriteConflictException in applyOps command, retrying.";
txn->recoveryUnit()->commitAndRestart();
continue;
}
}
ab.append(status.isOK());
if (!status.isOK()) {
errors++;
}
num++;
WriteUnitOfWork wuow(txn);
logOpForDbHash(txn, ns.c_str());
wuow.commit();
}
result.append( "applied" , num );
result.append( "results" , ab.arr() );
if ( ! fromRepl ) {
// We want this applied atomically on slaves
// so we re-wrap without the pre-condition for speed
string tempNS = str::stream() << dbname << ".$cmd";
// TODO: possibly use mutable BSON to remove preCondition field
// once it is available
BSONObjIterator iter(cmdObj);
BSONObjBuilder cmdBuilder;
while (iter.more()) {
BSONElement elem(iter.next());
if (strcmp(elem.fieldName(), "preCondition") != 0) {
cmdBuilder.append(elem);
}
}
const BSONObj cmdRewritten = cmdBuilder.done();
// We currently always logOp the command regardless of whether the individial ops
// succeeded and rely on any failures to also happen on secondaries. This isn't
// perfect, but it's what the command has always done and is part of its "correct"
// behavior.
while (true) {
try {
WriteUnitOfWork wunit(txn);
getGlobalEnvironment()->getOpObserver()->onApplyOps(txn,
tempNS,
cmdRewritten);
wunit.commit();
break;
}
catch (const WriteConflictException& wce) {
LOG(2) <<
"WriteConflictException while logging applyOps command, retrying.";
txn->recoveryUnit()->commitAndRestart();
continue;
}
}
}
if (errors != 0) {
return false;
}
return true;
}
