// Lock conflict matrix tests
static void checkConflict(LockMode existingMode, LockMode newMode, bool hasConflict) {
LockManager lockMgr;
const ResourceId resId(RESOURCE_COLLECTION, std::string("TestDB.collection"));
MMAPV1LockerImpl lockerExisting;
TrackingLockGrantNotification notifyExisting;
LockRequest requestExisting;
requestExisting.initNew(&lockerExisting, ¬ifyExisting);
ASSERT(LOCK_OK == lockMgr.lock(resId, &requestExisting, existingMode));
MMAPV1LockerImpl lockerNew;
TrackingLockGrantNotification notifyNew;
LockRequest requestNew;
requestNew.initNew(&lockerNew, ¬ifyNew);
LockResult result = lockMgr.lock(resId, &requestNew, newMode);
if (hasConflict) {
ASSERT_EQUALS(LOCK_WAITING, result);
} else {
ASSERT_EQUALS(LOCK_OK, result);
}
lockMgr.unlock(&requestNew);
lockMgr.unlock(&requestExisting);
}
TEST(LockManager, GrantRecursiveNonCompatibleConvertDown) {
LockManager lockMgr;
const ResourceId resId(RESOURCE_COLLECTION, std::string("TestDB.collection"));
LockState locker;
TrackingLockGrantNotification notify;
LockRequest request;
request.initNew(&locker, ¬ify);
ASSERT(LOCK_OK == lockMgr.lock(resId, &request, MODE_X));
ASSERT(request.mode == MODE_X);
ASSERT(request.recursiveCount == 1);
ASSERT(notify.numNotifies == 0);
// Acquire again, in *non-compatible*, but less strict mode
ASSERT(LOCK_OK == lockMgr.lock(resId, &request, MODE_S));
ASSERT(request.mode == MODE_X);
ASSERT(request.recursiveCount == 2);
ASSERT(notify.numNotifies == 0);
// Release first acquire
lockMgr.unlock(&request);
ASSERT(request.mode == MODE_X);
ASSERT(request.recursiveCount == 1);
// Release second acquire
lockMgr.unlock(&request);
ASSERT(request.recursiveCount == 0);
}
LockResult LockerImpl::lock(const ResourceId& resId, LockMode mode, unsigned timeoutMs) {
_notify.clear();
_lock.lock();
LockRequest* request = _find(resId);
if (request == NULL) {
request = new LockRequest();
request->initNew(resId, this, &_notify);
_requests.insert(LockRequestsPair(resId, request));
}
else {
invariant(request->recursiveCount > 0);
request->notify = &_notify;
}
_lock.unlock();
// Methods on the Locker class are always called single-threadly, so it is safe to release
// the spin lock, which protects the Locker here. The only thing which could alter the
// state of the request is deadlock detection, which however would synchronize on the
// LockManager calls.
LockResult result = globalLockManagerPtr->lock(resId, request, mode);
if (result == LOCK_WAITING) {
// Under MMAP V1 engine a deadlock can occur if a thread goes to sleep waiting on DB
// lock, while holding the flush lock, so it has to be released. This is only correct
// to do if not in a write unit of work.
bool unlockedFlushLock = false;
if (!inAWriteUnitOfWork() &&
(resId != resourceIdGlobal) &&
(resId != resourceIdMMAPV1Flush) &&
(resId != resourceIdLocalDB)) {
invariant(unlock(resourceIdMMAPV1Flush));
unlockedFlushLock = true;
}
// Do the blocking outside of the flush lock (if not in a write unit of work)
result = _notify.wait(timeoutMs);
if (unlockedFlushLock) {
// We cannot obey the timeout here, because it is not correct to return from the
// lock request with the flush lock released.
invariant(LOCK_OK ==
lock(resourceIdMMAPV1Flush, getLockMode(resourceIdGlobal), UINT_MAX));
}
}
if (result != LOCK_OK) {
// Can only be LOCK_TIMEOUT, because the lock manager does not return any other errors
// at this point. Could be LOCK_DEADLOCK, when deadlock detection is implemented.
invariant(result == LOCK_TIMEOUT);
invariant(_unlockAndUpdateRequestsList(resId, request));
}
return result;
}
TEST(LockManager, Grant) {
LockManager lockMgr;
const ResourceId resId(RESOURCE_COLLECTION, std::string("TestDB.collection"));
MMAPV1LockerImpl locker;
TrackingLockGrantNotification notify;
LockRequest request;
request.initNew(&locker, ¬ify);
ASSERT(LOCK_OK == lockMgr.lock(resId, &request, MODE_S));
ASSERT(request.mode == MODE_S);
ASSERT(request.recursiveCount == 1);
ASSERT(notify.numNotifies == 0);
lockMgr.unlock(&request);
ASSERT(request.recursiveCount == 0);
}
void LockManager::run() {
deadlock_detector_->start();
const std::uint64_t kMaxTryIncoming =
static_cast<std::uint64_t>(FLAGS_max_try_incoming);
const std::uint64_t kMaxTryInner =
static_cast<std::uint64_t>(FLAGS_max_try_incoming);
while (true) {
for (std::uint64_t tries = 0; tries < kMaxTryIncoming; ++tries) {
if (!incoming_requests_.empty()) {
const LockRequest request = incoming_requests_.popOne();
if (request.getRequestType() == RequestType::kReleaseLocks) {
CHECK(releaseAllLocks(request.getTransactionId()))
<< "Unexpected condition occured.";
} else if (acquireLock(request.getTransactionId(),
request.getResourceId(),
request.getAccessMode())) {
LOG(INFO) << "Transaction "
<< std::to_string(request.getTransactionId())
<< " is waiting " + request.getResourceId().toString();
inner_pending_requests_.push(request);
} else {
LOG(INFO) << "Transaction "
<< std::to_string(request.getTransactionId())
<< " acquired " + request.getResourceId().toString();
permitted_requests_.push(request);
}
}
}
for (std::uint64_t tries = 0; tries < kMaxTryInner; ++tries) {
if (!inner_pending_requests_.empty()) {
const LockRequest request = inner_pending_requests_.front();
if (acquireLock(request.getTransactionId(), request.getResourceId(),
request.getAccessMode())) {
inner_pending_requests_.pop();
permitted_requests_.push(request);
}
}
}
// Resolve deadlocks.
killVictims();
}
}
