LockResult LockerImpl<IsForMMAPV1>::lockBegin(OperationContext* opCtx,
ResourceId resId,
LockMode mode) {
dassert(!getWaitingResource().isValid());
LockRequest* request;
bool isNew = true;
LockRequestsMap::Iterator it = _requests.find(resId);
if (!it) {
scoped_spinlock scopedLock(_lock);
LockRequestsMap::Iterator itNew = _requests.insert(resId);
itNew->initNew(this, &_notify);
request = itNew.objAddr();
} else {
request = it.objAddr();
isNew = false;
}
// If unlockPending is nonzero, that means a LockRequest already exists for this resource but
// is planned to be released at the end of this WUOW due to two-phase locking. Rather than
// unlocking the existing request, we can reuse it if the existing mode matches the new mode.
if (request->unlockPending && isModeCovered(mode, request->mode)) {
request->unlockPending--;
if (!request->unlockPending) {
_numResourcesToUnlockAtEndUnitOfWork--;
}
return LOCK_OK;
}
// Making this call here will record lock re-acquisitions and conversions as well.
globalStats.recordAcquisition(_id, resId, mode);
_stats.recordAcquisition(resId, mode);
// Give priority to the full modes for global, parallel batch writer mode,
// and flush lock so we don't stall global operations such as shutdown or flush.
const ResourceType resType = resId.getType();
if (resType == RESOURCE_GLOBAL || (IsForMMAPV1 && resId == resourceIdMMAPV1Flush)) {
if (mode == MODE_S || mode == MODE_X) {
request->enqueueAtFront = true;
request->compatibleFirst = true;
}
} else if (resType != RESOURCE_MUTEX) {
// This is all sanity checks that the global and flush locks are always be acquired
// before any other lock has been acquired and they must be in sync with the nesting.
DEV {
const LockRequestsMap::Iterator itGlobal = _requests.find(resourceIdGlobal);
invariant(itGlobal->recursiveCount > 0);
invariant(itGlobal->mode != MODE_NONE);
// Check the MMAP V1 flush lock is held in the appropriate mode
invariant(!IsForMMAPV1 ||
isLockHeldForMode(resourceIdMMAPV1Flush, _getModeForMMAPV1FlushLock()));
};
}
bool LockerImpl<IsForMMAPV1>::isLockHeldForMode(ResourceId resId, LockMode mode) const {
return isModeCovered(mode, getLockMode(resId));
}
