void LockerImpl<IsForMMAPV1>::lockMMAPV1Flush() {
if (!IsForMMAPV1)
return;
// The flush lock always has a reference count of 1, because it is dropped at the end of
// each write unit of work in order to allow the flush thread to run. See the comments in
// the header for information on how the MMAP V1 journaling system works.
LockRequest* globalLockRequest = _requests.find(resourceIdGlobal).objAddr();
if (globalLockRequest->recursiveCount == 1) {
invariant(LOCK_OK == lock(resourceIdMMAPV1Flush, _getModeForMMAPV1FlushLock()));
}
dassert(getLockMode(resourceIdMMAPV1Flush) == _getModeForMMAPV1FlushLock());
}
void LockerImpl<IsForMMAPV1>::restoreLockState(OperationContext* opCtx,
const Locker::LockSnapshot& state) {
// We shouldn't be saving and restoring lock state from inside a WriteUnitOfWork.
invariant(!inAWriteUnitOfWork());
invariant(_modeForTicket == MODE_NONE);
std::vector<OneLock>::const_iterator it = state.locks.begin();
// If we locked the PBWM, it must be locked before the resourceIdGlobal resource.
if (it != state.locks.end() && it->resourceId == resourceIdParallelBatchWriterMode) {
invariant(LOCK_OK == lock(opCtx, it->resourceId, it->mode));
it++;
}
invariant(LOCK_OK == lockGlobal(opCtx, state.globalMode));
for (; it != state.locks.end(); it++) {
// This is a sanity check that lockGlobal restored the MMAP V1 flush lock in the
// expected mode.
if (IsForMMAPV1 && (it->resourceId == resourceIdMMAPV1Flush)) {
invariant(it->mode == _getModeForMMAPV1FlushLock());
} else {
invariant(LOCK_OK == lock(it->resourceId, it->mode));
}
}
invariant(_modeForTicket != MODE_NONE);
}
void LockerImpl<IsForMMAPV1>::endWriteUnitOfWork() {
invariant(_wuowNestingLevel > 0);
if (--_wuowNestingLevel > 0) {
// Don't do anything unless leaving outermost WUOW.
return;
}
LockRequestsMap::Iterator it = _requests.begin();
while (_numResourcesToUnlockAtEndUnitOfWork > 0) {
if (it->unlockPending) {
invariant(!it.finished());
_numResourcesToUnlockAtEndUnitOfWork--;
}
while (it->unlockPending > 0) {
// If a lock is converted, unlock() may be called multiple times on a resource within
// the same WriteUnitOfWork. All such unlock() requests must thus be fulfilled here.
it->unlockPending--;
unlock(it.key());
}
it.next();
}
// For MMAP V1, we need to yield the flush lock so that the flush thread can run
if (IsForMMAPV1) {
invariant(unlock(resourceIdMMAPV1Flush));
invariant(LOCK_OK == lock(resourceIdMMAPV1Flush, _getModeForMMAPV1FlushLock()));
}
}
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()));
};
}
LockResult LockerImpl<IsForMMAPV1>::lockBegin(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;
}
// 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()));
};
}
void LockerImpl<IsForMMAPV1>::endWriteUnitOfWork() {
invariant(_wuowNestingLevel > 0);
if (--_wuowNestingLevel > 0) {
// Don't do anything unless leaving outermost WUOW.
return;
}
while (!_resourcesToUnlockAtEndOfUnitOfWork.empty()) {
unlock(_resourcesToUnlockAtEndOfUnitOfWork.front());
_resourcesToUnlockAtEndOfUnitOfWork.pop();
}
// For MMAP V1, we need to yield the flush lock so that the flush thread can run
if (IsForMMAPV1) {
invariant(unlock(resourceIdMMAPV1Flush));
invariant(LOCK_OK == lock(resourceIdMMAPV1Flush, _getModeForMMAPV1FlushLock()));
}
}