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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kDefault
#include "mongo/platform/basic.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include <memory>
#include <string>
#include <vector>
#include "mongo/db/catalog/collection_catalog.h"
#include "mongo/db/concurrency/flow_control_ticketholder.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/service_context.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/stacktrace.h"
#include "mongo/util/str.h"
namespace mongo {
Lock::TempRelease::TempRelease(Locker* lockState)
: _lockState(lockState),
_lockSnapshot(),
_locksReleased(_lockState->saveLockStateAndUnlock(&_lockSnapshot)) {}
Lock::TempRelease::~TempRelease() {
if (_locksReleased) {
invariant(!_lockState->isLocked());
_lockState->restoreLockState(_lockSnapshot);
}
}
namespace {
/**
* ResourceMutexes can be constructed during initialization, thus the code must ensure the vector
* of labels is constructed before items are added to it. This factory encapsulates all members
* that need to be initialized before first use. A pointer is allocated to an instance of this
* factory and the first call will construct an instance.
*/
class ResourceIdFactory {
public:
static ResourceId newResourceIdForMutex(std::string resourceLabel) {
ensureInitialized();
return resourceIdFactory->_newResourceIdForMutex(std::move(resourceLabel));
}
static std::string nameForId(ResourceId resourceId) {
stdx::lock_guard<Latch> lk(resourceIdFactory->labelsMutex);
return resourceIdFactory->labels.at(resourceId.getHashId());
}
/**
* Must be called in a single-threaded context (e.g: program initialization) before the factory
* is safe to use in a multi-threaded context.
*/
static void ensureInitialized() {
if (!resourceIdFactory) {
resourceIdFactory = new ResourceIdFactory();
}
}
private:
ResourceId _newResourceIdForMutex(std::string resourceLabel) {
stdx::lock_guard<Latch> lk(labelsMutex);
invariant(nextId == labels.size());
labels.push_back(std::move(resourceLabel));
return ResourceId(RESOURCE_MUTEX, nextId++);
}
static ResourceIdFactory* resourceIdFactory;
std::uint64_t nextId = 0;
std::vector<std::string> labels;
Mutex labelsMutex = MONGO_MAKE_LATCH("ResourceIdFactory::labelsMutex");
};
ResourceIdFactory* ResourceIdFactory::resourceIdFactory;
/**
* Guarantees `ResourceIdFactory::ensureInitialized` is called at least once during initialization.
*/
struct ResourceIdFactoryInitializer {
ResourceIdFactoryInitializer() {
ResourceIdFactory::ensureInitialized();
}
} resourceIdFactoryInitializer;
} // namespace
Lock::ResourceMutex::ResourceMutex(std::string resourceLabel)
: _rid(ResourceIdFactory::newResourceIdForMutex(std::move(resourceLabel))) {}
std::string Lock::ResourceMutex::getName(ResourceId resourceId) {
invariant(resourceId.getType() == RESOURCE_MUTEX);
return ResourceIdFactory::nameForId(resourceId);
}
bool Lock::ResourceMutex::isExclusivelyLocked(Locker* locker) {
return locker->isLockHeldForMode(_rid, MODE_X);
}
bool Lock::ResourceMutex::isAtLeastReadLocked(Locker* locker) {
return locker->isLockHeldForMode(_rid, MODE_IS);
}
Lock::GlobalLock::GlobalLock(OperationContext* opCtx,
LockMode lockMode,
Date_t deadline,
InterruptBehavior behavior,
bool skipRSTLLock)
: _opCtx(opCtx),
_result(LOCK_INVALID),
_pbwm(opCtx->lockState(), resourceIdParallelBatchWriterMode),
_interruptBehavior(behavior),
_skipRSTLLock(skipRSTLLock),
_isOutermostLock(!opCtx->lockState()->isLocked()) {
_opCtx->lockState()->getFlowControlTicket(_opCtx, lockMode);
try {
if (_opCtx->lockState()->shouldConflictWithSecondaryBatchApplication()) {
_pbwm.lock(opCtx, MODE_IS, deadline);
}
auto unlockPBWM = makeGuard([this] {
if (_opCtx->lockState()->shouldConflictWithSecondaryBatchApplication()) {
_pbwm.unlock();
}
});
_result = LOCK_INVALID;
if (skipRSTLLock) {
_takeGlobalLockOnly(lockMode, deadline);
} else {
_takeGlobalAndRSTLLocks(lockMode, deadline);
}
_result = LOCK_OK;
unlockPBWM.dismiss();
} catch (const ExceptionForCat<ErrorCategory::Interruption>&) {
// The kLeaveUnlocked behavior suppresses this exception.
if (_interruptBehavior == InterruptBehavior::kThrow)
throw;
}
auto acquiredLockMode = _opCtx->lockState()->getLockMode(resourceIdGlobal);
_opCtx->lockState()->setGlobalLockTakenInMode(acquiredLockMode);
}
void Lock::GlobalLock::_takeGlobalLockOnly(LockMode lockMode, Date_t deadline) {
_opCtx->lockState()->lockGlobal(_opCtx, lockMode, deadline);
}
void Lock::GlobalLock::_takeGlobalAndRSTLLocks(LockMode lockMode, Date_t deadline) {
_opCtx->lockState()->lock(_opCtx, resourceIdReplicationStateTransitionLock, MODE_IX, deadline);
auto unlockRSTL = makeGuard(
[this] { _opCtx->lockState()->unlock(resourceIdReplicationStateTransitionLock); });
_opCtx->lockState()->lockGlobal(_opCtx, lockMode, deadline);
unlockRSTL.dismiss();
}
Lock::GlobalLock::GlobalLock(GlobalLock&& otherLock)
: _opCtx(otherLock._opCtx),
_result(otherLock._result),
_pbwm(std::move(otherLock._pbwm)),
_interruptBehavior(otherLock._interruptBehavior),
_skipRSTLLock(otherLock._skipRSTLLock),
_isOutermostLock(otherLock._isOutermostLock) {
// Mark as moved so the destructor doesn't invalidate the newly-constructed lock.
otherLock._result = LOCK_INVALID;
}
void Lock::GlobalLock::_unlock() {
_opCtx->lockState()->unlockGlobal();
_result = LOCK_INVALID;
}
Lock::DBLock::DBLock(OperationContext* opCtx, StringData db, LockMode mode, Date_t deadline)
: _id(RESOURCE_DATABASE, db),
_opCtx(opCtx),
_result(LOCK_INVALID),
_mode(mode),
_globalLock(
opCtx, isSharedLockMode(_mode) ? MODE_IS : MODE_IX, deadline, InterruptBehavior::kThrow) {
massert(28539, "need a valid database name", !db.empty() && nsIsDbOnly(db));
_opCtx->lockState()->lock(_opCtx, _id, _mode, deadline);
_result = LOCK_OK;
}
Lock::DBLock::DBLock(DBLock&& otherLock)
: _id(otherLock._id),
_opCtx(otherLock._opCtx),
_result(otherLock._result),
_mode(otherLock._mode),
_globalLock(std::move(otherLock._globalLock)) {
// Mark as moved so the destructor doesn't invalidate the newly-constructed lock.
otherLock._result = LOCK_INVALID;
}
Lock::DBLock::~DBLock() {
if (isLocked()) {
_opCtx->lockState()->unlock(_id);
}
}
void Lock::DBLock::relockWithMode(LockMode newMode) {
// 2PL would delay the unlocking
invariant(!_opCtx->lockState()->inAWriteUnitOfWork());
// Not allowed to change global intent, so check when going from shared to exclusive.
if (isSharedLockMode(_mode) && !isSharedLockMode(newMode))
invariant(_opCtx->lockState()->isWriteLocked());
_opCtx->lockState()->unlock(_id);
_mode = newMode;
// Verify we still have at least the Global resource locked.
invariant(_opCtx->lockState()->isLocked());
_opCtx->lockState()->lock(_opCtx, _id, _mode);
_result = LOCK_OK;
}
Lock::CollectionLock::CollectionLock(OperationContext* opCtx,
const NamespaceStringOrUUID& nssOrUUID,
LockMode mode,
Date_t deadline)
: _opCtx(opCtx) {
if (nssOrUUID.nss()) {
auto& nss = *nssOrUUID.nss();
_id = {RESOURCE_COLLECTION, nss.ns()};
invariant(nss.coll().size(), str::stream() << "expected non-empty collection name:" << nss);
dassert(_opCtx->lockState()->isDbLockedForMode(nss.db(),
isSharedLockMode(mode) ? MODE_IS : MODE_IX));
_opCtx->lockState()->lock(_opCtx, _id, mode, deadline);
return;
}
// 'nsOrUUID' must be a UUID and dbName.
auto nss = CollectionCatalog::get(opCtx)->resolveNamespaceStringOrUUID(opCtx, nssOrUUID);
// The UUID cannot move between databases so this one dassert is sufficient.
dassert(_opCtx->lockState()->isDbLockedForMode(nss.db(),
isSharedLockMode(mode) ? MODE_IS : MODE_IX));
// We cannot be sure that the namespace we lock matches the UUID given because we resolve the
// namespace from the UUID without the safety of a lock. Therefore, we will continue to re-lock
// until the namespace we resolve from the UUID before and after taking the lock is the same.
bool locked = false;
NamespaceString prevResolvedNss;
do {
if (locked) {
_opCtx->lockState()->unlock(_id);
}
_id = ResourceId(RESOURCE_COLLECTION, nss.ns());
_opCtx->lockState()->lock(_opCtx, _id, mode, deadline);
locked = true;
// We looked up UUID without a collection lock so it's possible that the
// collection name changed now. Look it up again.
prevResolvedNss = nss;
nss = CollectionCatalog::get(opCtx)->resolveNamespaceStringOrUUID(opCtx, nssOrUUID);
} while (nss != prevResolvedNss);
}
Lock::CollectionLock::CollectionLock(CollectionLock&& otherLock)
: _id(otherLock._id), _opCtx(otherLock._opCtx) {
otherLock._opCtx = nullptr;
}
Lock::CollectionLock::~CollectionLock() {
if (_opCtx)
_opCtx->lockState()->unlock(_id);
}
Lock::ParallelBatchWriterMode::ParallelBatchWriterMode(Locker* lockState)
: _pbwm(lockState, resourceIdParallelBatchWriterMode, MODE_X),
_shouldNotConflictBlock(lockState) {}
void Lock::ResourceLock::lock(OperationContext* opCtx, LockMode mode, Date_t deadline) {
invariant(_result == LOCK_INVALID);
_locker->lock(opCtx, _rid, mode, deadline);
_result = LOCK_OK;
}
void Lock::ResourceLock::unlock() {
if (_result == LOCK_OK) {
_locker->unlock(_rid);
_result = LOCK_INVALID;
}
}
} // namespace mongo
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