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shard_role.cpp
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shard_role.cpp
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/**
* Copyright (C) 2022-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.
*/
#include "mongo/db/shard_role.h"
#include <boost/utility/in_place_factory.hpp>
#include <exception>
#include <map>
#include "mongo/db/catalog/catalog_helper.h"
#include "mongo/db/catalog/collection_catalog.h"
#include "mongo/db/catalog/collection_uuid_mismatch.h"
#include "mongo/db/catalog/collection_uuid_mismatch_info.h"
#include "mongo/db/concurrency/exception_util.h"
#include "mongo/db/curop.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/repl/read_concern_args.h"
#include "mongo/db/s/collection_sharding_runtime.h"
#include "mongo/db/s/collection_sharding_state.h"
#include "mongo/db/s/database_sharding_state.h"
#include "mongo/db/s/operation_sharding_state.h"
#include "mongo/db/s/scoped_collection_metadata.h"
#include "mongo/db/storage/capped_snapshots.h"
#include "mongo/logv2/log.h"
#include "mongo/util/decorable.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kSharding
namespace mongo {
namespace {
auto getTransactionResources = OperationContext::declareDecoration<
std::unique_ptr<shard_role_details::TransactionResources>>();
shard_role_details::TransactionResources& getOrMakeTransactionResources(OperationContext* opCtx) {
auto& readConcern = repl::ReadConcernArgs::get(opCtx);
auto& optTransactionResources = getTransactionResources(opCtx);
if (!optTransactionResources) {
optTransactionResources =
std::make_unique<shard_role_details::TransactionResources>(readConcern);
}
return *optTransactionResources;
}
struct ResolvedNamespaceOrViewAcquisitionRequest {
// Populated in the first phase of collection(s) acquisition
AcquisitionPrerequisites prerequisites;
// Populated optionally in the second phase of collection(s) acquisition
std::shared_ptr<Lock::DBLock> dbLock;
boost::optional<Lock::CollectionLock> collLock;
};
using ResolvedNamespaceOrViewAcquisitionRequestsMap =
std::map<ResourceId, ResolvedNamespaceOrViewAcquisitionRequest>;
/**
* Takes the input acquisitions, populates the NSS and UUID parts and returns a list, sorted by NSS,
* suitable for a defined lock acquisition order.
*/
ResolvedNamespaceOrViewAcquisitionRequestsMap resolveNamespaceOrViewAcquisitionRequests(
OperationContext* opCtx,
const CollectionCatalog& catalog,
const std::vector<CollectionOrViewAcquisitionRequest>& acquisitionRequests) {
ResolvedNamespaceOrViewAcquisitionRequestsMap sortedAcquisitionRequests;
for (const auto& ar : acquisitionRequests) {
if (ar.nss) {
uassert(ErrorCodes::InvalidNamespace,
str::stream() << "Namespace " << ar.nss->toStringForErrorMsg()
<< "is not a valid collection name",
ar.nss->isValid());
auto coll = catalog.lookupCollectionByNamespace(opCtx, *ar.nss);
checkCollectionUUIDMismatch(opCtx, *ar.nss, coll, ar.uuid);
AcquisitionPrerequisites prerequisites(
*ar.nss, ar.uuid, ar.placementConcern, ar.operationType, ar.viewMode);
ResolvedNamespaceOrViewAcquisitionRequest resolvedAcquisitionRequest{
prerequisites, nullptr, boost::none};
sortedAcquisitionRequests.emplace(ResourceId(RESOURCE_COLLECTION, *ar.nss),
std::move(resolvedAcquisitionRequest));
} else if (ar.dbname) {
invariant(ar.uuid);
uassert(ErrorCodes::InvalidNamespace,
str::stream() << "Invalid db name " << ar.dbname->toStringForErrorMsg(),
NamespaceString::validDBName(*ar.dbname,
NamespaceString::DollarInDbNameBehavior::Allow));
auto coll = catalog.lookupCollectionByUUID(opCtx, *ar.uuid);
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "Namespace " << (*ar.dbname).toStringForErrorMsg() << ":"
<< *ar.uuid << " not found",
coll);
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "Database name mismatch for "
<< (*ar.dbname).toStringForErrorMsg() << ":" << *ar.uuid
<< ". Expected: " << (*ar.dbname).toStringForErrorMsg()
<< " Actual: " << coll->ns().dbName().toStringForErrorMsg(),
coll->ns().dbName() == *ar.dbname);
if (ar.nss) {
checkCollectionUUIDMismatch(opCtx, *ar.nss, coll, *ar.uuid);
}
AcquisitionPrerequisites prerequisites(
coll->ns(), coll->uuid(), ar.placementConcern, ar.operationType, ar.viewMode);
ResolvedNamespaceOrViewAcquisitionRequest resolvedAcquisitionRequest{
prerequisites, nullptr, boost::none};
sortedAcquisitionRequests.emplace(ResourceId(RESOURCE_COLLECTION, coll->ns()),
std::move(resolvedAcquisitionRequest));
} else {
MONGO_UNREACHABLE;
}
}
return sortedAcquisitionRequests;
}
void verifyDbAndCollection(OperationContext* opCtx,
const NamespaceString& nss,
CollectionPtr& coll,
AcquisitionPrerequisites::OperationType operationType) {
invariant(coll);
// In most cases we expect modifications for system.views to upgrade MODE_IX to MODE_X
// before taking the lock. One exception is a query by UUID of system.views in a
// transaction. Usual queries of system.views (by name, not UUID) within a transaction are
// rejected. However, if the query is by UUID we can't determine whether the namespace is
// actually system.views until we take the lock here. So we have this one last assertion.
uassert(6944500,
"Modifications to system.views must take an exclusive lock",
!nss.isSystemDotViews() || opCtx->lockState()->isCollectionLockedForMode(nss, MODE_X));
// Verify that we are using the latest instance if we intend to perform writes.
if (operationType == AcquisitionPrerequisites::OperationType::kWrite) {
auto latest = CollectionCatalog::latest(opCtx);
if (!latest->containsCollection(opCtx, coll.get())) {
throwWriteConflictException(str::stream() << "Unable to write to collection '"
<< coll->ns().toStringForErrorMsg()
<< "' due to catalog changes; please "
"retry the operation");
}
if (opCtx->recoveryUnit()->isActive()) {
const auto mySnapshot = opCtx->recoveryUnit()->getPointInTimeReadTimestamp(opCtx);
if (mySnapshot && *mySnapshot < coll->getMinimumValidSnapshot()) {
throwWriteConflictException(str::stream()
<< "Unable to write to collection '"
<< coll->ns().toStringForErrorMsg()
<< "' due to snapshot timestamp " << *mySnapshot
<< " being older than collection minimum "
<< *coll->getMinimumValidSnapshot()
<< "; please retry the operation");
}
}
}
}
void checkPlacementVersion(OperationContext* opCtx,
const NamespaceString& nss,
const PlacementConcern& placementConcern) {
const auto& receivedDbVersion = placementConcern.dbVersion;
if (receivedDbVersion) {
DatabaseShardingState::assertMatchingDbVersion(opCtx, nss.dbName(), *receivedDbVersion);
}
const auto& receivedShardVersion = placementConcern.shardVersion;
if (receivedShardVersion) {
const auto scopedCSS = CollectionShardingState::acquire(opCtx, nss);
scopedCSS->checkShardVersionOrThrow(opCtx, *receivedShardVersion);
}
}
std::variant<CollectionPtr, std::shared_ptr<const ViewDefinition>> acquireLocalCollectionOrView(
OperationContext* opCtx,
const CollectionCatalog& catalog,
const AcquisitionPrerequisites& prerequisites) {
const auto& nss = prerequisites.nss;
// TODO SERVER-76415 fix secondary reads if shouldReadAtLastApplied
auto readTimestamp = opCtx->recoveryUnit()->getPointInTimeReadTimestamp(opCtx);
auto coll = CollectionPtr(catalog.establishConsistentCollection(
opCtx, NamespaceStringOrUUID(prerequisites.nss), readTimestamp));
checkCollectionUUIDMismatch(opCtx, nss, coll, prerequisites.uuid);
if (coll) {
verifyDbAndCollection(opCtx, nss, coll, prerequisites.operationType);
return coll;
} else if (auto view = catalog.lookupView(opCtx, nss)) {
uassert(ErrorCodes::CommandNotSupportedOnView,
str::stream() << "Namespace " << nss.toStringForErrorMsg()
<< " is a view, not a collection",
prerequisites.viewMode == AcquisitionPrerequisites::kCanBeView);
return view;
} else {
return CollectionPtr();
}
}
struct SnapshotedServices {
std::variant<CollectionPtr, std::shared_ptr<const ViewDefinition>> collectionPtrOrView;
boost::optional<ScopedCollectionDescription> collectionDescription;
boost::optional<ScopedCollectionFilter> ownershipFilter;
};
SnapshotedServices acquireServicesSnapshot(OperationContext* opCtx,
const CollectionCatalog& catalog,
const AcquisitionPrerequisites& prerequisites) {
if (stdx::holds_alternative<AcquisitionPrerequisites::PlacementConcernPlaceholder>(
prerequisites.placementConcern)) {
return SnapshotedServices{
acquireLocalCollectionOrView(opCtx, catalog, prerequisites), boost::none, boost::none};
}
const auto& placementConcern = stdx::get<PlacementConcern>(prerequisites.placementConcern);
auto collOrView = acquireLocalCollectionOrView(opCtx, catalog, prerequisites);
const auto& nss = prerequisites.nss;
const bool isPlacementConcernVersioned =
placementConcern.dbVersion || placementConcern.shardVersion;
const auto scopedCSS = CollectionShardingState::acquire(opCtx, nss);
auto collectionDescription =
scopedCSS->getCollectionDescription(opCtx, isPlacementConcernVersioned);
invariant(!collectionDescription.isSharded() || placementConcern.shardVersion);
auto optOwnershipFilter = collectionDescription.isSharded()
? boost::optional<ScopedCollectionFilter>(scopedCSS->getOwnershipFilter(
opCtx,
prerequisites.operationType == AcquisitionPrerequisites::OperationType::kRead
? CollectionShardingState::OrphanCleanupPolicy::kDisallowOrphanCleanup
: CollectionShardingState::OrphanCleanupPolicy::kAllowOrphanCleanup,
*placementConcern.shardVersion))
: boost::none;
// TODO: This will be removed when we no longer snapshot sharding state on CollectionPtr.
if (std::holds_alternative<CollectionPtr>(collOrView) && collectionDescription.isSharded()) {
std::get<CollectionPtr>(collOrView)
.setShardKeyPattern(collectionDescription.getKeyPattern());
}
return SnapshotedServices{
std::move(collOrView), std::move(collectionDescription), std::move(optOwnershipFilter)};
}
std::vector<ScopedCollectionOrViewAcquisition> acquireResolvedCollectionsOrViewsWithoutTakingLocks(
OperationContext* opCtx,
const CollectionCatalog& catalog,
ResolvedNamespaceOrViewAcquisitionRequestsMap sortedAcquisitionRequests) {
std::vector<ScopedCollectionOrViewAcquisition> acquisitions;
for (auto& acquisitionRequest : sortedAcquisitionRequests) {
tassert(7328900,
"Cannot acquire for write without locks",
acquisitionRequest.second.prerequisites.operationType ==
AcquisitionPrerequisites::kRead ||
acquisitionRequest.second.collLock);
auto& prerequisites = acquisitionRequest.second.prerequisites;
auto snapshotedServices = acquireServicesSnapshot(opCtx, catalog, prerequisites);
const bool isCollection =
std::holds_alternative<CollectionPtr>(snapshotedServices.collectionPtrOrView);
if (isCollection) {
shard_role_details::AcquiredCollection& acquiredCollection =
getOrMakeTransactionResources(opCtx).addAcquiredCollection(
{prerequisites,
std::move(acquisitionRequest.second.dbLock),
std::move(acquisitionRequest.second.collLock),
std::move(snapshotedServices.collectionDescription),
std::move(snapshotedServices.ownershipFilter),
std::move(std::get<CollectionPtr>(snapshotedServices.collectionPtrOrView))});
ScopedCollectionAcquisition scopedAcquisition(opCtx, acquiredCollection);
acquisitions.emplace_back(std::move(scopedAcquisition));
} else {
// It's a view.
const shard_role_details::AcquiredView& acquiredView =
getOrMakeTransactionResources(opCtx).addAcquiredView(
{prerequisites,
std::move(acquisitionRequest.second.dbLock),
std::move(acquisitionRequest.second.collLock),
std::move(std::get<std::shared_ptr<const ViewDefinition>>(
snapshotedServices.collectionPtrOrView))});
ScopedViewAcquisition scopedAcquisition(opCtx, acquiredView);
acquisitions.emplace_back(std::move(scopedAcquisition));
}
}
return acquisitions;
}
/*
* Establish a capped snapshot if necessary on the provided namespace.
*/
void establishCappedSnapshotIfNeeded(OperationContext* opCtx,
const std::shared_ptr<const CollectionCatalog>& catalog,
const NamespaceStringOrUUID& nsOrUUID) {
auto coll = catalog->lookupCollectionByNamespaceOrUUID(opCtx, nsOrUUID);
if (coll && coll->usesCappedSnapshots()) {
CappedSnapshots::get(opCtx).establish(opCtx, coll);
}
}
bool haveAcquiredConsistentCatalogAndSnapshot(const CollectionCatalog* catalogBeforeSnapshot,
const CollectionCatalog* catalogAfterSnapshot,
long long replTermBeforeSnapshot,
long long replTermAfterSnapshot) {
return catalogBeforeSnapshot == catalogAfterSnapshot &&
replTermBeforeSnapshot == replTermAfterSnapshot;
}
std::shared_ptr<const CollectionCatalog> getConsistentCatalogAndSnapshot(
OperationContext* opCtx, const std::vector<NamespaceStringOrUUID>& acquisitionRequests) {
while (true) {
shard_role_details::SnapshotAttempt snapshotAttempt(opCtx, acquisitionRequests);
snapshotAttempt.snapshotInitialState();
snapshotAttempt.openStorageSnapshot();
if (auto catalog = snapshotAttempt.getConsistentCatalog()) {
return catalog;
}
}
}
std::vector<NamespaceStringOrUUID> toNamespaceStringOrUUIDs(
const std::list<shard_role_details::AcquiredCollection>& acquiredCollections) {
std::vector<NamespaceStringOrUUID> requests;
for (const auto& acquiredCollection : acquiredCollections) {
const auto& prerequisites = acquiredCollection.prerequisites;
requests.emplace_back(prerequisites.nss);
}
return requests;
}
std::vector<NamespaceStringOrUUID> toNamespaceStringOrUUIDs(
const std::vector<CollectionOrViewAcquisitionRequest>& acquisitionRequests) {
std::vector<NamespaceStringOrUUID> requests;
for (const auto& ar : acquisitionRequests) {
if (ar.nss) {
requests.emplace_back(*ar.nss);
} else {
requests.emplace_back(*ar.dbname, *ar.uuid);
}
}
return requests;
}
void checkShardingPlacement(
OperationContext* opCtx,
const std::vector<CollectionOrViewAcquisitionRequest>& acquisitionRequests) {
for (const auto& ar : acquisitionRequests) {
// We only have to check placement for collections that come from a router, which
// will have the namespace set.
if (ar.nss) {
checkPlacementVersion(opCtx, *ar.nss, ar.placementConcern);
}
}
}
std::shared_ptr<const CollectionCatalog> stashConsistentCatalog(
OperationContext* opCtx,
const std::vector<CollectionOrViewAcquisitionRequest>& acquisitionRequests) {
auto requests = toNamespaceStringOrUUIDs(acquisitionRequests);
auto catalog = getConsistentCatalogAndSnapshot(opCtx, requests);
// Stash the catalog, it will be automatically unstashed when the snapshot is released.
CollectionCatalog::stash(opCtx, catalog);
return catalog;
}
} // namespace
CollectionOrViewAcquisitionRequest CollectionOrViewAcquisitionRequest::fromOpCtx(
OperationContext* opCtx,
NamespaceString nss,
AcquisitionPrerequisites::OperationType operationType,
AcquisitionPrerequisites::ViewMode viewMode,
boost::optional<UUID> expectedUUID) {
auto& oss = OperationShardingState::get(opCtx);
auto& readConcern = repl::ReadConcernArgs::get(opCtx);
return CollectionOrViewAcquisitionRequest(
nss,
expectedUUID,
{oss.getDbVersion(nss.db()), oss.getShardVersion(nss)},
readConcern,
operationType,
viewMode);
}
CollectionAcquisitionRequest CollectionAcquisitionRequest::fromOpCtx(
OperationContext* opCtx,
NamespaceString nss,
AcquisitionPrerequisites::OperationType operationType,
boost::optional<UUID> expectedUUID) {
auto& oss = OperationShardingState::get(opCtx);
auto& readConcern = repl::ReadConcernArgs::get(opCtx);
return CollectionAcquisitionRequest(nss,
expectedUUID,
{oss.getDbVersion(nss.db()), oss.getShardVersion(nss)},
readConcern,
operationType);
}
CollectionAcquisitionRequest CollectionAcquisitionRequest::fromOpCtx(
OperationContext* opCtx,
NamespaceStringOrUUID nssOrUUID,
AcquisitionPrerequisites::OperationType operationType) {
auto& oss = OperationShardingState::get(opCtx);
auto& readConcern = repl::ReadConcernArgs::get(opCtx);
// Acquisitions by uuid cannot possibly have a corresponding ShardVersion attached.
PlacementConcern placementConcern = nssOrUUID.nss()
? PlacementConcern{oss.getDbVersion(nssOrUUID.dbName().db()),
oss.getShardVersion(*nssOrUUID.nss())}
: PlacementConcern{oss.getDbVersion(nssOrUUID.dbName().db()), {}};
return CollectionAcquisitionRequest(nssOrUUID, placementConcern, readConcern, operationType);
}
UUID ScopedCollectionAcquisition::uuid() const {
invariant(exists(),
str::stream() << "Collection " << nss().toStringForErrorMsg()
<< " doesn't exist, so its UUID cannot be obtained");
return _acquiredCollection.collectionPtr->uuid();
}
const ScopedCollectionDescription& ScopedCollectionAcquisition::getShardingDescription() const {
// The collectionDescription will only not be set if the caller as acquired the acquisition
// using the kLocalCatalogOnlyWithPotentialDataLoss placement concern
invariant(_acquiredCollection.collectionDescription);
return *_acquiredCollection.collectionDescription;
}
const boost::optional<ScopedCollectionFilter>& ScopedCollectionAcquisition::getShardingFilter()
const {
// The collectionDescription will only not be set if the caller as acquired the acquisition
// using the kLocalCatalogOnlyWithPotentialDataLoss placement concern
invariant(_acquiredCollection.collectionDescription);
return _acquiredCollection.ownershipFilter;
}
const CollectionPtr& ScopedCollectionAcquisition::getCollectionPtr() const {
tassert(ErrorCodes::InternalError,
"Collection acquisition has been invalidated",
!_acquiredCollection.invalidated);
return _acquiredCollection.collectionPtr;
}
ScopedCollectionAcquisition::~ScopedCollectionAcquisition() {
if (_opCtx) {
const auto& transactionResources = getTransactionResources(_opCtx);
if (transactionResources) {
transactionResources->acquiredCollections.remove_if(
[this](const shard_role_details::AcquiredCollection& txnResourceAcquiredColl) {
return &txnResourceAcquiredColl == &(this->_acquiredCollection);
});
if (transactionResources->acquiredCollections.empty() &&
transactionResources->acquiredViews.empty()) {
transactionResources->releaseAllResourcesOnCommitOrAbort();
}
}
}
}
ScopedViewAcquisition::~ScopedViewAcquisition() {
if (_opCtx) {
const auto& transactionResources = getTransactionResources(_opCtx);
if (transactionResources) {
transactionResources->acquiredViews.remove_if(
[this](const shard_role_details::AcquiredView& txnResourceAcquiredView) {
return &txnResourceAcquiredView == &(this->_acquiredView);
});
if (transactionResources->acquiredCollections.empty() &&
transactionResources->acquiredViews.empty()) {
transactionResources->releaseAllResourcesOnCommitOrAbort();
}
}
}
}
ScopedCollectionAcquisition acquireCollection(OperationContext* opCtx,
CollectionAcquisitionRequest acquisitionRequest,
LockMode mode) {
return std::get<ScopedCollectionAcquisition>(
acquireCollectionOrView(opCtx, acquisitionRequest, mode));
}
std::vector<ScopedCollectionAcquisition> acquireCollections(
OperationContext* opCtx,
std::vector<CollectionAcquisitionRequest> acquisitionRequests,
LockMode mode) {
// Transform the CollectionAcquisitionRequests to NamespaceOrViewAcquisitionRequests.
std::vector<CollectionOrViewAcquisitionRequest> namespaceOrViewAcquisitionRequests;
std::move(acquisitionRequests.begin(),
acquisitionRequests.end(),
std::back_inserter(namespaceOrViewAcquisitionRequests));
// Acquire the collections
auto acquisitions = acquireCollectionsOrViews(opCtx, namespaceOrViewAcquisitionRequests, mode);
// Transform the acquisitions to ScopedCollectionAcquisitions
std::vector<ScopedCollectionAcquisition> collectionAcquisitions;
for (auto& acquisition : acquisitions) {
// It must be a collection, because that's what the acquisition request stated.
invariant(std::holds_alternative<ScopedCollectionAcquisition>(acquisition));
collectionAcquisitions.emplace_back(
std::move(std::get<ScopedCollectionAcquisition>(acquisition)));
}
return collectionAcquisitions;
}
ScopedCollectionOrViewAcquisition acquireCollectionOrView(
OperationContext* opCtx, CollectionOrViewAcquisitionRequest acquisitionRequest, LockMode mode) {
auto acquisition = acquireCollectionsOrViews(opCtx, {std::move(acquisitionRequest)}, mode);
invariant(acquisition.size() == 1);
return std::move(acquisition.front());
}
namespace shard_role_details {
void SnapshotAttempt::snapshotInitialState() {
// The read source used can change depending on replication state, so we must fetch the repl
// state beforehand, to compare with afterwards.
_replTermBeforeSnapshot = repl::ReplicationCoordinator::get(_opCtx)->getTerm();
_catalogBeforeSnapshot = CollectionCatalog::get(_opCtx);
}
void SnapshotAttempt::openStorageSnapshot() {
invariant(_catalogBeforeSnapshot && _replTermBeforeSnapshot);
if (_opCtx->recoveryUnit()->isActive()) {
// We already have an open storage snapshot, nothing to do.
return;
}
for (auto& nssOrUUID : _acquisitionRequests) {
establishCappedSnapshotIfNeeded(_opCtx, *_catalogBeforeSnapshot, nssOrUUID);
}
// TODO SERVER-76415 call preallocateSnapshotForOplogRead() when reading from the oplog.
_opCtx->recoveryUnit()->preallocateSnapshot();
_openedSnapshot = true;
}
std::shared_ptr<const CollectionCatalog> SnapshotAttempt::getConsistentCatalog() {
invariant(_catalogBeforeSnapshot && _replTermBeforeSnapshot &&
_opCtx->recoveryUnit()->isActive());
auto catalogAfterSnapshot = CollectionCatalog::get(_opCtx);
const auto replTermAfterSnapshot = repl::ReplicationCoordinator::get(_opCtx)->getTerm();
if (!haveAcquiredConsistentCatalogAndSnapshot(_catalogBeforeSnapshot->get(),
catalogAfterSnapshot.get(),
*_replTermBeforeSnapshot,
replTermAfterSnapshot)) {
return nullptr;
}
_successful = true;
return catalogAfterSnapshot;
}
SnapshotAttempt::~SnapshotAttempt() {
if (_successful) {
// We were successful, nothing to clean up.
return;
}
// We can't abandon the snapshot if we are in a WUOW.
if (_openedSnapshot && !_opCtx->lockState()->inAWriteUnitOfWork()) {
_opCtx->recoveryUnit()->abandonSnapshot();
}
CurOp::get(_opCtx)->yielded();
}
ResolvedNamespaceOrViewAcquisitionRequestsMap generateSortedAcquisitionRequests(
OperationContext* opCtx,
const CollectionCatalog& catalog,
const std::vector<CollectionOrViewAcquisitionRequest>& acquisitionRequests) {
ResolvedNamespaceOrViewAcquisitionRequestsMap sortedAcquisitionRequests;
auto readTimestamp = opCtx->recoveryUnit()->getPointInTimeReadTimestamp(opCtx);
int counter = 0;
for (const auto& ar : acquisitionRequests) {
NamespaceStringOrUUID nssOrUUID =
ar.nss ? NamespaceStringOrUUID(*ar.nss) : NamespaceStringOrUUID(*ar.dbname, *ar.uuid);
uassertStatusOK(nssOrUUID.isNssValid());
uassert(ErrorCodes::InvalidNamespace,
str::stream() << "Invalid db name " << ar.dbname->toStringForErrorMsg(),
NamespaceString::validDBName(nssOrUUID.dbName(),
NamespaceString::DollarInDbNameBehavior::Allow));
auto coll =
CollectionPtr(catalog.establishConsistentCollection(opCtx, nssOrUUID, readTimestamp));
// If we are acquiring by UUID and no collection matches, raise NamespaceNotFound.
if (!ar.nss) {
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "Namespace " << (*ar.dbname).toStringForErrorMsg() << ":"
<< *ar.uuid << " not found",
coll);
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "Database name mismatch for "
<< (*ar.dbname).toStringForErrorMsg() << ":" << *ar.uuid
<< ". Expected: " << (*ar.dbname).toStringForErrorMsg()
<< " Actual: " << coll->ns().dbName().toStringForErrorMsg(),
coll->ns().dbName() == *ar.dbname);
}
const auto& nss = ar.nss ? *ar.nss : coll->ns();
AcquisitionPrerequisites prerequisites(
nss, ar.uuid, ar.placementConcern, ar.operationType, ar.viewMode);
ResolvedNamespaceOrViewAcquisitionRequest resolvedAcquisitionRequest{
prerequisites, nullptr, boost::none};
// We don't care about ordering in this case, use a mock ResourceId as the key.
sortedAcquisitionRequests.emplace(ResourceId(RESOURCE_COLLECTION, counter++),
std::move(resolvedAcquisitionRequest));
}
return sortedAcquisitionRequests;
}
} // namespace shard_role_details
std::vector<ScopedCollectionOrViewAcquisition> acquireCollectionsOrViews(
OperationContext* opCtx,
std::vector<CollectionOrViewAcquisitionRequest> acquisitionRequests,
LockMode mode) {
if (acquisitionRequests.size() == 0) {
return {};
}
// We shouldn't have an open snapshot unless we are in a multi document transaction or a
// previous acquisition opened and stashed it already.
// TODO enable invariant when everything uses acquisitions.
bool inMultiDocumentTransaction = opCtx->inMultiDocumentTransaction();
while (true) {
// Optimistically populate the nss and uuid parts of the resolved acquisition requests and
// sort them
auto sortedAcquisitionRequests = resolveNamespaceOrViewAcquisitionRequests(
opCtx, *CollectionCatalog::get(opCtx), acquisitionRequests);
// At this point, sortedAcquisitionRequests contains fully resolved (both nss and uuid)
// namespace or view requests in sorted order. However, there is still no guarantee that the
// nss <-> uuid mapping won't change from underneath.
//
// Lock the collection locks in the sorted order and recheck the UUIDS. If it throws
// CollectionUUIDMismatch, we need to start over.
const auto& dbName = sortedAcquisitionRequests.begin()->second.prerequisites.nss.dbName();
Lock::DBLockSkipOptions dbLockOptions = [&]() {
Lock::DBLockSkipOptions dbLockOptions;
dbLockOptions.skipRSTLLock =
std::all_of(sortedAcquisitionRequests.begin(),
sortedAcquisitionRequests.end(),
[](const auto& ar) {
return AutoGetDb::canSkipRSTLLock(ar.second.prerequisites.nss);
});
dbLockOptions.skipFlowControlTicket = std::all_of(
sortedAcquisitionRequests.begin(),
sortedAcquisitionRequests.end(),
[](const auto& ar) {
return AutoGetDb::canSkipFlowControlTicket(ar.second.prerequisites.nss);
});
return dbLockOptions;
}();
const auto dbLock =
std::make_shared<Lock::DBLock>(opCtx,
dbName,
isSharedLockMode(mode) ? MODE_IS : MODE_IX,
Date_t::max(),
dbLockOptions);
for (auto& ar : sortedAcquisitionRequests) {
const auto& nss = ar.second.prerequisites.nss;
tassert(7300400,
str::stream()
<< "Cannot acquire locks for collections across different databases ('"
<< dbName.toStringForErrorMsg() << "' vs '"
<< nss.dbName().toStringForErrorMsg() << "'",
dbName == nss.dbName());
ar.second.dbLock = dbLock;
ar.second.collLock.emplace(opCtx, nss, mode);
}
// Wait for a configured amount of time after acquiring locks if the failpoint is
// enabled
catalog_helper::setAutoGetCollectionWaitFailpointExecute([&](const BSONObj& data) {
sleepFor(Milliseconds(data["waitForMillis"].numberInt()));
});
// Recheck UUIDs. For writes in multi document transactions we need to use the latest
// catalog and throw a WW conflict if UUIDs don't match. In all other cases we use the
// current catalog and retry the loop.
const auto& currentCatalog = CollectionCatalog::get(opCtx);
const auto& latestCatalog = CollectionCatalog::latest(opCtx);
for (auto& ar : sortedAcquisitionRequests) {
const auto& prerequisites = ar.second.prerequisites;
auto changedUUID = [&](auto& catalog) {
const auto coll = catalog->lookupCollectionByNamespace(opCtx, prerequisites.nss);
if (prerequisites.uuid && (!coll || coll->uuid() != prerequisites.uuid)) {
return true;
}
return false;
};
bool writeInMultiDocumentTransaction = inMultiDocumentTransaction &&
prerequisites.operationType == AcquisitionPrerequisites::OperationType::kWrite;
if (changedUUID(writeInMultiDocumentTransaction ? latestCatalog : currentCatalog)) {
if (writeInMultiDocumentTransaction) {
throwWriteConflictException(
str::stream() << "Unable to write to collection '" << prerequisites.nss
<< "' due to catalog changes; please retry the operation");
} else {
// Retry optimistic resolution.
continue;
}
}
}
checkShardingPlacement(opCtx, acquisitionRequests);
// TODO SERVER-76901 open consistent storage snapshot.
auto catalog = CollectionCatalog::get(opCtx);
return acquireResolvedCollectionsOrViewsWithoutTakingLocks(
opCtx, *catalog, std::move(sortedAcquisitionRequests));
}
}
std::vector<ScopedCollectionOrViewAcquisition> acquireCollectionsOrViewsWithoutTakingLocks(
OperationContext* opCtx, std::vector<CollectionOrViewAcquisitionRequest> acquisitionRequests) {
if (acquisitionRequests.size() == 0) {
return {};
}
// We shouldn't have an open snapshot unless a previous lock-free acquisition opened and stashed
// it already.
invariant(!opCtx->recoveryUnit()->isActive() || opCtx->isLockFreeReadsOp());
// TODO SERVER-76415 take global lock.
// Make sure the sharding placement is correct before opening the storage snapshot, we will
// check it again after opening it to make sure it is consistent. This is specially important in
// secondaries since they can be lagging and might not be aware of the latests routing changes.
checkShardingPlacement(opCtx, acquisitionRequests);
// Open a consistent catalog snapshot if needed.
bool openSnapshot = !opCtx->recoveryUnit()->isActive();
auto catalog = openSnapshot ? stashConsistentCatalog(opCtx, acquisitionRequests)
: CollectionCatalog::get(opCtx);
try {
// Second sharding placement check.
checkShardingPlacement(opCtx, acquisitionRequests);
auto sortedAcquisitionRequests = shard_role_details::generateSortedAcquisitionRequests(
opCtx, *catalog, acquisitionRequests);
return acquireResolvedCollectionsOrViewsWithoutTakingLocks(
opCtx, *catalog, std::move(sortedAcquisitionRequests));
} catch (...) {
if (openSnapshot && !opCtx->lockState()->inAWriteUnitOfWork())
opCtx->recoveryUnit()->abandonSnapshot();
throw;
}
}
ScopedCollectionAcquisition acquireCollectionForLocalCatalogOnlyWithPotentialDataLoss(
OperationContext* opCtx, const NamespaceString& nss, LockMode mode) {
invariant(!OperationShardingState::isComingFromRouter(opCtx));
auto& txnResources = getOrMakeTransactionResources(opCtx);
txnResources.assertNoAcquiredCollections();
auto dbLock = std::make_shared<Lock::DBLock>(
opCtx, nss.dbName(), isSharedLockMode(mode) ? MODE_IS : MODE_IX);
Lock::CollectionLock collLock(opCtx, nss, mode);
const auto catalog = CollectionCatalog::get(opCtx);
auto prerequisites =
AcquisitionPrerequisites(nss,
boost::none,
AcquisitionPrerequisites::kLocalCatalogOnlyWithPotentialDataLoss,
AcquisitionPrerequisites::OperationType::kWrite,
AcquisitionPrerequisites::ViewMode::kMustBeCollection);
auto collOrView = acquireLocalCollectionOrView(opCtx, *catalog, prerequisites);
invariant(std::holds_alternative<CollectionPtr>(collOrView));
auto& coll = std::get<CollectionPtr>(collOrView);
shard_role_details::AcquiredCollection& acquiredCollection = txnResources.addAcquiredCollection(
{AcquisitionPrerequisites(nss,
coll ? boost::optional<UUID>(coll->uuid()) : boost::none,
AcquisitionPrerequisites::kLocalCatalogOnlyWithPotentialDataLoss,
AcquisitionPrerequisites::OperationType::kWrite,
AcquisitionPrerequisites::ViewMode::kMustBeCollection),
std::move(dbLock),
std::move(collLock),
boost::none,
boost::none,
std::move(coll)});
return ScopedCollectionAcquisition(opCtx, acquiredCollection);
}
ScopedLocalCatalogWriteFence::ScopedLocalCatalogWriteFence(OperationContext* opCtx,
ScopedCollectionAcquisition* acquisition)
: _opCtx(opCtx), _acquiredCollection(&acquisition->_acquiredCollection) {
// Clear the collectionPtr from the acquisition to indicate that it should not be used until the
// caller is done with the DDL modifications
_acquiredCollection->collectionPtr = CollectionPtr();
// OnCommit, there is nothing to do because the caller is not allowed to use the collection in
// the scope of the ScopedLocalCatalogWriteFence and the destructor will take care of updating
// the acquisition to point to the latest changed value.
std::weak_ptr<shard_role_details::AcquiredCollection::SharedImpl> sharedImplWeakPtr =
_acquiredCollection->sharedImpl;
opCtx->recoveryUnit()->onRollback(
[acquiredCollection = _acquiredCollection,
sharedImplWeakPtr = sharedImplWeakPtr](OperationContext* opCtx) mutable {
// OnRollback, the acquired collection must be set to reference the previously
// established catalog snapshot
if (!sharedImplWeakPtr.expired()) {
_updateAcquiredLocalCollection(opCtx, acquiredCollection);
}
});
}
ScopedLocalCatalogWriteFence::~ScopedLocalCatalogWriteFence() {
_updateAcquiredLocalCollection(_opCtx, _acquiredCollection);
}
void ScopedLocalCatalogWriteFence::_updateAcquiredLocalCollection(
OperationContext* opCtx, shard_role_details::AcquiredCollection* acquiredCollection) {
try {
const auto catalog = CollectionCatalog::latest(opCtx);
const auto& nss = acquiredCollection->prerequisites.nss;
auto collection =
catalog->lookupCollectionByNamespace(opCtx, acquiredCollection->prerequisites.nss);
checkCollectionUUIDMismatch(opCtx, nss, collection, acquiredCollection->prerequisites.uuid);
acquiredCollection->collectionPtr = CollectionPtr(collection);
} catch (const DBException& ex) {
LOGV2_DEBUG(7653800,
1,
"Failed to update ScopedLocalCatalogWriteFence",
"ex"_attr = redact(ex.toString()));
acquiredCollection->invalidated = true;
}
}
YieldedTransactionResources::~YieldedTransactionResources() {
invariant(!_yieldedResources);
}
YieldedTransactionResources::YieldedTransactionResources(
std::unique_ptr<shard_role_details::TransactionResources>&& yieldedResources)
: _yieldedResources(std::move(yieldedResources)) {}
void YieldedTransactionResources::dispose() {
if (_yieldedResources) {
_yieldedResources->releaseAllResourcesOnCommitOrAbort();
_yieldedResources.reset();
}
}
boost::optional<YieldedTransactionResources> yieldTransactionResourcesFromOperationContext(
OperationContext* opCtx) {
auto& transactionResources = getTransactionResources(opCtx);
if (!transactionResources) {
return YieldedTransactionResources();
}
invariant(!transactionResources->yielded);
for (auto& acquisition : transactionResources->acquiredCollections) {
// Yielding kLocalCatalogOnlyWithPotentialDataLoss acquisitions is not allowed.
invariant(
!stdx::holds_alternative<AcquisitionPrerequisites::PlacementConcernPlaceholder>(
acquisition.prerequisites.placementConcern),
str::stream() << "Collection " << acquisition.prerequisites.nss.toStringForErrorMsg()
<< " acquired with special placement concern and cannot be yielded");
// If the uuid wasn't originally set on the prerequisites, set it now so that on restore
// from yield we can check we are restoring the same instance of the ns.
if (!acquisition.prerequisites.uuid && acquisition.collectionPtr) {
acquisition.prerequisites.uuid = acquisition.collectionPtr->uuid();
}
}
// Yielding view acquisitions is not supported.
tassert(7300502,
"Yielding view acquisitions is forbidden",
transactionResources->acquiredViews.empty());
invariant(!transactionResources->lockSnapshot);
Locker::LockSnapshot lockSnapshot;
opCtx->lockState()->saveLockStateAndUnlock(&lockSnapshot);
transactionResources->lockSnapshot.emplace(std::move(lockSnapshot));
transactionResources->yielded = true;
return YieldedTransactionResources(std::move(transactionResources));
}
void restoreTransactionResourcesToOperationContext(OperationContext* opCtx,
YieldedTransactionResources&& yieldedResources) {
if (!yieldedResources._yieldedResources) {
// Nothing to restore.
return;
}
// On failure to restore, release the yielded resources.
ScopeGuard scopeGuard([&] {
yieldedResources._yieldedResources->releaseAllResourcesOnCommitOrAbort();
yieldedResources._yieldedResources.reset();
});
auto restoreFn = [&]() {
// Reacquire locks.
if (yieldedResources._yieldedResources->lockSnapshot) {
opCtx->lockState()->restoreLockState(opCtx,
*yieldedResources._yieldedResources->lockSnapshot);
yieldedResources._yieldedResources->lockSnapshot.reset();
}
// Reestablish a consistent catalog snapshot (multi document transactions don't yield).
auto requests =
toNamespaceStringOrUUIDs(yieldedResources._yieldedResources->acquiredCollections);
auto catalog = getConsistentCatalogAndSnapshot(opCtx, requests);
// Reacquire service snapshots. Will throw if placement concern can no longer be met.
for (auto& acquiredCollection : yieldedResources._yieldedResources->acquiredCollections) {
const auto& prerequisites = acquiredCollection.prerequisites;
auto uassertCollectionAppearedAfterRestore = [&] {
uasserted(
743870,
str::stream()
<< "Collection " << prerequisites.nss.toStringForErrorMsg()
<< " appeared after a restore, which violates the semantics of restore");
};
if (prerequisites.operationType == AcquisitionPrerequisites::OperationType::kRead) {
// Just reacquire the CollectionPtr. Reads don't care about placement changes
// because they have already established a ScopedCollectionFilter that acts as
// RangePreserver.
auto collOrView = acquireLocalCollectionOrView(opCtx, *catalog, prerequisites);
// We do not support yielding view acquisitions. Therefore it is not possible that
// upon restore 'acquireLocalCollectionOrView' snapshoted a view -- it would not
// have met the prerequisite that the collection instance is still the same as the
// one before yielding.
invariant(std::holds_alternative<CollectionPtr>(collOrView));
if (!acquiredCollection.collectionPtr != !std::get<CollectionPtr>(collOrView)) {
uassertCollectionAppearedAfterRestore();
}
// Update the services snapshot on TransactionResources
acquiredCollection.collectionPtr = std::move(std::get<CollectionPtr>(collOrView));
} else {
auto reacquiredServicesSnapshot =
acquireServicesSnapshot(opCtx, *catalog, prerequisites);
// We do not support yielding view acquisitions. Therefore it is not possible that
// upon restore 'acquireLocalCollectionOrView' snapshoted a view -- it would not
// have met the prerequisite that the collection instance is still the same as the
// one before yielding.