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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_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kReplication
#include "mongo/db/repl/oplog_applier_impl.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/collection_catalog.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/catalog/document_validation.h"
#include "mongo/db/catalog_raii.h"
#include "mongo/db/client.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/logical_session_id.h"
#include "mongo/db/repl/apply_ops.h"
#include "mongo/db/repl/insert_group.h"
#include "mongo/db/repl/transaction_oplog_application.h"
#include "mongo/db/stats/timer_stats.h"
#include "mongo/platform/basic.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/log.h"
#include "third_party/murmurhash3/MurmurHash3.h"
namespace mongo {
namespace repl {
namespace {
MONGO_FAIL_POINT_DEFINE(pauseBatchApplicationBeforeCompletion);
MONGO_FAIL_POINT_DEFINE(pauseBatchApplicationAfterWritingOplogEntries);
MONGO_FAIL_POINT_DEFINE(hangAfterRecordingOpApplicationStartTime);
// The oplog entries applied
Counter64 opsAppliedStats;
ServerStatusMetricField<Counter64> displayOpsApplied("repl.apply.ops", &opsAppliedStats);
// Tracks the oplog application batch size.
Counter64 oplogApplicationBatchSize;
ServerStatusMetricField<Counter64> displayOplogApplicationBatchSize("repl.apply.batchSize",
&oplogApplicationBatchSize);
// Number and time of each ApplyOps worker pool round
TimerStats applyBatchStats;
ServerStatusMetricField<TimerStats> displayOpBatchesApplied("repl.apply.batches", &applyBatchStats);
NamespaceString parseUUIDOrNs(OperationContext* opCtx, const OplogEntry& oplogEntry) {
auto optionalUuid = oplogEntry.getUuid();
if (!optionalUuid) {
return oplogEntry.getNss();
}
const auto& uuid = optionalUuid.get();
auto& catalog = CollectionCatalog::get(opCtx);
auto nss = catalog.lookupNSSByUUID(opCtx, uuid);
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "No namespace with UUID " << uuid.toString(),
nss);
return *nss;
}
NamespaceStringOrUUID getNsOrUUID(const NamespaceString& nss, const OplogEntry& op) {
if (auto ui = op.getUuid()) {
return {nss.db().toString(), ui.get()};
}
return nss;
}
/**
* Used for logging a report of ops that take longer than "slowMS" to apply. This is called
* right before returning from applyOplogEntryOrGroupedInserts, and it returns the same status.
*/
Status finishAndLogApply(ClockSource* clockSource,
Status finalStatus,
Date_t applyStartTime,
const OplogEntryOrGroupedInserts& entryOrGroupedInserts) {
if (finalStatus.isOK()) {
auto applyEndTime = clockSource->now();
auto diffMS = durationCount<Milliseconds>(applyEndTime - applyStartTime);
// This op was slow to apply, so we should log a report of it.
if (diffMS > serverGlobalParams.slowMS) {
StringBuilder s;
s << "applied op: ";
if (entryOrGroupedInserts.getOp().getOpType() == OpTypeEnum::kCommand) {
s << "command ";
} else {
s << "CRUD ";
}
s << redact(entryOrGroupedInserts.toBSON());
s << ", took " << diffMS << "ms";
log() << s.str();
}
}
return finalStatus;
}
LockMode fixLockModeForSystemDotViewsChanges(const NamespaceString& nss, LockMode mode) {
return nss.isSystemDotViews() ? MODE_X : mode;
}
/**
* Caches per-collection properties which are relevant for oplog application, so that they don't
* have to be retrieved repeatedly for each op.
*/
class CachedCollectionProperties {
public:
struct CollectionProperties {
bool isCapped = false;
const CollatorInterface* collator = nullptr;
};
CollectionProperties getCollectionProperties(OperationContext* opCtx,
const StringMapHashedKey& ns) {
auto it = _cache.find(ns);
if (it != _cache.end()) {
return it->second;
}
auto collProperties = getCollectionPropertiesImpl(opCtx, NamespaceString(ns.key()));
_cache[ns] = collProperties;
return collProperties;
}
private:
CollectionProperties getCollectionPropertiesImpl(OperationContext* opCtx,
const NamespaceString& nss) {
CollectionProperties collProperties;
auto collection = CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, nss);
if (!collection) {
return collProperties;
}
collProperties.isCapped = collection->isCapped();
collProperties.collator = collection->getDefaultCollator();
return collProperties;
}
StringMap<CollectionProperties> _cache;
};
/**
* Updates a CRUD op's hash and isForCappedCollection field if necessary.
*/
void processCrudOp(OperationContext* opCtx,
OplogEntry* op,
uint32_t* hash,
StringMapHashedKey* hashedNs,
CachedCollectionProperties* collPropertiesCache) {
const bool supportsDocLocking =
opCtx->getServiceContext()->getStorageEngine()->supportsDocLocking();
auto collProperties = collPropertiesCache->getCollectionProperties(opCtx, *hashedNs);
// For doc locking engines, include the _id of the document in the hash so we get
// parallelism even if all writes are to a single collection.
//
// For capped collections, this is illegal, since capped collections must preserve
// insertion order.
if (supportsDocLocking && !collProperties.isCapped) {
BSONElement id = op->getIdElement();
BSONElementComparator elementHasher(BSONElementComparator::FieldNamesMode::kIgnore,
collProperties.collator);
const size_t idHash = elementHasher.hash(id);
MurmurHash3_x86_32(&idHash, sizeof(idHash), *hash, hash);
}
if (op->getOpType() == OpTypeEnum::kInsert && collProperties.isCapped) {
// Mark capped collection ops before storing them to ensure we do not attempt to
// bulk insert them.
op->isForCappedCollection = true;
}
}
/**
* Adds a single oplog entry to the appropriate writer vector.
*/
void addToWriterVector(OplogEntry* op,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
uint32_t hash) {
const uint32_t numWriters = writerVectors->size();
auto& writer = (*writerVectors)[hash % numWriters];
if (writer.empty()) {
writer.reserve(8); // Skip a few growth rounds
}
writer.push_back(op);
}
/**
* Adds a set of derivedOps to writerVectors.
*/
void addDerivedOps(OperationContext* opCtx,
std::vector<OplogEntry>* derivedOps,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
CachedCollectionProperties* collPropertiesCache) {
for (auto&& op : *derivedOps) {
auto hashedNs = StringMapHasher().hashed_key(op.getNss().ns());
uint32_t hash = static_cast<uint32_t>(hashedNs.hash());
if (op.isCrudOpType()) {
processCrudOp(opCtx, &op, &hash, &hashedNs, collPropertiesCache);
}
addToWriterVector(&op, writerVectors, hash);
}
}
void stableSortByNamespace(std::vector<const OplogEntry*>* oplogEntryPointers) {
auto nssComparator = [](const OplogEntry* l, const OplogEntry* r) {
return l->getNss() < r->getNss();
};
std::stable_sort(oplogEntryPointers->begin(), oplogEntryPointers->end(), nssComparator);
}
} // namespace
namespace {
class ApplyBatchFinalizer {
public:
ApplyBatchFinalizer(ReplicationCoordinator* replCoord) : _replCoord(replCoord) {}
virtual ~ApplyBatchFinalizer(){};
virtual void record(const OpTimeAndWallTime& newOpTimeAndWallTime,
ReplicationCoordinator::DataConsistency consistency) {
_recordApplied(newOpTimeAndWallTime, consistency);
};
protected:
void _recordApplied(const OpTimeAndWallTime& newOpTimeAndWallTime,
ReplicationCoordinator::DataConsistency consistency) {
// We have to use setMyLastAppliedOpTimeAndWallTimeForward since this thread races with
// ReplicationExternalStateImpl::onTransitionToPrimary.
_replCoord->setMyLastAppliedOpTimeAndWallTimeForward(newOpTimeAndWallTime, consistency);
}
void _recordDurable(const OpTimeAndWallTime& newOpTimeAndWallTime) {
// We have to use setMyLastDurableOpTimeAndWallTimeFoward since this thread races with
// ReplicationExternalStateImpl::onTransitionToPrimary.
_replCoord->setMyLastDurableOpTimeAndWallTimeForward(newOpTimeAndWallTime);
}
private:
// Used to update the replication system's progress.
ReplicationCoordinator* _replCoord;
};
class ApplyBatchFinalizerForJournal : public ApplyBatchFinalizer {
public:
ApplyBatchFinalizerForJournal(ReplicationCoordinator* replCoord)
: ApplyBatchFinalizer(replCoord),
_waiterThread{&ApplyBatchFinalizerForJournal::_run, this} {};
~ApplyBatchFinalizerForJournal();
void record(const OpTimeAndWallTime& newOpTimeAndWallTime,
ReplicationCoordinator::DataConsistency consistency) override;
private:
/**
* Loops continuously, waiting for writes to be flushed to disk and then calls
* ReplicationCoordinator::setMyLastOptime with _latestOpTime.
* Terminates once _shutdownSignaled is set true.
*/
void _run();
// Protects _cond, _shutdownSignaled, and _latestOpTime.
Mutex _mutex = MONGO_MAKE_LATCH("OplogApplierImpl::_mutex");
// Used to alert our thread of a new OpTime.
stdx::condition_variable _cond;
// The next OpTime to set as the ReplicationCoordinator's lastOpTime after flushing.
OpTimeAndWallTime _latestOpTimeAndWallTime;
// Once this is set to true the _run method will terminate.
bool _shutdownSignaled = false;
// Thread that will _run(). Must be initialized last as it depends on the other variables.
stdx::thread _waiterThread;
};
ApplyBatchFinalizerForJournal::~ApplyBatchFinalizerForJournal() {
stdx::unique_lock<Latch> lock(_mutex);
_shutdownSignaled = true;
_cond.notify_all();
lock.unlock();
_waiterThread.join();
}
void ApplyBatchFinalizerForJournal::record(const OpTimeAndWallTime& newOpTimeAndWallTime,
ReplicationCoordinator::DataConsistency consistency) {
_recordApplied(newOpTimeAndWallTime, consistency);
stdx::unique_lock<Latch> lock(_mutex);
_latestOpTimeAndWallTime = newOpTimeAndWallTime;
_cond.notify_all();
}
void ApplyBatchFinalizerForJournal::_run() {
Client::initThread("ApplyBatchFinalizerForJournal");
while (true) {
OpTimeAndWallTime latestOpTimeAndWallTime = {OpTime(), Date_t()};
{
stdx::unique_lock<Latch> lock(_mutex);
while (_latestOpTimeAndWallTime.opTime.isNull() && !_shutdownSignaled) {
_cond.wait(lock);
}
if (_shutdownSignaled) {
return;
}
latestOpTimeAndWallTime = _latestOpTimeAndWallTime;
_latestOpTimeAndWallTime = {OpTime(), Date_t()};
}
auto opCtx = cc().makeOperationContext();
opCtx->recoveryUnit()->waitUntilDurable(opCtx.get());
_recordDurable(latestOpTimeAndWallTime);
}
}
} // namespace
OplogApplierImpl::OplogApplierImpl(executor::TaskExecutor* executor,
OplogBuffer* oplogBuffer,
Observer* observer,
ReplicationCoordinator* replCoord,
ReplicationConsistencyMarkers* consistencyMarkers,
StorageInterface* storageInterface,
const OplogApplier::Options& options,
ThreadPool* writerPool)
: OplogApplier(executor, oplogBuffer, observer, options),
_replCoord(replCoord),
_writerPool(writerPool),
_storageInterface(storageInterface),
_consistencyMarkers(consistencyMarkers),
_beginApplyingOpTime(options.beginApplyingOpTime) {}
void OplogApplierImpl::_run(OplogBuffer* oplogBuffer) {
// Start up a thread from the batcher to pull from the oplog buffer into the batcher's oplog
// batch.
_oplogBatcher->startup(_storageInterface);
ON_BLOCK_EXIT([this] { _oplogBatcher->shutdown(); });
// We don't start data replication for arbiters at all and it's not allowed to reconfig
// arbiterOnly field for any member.
invariant(!_replCoord->getMemberState().arbiter());
std::unique_ptr<ApplyBatchFinalizer> finalizer{
getGlobalServiceContext()->getStorageEngine()->isDurable()
? new ApplyBatchFinalizerForJournal(_replCoord)
: new ApplyBatchFinalizer(_replCoord)};
while (true) { // Exits on message from OplogBatcher.
// Use a new operation context each iteration, as otherwise we may appear to use a single
// collection name to refer to collections with different UUIDs.
const ServiceContext::UniqueOperationContext opCtxPtr = cc().makeOperationContext();
OperationContext& opCtx = *opCtxPtr;
// This code path gets used during elections, so it should not be subject to Flow Control.
// It is safe to exclude this operation context from Flow Control here because this code
// path only gets used on secondaries or on a node transitioning to primary.
opCtx.setShouldParticipateInFlowControl(false);
// For pausing replication in tests.
if (MONGO_unlikely(rsSyncApplyStop.shouldFail())) {
log() << "Oplog Applier - rsSyncApplyStop fail point enabled. Blocking until fail "
"point is disabled.";
rsSyncApplyStop.pauseWhileSet(&opCtx);
}
// Transition to SECONDARY state, if possible.
_replCoord->finishRecoveryIfEligible(&opCtx);
// Blocks up to a second waiting for a batch to be ready to apply. If one doesn't become
// ready in time, we'll loop again so we can do the above checks periodically.
OplogBatch ops = _oplogBatcher->getNextBatch(Seconds(1));
if (ops.empty()) {
if (ops.mustShutdown()) {
// Shut down and exit oplog application loop.
return;
}
if (MONGO_unlikely(rsSyncApplyStop.shouldFail())) {
continue;
}
if (ops.termWhenExhausted()) {
// Signal drain complete if we're in Draining state and the buffer is empty.
// Since we check the states of batcher and oplog buffer without synchronization,
// they can be stale. We make sure the applier is still draining in the given term
// before and after the check, so that if the oplog buffer was exhausted, then
// it still will be.
_replCoord->signalDrainComplete(&opCtx, *ops.termWhenExhausted());
}
continue; // Try again.
}
// Extract some info from ops that we'll need after releasing the batch below.
const auto firstOpTimeInBatch = ops.front().getOpTime();
const auto lastOpInBatch = ops.back();
const auto lastOpTimeInBatch = lastOpInBatch.getOpTime();
const auto lastWallTimeInBatch = lastOpInBatch.getWallClockTime();
const auto lastAppliedOpTimeAtStartOfBatch = _replCoord->getMyLastAppliedOpTime();
// Make sure the oplog doesn't go back in time or repeat an entry.
if (firstOpTimeInBatch <= lastAppliedOpTimeAtStartOfBatch) {
fassert(34361,
Status(ErrorCodes::OplogOutOfOrder,
str::stream() << "Attempted to apply an oplog entry ("
<< firstOpTimeInBatch.toString()
<< ") which is not greater than our last applied OpTime ("
<< lastAppliedOpTimeAtStartOfBatch.toString() << ")."));
}
// Don't allow the fsync+lock thread to see intermediate states of batch application.
stdx::lock_guard<SimpleMutex> fsynclk(filesLockedFsync);
// Apply the operations in this batch. '_applyOplogBatch' returns the optime of the
// last op that was applied, which should be the last optime in the batch.
auto swLastOpTimeAppliedInBatch = _applyOplogBatch(&opCtx, ops.releaseBatch());
if (swLastOpTimeAppliedInBatch.getStatus().code() == ErrorCodes::InterruptedAtShutdown) {
// If an operation was interrupted at shutdown, fail the batch without advancing
// appliedThrough as if this were an unclean shutdown. This ensures the stable timestamp
// does not advance, and a checkpoint cannot be taken at a timestamp that includes this
// batch. On startup, we will recover from an earlier stable checkpoint and apply the
// operations from this batch again.
return;
}
fassertNoTrace(34437, swLastOpTimeAppliedInBatch);
invariant(swLastOpTimeAppliedInBatch.getValue() == lastOpTimeInBatch);
// Update various things that care about our last applied optime. Tests rely on 1 happening
// before 2 even though it isn't strictly necessary.
// 1. Persist our "applied through" optime to disk.
_consistencyMarkers->setAppliedThrough(&opCtx, lastOpTimeInBatch);
// 2. Ensure that the last applied op time hasn't changed since the start of this batch.
const auto lastAppliedOpTimeAtEndOfBatch = _replCoord->getMyLastAppliedOpTime();
invariant(lastAppliedOpTimeAtStartOfBatch == lastAppliedOpTimeAtEndOfBatch,
str::stream() << "the last known applied OpTime has changed from "
<< lastAppliedOpTimeAtStartOfBatch.toString() << " to "
<< lastAppliedOpTimeAtEndOfBatch.toString()
<< " in the middle of batch application");
// For RaftMongo.tla trace-checking, dump the oplog including new entries, before the new
// entries are visible and cause other RaftMongo events.
_replCoord->tlaPlusRaftMongoEvent(
&opCtx, RaftMongoSpecActionEnum::kAppendOplog, lastOpTimeInBatch.getTimestamp());
// 3. Update oplog visibility by notifying the storage engine of the new oplog entries.
const bool orderedCommit = true;
_storageInterface->oplogDiskLocRegister(
&opCtx, lastOpTimeInBatch.getTimestamp(), orderedCommit);
// 4. Finalize this batch. We are at a consistent optime if our current optime is >= the
// current 'minValid' optime. Note that recording the lastOpTime in the finalizer includes
// advancing the global timestamp to at least its timestamp.
const auto minValid = _consistencyMarkers->getMinValid(&opCtx);
auto consistency = (lastOpTimeInBatch >= minValid)
? ReplicationCoordinator::DataConsistency::Consistent
: ReplicationCoordinator::DataConsistency::Inconsistent;
// The finalizer advances the global timestamp to lastOpTimeInBatch.
finalizer->record({lastOpTimeInBatch, lastWallTimeInBatch}, consistency);
}
}
// Schedules the writes to the oplog for 'ops' into threadPool. The caller must guarantee that
// 'ops' stays valid until all scheduled work in the thread pool completes.
void scheduleWritesToOplog(OperationContext* opCtx,
StorageInterface* storageInterface,
ThreadPool* writerPool,
const std::vector<OplogEntry>& ops) {
auto makeOplogWriterForRange = [storageInterface, &ops](size_t begin, size_t end) {
// The returned function will be run in a separate thread after this returns. Therefore all
// captures other than 'ops' must be by value since they will not be available. The caller
// guarantees that 'ops' will stay in scope until the spawned threads complete.
return [storageInterface, &ops, begin, end](auto status) {
invariant(status);
auto opCtx = cc().makeOperationContext();
// This code path is only executed on secondaries and initial syncing nodes, so it is
// safe to exclude any writes from Flow Control.
opCtx->setShouldParticipateInFlowControl(false);
UnreplicatedWritesBlock uwb(opCtx.get());
ShouldNotConflictWithSecondaryBatchApplicationBlock shouldNotConflictBlock(
opCtx->lockState());
std::vector<InsertStatement> docs;
docs.reserve(end - begin);
for (size_t i = begin; i < end; i++) {
// Add as unowned BSON to avoid unnecessary ref-count bumps.
// 'ops' will outlive 'docs' so the BSON lifetime will be guaranteed.
docs.emplace_back(InsertStatement{ops[i].getRaw(),
ops[i].getOpTime().getTimestamp(),
ops[i].getOpTime().getTerm()});
}
fassert(40141,
storageInterface->insertDocuments(
opCtx.get(), NamespaceString::kRsOplogNamespace, docs));
};
};
// We want to be able to take advantage of bulk inserts so we don't use multiple threads if it
// would result too little work per thread. This also ensures that we can amortize the
// setup/teardown overhead across many writes.
const size_t kMinOplogEntriesPerThread = 16;
const bool enoughToMultiThread =
ops.size() >= kMinOplogEntriesPerThread * writerPool->getStats().numThreads;
// Only doc-locking engines support parallel writes to the oplog because they are required to
// ensure that oplog entries are ordered correctly, even if inserted out-of-order. Additionally,
// there would be no way to take advantage of multiple threads if a storage engine doesn't
// support document locking.
if (!enoughToMultiThread ||
!opCtx->getServiceContext()->getStorageEngine()->supportsDocLocking()) {
writerPool->schedule(makeOplogWriterForRange(0, ops.size()));
return;
}
const size_t numOplogThreads = writerPool->getStats().numThreads;
const size_t numOpsPerThread = ops.size() / numOplogThreads;
for (size_t thread = 0; thread < numOplogThreads; thread++) {
size_t begin = thread * numOpsPerThread;
size_t end = (thread == numOplogThreads - 1) ? ops.size() : begin + numOpsPerThread;
writerPool->schedule(makeOplogWriterForRange(begin, end));
}
}
StatusWith<OpTime> OplogApplierImpl::_applyOplogBatch(OperationContext* opCtx,
std::vector<OplogEntry> ops) {
invariant(!ops.empty());
LOG(2) << "replication batch size is " << ops.size();
// Stop all readers until we're done. This also prevents doc-locking engines from deleting old
// entries from the oplog until we finish writing.
Lock::ParallelBatchWriterMode pbwm(opCtx->lockState());
invariant(_replCoord);
if (_replCoord->getApplierState() == ReplicationCoordinator::ApplierState::Stopped) {
severe() << "attempting to replicate ops while primary";
return {ErrorCodes::CannotApplyOplogWhilePrimary,
"attempting to replicate ops while primary"};
}
// Increment the batch size stat.
oplogApplicationBatchSize.increment(ops.size());
std::vector<WorkerMultikeyPathInfo> multikeyVector(_writerPool->getStats().numThreads);
{
// Each node records cumulative batch application stats for itself using this timer.
TimerHolder timer(&applyBatchStats);
// We must wait for the all work we've dispatched to complete before leaving this block
// because the spawned threads refer to objects on the stack
ON_BLOCK_EXIT([&] { _writerPool->waitForIdle(); });
// Write batch of ops into oplog.
if (!getOptions().skipWritesToOplog) {
_consistencyMarkers->setOplogTruncateAfterPoint(opCtx, ops.front().getTimestamp());
scheduleWritesToOplog(opCtx, _storageInterface, _writerPool, ops);
}
// Holds 'pseudo operations' generated by secondaries to aid in replication.
// Keep in scope until all operations in 'ops' and 'derivedOps' have been applied.
// Pseudo operations include:
// - applyOps operations expanded to individual ops.
// - ops to update config.transactions. Normal writes to config.transactions in the
// primary don't create an oplog entry, so extract info from writes with transactions
// and create a pseudo oplog.
std::vector<std::vector<OplogEntry>> derivedOps;
std::vector<std::vector<const OplogEntry*>> writerVectors(
_writerPool->getStats().numThreads);
fillWriterVectors(opCtx, &ops, &writerVectors, &derivedOps);
// Wait for writes to finish before applying ops.
_writerPool->waitForIdle();
// Use this fail point to hold the PBWM lock after we have written the oplog entries but
// before we have applied them.
if (MONGO_unlikely(pauseBatchApplicationAfterWritingOplogEntries.shouldFail())) {
log() << "pauseBatchApplicationAfterWritingOplogEntries fail point enabled. Blocking "
"until fail point is disabled.";
pauseBatchApplicationAfterWritingOplogEntries.pauseWhileSet(opCtx);
}
// Reset consistency markers in case the node fails while applying ops.
if (!getOptions().skipWritesToOplog) {
_consistencyMarkers->setOplogTruncateAfterPoint(opCtx, Timestamp());
_consistencyMarkers->setMinValidToAtLeast(opCtx, ops.back().getOpTime());
}
{
std::vector<Status> statusVector(_writerPool->getStats().numThreads, Status::OK());
// Doles out all the work to the writer pool threads. writerVectors is not modified,
// but applyOplogBatchPerWorker will modify the vectors that it contains.
invariant(writerVectors.size() == statusVector.size());
for (size_t i = 0; i < writerVectors.size(); i++) {
if (writerVectors[i].empty())
continue;
_writerPool->schedule(
[this,
&writer = writerVectors.at(i),
&status = statusVector.at(i),
&multikeyVector = multikeyVector.at(i)](auto scheduleStatus) {
invariant(scheduleStatus);
auto opCtx = cc().makeOperationContext();
// This code path is only executed on secondaries and initial syncing nodes,
// so it is safe to exclude any writes from Flow Control.
opCtx->setShouldParticipateInFlowControl(false);
status = opCtx->runWithoutInterruptionExceptAtGlobalShutdown([&] {
return applyOplogBatchPerWorker(opCtx.get(), &writer, &multikeyVector);
});
});
}
_writerPool->waitForIdle();
// If any of the statuses is not ok, return error.
for (auto it = statusVector.cbegin(); it != statusVector.cend(); ++it) {
const auto& status = *it;
if (!status.isOK()) {
severe()
<< "Failed to apply batch of operations. Number of operations in batch: "
<< ops.size() << ". First operation: " << redact(ops.front().toBSON())
<< ". Last operation: " << redact(ops.back().toBSON())
<< ". Oplog application failed in writer thread "
<< std::distance(statusVector.cbegin(), it) << ": " << redact(status);
return status;
}
}
}
}
// Tell the storage engine to flush the journal now that a replication batch has completed. This
// means that all the writes associated with the oplog entries in the batch are finished and no
// new writes with timestamps associated with those oplog entries will show up in the future. We
// want to flush the journal as soon as possible in order to free ops waiting with 'j' write
// concern.
const auto storageEngine = opCtx->getServiceContext()->getStorageEngine();
storageEngine->triggerJournalFlush();
// Use this fail point to hold the PBWM lock and prevent the batch from completing.
if (MONGO_unlikely(pauseBatchApplicationBeforeCompletion.shouldFail())) {
log() << "pauseBatchApplicationBeforeCompletion fail point enabled. Blocking until fail "
"point is disabled.";
while (MONGO_unlikely(pauseBatchApplicationBeforeCompletion.shouldFail())) {
if (inShutdown()) {
severe() << "Turn off pauseBatchApplicationBeforeCompletion before attempting "
"clean shutdown";
fassertFailedNoTrace(50798);
}
sleepmillis(100);
}
}
Timestamp firstTimeInBatch = ops.front().getTimestamp();
// Set any indexes to multikey that this batch ignored. This must be done while holding the
// parallel batch writer mode lock.
for (WorkerMultikeyPathInfo infoVector : multikeyVector) {
for (MultikeyPathInfo info : infoVector) {
// We timestamp every multikey write with the first timestamp in the batch. It is always
// safe to set an index as multikey too early, just not too late. We conservatively pick
// the first timestamp in the batch since we do not have enough information to find out
// the timestamp of the first write that set the given multikey path.
fassert(50686,
_storageInterface->setIndexIsMultikey(
opCtx, info.nss, info.indexName, info.multikeyPaths, firstTimeInBatch));
}
}
// Increment the counter for the number of ops applied during catchup if the node is in catchup
// mode.
_replCoord->incrementNumCatchUpOpsIfCatchingUp(ops.size());
// We have now written all database writes and updated the oplog to match.
return ops.back().getOpTime();
}
/**
* ops - This only modifies the isForCappedCollection field on each op. It does not alter the ops
* vector in any other way.
* writerVectors - Set of operations for each worker thread to apply.
* derivedOps - If provided, this function inserts a decomposition of applyOps operations
* and instructions for updating the transactions table. Required if processing oplogs
* with transactions.
* sessionUpdateTracker - if provided, keeps track of session info from ops.
*/
void OplogApplierImpl::_deriveOpsAndFillWriterVectors(
OperationContext* opCtx,
std::vector<OplogEntry>* ops,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
std::vector<std::vector<OplogEntry>>* derivedOps,
SessionUpdateTracker* sessionUpdateTracker) noexcept {
LogicalSessionIdMap<std::vector<OplogEntry*>> partialTxnOps;
CachedCollectionProperties collPropertiesCache;
for (auto&& op : *ops) {
// If the operation's optime is before or the same as the beginApplyingOpTime we don't want
// to apply it, so don't include it in writerVectors.
if (op.getOpTime() <= getOptions().beginApplyingOpTime) {
continue;
}
auto hashedNs = StringMapHasher().hashed_key(op.getNss().ns());
// Reduce the hash from 64bit down to 32bit, just to allow combinations with murmur3 later
// on. Bit depth not important, we end up just doing integer modulo with this in the end.
// The hash function should provide entropy in the lower bits as it's used in hash tables.
uint32_t hash = static_cast<uint32_t>(hashedNs.hash());
// We need to track all types of ops, including type 'n' (these are generated from chunk
// migrations).
if (sessionUpdateTracker) {
if (auto newOplogWrites = sessionUpdateTracker->updateSession(op)) {
derivedOps->emplace_back(std::move(*newOplogWrites));
addDerivedOps(opCtx, &derivedOps->back(), writerVectors, &collPropertiesCache);
}
}
// If this entry is part of a multi-oplog-entry transaction, ignore it until the commit.
// We must save it here because we are not guaranteed it has been written to the oplog
// yet.
// We also do this for prepare during initial sync.
if (op.isPartialTransaction() ||
(op.shouldPrepare() && getOptions().mode == OplogApplication::Mode::kInitialSync)) {
auto& partialTxnList = partialTxnOps[*op.getSessionId()];
// If this operation belongs to an existing partial transaction, partialTxnList
// must contain the previous operations of the transaction.
invariant(partialTxnList.empty() ||
partialTxnList.front()->getTxnNumber() == op.getTxnNumber());
partialTxnList.push_back(&op);
continue;
}
if (op.getCommandType() == OplogEntry::CommandType::kAbortTransaction) {
auto& partialTxnList = partialTxnOps[*op.getSessionId()];
partialTxnList.clear();
}
if (op.isCrudOpType())
processCrudOp(opCtx, &op, &hash, &hashedNs, &collPropertiesCache);
// Extract applyOps operations and fill writers with extracted operations using this
// function.
if (op.isTerminalApplyOps()) {
auto logicalSessionId = op.getSessionId();
// applyOps entries generated by a transaction must have a sessionId and a
// transaction number.
if (logicalSessionId && op.getTxnNumber()) {
// On commit of unprepared transactions, get transactional operations from the
// oplog and fill writers with those operations.
// Flush partialTxnList operations for current transaction.
auto& partialTxnList = partialTxnOps[*logicalSessionId];
derivedOps->emplace_back(
readTransactionOperationsFromOplogChain(opCtx, op, partialTxnList));
partialTxnList.clear();
// Transaction entries cannot have different session updates.
addDerivedOps(opCtx, &derivedOps->back(), writerVectors, &collPropertiesCache);
} else {
// The applyOps entry was not generated as part of a transaction.
invariant(!op.getPrevWriteOpTimeInTransaction());
derivedOps->emplace_back(ApplyOps::extractOperations(op));
// Nested entries cannot have different session updates.
addDerivedOps(opCtx, &derivedOps->back(), writerVectors, &collPropertiesCache);
}
continue;
}
// If we see a commitTransaction command that is a part of a prepared transaction during
// initial sync, find the prepare oplog entry, extract applyOps operations, and fill writers
// with the extracted operations.
if (op.isPreparedCommit() && (getOptions().mode == OplogApplication::Mode::kInitialSync)) {
auto logicalSessionId = op.getSessionId();
auto& partialTxnList = partialTxnOps[*logicalSessionId];
derivedOps->emplace_back(
readTransactionOperationsFromOplogChain(opCtx, op, partialTxnList));
partialTxnList.clear();
addDerivedOps(opCtx, &derivedOps->back(), writerVectors, &collPropertiesCache);
continue;
}
addToWriterVector(&op, writerVectors, hash);
}
}
void OplogApplierImpl::fillWriterVectors(
OperationContext* opCtx,
std::vector<OplogEntry>* ops,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
std::vector<std::vector<OplogEntry>>* derivedOps) noexcept {
SessionUpdateTracker sessionUpdateTracker;
_deriveOpsAndFillWriterVectors(opCtx, ops, writerVectors, derivedOps, &sessionUpdateTracker);
auto newOplogWrites = sessionUpdateTracker.flushAll();
if (!newOplogWrites.empty()) {
derivedOps->emplace_back(std::move(newOplogWrites));
_deriveOpsAndFillWriterVectors(
opCtx, &derivedOps->back(), writerVectors, derivedOps, nullptr);
}
}
Status applyOplogEntryOrGroupedInserts(OperationContext* opCtx,
const OplogEntryOrGroupedInserts& entryOrGroupedInserts,
OplogApplication::Mode oplogApplicationMode) {
// Guarantees that applyOplogEntryOrGroupedInserts' context matches that of its calling
// function, applyOplogBatchPerWorker.
invariant(!opCtx->writesAreReplicated());
invariant(documentValidationDisabled(opCtx));
auto op = entryOrGroupedInserts.getOp();
// Count each log op application as a separate operation, for reporting purposes
CurOp individualOp(opCtx);
const NamespaceString nss(op.getNss());
auto incrementOpsAppliedStats = [] { opsAppliedStats.increment(1); };
auto clockSource = opCtx->getServiceContext()->getFastClockSource();
auto applyStartTime = clockSource->now();
if (MONGO_unlikely(hangAfterRecordingOpApplicationStartTime.shouldFail())) {
log() << "applyOplogEntryOrGroupedInserts - fail point "
"hangAfterRecordingOpApplicationStartTime "
"enabled. "
<< "Blocking until fail point is disabled. ";
hangAfterRecordingOpApplicationStartTime.pauseWhileSet();
}
auto opType = op.getOpType();
if (opType == OpTypeEnum::kNoop) {
incrementOpsAppliedStats();
auto opObj = op.getObject();
if (opObj.hasField(ReplicationCoordinator::newPrimaryMsgField) &&
opObj.getField(ReplicationCoordinator::newPrimaryMsgField).str() ==
ReplicationCoordinator::newPrimaryMsg) {
ReplicationMetrics::get(opCtx).setParticipantNewTermDates(op.getWallClockTime(),
applyStartTime);
}
return Status::OK();
} else if (OplogEntry::isCrudOpType(opType)) {
auto status =
writeConflictRetry(opCtx, "applyOplogEntryOrGroupedInserts_CRUD", nss.ns(), [&] {
// Need to throw instead of returning a status for it to be properly ignored.
try {
AutoGetCollection autoColl(opCtx,
getNsOrUUID(nss, op),
fixLockModeForSystemDotViewsChanges(nss, MODE_IX));
auto db = autoColl.getDb();
uassert(ErrorCodes::NamespaceNotFound,
str::stream() << "missing database (" << nss.db() << ")",
db);
OldClientContext ctx(opCtx, autoColl.getNss().ns(), db);
// We convert updates to upserts when not in initial sync because after rollback
// and during startup we may replay an update after a delete and crash since we
// do not ignore errors. In initial sync we simply ignore these update errors so
// there is no reason to upsert.
//
// TODO (SERVER-21700): Never upsert during oplog application unless an external
// applyOps wants to. We should ignore these errors intelligently while in
// RECOVERING and STARTUP mode (similar to initial sync) instead so we do not
// accidentally ignore real errors.
bool shouldAlwaysUpsert =
(oplogApplicationMode != OplogApplication::Mode::kInitialSync);
Status status = applyOperation_inlock(opCtx,
db,
entryOrGroupedInserts,
shouldAlwaysUpsert,
oplogApplicationMode,
incrementOpsAppliedStats);
if (!status.isOK() && status.code() == ErrorCodes::WriteConflict) {
throw WriteConflictException();
}
return status;
} catch (ExceptionFor<ErrorCodes::NamespaceNotFound>& ex) {
// Delete operations on non-existent namespaces can be treated as successful for
// idempotency reasons.
// During RECOVERING mode, we ignore NamespaceNotFound for all CRUD ops since
// storage does not wait for drops to be checkpointed (SERVER-33161).
if (opType == OpTypeEnum::kDelete ||
oplogApplicationMode == OplogApplication::Mode::kRecovering) {
return Status::OK();
}
ex.addContext(str::stream() << "Failed to apply operation: "
<< redact(entryOrGroupedInserts.toBSON()));
throw;
}
});
return finishAndLogApply(clockSource, status, applyStartTime, entryOrGroupedInserts);
} else if (opType == OpTypeEnum::kCommand) {
auto status =
writeConflictRetry(opCtx, "applyOplogEntryOrGroupedInserts_command", nss.ns(), [&] {
// A special case apply for commands to avoid implicit database creation.
Status status = applyCommand_inlock(opCtx, op, oplogApplicationMode);
incrementOpsAppliedStats();
return status;
});
return finishAndLogApply(clockSource, status, applyStartTime, entryOrGroupedInserts);
}
MONGO_UNREACHABLE;
}
Status OplogApplierImpl::applyOplogBatchPerWorker(OperationContext* opCtx,
std::vector<const OplogEntry*>* ops,
WorkerMultikeyPathInfo* workerMultikeyPathInfo) {
UnreplicatedWritesBlock uwb(opCtx);
DisableDocumentValidation validationDisabler(opCtx);
// Since we swap the locker in stash / unstash transaction resources,
// ShouldNotConflictWithSecondaryBatchApplicationBlock will touch the locker that has been
// destroyed by unstash in its destructor. Thus we set the flag explicitly.
opCtx->lockState()->setShouldConflictWithSecondaryBatchApplication(false);
// Explicitly start future read transactions without a timestamp.
opCtx->recoveryUnit()->setTimestampReadSource(RecoveryUnit::ReadSource::kNoTimestamp);
// When querying indexes, we return the record matching the key if it exists, or an adjacent
// document. This means that it is possible for us to hit a prepare conflict if we query for an
// incomplete key and an adjacent key is prepared.
// We ignore prepare conflicts on secondaries because they may encounter prepare conflicts that
// did not occur on the primary.
opCtx->recoveryUnit()->setPrepareConflictBehavior(
PrepareConflictBehavior::kIgnoreConflictsAllowWrites);
stableSortByNamespace(ops);
const auto oplogApplicationMode = getOptions().mode;
InsertGroup insertGroup(ops, opCtx, oplogApplicationMode);
{ // Ensure that the MultikeyPathTracker stops tracking paths.
ON_BLOCK_EXIT([opCtx] { MultikeyPathTracker::get(opCtx).stopTrackingMultikeyPathInfo(); });
MultikeyPathTracker::get(opCtx).startTrackingMultikeyPathInfo();
for (auto it = ops->cbegin(); it != ops->cend(); ++it) {
const OplogEntry& entry = **it;
// If we are successful in grouping and applying inserts, advance the current iterator
// past the end of the inserted group of entries.
auto groupResult = insertGroup.groupAndApplyInserts(it);
if (groupResult.isOK()) {
it = groupResult.getValue();
continue;
}
// If we didn't create a group, try to apply the op individually.
try {
const Status status =
applyOplogEntryOrGroupedInserts(opCtx, &entry, oplogApplicationMode);
if (!status.isOK()) {
// Tried to apply an update operation but the document is missing, there must be
// a delete operation for the document later in the oplog.
if (status == ErrorCodes::UpdateOperationFailed &&
oplogApplicationMode == OplogApplication::Mode::kInitialSync) {
continue;
}
severe() << "Error applying operation (" << redact(entry.toBSON())
<< "): " << causedBy(redact(status));
return status;
}
} catch (const DBException& e) {
// SERVER-24927 If we have a NamespaceNotFound exception, then this document will be
// dropped before initial sync or recovery ends anyways and we should ignore it.
if (e.code() == ErrorCodes::NamespaceNotFound && entry.isCrudOpType() &&
getOptions().allowNamespaceNotFoundErrorsOnCrudOps) {
continue;
}
severe() << "writer worker caught exception: " << redact(e)
<< " on: " << redact(entry.toBSON());
return e.toStatus();
}
}
}
invariant(!MultikeyPathTracker::get(opCtx).isTrackingMultikeyPathInfo());
invariant(workerMultikeyPathInfo->empty());
auto newPaths = MultikeyPathTracker::get(opCtx).getMultikeyPathInfo();
if (!newPaths.empty()) {
workerMultikeyPathInfo->swap(newPaths);
}
return Status::OK();
}
} // namespace repl
} // namespace mongo
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