/
initial_syncer.cpp
1626 lines (1421 loc) · 69 KB
/
initial_syncer.cpp
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/**
* Copyright (C) 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/platform/basic.h"
#include "initial_syncer.h"
#include <algorithm>
#include <utility>
#include "mongo/base/counter.h"
#include "mongo/base/status.h"
#include "mongo/bson/simple_bsonobj_comparator.h"
#include "mongo/bson/util/bson_extract.h"
#include "mongo/client/fetcher.h"
#include "mongo/client/remote_command_retry_scheduler.h"
#include "mongo/db/commands/feature_compatibility_version.h"
#include "mongo/db/commands/server_status_metric.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/repl/databases_cloner.h"
#include "mongo/db/repl/initial_sync_state.h"
#include "mongo/db/repl/member_state.h"
#include "mongo/db/repl/oplog_buffer.h"
#include "mongo/db/repl/oplog_fetcher.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/repl/replication_process.h"
#include "mongo/db/repl/storage_interface.h"
#include "mongo/db/repl/sync_source_selector.h"
#include "mongo/db/server_parameters.h"
#include "mongo/executor/task_executor.h"
#include "mongo/rpc/metadata/repl_set_metadata.h"
#include "mongo/stdx/memory.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/destructor_guard.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
#include "mongo/util/scopeguard.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace repl {
// Failpoint for initial sync
MONGO_FP_DECLARE(failInitialSyncWithBadHost);
// Failpoint which fails initial sync and leaves an oplog entry in the buffer.
MONGO_FP_DECLARE(failInitSyncWithBufferedEntriesLeft);
// Failpoint which causes the initial sync function to hang before copying databases.
MONGO_FP_DECLARE(initialSyncHangBeforeCopyingDatabases);
// Failpoint which causes the initial sync function to hang before finishing.
MONGO_FP_DECLARE(initialSyncHangBeforeFinish);
// Failpoint which causes the initial sync function to hang before calling shouldRetry on a failed
// operation.
MONGO_FP_DECLARE(initialSyncHangBeforeGettingMissingDocument);
// Failpoint which stops the applier.
MONGO_FP_DECLARE(rsSyncApplyStop);
namespace {
using namespace executor;
using CallbackArgs = executor::TaskExecutor::CallbackArgs;
using Event = executor::TaskExecutor::EventHandle;
using Handle = executor::TaskExecutor::CallbackHandle;
using Operations = MultiApplier::Operations;
using QueryResponseStatus = StatusWith<Fetcher::QueryResponse>;
using UniqueLock = stdx::unique_lock<stdx::mutex>;
using LockGuard = stdx::lock_guard<stdx::mutex>;
// 16MB max batch size / 12 byte min doc size * 10 (for good measure) = defaultBatchSize to use.
const auto defaultBatchSize = (16 * 1024 * 1024) / 12 * 10;
// The number of attempts to connect to a sync source.
MONGO_EXPORT_SERVER_PARAMETER(numInitialSyncConnectAttempts, int, 10);
// The number of attempts to call find on the remote oplog.
MONGO_EXPORT_SERVER_PARAMETER(numInitialSyncOplogFindAttempts, int, 3);
// The batchSize to use for the find/getMore queries called by the OplogFetcher
MONGO_EXPORT_STARTUP_SERVER_PARAMETER(initialSyncOplogFetcherBatchSize, int, defaultBatchSize);
// The number of initial sync attempts that have failed since server startup. Each instance of
// InitialSyncer may run multiple attempts to fulfill an initial sync request that is triggered
// when InitialSyncer::startup() is called.
Counter64 initialSyncFailedAttempts;
// The number of initial sync requests that have been requested and failed. Each instance of
// InitialSyncer (upon successful startup()) corresponds to a single initial sync request.
// This value does not include the number of times where a InitialSyncer is created successfully
// but failed in startup().
Counter64 initialSyncFailures;
// The number of initial sync requests that have been requested and completed successfully. Each
// instance of InitialSyncer corresponds to a single initial sync request.
Counter64 initialSyncCompletes;
ServerStatusMetricField<Counter64> displaySSInitialSyncFailedAttempts(
"repl.initialSync.failedAttempts", &initialSyncFailedAttempts);
ServerStatusMetricField<Counter64> displaySSInitialSyncFailures("repl.initialSync.failures",
&initialSyncFailures);
ServerStatusMetricField<Counter64> displaySSInitialSyncCompleted("repl.initialSync.completed",
&initialSyncCompletes);
ServiceContext::UniqueOperationContext makeOpCtx() {
return cc().makeOperationContext();
}
StatusWith<Timestamp> parseTimestampStatus(const QueryResponseStatus& fetchResult) {
if (!fetchResult.isOK()) {
return fetchResult.getStatus();
} else {
const auto docs = fetchResult.getValue().documents;
const auto hasDoc = docs.begin() != docs.end();
if (!hasDoc || !docs.begin()->hasField("ts")) {
return {ErrorCodes::FailedToParse, "Could not find an oplog entry with 'ts' field."};
} else {
return {docs.begin()->getField("ts").timestamp()};
}
}
}
StatusWith<OpTimeWithHash> parseOpTimeWithHash(const QueryResponseStatus& fetchResult) {
if (!fetchResult.isOK()) {
return fetchResult.getStatus();
}
const auto docs = fetchResult.getValue().documents;
const auto hasDoc = docs.begin() != docs.end();
return hasDoc
? AbstractOplogFetcher::parseOpTimeWithHash(docs.front())
: StatusWith<OpTimeWithHash>{ErrorCodes::NoMatchingDocument, "no oplog entry found"};
}
} // namespace
InitialSyncer::InitialSyncer(
InitialSyncerOptions opts,
std::unique_ptr<DataReplicatorExternalState> dataReplicatorExternalState,
StorageInterface* storage,
ReplicationProcess* replicationProcess,
const OnCompletionFn& onCompletion)
: _fetchCount(0),
_opts(opts),
_dataReplicatorExternalState(std::move(dataReplicatorExternalState)),
_exec(_dataReplicatorExternalState->getTaskExecutor()),
_storage(storage),
_replicationProcess(replicationProcess),
_onCompletion(onCompletion) {
uassert(ErrorCodes::BadValue, "task executor cannot be null", _exec);
uassert(ErrorCodes::BadValue, "invalid storage interface", _storage);
uassert(ErrorCodes::BadValue, "invalid replication process", _replicationProcess);
uassert(ErrorCodes::BadValue, "invalid getMyLastOptime function", _opts.getMyLastOptime);
uassert(ErrorCodes::BadValue, "invalid setMyLastOptime function", _opts.setMyLastOptime);
uassert(ErrorCodes::BadValue, "invalid resetOptimes function", _opts.resetOptimes);
uassert(ErrorCodes::BadValue, "invalid getSlaveDelay function", _opts.getSlaveDelay);
uassert(ErrorCodes::BadValue, "invalid sync source selector", _opts.syncSourceSelector);
uassert(ErrorCodes::BadValue, "callback function cannot be null", _onCompletion);
}
InitialSyncer::~InitialSyncer() {
DESTRUCTOR_GUARD({
shutdown().transitional_ignore();
join();
});
}
bool InitialSyncer::isActive() const {
stdx::lock_guard<stdx::mutex> lock(_mutex);
return _isActive_inlock();
}
bool InitialSyncer::_isActive_inlock() const {
return State::kRunning == _state || State::kShuttingDown == _state;
}
Status InitialSyncer::startup(OperationContext* opCtx,
std::uint32_t initialSyncMaxAttempts) noexcept {
invariant(opCtx);
invariant(initialSyncMaxAttempts >= 1U);
stdx::lock_guard<stdx::mutex> lock(_mutex);
switch (_state) {
case State::kPreStart:
_state = State::kRunning;
break;
case State::kRunning:
return Status(ErrorCodes::IllegalOperation, "initial syncer already started");
case State::kShuttingDown:
return Status(ErrorCodes::ShutdownInProgress, "initial syncer shutting down");
case State::kComplete:
return Status(ErrorCodes::ShutdownInProgress, "initial syncer completed");
}
_setUp_inlock(opCtx, initialSyncMaxAttempts);
// Start first initial sync attempt.
std::uint32_t initialSyncAttempt = 0;
auto status = _scheduleWorkAndSaveHandle_inlock(
stdx::bind(&InitialSyncer::_startInitialSyncAttemptCallback,
this,
stdx::placeholders::_1,
initialSyncAttempt,
initialSyncMaxAttempts),
&_startInitialSyncAttemptHandle,
str::stream() << "_startInitialSyncAttemptCallback-" << initialSyncAttempt);
if (!status.isOK()) {
_state = State::kComplete;
return status;
}
return Status::OK();
}
Status InitialSyncer::shutdown() {
stdx::lock_guard<stdx::mutex> lock(_mutex);
switch (_state) {
case State::kPreStart:
// Transition directly from PreStart to Complete if not started yet.
_state = State::kComplete;
return Status::OK();
case State::kRunning:
_state = State::kShuttingDown;
break;
case State::kShuttingDown:
case State::kComplete:
// Nothing to do if we are already in ShuttingDown or Complete state.
return Status::OK();
}
_cancelRemainingWork_inlock();
return Status::OK();
}
void InitialSyncer::_cancelRemainingWork_inlock() {
_cancelHandle_inlock(_startInitialSyncAttemptHandle);
_cancelHandle_inlock(_chooseSyncSourceHandle);
_cancelHandle_inlock(_getBaseRollbackIdHandle);
_cancelHandle_inlock(_getLastRollbackIdHandle);
_cancelHandle_inlock(_getNextApplierBatchHandle);
_shutdownComponent_inlock(_oplogFetcher);
if (_initialSyncState) {
_shutdownComponent_inlock(_initialSyncState->dbsCloner);
}
_shutdownComponent_inlock(_applier);
_shutdownComponent_inlock(_fCVFetcher);
_shutdownComponent_inlock(_lastOplogEntryFetcher);
}
void InitialSyncer::join() {
stdx::unique_lock<stdx::mutex> lk(_mutex);
_stateCondition.wait(lk, [this]() { return !_isActive_inlock(); });
}
InitialSyncer::State InitialSyncer::getState_forTest() const {
stdx::lock_guard<stdx::mutex> lk(_mutex);
return _state;
}
bool InitialSyncer::_isShuttingDown() const {
stdx::lock_guard<stdx::mutex> lock(_mutex);
return _isShuttingDown_inlock();
}
bool InitialSyncer::_isShuttingDown_inlock() const {
return State::kShuttingDown == _state;
}
std::string InitialSyncer::getDiagnosticString() const {
LockGuard lk(_mutex);
str::stream out;
out << "InitialSyncer -"
<< " opts: " << _opts.toString() << " oplogFetcher: " << _oplogFetcher->toString()
<< " opsBuffered: " << _oplogBuffer->getSize() << " active: " << _isActive_inlock()
<< " shutting down: " << _isShuttingDown_inlock();
if (_initialSyncState) {
out << " opsAppied: " << _initialSyncState->appliedOps;
}
return out;
}
BSONObj InitialSyncer::getInitialSyncProgress() const {
LockGuard lk(_mutex);
return _getInitialSyncProgress_inlock();
}
BSONObj InitialSyncer::_getInitialSyncProgress_inlock() const {
BSONObjBuilder bob;
try {
_stats.append(&bob);
if (_initialSyncState) {
bob.appendNumber("fetchedMissingDocs", _initialSyncState->fetchedMissingDocs);
bob.appendNumber("appliedOps", _initialSyncState->appliedOps);
if (!_initialSyncState->beginTimestamp.isNull()) {
bob.append("initialSyncOplogStart", _initialSyncState->beginTimestamp);
}
if (!_initialSyncState->stopTimestamp.isNull()) {
bob.append("initialSyncOplogEnd", _initialSyncState->stopTimestamp);
}
if (_initialSyncState->dbsCloner) {
BSONObjBuilder dbsBuilder(bob.subobjStart("databases"));
_initialSyncState->dbsCloner->getStats().append(&dbsBuilder);
dbsBuilder.doneFast();
}
}
} catch (const DBException& e) {
bob.resetToEmpty();
bob.append("error", e.toString());
log() << "Error creating initial sync progress object: " << e.toString();
}
return bob.obj();
}
void InitialSyncer::setScheduleDbWorkFn_forTest(const CollectionCloner::ScheduleDbWorkFn& work) {
LockGuard lk(_mutex);
_scheduleDbWorkFn = work;
}
void InitialSyncer::_setUp_inlock(OperationContext* opCtx, std::uint32_t initialSyncMaxAttempts) {
// 'opCtx' is passed through from startup().
_replicationProcess->getConsistencyMarkers()->setInitialSyncFlag(opCtx);
auto serviceCtx = opCtx->getServiceContext();
_storage->setInitialDataTimestamp(serviceCtx, Timestamp::kAllowUnstableCheckpointsSentinel);
_storage->setStableTimestamp(serviceCtx, Timestamp::min());
LOG(1) << "Creating oplogBuffer.";
_oplogBuffer = _dataReplicatorExternalState->makeInitialSyncOplogBuffer(opCtx);
_oplogBuffer->startup(opCtx);
_stats.initialSyncStart = _exec->now();
_stats.maxFailedInitialSyncAttempts = initialSyncMaxAttempts;
_stats.failedInitialSyncAttempts = 0;
}
void InitialSyncer::_tearDown_inlock(OperationContext* opCtx,
const StatusWith<OpTimeWithHash>& lastApplied) {
_stats.initialSyncEnd = _exec->now();
// This might not be necessary if we failed initial sync.
invariant(_oplogBuffer);
_oplogBuffer->shutdown(opCtx);
if (!lastApplied.isOK()) {
return;
}
// This is necessary to ensure that the oplog contains at least one visible document prior to
// setting an externally visible lastApplied. That way if any other node attempts to read from
// this node's oplog, it won't appear empty.
_storage->waitForAllEarlierOplogWritesToBeVisible(opCtx);
_storage->setInitialDataTimestamp(opCtx->getServiceContext(),
lastApplied.getValue().opTime.getTimestamp());
_replicationProcess->getConsistencyMarkers()->clearInitialSyncFlag(opCtx);
_opts.setMyLastOptime(lastApplied.getValue().opTime);
log() << "initial sync done; took "
<< duration_cast<Seconds>(_stats.initialSyncEnd - _stats.initialSyncStart) << ".";
initialSyncCompletes.increment();
}
void InitialSyncer::_startInitialSyncAttemptCallback(
const executor::TaskExecutor::CallbackArgs& callbackArgs,
std::uint32_t initialSyncAttempt,
std::uint32_t initialSyncMaxAttempts) {
auto status = _checkForShutdownAndConvertStatus_inlock(
callbackArgs,
str::stream() << "error while starting initial sync attempt " << (initialSyncAttempt + 1)
<< " of "
<< initialSyncMaxAttempts);
if (!status.isOK()) {
_finishInitialSyncAttempt(status);
return;
}
log() << "Starting initial sync (attempt " << (initialSyncAttempt + 1) << " of "
<< initialSyncMaxAttempts << ")";
// This completion guard invokes _finishInitialSyncAttempt on destruction.
auto cancelRemainingWorkInLock = [this]() { _cancelRemainingWork_inlock(); };
auto finishInitialSyncAttemptFn = [this](const StatusWith<OpTimeWithHash>& lastApplied) {
_finishInitialSyncAttempt(lastApplied);
};
auto onCompletionGuard =
std::make_shared<OnCompletionGuard>(cancelRemainingWorkInLock, finishInitialSyncAttemptFn);
// Lock guard must be declared after completion guard because completion guard destructor
// has to run outside lock.
stdx::lock_guard<stdx::mutex> lock(_mutex);
LOG(2) << "Resetting sync source so a new one can be chosen for this initial sync attempt.";
_syncSource = HostAndPort();
LOG(2) << "Resetting all optimes before starting this initial sync attempt.";
_opts.resetOptimes();
_lastApplied = {};
_lastFetched = {};
LOG(2) << "Resetting feature compatibility version to 3.4. If the sync source is in feature "
"compatibility version 3.6, we will find out when we clone the admin.system.version "
"collection.";
serverGlobalParams.featureCompatibility.reset();
// Clear the oplog buffer.
_oplogBuffer->clear(makeOpCtx().get());
// Get sync source.
std::uint32_t chooseSyncSourceAttempt = 0;
std::uint32_t chooseSyncSourceMaxAttempts =
static_cast<std::uint32_t>(numInitialSyncConnectAttempts.load());
// _scheduleWorkAndSaveHandle_inlock() is shutdown-aware.
status = _scheduleWorkAndSaveHandle_inlock(stdx::bind(&InitialSyncer::_chooseSyncSourceCallback,
this,
stdx::placeholders::_1,
chooseSyncSourceAttempt,
chooseSyncSourceMaxAttempts,
onCompletionGuard),
&_chooseSyncSourceHandle,
str::stream() << "_chooseSyncSourceCallback-"
<< chooseSyncSourceAttempt);
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
}
void InitialSyncer::_chooseSyncSourceCallback(
const executor::TaskExecutor::CallbackArgs& callbackArgs,
std::uint32_t chooseSyncSourceAttempt,
std::uint32_t chooseSyncSourceMaxAttempts,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
// Cancellation should be treated the same as other errors. In this case, the most likely cause
// of a failed _chooseSyncSourceCallback() task is a cancellation triggered by
// InitialSyncer::shutdown() or the task executor shutting down.
auto status =
_checkForShutdownAndConvertStatus_inlock(callbackArgs, "error while choosing sync source");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
if (MONGO_FAIL_POINT(failInitialSyncWithBadHost)) {
status = Status(ErrorCodes::InvalidSyncSource,
"no sync source avail(failInitialSyncWithBadHost failpoint is set).");
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
auto syncSource = _chooseSyncSource_inlock();
if (!syncSource.isOK()) {
if (chooseSyncSourceAttempt + 1 >= chooseSyncSourceMaxAttempts) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(
lock,
Status(ErrorCodes::InitialSyncOplogSourceMissing,
"No valid sync source found in current replica set to do an initial sync."));
return;
}
auto when = _exec->now() + _opts.syncSourceRetryWait;
LOG(1) << "Error getting sync source: '" << syncSource.getStatus() << "', trying again in "
<< _opts.syncSourceRetryWait << " at " << when.toString() << ". Attempt "
<< (chooseSyncSourceAttempt + 1) << " of " << numInitialSyncConnectAttempts.load();
auto status = _scheduleWorkAtAndSaveHandle_inlock(
when,
stdx::bind(&InitialSyncer::_chooseSyncSourceCallback,
this,
stdx::placeholders::_1,
chooseSyncSourceAttempt + 1,
chooseSyncSourceMaxAttempts,
onCompletionGuard),
&_chooseSyncSourceHandle,
str::stream() << "_chooseSyncSourceCallback-" << (chooseSyncSourceAttempt + 1));
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
return;
}
// There is no need to schedule separate task to create oplog collection since we are already in
// a callback and we are certain there's no existing operation context (required for creating
// collections and dropping user databases) attached to the current thread.
status = _truncateOplogAndDropReplicatedDatabases();
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
// Schedule rollback ID checker.
_syncSource = syncSource.getValue();
_rollbackChecker = stdx::make_unique<RollbackChecker>(_exec, _syncSource);
auto scheduleResult =
_rollbackChecker->reset(stdx::bind(&InitialSyncer::_rollbackCheckerResetCallback,
this,
stdx::placeholders::_1,
onCompletionGuard));
status = scheduleResult.getStatus();
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
_getBaseRollbackIdHandle = scheduleResult.getValue();
}
Status InitialSyncer::_truncateOplogAndDropReplicatedDatabases() {
// truncate oplog; drop user databases.
LOG(1) << "About to truncate the oplog, if it exists, ns:" << _opts.localOplogNS
<< ", and drop all user databases (so that we can clone them).";
auto opCtx = makeOpCtx();
// We are not replicating nor validating these writes.
UnreplicatedWritesBlock unreplicatedWritesBlock(opCtx.get());
// 1.) Truncate the oplog.
LOG(2) << "Truncating the existing oplog: " << _opts.localOplogNS;
auto status = _storage->truncateCollection(opCtx.get(), _opts.localOplogNS);
if (!status.isOK()) {
// 1a.) Create the oplog.
LOG(2) << "Creating the oplog: " << _opts.localOplogNS;
status = _storage->createOplog(opCtx.get(), _opts.localOplogNS);
if (!status.isOK()) {
return status;
}
}
// 2.) Drop user databases.
LOG(2) << "Dropping user databases";
return _storage->dropReplicatedDatabases(opCtx.get());
}
void InitialSyncer::_rollbackCheckerResetCallback(
const RollbackChecker::Result& result, std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
auto status = _checkForShutdownAndConvertStatus_inlock(result.getStatus(),
"error while getting base rollback ID");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
status = _scheduleLastOplogEntryFetcher_inlock(
stdx::bind(&InitialSyncer::_lastOplogEntryFetcherCallbackForBeginTimestamp,
this,
stdx::placeholders::_1,
onCompletionGuard));
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
}
void InitialSyncer::_lastOplogEntryFetcherCallbackForBeginTimestamp(
const StatusWith<Fetcher::QueryResponse>& result,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
stdx::unique_lock<stdx::mutex> lock(_mutex);
auto status = _checkForShutdownAndConvertStatus_inlock(
result.getStatus(), "error while getting last oplog entry for begin timestamp");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
const auto opTimeWithHashResult = parseOpTimeWithHash(result);
status = opTimeWithHashResult.getStatus();
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
const auto& lastOpTimeWithHash = opTimeWithHashResult.getValue();
BSONObjBuilder queryBob;
queryBob.append("find", nsToCollectionSubstring(FeatureCompatibilityVersion::kCollection));
auto filterBob = BSONObjBuilder(queryBob.subobjStart("filter"));
filterBob.append("_id", FeatureCompatibilityVersion::kParameterName);
filterBob.done();
_fCVFetcher = stdx::make_unique<Fetcher>(
_exec,
_syncSource,
nsToDatabaseSubstring(FeatureCompatibilityVersion::kCollection).toString(),
queryBob.obj(),
stdx::bind(&InitialSyncer::_fcvFetcherCallback,
this,
stdx::placeholders::_1,
onCompletionGuard,
lastOpTimeWithHash),
ReadPreferenceSetting::secondaryPreferredMetadata(),
RemoteCommandRequest::kNoTimeout /* find network timeout */,
RemoteCommandRequest::kNoTimeout /* getMore network timeout */,
RemoteCommandRetryScheduler::makeRetryPolicy(
numInitialSyncOplogFindAttempts.load(),
executor::RemoteCommandRequest::kNoTimeout,
RemoteCommandRetryScheduler::kAllRetriableErrors));
Status scheduleStatus = _fCVFetcher->schedule();
if (!scheduleStatus.isOK()) {
_fCVFetcher.reset();
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, scheduleStatus);
return;
}
}
void InitialSyncer::_fcvFetcherCallback(const StatusWith<Fetcher::QueryResponse>& result,
std::shared_ptr<OnCompletionGuard> onCompletionGuard,
const OpTimeWithHash& lastOpTimeWithHash) {
stdx::unique_lock<stdx::mutex> lock(_mutex);
auto status = _checkForShutdownAndConvertStatus_inlock(
result.getStatus(), "error while getting the remote feature compatibility version");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
const auto docs = result.getValue().documents;
if (docs.size() > 1) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(
lock,
Status(ErrorCodes::TooManyMatchingDocuments,
str::stream() << "Expected to receive one document, but received: "
<< docs.size()
<< ". First: "
<< redact(docs.front())
<< ". Last: "
<< redact(docs.back())));
return;
}
const auto hasDoc = docs.begin() != docs.end();
if (!hasDoc) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(
lock,
Status(ErrorCodes::IncompatibleServerVersion,
"Sync source had no feature compatibility version document"));
return;
}
auto fCVParseSW = FeatureCompatibilityVersion::parse(docs.front());
if (!fCVParseSW.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, fCVParseSW.getStatus());
return;
}
auto version = fCVParseSW.getValue();
if (version != ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo34 &&
version != ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo36) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(
lock,
Status(ErrorCodes::IncompatibleServerVersion,
str::stream() << "Sync source had unsafe feature compatibility version: "
<< FeatureCompatibilityVersion::toString(version)));
return;
}
// This is where the flow of control starts to split into two parallel tracks:
// - oplog fetcher
// - data cloning and applier
auto listDatabasesFilter = [](BSONObj dbInfo) {
std::string name;
auto status = mongo::bsonExtractStringField(dbInfo, "name", &name);
if (!status.isOK()) {
error() << "listDatabases filter failed to parse database name from " << redact(dbInfo)
<< ": " << redact(status);
return false;
}
return (name != "local");
};
_initialSyncState = stdx::make_unique<InitialSyncState>(
stdx::make_unique<DatabasesCloner>(_storage,
_exec,
_dataReplicatorExternalState->getDbWorkThreadPool(),
_syncSource,
listDatabasesFilter,
stdx::bind(&InitialSyncer::_databasesClonerCallback,
this,
stdx::placeholders::_1,
onCompletionGuard)));
_initialSyncState->beginTimestamp = lastOpTimeWithHash.opTime.getTimestamp();
invariant(!result.getValue().documents.empty());
LOG(2) << "Setting begin timestamp to " << _initialSyncState->beginTimestamp
<< " using last oplog entry: " << redact(result.getValue().documents.front())
<< ", ns: " << _opts.localOplogNS;
const auto configResult = _dataReplicatorExternalState->getCurrentConfig();
status = configResult.getStatus();
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
_initialSyncState.reset();
return;
}
const auto& config = configResult.getValue();
_oplogFetcher = stdx::make_unique<OplogFetcher>(
_exec,
lastOpTimeWithHash,
_syncSource,
_opts.remoteOplogNS,
config,
_opts.oplogFetcherMaxFetcherRestarts,
_rollbackChecker->getBaseRBID(),
false /* requireFresherSyncSource */,
_dataReplicatorExternalState.get(),
stdx::bind(&InitialSyncer::_enqueueDocuments,
this,
stdx::placeholders::_1,
stdx::placeholders::_2,
stdx::placeholders::_3),
stdx::bind(
&InitialSyncer::_oplogFetcherCallback, this, stdx::placeholders::_1, onCompletionGuard),
initialSyncOplogFetcherBatchSize);
LOG(2) << "Starting OplogFetcher: " << _oplogFetcher->toString();
// _startupComponent_inlock is shutdown-aware.
status = _startupComponent_inlock(_oplogFetcher);
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
_initialSyncState->dbsCloner.reset();
return;
}
if (MONGO_FAIL_POINT(initialSyncHangBeforeCopyingDatabases)) {
lock.unlock();
// This could have been done with a scheduleWorkAt but this is used only by JS tests where
// we run with multiple threads so it's fine to spin on this thread.
// This log output is used in js tests so please leave it.
log() << "initial sync - initialSyncHangBeforeCopyingDatabases fail point "
"enabled. Blocking until fail point is disabled.";
while (MONGO_FAIL_POINT(initialSyncHangBeforeCopyingDatabases) && !_isShuttingDown()) {
mongo::sleepsecs(1);
}
lock.lock();
}
if (_scheduleDbWorkFn) {
// '_scheduleDbWorkFn' is passed through (DatabasesCloner->DatabaseCloner->CollectionCloner)
// to the CollectionCloner so that CollectionCloner's default TaskRunner can be disabled to
// facilitate testing.
_initialSyncState->dbsCloner->setScheduleDbWorkFn_forTest(_scheduleDbWorkFn);
}
LOG(2) << "Starting DatabasesCloner: " << _initialSyncState->dbsCloner->toString();
// _startupComponent_inlock() is shutdown-aware. Additionally, if the component fails to
// startup, _startupComponent_inlock() resets the unique_ptr to the component (in this case,
// DatabasesCloner).
status = _startupComponent_inlock(_initialSyncState->dbsCloner);
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
}
void InitialSyncer::_oplogFetcherCallback(const Status& oplogFetcherFinishStatus,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
log() << "Finished fetching oplog during initial sync: " << redact(oplogFetcherFinishStatus)
<< ". Last fetched optime and hash: " << _lastFetched.toString();
auto status = _checkForShutdownAndConvertStatus_inlock(
oplogFetcherFinishStatus, "error fetching oplog during initial sync");
// When the OplogFetcher completes early (instead of being canceled at shutdown), we log and let
// our reference to 'onCompletionGuard' go out of scope. Since we know the
// DatabasesCloner/MultiApplier will still have a reference to it, the actual function within
// the guard won't be fired yet.
// It is up to the DatabasesCloner and MultiApplier to determine if they can proceed without any
// additional data going into the oplog buffer.
// It is not common for the OplogFetcher to return with an OK status. The only time it returns
// an OK status is when the 'stopReplProducer' fail point is enabled, which causes the
// OplogFetcher to ignore the current sync source response and return early.
if (status.isOK()) {
log() << "Finished fetching oplog fetching early. Last fetched optime and hash: "
<< _lastFetched.toString();
return;
}
// During normal operation, this call to onCompletion->setResultAndCancelRemainingWork_inlock
// is a no-op because the other thread running the DatabasesCloner or MultiApplier will already
// have called it with the success/failed status.
// The OplogFetcher does not finish on its own because of the oplog tailing query it runs on the
// sync source. The most common OplogFetcher completion status is CallbackCanceled due to either
// a shutdown request or completion of the data cloning and oplog application phases.
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
}
void InitialSyncer::_databasesClonerCallback(const Status& databaseClonerFinishStatus,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
log() << "Finished cloning data: " << redact(databaseClonerFinishStatus)
<< ". Beginning oplog replay.";
stdx::lock_guard<stdx::mutex> lock(_mutex);
auto status = _checkForShutdownAndConvertStatus_inlock(databaseClonerFinishStatus,
"error cloning databases");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
status = _scheduleLastOplogEntryFetcher_inlock(
stdx::bind(&InitialSyncer::_lastOplogEntryFetcherCallbackForStopTimestamp,
this,
stdx::placeholders::_1,
onCompletionGuard));
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
}
void InitialSyncer::_lastOplogEntryFetcherCallbackForStopTimestamp(
const StatusWith<Fetcher::QueryResponse>& result,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
OpTimeWithHash optimeWithHash;
{
stdx::lock_guard<stdx::mutex> lock(_mutex);
auto status = _checkForShutdownAndConvertStatus_inlock(
result.getStatus(), "error fetching last oplog entry for stop timestamp");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
auto&& optimeWithHashStatus = parseOpTimeWithHash(result);
if (!optimeWithHashStatus.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(
lock, optimeWithHashStatus.getStatus());
return;
}
optimeWithHash = optimeWithHashStatus.getValue();
_initialSyncState->stopTimestamp = optimeWithHash.opTime.getTimestamp();
if (_initialSyncState->beginTimestamp != _initialSyncState->stopTimestamp) {
invariant(_lastApplied.opTime.isNull());
_checkApplierProgressAndScheduleGetNextApplierBatch_inlock(lock, onCompletionGuard);
return;
}
}
// Oplog at sync source has not advanced since we started cloning databases, so we use the last
// oplog entry to seed the oplog before checking the rollback ID.
{
const auto& documents = result.getValue().documents;
invariant(!documents.empty());
const BSONObj oplogSeedDoc = documents.front();
LOG(2) << "Inserting oplog seed document: " << oplogSeedDoc;
auto opCtx = makeOpCtx();
// StorageInterface::insertDocument() has to be called outside the lock because we may
// override its behavior in tests. See InitialSyncerReturnsCallbackCanceledAndDoesNot-
// ScheduleRollbackCheckerIfShutdownAfterInsertingInsertOplogSeedDocument in
// initial_syncer_test.cpp
auto status = _storage->insertDocument(
opCtx.get(),
_opts.localOplogNS,
TimestampedBSONObj{oplogSeedDoc, optimeWithHash.opTime.getTimestamp()},
optimeWithHash.opTime.getTerm());
if (!status.isOK()) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
}
stdx::lock_guard<stdx::mutex> lock(_mutex);
_lastApplied = optimeWithHash;
log() << "No need to apply operations. (currently at "
<< _initialSyncState->stopTimestamp.toBSON() << ")";
// This sets the error in 'onCompletionGuard' and shuts down the OplogFetcher on error.
_scheduleRollbackCheckerCheckForRollback_inlock(lock, onCompletionGuard);
}
void InitialSyncer::_getNextApplierBatchCallback(
const executor::TaskExecutor::CallbackArgs& callbackArgs,
std::shared_ptr<OnCompletionGuard> onCompletionGuard) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
auto status =
_checkForShutdownAndConvertStatus_inlock(callbackArgs, "error getting next applier batch");
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
auto batchResult = _getNextApplierBatch_inlock();
if (!batchResult.isOK()) {
warning() << "Failure creating next apply batch: " << redact(batchResult.getStatus());
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, batchResult.getStatus());
return;
}
// Schedule MultiApplier if we have operations to apply.
const auto& ops = batchResult.getValue();
if (!ops.empty()) {
_fetchCount.store(0);
// "_syncSource" has to be copied to stdx::bind result.
HostAndPort source = _syncSource;
auto applyOperationsForEachReplicationWorkerThreadFn =
stdx::bind(&DataReplicatorExternalState::_multiInitialSyncApply,
_dataReplicatorExternalState.get(),
stdx::placeholders::_1,
source,
&_fetchCount);
auto applyBatchOfOperationsFn = stdx::bind(&DataReplicatorExternalState::_multiApply,
_dataReplicatorExternalState.get(),
stdx::placeholders::_1,
stdx::placeholders::_2,
stdx::placeholders::_3);
const auto lastEntry = ops.back().raw;
const auto opTimeWithHashStatus = AbstractOplogFetcher::parseOpTimeWithHash(lastEntry);
status = opTimeWithHashStatus.getStatus();
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
auto lastApplied = opTimeWithHashStatus.getValue();
auto numApplied = ops.size();
_applier = stdx::make_unique<MultiApplier>(_exec,
ops,
applyOperationsForEachReplicationWorkerThreadFn,
applyBatchOfOperationsFn,
stdx::bind(&InitialSyncer::_multiApplierCallback,
this,
stdx::placeholders::_1,
lastApplied,
numApplied,
onCompletionGuard));
status = _startupComponent_inlock(_applier);
if (!status.isOK()) {
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
return;
}
// If the oplog fetcher is no longer running (completed successfully) and the oplog buffer is
// empty, we are not going to make any more progress with this initial sync. Report progress so
// far and return a RemoteResultsUnavailable error.
if (!_oplogFetcher->isActive()) {
std::string msg = str::stream()
<< "The oplog fetcher is no longer running and we have applied all the oplog entries "
"in the oplog buffer. Aborting this initial sync attempt. Last applied: "
<< _lastApplied.toString() << ". Last fetched: " << _lastFetched.toString()
<< ". Number of operations applied: " << _initialSyncState->appliedOps;
log() << msg;
status = Status(ErrorCodes::RemoteResultsUnavailable, msg);
onCompletionGuard->setResultAndCancelRemainingWork_inlock(lock, status);
return;
}
// If there are no operations at the moment to apply and the oplog fetcher is still waiting on
// the sync source, we'll check the oplog buffer again in
// '_opts.getApplierBatchCallbackRetryWait' ms.
auto when = _exec->now() + _opts.getApplierBatchCallbackRetryWait;
status =
_scheduleWorkAtAndSaveHandle_inlock(when,
stdx::bind(&InitialSyncer::_getNextApplierBatchCallback,
this,
stdx::placeholders::_1,
onCompletionGuard),