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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::kSharding
#include "mongo/platform/basic.h"
#include "mongo/db/s/migration_destination_manager.h"
#include <list>
#include <vector>
#include "mongo/client/connpool.h"
#include "mongo/db/auth/authorization_manager_global.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/document_validation.h"
#include "mongo/db/catalog/index_create.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/dbhelpers.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/ops/delete.h"
#include "mongo/db/repl/repl_client_info.h"
#include "mongo/db/repl/replication_coordinator_global.h"
#include "mongo/db/s/collection_metadata.h"
#include "mongo/db/s/collection_range_deleter.h"
#include "mongo/db/s/collection_sharding_state.h"
#include "mongo/db/s/migration_util.h"
#include "mongo/db/s/move_timing_helper.h"
#include "mongo/db/s/sharding_state.h"
#include "mongo/db/service_context.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/shard_key_pattern.h"
#include "mongo/stdx/chrono.h"
#include "mongo/util/concurrency/notification.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
using std::string;
using str::stream;
namespace {
const WriteConcernOptions kMajorityWriteConcern(WriteConcernOptions::kMajority,
// Note: Even though we're setting UNSET here,
// kMajority implies JOURNAL if journaling is
// supported by mongod and
// writeConcernMajorityJournalDefault is set to true
// in the ReplSetConfig.
WriteConcernOptions::SyncMode::UNSET,
-1);
/**
* Returns a human-readabale name of the migration manager's state.
*/
string stateToString(MigrationDestinationManager::State state) {
switch (state) {
case MigrationDestinationManager::READY:
return "ready";
case MigrationDestinationManager::CLONE:
return "clone";
case MigrationDestinationManager::CATCHUP:
return "catchup";
case MigrationDestinationManager::STEADY:
return "steady";
case MigrationDestinationManager::COMMIT_START:
return "commitStart";
case MigrationDestinationManager::DONE:
return "done";
case MigrationDestinationManager::FAIL:
return "fail";
case MigrationDestinationManager::ABORT:
return "abort";
default:
MONGO_UNREACHABLE;
}
}
bool isInRange(const BSONObj& obj,
const BSONObj& min,
const BSONObj& max,
const BSONObj& shardKeyPattern) {
ShardKeyPattern shardKey(shardKeyPattern);
BSONObj k = shardKey.extractShardKeyFromDoc(obj);
return k.woCompare(min) >= 0 && k.woCompare(max) < 0;
}
/**
* Checks if an upsert of a remote document will override a local document with the same _id but in
* a different range on this shard. Must be in WriteContext to avoid races and DBHelper errors.
*
* TODO: Could optimize this check out if sharding on _id.
*/
bool willOverrideLocalId(OperationContext* opCtx,
const NamespaceString& nss,
BSONObj min,
BSONObj max,
BSONObj shardKeyPattern,
Database* db,
BSONObj remoteDoc,
BSONObj* localDoc) {
*localDoc = BSONObj();
if (Helpers::findById(opCtx, db, nss.ns(), remoteDoc, *localDoc)) {
return !isInRange(*localDoc, min, max, shardKeyPattern);
}
return false;
}
/**
* Returns true if the majority of the nodes and the nodes corresponding to the given writeConcern
* (if not empty) have applied till the specified lastOp.
*/
bool opReplicatedEnough(OperationContext* opCtx,
const repl::OpTime& lastOpApplied,
const WriteConcernOptions& writeConcern) {
WriteConcernResult writeConcernResult;
writeConcernResult.wTimedOut = false;
Status majorityStatus =
waitForWriteConcern(opCtx, lastOpApplied, kMajorityWriteConcern, &writeConcernResult);
if (!majorityStatus.isOK()) {
if (!writeConcernResult.wTimedOut) {
uassertStatusOK(majorityStatus);
}
return false;
}
// Enforce the user specified write concern after "majority" so it covers the union of the 2
// write concerns in case the user's write concern is stronger than majority
WriteConcernOptions userWriteConcern(writeConcern);
userWriteConcern.wTimeout = -1;
writeConcernResult.wTimedOut = false;
Status userStatus =
waitForWriteConcern(opCtx, lastOpApplied, userWriteConcern, &writeConcernResult);
if (!userStatus.isOK()) {
if (!writeConcernResult.wTimedOut) {
uassertStatusOK(userStatus);
}
return false;
}
return true;
}
/**
* Create the migration clone request BSON object to send to the source shard.
*
* 'sessionId' unique identifier for this migration.
*/
BSONObj createMigrateCloneRequest(const NamespaceString& nss, const MigrationSessionId& sessionId) {
BSONObjBuilder builder;
builder.append("_migrateClone", nss.ns());
sessionId.append(&builder);
return builder.obj();
}
/**
* Create the migration transfer mods request BSON object to send to the source shard.
*
* 'sessionId' unique identifier for this migration.
*/
BSONObj createTransferModsRequest(const NamespaceString& nss, const MigrationSessionId& sessionId) {
BSONObjBuilder builder;
builder.append("_transferMods", nss.ns());
sessionId.append(&builder);
return builder.obj();
}
// Enabling / disabling these fail points pauses / resumes MigrateStatus::_go(), the thread which
// receives a chunk migration from the donor.
MONGO_FP_DECLARE(migrateThreadHangAtStep1);
MONGO_FP_DECLARE(migrateThreadHangAtStep2);
MONGO_FP_DECLARE(migrateThreadHangAtStep3);
MONGO_FP_DECLARE(migrateThreadHangAtStep4);
MONGO_FP_DECLARE(migrateThreadHangAtStep5);
MONGO_FP_DECLARE(migrateThreadHangAtStep6);
MONGO_FP_DECLARE(failMigrationReceivedOutOfRangeOperation);
} // namespace
MigrationDestinationManager::MigrationDestinationManager() = default;
MigrationDestinationManager::~MigrationDestinationManager() = default;
MigrationDestinationManager::State MigrationDestinationManager::getState() const {
stdx::lock_guard<stdx::mutex> sl(_mutex);
return _state;
}
void MigrationDestinationManager::setState(State newState) {
stdx::lock_guard<stdx::mutex> sl(_mutex);
_state = newState;
}
void MigrationDestinationManager::setStateFail(std::string msg) {
log() << msg;
{
stdx::lock_guard<stdx::mutex> sl(_mutex);
_errmsg = std::move(msg);
_state = FAIL;
}
_sessionMigration->forceFail(msg);
}
void MigrationDestinationManager::setStateFailWarn(std::string msg) {
warning() << msg;
{
stdx::lock_guard<stdx::mutex> sl(_mutex);
_errmsg = std::move(msg);
_state = FAIL;
}
_sessionMigration->forceFail(msg);
}
bool MigrationDestinationManager::isActive() const {
stdx::lock_guard<stdx::mutex> lk(_mutex);
return _isActive(lk);
}
bool MigrationDestinationManager::_isActive(WithLock) const {
return _sessionId.is_initialized();
}
void MigrationDestinationManager::report(BSONObjBuilder& b) {
stdx::lock_guard<stdx::mutex> sl(_mutex);
b.appendBool("active", _sessionId.is_initialized());
if (_sessionId) {
b.append("sessionId", _sessionId->toString());
}
b.append("ns", _nss.ns());
b.append("from", _fromShardConnString.toString());
b.append("min", _min);
b.append("max", _max);
b.append("shardKeyPattern", _shardKeyPattern);
b.append("state", stateToString(_state));
if (_state == FAIL) {
invariant(!_errmsg.empty());
b.append("errmsg", _errmsg);
}
BSONObjBuilder bb(b.subobjStart("counts"));
bb.append("cloned", _numCloned);
bb.append("clonedBytes", _clonedBytes);
bb.append("catchup", _numCatchup);
bb.append("steady", _numSteady);
bb.done();
}
BSONObj MigrationDestinationManager::getMigrationStatusReport() {
stdx::lock_guard<stdx::mutex> lk(_mutex);
if (_isActive(lk)) {
return migrationutil::makeMigrationStatusDocument(
_nss, _fromShard, _toShard, false, _min, _max);
} else {
return BSONObj();
}
}
Status MigrationDestinationManager::start(const NamespaceString& nss,
ScopedRegisterReceiveChunk scopedRegisterReceiveChunk,
const MigrationSessionId& sessionId,
const ConnectionString& fromShardConnString,
const ShardId& fromShard,
const ShardId& toShard,
const BSONObj& min,
const BSONObj& max,
const BSONObj& shardKeyPattern,
const OID& epoch,
const WriteConcernOptions& writeConcern) {
stdx::lock_guard<stdx::mutex> lk(_mutex);
invariant(!_sessionId);
invariant(!_scopedRegisterReceiveChunk);
_state = READY;
_errmsg = "";
_nss = nss;
_fromShardConnString = fromShardConnString;
_fromShard = fromShard;
_toShard = toShard;
_min = min;
_max = max;
_shardKeyPattern = shardKeyPattern;
_chunkMarkedPending = false;
_numCloned = 0;
_clonedBytes = 0;
_numCatchup = 0;
_numSteady = 0;
_sessionId = sessionId;
_scopedRegisterReceiveChunk = std::move(scopedRegisterReceiveChunk);
// TODO: If we are here, the migrate thread must have completed, otherwise _active above
// would be false, so this would never block. There is no better place with the current
// implementation where to join the thread.
if (_migrateThreadHandle.joinable()) {
_migrateThreadHandle.join();
}
_sessionMigration =
stdx::make_unique<SessionCatalogMigrationDestination>(fromShard, *_sessionId);
_migrateThreadHandle =
stdx::thread([this, min, max, shardKeyPattern, fromShardConnString, epoch, writeConcern]() {
_migrateThread(min, max, shardKeyPattern, fromShardConnString, epoch, writeConcern);
});
return Status::OK();
}
Status MigrationDestinationManager::abort(const MigrationSessionId& sessionId) {
stdx::lock_guard<stdx::mutex> sl(_mutex);
if (!_sessionId) {
return Status::OK();
}
if (!_sessionId->matches(sessionId)) {
return {ErrorCodes::CommandFailed,
str::stream() << "received abort request from a stale session "
<< sessionId.toString()
<< ". Current session is "
<< _sessionId->toString()};
}
_state = ABORT;
_errmsg = "aborted";
return Status::OK();
}
void MigrationDestinationManager::abortWithoutSessionIdCheck() {
stdx::lock_guard<stdx::mutex> sl(_mutex);
_state = ABORT;
_errmsg = "aborted without session id check";
}
Status MigrationDestinationManager::startCommit(const MigrationSessionId& sessionId) {
stdx::unique_lock<stdx::mutex> lock(_mutex);
if (_state != STEADY) {
return {ErrorCodes::CommandFailed,
str::stream() << "Migration startCommit attempted when not in STEADY state."
<< " Sender's session is "
<< sessionId.toString()
<< (_sessionId ? (". Current session is " + _sessionId->toString())
: ". No active session on this shard.")};
}
// In STEADY state we must have active migration
invariant(_sessionId);
// This check guards against the (unusual) situation where the current donor shard has stalled,
// during which the recipient shard crashed or timed out, and then began serving as a recipient
// or donor for another migration.
if (!_sessionId->matches(sessionId)) {
return {ErrorCodes::CommandFailed,
str::stream() << "startCommit received commit request from a stale session "
<< sessionId.toString()
<< ". Current session is "
<< _sessionId->toString()};
}
_sessionMigration->finish();
_state = COMMIT_START;
auto const deadline = Date_t::now() + Seconds(30);
while (_sessionId) {
if (stdx::cv_status::timeout ==
_isActiveCV.wait_until(lock, deadline.toSystemTimePoint())) {
_errmsg = str::stream() << "startCommit timed out waiting, " << _sessionId->toString();
_state = FAIL;
return {ErrorCodes::CommandFailed, _errmsg};
}
}
if (_state != DONE) {
return {ErrorCodes::CommandFailed, "startCommit failed, final data failed to transfer"};
}
return Status::OK();
}
void MigrationDestinationManager::_migrateThread(BSONObj min,
BSONObj max,
BSONObj shardKeyPattern,
ConnectionString fromShardConnString,
OID epoch,
WriteConcernOptions writeConcern) {
Client::initThread("migrateThread");
auto opCtx = getGlobalServiceContext()->makeOperationContext(&cc());
if (getGlobalAuthorizationManager()->isAuthEnabled()) {
AuthorizationSession::get(opCtx->getClient())->grantInternalAuthorization();
}
try {
_migrateDriver(
opCtx.get(), min, max, shardKeyPattern, fromShardConnString, epoch, writeConcern);
} catch (std::exception& e) {
setStateFail(str::stream() << "migrate failed: " << redact(e.what()));
} catch (...) {
setStateFail("migrate failed with unknown exception: UNKNOWN ERROR");
}
if (getState() != DONE) {
_forgetPending(opCtx.get(), _nss, epoch, ChunkRange(min, max));
}
stdx::lock_guard<stdx::mutex> lk(_mutex);
_sessionId.reset();
_scopedRegisterReceiveChunk.reset();
_isActiveCV.notify_all();
}
void MigrationDestinationManager::_migrateDriver(OperationContext* opCtx,
const BSONObj& min,
const BSONObj& max,
const BSONObj& shardKeyPattern,
const ConnectionString& fromShardConnString,
const OID& epoch,
const WriteConcernOptions& writeConcern) {
invariant(isActive());
invariant(_sessionId);
invariant(_scopedRegisterReceiveChunk);
invariant(!min.isEmpty());
invariant(!max.isEmpty());
log() << "Starting receiving end of migration of chunk " << redact(min) << " -> " << redact(max)
<< " for collection " << _nss.ns() << " from " << fromShardConnString << " at epoch "
<< epoch.toString() << " with session id " << *_sessionId;
MoveTimingHelper timing(
opCtx, "to", _nss.ns(), min, max, 6 /* steps */, &_errmsg, ShardId(), ShardId());
const auto initialState = getState();
if (initialState == ABORT) {
error() << "Migration abort requested before it started";
return;
}
invariant(initialState == READY);
ScopedDbConnection conn(fromShardConnString);
// Just tests the connection
conn->getLastError();
DisableDocumentValidation validationDisabler(opCtx);
std::vector<BSONObj> indexSpecs;
BSONObj idIndexSpec;
{
auto indexes = conn->getIndexSpecs(_nss.ns());
for (auto&& spec : indexes) {
indexSpecs.push_back(spec);
if (auto indexNameElem = spec[IndexDescriptor::kIndexNameFieldName]) {
if (indexNameElem.type() == BSONType::String &&
indexNameElem.valueStringData() == "_id_"_sd) {
idIndexSpec = spec;
}
}
}
}
{
// 0. copy system.namespaces entry if collection doesn't already exist
OldClientWriteContext ctx(opCtx, _nss.ns());
if (!repl::getGlobalReplicationCoordinator()->canAcceptWritesFor(opCtx, _nss)) {
setStateFailWarn(str::stream() << "Not primary during migration: " << _nss.ns()
<< ": checking if collection exists");
return;
}
// Only copy if ns doesn't already exist
Database* const db = ctx.db();
Collection* const collection = db->getCollection(opCtx, _nss);
if (!collection) {
std::list<BSONObj> infos =
conn->getCollectionInfos(_nss.db().toString(), BSON("name" << _nss.coll()));
if (infos.size() != 1) {
setStateFailWarn(str::stream()
<< "expected listCollections against the donor shard for "
<< _nss.ns()
<< " to return 1 entry, but got "
<< infos.size()
<< " entries");
return;
}
BSONObj entry = infos.front();
BSONObj options;
BSONObj optionsWithoutUUID;
if (entry["options"].isABSONObj()) {
optionsWithoutUUID = entry["options"].Obj();
}
BSONObj info;
if (entry["info"].isABSONObj()) {
info = entry["info"].Obj();
}
// If in featureCompatibilityVersion >= 3.6, require the donor to return the
// collection's UUID.
if (serverGlobalParams.featureCompatibility.version.load() >=
ServerGlobalParams::FeatureCompatibility::Version::k36) {
if (info["uuid"].eoo()) {
setStateFailWarn(str::stream()
<< "The donor shard did not return a UUID for collection "
<< _nss.ns()
<< " as part of its listCollections response: "
<< entry
<< ", but this node expects to see a UUID since its "
"feature compatibility version is 3.6. Please follow "
"the online documentation to set the same feature "
"compatibility version across the cluster.");
return;
}
BSONObjBuilder optionsBob;
optionsBob.appendElements(optionsWithoutUUID);
optionsBob.append(info["uuid"]);
options = optionsBob.obj();
} else {
options = optionsWithoutUUID.getOwned();
}
WriteUnitOfWork wuow(opCtx);
const bool createDefaultIndexes = true;
Status status = userCreateNS(opCtx,
db,
_nss.ns(),
options,
CollectionOptions::parseForStorage,
createDefaultIndexes,
idIndexSpec);
if (!status.isOK()) {
warning() << "failed to create collection [" << _nss << "] "
<< " with options " << options << ": " << redact(status);
}
wuow.commit();
}
}
{
// 1. copy indexes
Lock::DBLock lk(opCtx, _nss.db(), MODE_X);
OldClientContext ctx(opCtx, _nss.ns());
if (!repl::getGlobalReplicationCoordinator()->canAcceptWritesFor(opCtx, _nss)) {
setStateFailWarn(str::stream() << "Not primary during migration: " << _nss.ns());
return;
}
Database* db = ctx.db();
Collection* collection = db->getCollection(opCtx, _nss);
if (!collection) {
setStateFailWarn(str::stream() << "collection dropped during migration: " << _nss.ns());
return;
}
MultiIndexBlock indexer(opCtx, collection);
indexer.removeExistingIndexes(&indexSpecs);
if (!indexSpecs.empty()) {
// Only copy indexes if the collection does not have any documents.
if (collection->numRecords(opCtx) > 0) {
setStateFailWarn(str::stream() << "aborting migration, shard is missing "
<< indexSpecs.size()
<< " indexes and "
<< "collection is not empty. Non-trivial "
<< "index creation should be scheduled manually");
return;
}
auto indexInfoObjs = indexer.init(indexSpecs);
if (!indexInfoObjs.isOK()) {
setStateFailWarn(str::stream() << "failed to create index before migrating data. "
<< " error: "
<< redact(indexInfoObjs.getStatus()));
return;
}
auto status = indexer.insertAllDocumentsInCollection();
if (!status.isOK()) {
setStateFailWarn(str::stream() << "failed to create index before migrating data. "
<< " error: "
<< redact(status));
return;
}
WriteUnitOfWork wunit(opCtx);
indexer.commit();
for (auto&& infoObj : indexInfoObjs.getValue()) {
// make sure to create index on secondaries as well
getGlobalServiceContext()->getOpObserver()->onCreateIndex(
opCtx, collection->ns(), collection->uuid(), infoObj, true /* fromMigrate */);
}
wunit.commit();
}
timing.done(1);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep1);
}
{
// 2. Synchronously delete any data which might have been left orphaned in the range
// being moved, and wait for completion
auto footprint = ChunkRange(min, max);
auto notification = _notePending(opCtx, _nss, epoch, footprint);
// wait for the range deletion to report back
if (!notification.waitStatus(opCtx).isOK()) {
setStateFail(notification.waitStatus(opCtx).reason());
return;
}
// wait for any other, overlapping queued deletions to drain
auto status = CollectionShardingState::waitForClean(opCtx, _nss, epoch, footprint);
if (!status.isOK()) {
setStateFail(status.reason());
return;
}
timing.done(2);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep2);
}
{
// 3. Initial bulk clone
setState(CLONE);
_sessionMigration->start(opCtx->getServiceContext());
const BSONObj migrateCloneRequest = createMigrateCloneRequest(_nss, *_sessionId);
_chunkMarkedPending = true; // no lock needed, only the migrate thread looks.
while (true) {
BSONObj res;
if (!conn->runCommand("admin",
migrateCloneRequest,
res)) { // gets array of objects to copy, in disk order
setStateFail(str::stream() << "_migrateClone failed: " << redact(res.toString()));
conn.done();
return;
}
BSONObj arr = res["objects"].Obj();
int thisTime = 0;
BSONObjIterator i(arr);
while (i.more()) {
opCtx->checkForInterrupt();
if (getState() == ABORT) {
log() << "Migration aborted while copying documents";
return;
}
BSONObj docToClone = i.next().Obj();
{
OldClientWriteContext cx(opCtx, _nss.ns());
BSONObj localDoc;
if (willOverrideLocalId(opCtx,
_nss,
min,
max,
shardKeyPattern,
cx.db(),
docToClone,
&localDoc)) {
string errMsg = str::stream() << "cannot migrate chunk, local document "
<< redact(localDoc)
<< " has same _id as cloned "
<< "remote document " << redact(docToClone);
warning() << errMsg;
// Exception will abort migration cleanly
uasserted(16976, errMsg);
}
Helpers::upsert(opCtx, _nss.ns(), docToClone, true);
}
thisTime++;
{
stdx::lock_guard<stdx::mutex> statsLock(_mutex);
_numCloned++;
_clonedBytes += docToClone.objsize();
}
if (writeConcern.shouldWaitForOtherNodes()) {
repl::ReplicationCoordinator::StatusAndDuration replStatus =
repl::getGlobalReplicationCoordinator()->awaitReplication(
opCtx,
repl::ReplClientInfo::forClient(opCtx->getClient()).getLastOp(),
writeConcern);
if (replStatus.status.code() == ErrorCodes::WriteConcernFailed) {
warning() << "secondaryThrottle on, but doc insert timed out; "
"continuing";
} else {
massertStatusOK(replStatus.status);
}
}
}
if (thisTime == 0)
break;
}
timing.done(3);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep3);
}
// If running on a replicated system, we'll need to flush the docs we cloned to the
// secondaries
repl::OpTime lastOpApplied = repl::ReplClientInfo::forClient(opCtx->getClient()).getLastOp();
const BSONObj xferModsRequest = createTransferModsRequest(_nss, *_sessionId);
{
// 4. Do bulk of mods
setState(CATCHUP);
while (true) {
BSONObj res;
if (!conn->runCommand("admin", xferModsRequest, res)) {
setStateFail(str::stream() << "_transferMods failed: " << redact(res));
conn.done();
return;
}
if (res["size"].number() == 0) {
break;
}
_applyMigrateOp(opCtx, _nss, min, max, shardKeyPattern, res, &lastOpApplied);
const int maxIterations = 3600 * 50;
int i;
for (i = 0; i < maxIterations; i++) {
opCtx->checkForInterrupt();
if (getState() == ABORT) {
log() << "Migration aborted while waiting for replication at catch up stage";
return;
}
if (opReplicatedEnough(opCtx, lastOpApplied, writeConcern))
break;
if (i > 100) {
log() << "secondaries having hard time keeping up with migrate";
}
sleepmillis(20);
}
if (i == maxIterations) {
setStateFail("secondary can't keep up with migrate");
conn.done();
return;
}
}
timing.done(4);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep4);
}
{
// Pause to wait for replication. This will prevent us from going into critical section
// until we're ready.
Timer t;
while (t.minutes() < 600) {
opCtx->checkForInterrupt();
if (getState() == ABORT) {
log() << "Migration aborted while waiting for replication";
return;
}
log() << "Waiting for replication to catch up before entering critical section";
if (_flushPendingWrites(opCtx, _nss.ns(), min, max, lastOpApplied, writeConcern)) {
break;
}
opCtx->sleepFor(Seconds(1));
}
if (t.minutes() >= 600) {
setStateFail("Cannot go to critical section because secondaries cannot keep up");
return;
}
_sessionMigration->waitUntilReadyToCommit(opCtx);
}
{
// 5. Wait for commit
setState(STEADY);
bool transferAfterCommit = false;
while (getState() == STEADY || getState() == COMMIT_START) {
opCtx->checkForInterrupt();
// Make sure we do at least one transfer after recv'ing the commit message. If we
// aren't sure that at least one transfer happens *after* our state changes to
// COMMIT_START, there could be mods still on the FROM shard that got logged
// *after* our _transferMods but *before* the critical section.
if (getState() == COMMIT_START) {
transferAfterCommit = true;
}
BSONObj res;
if (!conn->runCommand("admin", xferModsRequest, res)) {
setStateFail(str::stream() << "_transferMods failed in STEADY state: "
<< redact(res));
conn.done();
return;
}
if (res["size"].number() > 0 &&
_applyMigrateOp(opCtx, _nss, min, max, shardKeyPattern, res, &lastOpApplied)) {
continue;
}
if (getState() == ABORT) {
log() << "Migration aborted while transferring mods";
return;
}
// We know we're finished when:
// 1) The from side has told us that it has locked writes (COMMIT_START)
// 2) We've checked at least one more time for un-transmitted mods
if (getState() == COMMIT_START && transferAfterCommit == true) {
if (_flushPendingWrites(opCtx, _nss.ns(), min, max, lastOpApplied, writeConcern)) {
break;
}
}
// Only sleep if we aren't committing
if (getState() == STEADY)
sleepmillis(10);
}
if (getState() == FAIL) {
setStateFail("timed out waiting for commit");
return;
}
timing.done(5);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep5);
}
_sessionMigration->join();
if (_sessionMigration->getState() == SessionCatalogMigrationDestination::State::ErrorOccurred) {
setStateFail(_sessionMigration->getErrMsg());
return;
}
setState(DONE);
timing.done(6);
MONGO_FAIL_POINT_PAUSE_WHILE_SET(migrateThreadHangAtStep6);
conn.done();
}
bool MigrationDestinationManager::_applyMigrateOp(OperationContext* opCtx,
const NamespaceString& nss,
const BSONObj& min,
const BSONObj& max,
const BSONObj& shardKeyPattern,
const BSONObj& xfer,
repl::OpTime* lastOpApplied) {
repl::OpTime dummy;
if (lastOpApplied == NULL) {
lastOpApplied = &dummy;
}
bool didAnything = false;
if (xfer["deleted"].isABSONObj()) {
Lock::DBLock dlk(opCtx, nss.db(), MODE_IX);
Helpers::RemoveSaver rs("moveChunk", nss.ns(), "removedDuring");
BSONObjIterator i(xfer["deleted"].Obj()); // deleted documents
while (i.more()) {
Lock::CollectionLock clk(opCtx->lockState(), nss.ns(), MODE_X);
OldClientContext ctx(opCtx, nss.ns());
BSONObj id = i.next().Obj();
// do not apply delete if doc does not belong to the chunk being migrated
BSONObj fullObj;
if (Helpers::findById(opCtx, ctx.db(), nss.ns(), id, fullObj)) {
if (!isInRange(fullObj, min, max, shardKeyPattern)) {
if (MONGO_FAIL_POINT(failMigrationReceivedOutOfRangeOperation)) {
invariant(0);
}
continue;
}
}
if (serverGlobalParams.moveParanoia) {
rs.goingToDelete(fullObj).transitional_ignore();
}
deleteObjects(opCtx,
ctx.db() ? ctx.db()->getCollection(opCtx, nss) : nullptr,
nss,
id,
true /* justOne */,
false /* god */,
true /* fromMigrate */);
*lastOpApplied = repl::ReplClientInfo::forClient(opCtx->getClient()).getLastOp();
didAnything = true;
}
}
if (xfer["reload"].isABSONObj()) { // modified documents (insert/update)
BSONObjIterator i(xfer["reload"].Obj());
while (i.more()) {
OldClientWriteContext cx(opCtx, nss.ns());
BSONObj updatedDoc = i.next().Obj();
// do not apply insert/update if doc does not belong to the chunk being migrated
if (!isInRange(updatedDoc, min, max, shardKeyPattern)) {
if (MONGO_FAIL_POINT(failMigrationReceivedOutOfRangeOperation)) {
invariant(0);
}
continue;
}
BSONObj localDoc;
if (willOverrideLocalId(
opCtx, nss, min, max, shardKeyPattern, cx.db(), updatedDoc, &localDoc)) {
string errMsg = str::stream() << "cannot migrate chunk, local document " << localDoc
<< " has same _id as reloaded remote document "
<< updatedDoc;
warning() << errMsg;
// Exception will abort migration cleanly
uasserted(16977, errMsg);
}
// We are in write lock here, so sure we aren't killing
Helpers::upsert(opCtx, nss.ns(), updatedDoc, true);
*lastOpApplied = repl::ReplClientInfo::forClient(opCtx->getClient()).getLastOp();
didAnything = true;
}
}
return didAnything;
}
bool MigrationDestinationManager::_flushPendingWrites(OperationContext* opCtx,
const std::string& ns,
BSONObj min,
BSONObj max,
const repl::OpTime& lastOpApplied,
const WriteConcernOptions& writeConcern) {
if (!opReplicatedEnough(opCtx, lastOpApplied, writeConcern)) {
repl::OpTime op(lastOpApplied);
OCCASIONALLY log() << "migrate commit waiting for a majority of slaves for '" << ns << "' "
<< redact(min) << " -> " << redact(max) << " waiting for: " << op;
return false;
}
log() << "migrate commit succeeded flushing to secondaries for '" << ns << "' " << min << " -> "
<< max;
return true;
}
auto MigrationDestinationManager::_notePending(OperationContext* opCtx,
NamespaceString const& nss,
OID const& epoch,
ChunkRange const& range)
-> CollectionShardingState::CleanupNotification {
AutoGetCollection autoColl(opCtx, nss, MODE_IX, MODE_X);
auto css = CollectionShardingState::get(opCtx, nss);
auto metadata = css->getMetadata();
// This can currently happen because drops aren't synchronized with in-migrations. The idea
// for checking this here is that in the future we shouldn't have this problem.
if (!metadata || metadata->getCollVersion().epoch() != epoch) {
return Status{ErrorCodes::StaleShardVersion,
str::stream() << "not noting chunk " << redact(range.toString())
<< " as pending because the epoch of "
<< nss.ns()
<< " changed"};
}
// start clearing any leftovers that would be in the new chunk
auto notification = css->beginReceive(range);
if (notification.ready() && !notification.waitStatus(opCtx).isOK()) {
return Status{notification.waitStatus(opCtx).code(),
str::stream() << "Collection " << nss.ns() << " range " << range.toString()
<< " migration aborted: "
<< notification.waitStatus(opCtx).reason()};
}
return notification;
}
void MigrationDestinationManager::_forgetPending(OperationContext* opCtx,
const NamespaceString& nss,
OID const& epoch,
ChunkRange const& range) {
if (!_chunkMarkedPending) { // (no lock needed, only the migrate thread looks at this.)
return; // no documents can have been moved in, so there is nothing to clean up.
}
AutoGetCollection autoColl(opCtx, nss, MODE_IX, MODE_X);
auto css = CollectionShardingState::get(opCtx, nss);
auto metadata = css->getMetadata();
// This can currently happen because drops aren't synchronized with in-migrations. The idea for
// checking this here is that in the future we shouldn't have this problem.
if (!metadata || metadata->getCollVersion().epoch() != epoch) {
log() << "no need to forget pending chunk " << redact(range.toString())
<< " because the epoch for " << nss.ns() << " changed";
return;
}
css->forgetReceive(range);
}
} // namespace mongo
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