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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kReplicationRollback
#include "mongo/platform/basic.h"
#include "mongo/db/repl/roll_back_local_operations.h"
#include "mongo/logv2/log.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/str.h"
namespace mongo {
namespace repl {
// After the release of MongoDB 3.8, these fail point declarations can
// be moved into the rs_rollback.cpp file, as we no longer need to maintain
// functionality for rs_rollback_no_uuid.cpp. See SERVER-29766.
// Failpoint which causes rollback to hang before finishing.
MONGO_FAIL_POINT_DEFINE(rollbackHangBeforeFinish);
// Failpoint which causes rollback to hang and then fail after minValid is written.
MONGO_FAIL_POINT_DEFINE(rollbackHangThenFailAfterWritingMinValid);
namespace {
constexpr int kMaxConnectionAttempts = 3;
OpTime getOpTime(const OplogInterface::Iterator::Value& oplogValue) {
return fassert(40298, OpTime::parseFromOplogEntry(oplogValue.first));
}
long long getTerm(const BSONObj& operation) {
return operation["t"].numberLong();
}
Timestamp getTimestamp(const BSONObj& operation) {
return operation["ts"].timestamp();
}
Timestamp getTimestamp(const OplogInterface::Iterator::Value& oplogValue) {
return getTimestamp(oplogValue.first);
}
long long getTerm(const OplogInterface::Iterator::Value& oplogValue) {
return getTerm(oplogValue.first);
}
} // namespace
RollBackLocalOperations::RollBackLocalOperations(const OplogInterface& localOplog,
const RollbackOperationFn& rollbackOperation)
: _localOplogIterator(localOplog.makeIterator()),
_rollbackOperation(rollbackOperation),
_scanned(0) {
uassert(ErrorCodes::BadValue, "invalid local oplog iterator", _localOplogIterator);
uassert(ErrorCodes::BadValue, "null roll back operation function", rollbackOperation);
}
RollBackLocalOperations::RollbackCommonPoint::RollbackCommonPoint(BSONObj oplogBSON,
RecordId recordId,
BSONObj nextOplogBSON)
: _recordId(std::move(recordId)) {
auto oplogEntry = uassertStatusOK(repl::OplogEntry::parse(oplogBSON));
_opTime = oplogEntry.getOpTime();
_wallClockTime = oplogEntry.getWallClockTime();
// nextOplogEntry holds the oplog entry immediately after the common point.
auto nextOplogEntry = uassertStatusOK(repl::OplogEntry::parse(nextOplogBSON));
_firstWallClockTimeAfterCommonPoint = nextOplogEntry.getWallClockTime();
}
StatusWith<RollBackLocalOperations::RollbackCommonPoint> RollBackLocalOperations::onRemoteOperation(
const BSONObj& operation) {
if (_scanned == 0) {
auto result = _localOplogIterator->next();
if (!result.isOK()) {
return Status(ErrorCodes::OplogStartMissing, "no oplog during rollback");
}
_localOplogValue = result.getValue();
}
// As we iterate through the oplog in reverse, opAfterCurrentEntry holds the oplog entry
// immediately after the entry stored in _localOplogValue.
BSONObj opAfterCurrentEntry = _localOplogValue.first;
while (getTimestamp(_localOplogValue) > getTimestamp(operation)) {
_scanned++;
LOGV2_DEBUG(21656,
2,
"Local oplog entry to roll back: {oplogEntry}",
"Local oplog entry to roll back",
"oplogEntry"_attr = redact(_localOplogValue.first));
auto status = _rollbackOperation(_localOplogValue.first);
if (!status.isOK()) {
invariant(ErrorCodes::NoSuchKey != status.code());
return status;
}
auto result = _localOplogIterator->next();
if (!result.isOK()) {
return Status(ErrorCodes::NoMatchingDocument,
str::stream()
<< "reached beginning of local oplog: {"
<< "scanned: " << _scanned
<< ", theirTime: " << getTimestamp(operation).toString()
<< ", ourTime: " << getTimestamp(_localOplogValue).toString() << "}");
}
opAfterCurrentEntry = _localOplogValue.first;
_localOplogValue = result.getValue();
}
if (getTimestamp(_localOplogValue) == getTimestamp(operation)) {
_scanned++;
if (getTerm(_localOplogValue) == getTerm(operation)) {
return RollbackCommonPoint(
_localOplogValue.first, _localOplogValue.second, opAfterCurrentEntry);
}
// We don't need to advance the localOplogIterator here because it is guaranteed to advance
// during the next call to onRemoteOperation. This is because before the next call to
// onRemoteOperation, the remote oplog iterator will advance and the new remote operation is
// guaranteed to have a timestamp less than the current local operation, which will trigger
// a call to get the next local operation.
return Status(ErrorCodes::NoSuchKey,
"Unable to determine common point - same timestamp but different terms. "
"Need to process additional remote operations.");
}
invariant(getTimestamp(_localOplogValue) < getTimestamp(operation));
_scanned++;
return Status(ErrorCodes::NoSuchKey,
"Unable to determine common point. "
"Need to process additional remote operations.");
}
StatusWith<RollBackLocalOperations::RollbackCommonPoint> syncRollBackLocalOperations(
const OplogInterface& localOplog,
const OplogInterface& remoteOplog,
const RollBackLocalOperations::RollbackOperationFn& rollbackOperation) {
std::unique_ptr<OplogInterface::Iterator> remoteIterator;
// Retry in case of network errors.
for (int attemptsLeft = kMaxConnectionAttempts - 1; attemptsLeft >= 0; attemptsLeft--) {
try {
remoteIterator = remoteOplog.makeIterator();
} catch (DBException&) {
if (attemptsLeft == 0) {
throw;
}
}
}
invariant(remoteIterator);
auto remoteResult = remoteIterator->next();
if (!remoteResult.isOK()) {
return Status(ErrorCodes::InvalidSyncSource, remoteResult.getStatus().reason())
.withContext("remote oplog empty or unreadable");
}
RollBackLocalOperations finder(localOplog, rollbackOperation);
Timestamp theirTime;
while (remoteResult.isOK()) {
BSONObj theirObj = remoteResult.getValue().first;
theirTime = theirObj["ts"].timestamp();
auto result = finder.onRemoteOperation(theirObj);
if (result.isOK()) {
return result.getValue();
} else if (result.getStatus().code() != ErrorCodes::NoSuchKey) {
return result;
}
remoteResult = remoteIterator->next();
}
return Status(ErrorCodes::NoMatchingDocument,
str::stream() << "reached beginning of remote oplog: {"
<< "them: " << remoteOplog.toString()
<< ", theirTime: " << theirTime.toString() << "}");
}
} // namespace repl
} // namespace mongo
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