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/**
* Copyright (C) 2017 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::kDefault
#include "mongo/platform/basic.h"
#include "mongo/db/logical_clock.h"
#include "mongo/base/status.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/server_parameters.h"
#include "mongo/db/service_context.h"
#include "mongo/db/time_proof_service.h"
#include "mongo/util/log.h"
namespace mongo {
constexpr Seconds LogicalClock::kMaxAcceptableLogicalClockDrift;
server_parameter_storage_type<long long, ServerParameterType::kStartupOnly>::value_type
maxAcceptableLogicalClockDrift(LogicalClock::kMaxAcceptableLogicalClockDrift.count());
class MaxAcceptableLogicalClockDrift
: public ExportedServerParameter<long long, ServerParameterType::kStartupOnly> {
public:
MaxAcceptableLogicalClockDrift()
: ExportedServerParameter<long long, ServerParameterType::kStartupOnly>(
ServerParameterSet::getGlobal(),
"maxAcceptableLogicalClockDrift",
&maxAcceptableLogicalClockDrift) {}
Status validate(const long long& potentialNewValue) {
if (potentialNewValue < 0) {
return Status(ErrorCodes::BadValue,
str::stream() << "maxAcceptableLogicalClockDrift cannot be negative, but "
"attempted to set to: "
<< potentialNewValue);
}
return Status::OK();
}
} maxAcceptableLogicalClockDriftParameter;
namespace {
const auto getLogicalClock = ServiceContext::declareDecoration<std::unique_ptr<LogicalClock>>();
}
LogicalClock* LogicalClock::get(ServiceContext* service) {
return getLogicalClock(service).get();
}
LogicalClock* LogicalClock::get(OperationContext* ctx) {
return get(ctx->getClient()->getServiceContext());
}
void LogicalClock::set(ServiceContext* service, std::unique_ptr<LogicalClock> clockArg) {
auto& clock = getLogicalClock(service);
clock = std::move(clockArg);
}
LogicalClock::LogicalClock(ServiceContext* service, std::unique_ptr<TimeProofService> tps)
: _service(service), _timeProofService(std::move(tps)) {}
SignedLogicalTime LogicalClock::getClusterTime() {
stdx::lock_guard<stdx::mutex> lock(_mutex);
return _clusterTime;
}
SignedLogicalTime LogicalClock::_makeSignedLogicalTime(LogicalTime logicalTime) {
// TODO: SERVER-28436 Implement KeysCollectionManager
// Replace dummy keyId with real id from key manager.
return SignedLogicalTime(logicalTime, _timeProofService->getProof(logicalTime, _tempKey), 0);
}
Status LogicalClock::advanceClusterTime(const SignedLogicalTime& newTime) {
const auto& newLogicalTime = newTime.getTime();
// No need to check proof if no time was given.
if (newLogicalTime == LogicalTime::kUninitialized) {
return Status::OK();
}
invariant(_timeProofService);
auto res = _timeProofService->checkProof(newLogicalTime, newTime.getProof(), _tempKey);
if (res != Status::OK()) {
return res;
}
return advanceClusterTimeFromTrustedSource(newTime);
}
Status LogicalClock::_advanceClusterTime_inlock(SignedLogicalTime newTime) {
if (newTime.getTime() > _clusterTime.getTime()) {
_clusterTime = newTime;
}
return Status::OK();
}
Status LogicalClock::advanceClusterTimeFromTrustedSource(SignedLogicalTime newTime) {
stdx::lock_guard<stdx::mutex> lock(_mutex);
auto rateLimitStatus = _passesRateLimiter_inlock(newTime.getTime());
if (!rateLimitStatus.isOK()) {
return rateLimitStatus;
}
return _advanceClusterTime_inlock(std::move(newTime));
}
Status LogicalClock::signAndAdvanceClusterTime(LogicalTime newTime) {
auto newSignedTime = _makeSignedLogicalTime(newTime);
stdx::lock_guard<stdx::mutex> lock(_mutex);
return _advanceClusterTime_inlock(std::move(newSignedTime));
}
LogicalTime LogicalClock::reserveTicks(uint64_t nTicks) {
invariant(nTicks > 0 && nTicks < (1U << 31));
stdx::lock_guard<stdx::mutex> lock(_mutex);
LogicalTime clusterTime = _clusterTime.getTime();
LogicalTime nextClusterTime;
const unsigned wallClockSecs =
durationCount<Seconds>(_service->getFastClockSource()->now().toDurationSinceEpoch());
unsigned clusterTimeSecs = clusterTime.asTimestamp().getSecs();
// Synchronize clusterTime with wall clock time, if clusterTime was behind in seconds.
if (clusterTimeSecs < wallClockSecs) {
clusterTime = LogicalTime(Timestamp(wallClockSecs, 0));
}
// If reserving 'nTicks' would force the cluster timestamp's increment field to exceed (2^31-1),
// overflow by moving to the next second. We use the signed integer maximum as an overflow point
// in order to preserve compatibility with potentially signed or unsigned integral Timestamp
// increment types. It is also unlikely to apply more than 2^31 oplog entries in the span of one
// second.
else if (clusterTime.asTimestamp().getInc() >= ((1U << 31) - nTicks)) {
log() << "Exceeded maximum allowable increment value within one second. Moving clusterTime "
"forward to the next second.";
// Move time forward to the next second
clusterTime = LogicalTime(Timestamp(clusterTime.asTimestamp().getSecs() + 1, 0));
}
// Save the next cluster time.
clusterTime.addTicks(1);
nextClusterTime = clusterTime;
// Add the rest of the requested ticks if needed.
if (nTicks > 1) {
clusterTime.addTicks(nTicks - 1);
}
_clusterTime = _makeSignedLogicalTime(clusterTime);
return nextClusterTime;
}
void LogicalClock::initClusterTimeFromTrustedSource(LogicalTime newTime) {
invariant(_clusterTime.getTime() == LogicalTime::kUninitialized);
// Rate limit checks are skipped here so a server with no activity for longer than
// maxAcceptableLogicalClockDrift seconds can still have its cluster time initialized.
_clusterTime = _makeSignedLogicalTime(newTime);
}
Status LogicalClock::_passesRateLimiter_inlock(LogicalTime newTime) {
const unsigned wallClockSecs =
durationCount<Seconds>(_service->getFastClockSource()->now().toDurationSinceEpoch());
auto maxAcceptableDrift = static_cast<const unsigned>(maxAcceptableLogicalClockDrift);
auto newTimeSecs = newTime.asTimestamp().getSecs();
// Both values are unsigned, so compare them first to avoid wrap-around.
if ((newTimeSecs > wallClockSecs) && (newTimeSecs - wallClockSecs) > maxAcceptableDrift) {
return Status(ErrorCodes::ClusterTimeFailsRateLimiter,
str::stream() << "New cluster time, " << newTimeSecs
<< ", is too far from this node's wall clock time, "
<< wallClockSecs
<< ".");
}
return Status::OK();
}
} // namespace mongo
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