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/**
* Copyright (C) 2020-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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/storage/checkpointer.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/db/storage/kv/kv_engine.h"
#include "mongo/logv2/log.h"
#include "mongo/util/concurrency/idle_thread_block.h"
#include "mongo/util/fail_point.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kStorage
namespace mongo {
namespace {
const auto getCheckpointer = ServiceContext::declareDecoration<std::unique_ptr<Checkpointer>>();
MONGO_FAIL_POINT_DEFINE(pauseCheckpointThread);
} // namespace
Checkpointer* Checkpointer::get(ServiceContext* serviceCtx) {
return getCheckpointer(serviceCtx).get();
}
Checkpointer* Checkpointer::get(OperationContext* opCtx) {
return get(opCtx->getServiceContext());
}
void Checkpointer::set(ServiceContext* serviceCtx, std::unique_ptr<Checkpointer> newCheckpointer) {
auto& checkpointer = getCheckpointer(serviceCtx);
if (checkpointer) {
invariant(!checkpointer->running(),
"Tried to reset the Checkpointer without shutting down the original instance.");
}
checkpointer = std::move(newCheckpointer);
}
void Checkpointer::run() {
ThreadClient tc(name(), getGlobalServiceContext());
LOGV2_DEBUG(22307, 1, "Starting thread", "threadName"_attr = name());
{
stdx::lock_guard<Client> lk(*tc.get());
tc.get()->setSystemOperationUnkillableByStepdown(lk);
}
while (true) {
auto opCtx = tc->makeOperationContext();
{
stdx::unique_lock<Latch> lock(_mutex);
MONGO_IDLE_THREAD_BLOCK;
// Wait for 'storageGlobalParams.syncdelay' seconds; or until either shutdown is
// signaled or a checkpoint is triggered.
LOGV2_DEBUG(7702900,
1,
"Checkpoint thread sleeping",
"duration"_attr = static_cast<std::int64_t>(storageGlobalParams.syncdelay));
_sleepCV.wait_for(
lock,
stdx::chrono::seconds(static_cast<std::int64_t>(storageGlobalParams.syncdelay)),
[&] { return _shuttingDown || _triggerCheckpoint; });
// If the syncdelay is set to 0, that means we should skip checkpointing. However,
// syncdelay is adjustable by a runtime server parameter, so we need to wake up to check
// periodically. The wakeup to check period is arbitrary.
while (storageGlobalParams.syncdelay == 0 && !_shuttingDown && !_triggerCheckpoint) {
_sleepCV.wait_for(lock, stdx::chrono::seconds(static_cast<std::int64_t>(3)), [&] {
return _shuttingDown || _triggerCheckpoint;
});
}
if (_shuttingDown) {
invariant(!_shutdownReason.isOK());
LOGV2_DEBUG(22309,
1,
"Stopping thread",
"threadName"_attr = name(),
"reason"_attr = _shutdownReason);
return;
}
// Clear the trigger so we do not immediately checkpoint again after this.
_triggerCheckpoint = false;
}
pauseCheckpointThread.pauseWhileSet();
const Date_t startTime = Date_t::now();
opCtx->getServiceContext()->getStorageEngine()->checkpoint(opCtx.get());
const auto secondsElapsed = durationCount<Seconds>(Date_t::now() - startTime);
if (secondsElapsed >= 30) {
LOGV2_DEBUG(22308,
1,
"Checkpoint was slow to complete",
"secondsElapsed"_attr = secondsElapsed);
}
}
}
void Checkpointer::triggerFirstStableCheckpoint(Timestamp prevStable,
Timestamp initialData,
Timestamp currStable) {
stdx::unique_lock<Latch> lock(_mutex);
invariant(!_hasTriggeredFirstStableCheckpoint);
if (prevStable < initialData && currStable >= initialData) {
LOGV2(22310,
"Triggering the first stable checkpoint",
"initialDataTimestamp"_attr = initialData,
"prevStableTimestamp"_attr = prevStable,
"currStableTimestamp"_attr = currStable);
_hasTriggeredFirstStableCheckpoint = true;
_triggerCheckpoint = true;
_sleepCV.notify_one();
}
}
bool Checkpointer::hasTriggeredFirstStableCheckpoint() {
stdx::unique_lock<Latch> lock(_mutex);
return _hasTriggeredFirstStableCheckpoint;
}
void Checkpointer::shutdown(const Status& reason) {
LOGV2(22322, "Shutting down checkpoint thread");
{
stdx::unique_lock<Latch> lock(_mutex);
_shuttingDown = true;
_shutdownReason = reason;
// Wake up the checkpoint thread early, to take a final checkpoint before shutting down, if
// one has not coincidentally just been taken.
_sleepCV.notify_one();
}
wait();
LOGV2(22323, "Finished shutting down checkpoint thread");
}
} // namespace mongo
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