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/**
* Copyright (C) 2023-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/db/change_stream_pre_image_util.h"
#include "mongo/db/change_stream_options_manager.h"
#include "mongo/db/change_stream_serverless_helpers.h"
#include "mongo/db/record_id_helpers.h"
#include "mongo/util/fail_point.h"
namespace mongo {
// Fail point to set current time for time-based expiration of pre-images.
MONGO_FAIL_POINT_DEFINE(changeStreamPreImageRemoverCurrentTime);
namespace change_stream_pre_image_util {
namespace {
// Get the 'expireAfterSeconds' from the 'ChangeStreamOptions' if not 'off', boost::none otherwise.
boost::optional<std::int64_t> getExpireAfterSecondsFromChangeStreamOptions(
ChangeStreamOptions& changeStreamOptions) {
const stdx::variant<std::string, std::int64_t>& expireAfterSeconds =
changeStreamOptions.getPreAndPostImages().getExpireAfterSeconds();
if (!stdx::holds_alternative<std::string>(expireAfterSeconds)) {
return stdx::get<std::int64_t>(expireAfterSeconds);
}
return boost::none;
}
} // namespace
boost::optional<Date_t> getPreImageExpirationTime(OperationContext* opCtx, Date_t currentTime) {
// Non-serverless and serverless environments expire pre-images according to different logic and
// parameters. This method retrieves the 'expireAfterSeconds' for a single-tenant environment.
boost::optional<std::int64_t> expireAfterSeconds = boost::none;
// Get the expiration time directly from the change stream manager.
auto changeStreamOptions = ChangeStreamOptionsManager::get(opCtx).getOptions(opCtx);
expireAfterSeconds = getExpireAfterSecondsFromChangeStreamOptions(changeStreamOptions);
// A pre-image is eligible for deletion if:
// pre-image's op-time + expireAfterSeconds < currentTime.
return expireAfterSeconds ? boost::optional<Date_t>(currentTime - Seconds(*expireAfterSeconds))
: boost::none;
}
Timestamp getPreImageTimestamp(const RecordId& rid) {
static constexpr auto kTopLevelFieldName = "ridAsBSON"_sd;
auto ridAsNestedBSON = record_id_helpers::toBSONAs(rid, kTopLevelFieldName);
// 'toBSONAs()' discards type bits of the underlying KeyString of the RecordId. However, since
// the 'ts' field of 'ChangeStreamPreImageId' is distinct CType::kTimestamp, type bits aren't
// necessary to obtain the original value.
auto ridBSON = ridAsNestedBSON.getObjectField(kTopLevelFieldName);
// Callers must ensure the 'rid' represents an underlying 'ChangeStreamPreImageId'. Otherwise,
// the behavior of this method is undefined.
invariant(ridBSON.hasField(ChangeStreamPreImageId::kTsFieldName));
auto tsElem = ridBSON.getField(ChangeStreamPreImageId::kTsFieldName);
return tsElem.timestamp();
}
RecordId toRecordId(ChangeStreamPreImageId id) {
return record_id_helpers::keyForElem(
BSON(ChangeStreamPreImage::kIdFieldName << id.toBSON()).firstElement());
}
RecordIdBound getAbsoluteMinPreImageRecordIdBoundForNs(const UUID& nsUUID) {
return RecordIdBound(
change_stream_pre_image_util::toRecordId(ChangeStreamPreImageId(nsUUID, Timestamp(), 0)));
}
RecordIdBound getAbsoluteMaxPreImageRecordIdBoundForNs(const UUID& nsUUID) {
return RecordIdBound(change_stream_pre_image_util::toRecordId(
ChangeStreamPreImageId(nsUUID, Timestamp::max(), std::numeric_limits<int64_t>::max())));
}
boost::optional<UUID> findNextCollectionUUID(OperationContext* opCtx,
const CollectionPtr* preImagesCollPtr,
boost::optional<UUID> currentNsUUID,
Date_t& firstDocWallTime) {
BSONObj preImageObj;
// Make the minRecordId for the next collection UUID the maximum RecordId for the current
// 'currentNsUUID'.
auto minRecordId = currentNsUUID
? boost::make_optional(
change_stream_pre_image_util::getAbsoluteMaxPreImageRecordIdBoundForNs(
*currentNsUUID))
: boost::none;
auto planExecutor =
InternalPlanner::collectionScan(opCtx,
preImagesCollPtr,
PlanYieldPolicy::YieldPolicy::INTERRUPT_ONLY,
InternalPlanner::Direction::FORWARD,
boost::none /* resumeAfterRecordId */,
std::move(minRecordId));
if (planExecutor->getNext(&preImageObj, nullptr) == PlanExecutor::IS_EOF) {
return boost::none;
}
auto parsedUUID = UUID::parse(preImageObj["_id"].Obj()["nsUUID"]);
tassert(7027400, "Pre-image collection UUID must be of UUID type", parsedUUID.isOK());
firstDocWallTime = preImageObj[ChangeStreamPreImage::kOperationTimeFieldName].date();
return {std::move(parsedUUID.getValue())};
}
Date_t getCurrentTimeForPreImageRemoval() {
auto currentTime = Date_t::now();
changeStreamPreImageRemoverCurrentTime.execute([&](const BSONObj& data) {
// Populate the current time for time based expiration of pre-images.
if (auto currentTimeElem = data["currentTimeForTimeBasedExpiration"]) {
const BSONType bsonType = currentTimeElem.type();
tassert(7500501,
str::stream() << "Expected type for 'currentTimeForTimeBasedExpiration' is "
"'date', but found: "
<< bsonType,
bsonType == BSONType::Date);
currentTime = currentTimeElem.Date();
}
});
return currentTime;
}
} // namespace change_stream_pre_image_util
} // namespace mongo
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