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/**
* Copyright (C) 2021-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.
*/
#pragma once
#include <boost/optional/optional.hpp>
#include "mongo/db/change_stream_pre_images_truncate_markers.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/pipeline/change_stream_preimage_gen.h"
#include "mongo/db/shard_role.h"
#include "mongo/db/tenant_id.h"
#include "mongo/util/background.h"
#include "mongo/util/concurrent_shared_values_map.h"
namespace mongo {
/**
* Manages the lifecycle of the change stream pre-images collection(s). Also is responsible for
* inserting the pre-images into the pre-images collection.
*/
class ChangeStreamPreImagesCollectionManager {
public:
struct PurgingJobStats {
/**
* Total number of deletion passes completed by the purging job.
*/
AtomicWord<int64_t> totalPass;
/**
* Cumulative number of pre-image documents deleted by the purging job.
*/
AtomicWord<int64_t> docsDeleted;
/**
* Cumulative size in bytes of all deleted documents from all pre-image collections by the
* purging job.
*/
AtomicWord<int64_t> bytesDeleted;
/**
* Cumulative number of pre-image collections scanned by the purging job. In single-tenant
* environments this is the same as totalPass as there is 1 pre-image collection per tenant.
*/
AtomicWord<int64_t> scannedCollections;
/**
* Cumulative number of internal pre-image collections scanned by the purging job. Internal
* collections are the segments of actual pre-images of collections within system.preimages.
*/
AtomicWord<int64_t> scannedInternalCollections;
/**
* Cumulative number of milliseconds elapsed since the first pass by the purging job.
*/
AtomicWord<int64_t> timeElapsedMillis;
/**
* Maximum wall time from the first document of each pre-image collection.
*/
AtomicWord<Date_t> maxStartWallTime;
/**
* Serializes the purging job statistics to the BSON object.
*/
BSONObj toBSON() const;
};
explicit ChangeStreamPreImagesCollectionManager() {}
~ChangeStreamPreImagesCollectionManager() = default;
/**
* Gets the instance of the class using the service context.
*/
static ChangeStreamPreImagesCollectionManager& get(ServiceContext* service);
/**
* Gets the instance of the class using the operation context.
*/
static ChangeStreamPreImagesCollectionManager& get(OperationContext* opCtx);
/**
* Creates the pre-images collection, clustered by the primary key '_id'. The collection is
* created for the specific tenant if the 'tenantId' is specified.
*/
void createPreImagesCollection(OperationContext* opCtx, boost::optional<TenantId> tenantId);
/**
* Drops the pre-images collection. The collection is dropped for the specific tenant if
* the 'tenantId' is specified.
*/
void dropPreImagesCollection(OperationContext* opCtx, boost::optional<TenantId> tenantId);
/**
* Inserts the document into the pre-images collection. The document is inserted into the
* tenant's pre-images collection if the 'tenantId' is specified.
*/
void insertPreImage(OperationContext* opCtx,
boost::optional<TenantId> tenantId,
const ChangeStreamPreImage& preImage);
/**
* Scans the system pre-images collection and deletes the expired pre-images from it.
*/
void performExpiredChangeStreamPreImagesRemovalPass(Client* client);
const PurgingJobStats& getPurgingJobStats() {
return _purgingJobStats;
}
private:
/**
* Scans the 'config.system.preimages' collection and deletes the expired pre-images from it.
*
* Pre-images are ordered by collection UUID, ie. if UUID of collection A is ordered before UUID
* of collection B, then pre-images of collection A will be stored before pre-images of
* collection B.
*
* Pre-images are considered expired based on expiration parameter. In case when expiration
* parameter is not set a pre-image is considered expired if its timestamp is smaller than the
* timestamp of the earliest oplog entry. In case when expiration parameter is specified, aside
* from timestamp check a check on the wall clock time of the pre-image recording
* ('operationTime') is performed. If the difference between 'currentTimeForTimeBasedExpiration'
* and 'operationTime' is larger than expiration parameter, the pre-image is considered expired.
* One of those two conditions must be true for a pre-image to be eligible for deletion.
*
* +-------------------------+
* | config.system.preimages |
* +------------+------------+
* |
* +--------------------+---------+---------+-----------------------+
* | | | |
* +-----------+-------+ +----------+--------+ +--------+----------+ +----------+--------+
* | collA.preImageA | | collA.preImageB | | collB.preImageC | | collB.preImageD |
* +-----------+-------+ +----------+--------+ +---------+---------+ +----------+--------+
* | timestamp: 1 | | timestamp: 10 | | timestamp: 5 | | timestamp: 9 |
* | applyIndex: 0 | | applyIndex: 0 | | applyIndex: 0 | | applyIndex: 1 |
* +-------------------+ +-------------------+ +-------------------+ +-------------------+
*/
/**
* Common logic for removing expired pre-images with a collection scan.
*/
size_t _deleteExpiredPreImagesWithCollScanCommon(
OperationContext* opCtx,
const ScopedCollectionAcquisition& preImageColl,
const MatchExpression* filterPtr,
Timestamp maxRecordIdTimestamp);
/**
* Removes expired pre-images in a single tenant enviornment.
*/
size_t _deleteExpiredPreImagesWithCollScan(OperationContext* opCtx,
Date_t currentTimeForTimeBasedExpiration);
/**
* Removes expired pre-images for the tenant with 'tenantId'.
*/
size_t _deleteExpiredPreImagesWithCollScanForTenants(OperationContext* opCtx,
const TenantId& tenantId,
Date_t currentTimeForTimeBasedExpiration);
/**
* Removes expired pre-images with truncate. Suitable for both serverless and single tenant
* enviornments. 'tenantId' is boost::none in a single tenant enviornment.
*
* Performs lazy initialisation of truncate markers upon creation of the tenant's pre-images
* collection upon startup.
*/
size_t _deleteExpiredPreImagesWithTruncate(OperationContext* opCtx,
boost::optional<TenantId> tenantId);
PurgingJobStats _purgingJobStats;
/**
* A map which represents the truncate markers for an entire "config.system.preimages"
* collection.
*/
using PreImagesCollectionTruncateMap =
ConcurrentSharedValuesMap<UUID, PreImagesTruncateMarkersPerCollection, UUID::Hash>;
using TenantToPreImagesCollectionTruncateMap =
ConcurrentSharedValuesMap<boost::optional<TenantId>, PreImagesCollectionTruncateMap>;
/**
* Maps a 'tenantId' to its corresponding 'config.system.preimages'
* PreImagesCollectionTruncateMap.
*
* In a single-tenant environment, 'tenantId' is boost::none.
*/
TenantToPreImagesCollectionTruncateMap _tenantTruncateMarkersMap;
};
} // namespace mongo
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