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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.
*/
#pragma once
#include <cstdint>
#include <memory>
#include <type_traits>
#include "mongo/db/storage/kv/kv_catalog.h"
namespace mongo {
class OperationContext;
class RecordId;
class RecordStore;
/**
* Manages the contents of a document in the KVCatalog used to restrict downgrade compatibility.
*
* When a new feature is enabled on a collection or index in the data files, a bit is set in one of
* the fields of the document. Older versions won't recognize this bit and will fail to start up as
* a result.
*
* The inserted document serves a similar purpose to the DataFileVersion class used with the MMAPv1
* storage engine.
*/
class KVCatalog::FeatureTracker {
public:
/**
* Bit flags representing whether a particular feature is enabled on a least one collection or
* index in the data files. Features included in this enumeration always require user
* intervention on downgrade.
*
* The next feature added to this enumeration should use the current value of 'kNextFeatureBit',
* and 'kNextFeatureBit' should be changed to the next largest power of two.
*/
enum class NonRepairableFeature : std::uint64_t {
kCollation = 1 << 0,
kNextFeatureBit = 1 << 1
};
using NonRepairableFeatureMask = std::underlying_type<NonRepairableFeature>::type;
/**
* Bit flags representing whether a particular feature is enabled on a least one collection or
* index in the data files. Features included in this enumeration either (a) don't require user
* intervention on downgrade, or (b) are no longer enabled if --repair is done with an older
* version.
*
* The next feature added to this enumeration should use the current value of 'kNextFeatureBit',
* and 'kNextFeatureBit' should be changed to the next largest power of two.
*/
enum class RepairableFeature : std::uint64_t {
kPathLevelMultikeyTracking = 1 << 0,
// TODO SERVER-36385: Mark kIndexKeyStringWithLongTypeBits as obsolete in 4.4 because 4.4
// can only downgrade to 4.2 which can read long TypeBits.
kIndexKeyStringWithLongTypeBits = 1 << 1,
kNextFeatureBit = 1 << 2
};
using RepairableFeatureMask = std::underlying_type<RepairableFeature>::type;
/**
* Returns true if 'obj' represents the contents of the feature document that was previously
* inserted into the KVCatalog, and returns false otherwise.
*
* This function should return true for at most one document in the KVCatalog.
*/
static bool isFeatureDocument(BSONObj obj);
/**
* Returns a FeatureTracker instance to manage the contents of the feature document located at
* 'rid' in the record store 'catalog->_rs'.
*
* It is invalid to call this function when isFeatureDocument() returns false for the record
* data associated with 'rid'.
*/
static std::unique_ptr<FeatureTracker> get(OperationContext* opCtx,
KVCatalog* catalog,
RecordId rid);
/**
* Returns a FeatureTracker instance to manage the contents of a feature document. The feature
* document isn't inserted into 'rs' as a result of calling this function. Instead, the feature
* document is inserted into 'rs' when putInfo() is first called.
*
* It is invalid to call this function when isFeatureDocument() returns true for some document
* in the record store 'catalog->_rs'.
*/
static std::unique_ptr<FeatureTracker> create(OperationContext* opCtx, KVCatalog* catalog);
/**
* Returns whethers the data files are compatible with the current code:
*
* - Status::OK() if the data files are compatible with the current code.
*
* - ErrorCodes::CanRepairToDowngrade if the data files are incompatible with the current
* code, but a --repair would make them compatible. For example, when rebuilding all indexes
* in the data files would resolve the incompatibility.
*
* - ErrorCodes::MustUpgrade if the data files are incompatible with the current code and a
* newer version is required to start up.
*/
Status isCompatibleWithCurrentCode(OperationContext* opCtx) const;
/**
* Returns true if 'feature' is tracked in the document, and returns false otherwise.
*/
bool isNonRepairableFeatureInUse(OperationContext* opCtx, NonRepairableFeature feature) const;
/**
* Sets the specified non-repairable feature as being enabled on at least one collection or
* index in the data files.
*/
void markNonRepairableFeatureAsInUse(OperationContext* opCtx, NonRepairableFeature feature);
/**
* Sets the specified non-repairable feature as not being enabled on any collection or index in
* the data files.
*/
void markNonRepairableFeatureAsNotInUse(OperationContext* opCtx, NonRepairableFeature feature);
/**
* Returns true if 'feature' is tracked in the document, and returns false otherwise.
*/
bool isRepairableFeatureInUse(OperationContext* opCtx, RepairableFeature feature) const;
/**
* Sets the specified repairable feature as being enabled on at least one collection or index in
* the data files.
*/
void markRepairableFeatureAsInUse(OperationContext* opCtx, RepairableFeature feature);
/**
* Sets the specified repairable feature as not being enabled on any collection or index in the
* data files.
*/
void markRepairableFeatureAsNotInUse(OperationContext* opCtx, RepairableFeature feature);
void setUsedNonRepairableFeaturesMaskForTestingOnly(NonRepairableFeatureMask mask) {
_usedNonRepairableFeaturesMask = mask;
}
void setUsedRepairableFeaturesMaskForTestingOnly(RepairableFeatureMask mask) {
_usedRepairableFeaturesMask = mask;
}
struct FeatureBits {
NonRepairableFeatureMask nonRepairableFeatures;
RepairableFeatureMask repairableFeatures;
};
FeatureBits getInfo(OperationContext* opCtx) const;
void putInfo(OperationContext* opCtx, const FeatureBits& versionInfo);
private:
// Must go through FeatureTracker::get() or FeatureTracker::create().
FeatureTracker(KVCatalog* catalog, RecordId rid) : _catalog(catalog), _rid(rid) {}
KVCatalog* _catalog;
RecordId _rid;
NonRepairableFeatureMask _usedNonRepairableFeaturesMask =
static_cast<NonRepairableFeatureMask>(NonRepairableFeature::kNextFeatureBit) - 1;
RepairableFeatureMask _usedRepairableFeaturesMask =
static_cast<RepairableFeatureMask>(RepairableFeature::kNextFeatureBit) - 1;
};
} // namespace mongo
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