kv_storage_engine.h

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#pragma once

#include <map>
#include <string>

#include "mongo/base/status_with.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/storage/journal_listener.h"
#include "mongo/db/storage/kv/kv_catalog.h"
#include "mongo/db/storage/kv/kv_database_catalog_entry_base.h"
#include "mongo/db/storage/record_store.h"
#include "mongo/db/storage/storage_engine.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/memory.h"
#include "mongo/stdx/mutex.h"

namespace mongo {

class KVCatalog;
class KVEngine;

struct KVStorageEngineOptions {
    bool directoryPerDB = false;
    bool directoryForIndexes = false;
    bool forRepair = false;
};

/*
 * The actual definition for this function is in
 * `src/mongo/db/storage/kv/kv_database_catalog_entry.cpp` This unusual forward declaration is to
 * facilitate better linker error messages.  Tests need to pass a mock construction factory, whereas
 * main implementations should pass the `default...` factory which is linked in with the main
 * `KVDatabaseCatalogEntry` code.
 */
std::unique_ptr<KVDatabaseCatalogEntryBase> defaultDatabaseCatalogEntryFactory(
    const StringData name, KVStorageEngine* const engine);

using KVDatabaseCatalogEntryFactory = decltype(defaultDatabaseCatalogEntryFactory);

class KVStorageEngine final : public StorageEngine {
public:
    KVStorageEngine(KVEngine* engine,
                    const KVStorageEngineOptions& options = KVStorageEngineOptions(),
                    stdx::function<KVDatabaseCatalogEntryFactory> databaseCatalogEntryFactory =
                        defaultDatabaseCatalogEntryFactory);

    virtual ~KVStorageEngine();

    virtual void finishInit();

    virtual RecoveryUnit* newRecoveryUnit();

    virtual void listDatabases(std::vector<std::string>* out) const;

    KVDatabaseCatalogEntryBase* getDatabaseCatalogEntry(OperationContext* opCtx,
                                                        StringData db) override;

    virtual bool supportsDocLocking() const {
        return _supportsDocLocking;
    }

    virtual bool supportsDBLocking() const {
        return _supportsDBLocking;
    }

    virtual bool supportsCappedCollections() const {
        return _supportsCappedCollections;
    }

    virtual Status closeDatabase(OperationContext* opCtx, StringData db);

    virtual Status dropDatabase(OperationContext* opCtx, StringData db);

    virtual int flushAllFiles(OperationContext* opCtx, bool sync);

    virtual Status beginBackup(OperationContext* opCtx);

    virtual void endBackup(OperationContext* opCtx);

    virtual bool isDurable() const;

    virtual bool isEphemeral() const;

    virtual Status repairRecordStore(OperationContext* opCtx, const std::string& ns);

    virtual void cleanShutdown();

    virtual void setStableTimestamp(Timestamp stableTimestamp) override;

    virtual void setInitialDataTimestamp(Timestamp initialDataTimestamp) override;

    virtual void setOldestTimestampFromStable() override;

    virtual void setOldestTimestamp(Timestamp newOldestTimestamp) override;

    virtual bool isCacheUnderPressure(OperationContext* opCtx) const override;

    virtual void setCachePressureForTest(int pressure) override;

    virtual bool supportsRecoverToStableTimestamp() const override;

    virtual StatusWith<Timestamp> recoverToStableTimestamp(OperationContext* opCtx) override;

    virtual boost::optional<Timestamp> getRecoveryTimestamp() const override;

    virtual boost::optional<Timestamp> getLastStableCheckpointTimestamp() const override;

    virtual Timestamp getAllCommittedTimestamp() const override;

    bool supportsReadConcernSnapshot() const final;

    virtual void replicationBatchIsComplete() const override;

    SnapshotManager* getSnapshotManager() const final;

    void setJournalListener(JournalListener* jl) final;

    // ------ kv ------

    KVEngine* getEngine() {
        return _engine.get();
    }
    const KVEngine* getEngine() const {
        return _engine.get();
    }

    KVCatalog* getCatalog() {
        return _catalog.get();
    }
    const KVCatalog* getCatalog() const {
        return _catalog.get();
    }

    StatusWith<std::vector<StorageEngine::CollectionIndexNamePair>> reconcileCatalogAndIdents(
        OperationContext* opCtx) override;

    void loadCatalog(OperationContext* opCtx) final;

    void closeCatalog(OperationContext* opCtx) final;

private:
    using CollIter = std::list<std::string>::iterator;

    Status _dropCollectionsNoTimestamp(OperationContext* opCtx,
                                       KVDatabaseCatalogEntryBase* dbce,
                                       CollIter begin,
                                       CollIter end);

    Status _dropCollectionsWithTimestamp(OperationContext* opCtx,
                                         KVDatabaseCatalogEntryBase* dbce,
                                         std::list<std::string>& toDrop,
                                         CollIter begin,
                                         CollIter end);

    void _dumpCatalog(OperationContext* opCtx);

    class RemoveDBChange;

    stdx::function<KVDatabaseCatalogEntryFactory> _databaseCatalogEntryFactory;

    KVStorageEngineOptions _options;

    // This must be the first member so it is destroyed last.
    std::unique_ptr<KVEngine> _engine;

    const bool _supportsDocLocking;
    const bool _supportsDBLocking;
    const bool _supportsCappedCollections;
    Timestamp _initialDataTimestamp = Timestamp::kAllowUnstableCheckpointsSentinel;

    std::unique_ptr<RecordStore> _catalogRecordStore;
    std::unique_ptr<KVCatalog> _catalog;

    typedef std::map<std::string, KVDatabaseCatalogEntryBase*> DBMap;
    DBMap _dbs;
    mutable stdx::mutex _dbsLock;

    // Flag variable that states if the storage engine is in backup mode.
    bool _inBackupMode = false;
};
}  // namespace mongo